IEEE Generator Protection
-
Upload
shashank11 -
Category
Documents
-
view
409 -
download
8
Transcript of IEEE Generator Protection
1
Generator Management Relay
Protection, metering, and monitoring functions for generators.
Presented by:
John Levine, P.E.Levine Lectronics and Lectric, Inc.
[email protected] 565-1556
2
Outline
Overview
Theory
Wiring
Security
3
Generator Protection
What a Generator looks like
4
Generator Protection
5
Overview
6
Why Upgrade? Generator and Transformer
• Existing generator and transformer protection (more than 5 years or non-digital) may:– Cause protection security issues
• Tripping on through-faults, external faults, swings, load encroachment and energizing
– May lack comprehensive monitoring and communications capabilities• Not provide valuable forensic info that can lead to rapid restoration
– Not be up to ANSI/IEEE Standards!– Insurance, Asset Reliability and Personal Liability Issues
• C37-102: Guide for the Protection of Synchronous Generators
• C37.91: Guide for Transformer Protection
7
Product Overview• Ideal Protection for Induction and
Synchronous Generators at 25, 50 and 60Hz
• Complete Generator Protection including:
• Generator Stator Differential
• 2 or 3 Zone Distance Backup
• 100% Stator Ground
• High speed sampling, 12 samples per cycle
• Drawout Case Installation
• Powerful Fault Recording: Waveform, Sequence of Events
• Ethernet and Serial Communications
• Metering of all important parameters
Generator Management Relay
8
Theory
9
Show Generator Theory General Overview and Typical System from Training CD
10
Generator Protection
• Internal and External Short Circuits
The "Wild"PowerSystem
G
Exciter
StatorGround
StatorPhase
SystemGround
SystemPhase
11
Generator Protection Review
– Abnormal Operating Conditions• Loss of Synchronism
• Abnormal Frequency
• Overexcitation
• Field Loss
• Inadvertent Energizing
• Breaker Failure
• Loss of Prime Mover Power
• Blown VT Fuses
• Open Circuits
12
Generator Protection
• Abnormal Operating Conditions
The "Wild"PowerSystem
G
Exciter
Loss of FieldLoss of Field
Overexcitation
Overexcitation
Overexcitation
OpenCircuits
Loss ofSynchronism
InadvertentEnergizing,Pole Flashover
AbnormalFrequency
AbnormalFrequency
BreakerFailure
ReversePower
OverPower
13
IEEE PSRC Survey
– Conducted in early ’90s, showed many areas of protection lacking
– Unwillingness to upgrade:• Lack of expertise
– To recognize deficiency
– To perform the work
• “Generators don’t trip” (wrong)
• Operating procedures will save the day
PSRC = Power System Relay Committee
14
ANSI/IEEE Standards
• Latest developments reflected in:– Std. 242: Buff Book
– C37.102: IEEE Guide for Generator Protection
– C37.101: IEEE Guide for AC Generator Ground Protection
– C37.106: IEEE Guide for Abnormal Frequency Protection for Power Generating Plants
These are created/maintained by the IEEE PSRC & IASThey are updated every 5 years
15
Small Machine Protection IEEE Buff Book
• Small – up to 1 MW to 600V, 500 kVA if >600V
32 Reverse Power
40 Loss of Excitation
51V voltage restraint
51G Ground overcurrent
87 Differential
16
Small Machine Protection IEEE Buff Book
• Medium – up to 12.5 MW
32 Reverse Power
40 Loss of Excitation
46 Negative Sequence
51V voltage restraint
51G Ground overcurrent
87 Differential
17
Small Machine Protection IEEE Buff Book
• Large – up to 50 MW
32 Reverse Power
40 Loss of Excitation
46 Negative Sequence
49 Thermal Overload
51V voltage restraint
51G Ground overcurrent
64 Ground Relay
87 Differential
18
• Unit Connected,
• High Z Grounded
Large Machine ProtectionIEEE C37.102
32 Reverse Power
40 Loss of Excitation
46 Negative Sequence
49 Thermal Overload
51V voltage restraint
51G Ground overcurrent
64 Ground Relay
87 Differential
19
HYBRID SYSTEM
20
Protection Functions
Protection Functions Include:
• Generator Stator Differential• Backup Distance Protection• 100% Stator Ground• Generator Unbalance• Loss of Excitation• Accidental Energization• Breaker Fail • Phase Overcurrent – Voltage Restraint• Neutral Inst. / Timed Overcurrent• Neg. Sequence Overcurrent• Under / Over Voltage• Under / Over Frequency• Generator Thermal Model• RTD Temperature• Overexcitation – Volts/Hertz
21
Generator Protection
22
Generator Protection with GSU Wrap PTs on Low Side
23
Generator Protection with GSU Wrap PTs on High Side
24
Generator Protection PTs on Low Side
25
Desirable Attributes - Generator
– Reverse Power (32)• Should be sensitive to 0.05 pu to properly detect motoring in large steam turbines
– Existing E/M and Static relays not sensitive enough
– May cause shutdown difficulties
– Negative Sequence (46)• Should be sensitive to low values to detect open poles/conductors on system after GSU
– Existing E/M and Static relays not sensitive enough
• Long time low level events may cause excessive rotor heating, thermal tripping and damage rotor
– 100% Stator Ground (59N / 59D)• Protects all of the stator winding
– Existing schemes typically only see 90%
– Stop low level fault near neutral from degrading into a high level fault and causing large amounts of damage
– Very secure
26
Desirable Attributes - Generator
• Inadvertent Energizing (50/27)
– High speed tripping of unit after breaker accidentally closed on dead machine, also pole flashover prior to syncing
• Most existing schemes do not incorporate
– Many schemes fail due to complexity (reliance on breaker auxiliary switches, yard distance relays, etc.
– If breaker is not tripped rapidly, mechanical and electric damage can occur to machine in fractions of a second!
– Pole flashovers must be cleared by high speed breaker failure, as the breaker is open!
27
Line – Ground faults – Delta Connected Generator
28
Line – Ground faults – Wye Connected Generator
29
Protection Functions
Generator Stator Differential• Stator Phase Differential• Dual Slope Percent Restraint Operating
Characteristic • Directional Supervision under saturation
conditions
Distance Backup Protection• 2 or 3 Zone Mho Distance Protection• Backup for primary line protection• Configurable Reach and Angle Distance
Characteristic
100% Stator Ground Protection• 95% Fundamental OverVoltage• 15% Third Harmonic UnderVoltage
Dual Slope Phase Differential
Two Zone Distance Backup
30
Protection Functions
Voltage Restraint Overcurrent
Undervoltage Trip Curves
Voltage Protection• Phase Overvoltage• Phase Undervoltage• Neutral Overvoltage (fundamental)• Neutral Undervoltage (3rd Harmonic)• Voltage Phase Reversal
Current Protection • Phase, Ground and Negative Sequence Overcurrent Tripping
• IEC, ANSI , IAC and Customizable Overcurrent Curves
• Voltage Restraint increasing sensitivity under low voltage conditions
Frequency Protection• Overfrequency• Underfrequency
31
Protection Functions
Loss of Excitation
Thermal Protection• Generator Thermal Model• RTD Alarming and Tripping• RTD Biased Thermal Model
Inadvertent Energization • Prevents Accidentally Closing a Stopped Generator onto a Live Line
• Armed when Generator is Offline and Voltage is below a pre-set level
Loss of Excitation (show Training CD)
• Uses Impedance Circle for loss of excitation detection• 2 Zones for fault detection and control
Volt/Hertz (Overexcitation)• Detects changes in the Volts/Hertz ratio of the generator or associated transformer
Thermal Model – Voltage Dependant Overload Curves
32
Wiring
33
34
35
36
37
Example
38
Security Audit Trail
• Date and time of hardware, firmware or setting changes to your relays
• Logging of the MAC address of computers and users making settings changes
• Track method of how settings changes were made (i.e. keypad, serial port, ethernet)
Security strategy – conforms to industry and regulated guidelines
• Date/time security report was generated
• Description of the GE Multilin Relay
• Summary of the last time the configuration was changed
• History of last 10 occurrences the configuration was changed
Enhanced Security
Prevents Unauthorized Access and Provide Traceability