DISTRIBUTED GENERATION
TECHNICAL INTERCONNECTION
REQUIREMENTS INTERCONNECTIONS AT VOLTAGES 50KV AND
BELOW
Proposal for Stakeholder Consultation
© COPYRIGHT 2009 HYDRO ONE NETWORKS LTD. ALL RIGHTS RESERVED
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
LIMITATION OF LIABILITY AND DISCLAIMER Hydro One Networks Inc.’s (“Hydro One”) “Distributed Generation Technical Interconnection Requirements: Interconnections at Voltages 50kV and Below” (the “DG Requirements”) identifies minimum requirements for generation projects connecting to Hydro One’s distribution system. Additional requirements may need to be met by the owner of the generation project to ensure that the final connection design meets all local and national standards and codes and is safe for the application intended. The DG Requirements are based on a number of assumptions, only some of which have been identified. Changing system conditions, standards and equipment may make those assumptions invalid. Use of this document and the information it contains is at the user’s sole risk. Hydro One, nor any person employed on its behalf, makes no warranties or representations of any kind with respect to the DG Requirements, including, without limitation, its quality, accuracy, completeness or fitness for any particular purpose, and Hydro One will not be liable for any loss or damage arising from the use of this document, any conclusions a user derives from the information in this document or any reliance by the user on the information it contains. Hydro One reserves the right to amend any of the requirements at any time. Any person wishing to make a decision based on the content of this document should consult with Hydro One prior to making any such decision. STAKEHOLDER CONSULTATION CONTACT
Please forward questions/comments regarding this Document to the following email address:
EMAIL: [email protected] Hydro One has released this document for public stakeholder consultation. The stakeholder consultation process along with an electronic version of this document is available at www.hydroone.com/DG
REVISION HISTORY
DATE VERSION COMMENTS
February 2009 Proposal – Rev 0 New Report
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
1
TABLE OF CONTENTS
TABLE OF CONTENTS ..................................................................................................................................... 1
LIST OF FIGURES ............................................................................................................................................. 5
LIST OF TABLES ............................................................................................................................................... 6
1 INTRODUCTION .................................................................................................................................. 7
1.1 SCOPE ................................................................................................................................................. 8 1.2 DOCUMENT REPRODUCTION .............................................................................................................. 9 1.3 TERMS AND DEFINITIONS ................................................................................................................. 10
2 HYDRO ONE SYSTEM CHARACTERISTICS ................................................................................. 16
2.1 GENERAL CHARACTERISTICS ........................................................................................................... 16 2.2 SYSTEM FREQUENCY ........................................................................................................................ 16 2.3 VOLTAGE ......................................................................................................................................... 16 2.4 VOLTAGE REGULATION ................................................................................................................... 17 2.5 VOLTAGE AND CURRENT UNBALANCE ............................................................................................. 18 2.6 POWER QUALITY .............................................................................................................................. 18 2.7 FAULT LEVELS ................................................................................................................................. 18 2.8 SYSTEM GROUNDING ........................................................................................................................ 19 2.9 HYDRO ONE NETWORKS INC. DISTRIBUTION SYSTEM FEEDER PROTECTION .................................. 19 2.10 AUTOMATIC RECLOSING (FAULT CLEARING) .................................................................................. 20 2.11 PHASING ........................................................................................................................................... 21 2.12 MULTIPLE SOURCE (NETWORKED) SYSTEM ..................................................................................... 21 2.13 FREQUENCY OF INTERRUPTIONS ...................................................................................................... 21 2.14 ABNORMAL CONDITIONS .................................................................................................................. 22
3 DG TECHNICAL INTERCONNECTION REQUIREMENTS .......................................................... 23
3.1 INTERCONNECTION TECHNICAL REQUIREMENTS............................................................................. 24 3.1.1 Safety ......................................................................................................................................... 24 3.1.2 Adverse Effects to HONI Customers ....................................................................................... 24 3.1.3 Point of Common Coupling ...................................................................................................... 24 3.1.4 Point of Disconnection .............................................................................................................. 26 3.1.5 Voltage ....................................................................................................................................... 27 3.1.6 Voltage and Current Unbalance ............................................................................................... 28 3.1.7 Frequency .................................................................................................................................. 29 3.1.8 Power Factor ............................................................................................................................. 29 3.1.9 Capacity Limitations on Generator Interconnections .............................................................. 30
3.1.9.1 Three Phase Generator Interconnections ........................................................................................... 30 3.1.9.2 Single Phase Generator Interconnections .......................................................................................... 30
3.1.10 Phasing Requirements ............................................................................................................. 31 3.1.11 Interconnection Transformer Configuration............................................................................. 31
3.1.11.1 DG Interconnection to 4-Wire Distribution System ........................................................................... 32 3.1.11.2 DG Interconnection to 3-Wire Distribution System ........................................................................... 41
3.1.12 High Voltage Interrupting Device (HVI) ................................................................................... 44 3.1.12.1 Requirement for Interconnection to 4-Wire Distribution System ...................................................... 45 3.1.12.2 Requirement for Interconnection to 3-Wire Distribution System ...................................................... 45 3.1.12.3 Interrupting Time Requirement .......................................................................................................... 45
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
2
3.1.13 Station Service for Critical Loads ............................................................................................. 45 3.1.14 Grounding .................................................................................................................................. 46 3.1.15 Fault Levels ............................................................................................................................... 48 3.1.16 Resonance Analysis ................................................................................................................. 48 3.1.17 Self-Excitation Analysis ............................................................................................................ 49 3.1.18 Islanding..................................................................................................................................... 49 3.1.19 Synchronization ......................................................................................................................... 49 3.1.20 Insulation Coordination ............................................................................................................. 51 3.1.21 Equipment Rating and Requirements ...................................................................................... 51 3.1.22 Operating Requirements .......................................................................................................... 52 3.1.23 Metering ..................................................................................................................................... 53 3.1.24 DG Facility Acceptance ............................................................................................................ 53
3.2 PROTECTION REQUIREMENTS .......................................................................................................... 54 3.2.1 General Requirements .............................................................................................................. 54 3.2.2 Hydro One Networks Inc. Distribution System Feeder Protection......................................... 55 3.2.3 Sensitivity and Coordination ..................................................................................................... 55 3.2.4 Protection Operating Times ...................................................................................................... 55
3.2.4.1 Interrupting Time for Device Disconnecting Generation ..................................................................... 56 3.2.5 Interrupting Device Rating ........................................................................................................ 56 3.2.6 High Voltage Interrupter (HVI) .................................................................................................. 56 3.2.7 Breaker Fail (BF) ....................................................................................................................... 58
3.2.7.1 BF Protection for HVI ............................................................................................................................ 58 3.2.7.2 BF Protection for LVI ............................................................................................................................ 59
3.2.8 Single Phase Generators ......................................................................................................... 59 3.2.9 Three Phase Generators .......................................................................................................... 61
3.2.9.1 Delta:Wye DGIT Connecting to 3-Wire – Preferred ............................................................................ 63 3.2.9.2 Wye-Gnd:Delta DGIT Connecting to 3-Wire - Alternate ..................................................................... 64 3.2.9.3 Wye-Gnd:Delta:Wye-Gnd Connecting to 3-Wire - Alternate .............................................................. 65 3.2.9.4 Wye-Gnd:Delta DGIT Connecting to 4-Wire - Preferred .................................................................... 66 3.2.9.5 Wye-Gnd:Delta:Wye-Gnd Connecting to 4-Wire - Alternate .............................................................. 67 3.2.9.6 Delta:Wye DGIT Connecting to 4-Wire - Alternate ............................................................................. 68
3.2.10 Phase and Ground Fault Protection Requirement .................................................................. 69 3.2.11 Unbalance Protection................................................................................................................ 70 3.2.12 Feeder Relay Directioning ........................................................................................................ 71 3.2.13 Over Frequency/Under Frequency Protection ........................................................................ 71 3.2.14 Overvoltage/Undervoltage Protection ...................................................................................... 73 3.2.15 Anti-Islanding Protection ........................................................................................................... 74 3.2.16 Requirement for Transfer Trip .................................................................................................. 75
3.2.16.1 Possible Exemption for DGs Smaller than 500kW ........................................................................... 76 3.2.17 DGEO (Distributed Generator End Open) ............................................................................... 76 3.2.18 Unintentional Energization........................................................................................................ 76 3.2.19 Connection to Hydro One Network’s System .......................................................................... 77 3.2.20 Disconnection of DG facilities .................................................................................................. 77
3.2.20.1 Disconnecting DG Generation ........................................................................................................... 78 3.2.20.2 Disconnecting DG HV Ground Sources ............................................................................................ 78
3.2.21 Reconnection of DG Facility ..................................................................................................... 78 3.2.21.1 Reconnection of Hydro One Source (for a transient fault) ............................................................... 78 3.2.21.2 DG Facility Reconnection ................................................................................................................... 79 3.2.21.3 Lock-Out of Hydro One Source (For a Permanent Fault) ................................................................ 81 3.2.21.4 Restoration Following a Sustained Outage or Shutdown ................................................................. 82
3.2.22 LSBS (Low Set Block Signal) ................................................................................................... 82 3.2.23 Auto-Resynchronization/Reconnection ................................................................................... 82 3.2.24 Synchronization Protection ....................................................................................................... 83 3.2.25 Telemetry and Targeting .......................................................................................................... 83
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
3
3.2.26 Transformer Protection ............................................................................................................. 84 3.2.27 Protection from Electromagnetic Interference (EMI) .............................................................. 84 3.2.28 Surge Withstand Performance ................................................................................................. 84 3.2.29 Special Interconnection Protection .......................................................................................... 84 3.2.30 Batteries/DC Supply .................................................................................................................. 85 3.2.31 Protection Scheme Failure ....................................................................................................... 86 3.2.32 Teleprotection Scheme Failure ................................................................................................ 86
3.2.32.1 Transfer Trip Channel Failure ............................................................................................................ 86 3.2.32.2 DGEO Channel Failure ...................................................................................................................... 87
3.2.33 Generators Paralleling for 6 Cycles or Less (Closed Transition Switching) ......................... 87 3.2.34 Instrument Transformers for use in Protection Systems ........................................................ 87 3.2.35 Provision for Future Changes .................................................................................................. 87 3.2.36 Interconnection Protection Acceptance ................................................................................... 88 3.2.37 Protection Summary ................................................................................................................. 89
3.3 CONTROL AND TELECOMMUNICATIONS REQUIREMENTS ................................................................. 90 3.3.1 General ...................................................................................................................................... 90 3.3.2 Control Facilities ........................................................................................................................ 91 3.3.3 Telecommunication Facilities ................................................................................................... 91
3.3.3.1 Reliability Requirements ....................................................................................................................... 92 3.3.4 Operating Data, Telemetry and Monitoring ............................................................................. 93
3.3.4.1 Class 1 Generators ............................................................................................................................... 93 3.3.4.2 Class 2 Generators ............................................................................................................................... 93 3.3.4.3 Class 3 Generators ............................................................................................................................... 94 3.3.4.4 Class 4 Generators ............................................................................................................................... 95 3.3.4.5 Telemetry Reporting Rates .................................................................................................................. 95
3.3.5 Monitoring Reporting................................................................................................................. 96 3.4 PERFORMANCE REQUIREMENTS ....................................................................................................... 96
3.4.1 Power Quality ............................................................................................................................ 96 3.4.1.1 Voltage Fluctuations (Flicker) .............................................................................................................. 97 3.4.1.2 Voltage and Current Harmonics........................................................................................................... 97 3.4.1.3 Voltage and Current Unbalance........................................................................................................... 98 3.4.1.4 Limitation of DC Injection ..................................................................................................................... 98
3.4.2 Disturbances .............................................................................................................................. 99 3.4.3 Generator ................................................................................................................................... 99
3.4.3.1 Reactive Power Requirements ............................................................................................................ 99 3.4.3.2 Speed Governors ................................................................................................................................ 100 3.4.3.3 Excitation Equipment .......................................................................................................................... 101
4 METERING REQUIREMENTS ........................................................................................................103
5 CONNECTION PROCESS REQUIREMENTS .................................................................................103
5.1 IMPLEMENTATION ...........................................................................................................................103 5.2 CONNECTION AGREEMENT ..............................................................................................................104
6 COMMISSIONING AND VERIFICATION REQUIREMENTS ......................................................105
6.1 HYDRO ONE NETWORKS INC. COVER PROCESS ...........................................................................105 6.2 HYDRO ONE REQUIREMENTS FOR COMMISSIONING AND VERIFICATION ........................................105
7 MAINTENANCE REQUIREMENTS ................................................................................................107
7.1 PROTECTION AND CONTROL SYSTEMS EQUIPMENTS ......................................................................107
8 REPORTING REQUIREMENTS FOR DGS .....................................................................................108
9 REFERENCES ....................................................................................................................................110
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
4
A APPENDIX A - DEVICE NUMBER DESCRIPTION .......................................................................113
B APPENDIX B – NEUTRAL REACTOR AND GROUNDING TRANSFORMER IMPEDANCE
CALCULATIONS FOR INVERTER BASED DG FACILITIES ......................................................114
C APPENDIX C – TIMING DIAGRAMS ..............................................................................................115
D APPENDIX D – ANTI-ISLANDING PROTECTION ........................................................................119
E APPENDIX E – DGEO & LSBS DESIGN CONSIDERATIONS ......................................................134
F APPENDIX F – EXAMPLE OF A SEQUENCE OF EVENTS DURING FAULT CONDITIONS...135
G APPENDIX G – CONFIRMATION OF VERIFICATION EVIDENCE REPORT ..........................137
H APPENDIX H – DISTRIBUTION POLICY – METERING FOR DG - NOP 041 ...........................145
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
5
List of Figures
FIGURE 1: SIMPLIFIED SLD – SHOWS CLEARLY IDENTIFIED PCC .......................................................................... 25
FIGURE 2: PREFERRED DGIT CONFIGURATION FOR 4-WIRE DISTRIBUTION SYSTEMS ............................................. 34
FIGURE 3: ALTERNATE DGIT CONFIGURATION FOR 4-WIRE DISTRIBUTION SYSTEMS ............................................ 36
FIGURE 4: ALTERNATE #2 DGIT CONFIGURATION................................................................................................. 39
FIGURE 5: ALTERNATE DGIT CONFIGURATION FOR FACILITIES < 1 MVA .............................................................. 40
FIGURE 6: PREFERRED DGIT CONFIGURATION FOR 3-WIRE DISTRIBUTION SYSTEM ............................................... 42
FIGURE 7: ALTERNATE DGIT CONFIGURATION FOR 3-WIRE DISTRIBUTION SYSTEM .............................................. 43
FIGURE 8: ALTERNATE DGIT CONFIGURATION FOR 3-WIRE DISTRIBUTION SYSTEM .............................................. 44
FIGURE 9: EXAMPLE PROTECTION FOR A SINGLE PHASE GENERATOR ................................................................... 60
FIGURE 10: PREFERRED CONNECTION FOR 3-WIRE DISTRIBUTION SYSTEM ............................................................ 63
FIGURE 11: ALTERNATE CONNECTION FOR 3-WIRE DISTRIBUTION SYSTEM ........................................................... 64
FIGURE 12: ALTERNATE CONNECTION FOR 3-WIRE DISTRIBUTION SYSTEM ........................................................... 65
FIGURE 13: PREFERRED CONNECTION FOR 4-WIRE DISTRIBUTION SYSTEM ............................................................ 66
FIGURE 14: ALTERNATE CONNECTION FOR 4-WIRE DISTRIBUTION SYSTEM ........................................................... 67
FIGURE 15: ALTERNATE CONNECTION FOR 4-WIRE DISTRIBUTION SYSTEM ........................................................... 68
FIGURE 16: NPCC DIRECTORY D2 REQUIREMENT ............................................................................................... 72
FIGURE 17: NO TRANSFER TRIP WITH 500MS RECLOSURE UPSTREAM ..................................................................115
FIGURE 18: NO TRANSFER TRIP WITH 1S RECLOSURE UPSTREAM ........................................................................116
FIGURE 19: TRANSFER TRIP WITH 500MS RECLOSURE UPSTREAM ........................................................................117
FIGURE 20: TRANSFER TRIP WITH 1S RECLOSURE UPSTREAM ..............................................................................118
FIGURE 21: TYPICAL DISTRIBUTION SYSTEM WITH DG INTERCONNECTIONS .........................................................129
FIGURE 22: DGEO & LSBS DESIGN CONSIDERATION .........................................................................................134
FIGURE 23: SEQUENCE AND TIMING DIAGRAM FOR TRANSIENT FAULTS ..............................................................135
FIGURE 24: SEQUENCE AND TIMING DIAGRAM FOR PERMANENT FAULT ...............................................................136
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
6
List of Tables
TABLE 1: VOLTAGE LIMITS 0 TO 50,000V ON DISTRIBUTION SYSTEM ................................................................... 17
TABLE 2: OPERATING FREQUENCY RANGE ........................................................................................................... 29
TABLE 3: RESYNCHRONIZATION REQUIREMENTS .................................................................................................. 50
TABLE 4: ARRESTER RATINGS .............................................................................................................................. 51
TABLE 5: TYPICAL PROTECTIONS REQUIRED FOR SINGLE PHASE DG FACILITIES ................................................... 60
TABLE 6: TYPICAL PROTECTIONS FOR THREE PHASE DGS ..................................................................................... 62
TABLE 7: OVER/UNDER FREQUENCY PROTECTION SET POINTS AND CLEARING TIMES ........................................... 72
TABLE 8: OVER/UNDER VOLTAGE PROTECTION SETTING AND CLEARING TIME ..................................................... 73
TABLE 9: DG CLASSIFICATION ............................................................................................................................. 90
TABLE 10: UNPLANNED TELECOMMUNICATION FAILURE RATES AND REPAIR TIMES.............................................. 92
TABLE 11: TELEMETRY REPORTING RATES........................................................................................................... 95
TABLE 12: PST AND PLT FLICKER LIMITS ............................................................................................................. 97
TABLE 13: CURRENT HARMONIC LIMITS .............................................................................................................. 98
TABLE 14: INCIDENT LOGGING ...........................................................................................................................109
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
7
1 Introduction
This ―Distributed Generation Technical Interconnection Requirements – Interconnections at
Voltages 50kV and Below‖ outlines the technical requirements to install or modify
Distributed Generation (DG) projects connected to HONI‘s sub-transmission and
distribution (systems at ≤ 50kV) feeders. Technical requirements are defined accordingly to
the size and type of generation. This document is designed to provide an expeditious
interconnection to Hydro One Networks Inc. sub-transmission and distribution system that
is both safe and reliable.
This document, ―Hydro One Networks Inc. Distributed Generation Technical Interconnection
Requirements – Interconnections at Voltages 50kV and Below‖ was prepared by Hydro One
Networks Inc. (henceforth referred to as HONI) to guide generator owners and proponents
in connecting distributed generators (DGs) to HONI‘s distribution and sub-transmission
system. It applies to all interconnecting generators.
The additions of DGs to HONI‘s system introduces changes to the sub-transmission and
distribution system and its response. It is imperative that a technically sound, reliable and
safe interconnection between the DGs and HONI is achieved and this requires diligence
from all parties involved. The requirements in this guideline need to be understood by
designers, consultants, equipment vendors, manufacturers, DG owners, and operators of
the DG‘s and HONI‘s system. These requirements will ensure that the interconnection of
the DG to HONI‘s system will:
protect the integrity of HONI system and guarantee reliable and quality service to
HONI‘s customers,
ensure that the interconnection is safe at all times for HONI‘s employees, HONI‘s
customers, DG owners and operators, and for the general public.
be consistent with the requirements of the OEB and all applicable standards
meet all of HONI‘s protection, operating and metering requirements.
This interconnection standard has been developed with reference to the Canadian
Standards Association such as C22.3 No. 9-08 – Interconnection of Distributed Resources
and Electricity Supply Systems and international standards such as the Institute of
Electrical and Electronics Engineers (IEEE) Standard 1547 – Draft Application Guide for
IEEE Standard 1547, Interconnecting Distributed Resources with Electric Power Systems.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
8
This document does not constitute a design handbook. DG owners who are considering
the development of a generation facility intended for connection to HONI‘s system1 should
engage the services of a professional engineer and/or a registered consulting firm qualified
to provide design and consulting services for electrical interconnection facilities in the
Province of Ontario.
1.1 Scope
This document establishes criteria and requirements for the interconnection of DGs to
the distribution and sub-transmission system. It has been tailored specifically to define
the requirements for connecting DGs to HONI‘s distribution and sub-transmission
system with an operating voltage of 50,000 volts (50kV) or lower. It applies to all
induction generators, synchronous generators and inverter-based generators (solar
photovoltaic, fuel cell, induction generator with a static power converter or permanent
magnet generator with a static power converter). This document contains information
pertaining to HONI‘s system and identifies potential issues, such as protection, safety,
coordination, reliability and operation which shall be considered at different stages of the
project.
Chapter 2, ―Hydro One System Characteristics‖ provides operating characteristics of
HONI‘s sub-transmission and distribution system. It has been included in this document
to ensure that DG owner is aware of HONI‘s sub-transmission and distribution system
behaviour. Chapter 2 contains no requirements for the interconnection of DGs and has
been provided for informational purposes only.
The following sections of this document constitute the requirements that the DG owner
must comply with in order to connect to HONI‘s systems:
Chapter 3 - DG Technical Interconnection Requirements
Chapter 4 - Metering Requirements
Chapter 5 - Connection Process Requirements
Chapter 6 - Commissioning and Verification Requirements
Chapter 7 - Maintenance Requirements
Chapter 8 - Reporting Requirements for DGs
1 This document also applies to DGs connecting to Hybrid Feeders (feeders owned partially by HONI)
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
9
Certain requirements have a separate ―Design Considerations‖ heading which is clearly
defined. This information has been provided for informational purposes to aid in the
design of the DG facility in certain cases and does not represent a requirement. HONI
does not take any responsibility for this information and the engineering consultant
designing the DG facility can decide whether to take the information into consideration
when designing the project.
It is the DG owner‘s responsibility to ensure that all requirements are met. These
requirements have been developed to ensure that HONI‘s sub-transmission and
distribution system is protected from the DG facility. Additional requirements may be
necessary to address unique situations and the DG owner shall be advised of any such
requirements at the appropriate stage.
Certain requirements of this document state that a deviation from the preferred option
(alternative) is available or that certain requirements may be not apply for certain
installations. Any exemptions require written approval from HONI.
This document does not identify any generator protections and the DG Owner shall
ensure that adequate generator protections are installed that will protect the generator
from any situation, including problems originating from HONI‘s sub-transmission and
distribution system.
1.2 Document Reproduction
This document may be reproduced or copied in whole or in part provided that credit is
given to Hydro One Networks Inc. and is not sold for profit.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
10
1.3 Terms and Definitions
The Term Is defined as…
ANSI American National Standards Institute
Anti-Islanding Protection system aimed at detecting islanded conditions (see island) and tripping the DG facility from the distribution system if an island forms
AVR Automatic Voltage Regulator
BF Breaker Fail
Breaker Fault Interrupting Device – may be a breaker, circuit switcher, HVI, LVI
CCRA Connection Cost Recovery Agreement
CEA The Canadian Electricity Association
CIA Connection Impact Assessment
Class 1 DG DG aggregate capacity at PCC < 250kW
Class 2 DG 250kW ≤ DG aggregate capacity at PCC < 1500kW
Class 3 DG 1.5MW ≤ DG aggregate capacity at PCC < 10MW
Class 4 DG DG aggregate capacity at PCC > 10MW
Clearing Time See Trip Time
CO
Central Office – A local telephone company office that provides a central point for the termination of telecommunication lines and trunks. And where they can be interconnected.
CSA The Canadian Standards Association
DESN Dual Element Spot Network – Type of TS
Distributed Generation (DG)
Unregulated power generators connected to a distribution system through a Point of Common Coupling
Distributed Generator (DG)
See Distributed Generation
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
11
Distributor The electric utility owning or operating the distribution lines
Distribution System
Any power line facilities under the operating authority of the Wires owner (HONI or LDC). Distribution power line facilities usually operate below voltages of 27.6kV nominal, line to line
DG See Distributed Generation *Formerly referred to as EG – Embedded Generator
DGEO
Distributed Generator End Open – A Signal used to confirm the status of the generator breaker – used to prevent out-of-phase reclosing onto the generator *Formerly referred to as EGEO – Embedded Generator End Open
DGIT See DG Interconnection Transformer
DG Facility All equipment including generators, interface transformer, protections, and line on DG side of the PCC
DG Interconnection Transformer
The transformer used to step up the voltage from the DG to distribution levels
DG Owner The entity which owns or leases the DG facility
DS Electrical station that is used to step down a sub-transmission voltage to a distribution voltage for distribution to the end use customer
DSC Distribution System Code
EMI Electromagnetic Interference
ESA Electrical Safety Authority
F Class Feeder Distribution feeder emanating from a HONI DS or HVDS
Feeder a single 1 phase or 3 phase line emanating from a substation to supply load
Ferroresonance
Phenomenon caused by the interaction of system capacitance and nonlinear inductance of a transformer, usually resulting in very high transient or sustained overvoltage
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
12
GPR
Ground Potential Rise – IEEE defines this as the voltage that a station grounding grid may attain relative to a distant grounding point assumed to be at the potential of remote earth
Harmonics Sinusoidal voltages and currents at frequencies that are integral multiples of the fundamental power frequency
High Voltage In this document, high voltage refers to HONI system voltage – can be referred to as medium voltage
HONI Hydro One Networks Inc.
HVDS
High Voltage Distribution Station – Distribution station connected directly to HONI transmission system (115kV system). Stepping down transmission voltage to distribution voltage for distribution to the end use customer
HVI High Voltage Interrupter – any breaker/fault clearing device that is on the HONI side of the DGIT – voltage rating is usually at medium voltage distribution level
Hybrid Feeders Feeders owned partly by HONI and partly by other entities (e.g. HONI owns the first 50% of the feeder, and an LDC own the rest of the feeder).
IEEE The Institute of Electrical and Electronics Engineers
IED Intelligent Electronic Device
IESO Independent Electricity System Operator
Interconnection facility
Physical connection of DG to HONI's distribution system which allows parallel operation to occur
Interconnection Point
See PCC
Island An operating condition where a DG(s) is (are) supplying load(s) that are not paralleled and synchronized with the main electric utility (electrically separated)
LDC Local Distribution Company. An entity that owns a distribution system for the delivery of energy to consumers from the IESO-controlled grid
Load The amount of power supplied or required at a specific location
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
13
Load Factor Ratio of average load during a designated period to the peak (maximum) load in the same period
Load Flow Study Steady state computer simulation study of voltages and currents in the distribution system
LSBS
Low Set Block Signal – signal sent over same channel as DGEO which blocks the Low Set Instantaneous Protections at HONI‘s stations to prevent inadvertent trips due to transformer inrush during energization.
LVI Low Voltage Interrupter
Medium Voltage See High Voltage
M Class Feeder Distribution feeder emanating from a HONI TS – usually ≥ 24.9kV
NDZ Non Detection Zone – range where passive anti-islanding protection may not operate within required time due to the small mismatch between generation and load
NPCC NorthEast Power Coordinating Council
OEB Ontario Energy Board
OESC Ontario Electrical Safety Code
OGCC Ontario Grid Control Centre
Parallel Operation The state and operation where the DG Facility is connected to the Sub-transmission or Distribution System and supplying loads along with the electric grid.
PCC Point of Common Coupling
Point of Connection The point where an interconnection system is electrically connected to the DG facility. Can be the same as PCC. Refer to Figure 1 for details.
Pst A measure of short-term perception of flicker obtained for a ten minute interval
PSS Power System Stabilizer
Plt A measure of long-term perception of flicker obtained for a two-hour period
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
14
Protection Scheme Protection functions, including associated sensors, relays, CTs, PTs, power supplies, intended to protect a distribution system or interconnected facility
SLD Single Line Diagram
Resonance A tendency of a system to oscillate at maximum amplitude at certain frequencies, usually resulting in very high voltages and currents
RLSS Rotational Load Shedding Schedules
Stabilized Distribution System returning to normal (frequency and voltage) after a disturbance for a period of 5 minutes or as determined by the Wires Owner
Sub-transmission 27.6kV or 44kV HONI distribution lines
Synchronized See Parallel Operation
Telemeter Transfer of metering data using communication systems
THD
Total Harmonic Distortion – a measurement of the harmonic distortion present. It is defined as a ratio of the sum of the powers of all harmonic components to the power of the fundamental frequency
TOV Temporary Overvoltage – oscillatory power frequency overvoltages of relatively long duration – from a few cycles to hours.
Transmission System
Any power line facilities under the operating authority of the Wires Owner usually operating at higher then 50kV voltages, line to line
Transfer Trip A signal sent over communication channels from upstream devices commanding the DG to disconnect from HONI's distribution system
Trip Time The time between the start of the abnormal condition to the time where the system disconnects and ceases to energize the distribution system
TS Electrical station that is used to step down transmission voltage to a sub-transmission voltage for distribution to the end use customer and DS stations
TT See Transfer Trip
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
15
Type Test Test performed on a sample of a particular model/device to verify its operation and design
Wires Owner Utility which owns and/or operates the distribution system
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
16
2 Hydro One System Characteristics
This section describes the characteristics of Hydro One Networks Inc. Distribution System
and identifies aspects that must be taken into consideration when designing a generation
facility that will be interconnected with HONI‘s distribution system. The DG owner must be
able to operate within the ranges specified in this section. In this document, HONI‘s
distribution system may refer to either three phase systems or single phase systems
operating at voltages of 50kV and below – includes systems falling under the definition of
distribution and sub-transmission system. This section contains no requirements for the
interconnection of DGs and has been provided for informational purposes only.
2.1 General Characteristics Most distribution circuits (feeders) in HONI‘s distribution system are supplied radially
from a single substation (point of supply). In some areas, some feeders may have
alternate points of supply, but will be operated with more than one source of supply only
momentarily during switching operations. HONI‘s distribution feeders operate at the
following voltages (phase-phase/phase-neutral): 44kV (3-Wire), 27.6/16kV, 25/14,4kV,
13.8/8kV, 12.48/7.2kV, 8.32/4.8kV, 4.16/2.4kV.
2.2 System Frequency The nominal frequency of HONI‘s system is 60Hz. During normal operation (steady
state), the frequency may deviate from 59.3Hz to 60.5Hz, or as supplied by the
transmission system. Under contingencies the frequency deviations may be larger.
2.3 Voltage The CSA Standard CAN3-C235-83 ―Preferred Voltage Levels for AC Systems, 0 to
50,000V Electric Power Transmission and Distribution‖ provides general guidance for
the steady state service voltage levels on the distribution system. Customers supplied
by the distribution feeder must have adequate voltage levels as per this standard, with
and without distributed generation supplying power for minimum and maximum loading
conditions. The operating voltages found on the distribution feeder vary depending on
load variation, generation variation and contingency situations. Hydro One Networks
standard for voltages on HONI‘s distribution system at the point of delivery during
normal operation is typically in the range of +/- 6% of nominal voltage. The CSA voltage
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
17
standard (summarized below in Table 1) and the voltage levels at the PCC specified in
the CIA report to the DG Owner should be followed by the DG owner.
These values may be exceeded under abnormal conditions. Voltage transients and
swells can occur on the distribution system at any time due to lightning strikes, single
phase to ground faults, and switching, among others. The interconnected DG must be
able to operate within the extreme voltage level variations shown in this document and
must ensure that the insulation levels and protective equipment in their facility can
withstand abnormal voltages on the distribution system.
Table 1: Voltage Limits 0 to 50,000V on Distribution System
Low Limit (% of nominal) Nominal Voltage (%) High Limit (% of nominal)
94 100 106
2.4 Voltage Regulation HONI utilizes voltage regulating devices throughout the distribution system to maintain
an adequate voltage profile along the feeders and ensure that customers receive
voltages in the range specified in CSA CAN3-235-83. These regulating devices include
line voltage regulators, regulating stations and transformer under-load tap changers at
the Transformer Station (TS) or Distribution Station (DS). HONI operates all voltage
regulating devices on its distribution system to 125V ±1.5V on a 120V base.
The distribution system was designed to correctly operate for unidirectional power flow
(from the substation to the customer). Voltage regulating devices were designed to
correctly operate under these conditions, however, with the addition of DGs into the
system, the power flow can be reversed when the DG is supplying power which may
inhibit the voltage regulators to properly regulate the voltage on the feeder. Due to this,
wherever there is a possibility of reverse power flow, regulating devices (line voltage
regulators, regulating stations and transformer under-load tap changers at the
Transformer Station (TS) or Distribution Station (DS)) on HONI‘s distribution system
shall be changed to suitable devices that allow bi-directional flow.
Steady-state voltage variations at the point of common coupling (PCC) and throughout
the distribution system are limited to +/- 6% of the nominal voltage.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
18
2.5 Voltage and Current Unbalance Voltage unbalance due to unbalanced loading and single phase voltage regulation is
typical and inevitable and may reach 2% voltage and 10-20% of total feeder load current
unbalance along certain sections of the feeder, including at the PCC. The DG facility
must not further deteriorate existing unbalanced conditions. In some areas of HONI‘s
distribution system these unbalances may be higher and the DG owner shall contact
HONI to obtain site-specific data. During abnormal conditions such as faults and single
pole reclosing, the unbalance may be very high (current unbalance may be significantly
higher than 20%).
As per NEMA MG 1-1998, the formula for voltage unbalance is:
𝑉𝑜𝑙𝑡𝑎𝑔𝑒 𝑈𝑛𝑏𝑎𝑙𝑎𝑛𝑐𝑒 % =100 ×(𝑚𝑎𝑥𝑖𝑚𝑢𝑚 𝑣𝑜𝑙𝑡𝑎𝑔𝑒 𝑑𝑒𝑣𝑖𝑎𝑡𝑖𝑜𝑛 𝑓𝑟𝑜𝑚 𝑎𝑣𝑒𝑟𝑎𝑔𝑒 𝑣𝑜𝑙𝑡𝑎𝑔𝑒 )
(𝑎𝑣𝑒𝑟𝑎𝑔𝑒 𝑣𝑜𝑙𝑡𝑎𝑔𝑒 )
2.6 Power Quality In HONI‘s distribution system, all interconnected equipment must comply with HONI‘s
standards for power quality. IEEE Std. 519, IEEE Recommended Practices and
Requirements for Harmonic Control in Electric Power Systems, has been accepted by
industry to provide guidance for appropriate performance and power quality limits such
as voltage flicker and harmonic contribution limits. This standard states that the
recommended practice for utilities is to limit individual frequency voltage harmonics to
3% of the fundamental frequency and the total voltage harmonic distortion (THD) to 5%
on the utility side of the PCC. These limits presented in this standard should be used as
a design criterion when designing the DG facilities as worst case scenario under normal
operation conditions.
2.7 Fault Levels Fault levels on HONI‘s distribution system vary greatly throughout the system. Factors,
such as location, generation pattern, and contingencies all contribute to varying fault
levels. These fault levels may also change with time as the system expands and new
generation comes online. The DG proponents will receive fault levels for the
distributions system as well as system impedances for a site that is considered from
Hydro One Networks. Maximum allowable fault levels will be provided as well.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
19
The DG interconnection facilities shall be designed with the fault levels, and maximum
allowable fault levels considered. The X/R ratios must be evaluated for the equipment
selected and the DG facilities shall not increase the fault levels beyond the distribution
system design levels for maximum faults. If the levels increase beyond the existing
design limits, changes to the distribution system equipment will be required.
2.8 System Grounding HONI‘s distribution facilities are typically operated as uni-grounded (for 3 phase – 3 wire
systems) or multi-grounded (for 3 phase – 4 wire systems). The transformer neutral at
the substation is either solidly grounded (without any impedance) or effectively grounded
through a low impedance at the station (through a neutral reactor, resistor or grounding
transformers) to limit the fault levels on ground faults.
Distribution facility and DG facility grounding shall conform to the Ontario Electric Safety
Code (OESC) and Section 10 of the Canadian Electrical Code.
2.9 Hydro One Networks Inc. Distribution System Feeder Protection
HONI will provide to the DG Owner, upon request, all applicable information about
HONI‘s distribution system protection scheme on the feeder interconnecting with the DG
facility. The general feeder protection scheme utilized on HONI‘s distribution system
where DGs are interconnecting is described below for M Class feeders emanating from
TSs. The feeder protections can be divided into three states:
High Set Instantaneous – Instantaneous protection for close-in feeder faults.
Usually set to the first tap on the feeder. Traditionally employed High Set 50A/50NA
elements. Current HONI standard for feeders with DGs interconnected is to use the
Zone 1 distance (21 – Phase & Ground) element to set the High Set Instantaneous
protection.
Low Set Instantaneous – Instantaneous protection for faults on the entire length of
the feeder. Used primarily as a fuse saving scheme to clear transient faults before
fuse elements start melting. Traditionally utilized using Low Set 50B/50NB
elements. Current HONI standard for feeders with DGs interconnected is to use the
Zone 2 distance (21 – Phase & Ground) element to set the Low Set Instantaneous
protection.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
20
Timed – Directionally supervised 51/51N overcurrent elements load/fault
discrimination are used for timed protection of HONI‘s distribution feeders. They are
set to detect and clear faults in their required zone. All timed overcurrent elements
on the distribution system are coordinated with each other to ensure that a minimum
number of customers are affected in the case of permanent faults. For the timed
overcurrent elements to function properly, all DG sources (both positive sequence
and zero sequence sources) need to be removed from the distribution system –
refer to the requirements in Section 3.1.12 – High Voltage Interrupting Device.
F Class feeders, radiating from DSs, have varying levels of sophistication in their
protection schemes. The protections scheme on F Class feeders may need to be
upgraded to accommodate DGs.
2.10 Automatic Reclosing (Fault Clearing) HONI‘s sub-transmission and distribution system, utilizes automatic reclosing to quickly
clear non permanent faults on the sub-transmission and distribution system, thus,
quickly restoring supply. Generally feeder circuit breakers at Transmission Stations use
single-shot reclosing and reclosers at Distribution Stations and other locations along the
distribution feeder may use single-shot or multi-shot automatic reclosing. Reclosers
may trip a single phase, when single phase loads are connected to the feeder, or all
three phases. If, after the preset number of reclose attempts, the fault persists, the
recloser will lockout and stay open (single phase or three phases will be tripped). The
reclose ―dead time‖ (time that the distribution line is de-energized between reclose
attempts) varies depending on location and type of recloser and can be obtained from
HONI along with all other relevant protection data.
The DG facilities shall be designed with auto-reclosing considered. The generator
protections need to coordinate with the reclosing times of HONI‘s interrupting devices to
ensure that HONI‘s distribution system will not attempt to reclose when the DG is still
connected, risking an out-of-phase reclosing (refer to Section 3 for requirements). If
single phase tripping is employed on HONI‘s distribution system, the DG shall be
designed to protect itself from the unbalance that results. The DG may reconnect to the
system after HONI‘s system voltage and frequency return to nominal and after the
requirements of Section 3.2.19 and Section 3.2.21 of this document are met.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
21
2.11 Phasing Conductor phasing may not be standardized and as such, the phase sequence and the
direction of rotation shall be coordinated between the DG proponent and HONI.
2.12 Multiple Source (Networked) System In some areas of HONI‘s distribution, there may be instances where portions of a
distribution feeder are supplied from two different sources (such as during switching
events). The added complexity in these instances shall be considered when designing
the DG facilities and every precaution shall be taken to ensure that out-of-phase
reclosing does not occur whenever interconnecting to a networked system or a system
capable of source transferring.
The DG facility is required to be removed from service if the source (normal feed) has
changed from the one studied in the CIA and remain disconnected until normal supply
has been restored.
If this requirement changes and multiple sources (alternate feeder) configurations
become available for DGs, this document will be updated to reflect any policy changes.
The DG Owner will be required to have additional protections to alternative feeder
supplies at that time if they wish to have the capability of connecting to alternate
sources.
2.13 Frequency of Interruptions HONI‘s distribution feeders are mainly unshielded overhead lines spanning vast
distances. They are equipped with insulation levels adequate to withstand expected
voltages. Lighting strikes directly to HONI‘s distribution line result in flashovers of the
insulators on the feeder and result in protection systems tripping the distribution line.
The faults may be temporary in which case a successful reclose will occur (most faults
on overhead distribution lines are temporary in nature), or they may be permanent and
trip the line until repair crews are dispatched and repair the feeder.
Due to the vast distances of the lines and the possibility of frequent momentary trips, the
DG proponent should consider a design that will be suitable for these conditions (such
as auto-restart).
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
22
2.14 Abnormal Conditions The DG Owner shall consider all possible disturbances which occur on HONI‘s
distribution system while designing their protection system to ensure that HONI‘s
customers and the DG facility are protected. These disturbances can include, but are
not limited to the following:
Faults on the system
Frequency excursions
Partial or complete loss of load
Transient overvoltages – caused by lightning strikes or switching operations
Temporary overvoltages
Single phasing of the three phase system – caused by HONI‘s protection
equipment, switching or broken conductors
Ferroresonance, overvoltages due to resonance conditions
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
23
3 DG Technical Interconnection Requirements
This ―DG Technical Interconnection Requirements‖ section defines and describes the
technical requirements for the distribution system, and the generation facility (generators
and interconnection equipment as described in the Distribution System Code) for DG
interconnection. The first part, Section 3.1, defines the interconnection technical
requirements, the second part, Section 3.2, defines the protection requirements, the third
part, Section 3.3, defines the control, telecommunications, and monitoring requirements for
interconnected DGs and the fourth part, Section 3.4 defines the performance requirements
such as power quality and reactive power requirements. These requirements need to be
followed in order to connect to HONI‘s sub-transmission, distribution system and hybrid
feeders. In this document, HONI‘s distribution system may refer to either three phase
systems or single phase systems operating at voltages of 50kV and below – includes
systems falling under the definition of distribution and sub-transmission system. They
encourage safe operation and minimize the impact that the DG facility has on HONI‘s
distribution system and in turn to HONI‘s customers. Certain requirements in Section 3 of
this document state that a deviation from the preferred option (alternative) is available or
that certain requirements may be not apply for certain installations. Any exemptions require
written approval from HONI.
Certain requirements have a separate ―Design Considerations‖ heading which is clearly
defined. This information has been provided for informational purposes to aid in the design
of the DG facility in certain cases and does not represent a requirement. HONI does not
take any responsibility for this information and the engineering consultant designing the DG
facility can decide whether to take the information into consideration when designing the
project.
Beyond the requirements presented here in this document, the DG facility must meet all
applicable national, provincial, local and other HONI safety and construction codes. This
guide is intended to provide protection to HONI‘s distribution system and does not cover
protection of the DG facilities. It is the responsibility of the DG Owner to protect its facilities
in a manner that will ensure that events such as outages, short circuits, unbalances,
excessive zero sequence currents and negative sequence voltage, and other disturbances
do not cause damage to the DG facility.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
24
3.1 Interconnection Technical Requirements
3.1.1 Safety
The DG interconnection shall not create a safety hazard to HONI‘s personnel,
customers, general public and personnel working in the DG facility. Safety is of
primary concern and should be the main consideration when designing the facility.
The primary concern of this document is to provide interconnection specifications
to ensure that safety will be maintained. All equipment shall be approved by the
appropriate authorities (e.g. CSA). The DG facility must have ESA approval prior
to a Distribution Connection Agreement with HONI. The DG facilities must be
maintained throughout the life of the assets to ensure that the DG facility is
operating as designed.
3.1.2 Adverse Effects to HONI Customers
The interconnection of the DG facilities must not materially compromise the
reliability or restrict the operation of HONI‘s distribution system.
The interconnection must not degrade power quality below acceptable levels and if
it is found that it significantly deteriorates the performance of the distribution
system, it shall be disconnected from the distribution system until appropriate
measures are taken to mitigate these negative impacts.
3.1.3 Point of Common Coupling
The Point of Common Coupling (PCC) is the location where Hydro One Networks
distribution facilities (wires) are connected to the DG Facilities or DG proponent‘s
wires and where the transfer of electric power between the DG and HONI takes
place. The PCC must be identified on the single line diagram (SLD), as shown
below in Figure 1.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
25
Figure 1: Simplified SLD – Shows Clearly Identified PCC
The DG owner is responsible for the design, construction, maintenance and
operation of the facilities and equipment on the DG side of the PCC (all equipment
on the DG side of the PCC shall be approved in accordance with Section 2-004 of
the Ontario Electrical Safety Code) while HONI will coordinate the design,
construction, maintenance and operation of the facilities on HONI‘s side of the
PCC. HONI will carry out the engineering, design and construction required for
additional changes to HONI‘s system in order to facilitate the DG interconnection.
The DG owner may be responsible for the cost of such changes.
In certain instances, either HONI or the DG owner may require that their
equipment be located on the other side of the PCC. If this is the case, the DG
owner must provide the necessary space for HONI to install such equipment and
HONI is to approve this site. A 120V AC power service is to be available.
When specifications and parameters (such as voltage, frequency, and power
quality) are mentioned throughout this document, they must be met at the PCC
unless otherwise stated throughout the document.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
26
3.1.4 Point of Disconnection
To ensure a means of electrically isolating the DG facility from HONI‘s distribution
system, a means of isolation must be provided (Load Break Switch) and must be in
compliance with the OESC. To conform with recognized standards (this complies
with OESC Rule 84-026, IEEE Standard 1547 Clause 4.1.7 and the Distribution
System Code (DSC) Appendix F.2 Section 1), the disconnect or isolation device
must:
be a Load Break Switch (capable of interrupting maximum rated load)
be readily accessible by Hydro One
be lockable
have no keyed interlocks
be Gang Operated (for three phase installations)
be a Visible Break type
be of appropriate rating
be located between the Hydro One system and the DG Facility
bear warning to the effect that inside parts can be energized when
disconnecting means is open
be motorized (single phase DG installations exempt)
have a manual override
be required to disconnect the DG facility from HONI‘s distribution system
on a breaker fail condition (protection interface for tripping)
meet all applicable standards and codes (Canadian Electrical Code Part
1 and Part 2)
be capable of being closed onto a fault with complete safety to the
operator – Must not be a source of injury during operation, even when
closed into a faulted system
be capable of being operated without exposing the operator to any live
parts.
This point of disconnection is required for the purpose of work protection of Hydro
One and DG facility personnel. Switching, tagging and lockout procedures shall be
coordinated with HONI. The DG Owner and HONI will mutually agree to the exact
location of the disconnect switch. This switch must not be located in a locked
facility and where DG facilities have H2S or any other hazardous materials present,
it shall be located outside of the hazardous area.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
27
If multiple generators are connected at the DG facility, one disconnect switch must
be capable of isolating all of the generators simultaneously. There may be other
means of meeting this requirement and any proposals must be reviewed by HONI.
3.1.5 Voltage
The DG facility shall ensure that the operation of the DG(s) do(es) not have an
objectionable impact on the voltage at the PCC. The DG owner is responsible for
ensuring that the voltage at the PCC is maintained as per CSA Standard CAN3-
C235-83 ―Preferred Voltage Levels for AC Systems, 0 to 50,000V Electric Power
Transmission and Distribution.‖ Voltage variations at the PCC are limited to +/- 6%
of the nominal voltage under normal operating conditions. Voltages at all load
connections along the feeder must be at least at levels prior to the interconnection
of the DG. HONI will define voltage requirements on a case by case basis in the
CIA. HONI operates all voltage regulating devices on its distribution system to
125V ±1.5V on a 120V base. The introduction of DGs to HONI‘s distribution
system may result in reverse power flow on the feeder. Voltage regulators on
HONI‘s distribution system may require to be upgraded to be capable of handling
reverse flow.
During abnormal conditions, voltage variations may exceed these values. The DG
Facilities must protect themselves from abnormal voltage conditions which the
distribution system is subjected to. These may include voltage transients, sags
and swells caused by lightning, switching, faults, and the loss or switching of
customer loads. Insulation levels and protective equipment must be capable of
withstanding abnormal voltages on HONI‘s distribution system.
The DG should not actively regulate the voltage at the PCC. During normal
operation, the DG must be loaded and unloaded gradually to allow adequate time
for regulating devices on HONI‘s distribution system to respond and avoid
excessive voltage fluctuations.
For DGs connected to HONI‘s 4-wire distribution system, temporary over-voltage
(TOV) that may be caused by the DG facility interconnection should not exceed
125% of nominal system voltage anywhere on the distribution system and under
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
28
no circumstance shall exceed 130%. HONI will advise on action to reduce TOV to
limits.
For power quality parameters such as voltage dip and flicker requirements, see the
Performance Requirements section (Section 3.4).
3.1.6 Voltage and Current Unbalance
Voltage and current unbalance are normal on many distribution feeders as they
supply many single phase loads and thereby all three phases are never equally
loaded. Phase voltage unbalance of 2% and phase current unbalance of 10-20%
of total feeder load is common. Unbalanced loads that result in unbalanced phase
voltages and currents can cause high neutral currents, negative sequence
voltages and currents, zero sequence voltages, thermal overloading of
transformers and 3-phase motors, and can cause protective relaying to mis-
operate.
To protect HONI‘s distribution system and customers, the DG facility must not
further deteriorate existing unbalance conditions at the PCC and the distribution
system. The phase-phase voltage unbalance of three phase DGs must not be
greater than 1% as measured with balanced three phase loading and with no load.
The DG facility should also protect itself from highly unbalanced voltages,
especially when connected to HONI‘s distribution system where single phase
reclosing is used. The DG Interconnection Transformer may supply unbalance
current to support the unbalanced load on the feeder. This unbalance current may
be present even if the generator is out of service. The proportion of unbalance
load current from the DG Interconnection Transformer will vary based on feeder
topology, unbalanced loads, voltage and DG location. During abnormal conditions
such as faults and single pole reclosing, the unbalance may be very high (current
unbalance may be significantly higher than 20%) and it is up to the DG owner to
ensure that the DG facilities are protected from damage due to unbalance.
Single phase DGs connected to a single phase of HONI‘s distribution system are
limited in size (kVA rating) due to the potential impact they may have on
distribution system voltage unbalance (see Section 3.1.9 for size limitations). A
single phase generator must not negatively impact the unbalance of the nearest
three-phase distribution system. Single phase generators shall not cause an
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
29
unbalance of greater than 2% when connected alone. If multiple single phase
generators are installed, they shall be connected so that an equal amount of
generation is applied to each single phase of the distribution line, and this balance
must be maintained if one or more of the generating units go offline.
3.1.7 Frequency
The generators at the DG facility must operate at a nominal frequency of 60Hz.
They must remain synchronously connected for the frequency range presented
below in Table 2. For any frequencies beyond those presented in the table, the
generator is required to trip instantaneously (see Section 3.2.13) and islanding of
DGs connected to HONI‘s distribution system is not allowed at this time.
Table 2: Operating Frequency Range
Generator Size Frequency Range (Hz)
Low Range High Range
≤ 30 kW 59.3 60.5
≥ 30 kW 57.0-59.8 (adjustable set
point) 60.5
* Source: IEEE 1547
3.1.8 Power Factor
The DG facility shall be capable of operating in the preferred power factor range as
specified by HONI, which is typically in the range of 0.9 lag to 0.95 lead. If
warranted by local distribution system conditions (such as disturbing the
distribution system voltage at the PCC), this range could be narrower or wider and
will be specified by HONI. Field settable and fixed dynamic power factor correction
techniques may be required. Induction generators consume reactive power and
the DG Owner may be required to provide reactive power compensation to correct
the power factor at the PCC. Inverters and static power converters must be able to
adjust their power factor in the range of at least ± 0.90 at the PCC.
For DG facilities that are IESO-impactive (Class 4 DGs), the reactive power
compensation at the generator units should be sufficient so as not to cause any
material increase in the reactive power requirements at the transmission system
transformer station due to the operation of the DGs at all load conditions on the
feeder.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
30
3.1.9 Capacity Limitations on Generator Interconnections
Distribution feeders operating at nominal voltage levels of 13 kV or higher are
normally supplied from TS‘s or HVDS‘s. The actual loading for all sections of these
types of feeders shall be based on the thermal loading limits corresponding to the
specific conductor sizes as well as the actual ratings of other series elements (line
switches, regulators, distribution transformers, fuses, etc.) but shall not exceed 400
amps. Distribution feeders operating at nominal voltage levels below 13 kV are
normally supplied from DS‘s. The actual loading for all sections of these types of
feeders shall be based on the thermal loading limits corresponding to the specific
conductor sizes as well as the actual ratings of other series elements (line
switches, regulators, distribution transformers, fuses etc.) but shall not exceed 200
amps.
During emergencies and planned outages, the DG facility is required to be
removed if the source (normal feed) is changed over to an alternate source.
The following is a guide for the acceptable total generation limits for feeders
operating at standard Hydro One nominal voltage levels of ≤ 13kV, 13.8 kV, 25 kV,
27.6 kV and 44 kV. Please note that the actual acceptable generation limits for
feeders are determined from detailed connection impact assessments.
3.1.9.1 Three Phase Generator Interconnections
Three phase DGs connecting to HONI‘s distribution at nominal voltage
levels of 25kV, 27.6kV, and 44kV usually do not exceed 10MW. If the
27.6kV feeder is supplied via a 44kV:27.6kV step-down transformer, the
DG facility will be limited to 5MW per individual connection.
Three phase DGs connecting at lower voltage levels (below 15kV) are
normally supplied by HONI‘s distribution stations. The individual generation
limits of DGs connecting to these feeders shall not exceed 1.0MW.
3.1.9.2 Single Phase Generator Interconnections
Individual single phase generators connecting to feeders operating at
nominal voltage levels of 13.8kV, 25kV, 27.6kV and 44kV are limited to
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
31
150kW output. Single phase generators connecting to feeders operating at
nominal voltage levels less than 13kV are limited to 100kW.
3.1.10 Phasing Requirements
HONI and the DG Owner shall agree upon the phase sequence and direction of
rotation. The DG must connect rotating machines as required to establish correct
rotation.
3.1.11 Interconnection Transformer Configuration
As per the DSC, Appendix F.2 Section 2, the interconnection transformer shall not
cause voltage disturbances or disrupt co-ordination of distribution system ground
fault protection. Annex C of CSA Standard C22.3 No.9-08 discusses different DG
interconnection transformer configurations and presents each ones advantages
and disadvantages.
Since the winding configuration of any three phase transformer(s) between the DG
and HONI will have an impact on the distribution system, both under steady state
and fault conditions, Hydro One Networks has analyzed the different options and
has standardized the DG interconnection transformer configuration. This section
will describe the allowable transformer configurations for the interconnection of
DG‘s to HONI‘s 3-Wire and 4-Wire distribution system. Written approval from
HONI will be required for any alternate configuration. The DG Interconnection
Transformer may supply unbalance current to support the unbalanced load on the
feeder. This unbalance current may be present even if the generator is out of
service. The proportion of unbalance load current from the DG Interconnection
Transformer will vary based on feeder topology, unbalanced loads, voltage and
DG location
This directive applies to all DGs connected directly or indirectly (through a hybrid
feeder) to the HONI distribution system and applies to Class 1, Class 2, Class 3,
and Class 4 generators. Where the DG is connected indirectly to HONI‘s
Transmission or Distribution system through an LDC, HONI will assess the impacts
of the connection to the HONI system.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
32
3.1.11.1 DG Interconnection to 4-Wire Distribution System
Preferred Option HONI‘s preferred transformer interconnection configuration and grounding
for 4-wire distribution systems is shown below in Figure 2, Wye-
Ground:Delta. This configuration will eliminate the damaging TOV
associated with high side delta transformer configurations. A neutral
reactor in the primary winding may be necessary to limit the ground short
circuit current.
Sizing of Neutral Reactor for Conventional (Rotating) Generators
The neutral reactor, Xn shall be sized by the DG Owner and reviewed
during the Connection Impact Assessment based on a Thevenin
Equivalent of the Positive and Zero Sequence Reactance of the DG
facility (example: at the Point of Connection with the Point of
Connection OPEN) that will result in:
1.5 ≤XDG 0
XDG 1≤ 2.5
to achieve an overall Thevenin Equivalent Positive and Zero Sequence
impedance at any point on the feeder with any or all DG sources and
HONI sources In-Service of:
2 <X0
X1 < 3 and
R0X1
< 1
Sizing of Neutral Reactor for DGs with an Inverter Interface
The neutral reactor, Xn shall be sized by the DG Owner and reviewed
during the Connection Impact Assessment based on a Thevenin
Equivalent of the Zero Sequence Reactance of the DG facility
(example: at the Point of Connection with the Point of Connection
OPEN) that will result in:
X0 = 0.6 ± 10% p. u. and X0
R0 ≥ 4
where 1 p.u. is based on the MVA and high side kV rating of the DGIT.
Note: DGIT MVA rating assumed to be approximately equal to the
generation capacity. See Appendix B for calculation examples.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
33
Utilizing this DG interconnection transformer (DGIT) winding configuration
and grounding scheme limits the harmful temporary overvoltages on
HONI‘s distribution system, however, it adds a ground source and can
desensitize HONI‘s protective equipment. Once HONI‘s feeder Low Set
instantaneous protection operates, the DGITs along with the generators
shall be tripped off using a HVI, which is required for all DGs connected via
this transformer configuration (refer to Section 3.1.12 and 3.2.6), as seen in
Figure 2. This disconnects the DG facilities DGITs including any ground
sources, allowing the timed overcurrent protection on HONI‘s distribution
system, such as feeder breaker, inline reclosers, and fuses, to detect all
faults on HONI‘s distribution system and coordinate properly. Please refer
to Section 2.9 for an explanation of HONI‘s distribution system protection
scheme.
This DGIT configuration may require a grounding transformer (zig-zag) to
be connected on the LV side of the DGIT if the DG facility needs to limit the
TOV on the LV side. The ground of the DGIT shall be connected to HONI‘s
neutral conductor and the design of the DG facility shall conform to the
grounding requirements set in Section 3.1.14.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
34
Figure 2: Preferred DGIT Configuration for 4-Wire Distribution Systems
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
35
Alternate Option #1 An alternate DG interconnection transformer configuration for 4-wire
distribution systems is shown in Figure 3. A Wye-ground:Wye-ground
transformer configuration is a viable alternative, however, it is required to
have a delta tertiary winding to limit the harmonic distortion to HONI‘s
distribution system and to limit the TOV‘s on HONI‘s distribution system due
to the introduction of the DG on the feeder if the generator is ungrounded or
high impedance grounded.
Sizing of Neutral Reactor for Conventional (Rotating) Generators
The neutral reactor, Xn shall be sized by the DG Owner and reviewed
during the Connection Impact Assessment based on a Thevenin
Equivalent of the Positive and Zero Sequence Reactance of the DG
facility (example: at the Point of Connection with the Point of
Connection OPEN) that will result in:
1.5 ≤XDG 0
XDG 1≤ 2.5
to achieve an overall Thevenin Equivalent Positive and Zero Sequence
impedance at any point on the feeder with any or all DG sources and
HONI sources In-Service of:
2 <X0
X1 < 3 and
R0X1
< 1
Sizing of Neutral Reactor for DGs with an Inverter Interface
The neutral reactor, Xn shall be sized by the DG Owner and reviewed
during the Connection Impact Assessment based on a Thevenin
Equivalent of the Zero Sequence Reactance of the DG facility
(example: at the Point of Connection with the Point of Connection
OPEN) that will result in:
X0 = 0.6 ± 10% p. u. and X0
R0 ≥ 4
where 1 p.u. is based on the MVA and high side kV rating of the DGIT.
Note: DGIT MVA rating assumed to be approximately equal to the
generation capacity. See Appendix B for calculation examples.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
36
This alternate DGIT configuration will eliminate the need for grounding
transformers on both the HV and LV side of the DGIT. The ground of the
DGIT shall be connected to HONI‘s neutral conductor (as shown in Figure
3) and the design of the DG facility shall conform to the grounding
requirements set in Section 3.1.14. An HVI will be required as per Section
3.1.12.1.
Figure 3: Alternate DGIT Configuration for 4-Wire Distribution Systems
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
37
Alternate Option #2 DG installations which utilize multiple transformers that step up the voltage
directly to the distribution voltage level and connect to HONI distribution
system through a common PCC may be connected as shown in Figure 4.
The transformers at these generators may be connected delta on the high
side depending on the manufacturer, and in order to facilitate
interconnection of these projects, this alternative transformer configuration
can be used.
This alternative may also be used for inverter based DGs whenever it is
more economical to use grounding transformers as opposed to neutral
reactors due to the impedance required (Refer to Section 3.1.14,
Grounding Requirements).
This alternative will require a grounding transformer (zig-zag) to be
connected on the HV side of the DGITs to limit the TOV on HONI‘s
distribution system. This grounding transformer shall be sized by the DG
Owner and reviewed during the Connection Impact Assessment.
Sizing of Grounding Transformer for Conventional (Rotating) DGs
The grounding transformer shall be sized based on a Thevenin
Equivalent of the Positive and Zero Sequence Reactance of the DG
facility (example: at the Point of Connection with the Point of
Connection OPEN) that will result in:
1.5 ≤XDG 0
XDG 1≤ 2.5
to achieve an overall Thevenin Equivalent Positive and Zero Sequence
impedance at any point on the feeder with any or all DG sources and
HONI sources In-Service of:
2 <X0
X1 < 3 and
R0X1
< 1
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
38
Sizing of Grounding Transformer for DGs with an Inverter Interface
The grounding transformer shall be sized by the DG Owner and
reviewed during the Connection Impact Assessment based on a
Thevenin Equivalent of the Zero Sequence Reactance of the DG
facility (example: at the Point of Connection with the Point of
Connection OPEN) that will result in:
X0 = 0.6 ± 10% p. u. and X0
R0 ≥ 4
where 1 p.u. is based on the total MVA rating of the DG Facility (sum of
DGITs MVA ratings) and high side kV rating of the DGIT(s). Note:
DGIT MVA rating assumed to be approximately equal to the generation
capacity. See Appendix B for calculation examples.
The grounding transformer shall be located on the DG side of the HVI –
Refer to Section 3.1.12.1 for HVI requirements. The design should be a
padmount zig-zag transformer installed in accordance to all applicable
codes and standards. It shall be solidly connected (not fused) to ensure
that the transformer is in service at all times. The grounding transformer‘s
ground shall be connected to HONI‘s neutral conductor and the design of
the DG facility shall conform to the grounding requirements set out in
Section 3.1.14.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
39
Figure 4: Alternate #2 DGIT configuration
Alternate Option #3 – Available for Installations < 1 MVA HONI‘s preferred transformer interconnection configuration and grounding
for 4-wire distribution systems has been shown in Figure 2. The following
alternate option shown here in Figure 5 may be allowed in certain cases for
small DGs with an aggregate capacity of less than 1 MVA.
In the presence of single phase reclosing upstream of the DG on HONI‘s
distribution system, consideration should be given to use 3 separate single
phase transformers, as this will eliminate the problems associated with
backfeed onto faulted phases due to a shared magnetic core. Therefore in
the case of a downed conductor, without the presence of a HVI at the DG
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
40
facility to disconnect the transformer, the public would not be put at risk due
to magnetically coupled voltage on the conductor.
This configuration passes harmonics readily and as such, the DG Owner
must ensure that harmonic contributions from the facility are within limits,
otherwise mitigation will be required. A neutral reactor in the primary
winding may be necessary to limit the ground short circuit current and will
be determined in the CIA. The neutral reactor, if needed, shall be sized as
in the preferred option.
Figure 5: Alternate DGIT configuration for facilities < 1 MVA
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
41
3.1.11.2 DG Interconnection to 3-Wire Distribution System
Preferred Option HONI‘s preferred DG interconnection transformer configuration and
grounding for 3-wire distribution systems is shown below in Figure 6, Delta:
Wye-ground. HONI‘s 3-Wire Distribution Systems have been designed to
withstand phase to phase voltages and thus there is no concern of TOV for
these connections. Since TOV is not a problem, HONI prefers this option
as it does not introduce additional ground sources to HONI‘s distribution
system. The requirement for having an HVI installed at the DG facility may
be waived.
If the HVI requirement is waived, the DG Owner shall decide whether or not
to install an HVI. If in the future the requirements change, and the HVI is
required, the DG Owner will be obliged to install one at its own cost. An
LVI (Low Voltage Interrupter on the generator side of the DGIT) will be
required if an HVI is not installed. The design of the DG facility shall take
into consideration the possibility of ferroresonance due to the loss of one or
two phases and shall take steps to ensure that the DG facility is protected
under such an occurrence.
Protection systems shall be designed accordingly to ensure that ground
faults on HONI‘s distribution system are detected.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
42
Figure 6: Preferred DGIT Configuration for 3-Wire Distribution System
Alternate Option #1 A Wye-Ground:Delta DG interconnection transformer on HONI‘s 3-Wire
distribution system as shown in Figure 7 is not a preferred option, however
it may be acceptable if required and will be determined in the CIA. A
neutral reactor in the primary winding may be necessary to minimize the
ground source current and should be sized such that TOV is limited to a
ceiling of 150% of nominal voltage. Due to the addition of a ground source
to HONI‘s distribution system, an HVI will be required. This DGIT
configuration may require a grounding transformer (zig-zag) to be
connected on the LV side of the DGIT to limit the TOV on the LV side.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
43
Figure 7: Alternate DGIT configuration for 3-Wire Distribution System
Alternate Option #2
A Wye-ground:Wye-ground interconnection transformer on HONI‘s 3-Wire
distribution system as shown below in Figure 8 is also not a preferred
option, however it may be acceptable if required and will be determined in
the CIA. It is required to have a delta tertiary winding to limit the harmonic
distortion to HONI‘s distribution system.
A neutral reactor in the primary winding may be necessary and should be
sized such that TOV is limited to a ceiling of 150% of nominal voltage.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
44
Figure 8: Alternate DGIT configuration for 3-Wire Distribution System
3.1.12 High Voltage Interrupting Device (HVI)
The following are requirements for a HVI to be installed at the DG facility. This
device shall be sized properly to account for present and future anticipated fault
levels. The design shall be reviewed and accepted by HONI. If an HVI is not
required, a Low Voltage Interrupter (LVI) shall be installed on the low voltage side
of the DGIT.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
45
3.1.12.1 Requirement for Interconnection to 4-Wire Distribution System
A High Voltage Interrupter (HVI) with protection interface for tripping is
required for all DGs larger than 1 MVA connected to HONI‘s 4-wire
distribution system. This is required to remove the ground source (see
Section 3.1.11.1 for DG Interconnection Transformer Configuration) from
the distribution network following a fault to allow for proper protection
coordination. For DGs smaller than 1 MVA connecting through a Wye-
ground:Wye-ground DGIT, the HVI is optional (see Section 3.1.11.1,
Alternate #3).
3.1.12.2 Requirement for Interconnection to 3-Wire Distribution System
If the DG Interconnection Transformer preferred option (Section 3.1.11.2) is
chosen for HONI‘s 3-wire system, the HVI is optional, and the DG Owner
shall decide whether to install an HVI or not. If in the future, the
requirements change and an HVI will be required, the DG Owner will be
obliged to install one at its own cost. For all other alternate options for the
DG Interconnection transformer for HONI‘s 3-Wire distribution System, an
HVI will be required for DG Facilities.
3.1.12.3 Interrupting Time Requirement
When the HVI is the used to disconnect generation from HONI‘s distribution
system, it must not exceed the maximum interrupting time of 85ms (5
cycles).
3.1.13 Station Service for Critical Loads
A dedicated station service AC power source will be required to supply critical
loads (such as the station battery) whenever the HVI or LVI are OPEN. If the
station service AC service power source is obtained from either HONI or a local
distribution company, the DG owner must ensure that the above station service AC
power source cannot be electrically connected to the DG electrical system that is
associated with the power transfer from the DG facility to the HONI distribution
system (example: the intent is to prevent reverse power from the DG facility to the
station service AC supply source. The station service load shall not impose
operating restrictions on HONI‘s system when either the Motorized Disconnect
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
46
Switch (Load Break Switch) or the HVI is opened – generator is disconnected.
The station service shall comply with all required load connection standards.
3.1.14 Grounding
The DG facilities grounding (generators and interconnection) shall be per
manufacturer‘s recommendation and the OESC and follow the requirements set
out in this document (refer to Section 3.1.11, Interconnection Transformer
Configuration and Section 3.2, Protection requirements section).
The grounding of the DG facility must not cause overvoltages that exceed the
rating of equipment connected to HONI‘s distribution system. Refer to Section
3.1.5 for voltage requirements). The grounding of the DG facility must not disrupt
the coordination of ground fault protection of Hydro One‘s distribution system.
As discussed in Section 3.1.11, if the primary HV winding of the DG
Interconnection Transformer is grounded, the ground grid of the DG facility is to be
connected to HONI‘s ground grid (neutral). For 4-wire DG installations,
transformers configured Wye-Gnd:Δ or Wye-Gnd:Δ:Wye-Gnd (refer to Section
3.1.11 for allowable DG Interconnection Transformer configurations) may require a
neutral reactor or a grounding transformer. The reactor or grounding transformer
shall be sized as follows:
Sizing of Neutral Reactor and Grounding Transformer for Conventional
(Rotating) Generators
The neutral reactor, Xn or grounding transformer shall be sized by the
DG Owner and reviewed during the Connection Impact Assessment
based on a Thevenin Equivalent of the Positive and Zero Sequence
Reactance of the DG facility (example: at the Point of Connection with
the Point of Connection OPEN) that will result in:
1.5 ≤XDG 0
XDG 1≤ 2.5
to achieve an overall Thevenin Equivalent Positive and Zero Sequence
impedance at any point on the feeder with any or all DG sources and
HONI sources In-Service of:
2 <X0
X1 < 3 and
R0X1
< 1
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
47
Sizing of Neutral Reactor or Grounding Transformer for DGs with an
Inverter Interface
The neutral reactor, Xn or grounding transformer shall be sized by the
DG Owner and reviewed during the Connection Impact Assessment
based on a Thevenin Equivalent of the Zero Sequence Reactance of
the DG facility (example: at the Point of Connection with the Point of
Connection OPEN) that will result in:
X0 = 0.6 ± 10% p. u. and X0
R0 ≥ 4
where 1 p.u. is based on:
the total MVA rating of the DG Facility (sum of DGITs MVA
ratings) and high side kV rating of the DGIT(s) for Grounding
Transformer sizing.
the MVA and high side kV rating of the DGIT for Neutral
Reactors sizing.
Note: DGIT MVA rating assumed to be approximately equal to the
generation capacity. See Appendix B for calculation examples.
For 3-wire installations, where the same transformer configuration is chosen, the
reactor shall be chosen to provide a TOV ceiling of 150% nominal voltage.
In wind farm installations, to limit the exposure of lightning to HONI‘s distribution
system, the lightning protection at each wind tower must be electrically separated
from the DG facility – Ground grids of wind towers shall be separated from the DG
Station ground grid. This can be achieved by ensuring that the wind towers are
not bonded to the stations electrical grid.
The installation of a wind farm shall not increase the lightning transfer to HONI‘s
system. Stand alone studies are required to ensure that GPR meets step and
touch potential ESA requirements and must also be submitted to HONI.
Design Consideration
Ground grids of wind towers shall be separated from the DG Station ground
grid. This can be achieved by ensuring that the wind towers are not bonded to
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
48
the stations electrical grid. There are different ways to achieve this, such as
ensuring that the cables are not bonding the two systems together (can be
achieved by designing a span or section of the line overhead).
3.1.15 Fault Levels
The impact of DG interconnection facilities on existing equipment ratings, circuit
loading and fault levels must be assessed. X/R ratios and maximum short circuit
levels must be maintained within acceptable Distribution System design and
Transmission System Code (TSC) limits. The DG facilities must not increase the
fault levels beyond these limits. Any required changes to distribution system
equipment ratings must be assessed by Hydro One and paid for by the DG Owner.
3.1.16 Resonance Analysis
The design of the DG facility should include a careful examination of resonance.
Resonance can cause damage to HONI‘s distribution system, electrical equipment
of HONI‘s customers, and the electrical equipment at the DG facility. Analysis
should be conducted by the DG owner to evaluate the possibility of the following
resonance conditions and if there is a possibility of them, eliminate their harmful
effects:
Ferro-resonance in the transformer – operating information may be
provided to the DG Owner upon request (information on single phasing
possibilities)
Sub-synchronous resonance due to large rotating machines and/or
capacitor banks present on the distribution system
Harmonic resonance with other customer‘s equipment when capacitors
are added to HONI‘s distribution system
Information on HONI‘s distribution system for the purpose of this analysis can be
provided upon request. Resonance analysis should be submitted to HONI for
evaluation and review.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
49
3.1.17 Self-Excitation Analysis
If the DG being installed is an induction generator, studies shall be conducted to
assess whether there is a possibility of self-excitation. Information on HONI‘s
distribution system for the purpose of this analysis can be provided upon request.
Self-excitation analysis should be submitted to HONI for evaluation and review.
3.1.18 Islanding
Upon loss of voltage in one or more phases of the HONI distribution system, the
DG facility shall automatically disconnect from all of HONI‘s distribution line
ungrounded conductors prior to the reclosure of HONI protection equipment. Local
islanding detection is required and will be discussed in Section 3.2.15.
Intentional islanding is not allowed at this time.
3.1.19 Synchronization
The DG facility shall parallel with HONI‘s distribution system without causing a
voltage fluctuation at the PCC greater than ± 4% of the prevailing voltage level of
the distribution system at the PCC and meet the flicker requirements (Section
3.4.1.1).
The DG facility (synchronous and permanent magnet generators) shall remain in
synchronism with HONI‘s distribution system while operating in parallel to HONI‘s
distribution system. Synchronous generators, self-excited induction generators or
inverter-based generators that produce fundamental voltage before the paralleling
device is closed can only parallel with HONI‘s distribution system when frequency,
voltage, and phase angle differences are within the ranges given below in Table 3
at the moment of synchronization. For synchronous generators, an approved
automatic synchronization device is required if the plant is unattended (IEEE
device number 25) to ensure that the DG facility will not connect to an energized
feeder out of synchronism.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
50
Table 3: Resynchronization Requirements
Aggregate Rating of Generators
(kVA)
Frequency Difference
(Δ f, Hz)
Voltage Difference
(Δ V, %)
Phase Angle Difference
(̊Δ Φ, ̊ )
0-500 0.3 10 20
>500 – 1500 0.2 5 15
>1500 0.1 3 10 * Source: IEEE 1547
Induction generators and inverter-based generators that do not produce
fundamental voltage before the paralleling device is closed, and double-fed
generators whose excitation is precisely controlled by power electronics to produce
a voltage with magnitude, phase angle, and frequency that match those of the
distribution system may not require synchronization facilities. These types of
generators shall be tested to determine the maximum startup current. The results
shall be used, along with the Distribution System source impedance for the
proposed location, to estimate the starting voltage magnitude change and verify
that the unit will not cause a voltage fluctuation at the PCC greater than ± 4% of
the prevailing voltage level of the distribution system at the PCC and meet the
flicker requirements (Section 3.4.1.1). Induction generators may be connected and
brought up to synchronous speed by direct application of rated voltage provided
that they meet the requirement of voltage drop given above and/or they do not
exceed flicker limits at the PCC. Otherwise, other methods such as reduced
voltage starting or speed matching using the prime mover prior to connection must
be used to respect these voltage drop and flicker limits.
Any proposed synchronizing scheme must be submitted to HONI prior to
installation and must be able to accommodate automatic reclosing on HONI‘s
distribution facilities. For large DG facilities with multiple generator units,
staggering the generator reconnections to HONI‘s distribution system may be
required and will be coordinated with HONI. Refer to Section 3.2.19, Section
3.2.21 and Section 3.2.23 for further information.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
51
3.1.20 Insulation Coordination
The DG facility shall be protected against lightning and switching surges such as
voltage stresses. Temporary overvoltages may affect equipment, both on the
distribution system and the DG facility. Overvoltage protection usually includes
using station and line shielding against direct lightning strikes and surge arresters
for all wound equipment. The surge arresters are located as close as possible to
the equipment they protect. HONI‘s distribution system voltage ratings are shown
below in Table 4.
Table 4: Arrester Ratings
HONI Distribution System Voltage Arrester
MCOV Rating
System Phase
Voltage (kV)
Arrester MCOV (kV)
4.16 3
8.32 6
12.5 9
13.8 10
24.9 18
27.6 21
44 39 (intermediate
class)
3.1.21 Equipment Rating and Requirements
The generation facility interface equipment must be compatible with Hydro One
equipment design and ratings under all operating conditions. Considerations
include, but are not limited to:
Respecting equipment thermal loading limits
Impact of generation facility fault contribution on equipment rating
If power is able to flow in reverse direction, then all existing voltage
regulating and metering devices must be suitable for bi-directional flow.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
52
3.1.22 Operating Requirements
The following are a list of operating requirements for DGs interconnecting to Hydro
One Networks Inc. sub-transmission and distribution system:
Switching that involves manual operation of air break switches will
require all connected DG's to come off-line as directed by the
Connection Agreement and/or Controlling Authority.
Any source configuration which is not the ―normal‖ source will require all
DGs to be disconnected until such a time when the ―normal‖ supply has
been restored. Normal supply is defined as the supply configuration that
has been studied in the CIA.
Any temporary feeder parallels will require all connected DG's to come
off-line as directed by the OGCC.
Transfer Trip and DGEO communications required for DGs 1 MVA and
larger, connecting to HONI‘s distribution system at voltages greater than
20 kV.
Transfer Trip initiated for outages upstream of the feeder breaker must
be in place back to the generator (i.e. high side faults, bus differential).
For feeders with multiple feeder reclosers, 50% minimum feeder load
calculations shall identify remaining loading levels with reclosers in open
position.
No automatic reconnection to the system will be allowed unless:
There is always customer contact with the ability to immediately
disconnect from the system if requested by the OGCC (24 hours/7
days per week, or
OGCC has the ability to remotely disconnect DG customer from
the system, and
Feeder relay studies must be updated if circuit configuration is
materially altered. If the source changes from the configuration
studied in the CIA, the generator will not be allowed to reconnect.
Automatic Reconnection to HONI‘s distribution system shall be locked
out once voltage and frequency are not within operating ranges for a
period of 15 minutes on any phase
Legacy facilities need to meet this documents DG Requirements.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
53
3.1.23 Metering
Metering requirements vary with the type and intent of the generation facility.
Please consult the IESO Market Rules and the Distribution System Code Section 5
for details. Refer to Section 4 of this document for more information.
3.1.24 DG Facility Acceptance
The DG facility interconnecting to HONI‘s distribution system must have a
professional engineer licensed in the Province of Ontario declare (stamp and seal)
that the DG facility has been designed, tested and constructed in accordance with
the requirements of this document, HONI‘s site-specific requirements, prudent
utility practice and all applicable standards and codes. HONI shall receive and
review all designs from the DG Owner at the proper stage.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
54
3.2 Protection Requirements
3.2.1 General Requirements
Abnormal conditions in the DG facility and on HONI‘s distribution system require
that the DG facility respond and protect itself and HONI‘s distribution system. This
response contributes to the safety of HONI‘s and DG‘s personnel and the general
public and avoids damage to both DG facility‘s, HONI‘s and HONI‘s customer‘s
equipment.
The protection schemes shall be designed to detect the conditions presented in
this section of this requirements document including but not limited to:
Balanced and unbalanced faults (line to ground, line to line, three phase)
at the DG facility and HONI‘s distribution system (entire distribution
feeder that DG is connected to)
Abnormal frequencies
Abnormal voltages
Islanding Conditions
The protection schemes employed shall coordinate with HONI‘s distribution system
protections and shall be designed for current and anticipated future fault levels.
Dedicated communications may be required to facilitate timely clearing of faults.
All protection operations shall ensure that the generator(s) and all sources of
ground current are tripped within the required time from the start of the
disturbance. For DG facilities utilizing a Wye-Ground high side DG Interconnection
Transformer (refer to Section 3.1.11 Interconnection Transformer Configuration),
both the DGIT and the generators must be tripped within the required clearing time
(refer to Section 3.2.4).
All protection scheme proposals will need to be reviewed and accepted by Hydro
One Networks Inc.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
55
3.2.2 Hydro One Networks Inc. Distribution System Feeder Protection
HONI will provide to the DG Owner, upon request, all applicable information about
HONI‘s distribution system protection scheme on the feeder interconnecting with
the DG facility.
Information regarding HONI‘s protection system, including philosophy, can be
found in greater detail in Section 2.9
HONI‘s distribution system protections may need to be upgraded and/or replaced
to accommodate DG interconnections. This may have financial implications for the
DG Owner.
3.2.3 Sensitivity and Coordination
The DG facilities protection shall provide adequate sensitivity to detect and clear
all faults in the DG facility as well as HONI‘s distribution system. The design shall
coordinate with other HONI protection system devices at present and anticipated
future fault levels.
3.2.4 Protection Operating Times
The DG interconnection protection shall disconnect the DG facility from HONI‘s
distribution system within the required time as specified in the individual
requirements throughout this document – Example: For any phase and ground
faults a maximum of 500ms from inception of the fault condition and islanding
conditions. This time is measured from the start of the abnormal condition to the
time the DG will cease energizing HONI‘s distribution system. This is a maximum
clearing time and in certain instances, the clearing time may be more stringent.
HONI will determine this in the CIA.
Timing diagrams for different events are shown for reference in Appendix C.
If the DG facility is required to have a High Voltage Interrupter (refer to Section
3.1.12), there is a requirement to ensure that the DG Interconnection Transformer
is disconnected from HONI‘s distribution system under abnormal conditions.
Therefore, the protections shall trip both the generators and HVI and clear within
the required time. Refer to Section 3.2.20, ―Disconnection of DG Facilities‖, and
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
56
Section 3.2.21, ―Reconnection to Hydro One Network‘s System‖, for more
information.
3.2.4.1 Interrupting Time for Device Disconnecting Generation
The interrupting device used to disconnect generation from HONI‘s
distribution system must have maximum opening time of 85ms.
3.2.5 Interrupting Device Rating
All fault current interrupting devices shall be sized appropriately. Fault contribution
from both the DG facility and HONI‘s distribution system shall be used to
adequately size all fault current interrupting devices. HONI will provide present
and anticipated future fault contribution levels from HONI‘s distribution system.
The interrupting device used to disconnect generation from HONI‘s distribution
system must have maximum interrupting time of 85ms.
For DGs that have a time variant fault contribution characteristics, the
characteristics producing the highest fundamental component fault current shall be
used – synchronous and induction generators shall use sub transient reactance to
calculate fault contribution. Inverter based DGs typically contribute fault current
marginally higher than rated full load current (usually 1.2 to 1.5 times the rated
load current of the inverter for self-commutated designs and less for line-
commutated inverters). Depending on the design, the rotor of double-fed
asynchronous motors may be shorted by crowbar action in response to severe
faults causing the generator to behave like an induction generator.
3.2.6 High Voltage Interrupter (HVI)
NOTE: For the purpose of this document, the HVI will refer to interrupting devices
on HONI‘s side of the DG Interconnection Transformer – whether it is high voltage
or medium voltage.
DG facilities connecting on 4-Wire distribution systems are required to be equipped
with a High Voltage Interrupter (HVI) as can be seen in Figure 2, Figure 3, and
Figure 4 of Section 3.1.11.1. For DGs smaller than 1 MVA connecting through a
Wye-ground:Wye-ground DGIT, the HVI is optional (see Section 3.1.11.1,
Alternate #3).
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
57
DG facilities connecting on 3-Wire distribution systems are not required to be
equipped with a High Voltage Interrupter (HVI) if they connect using the preferred
DGIT configuration (Refer to Section 3.1.11.2). All ―Alternate‖ DGIT configurations
for 3-Wire connections require an HVI.
In the event that an HVI is required, it will be equipped with a protection interface
for Tripping. The HVI shall be sized according to the present and future
anticipated fault current. The HVI status should be monitored and ―Breaker Fail‖
initiated during every protection trip operation – See Section 3.2.7 for details on
Breaker Fail.
This requirement is driven by the DG Interconnection Transformer Configuration
and the need to remove the ground source from the distribution system before the
1st reclose to ensure that the DG facilities will not adversely affect overcurrent
protection devices on HONI‘s distribution system - the feeder and DG HVI will be
tripped for feeder faults or feeder islanding conditions (feeder breaker trips
instantaneously and independently of DG HVI tripping). Before the 1st reclose, all
the DGs and associated DGITs on the distribution feeder shall be disconnected
from the feeder. Upon reclose, the feeder 51 & 51N times overcurrent devices will
co-ordinate with reclosers and lateral fuses on HONI‘s distribution system since all
current infeeds from the DGs and DGITs are removed. The HVI is also required to
prevent backfeed whenever single phase switching can occur upstream of the DG
on HONI‘s distribution system Refer to Section 2.9 for more information regarding
HONI‘s distribution system protection practices and standards.
As the HVI trips, the generators shall trip (LVI or equivalent) and the HVI should
reclose back in within the first 30 seconds in the event of a successful reclose
operation on HONI‘s feeder – The first DG facility connected to the feeder shall
have the HVI reclose within 15 seconds of detecting voltage and frequency within
normal limits (refer to Section 2 for details on operating characteristics of HONI‘s
Distribution system). There may be a need to stagger multiple DG‘s DGITs
energization to minimize the effects of inrush on HONI‘s distribution system and
the resulting voltage sag and flicker (additional DG facilities shall be set between
15 seconds and 30 seconds). Refer to Section 3.2.21 for more information on
reconnection to HONI‘s system following a momentary and sustained outage and
Appendix C for timing diagrams.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
58
3.2.7 Breaker Fail (BF)
* Breaker Fail may refer to a breaker, HVI, LVI or any fault interrupting device failing.
Breaker Fail protection needs to be included in the DG facility‘s protection design
for both the High Voltage Interrupter and Low Voltage Interrupter to ensure that a
breaker/interrupter failure will not disrupt HONI‘s distribution system and/or the DG
facility by ensuring that faults are cleared in a timely fashion. A means of
automatic backup isolation is required to allow quick restoration of the distribution
feeder. The breaker failure protection should have a maximum pickup time delay
after initiation of 0.3s.
3.2.7.1 BF Protection for HVI
The DG facility protections shall provide breaker failure protection and trip
all LV breakers in the event of the HVI or primary interrupting device
failing to isolate the DG facility from HONI‘s distribution system. The
motorized disconnect switch (see requirements in Section 3.1.4) shall be
opened by a separate auxiliary relay in the event of a breaker fail
condition to ensure that the DG facility is properly isolated from HONI‘s
system.
In the case of a circuit switcher, the interrupter and the motorized
disconnect shall be specifically chosen to operate independently. In
normal operation, when the HVI isolates the facility, the motorized
disconnect switch will follow, opening a short period afterwards. It can
also be designed to open sequentially – motorized disconnect opens if
HVI does not OPEN following a trip initiation.
In the event of a breaker fail condition, the next zone at the DG facility will
be tripped via the Low Voltage Interrupter in the facility (LVI) and by
removing the prime mover and excitation system as appropriate. The
motorized disconnect switch (at the PCC) shall be used to automatically
isolate the DG facility from the distribution system. In the event that an
alternate interrupting means (fuses or otherwise) is not provided by the
DG facility or if such alternate interrupting means fail to coordinate with
the opening of the motorized disconnect switch, then the disconnect
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
59
switch may incur significant damage when attempting to interrupt a
sustained fault current condition as it is not rated for breaking fault current.
The design of the DG facility shall take this into consideration when
deciding on a location for the Point of Disconnect to ensure that safety of
the DG facility personnel, HONI‘s personnel and general public will be
ensured.
The design of the BF protection for the HVI shall be submitted to HONI for
review and acceptance.
3.2.7.2 BF Protection for LVI
In the event of the LVI malfunctioning, breaker fail protection is required to
ensure that a fault in the DG facility is cleared and will not affect the high
voltage system. Breaker fail should trip the HVI (and initiate BF on the
HVI) to ensure that the DG facility is isolated from HONI‘s distribution
system. For the DG facilities not equipped with an HVI, the motorized
disconnect switch (Load Break Switch) shall be opened to isolate the DG
facility from HONI‘s distribution system. In the event that an alternate
interrupting means (fuses or otherwise) is not provided by the DG facility
or if such alternate interrupting means fail to coordinate with the opening
of the motorized disconnect switch, then the disconnect switch may incur
significant damage when attempting to interrupt a sustained fault current
condition. The DG Owner shall take steps to ensure that the DG facility,
its equipment and personnel is protected.
3.2.8 Single Phase Generators
Single phase generator requirements are summarized below in Table 5. Inverter
type generators must be compliant with IEEE Std. 929 Recommended Practice for
Utility Interface of PV Systems and be certified to UL 1741 and CSA 22.2-107.1.
Figure 9 shows an example protection for single phase generators given for
information purposes only. The protection system can be designed differently.
The final design of the protection system shall be submitted to HONI for approval
as described in Section 3.2.36.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
60
Table 5: Typical Protections Required for Single Phase DG Facilities
Protection Description IEEE Device #
Interconnect Disconnect Device 89 Generator Disconnect Device
Over-Voltage Trip 59 Under-Voltage Trip 27
Over Frequency Trip 81O Under Frequency Trip 81U
Overcurrent** 50/51 Distance *** 21
Synchronizing Check* 25 Anti-Islanding Protection Refer to Section 3.2.15
Additional Protections May Be Required
* Only required for synchronous generators and other types which
have standalone capability ** Could be provided by magnetic circuit breaker or fuse *** Distance may be required to be able to detect faults along the
entire length of the feeder
Figure 9: Example Protection for a Single Phase Generator
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
61
3.2.9 Three Phase Generators
Three phase generator typical protection requirements are summarized below in
Table 6. Inverter type generators must be compliant with IEEE Std. 929
Recommended Practice for Utility Interface of PV Systems and be certified to UL
1741 and CSA 22.2-107.1.
Section 3.2.9.1 through to Section 3.2.9.3 (Figure 10-12) shows example
protections for three phase generators depending on the DGIT configuration
chosen for DGs connecting to HONI‘s 3-Wire distribution system. Section 3.2.9.4
through to Section 3.2.9.6 (Figure 13-15) shows example protections for three
phase generators depending on the DGIT configuration chosen for DGs
connecting to HONI‘s 4-Wire distribution system. The protection systems can be
designed differently and the examples shown in this document are for
informational purposes only. Additional protections may be required. Generator
protections are not the focus of this document and no requirements are set by
HONI. It is up to the DG Owner to ensure that the generators are protected
sufficiently. The final design of the protection system shall be submitted to HONI
for approval as described in Section 3.2.36. DG Interface Transformer
Configuration Requirements are located in Section 3.1.11.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
62
Table 6: Typical Protections for Three Phase DGs
Description Device HONI Distribution
System Protection
Anti-Islanding
Protection
Synchro-nization
DG Protection
X - Required O - Optional
Transfer Trip Receive TTR* X*
DGEO DGEO X*
Over-Voltage Trip 59 X X X X
Under-Voltage Trip 27 X X X X
Over-Frequency Trip 81O X X X X
Under-Frequency Trip 81U X X X X
Overcurrent 51 X X
Neutral Overcurrent 51N X X
Voltage Controlled Overcurrent
51V O O
Directional Overcurrent 67 O O
Directional Neutral Overcurrent
67N O O
Transformer Differential 87 O O Distance 21 O** O
Ground Distance 21N O** O
Ground Overvoltage 59N*** O O
Reverse Power 32 O O O
Negative Sequence Overcurrent
46 O O O
Negative Sequence Voltage
47 O O O
High Speed Overvoltage
59I*** O O
Synchronization Check 25 X
Loss of Excitation 40 O
Interconnection Disconnect Device
89 X X X
Generator Disconnect Device
X
* Transfer Trip and DGEO required where available generation is greater than 50% of minimum load, or where reclosure is less than 1 second, or if DG facility is rated at 1 MVA or higher – Refer to Section 3.2.16
** May be required if complete feeder coverage cannot be guaranteed for entire length of feeder
*** May be required if ferroresonance is expected
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
63
3.2.9.1 Delta:Wye DGIT Connecting to 3-Wire – Preferred
Figure 10: Preferred Connection for 3-Wire Distribution System
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
64
3.2.9.2 Wye-Gnd:Delta DGIT Connecting to 3-Wire - Alternate
Figure 11: Alternate Connection for 3-Wire Distribution System
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
65
3.2.9.3 Wye-Gnd:Delta:Wye-Gnd Connecting to 3-Wire - Alternate
Figure 12: Alternate Connection for 3-Wire Distribution System
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
66
3.2.9.4 Wye-Gnd:Delta DGIT Connecting to 4-Wire - Preferred
Figure 13: Preferred Connection for 4-Wire Distribution System
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
67
3.2.9.5 Wye-Gnd:Delta:Wye-Gnd Connecting to 4-Wire - Alternate
Figure 14: Alternate Connection for 4-Wire Distribution System
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
68
3.2.9.6 Delta:Wye DGIT Connecting to 4-Wire - Alternate
Figure 15: Alternate Connection for 4-Wire Distribution System
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
69
3.2.10 Phase and Ground Fault Protection Requirement
The DG facility‘s protection system must ensure that the DG facility will detect and
automatically isolate itself from HONI‘s distribution system for:
Internal Faults within the DG facility
External Faults within HONI‘s distribution system – the DG must detect
phase and ground faults along the entire distribution feeder that it is
connected to – including single phase lateral taps 2
The DG‘s protections must be capable of detecting the following conditions at the
DG facility and HONI‘s distribution system feeder which it is interconnected with:
Phase-to-Phase faults
Phase-to-Ground faults
Loss of any phase
HONI will provide the DG Owner the maximum impedance fault that the DG facility
is required to detect. The protective device selectivity and sensitivity have to be
maintained over the full range of minimum to maximum fault currents (present and
anticipated future levels) with the DGs infeed.
The total clearing time for faults on HONI’s distribution system or for faults
in the DG facility is to be no more than 500ms to coordinate with HONI’s
reclosure time. The clearing time is measured from the start of the abnormal
condition to the time that the DG facility ceases to energize HONI’s
distribution system.
DG facilities requiring an HVI due to the DGIT winding configuration must ensure
that phase and ground fault protection are always operational as long as the HVI is
closed – ground fault protection must be operational even if generators are out of
service. This is to ensure that the DGIT and resulting ground source will be
disconnected from HONI‘s system in the event of a fault and allow proper
overcurrent coordination.
2 Must see entire feeder for phase and ground faults – past reclosers/sectionalizers/fuses
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
70
A means of automatic backup isolation is required to cater for an HVI or LVI failure
condition. The automatic backup isolation is required to allow quick restoration of
the distribution system feeder following an HVI or LVI failure condition. The
motorized disconnect switch at the PCC shall be used to automatically isolate the
DG Facility from the distribution system. In the event that an alternate interrupting
means (fuses or otherwise) is not provided by the DG Facility or if such alternate
interrupting means fail to coordinate with the opening of the disconnect switch,
then the disconnect switch may incur significant damage when attempting to
interrupt a sustained fault current condition. All breaker fail protection designs
shall be submitted to HONI for review and approval (See requirements in Section
3.2.7).
All protective device settings and protection scheme designs must be submitted to
HONI for review. Over time, as the system configuration changes, settings may be
required to be changed to maintain adequate system protection.
Design Consideration
Standard overcurrent elements may not cover faults along the entire feeder
and may not coordinate with HONI‘s protection systems. Distance (21) type
protections may need to be considered. The settings for the distance
elements shall be determined by the DG Owner with the information provided
by HONI. The distance elements will be required to detect faults along the
whole feeder after HONI‘s protections operate and HONI disconnects. It may
be impossible for the DG protections to detect all faults over the whole feeder
prior to HONI disconnecting due to the apparent impedance before HONI‘s
protections trip. Due consideration must be given to apparent impedances
due to other DGs connected to the feeder.
3.2.11 Unbalance Protection
The DG facility is required to detect single phasing conditions (loss of phase) –
Refer to Section 3.2.10.
Design Consideration
The design of the DG facility should consider using an unbalance or negative
sequence relay that will trip the DG on excessive current unbalance, especially
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
71
if the DG is installed on a section of HONI‘s distribution system that utilizes
single phase tripping.
3.2.12 Feeder Relay Directioning
Existing overcurrent protections in HONI‘s distribution system have been designed
to clear phase and ground faults downstream of their location as HONI‘s
substation has been the one source feeding the fault. With the addition of DGs to
HONI‘s distribution system (additional sources), the fault contribution from these
DGs may cause HONI‘s protections to operate non-selectively for reverse faults.
Feeder relay overcurrent elements may trip for faults on adjacent feeders due to
the infeed from DGs on the feeder. To prevent this sympathetic tripping, the relays
may need to be directioned to be able to sense reverse fault current conditions.
Inline reclosers may also need to be directioned to ensure that faults upstream of
the reclosers will not cause the reclosers to operate due to the infeed from the
DGs. In addition, communication facilities between the TS and recloser may be
required as a result of DGs located downstream of the recloser to facilitate co-
ordinated tripping and reclosing.
The need to replace/update equipment on HONI‘s distribution system to enable
directioning of feeder protections will be specified to the DG Owner in the CIA.
3.2.13 Over Frequency/Under Frequency Protection
Over and under frequency protection is required at the PCC of the DG
interconnection (see OESC rule 84-014, IEEE Std. 1547 Clause 4.2.4, CSA Std.
C22.3 No.9-08). The DG facility interconnection protection scheme shall have the
capability of detecting abnormal frequencies and clearing within the times shown
below in Table 7. The DG facility must separate from HONI‘s distribution system if
these frequency deviations occur within the clearing time. The clearing time is
measured from the start of the abnormal condition to the time that the DG facility
ceases to energize HONI‘s distribution system. These clearing times are
maximum clearing times and may be required to be more stringent. This
information will be provided by HONI. For generators > 30 kW, the frequency set
points shall be field adjustable while for smaller generators, it may be fixed or field
adjustable.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
72
For generators > 30 kW, the lower frequency set points shall be set to comply with
the NorthEast Power Coordinating Council (NPCC), ―Directory D2‖, as seen below
in Figure 16 – adjustable Lower Frequency set point shall be set to follow the
attached graph.
The DG may reconnect after the distribution system is stabilized and the
requirements of this guide are met. For additional requirements related to
reconnection to HONI‘s distribution system refer to Section 3.2.21.
Table 7: Over/Under Frequency Protection Set Points and Clearing Times
Generator Size Frequency Range (Hz) Clearing Times(s)*
≤ 30 kW > 60.5 0.16 < 59.3 0.16
> 30 kW
> 60.5 0.16 < (59.8 – 57.0) -
adjustable Adjustable – 0.166
to 300 < 57.0 0.16
* Generators ≤ 30kW – Maximum clearing time Source: IEEE 1547
* Generators > 30kW – Default clearing time
Figure 16: NPCC Directory D2 Requirement
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
73
3.2.14 Overvoltage/Undervoltage Protection
Over and under voltage protection is required at the DG facility PCC (IEEE Std.
1547 Clause 4.2.3, DSC Appendix F.2 Section 6.5, CSA C22.3 No.9-08 Clause
7.4.7). The DG facility interconnection protection scheme shall have the capability
of detecting abnormal voltages shown in Table 8 and disconnecting the DG facility
from HONI‘s distribution system in the clearing times specified (voltage is to be
measured phase-neutral for single phase installations or grounded Wye-Wye
transformer configurations, otherwise phase-phase voltage shall be used). The
voltages shall be detected at the PCC.
The clearing time is measured from the start of the abnormal condition and the DG
facility ceasing to energize HONI‘s distribution system. These are maximum
clearing times and may be more stringent depending on the application. HONI will
provide these clearing times if different from the table. For DGs > 30kW, the
voltage set point shall be field adjustable and for smaller DGs, it can be fixed or
field adjustable. Undervoltage relays should be time-delayed to avoid
unnecessary tripping while over-voltage relays may be instantaneous. High speed
instantaneous voltage protection may be considered for detecting ferroresonance
and self-excitation conditions.
Table 8: Over/Under Voltage Protection Setting and Clearing Time
Voltage Range (% of base voltage) Clearing Time(s)*
V < 50 0.16 50 ≤ V < 88 2.00
110 < V < 120 1.00 V ≥ 120 0.16
* DG ≤ 30 kW – Maximum clearing time Source: IEEE 1547 * DG > 30 kW – Normal clearing time
The DG facility may reconnect after HONI‘s distribution system has stabilized and
requirements for reconnection in this document are met (refer to Section 3.2.21).
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
74
3.2.15 Anti-Islanding Protection
An electric island is a section of the distribution system which, when disconnected
from the rest of the HONI system, remains energized by DGs connected to the
feeders. Anti-islanding protection is required to:
Ensure that HONI customers do not experience power quality problems
Prevent out-of-phase reclosing between HONI‘s distribution system and
the DG facility
Reduce the risks of safety hazards caused by islanding
Add redundancy to other protections
At the present time, HONI will not allow islanded operation. Upon loss of voltage
in one or more phases of HONI‘s distribution system, the DG facility shall
automatically disconnect from all of HONI‘s ungrounded conductors prior to
reclosure. Reclosure times will be provided to the DG owner and are usually
between 1.0s and 2.0s.
Anti-islanding protection may involve different protection functions. Each DG
interconnected to HONI‘s system, shall contain this protection and must
demonstrate that the DG facility will not sustain an island longer than permitted. In
certain installations, the installation of dedicated communications (transfer trip) and
protection schemes may be required for anti-islanding protection and is discussed
in Section 3.2.16. Appendix D has detailed information on Anti-Islanding
Protection and discusses the different requirements for Transfer Trip. Please refer
to this appendix for more information. Induction generators, due to the possibility
of self-excitation, also have this requirement.
The DG facility, instead of using transfer trip for anti-islanding protection may use
an approved Hydro One Networks Anti-Islanding Protection Scheme. At present,
there are tests being conducted and if and when any of these schemes is
approved by HONI to meet anti-islanding protection requirements, they will be
posted in this section in a future revision.
To facilitate DG interconnections of 500kW and less, passive Anti-Islanding
protections, specifically Rate of Change of Frequency and Vector Jump or Reverse
Reactive Power, may be considered as an interim solution until an approved low-
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
75
cost failsafe solution is finalized (ENERPULSAR pilot projects currently underway
– pulse based anti-islanding protection) These special considerations for DGs less
than 500kW have been made to enable these generators to connect with the
associated risks of passive anti-islanding technologies without having to wait for an
approved standardized solution.
It is in the DG Owners interest to make certain that the anti-islanding protection is
operational and will operate under all conditions with no non detection zone (NDZ)
as the DG Owner will be responsible for the damage to the DG facility that can
occur during out-of-phase reclosing.
3.2.16 Requirement for Transfer Trip
A Transfer Trip (TT) signal from the upstream feeder breaker/recloser to the DG
facility is required for any or all of the following conditions:
When the aggregate DG facility capacity is more than 50% of the
minimum feeder load, or
When the aggregate generation capacity on the feeder is more than 50%
of the minimum feeder load, or
When the aggregate DG facility capacity is 1 MVA or larger
If the existing reclosing interval time delay setting is short (dead time),
typically less than 1.0s
If any of the above requirements are met, then the DG facility shall cease to
energize HONI‘s distribution system after receiving a transfer trip signal. The DG
Facility is also responsible to make certain that upon transfer trip communication
loss, the DG facility will trip within 500ms for ―wired communications3‖ and within 5
seconds for wireless communications. The interrupting device used to disconnect
generation from HONI‘s distribution system must have maximum opening time of
85ms (time to open after receiving Transfer Trip signal from HONI).
3 Communications medium is wired, such as leased circuits, fibre, etc.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
76
3.2.16.1 Possible Exemption for DGs Smaller than 500kW
To facilitate DG interconnections of 500kW and less, passive Anti-
Islanding protections, specifically Rate of Change of Frequency and
Vector Jump or Reverse Reactive Power, may be considered as an
interim solution until an approved low-cost failsafe solution is finalized
(ENERPULSAR pilot projects currently underway – pulse based anti-
islanding protection) These special considerations for DGs less than
500kW have been made to enable these generators to connect with the
associated risks of passive anti-islanding technologies without having to
wait for an approved standardized solution.
3.2.17 DGEO (Distributed Generator End Open)
Hydro One Networks requires a Distributed Generator End Open (DGEO) signal
from the DG facility whenever transfer trip is required (see Section 3.2.16) to
confirm that the generator end has opened. Hydro One uses the DGEO signal for
the auto-reclose supervision of the TS feeder breaker or any upstream protective
device. This is to ensure that the DG facility HVI/LVI has opened and there is no
risk of out-of-phase reclosing. A combination of HVI and/or LVI status may be
used to key the DGEO signal. At the DG end, the DG is required to provide the
feeder protection with one signal that takes into account the Low Set Block Signal
(Refer to Section 3.2.22 ―LSBS (Low Set Block Signal)) and the DGEO signal.
This dual function signal will be set to ‗1‘ when the breaker is open and set to ‗0‘ 1s
prior to the energization of the DGITs to allow temporary blocking of the upstream
protections to avoid mis-operations due to large inrush currents. Timings for
these signals and ―Design Considerations‖ can be found in Appendix E.
3.2.18 Unintentional Energization
The DG facility shall not be capable to energize HONI‘s distribution system when
the distribution system is de-energized.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
77
3.2.19 Connection to Hydro One Network’s System
The DG facility connection is restricted only to the ―normal‖ supply configuration.
The normal feeder supply configuration is considered to be when the feeder is
supplied from one TS feeder breaker (the normal supply breaker) and all normally
open line switches are open, as defined by Hydro One operating diagrams.
The CIA will clearly identify the ―normal‖ feeder supply configuration that was
studied and was determined to be acceptable for connection.
Alternate (abnormal) supply configurations may be required from time-to-time to
circumvent contingency situations (equipment failures, maintenance, upgrading
and repairs). Under such circumstances the DG facility must be disconnected.
Alternate feeder supply configurations are considered to be in effect when the
feeder section to which the DG is connected is supplied from other than the
―normal‖ Hydro One TS feeder supply breaker or if any of the normally open
feeder-end switches are closed extending the feeder, as shown on the operating
diagrams. Although other supply configurations may be of concern, the expected
most common alternate feeder supply configurations that will not facilitate DG
connection are as follows:
Back-up supply of load customers from the adjacent TS feeder breaker
(TS feeder tie switch closed)
Back-up supply of load customers from another TS
Extending supply to load customers connected to an isolated section of
an adjacent feeder normally supplied from another source by closing a
normally-open feeder-end switch
Different conditions need to be met before reconnecting to HONI‘s system,
depending if the outage is a momentary outage or sustained outage or shutdown.
They are explained below. Automatic Reconnection of the DG facility to HONI‘s
system is subject to specific requirements which can be found in Section 3.2.21
and Section 3.2.23.
3.2.20 Disconnection of DG facilities
The following steps need to be taken to disconnect the DG facility from HONI‘s
distribution system during abnormal conditions or upon the receipt of a TT signal.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
78
3.2.20.1 Disconnecting DG Generation
For the first occurrence of a fault on any portion of the faulted feeder,
Hydro One high-speed sensitive ―low set‖ protection should operate to
isolate the Hydro One supply from the fault. The DG generation must
also be disconnected without delay to disconnect the DG supply from the
fault, to ensure fault extinction, to avoid any sustained DG island
condition and to avoid interference with normal Hydro One supply
restoration using automatic reclosure.
Disconnection of DG generation will be accomplished by TT and/or DG
interface protection as outlined in Section 3.2. The DG generation will be
disconnected using the same LV devices that were used to synchronize
the generation to the Distribution System (or by opening the HVI if the
LV devices fail to disconnect). Wherever HV ground sources are
present, additional steps listed in Section 3.2.20.2 are required.
3.2.20.2 Disconnecting DG HV Ground Sources
As per Section 3.1.11 above, any DG connections that have a HV
ground source and a HVI must ensure that the ground sources will be
disconnected whenever TT is received or DG Interface protection
operates, as outlined in Section 3.2 above, by opening the HVI.
3.2.21 Reconnection of DG Facility
The DG facility cannot operate connected to any part of the Distribution System in
island mode. The DG cannot reconnect until the Distribution System feeder has
been successfully energized from the normal Hydro One source.
3.2.21.1 Reconnection of Hydro One Source (for a transient fault4)
This is not a requirement, however it outlines what must take place
before the DG can reconnect. Refer to Appendix F for a detailed
sequence of events and timing diagram.
Following the first protection operation, the Hydro One feeder breaker or
recloser will be automatically reclosed to quickly restore supply to load
4 Generally associated with a momentary outage - loss of supply is less than 15 minute
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
79
customers. Typical reclosing times are 0.5 to 1 second for feeder
breakers and 1.5 to 2 seconds for reclosers.
The Hydro One low-set instantaneous (fuse-saving) protections are
always blocked when the feeder is re-energized. Blocking the low-set
protections prevents an immediate re-trip caused by high energization
current associated with transformer inrush and cold-load effects. Only
the Hydro One high-set and time-coordinated protections are available at
the time of Hydro One reconnection. The high-set and timed protections
are coordinated with feeder reclosers and fuses to provide selective
isolation of faults on the feeder. Should a fault be established at the time
of feeder energization, these protections will operate as required to
isolate only those sections of the feeder required to clear the fault,
allowing service to be restored to the un-faulted sections.
Approximately 10 seconds after a successful automatic reclose
operation, all Hydro One feeder protections should be restored to their
normal state (complete with the low-set protections enabled).
3.2.21.2 DG Facility Reconnection
Reconnection to Hydro One Networks distribution system is a two step
process as outlined below for DG Facilities equipped with a required
HVI5 DG facilities not requiring a HVI only need to follow Step 2. Step
1 and Step 2 can occur simultaneously if the DG has facilities for
synchronizing the generation via the HVI.
Step 1: DGIT Re-Energization
For DG Facilities not requiring a HVI, this step can be ignored.
Where a DG HVI was used to disconnect the DGIT, and the HVI is not
used for synchronizing generation, the first step in reconnecting the DG
is to close the HVI. However the DGIT must not be re-connected until
after the feeder has been successfully re-energized from Hydro One
source and the Hydro One feeder protections have been restored to
their normal state (10 seconds there-after). To ensure this, the DG HVI
can be allowed to automatically reclose only after voltage and frequency
5 Provision of an HVI is dependent on DG Interface Transformer winding configuration – Refer to Section
3.1.11.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
80
are restored within normal limits for a period of 15 seconds (refer to
Section 2 for details on operating characteristics of HONI‘s Distribution
system). Note: feeder reclosers may have multiple reclose attempts to
allow sectionalizers to operate to clear the fault. The 15 second
restoration period begins after the final successful reclose. Therefore,
restoration time delay should reset every time the feeder is de-
energized.
For DGIT with large transformer in-rush current, the sensitive Hydro One
low-set instantaneous protection may need to be temporarily blocked to
prevent re-tripping of the feeder when re-energizing the DGIT. In those
cases, just prior to re-energizing the DGIT, the DG facility will need to
alter the DGEO signal momentarily to provide a signal to the Hydro One
location that the low-set protection needs to be blocked. (Refer to
Section 3.2.22 for LSBS requirement).
There may also be a need to stagger the re-energization of multiple
DGITs, to minimize the effects of inrush on HONI‘s distribution system
and the resulting voltage sag and flicker. The HVI closing delay can be
set between 15 seconds and 30 seconds – HONI to coordinate the
staggered timing. The generators shall stay disconnected during this
time.
Step 2: Generator Reconnection
Following a disturbance to HONI‘s distribution system, no reconnection
may take place until HONI‘s system voltage is within 6% of nominal and
the frequency is between 59.5Hz and 60.5Hz.
The generation facility‘s interconnection system must include an
adjustable delay that may delay the reconnection for 5 minutes after
Hydro One‘s steady state voltage and frequency are restored to the
normal operating ranges identified above, following a momentary
outage. The reconnection of multiple DG units on a feeder may require
being staggered.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
81
Reconnecting generation is most typically done using LV synchronizing
facilities. If synchronization occurs via the HVI, Step 1 and Step 2 occur
simultaneously.
For DG facilities not equipped with a HVI, there may be a requirement to
send out a Low Set Block Signal prior to closing of the disconnect switch
to energize the DGIT. Refer to Section 3.2.22 for LSBS requirements.
Automatic reconnection is not allowed for outages longer than 15
minutes. HONI‘s operators must give permission before reconnection
occurs.
Additional requirements listed in Section 3.2.23 ―Auto-
Resynchronization/Reconnection‖ need to be met for this automatic
reconnection following a momentary outage to occur.
3.2.21.3 Lock-Out of Hydro One Source (For a Permanent Fault)
This section outlines what occurs on HONI‘s distribution system during a
permanent fault condition. Refer to Appendix F for a detailed sequence
of events and timing diagram.
If a fault re-occurs after a reclose attempt, the affected section of HONI‘s
distribution system shall be tripped again. Automatic reclosure will then
be inhibited and Hydro One supply will have to be manually restored.
Some protective devices have as many as four reclose attempts before
reclosing is locked out.
Manual restoration of the feeder will be attempted by the Hydro One
controlling authority. That may occur within a few minutes where remote
control is available. If a remote-controlled manual restoration attempt is
successful, and within 15 minutes of the loss of supply, then DG
reconnection can proceed as per Section 3.2.21.2 above. Otherwise a
sustained outage or shut-down will be necessary (greater than 15
minutes).
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
82
3.2.21.4 Restoration Following a Sustained Outage or Shutdown
No automatic reconnection of the DG facility may occur following a
sustained outage or shutdown – when the voltage and/or frequency out
of normal operating range on any phase for more than 15 minutes.
Permission to reconnect must be given by HONI‘s operators.
3.2.22 LSBS (Low Set Block Signal)
To ensure that the energization of the DG Interconnection Transformer following a
sustained outage or shutdown does not cause the Low Set Instantaneous
protections at HONI‘s feeder breaker to operate, a Low Set Block Signal (LSBS)
needs to be sent to HONI‘s feeder protections.
At the DG end, the DG is required to provide the feeder protection with one signal
that takes into account the Low Set Block Signal (Refer to Section 3.2.22 ―LSBS
(Low Set Block Signal)) and the DGEO signal. This dual function signal will be set
to ‗1‘ when the breaker is open and set to ‗0‘ 1s prior to the mechanical closing of
the HVI, or motorized disconnect switch, such that the feeder protection can
recognize the change of status and block the low-set instantaneous prior to the
energization of the DG Interface Transformer. Timings for these signals and
―Design Considerations‖ can be found in Appendix E.
This is a requirement wherever Transfer Trip and DGEO are required.
3.2.23 Auto-Resynchronization/Reconnection
Following a disturbance on HONI‘s distribution system, no reconnection may take
place until HONI‘s distribution system voltage and frequency are in the ranges
allowed in Section 3.1.5 and 3.1.7 respectively.
Auto-resynchronization/reconnection may occur if agreed by HONI for momentary
outages (distribution system voltage and frequency out of range for less than 15
minutes). The DG facilities interconnection system must include an adjustable
delay (from 5 minutes to 60 minutes after HONI‘s distribution system stabilizes)
that may delay the reconnection to HONI‘s system. HONI may coordinate the
restart time settings of DGs on the feeder in order to stagger the restarts and
minimize the effects of inrush to HONI‘s customers from the DG facilities upon
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
83
energization. Refer to Section 3.2.21 for more information on the steps required to
automatically reconnect to HONI‘s distribution system. Appendix F contains
detailed sequence of events and timing diagrams for informational and design
consideration purposes.
HONI requires to have the ability to prevent auto-resynchronization/reconnection if
operating deems necessary. Auto-resynchronization/reconnection shall be locked
out once voltage and frequency are not within operating ranges for a period of 15
minutes on any phase.
No automatic reconnection to HONI‘s distribution system will be allowed unless:
There is always customer contact with the ability to immediately
disconnect from the system if requested by HONI (24 hours/7 days per
week, or
HONI has the ability to remotely disconnect and lockout the DG customer
from the system, and
Feeder relay studies must be updated if circuit configuration is materially
altered. If the source changes from the configuration studied in the CIA,
the generator will not be allowed to reconnect.
3.2.24 Synchronization Protection
Any DG facility that is capable of generating its own voltage while disconnected
from HONI‘s distribution system shall require proper synchronization facilities
before connection is permitted. Interconnection shall be prevented if the DG and
HONI‘s distribution system is operating outside the limits specified in Section
3.1.19.
3.2.25 Telemetry and Targeting
The DG facilities protection schemes shall have systems in place to record and
provide upon request to HONI an electronic record of protective device operations,
or failures to operate. Refer to Section 3.3.4 for additional requirements.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
84
3.2.26 Transformer Protection
Design Consideration
Zero sequence currents circulating in the delta of a Wye-Delta transformer
during certain load and fault conditions are inevitable and if sustained, may
cause damage to the transformer. The design of the DG facility may require
transformer protection to prevent damage due to this phenomenon.
3.2.27 Protection from Electromagnetic Interference (EMI)
The DG interconnection system must have the capability to withstand
electromagnetic interference (EMI) environments in accordance with ANSI/IEEE
Std. C37.90.2, ―IEEE Standard for Withstand Capability of Relay Systems to
Radiated Electromagnetic Interference from Transceivers.‖ The influence of EMI
must not result in a change in state or misoperation of the DG facility – EMI must
not result in failure, misoperation or provide inaccurate information from the
protection, control and communication functions of the interconnection system.
The DG Owner shall provide documentation of compliance.
3.2.28 Surge Withstand Performance
The interconnection system must have the capability to withstand voltage and
current surges in accordance with the environments defined in IEEE/ANSI Std.
C62.41.2, ―IEEE Recommended Practice on Characterization of Surges in Low-
Voltage (1000 V and Less) AC Power Circuits‖ or IEEE Std. C37.90.1, ―IEEE
Standard for Surge Withstand Capability (SWC) Tests for Relays and Relay
Systems Associated with Electric Power Apparatus – Description.‖
The protection, control and communication equipment of the interconnection
system shall not fail, misoperate, or provide misinformation due to voltage or
current surges. CSA Std. C22.3 No.9-08, ―Interconnection of Distributed
Resources and Electricity Supply Systems,‖ provides more detailed information.
3.2.29 Special Interconnection Protection
Other protection not specified in this requirements document may be required
depending on the application. The DG Owner needs to be aware of site specific
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
85
conditions and the nature of HONI‘s distribution system to properly assess the
need for additional protections.
3.2.30 Batteries/DC Supply
The DG facility requires a reliable power supply for its protections to function.
Batteries shall be provided and shall have adequate capacity to ensure that all
protection functions operate when the main source of power fails. They shall
remain operational for the time required for protection functions to operate properly
and disconnect the DG facility from HONI‘s distribution system. This source can
be achieved by using batteries and chargers connected to the main service supply
or by using an uninterruptable power supply with sufficient capacity for the
application. The battery voltage shall be monitored and upon failure, the protection
scheme shall be considered failed and DG facility shall be disconnected from
HONI‘s distribution system.
The following design criteria shall be considered:
The relays connected to the DC supply must not be subjected to
sustained overvoltages – if there is a possibility that the DC rating of the
equipment will be exceeded, steps shall be taken to ensure that DC
voltage limiting devices be installed at each relay
Dual station batteries will not be required for protection and control
equipment.
Protection systems designed to back each other up, will be supplied by
physically separated and protected DC supplies.
Circuit breakers and HVI‘s shall be powered by separate and dedicated
DC supplies.
Separate and independent means are to be used for tripping the HVI
and motorized disconnect.
Upon low voltage condition, the protections shall trip the generators and
open the HVI.
Capacitors shall not be used as the primary means to store energy in lieu of
batteries.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
86
3.2.31 Protection Scheme Failure
The DG facility must promptly disconnect (without delay) from HONI‘s distribution
system and notify HONI‘s system operators if the interconnection protection
system fails, breaker trip coil fails or if DC supply is lost. The breaker(s) must
remain open until such a time when the affected system is returned to normal
service condition and the DG facility is safe for reconnection to HONI‘s system.
The DG Owner shall provide evidence to HONI that the design of the DG facility is
sufficient to mitigate the risks associated with protection scheme failure by using
self-diagnostic features (available with IEDs), redundancy or a fail-safe design.
The availability (health) of the TT and DGEO signals, the DG self-clearing
protection, the DG breaker and the associated power supplies must be
continuously monitored by the DG and all DG sources of energy to the distribution
system must be immediately disconnected or disabled if any facilities fail or
become disabled. The design of the protections at the DG facility shall be done by
a qualified professional engineer to ensure that the overall protection scheme will
ensure a safe and reliable interconnection to HONI‘s distribution system.
Malfunctioning, self-diagnosing relays, shall notify operating personnel, and if no
redundancies are in place, shall disconnect the DG facility from HONI‘s distribution
system until the malfunction has been repaired.
In designs where self diagnostic features do not trip the appropriate breakers upon
failure, sufficient backup and/or redundancy protections shall be provided. If
electro-mechanical relays are used, the protection and control design shall be of a
fail-safe nature to ensure the integrity of the protection scheme under
malfunctioning conditions.
3.2.32 Teleprotection Scheme Failure
3.2.32.1 Transfer Trip Channel Failure
In the event of the transfer trip communication channel failing, the DG
facility shall disconnect from HONI‘s system within 500ms for wired
communications, such as fibre and leased circuits, and within 5s for
wireless communications. The DG facility protection design shall ensure
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
87
that the teleprotection system is failsafe and that upon loss of transfer
trip, it will automatically trip the facility. The DG facility shall remain
disconnected until the transfer trip channel is repaired.
3.2.32.2 DGEO Channel Failure
In the event that the DGEO (refer to Section 3.2.17) communication
channel fails, HONI will block its feeder reclosing until the channel is
repaired. To maintain the reliability of the system for HONI‘s customers,
HONI reserves the right to send transfer trip to the DG and trip the DG in
order to allow automatic reclosing on its feeders. The DG Owner shall
ensure that repairs are conducted as quickly as possible.
3.2.33 Generators Paralleling for 6 Cycles or Less (Closed Transition Switching)
DG facilities paralleling for 6 cycles or less shall have the following protections:
Under-voltage protection to ensure that the generator is not capable of
energizing HONI system if it is de-energized
A 6 cycle timer to ensure that the DG will not parallel with HONI‘s
distribution system for more than 6 cycles.
Synchronization facilities, where required, must follow the requirements
specified in Section 3.1.19
The generator will be exempt from all other requirements of this document.
3.2.34 Instrument Transformers for use in Protection Systems
All instrument transformers used in DG facilities for protections shall meet the
requirements of IEEE C57.13 or CSA-C60044-6.
3.2.35 Provision for Future Changes
The DG Owner shall be responsible to stay aware of future changes to the
business environment and technical requirements and make any necessary
changes to its facilities. If HONI advises the DG Owner of required changes, the
DG Owner will make changes to the DG facility. The DG Owner is responsible for
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
88
making any changes to the DG facilities in response to meeting new or revised
standards or due to HONI distribution system changes. Therefore it should make
any provisions to accommodate changes efficiently. The DG Owner may be
responsible for the costs associated with these changes, including changes that
originated at HONI‘s request.
3.2.36 Interconnection Protection Acceptance
The DG Owner must provide Hydro One Networks Inc. with complete
documentation on the proposed interconnection protection scheme with:
a detailed Single Line Diagram
overall description on how the protection will function including during
failure modes
details on protection components such as manufacturer and model #
the protection component settings (pickup, timers, etc.)
details on monitoring for the protection system and recording protection
operations/misoperations
details on the disconnecting and interrupting device
This information will be reviewed by HONI against the requirements of this
document and all applicable standards for the potential impacts to HONI‘s
distribution system. If HONI proposes any changes, the DG Owner must revise
and re-submit the protection information to HONI.
All documentation must be submitted together. The latest submissions will be filed
by HONI and MUST MATCH the documentation retained by the DG Owner.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
89
3.2.37 Protection Summary
This document discusses the common protection required for DG interconnection
to HONI‘s distribution system. The minimum required interconnection protections
are:
Over-Voltage
Under-Voltage
Over-frequency
Under-frequency
Overcurrent/Distance protection
Anti-Islanding Protection
Other protections may be required depending on the application. All protection
designs must ensure proper coordination with HONI‘s protections, be failsafe and
ensure that both the DG and HONI‘s distribution system, customers and general
public safety are maintained.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
90
3.3 Control and Telecommunications Requirements
3.3.1 General
Control and telecommunications facilities will be required at customer facilities
connected to the Hydro One transmission and distribution system for provision of
protection and real time operating data. The Customer shall provide battery
backup for telemetry in the event that the facility is removed from the HONI
transmission or distribution system. Battery backup capacity shall be sufficient for
the connection to be re-established. Alternatives to battery backup are subject to
approval by HONI.
Under the TSC6, DSC and terms of this document, owners of generating stations
connected to HONI‘s transmission and distribution facilities have an obligation to
provide real time data pertaining to their equipment as required by the capacity at
the PCC. Monitoring and control may be required as a result of Renewable Energy
Supply Integration initiatives regardless of the capacity as will be determined by
HONI. Installation capacity descriptions shall be consistent with the class
definitions of IEEE 1547.3 which has been included here in Table 9 for
convenience.
Table 9: DG Classification
Class Generation Capacity at PCC
1 0 kW < DG rating < 250 kW 2 250 kW ≤ DG rating < 1500 kW 3 1.5 MW ≤ DG rating ≤ 10 MW 4 10 MW < DG rating
These requirements for real time operating information apply to all customer-
owned generating stations connected to HONI‘s transmission or distribution
network. The quantities and device statuses, defined below, shall be provisioned,
monitored and controlled for continuous transmission to HONI. Such details are to
be captured in Schedule I of the Customer‘s TCA, or an appendix in the DCA as
required by HONI and the applicable codes.
6 TSC Appendix 1, Schedule E, Section 1.6
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
91
3.3.2 Control Facilities
Subject to the agreement between the customer and Hydro One, all or some of the
following remote controls shall be provided to Hydro One:
(i) Station breakers and switchers
(ii) Motorized disconnect switches
(iii) Transformers‘ ULTC
(iv) 3% and 5% voltage reduction
(v) Hold off on feeder breakers
(vi) Dynamic generator output control
(vii) Other location specific devices
At any time, one and only one operating authority shall have remote control of the
station.
Where the customer maintains an operating centre and control of the station is
handed off from the customer to Hydro One at scheduled times, Hydro One will
consider the use of an ICCP link between the two control centres.
3.3.3 Telecommunication Facilities
Customers can provide real time operating information to HONI directly from the
station(s) or from the customer‘s SCADA master, as described below.
The customer shall provide the GPS coordinates of the facility to assist in the
evaluation of wireless communication alternatives.
The customer will provide all the required hardware and software and make
arrangements, as needed, with a commercial provider of communication services
to deliver the operating data to the demarcation point. Each DG Owner will be
responsible for all costs, initial and ongoing, and maintenance of their equipment
and communication circuits up to the demarcation point.
(a) From the IED at the customer‘s station to HONI‘s control centre using
serial DNP 3.0 protocol as follows:
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
92
(i) to HONI‘s wireless cellular data hub site and through the gateway to
HONI‘s control centre, with the demarcation point being inside
HONI‘s hub site.
(ii) where (i) is not feasible, to HONI‘s communication hub site and
through the gateway to HONI‘s control centre, with the demarcation
point being inside HONI‘s hub site
(iii) where (i) and (ii) are not feasible, to a HONI HV station and through
the RTU or gateway to HONI‘s control centre, with the demarcation
point being inside HONI‘s station
(iv) where (i) through (iii) are not feasible, through a Frame Relay
Network of a common carrier to HONI‘s control centre, with the
demarcation point being the CO nearest to the customer‘s station
(v) where (i) through (iv) are not feasible, HONI will suggest
communication circuit options available for a particular site.
Where modems will be used in any of the above communication methods,
HONI will determine the modem type and requirements considering
communication media, site location, reliability, and amount of data transfer.
(b) From a SCADA master through a Frame Relay Network to HONI‘s SCADA
master using ICCP. The communication demarcation point will be the CO
of a common carrier.
3.3.3.1 Reliability Requirements
The delivery of the real time data at the communication demarcation point
shall have unplanned failure rates and repair times as described in the
table below:
Table 10: Unplanned Telecommunication Failure Rates and Repair Times
Failure Mean Time to Failure
Mean Time to Repair
Failure to deliver data from a single station
4 years 24 hours
Simultaneous failure to deliver data from 2 to 5 stations
5 years 4 hours
Simultaneous failure to deliver data from more than 5
stations 20 years 4 hours
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
93
Prior to connection to HONI facilities, the customer shall submit a reliability
evaluation report which demonstrates that the above reliability
requirements can be satisfied.
The customer must coordinate any planned interruption to the delivery of
real time data with Hydro One.
3.3.4 Operating Data, Telemetry and Monitoring
In addition to the requirements in the sections of the TSC listed below, the
following additional requirements apply:
Real-time data to be provided to HONI by the customer:
3.3.4.1 Class 1 Generators
Generating facilities with a capacity of less than 250KW shall have
provision for monitoring the disconnecting device at the PCC.
Provisions for other quantities may be required and shall be determined by
HONI.
3.3.4.2 Class 2 Generators
Generating facilities with a capacity of greater than or equal to 250KW but
less than 1500KW shall provide the following information:
A) Analogue Quantities
(a) Net active power (MW) output and reactive power (MVAR)
flow and direction for each unit or total for the facility
(b) Phase to phase or phase to neutral voltages
(c) Three phase currents
B) Device Statuses
(a) All LV breakers/circuit switchers at the PCC
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
94
(b) AVRs and PSSs that impact the distribution system
(c) All generation rejection selections
C) Alarms
Provision shall be made for an alarm signal to be generated and
transmitted to HONI for transfer trip/DG end open (DGEO), loss
of communication (protection schemes) and loss of customer
owned interface protection (failed and disabled). A separate
alarm must be provided for each circuit supplying the customer.
The alarms shall identify the name of the customer facility and
the designation of the affected circuit. HONI shall determine
requirements based on controlling authority and equipment
ownership.
Monitoring and control may be required as a result of Renewable Energy
Supply Integration initiatives regardless of the capacity as will be
determined by HONI
3.3.4.3 Class 3 Generators
Generating facilities with a capacity of greater than or equal to 1500KW but
less than 10MW shall provide the following information:
A) Analogue Quantities
(a) Net active power (MW) output and reactive power (MVAR)
flow and direction for each unit or total for the facility
(b) Phase to phase or phase to neutral voltages
(c) Three phase currents
B) Device Statuses
(a) All LV breakers/circuit switchers at the PCC
(b) AVRs and PSSs that impact the distribution system
(c) All generation rejection selections
C) Alarms
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
95
Provision shall be made for an alarm signal to be generated and
transmitted to HONI for transfer trip/DG end open (DGEO), loss
of communication (protection schemes) and loss of customer
owned interface protection (failed and disabled). A separate
alarm must be provided for each circuit supplying the customer.
The alarms shall identify the name of the customer facility and
the designation of the affected circuit. HONI shall determine
requirements based on controlling authority and equipment
ownership.
Monitoring and control may be required as a result of Renewable Energy
Supply Integration initiatives regardless of the capacity as will be
determined by HONI
3.3.4.4 Class 4 Generators
Generating facilities with a capacity of greater than 10MW shall provide the
same data as identified for Class 3 generators.
3.3.4.5 Telemetry Reporting Rates
Table 11 states the minimum requirements for telemetry reporting rates for
DGs (Class 1, Class 2, Class 3, and Class 4) interconnecting to HONI‘s
distribution system.
Table 11: Telemetry Reporting Rates
Function Performance
Data measurements less than 10 s from change in field monitored quantity
Equipment status change less than 10 s from field status change
Data skew not applicable
Scan period for data measurements
Minimum 4 s (1)
Scan period for equipment status
Minimum 4 s (1)
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
96
3.3.5 Monitoring Reporting
HV Connected and Class 3 & 4 Facilities
Adverse situations involving the operation of the transmission or distribution
system, such as false trips or misoperations must be reported to the appropriate
Controlling Authority and regulatory authorities. It is expected that any protection
operation involving the customer facility will be fully documented along with
appropriate records from monitoring devices and provided to HONI immediately
following any such operation.
Any transmission or distribution connection facility owner must comply with
requests for sequence of events records (SER) or digital fault records as
requested by HONI or any controlling authority such as the IESO or NPCC within
30 days of request.
Waveforms and event data supplied to HONI must be in COMTRADE format.
Customer owned stations shall analyze all protection system misoperations in
order to take corrective actions to avoid future misoperations.
For further requirements, please refer to Section 8.
3.4 Performance Requirements
3.4.1 Power Quality
The DG facility must not negatively impact the power quality of Hydro One‘s
Distribution System. If the DG facility is found to cause problems and impact the
power quality of the system, they may be required to disconnect from HONI‘s
system until such a time when appropriate measures have been taken to mitigate
the adverse effects that the DG facility has been causing. IEEE Std. 519 should
be consulted to determine industry standards for power quality along with the
requirements in this document.
HONI requires Class 2, Class 3 and Class 4 DG installations (DG facilities greater
than 250 kVA) to be equipped with power quality meters that will monitor
continuously (and maintain logs) to ensure that power quality is maintained while
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
97
the DG is on-line and off-line, and in steady and dynamic states. This power
quality device is to be capable of high speed sampling to capture parameters such
as voltage, current and harmonics and measures shall be taken to ensure the
device is time synchronized. The DG Owner is required to install and commission
this at its own expense and shall allow HONI access to such PQ data as required.
This will allow HONI and the DG owner to assess the condition of the power output
of the DG facility.
3.4.1.1 Voltage Fluctuations (Flicker)
The DG facility must not create objectionable flicker for other customers on
Hydro One‘s system. The voltage dip at the PCC should not be more than
4% on connecting the single largest generation unit in the facility and
should remain within 10% of nominal voltage when the entire facility trips.
The DG Owner shall take steps to make sure that flicker requirements are
met – may need to add loss of synchronism protection, stagger generator
energization, etc.
Indicative values of planning levels for Pst and Plt in HONI‘s distribution
system are shown in the table below. These limits are from IEC 61000-3-7,
and the standard should be consulted for more details. These values
should be measured by an approved flicker-meter that conforms to
CAN/SCA-C610004-15.
Table 12: Pst and Plt Flicker Limits
44kV 27.6/25/13.8/12/8/4 kV
Pst 0.8 0.9
Plt 0.6 0.7
3.4.1.2 Voltage and Current Harmonics
The DG facility shall not inject harmonic current that causes unacceptable
voltage distortion on HONI‘s distribution system. The DG facility shall
follow the requirements of IEEE Std. 1547 and CSA 22.2 No. 107.1 for
maximum harmonic current distortion, also shown below in Table 12, and
ensure that the facility is operating within these limits. The DG Owner
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
98
and/or HONI may be required to implement measures that will mitigate the
harmonic distortions such as by adding harmonic filters, at the DG Owners
cost.
The CSA standard excludes harmonic currents that are due to harmonic
voltage distortions present on HONI‘s distribution system when the DG
facility is not connected. Inverters certified to this standard will be
considered to meet these requirements.
This document does not impose design limits to limit harmonic-caused
telephone interference problems as it is almost impossible to predict.
However, the DG Owner may want to make sure that the design complies
with all applicable standards and will not cause telephone interference.
Table 13: Current Harmonic Limits
Individual harmonic order, h
h < 11 11 ≤ h < 17 17 ≤ h < 23 23 ≤ h < 35 35 ≤ h THD
Distortion, percentage of current†‡
4.0 2.0 1.5 0.6 0.3 5.0
† The current is the greater of the distribution system maximum current integrated
demand (15 or 30 minutes) without the DG facility or the DG facility rated current capacity, transformed to the PCC when a transformer exists between the generators and the PCC.
‡ The maximum distortion presented in this table is for odd harmonics. Even harmonics are 25% of the odd harmonics presented above.
3.4.1.3 Voltage and Current Unbalance
The DG facility shall be capable of operating under existing conditions and
shall not cause deterioration of existing unbalance voltage and current
conditions.
3.4.1.4 Limitation of DC Injection
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
99
The DC current injection by the DG facility shall not be greater than 0.5% of
the full rated output current at the PCC after a period of six cycles following
the energization of Hydro One‘s distribution system.
3.4.2 Disturbances
The DG facility shall be designed, built and maintained to all applicable codes,
regulations and standards, along with the requirements of this document and shall
minimize the impact of:
Overvoltages during ground faults
Electric disturbances which can cause irregular power flows
Interference – radio, television and telephone
Audible noise
Other disturbances which may reduce the reliability of HONI‘s
distribution system
3.4.3 Generator
3.4.3.1 Reactive Power Requirements
The generator‘s system shall operate in the preferred range of 0.9 lag to
0.95 lead. Hydro One Connection Impact Assessments will assess the
impact of the generator over the specified range of power factors.
For certain Distribution System loading conditions, Hydro One may require
the generator to restrict reactive power within a specified range or to
operate at a specific power factor level to maintain Distribution System
voltage levels within the required ±6%.
Field settable fixed and dynamic power factor correction techniques may be
used if consultation with Hydro One reveals no adverse affect on the
distribution system.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
100
For generators that are IESO impactive, the reactive power compensation
at the generating units should be sufficient so as not to cause any material
increase in the reactive power requirements at the transmission system
transformer station due to operation of the units, at any distribution feeder
load conditions.
3.4.3.2 Speed Governors
Speed governors control the dynamic machine speed at all times and
controls machine active power when the generator is connected to the
distribution system.
Speed governors are required to control generator speed for
synchronization purposes as outlined in Section 3.1.19.
Speed governors are required to maintain acceptable power quality as per
Section 2.6.
Speed governors / generator active power also impacts Distribution System
voltage profiles that are affected by both active and reactive power flows
along the Distribution System feeders.
Speed governors are expected to limit generator active power to the name
plate capacity as submitted to Hydro One for the Connection Impact
Assessment. Hydro One Connection Impact Assessments will assess the
impact of the generator over that range of active power. For certain
Distribution System loading conditions, speed governors may be required
to limit active power to specific levels as required by Hydro One to maintain
Distribution System voltage levels within the required ±6%.
Speed governors may also be required to limit active power to specific
levels to ensure self-clearing anti-islanding protections remain effective for
certain Distribution System loading conditions (generator power output
must not exceed 50% of potential minimum islanded load if Transfer Trip is
not available).
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
101
Speed governor response also impact generator stability during power
system disturbances and their action needs to be considered in any system
stability studies that may be necessary for high impedance generator
connections.
Large generators (greater than 10 MVA) may have additional excitation
equipment requirements as specified by the IESO
At any time Hydro One may determine and require other specific speed
governor control or performance that is necessary to maintain acceptable
Distribution System conditions.
3.4.3.3 Excitation Equipment
Excitation equipment controls generator terminal voltage at all times and
controls generator reactive power when the generator is connected.
Excitation equipment is required to control generator terminal voltage and
PCC voltage for synchronization purposes as outlined in Section 3.1.19.
Excitation equipment is also required to maintain acceptable power quality
as per Section 2.6.
Excitation equipment / generator reactive power also impacts Distribution
System voltage profiles that are affected by both active and reactive power
flows along the Distribution System feeders.
Generally, the DG facility should not actively regulate the voltage at the
PCC (as per IEEE Standard 1547-2003), when the generator is connected.
Otherwise uncoordinated voltage control (such as hunting) could result and
cause excessive tap-changer and regulator operations and/or unnecessary
fluctuations in Distribution System voltage. If necessary, Hydro One may
specify some limited voltage regulation to maintain Distribution System
voltage levels within the required ±6% and/or acceptable Power Quality.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
102
Excitation equipment is expected to limit generator reactive power to the
name plate capacity as submitted to Hydro One for the Connection Impact
Assessment.
Excitation equipment is required to maintain power factor within a specific
range or limits as specified in Section 3.4.3.1.
For certain Distribution System loading conditions, Hydro One may require
the generator to restrict reactive power within a specified range or to
operate at a specific power factor level to maintain Distribution System
voltage levels within the required ±6%.
Excitation equipment can impact generator stability during power system
disturbances. Their action needs to be considered in any system stability
studies that may be necessary for high impedance generator connections.
Specific excitation equipment features and adjustments may be required to
help maintain generator stability during power system disturbances to avoid
loss of synchronism, particularly for synchronous generators.
Large generators (greater than 10 MVA) may have additional excitation
equipment requirements as specified by the IESO
At any time Hydro One may determine and require other specific excitation
equipment control or performance that is necessary to maintain acceptable
Distribution System conditions.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
103
4 Metering Requirements
Metering shall be in accordance with Hydro One Networks NOP 041 document ―Policy –
Distribution – Metering for Embedded Generators.‖ A copy of this document can be found in
Appendix H near the end of this document.
5 Connection Process Requirements
The Connection Process is outlined in the Ontario Energy Board Distribution System Code
Appendix F1 (reference 1). For a complete description of that process consult the OEB
website http://www.oeb.gov.on.ca/OEB/.
The following describes the final steps of the connection process (after completion of the
initial steps: initial contact, provision of information, generator develops plan, initial
consultation, application for impact assessment, Impact Assessment, Decision to Proceed
and Establish Scope of Project, Prepare Estimate and Present Offer to Connect).
5.1 Implementation
Implementations must proceed in accordance with the Ontario Energy Board Distribution
System Code Appendix F1 (reference 1). This involves the following:
Both parties commit to project and Generator commits to obtain required approvals. The
Generator:
prepares detailed engineering drawings;
submits all detailed plans to ESA for Plan Approval process (including
detailed single line diagram, interface protection); and
submits information to Hydro One for design review (including detailed single
line diagram, interface protection and metering details)
is recommended to provide this information to Hydro One within 30 days of
signing CCA so that design review can be done in a timely manner.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
104
Hydro One performs design review to ensure detailed engineering is acceptable. The
following is information is provided to the Generator:
the Interface protection design review;
Hydro One reviews detailed single line diagram and interface protection to
ensure acceptability; and
Recommend that this review be complete before equipment purchase.
Once Generator receives interface protection design review from Hydro One, then:
Generator tenders and awards contracts for equipment;
Builds - including ESA and other approvals;
Connection work; and
Line/equipment upgrades are completed.
Generator constructs facility and applies for ESA Electrical Inspection to receive
Authorization to Connect.
5.2 Connection Agreement
The Generator and Hydro One agree to, and sign, a Connection Agreement. Hydro One
and transmitter/host distribution system shall review existing agreements for required
revisions.
Note: A temporary connection agreement for the purpose of connection for
commissioning and verification may be signed at this point while negotiating final
Distribution Connection Agreement.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
105
6 Commissioning and Verification Requirements
Commissioning and Verification is required in accordance with the Ontario Energy Board
Distribution System Code Appendix F1 (reference 1). This involves the following:
Generator arranges for commissioning and testing of the generation facility;
Hydro One witnesses and verifies the commissioning process related to the
connection facilities; and
Transmitter/Host Hydro One witness and verify the commissioning process as
required
6.1 Hydro One Networks Inc. COVER Process
Hydro One requires the use of a ―Confirmation Of Verification Evidence Report‖
(COVER) to track the Generators Commissioning and Verification plans and execution.
The Customer Instructions for Completing the COVER form is contained on the form
itself (page 8). The complete 8-page COVER form is located in Appendix G. The
version of the COVER form may have changed since the time that this document has
been published.7 It has been provided for informational purposes only. The newest
version will be provided to the DG Owner at the appropriate stage of the project.
6.2 Hydro One Requirements for Commissioning and Verification
Hydro One's interest in the commissioning of the generator‘s equipment and systems is
limited to protection and control systems that impact operation of Hydro
One‘s distribution system. That involves the generator‘s protection and controls used for
the distribution system interface and synchronizing facilities for the distributed generation
connection. That includes end-end verification of all inputs and outputs (instrument
transformers, breaker positions, transfer trips, distributed generator end open schemes),
correct processing of those inputs by the protection and control systems for anti-
islanding and clearance of external faults, end-end verification of all outputs - breaker
tripping, breaker failure initiation, closing interlocks, alarms, and telemetry.
Hydro one requires commissioning of those protection and control systems to be
complete and thorough. Generator testing should conform to IEEE Standard 1547.1 -
7 The COVER form is subject to periodic review and revision. The current version will be provided by
Hydro One.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
106
Conformance Test Procedures for Equipment Interconnecting Distributed Resources
with Electric Power Systems. That standard specifies the type, production, and
commissioning tests that shall be performed to demonstrate that the interconnection
functions and equipment of the distributed resources (DR) conform to IEEE Std. 1547.
In general terms, the expected commissioning testing and supporting documentation
must include:
a) Instrument transformer checks (insulation, ratio/polarity, excitation and resistance
results).
b) Breaker timing trip tests for those breakers used to disconnect the distributed
generation from the Distribution System as a result of protection operations.
c) Verification of the transformer and neutral reactor impedances that impact the
generator ground integration with the Distribution System and correct connection,
where applicable.
d) Relay setting field work sheets (showing the measured results of the relay
calibration checks). Relay element settings/directioning are to be confirmed by AC
secondary injection.
e) Voltage measurements for any external power supplies used to supply the
protections should be recorded.
f) For AC and DC measurements, test equipment traceable to NRC standards should
be used.
g) Functional tests confirming the protection and control logic and timer settings.
h) Verification of test trips and alarm processing. Monitoring of breakers outputs
using suitable indicators can be used to avoid repeated tripping of the same from
different protections, but at least one live trip test per breaker (where the breaker
is proven to open) needs to be demonstrated.
i) Verification of control interlocks in protections
j) Verification of synchronizing system and synch-check controls.
k) Voltage phasing checks (prior to first connection).
l) Secondary load readings, voltage and current phasor checks (immediately after
first connection) to prove correct magnitude and phase angle of all secondary AC
voltage and current circuits correspond to primary quantities. Primary current,
voltage, MW and MVAr values must be calculated from the measured secondary
values and compared to known primary quantities at adjacent locations.
m) The completed documentations must clearly indicate the station, protection
designation, settings date, test date, the name of the tester(s), relay type
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
107
(manufacturer and model), test equipment details (manufacturer, model, serial
number, accuracy, last calibration date), instrument transformer ratios. There
should be a cross-reference to the submitted design documentation (drawing
numbers and revision).
n) Verification of Transfer Trips and DGEO end-end checks. This will require
participation and coordination with Hydro One.
o) The Distributed Generator shall make modifications to correct any problems that
are found during commissioning.
p) As-constructed drawings (single line diagram showing protection and metering, AC
and DC schematics, final relay settings, testing and commissioning results for
interface protection etc.) shall be submitted to the Distributor for its records within
sixty (60) business days after the connection, as stipulated in the Connection
Agreement.
As per the COVER, Summary of testing results and certificates must be kept on file for a
minimum period of 7 years by the Customer (as indicated by IESO Market Rules, Chp.4,
5.1.3). Hydro One Networks Inc. may require this information, on an exception basis.
Complete documentation of all commissioning results will be required for the interface
protections and synchronizing controls, signed and stamped by a Professional Engineer
registered in the Province of Ontario. Those results must provide complete assurance
that the distributed generator equipment has been proven to function correctly, as per
the accepted design submissions and the Distribution Connection Agreement.
7 Maintenance Requirements
7.1 Protection and Control Systems Equipments
7.1.1 The Generator shall re-verify its station protections and control systems that impact
the Hydro One Distribution System. That would include the systems that were
confirmed and verified as part of the COVER process. Maintenance requirements
will be equivalent to what Hydro One would require for re-verification of its own
facilities that have similar potential impact to the Distribution System, normally every
eight (8) years.
7.1.2 Within three (3) months of Connection, the Generator shall provide Hydro One with
their proposed protection and control reverification program (including test
procedures and schedules).
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
108
7.1.3 Within thirty (30) working days of receiving the above documentation or as required
by the Code, Hydro One shall notify the Generator that it:
(a) agrees with the proposed reverification program and test procedures; or
(b) requires changes in the interest of safety or maintaining the reliability of the
Distribution System. Such request for changes shall be sent to the Generator
Promptly.
7.1.4 For those tests that require Hydro One‘s participation or witnessing, the Generator
shall provide Hydro One with no less than fifteen (15) working days notice.
Note: All tests must be coordinated and approved ahead of time through the normal
outage and work management system planning processes.
7.1.5 The Generator will complete the re-verification in accordance with 7.1.3 above and
submit complete documentation of the test results to Hydro One within one month of
the completed tests.
8 Reporting Requirements for DGs
The Customer shall keep a written or electronic log. This log will record the date and time,
along with a description of the incident. The incidents recorded, must include, but are not
limited to those in the table below. The Generator must make the log, or a copy of the log,
available for the Distributor‘s review upon request, within five (5) working days of that
request.
The Customer will provide reports to the Distributor, Distribution Eng/Officer (See Schedule
F, Contact List - section 1) either on a requested basis, or for specific types on incidents that
require reports as per the table within five (5) working days of the incident.
The report must include, but is not limited to:
Distributed Generation Facility and/or Generator Name and Account Number
Supply Feeder
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
109
Date and time of incident
General description of the incident, including cause, if known
Did the Generator's equipment trip correctly?
Voltage (if available)
Frequency (if available)
Amps
Active Power (kW or MW)
Reactive Power (kVAr or MVAr)
Any available oscillography or digital fault records (DFR) related to the above
Generator connection status (individual units)
Transfer Trip signal status
Distributed Generator End Open signal status
Which relays operated (targets & description)? Any available sequence of events
records (SER) related to the above
Corrective actions taken
These are the incident types to be recorded:
Note: the Distributor may modify the incidents to be logged or recorded in the table below,
based on those relevant to the Distribution System specific to this Connection.
Table 14: Incident Logging
Incident Logged Report Required Real Time
Communication
Protection System Malfunction or Failure at the Facility (see D.3.9.6)
Yes As requested Day of
Trip from the Facility‘s Relay Operation
Yes As requested Within Hour
Electrical failure / incident at the Facility
Yes As requested As requested
Mechanical failure / incident at the Facility
Yes As requested As requested
Trip from Feeder incident Yes As requested Within Hour
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
110
9 References
1. Ontario Energy Board Distribution System Code Appendix F - Process and Technical
Requirements for Connecting Embedded Generation Facilities - Section F.2 Technical Requirements
2. Ontario Energy Board Distribution System Code
3. IEEE Std 1547-2003 - IEEE Standard for Interconnecting Distributed Resources with
Electric Power Systems
4. IEEE Std 1547.1-2005 - IEEE Standard Conformance Test Procedures for Equipment
Interconnecting Distributed Resources with Electric Power Systems
5. IEEE P1547.2/D11 Draft Application Guide for IEEE Standard 1547, Interconnecting Distributed
6. IEEE Std 1547.3-2007 - IEEE Guide for Monitoring, Information Exchange, and Control of
Distributed Resources Interconnected with Electric Power Systems
7. IEEE Std 519-1992 - IEEE recommended practices and requirements for harmonic control in electrical power systems
8. IEEE Std 929-1988 - IEEE recommended practice for utility interface of residential and
intermediate photovoltaic (PV) systems
9. IEEE Std C37.90-2005 - IEEE Standard for Relays and Relay Systems Associated with
Electric Power Apparatus
10. IEEE Std C37.90.1-2002 - IEEE Standard for Surge Withstand Capability (SWC) Tests for Relays and Relay Systems Associated with Electric Power Apparatus
11. IEEE Std C37.90.2-2004 - IEEE Standard for Withstand Capability of Relay Systems to
Radiated Electromagnetic Interference from Transceivers
12. IEEE Std C37.90.3-2001 - IEEE standard electrostatic discharge tests for protective relays
13. IEEE Std C57.13-2008 - IEEE Standard Requirements for Instrument Transformers
14. IEEE Std C57.13.1-2006 - IEEE Guide for Field Testing of Relaying Current Transformers
15. IEEE Std C57.13.2-2005 - IEEE Standard Conformance Test Procedures for Instrument Transformers
16. IEEE Std 929-1988 - IEEE recommended practice for utility interface of residential and
intermediate photovoltaic (PV) systems
17. IEEE Std 1159-1995 - IEEE Recommended Practice for Monitoring Electric Power Quality.
18. IEEE Std 242-2001 - IEEE Recommended Practice for Protection and Coordination of
Industrial and Commercial Power Systems - IEEE Buff Book
19. IEEE Std 1109-1990 - Guide for the Interconnection of User-Owned Substations of Electric Utilities
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
111
20. IEEE Std 1001-1988 - IEEE Guide For Interfacing Dispersed Storage and Generation
Facilities with Electric Utility Systems
21. IEEE Std 1453-2004 - IEEE Recommended Practice for Measurement and Limits of
Voltage Flicker on AC Power Systems
22. IEEE Std 493-2007 - Gold Book - IEEE Recommended Practice for the Design of Reliable Industrial and Commercial Power Systems
23. IEEE Std 1100-2005 - EMERALD BOOK - IEEE Recommended Practice for Powering and
Grounding Electronic Equipment
24. IEEE Std 1250-1995 - IEEE Guide for Service to Equipment Sensitive to Momentary
Voltage Disturbances
25. IEEE Std 100-1997 - IEEE Standard Dictionary of Electrical and Electronics Terms
26. IEEE Std 315-1975 - Graphic Symbols for Electrical and Electronics Diagrams
27. IEEE Std C37.2-2008 - IEEE Standard Electrical Power System Device Function
Numbers, Acronyms, and Contact Designations
28. IEEE Std C37.1-2007 - IEEE Standard for SCADA & Automation Systems
29. IEEE Std 80-2000 - Safety in AC Substation Grounding
30. IEEE Std 81-1983 - Guide for Measuring Earth Resistivity, Ground Impedance, and Earth
Surface Potentials of a Ground System Part 1: Normal Measurements
31. IEEE Std C62.23-1995 - IEEE Application Guide for Surge Protection of Electric Generating Plants
32. IEEE Std C37.29-1981 - IEEE Standard for Low-Voltage AC Power Circuit Protectors
Used in Enclosures
33. IEEE Std C57.12 - IEEE Standard General Requirements for Liquid Immersed Distribution,
Power and Regulating Transformers
34. IEEE Std C57.12.13 - Conformance Requirements for Liquid Filled Transformers Used in Unit Installations including Unit Substations
35. IEEE Std C57.13 - IEEE Standard Requirements for Instrument Transformers
36. IEEE Std C37.20.1-2002 - IEEE Standard for Metal-Enclosed Low-Voltage Power Circuit
Breaker Switchgear
37. IEEE Std C37.20.2-1999 - IEEE Standard for Metal-Clad Switchgear
38. IEEE Std C37.20.3-2001 - IEEE Standard for Metal-Enclosed Interrupter Switchgear
39. IEEE Std C37.30-1997 - IEEE Standard Requirements for High Voltage Switches
40. IEEE Std C62.41-1991 - IEEE Recommended Practice for Surge Voltages in Low-Voltage
AC Power Circuits
41. IEEE Std C37.010-1999 - IEEE Application Guide for AC High-Voltage Circuit Breakers Rated on a Symmetrical Current Basis
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
112
42. CSA Std C22.1-2009 - Canadian Electrical Code, Part I Safety Standard for Electrical
Installations - Twenty-first edition
43. CSA Std C22.2 - Canadian Electric Code Part II
44. CSA Std C22.3 - Canadian Electric Code Part III (Electricity Distribution and Transmission
Systems).
45. CSA Std C22.3 No. 9-2008 - Interconnection of Distributed Resources and Electricity
Supply Systems
46. CSA Std C235-83-CAN3 - Preferred Voltage Levels for AC Systems, 0 to 50,000 V Electric Power Transmission and Distribution
47. CSA Std C22.2 No. 107.1-95 - Commercial and Industrial Power Supplies
48. CSA Std C22.2 No. 31-M89 (R2000) - Switchgear Assemblies
49. CSA Std C22.2 No. 193-83 (R2000) - High-Voltage Full-Load Interrupter Switches
50. CSA Std CAN3-C308-M85 - Principles and Practices of Insulation Coordination
51. UL 1741 - Inverters, Converters, and Controllers for Use in Independent Power Systems
52. IEC TR3 61000-3-7 - Principles and Practices of Insulation Coordination Assessment of Emission Limits for Fluctuating Loads in MV and HV Power Systems
53. IEC 61000-4-15 - Flickermeter—Functional and Design Specifications
54. IEC 61400-21 - Wind Turbine Generator Systems—Part 21: Measurement and Assessment
of Power Quality Characteristics of Grid Connected Wind Turbines—Ed. 1.0 (2001-12).
55. NEMA CC-1 – Electric Power Connectors for Substations
56. NEMA LA-1 – Surge Arresters
57. NEMA MG-1 – Motors
58. W. Xu, K. Mauch, and S. Martel. ―An Assessment of the Islanding Detection Methods and Distributed Generation Islanding Issues for Canada, A report for CANMET Energy Technology Centre‖ -Varennes, Nature Resources Canada, 65 pages.
59. Wilsun Xu, Guibin Zhang, Chun Li, Wencong Wang, Guangzhu Wang, Jacek Kliber, "A power line signaling based technique for anti-islanding protection of distributed generators: part I: scheme and analysis", IEEE Trans. Power Delivery, v22, n3, July 2007, pp. 1758 –
1766
60. Wencong Wang, Jacek Kliber, Guibin Zhang, Wilsun Xu, Blair Howell and Tony Palladino, ―A Power Line Signaling Based Scheme for Anti-islanding Protection of Distributed Generators: Part II: Field Test Results‖, IEEE Trans. Power Delivery , v22, n3, July 2007, pp. 1767 – 1772.
61. W. Freitas, Z. Huang, W. Xu, ―A practical method for assessing the effectiveness of vector surge relays for distributed generation applications‖, IEEE Trans. Power Delivery, v20, n1, pp. 57-63, Jan. 2005.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
113
A Appendix A - Device Number Description
The following is a list of relevant device numbers and their meaning:
21 - Distance Relay
25 - Synchronizing or Synchronism-Check Device
27 - Undervoltage Relay
31 - Separate Excitation Device
32 - Directional Power Relay
37 - Undercurrent or Underpower Relay
42 - Running Circuit Breaker
46 - Reverse-phase or Phase-Balance Relay
47 - Phase-Sequence Voltage Relay
49 - Machine or Transformer Thermal Relay
50 - Instantaneous Overcurrent
51 - AC Time Overcurrent Relay
52 - AC Circuit Breaker
53 - Exciter or DC Generator Relay
55 - Power Factor Relay
57 - Short-Circuiting or Grounding Device
59 - Overvoltage Relay
60 - Voltage or Current Balance Relay
61 - Machine Split Phase Current Balance
64 - Ground Detector Relay
67 - AC Directional Overcurrent Relay
68 - Blocking Relay
79 - AC-Reclosing Relay
81 - Frequency Relay
86 - Lockout Relay
87 - Differential Protective Relay
88 - Auxiliary Motor or Motor Generator
89 - Line Switch
90 - Regulating Device
91 - Voltage Directional Relay
92 - Voltage and Power Directional Relay
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
114
B Appendix B – Neutral Reactor and Grounding Transformer Impedance Calculations for Inverter Based DG Facilities
The following is two examples for calculating the impedance of grounding transformers for
Inverter based DG facilities:
Example 1: for 10 MVA DG Facility connected at 27.6 kV,
Base impedance = 27.6kV2/10MVA = 76.2Ω,
Then X0 = 0.6 x 76.2Ω ± 10% = 45.7Ω ± 10%
Example 2: for 2 MVA generation connected at 27.6 kV,
Base impedance = 27.6kV2/2MVA = 381 Ω,
Then X0 = 0.6 x 381Ω ± 10% = 228.6Ω ± 10%
The following is two examples for calculating the impedance of neutral reactors for Inverter
based DG facilities:
Example 1: for 10 MVA DG Facility, with ten 1 MVA DGITs connected
at 27.6 kV,
Base impedance = 27.6kV2/1MVA = 762Ω,
Then X0 = 0.6 x 762Ω ± 10% = 457.2Ω ± 10%
Example 2: for 2 MVA generation connected at 27.6 kV,
Base impedance = 27.6kV2/2MVA = 381 Ω,
Then X0 = 0.6 x 381Ω ± 10% = 228.6Ω ± 10%
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
115
C Appendix C – Timing Diagrams
The following are a few sample timing diagrams for informational purposes. These have been created to represent a
realistic sequence of events and the associated timings for different applications. These times may change due to site
specific requirements and thus, timing requirements shall be confirmed with HONI for specific DG projects.
Figure 17 and 18 represent timing for fault and island detection for DGs not equipped with Transfer Trip from HONI,
coordinating with HONI reclosers with a reclose time of 500ms and 1s respectively.
Figure 17: No Transfer Trip with 500ms Reclosure Upstream
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
116
Figure 18: No Transfer Trip with 1s Reclosure Upstream
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
117
Figure 19 and 20, shown below, show timing requirements DGs equipped with Transfer Trip from HONI, coordinating with
HONI reclosers with a reclose time of 500ms and 1s respectively.
Figure 19: Transfer Trip with 500ms Reclosure Upstream
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
118
Figure 20: Transfer Trip with 1s Reclosure Upstream
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
119
D Appendix D – Anti-Islanding Protection
The following is background information on Anti-Islanding Protection, its purpose, and some
rational behind some requirements. Transfer Trip and Distributed Generator End Open is
discussed. Also, a typical distribution system is shown and possible island formations are
discussed. This information is provided as informational only. Requirements are listed in
Section 3 of this document.
Transfer Trip, Distributed Generator End Open and Inrush Blocking (LSBS)
Transfer Trip (TT), Distributed Generator End Open (DGEO) and Inrush Blocking (Low Set
Block Signal – LSBS) are often required to mitigate the adverse impacts of DG connection and
islanding, as detailed below.
Transfer Trip (TT) is a protection trip signal that is sent from the Hydro One supply
source breaker or recloser to the DG when the DG is required to be disconnected.
Distributed Generator End Open (DGEO) is a real time signal that is continuously sent
from the DG to the Hydro One supply source breaker or recloser. It establishes the
connection status of the generation equipment. For 3-wire connections, the DGEO signal
is derived from all breakers/circuit switchers at the interface between the DG generation
and the PCC necessary to establish DG generation connectivity. For 4-wire
connections, the DGEO signal is derived from the DG HVI switch only. Refer to
Appendix E for more information regarding the DGEO signal.
Low Set Block Signal (LSBS) is a signal that is sent from the DG to the Hydro One
supply source breaker or recloser, whenever a large DG interface transformer (DGIT) is
being energized. Detection of this signal transition at the Hydro One supply source
breaker or recloser location will cause the most sensitive low-set (fuse-saving) protection
to be temporarily blocked. This will prevent tripping of the Hydro One supply source
during the period when there is large energizing inrush current due to the DGIT. Refer
to Appendix E for more information regarding the LSBS signal.
Because the momentary LSBS signal will always be sent just prior to reconnection, (near
the end of the DGEO open condition), it is possible to combine both DGEO and the
LSBS functions as one signal through a communication channel from the DG facility to
the Hydro One source energizing location(s).
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
120
DG Islanding
DG islanding can expose Hydro One Transmission and Distribution Systems and customers to
unstable voltage and frequency and other adverse impacts. A DG island is formed if a DG
remains connected to a portion of the Distribution System after that portion is separated from
the normal Hydro One supply. Most typically, DG islanding can occur when the feeder breaker
or other isolating device at a TS or DS or along a radial-connected feeder is opened.
Some of the causes that may lead to DG islanding are as follows:
A fault that is detected and cleared by the utility before it can be detected and cleared by
the DG. Most DG islands will be established this way.
Emergency switching of distribution system and loads.
Equipment malfunction.
Operating or human error.
Foreign interference or other acts of nature.
Adverse Impacts of DG Islanding
Potential adverse impacts of DG islands include:
a) Abnormal voltage and frequency excursions outside of the acceptable ranges because
of DG voltage regulation limitations.
b) Excessive temporary overvoltage (TOV) can occur if DG sources that are not effectively
grounded back-feed single-line-ground faults.
c) Extreme overvoltage from ferroresonance between the nonlinear magnetizing
inductance of DGIT/induction generators and connected capacitance and system
capacitance.
d) Unpredictable DG energy sources that are not controlled by the utility. This includes
generation sources and abnormal phase voltages caused by back-feed through multi-
core 3-phase DG interface transformers in the presence of single-phase switching or
other open circuit supply conditions.
e) Failure to clear certain faults that cannot be detected by DG self-clearing protections
within required time.
f) Interference with the restoration of normal supply from the utility.
g) Asynchronous paralleling if DG is present when Hydro One supply is restored.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
121
The risks of these adverse impacts include:
a) Inadequate power quality - voltage and frequency.
b) Damage - to customer and utility line equipment as a result of overvoltages or sustained
or prolonged electrical faults where protections are insensitive or slow clearing.
c) Prolonged customer outages resulting from failed automatic reclosure or delays in
establishing safe conditions for isolation and repair of damaged equipment.
d) Safety hazards to public and utility workers since lines may be energized when it is
assumed to be disconnected from all energy sources.
e) Increased liability and costs associated with all of the above.
These impacts must be avoided by maintaining adequate controls over the design and
operation of the DG interconnections. Transfer Trip (TT) and Distributed Generator End Open
(DGEO) schemes are important tools that are required to avoid these adverse effects for certain
configurations.
Hydro One Supply Stabilizes Voltage and Frequency
Hydro One is responsible for supply and voltage regulation of Hydro One Distribution Systems
and maintains Distribution System voltages at acceptable levels as required by the OEB.
Frequency is maintained very close to 60 Hz by the synchronized interconnection of the Hydro
One Transmission System to the Eastern Interconnection of the North American Electric
Reliability Corporation (NERC).
Voltage and frequency will be maintained under normal system conditions as long as normal
Hydro One supply remains connected to the Distribution System.
Expected Frequency and Voltage Deviations in DG Islands
When a DG island occurs, island voltages and frequency will depend entirely on the interaction
between the islanded generation and load. Maintaining an island within acceptable limits would
require at least one DG in the island to actively regulate frequency and voltage to match
changing island load demands. Furthermore the DG capacity would have to be large enough to
sustain the extreme range of load demands that may exist in the island. DGs cannot meet
these conditions for the following reasons:
HONI does not permit DG voltage regulation systems to actively regulate voltage. This
avoids mal-coordination of Distribution System voltage regulation and excessive
operation of Hydro tap-changers and voltage regulators.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
122
Variable production conditions prevent DG capacity from being capable of meeting the
exact demands of any specific local loads or power transfers. As a result, DG island
frequency and voltage can be expected to drift outside of the acceptable limits because
of these inherent DG control and capacity limitations.
The direction (over or under) of frequency and voltage change for a DG island will
depend upon the relative mismatch of net real and reactive power between the islanded
DG and load. If the active power generation is less than the active power consumed by
the load, the island frequency will drop. If the active power generation exceeds the
active power consumed by the load, the island frequency will rise.
Change in island voltage magnitude depends similarly on mismatch between distributed
generation reactive power output and the reactive power demands of the islanded load.
The rate-of-change of frequency and voltage for a DG island will depend upon many
factors. These factors include the amount of power unbalance, network impedances,
voltage dependency of the feeder loads and dynamic characteristics of the islanded
generation and loads (inertias of the interconnected machines and transient reactances).
Even short duration DG islands may be too long to prevent adverse DG islanding
impacts, unless specific design precautions are implemented.
Possibility of Extreme Overvoltages and Back-feeds through Customer
Transformers
Ferroresonance and single-line-ground faults can cause extreme or excessive over-
voltages for some DG island configurations. These over-voltages are capable of causing
damage to customer and Hydro One equipment.
Back-feeds through multi-core 3-phase DG interface transformers in the presence of
single-phase switching or other open circuit supply conditions. These voltages pose a
safety hazard to public and utility workers for fallen conductors or when circuits are
assumed to be dead but in fact are energized.
These over-voltage and back-feed effects are largely dependent upon the size,
grounding and magnetic-core characteristics of the DG interface transformer (DGIT)
connections. There are many ways to avoid or minimize these effects. That includes
the following:
i. The use of Transfer Trip
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
123
ii. Use of a DG HVI to be tripped whenever an unbalanced condition is detected
at the DG location
iii. Effective-grounding of DGIT
iv. Avoiding the use of multi-core transformers for 3-phase connections in the
presence of single phase switching upstream, by using three individual
single-phase (single-core) DGIT connections
v. Avoiding single-phase switching of 3-phase transformers (where possible) or
minimizing circuit capacitance from the DGIT to these locations.
Automatic Reclosure
Transient faults on over-head line conductors caused by lightning, wind, tree branches
falling, or other momentary foreign contact constitute approximately 85-90% of all faults.
Hydro One uses the standard utility practice of automatic reclosure on distribution
feeders with over-head line-sections to minimize supply interruptions for transient faults.
Automatic reclosure is not generally used for feeders with extensive underground cable
sections because cable faults are exposed to far fewer naturally occurring transient fault
conditions. Also faults on cables are much more likely to be permanent requiring repairs.
Benefits of Automatic Reclosure
Automatic reclosure has the following advantages:
Minimizes supply interruption to customers by automatically restoring the feeder to
service as quickly as possible following transient faults.
Minimizes damage at the fault and stress on equipment supplying the fault.
Reduces operating costs. Less time and materials required to repair damage and restore
service.
Prevents blowing of fuses at tapped Distribution stations and lateral feeds resulting in all
of the above.
How Automatic Reclosure Works
For the first occurrence of the fault on any portion of the faulted feeder, high-speed
sensitive ―low set‖ protection operates quickly to de-energize the feeder.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
124
Following the first protection operation, the Hydro One feeder breaker or reclosers are
automatically reclosed to restore supply to load customers as quickly as possible.
Typical reclosing times are 0.5 to 1 second for feeder breakers and 1.5 to 2 seconds for
reclosers.
Reclosing time must allow for the fault to extinguish and de-ionize.
Reclosing time must also allow some time for the inertia and back emf of large motors to
decay (to about 40% of normal voltage) and be disconnected by automatic controls.
Automatic Reclosure Requires DG to Disconnect Quickly
Automatic reclosure can succeed only if the fault arc is extinguished and de-ionized. Otherwise
the fault is likely to re-strike after the feeder is re-energized.
If the DG has not disconnected at the time that automatic reclosure takes place, the
reclosure would asynchronously re-parallel to all DGs and any rotating motors that
remained connected in the island.
Extreme mechanical stresses associated with asynchronous paralleling could damage
DG generators, customer motors, switching equipment and any transformers that are
connected in series between these energy sources.
The potential impact of asynchronous connection of inverter-fed DGs is less certain and
will depend on their individual design. However, if island voltage can be sustained
causing other generators and motors to remain connected, then asynchronous reclosure
must still be avoided.
For the above reasons, all DGs must be quickly disconnected whenever a feeder fault is
detected – before reclosure takes place.
Limitations of DG Self-Clearing Protection Response Times
Based on fault in-feed, DGs cannot distinguish between faults on either side of the utility
feeder breaker or recloser that supplies them. To avoid nuisance trips, some time delay
is required by the DG protection to allow coordination with the faster utility protections to
clear those out-of-zone faults. If that delay is too long, automatic reclosure will be
impaired.
DG anti-islanding protection cannot prevent DG islanding. It can only detect an island
after islanding occurs.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
125
All passive DG anti-islanding detection methods rely on an unbalance or mismatch
between distributed generation power output and power demands of the connected load
on the isolated island. DG island frequency and voltage can be expected to drift (as per
section ―Expected Frequency and voltage deviations in DG islands‖ above).
Close matching of both active and reactive power would be an extremely unlikely
condition for a prolonged period. Sooner or later, mismatches will cause the voltage or
frequency to drift outside the limits specified in Sections 3.2.13 and 3.2.14.
If by chance the active and reactive power produced by islanded DG happens to be
close to the islanded load demand, then the island may survive for a longer period
before DG self-clearing protections will detect and disconnect the generation.
In some cases, DG self-clearing anti-islanding protections cannot be relied on to
guarantee that the DG will disconnect itself before automatic reclosure takes place. In
those cases, TT and DGEO schemes are required. Refer to appropriate sections for
requirement conditions.
Maximum Detection Times Available for DG Self-Clearing Protections
There are limited time windows available following the formation of an island during which time
DG self-clearing protections have to disconnect the generator before reclosure takes place.
If there is a fault on the feeder at the time the DG island is formed, the DG fault
protection must detect the fault and initiate clearance.
If there is no fault on the feeder at the time the DG island is formed, the DG anti-
islanding protection must detect the island condition and disconnect the generation from
the Distribution System.
Timing diagrams for self-clearing DG protections are shown in Appendix C in Figure 17 and
Figure 18 for a 0.5-second reclosure and for a 1.0 second reclosure, respectively. The times
are based on the following assumptions and constraints:
The assumed maximum fault detection time for Hydro One instantaneous low set
protections is 33ms. More commonly fault detection time will be 16 ms or less.
The reclosure timer is initiated without delay, immediately after the fault is detected by
the Hydro One feeder protection.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
126
The assumed maximum Hydro One fault clearance time is 83 ms after the fault is
detected (5-cycle breaker opening time for oil dead-tank breakers).8
200 ms fault extinction and de-ionization time and/or drop out of motor controls is
required after the last source trips, prior to reclosure.
The DG generator breaker is a 3-cycle breaker.
To prevent interference with automatic reclosure (1 second reclosure):
Self-clearing DG anti-islanding protections must be capable of island detection within
617ms to coordinate with a 1 second reclosure time.
DG fault protection must be capable of detecting all 3-phase and phase-ground faults to
the extreme ends of the supply feeder within 783ms.
For reclosure times longer than 1 second, the protection response times can be
lengthened by equivalent amounts.
TT will be required to speed up DG clearance if the above conditions cannot be met.
To prevent interference with automatic reclosure with a reclose time of 500ms:
Self-clearing DG anti-islanding protections would have to be capable of detecting an
island condition within 117ms.
DG fault protections must be capable of detecting all 3-phase and phase-ground faults to
the extreme ends of the supply feeder within 283ms.
It is expected that DG self-clearing protections cannot selectively and reliably detect fault
and island conditions in such a short time. TT and DGEO will always be required to
speed up DG clearance where 0.5-second reclosure times are used.
Transient Response of DG Islands
Hydro One transient stability studies for some typical synchronous generators have
demonstrated some consistent effects that various generation-to-feeder load ratios have
on DG voltage and speed (frequency).
8 Hydro One clearance time (after fault detection) may be only 50 ms if fast auxiliary relays and 3-cycle
breakers are used.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
127
These studies have shown that for 50% generator rating to feeder load ratios, generator
frequency declined steadily to about 53 Hz within 1 second. Voltage declined rapidly to
about 75% within about 100 ms and recovered somewhat to about 93% within 1 second.
Such frequency excursion to 53 Hz should ensure that the under-frequency protections,
set as specified in Section 3.2.13 will clear in much less than 1 second (160 ms for
frequency < 59.3 Hz).
Such voltage excursion to 75% may take up to 2 seconds to clear for protection set as
per Section 3.2.14 (50 ≤ V < 88%).
For higher generator rating to feeder load ratios, frequency and voltage does not drift
outside the limits specified in Sections 3.2.13 and 3.2.14.
Generic models for other types of generators - self-fed induction (SFIG), Double-fed
Asynchronous (DFAG), inverters and static power converters are not sufficiently
available to guarantee that DG anti-islanding protections will operate in sufficient time for
all conditions to prevent interference with automatic reclosure.
Based on the above, Hydro One has established a 50% active power unbalance
threshold (DG aggregate capacity / minimum load) above which TT is required to be
used to avoid interference with Distribution System automatic reclosure schemes.
This only applies where automatic reclosure time is 1-second or longer.
Requirements for Transfer Trip
Transfer Trip (TT) is a protection trip signal that is sent from the Hydro One supply source
breaker or recloser to the DG when the DG is required to be disconnected. TT is required to
prevent the adverse effects of DG islands whenever other means cannot reliably do so or are
more expensive. TT is required to quickly disconnect the DG from the Distribution System for
the conditions listed in Section 3.2.16.
TT timing requirements
Refer to Appendix C, Figure 19, and Figure 20 for TT timing requirements.
DGEO Requirements
Distributed Generator End Open (DGEO) is a real time signal that is continuously sent
from the DG to the Hydro One supply source breaker or recloser.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
128
For ungrounded 3-wire connections, where the DG source cannot contribute ground fault
current, the DGEO signal is derived from all breakers/circuit switchers at the interface
between the DG generation and the PCC necessary to establish DG generation
connectivity. It establishes the connection status of the generation equipment and is
used to block automatic reclosure should DG fail to disconnect after the Hydro One
supply is disconnected. For 3-wire connections that do not have an HVI, connectivity of
the generators will be established by LVI connection logic that mimics all of the possible
generation connection paths.
For 4-wire connections, the DGEO signal must be derived from the DG HVI switch only.
For 4-wire connections all DG ground sources must be connected to the DG side of the
HVI switch and must be disconnected before Hydro One source can be permitted to
energize the feeder. That is because any fault that occurs immediately following Hydro
One energization of the feeder is almost certain to be permanent, and Hydro One low-
set fuse-saving protections are blocked. This allows coordinated clearance of the down-
stream reclosers and fuses with the Hydro One source timed protections.
DGEO requirements are specified in Section 3.2.17.
Low Set Block Signal Requirements
The Low Set Block Signal (LSBS) is a signal that must be sent from the DG to the Hydro One
supply source breaker or recloser, whenever a DG interface transformers (DGIT) is being
energized. This will prevent tripping of the Hydro One supply source during the period when
there is large energizing inrush current to the DGIT. Detection of this signal transition at the
Hydro One supply source breaker or recloser location will cause the most sensitive low-set
(fuse-saving) protection to be temporarily blocked for a short duration, sufficient to allow the
DGIT inrush current to subside.
The LSBS signal can be combined with the DGEO signal through a shared communication
channel from the DG facility to Hydro One.
LSBS requirements are specified in Section 3.2.22.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
129
Application of TT and DGEO “50% rule” Requirements to DG Islands
The 50% TT rule is intended to preserve the benefits of automatic reclosure following transient
line fault conditions, by ensuring DGs do not interfere with the successful operation of automatic
reclosure schemes. Automatic reclosure is not initiated for other types of permanent faults –
recurring line faults, transformer faults, bus faults or breaker failure condition. In these cases,
providing other adverse impacts are minimal for short-duration DG islanding, self-clearing anti-
islanding protections (over/under voltage and over/under frequency) may be sufficient to
disconnect the generation from the island when frequency and voltage transcend the limits
specified in Sections 3.2.13 and 3.2.14. In all cases, high reliability is required for all protection
schemes that are required to maintain the integrity of the Distribution System.
Typical DG islands that can be formed during transient fault conditions are illustrated in Figure
21 and the following discussion below.
Figure 21: Typical Distribution System with DG Interconnections
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
130
Local Area DG Islands
Local Distribution System DG Islands are formed whenever feeder reclosers or TS breakers are
tripped from feeder or line protections interrupting the supply to a portion of the Distribution
System. For each potential local DG island scenario, the aggregate capacity of the islanded DG
must be assessed in relation to the minimum connected islanded load. If the islanded DG
aggregate capacity is greater than 50% of the minimum load of the connected island, then TT
will be required to be sent from the most strategic Hydro One supply location(s) to disconnect
the DG to ensure successful reclosure operations. The TT may be sent directly from the Hydro
One switching device location to the DG or a cascading arrangement may be used to redirect
the TT to the DG via another marshalling location (usually the TS).
Recloser DG Island
A recloser DG island forms when a feeder recloser operates for a feeder fault,
interrupting the Hydro One supply to a section of a feeder to which DG is connected.
In the example, Figure 21, DG2, DG4 and DG5 will be islanded by the adjacent Hydro
One source-side reclosers opening.
Typical automatic reclose times are 1.5 to 2 seconds for reclosers.
To prevent interference with automatic reclosure self-clearing DG anti-islanding
protections must be capable of detecting an island condition within about 1.1 second for
a 1.5 second reclose time and 1.6 second for a 2-second reclose time.
This will be assured if the aggregate capacity of the islanded DG is less than 50% of the
minimum load on the load-side of a feeder recloser. Otherwise, TT will be required to be
sent to disconnect the DG whenever the feeder recloser is opened.
Feeder-breaker DG Island
A feeder-breaker DG island forms when feeder protection operates for a feeder fault,
opening a TS feeder-breaker and interrupting the Hydro One supply to the whole feeder
to which DG is connected.
In the example, Figure 21, DG1 – DG4 will be islanded by the opening of the M2 feeder
breaker.
Typical automatic reclose times are 0.5 to 1 seconds for feeder breakers.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
131
To prevent interference with a 1.0 second automatic reclose time, self-clearing DG anti-
islanding protections must be capable of detecting an island condition within about 0.6
second. This will be assured if the aggregate capacity of the islanded DG exceeds 50%
of the minimum load on the load-side of a feeder recloser. Otherwise, TT will be
required to be sent to disconnect the DG whenever the TS breaker is open.
To prevent interference with a.0.5 second automatic reclose time, self-clearing DG anti-
islanding protections would have to be capable of detecting an island condition within
117ms. It is expected that DG self-clearing protections cannot selectively and reliably
detect fault and island conditions in such a short time. TT and DGEO will always be
required to speed up DG clearance where 0.5-second reclosure times are used.
If the aggregate capacity of the islanded DG exceeds 50% of the minimum load on the
load-side of the TS breaker, TT will be required to disconnect the DG whenever the TS
breaker is opened.
LV Bus DG island
An LV bus DG island forms when a main terminal line protection operates for an HV line
fault interrupting the Hydro One supply to a DESN TS LV bus to which DG is connected.
In the example, Figure 21, an LV bus DG island would only occur if the bus-tie breaker
BY was open and the L2 line protection opens LV transformer-breaker T2Y interrupting
the Hydro One supply to the Y bus to which DG1 – DG4 are connected.
Automatic reclosure is initiated from the HV line protection and the LV transformer-
breaker Transfer Trip or Remote Trip receive protections. The typical automatic reclose
time for a DESN TS LV transformer-breaker is typically 1 second, but that will only be
completed after the HV line protection at the main terminal TS automatically recloses,
typically in 5 seconds (may be as low as 2 seconds).
To prevent interference with a cumulative 3 second automatic reclosure self-clearing DG
anti-islanding protections must be capable of detecting an island condition within about
2.6 seconds.
This will be assured if the aggregate capacity of the islanded DG exceeds 50% of the
minimum load on the LV bus. Otherwise, TT will be required to be sent to disconnect
the DG whenever the LV transformer breaker and bus-tie breaker are open.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
132
DESN TS LV island
A DESN TS LV island forms when one or more main terminal line protections operate for
HV line faults, interrupting the Hydro One supply to a DESN TS to which DG is
connected.
In the example, Figure 21, a DESN TS LV would occur if transformer breakers T1B and
T2Y are both opened from operation of HV line protections, isolating all of the DG
connected to the DESN TS (DG1 – DG4).
Automatic reclosure is initiated from the HV line protection and the LV transformer-
breaker Transfer Trip or Remote Trip receive protections. The typical automatic reclose
time for a DESN TS LV transformer-breaker is typically 1 second, but that only after the
HV line protection at the main terminal TS automatically recloses, typically in 5 seconds
(may be as low as 2 seconds).
To prevent interference with a cumulative 3 second automatic reclose time self-clearing
DG anti-islanding protections must be capable of detecting an island condition within
about 2.6 seconds.
This will be assured if the aggregate capacity of the islanded DG exceeds 50% of the
total minimum load on the DESN TS. Otherwise, TT will be required to be sent to
disconnect the DG when all of the transformer breakers are open.
Wide-Area DG Island
A Wide-Area DG island can be formed when one or more main terminal line protections
operate for HV line faults, interrupting the Hydro One supply to all DESN stations and to
any HV-connected DS to which DG is connected.
For a two-circuit supply, both circuits would have to be interrupted to cause a wide area
DG island.
In the example, Figure 21, a wide area DG island would occur if supply to both HV lines
L2 and L2 are interrupted (a double circuit interruption). This is a relatively rare event
but can happen during wind storms or other adverse conditions.
For a single-circuit supply, interruption of the line protection for that circuit would cause a
Wide-Area DG island.
A Wide-Area DG island will occur if there is no TT from the main terminal station to the
DESN station or HV-connected DS or that TT fails causing the DESN station LV
breakers to remain closed. In that case, automatic reclosure of the HV lines will restore
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
133
Hydro One supply to all of the affected Wide-Area, typically in 5 seconds (may be as low
as 2 seconds) provided that there is no back-fed voltage detected on the HV lines by the
HV breaker automatic reclosure schemes.
A Wide-Area DG island may also occur if the next zone (upstream from Terminal
Stations) is tripped. This may occur if the net generation in the wide area network can
sustain the load at the time of occurrence.
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
134
E Appendix E – DGEO & LSBS Design Considerations
The following information is a design consideration for implementation of the DGEO and
LSBS signals for installations utilizing a High Voltage Interrupter or a High Voltage
Disconnect Switch (motorized Load Break Switch). This is for informational purposes only.
HVDS
CLOSE
Control HVDS
CLOSE
HVDS/b
Hydro One
DGn/b
DG2/bDG1/b
Feeder (3-Wire)
DG1
HVDS
Delta
PCC
DG2 DGn
Critical
Load
TT
DGEO
Telecom Tx
Rx
Hydro One
Feeder (4-Wire)
DG1
Wye
PCC
DG2 DGn
Critical
Load
TT
DGEO
Telecom Tx
Rx
HVI
Trip
Trip
Close
Close
pu
T2do
pu
T1dopu
T3do
HVI
CLOSE
Control HVI
CLOSE
HVI/bSpare
SpareSpare
pu
T2do
pu
T1dopu
T3do
HVDS on 3-Wire
HVI on 4-Wire
*HVDS - High Voltage Disconnect Switch
Based on Block ing the Low Set Inst at Hydro One for 5 seconds on a falling edge DGEO signal transition
HVI HVDS
TT Delay DGEO Delay Close Time Close Time PU Delay DO Delay PU Delay DO Delay PU Delay DO Delay
1 16ms 16ms 100ms 0ms 0ms 1s 0ms 0ms 6s
2 16ms 16ms 1s 0ms 0ms 1s 0ms 0ms 6s
3 30ms 250ms 100ms 0ms 0ms 1s 0ms 0ms 6s
4 30ms 250ms 1s 0ms 0ms 1s 0ms 0ms 6s
Example
#
Teleprotection Delay Timer T1 Timer T2 Timer T3
Figure 22: DGEO & LSBS Design Consideration
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
135
F Appendix F – Example of a Sequence of Events During Fault Conditions
The following two figures are a typical sequence of events during abnormal conditions, for both a transient fault and a permanent fault. Note: These diagrams assume that the DG facility requires Transfer Trip
and a HVI. This is for informational purposes only.
Figure 23: Sequence and Timing Diagram for Transient Faults
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
136
Figure 24: Sequence and Timing Diagram for Permanent Fault
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
137
G Appendix G – Confirmation of Verification Evidence Report (COVER Form)
The following is HONI‘s COVER Form. An updated version may be available and will be provided by HONI.
CONFIRMATION OF VERIFICATION EVIDENCE REPORT (COVER) [Distribution Connected Generation – (DCG)]
(Instructions provided on last Page)
Section 1 FACILITIES INFORMATION
NAME OF CUSTOMER
NAME OF FACILITY
PROPOSED ENERGIZATION DATE
HYDRO ONE OPERATING DESIGNATION
CLAIM NOTIFICATION
(Investment Planning #)
SUPPLY FEEDER DESIGNATIONS
Section 2 CONTACT INFORMATION
CUSTOMER CONTACT HONI COVER COORDINATOR CONTACT
Print Name:
Title:
Date:
Tel. #:
Email:
Print Name:
Title:
Date:
Tel. #:
Email:
[COVER - page 1 of 8]
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
138
Section 3 VERIFICATION-PROTECTION & CONTROL
Protection Group to verify: A, B, or A&B
Legend: C = Confirm
Results: P = Pass, F = Fail, N/A = Not Applicable
Pro
tect
ion G
roup
To v
erif
y
Leg
end
Res
ult
s
Init
ials
Dat
e
mm
/dd/y
yyy
Note
#
Is commissioning in compliance with the submitted
Commissioning plans?
Are reviewed relay settings applied?
Confirm that the following protection systems, as
applicable, have been verified to function as per the
design:
NOTE: Tests marked with an asterisks (*) require Hydro One
staff coordination
Line Protection
HV Breaker Failure Protection and Reclose
LV Breaker Failure Protection and Reclose
Transformer Differential
Transformer Backup Protection
Under and Over Frequency
Under and Over Voltage
Transfer Trip / Remote Trip *
Pilot Wire Protection *
Blocking Scheme Circuits *
Generation Rejection & Load Rejection Circuits *
Reverse Power
Gen. Prot. That trip HV Sync Breakers
Instrument Transformer (eg. CTS + CCVTs, etc.)
Monitoring Equipment (eg. DFR, SER, etc.)
Other (Specify)
[COVER - page 2 of 8]
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
139
Section 4A TELEMETRY TESTS BEFORE ENERGIZATION AT CUSTOMER OWNED TS
Confirm the following SCADA telemetry quantities,
where applicable:
Test Needed: D = to be Done
Legend: C = Confirm; Results: P = Pass, F = Fail
All Parts: N/A = Not Applicable
Tes
t
Nee
ded
Leg
end
Res
ult
s
Init
ials
Dat
e
mm
/dd/y
yy
y
Note
#
HV MW per transformer
HV MVAR per transformer
HV Phase to Phase Voltages (R, W, B)
LV MW per LV Bus
LV MVAR per LV Bus
LV Phase to Phase Voltages (R, W, B)
HV Under-Load Tap Changer Positions
HV Disconnect Switches/HV Circuit
Switchers/Breakers Open/Close Status
LV Transformer & Bus Tie Breakers Open/Close
Status
LV Capacitor Breakers Open/Close Status
Common Protection Trip Alarm each HV Circuit
Other (specify)
Section 4B TELEMETRY TESTS BEFORE ENERGIZATION AT CUSTOMER OWNED GS
Confirm the following SCADA telemetry quantities,
where applicable
Test Needed: D = to be Done
Legend: C = Confirm; Results: P = Pass, F = Fail
All Parts: N/A = Not Applicable Tes
t N
eed
ed
Leg
end
Res
ult
s
Init
ials
Dat
e
mm
/dd
/yy
yy
No
te #
MW Flows and Directions
MVAR Flow and Directions
Phase to Phase Voltages
HV switchers/HV breakers/Bus Tie Breakers
Open/Close Status
HV Line Disconnect Switches Open/Close Status
Synchronizing Breakers Open/Close Status
AVRs, PSSs status
Generation Rejection Selection Status
LV Breakers/Switchers, Open/Close Status
LV Synchronizing Breakers, Open/Close Status
Protection Trip Alarms
Other (specify)
[COVER - page 3 of 8]
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
140
Section 5 CONFIRMATION OF VERIFICATION-POWER EQUIPMENMT
Legend: C = Confirm, W = Witness
Result: P = Pass, F = Fail
All Parts: N/A = Not Applicable
Note, some of the following verification may require HONI staff witnessing.
Leg
end
Res
ult
Init
ial
Dat
e
mm
/dd/y
yyy
Note
#
Verify the HV disconnect switches/circuit switchers are suitable as an
isolation point per Utility Work Protection Code?
NOTE: Any future modifications to the isolation device(s) used to provide
supporting guarantees to HONI staff under the Utility Work Protection Code
must be re-witnessed by HONI personnel.
Confirm correct operation of the HV disconnect switches/circuit
switchers/breakers
Is closing time within manufacturer’s specification?
Is opening time within manufacturer’s specification?
Are the specified HV surge arrestors installed?
Confirm the power transformer Doble test results are within specification
Confirm power transformers connected correctly as per the design.
Confirm the DC system installed (ie battery, charger, dc panel, dc
monitoring)? Verified
Does the HV equipment (ie, disconnect switches, circuit switchers,
breakers, CVTs, CTs) have the appropriate voltage class and current
ratings as per the submitted Single Line Diagram?
Other (specify)
Name of Hydro One Witness:
Section 6 ELECTRICAL SAFETY
Legend: SD = Supporting Document, N/A = Not Applicable
Leg
end
Dat
e
mm
/dd/y
yy
y
Prior to energizing any new or modified customer or generator facilities, Electrical Safety Authority (ESA) must provide a Temporary Connection Authorization (Ontario Electrical Safety Code Article 2-014). Attach document.
Prior to final in-service of new or modified customer or generator facilities, ESA must provide Connection
Authorization (Code Article 2-012). Attach document.
All customers must provide a letter signed and stamped by a Professional Engineer registered in the province of
Ontario stating that their equipment and installation meets CSA and/or other applicable electrical safety standards, prior to ready for Service Date. Attach document.
[COVER - page 4 of 8]
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
141
NOTES: (For Sections 3, 4A or 4B, 5 & 6)
#: Comments: COVER Coordinator Concurrence To Connect:
Date Action Resolved: (dd/mm/yyyy)
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
By signing* this form, the customer
acknowledges that all required verifications
specified under this COVER document have
been completed and that the customer facility
design and operation meets the minimum
standards for customer facilities connected to a
distribution system, as per the Distribution
System Code.
Signature of Customer Representative (Note : Must be P. Eng)
Print Name:
Title:
Date:
Part I Completed COVER Coordinator Initials
*After signing the COVER, the customer shall submit it to the COVER coordinator with a copy to the Account Executive.
The COVER Coordinator has reviewed the
customer’s Certified COVER document and the
customer’s facility may be connected to the grid,
subject to Controlling Authority’s final review.
Signature of COVER Coordinator
Print Name:
Title:
Date:
The COVER coordinator shall forward (scan/fax) the completed document to the Controlling Authority to initiate the connection (for OGCC controlled distributed generators, the OGCC is the controlling authority. For other feeders the controlling authority will be Provincial Lines). The COVER coordinator shall contact (phone) the Controlling Authority, to notify him/her of the completed COVER. The COVER coordinator will ensure this document is placed within the Distribution Connection Agreement.
[COVER - page 5 of 8]
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
142
Section 7 CONFIRM ON POTENTIAL/ON LOAD CHECKS AT RATED SYSTEM
VOLTAGE
Legend: C = Confirm, W = Witness Result: P = Pass, F = Fail
All Parts: N/A = Not Applicable Leg
end
Res
ult
Init
ial
Dat
e
mm
/dd/y
yyy
Note
#
Are phasor (X-Watt meter) readings completed and analyzed by the
customer for Protection listed in Section 3?
Are phasor (X-Watt meter) readings completed and analyzed by the
customer for SCADA quantities listed in Section 4?
On Load SCADA Values confirmed consistent with test(s)
performed in Section 4A or 4B?
NOTES: (For Section 7)
#: Comments: COVER Coordinator
Concurrence:
Date Action Resolved:
(dd/mm/yyyy)
1.
2.
3.
4.
I/we acknowledge the completion of the COVER as noted and the deficiencies identified in the “NOTES” section have been resolved.
Signature of Customer Representative (Note: Must be P. Eng,)
Print Name:
Title:
Date:
[COVER - page 6 of 8]
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
143
Section 8 TEST SUMMARY REPORTS
In accordance with the Distribution System Code, Appendix F, for a Generation facility of Small size (pg.13), Mid size (pg.21), and Large size (pg.28), the Customer shall, at Hydro One's request, provide Hydro One with a
summary of testing results, including any certificates of inspection or other applicable authorizations or approvals
certifying that any of the Customer's new, modified or replacement facilities have passed the relevant tests and comply with all applicable instruments and standards referred to in the code. This information will be kept on file
for a period of (7) years by the Customer.
DISTRIBUTION LIST (WHEN ALL SECTIONS ARE COMPLETED):
Distribution Customer Business Relations Controlling Authority Customer Agent
Distribution Records (original) HONI COVER Coordinator
[COVER - page 7 of 8]
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
144
Customer Instructions for Completing the COVER form (DCG)
PART 1: PLAN
Step 1: Customer Information
Complete Facility and Customer Contact Information of the COVER Form by completing the highlighted
portions of Sections 1 & 2.
Step 2: Identify the Tests that the Customer Intends to Conduct
Complete Highlighted portions (Protection Group and Legend columns) of Sections 3, where applicable
Complete Highlighted portions of Section 4A or 4B (Test Needed and Legend columns)
Complete Highlighted portions of Sections 5 (Legend column) and 6 (Date Received column)
Note: The design review must be finalized prior to completing this step.
Step 3: Hydro One’s COVER Coordinator Review
Return COVER Form by email to the HONI COVER Coordinator listed in Section 2
The COVER coordinator will review the proposed and a respond to the acceptability of the proposed COVER
tests within 5 business days.
Note: The commissioning plan review must be finalized prior to commencing testing for the next step.
PART 2: PRE-ENERGIZATION
Step 4: Completion of Testing and Resolution of all Comments
Complete all applicable testing in Sections 3, 4A or 4B, 5 & 6.
Sign off the COVER, in section 6, by a Customer P.Eng Representative, and submit it to the COVER
Coordinator and Account Executive.
The COVER coordinator will review the certified COVER and recommend to the Controlling Authority (CA)
for connection to the grid by signing section 6 (for OGCC controlled distributed generators, the OGCC is the controlling authority. For other feeders the controlling authority will be Provincial Lines.)
Section 7 testing can only proceed when all salient comments have been resolved and tests completed for
Sections 3 to 6.
PART 3: POST-ENERGIZATION
Step 5: Final Potential and On-load Checks
Controlling Authority will provide authorization to connect to the grid (for OGCC controlled distributed
generators, the OGCC is the controlling authority. For other feeders the controlling authority will be Provincial
Lines.)
Complete and sign Section 7 when all parts of the COVER form are complete. (Note: cross readings to be performed within 5 business days of placing load on station)
Summary of testing results and certificates must be kept on file for a minimum period of 7 years by the
Customer (as indicated by IESO Market Rules, Chp.4, 5.1.3). Hydro One Networks Inc. may require this
information, on an exception basis.
[COVER - page 8 of 8]
Rev 0 February 2009
DISTRIBUTED GENERATION TECHNICAL INTERCONNECTION REQUIREMENTS Hydro One Networks Inc. INTERCONNECTIONS AT VOLTAGES 50KV AND BELOW
145
H Appendix H – Distribution Policy – Metering for Embedded Generators NOP 041
The following is HONI‘s Metering for Embedded Generators NOP 041 Policy. It contains the metering requirements for DG interconnection to HONI‘s distribution system.
146
147
148
149
150
151
152
153
154
155
156
157
Top Related