© SEL 2017Copyright © SEL 2017

Niraj ShahSPS Branch of SEL Engineering Services Inc.

POWERMAX® [ˈpou (ə)r ˈmaks] noun: a system designed to maintain stability

• POWERMAX – Power Management System Introduction

• POWERMAX – Functionalities (IDDS, LSP, GCS, A25A)

• POWERMAX – Simulators

• MOTORMAX – LV Motor Management System Introduction

Agenda

• POWERMAX – Power Management System Introduction

• POWERMAX – Functionalities (IDDS)

• POWERMAX – Simulators

• MOTORMAX – LV Motor Management System Introduction

Agenda

POWERMAX Functions

HMI /SCADA

IDDS GCS A25A andTie Flow

High-SpeedLoad

SheddingEngineering Management

What Is an IDDS?110 kV

Substation 1

25 kVA

Island

DG1

B

DG2

D

120 V

–

C

DG3 ~

• Islanding detection – detects islanding condition when microgrid disconnects from utility power system

• Decoupling – microgrid capability of detecting an ongoing utility disturbance and intentionally islanding microgrid

Islanding Detection and Decoupling

• Direct transfer trip

• Local-area-based Rate-of-change of frequency (81R) and fast rate-of-change of

frequency (81RF)

Undervoltage / overvoltage and underfrequency / overfrequency

• Wide-area-based Angle-based

Slip and acceleration-based

IDDS Schemes

81RF Characteristic

Trip Region 1

Trip Region 2

0.1–0.2

–0.10.2

+81RFRP

+81RFDFP

–81RFRP

DFDT (Hz per second)

DF (FREQ – FNOM) (Hz)–81RFDFP

Wide-Area-Based Schemes

Relay 1 Relay 2PMU Data

MicrogridUtility Grid Transmission System

(1) (2)k k kAngle V V= δ = ∠ −

k k k 1 MRATESlip frequency S ( )

360−= = δ − δ

( )−= = −k k k 1Acceleration A S S MRATE

Slip Acceleration CharacteristicDetecting an Islanding Event

Islanded

Connected

Acceleration

Slip Frequency0

0

Islanded

Example Industrial Power System

400 kV Transmission Substation

400 kV Substation

220 kV Generation Substation

220 kV Load Substation220 kV Load

Substation

220 kV Load Substation

220 kV Generation Substation

220 kV Load Substation

Utility

Microgrid

Case A 81RF ElementR

ate

of C

hang

e of

Fre

quen

cy

(Hz

per s

econ

d)0.60.4

0.0–0.2–0.4–0.6–0.8

0.2

–0.04 –0.02 0.00 0.02 0.04 0.06Frequency Difference (Hz)

Case A Angle Difference Element

1.5

1.0

0.5

0.0

–0.550 150100 250200 300 350

Ang

le D

iffer

ence

(d

egre

es)

Samples (each equal to 20 milliseconds)

Case AIDDS Blocked

Loss of 1,200 MW of

generation followed by load shedding

Case Frequency Rate (Hz / s)

Export (MW)

Detection Time(ms)

B3 1.5 260 900B5 -1.8 800 720B6 0.6 800 1,380

Utility DisturbanceDesired Condition: Detect and Decouple

Utility DisturbanceDesired Condition: Detect and Decouple

IDDS Trip

IDDS Trip

Positive Threshold

Start of Event

X: –1.164Y: –1.803

X: 1.218Y: 1.456

Rat

e of

Cha

nge

of F

requ

ency

(H

z pe

r sec

ond)

Frequency Difference (Hz)

–2

–1

0

1

2

3

–1.5 –1.0 –0.5 0.0 0.5 1.0 1.5

Microgrid frequency returns to stable pointNegative Threshold

IDDS Trip

X: 1.392Y: 0.3503

Case B6

Case B3Case B5

81RF Element

Case Export / Import (MW)

Detection Time(ms)

D1 520 160D2 70 300D3 0 500

Angle-Based IDDSDesired Condition: Detect and Decouple

Angle-Based IDDSDesired Condition: Detect and Decouple

Threshold

IDDS Trip

X: 98, Y: 0.0296

Angle Difference ElementA

ngle

Diff

eren

ce (d

egre

es)

Samples (each equal to 20 milliseconds)85 90 95 100 105 110 115 120 125

–15

–10

–5

0

5

10

15 X: 106, Y: 18.06

IDDS Trip

Start of Event

Threshold

X: 113

Y: 15.64IDDS Trip

Case D1 (P ~ 520 MW) Case D2 (P ~ 70 MW) Case D3 (P ~ 0 MW)

X: 123

Y: –12.67

Case D1Slip and Acceleration Characteristic

Start of Event

Microgrid Frequency Returning to a Stable Point After IDDS

Trip and Generation Shedding

Positive Threshold

Rat

e of

Cha

nge

of F

requ

ency

(H

z pe

r sec

ond)

Frequency Difference (Hz)

2

1

0

–1

–2

–4

–3

–5

–1.5 –1.0 –0.5 0.0 0.5 1.0 1.5

IDDS Trip Due to Angle Difference Element

X: 0.1695Y: 1.971

Negative Threshold

Limit 1Limit 2Case D1

81RF Element

Case E1IDDS Rides Through

(No Decoupling)

Single-phase fault and fault isolated by

opening Line 1

Case E1 81RF Element

Rat

e of

Cha

nge

of F

requ

ency

(H

z pe

r sec

ond)

0.3

0.0

–0.2

0.2

–0.02 –0.01 0.00 0.01Frequency Difference (Hz)

0.1

–0.1

Ang

le D

iffer

ence

(d

egre

es)

2.5

1.0 50 100 150 200Samples (each equal to 20 milliseconds)

2.0

1.5

250 300

Angle Difference Element

Case E1

–0.3

Criterion DTT Local-Area Wide-Area

Remote communications available Effective Effective Effective

Remote communications not available Not effective Effective Not effective

Local generation matches local load during unintentional islanding Effective Not effective Effective

Several remote side breakers that can create islanding Not effective Effective Effective

Utility disturbances and no breaker opening Not effective Effective Partially effective

Lessons LearnedRelative Effectiveness of Schemes

• Sustainable electrical grids require fast and reliable IDDS combined with load and generation balancing

• DTT provides fastest speed for islanding detection

• Local-area-based 81RF provides reliable decoupling for utility disturbances

• Wide-area-based synchrophasor schemes detect islanding condition during very low power flow conditions

Summary

Questions?