pnm approach to protecting overcompensated high-voltage...

© 2019 PNM and SEL

PNM Approach to Protecting Overcompensated High-Voltage Lines

Henry MoradiPublic Service Company of New Mexico

Kamal Garg, Mangapathirao V. Mynam, Eric Chua, and Jordan Bell

Schweitzer Engineering Laboratories, Inc.

• Overview of PNM system• Cabezon project summary• PNM protection standards• Series-compensated lines and protection challenges• PNM protection scheme• Laboratory tests and field events• Conclusion

Introduction

• 14,388 mi of transmission lines

• 69–230 kV primary voltage

• 46 kV subtransmission

• Large generation at San Juan, Four Corners substations

PNM System

115 kV230 kV345 kV

Rio PuercoCabezon

Four CornersSan Juan

HVDC Tie

HVDC Tie

SPP

Greenlee

Springerville

McKinley

• Compensation for Cabezon–Rio Puerco line is 170%

• Typical PNM compensation is 40–50%

• Shunt reactor provides reactive compensation

Cabezon Project Summary

Rio PuercoCabezonSan Juan

Four Corners

WW Linej63 Ω (109 mi)

CZ Linej19 Ω (34 mi)

FW Linej80 Ω (134 mi)

–j32.2 Ω

–j32.2 Ω

WW = San Juan–CabezonCZ = Cabezon–Rio PuercoFW = Four Corners–Rio Puerco

• Two relays at 115 kV and 230 kV and three relays at 345 kV

• Line current differential, POTT, and step-distance protection with backup overcurrent protection

• Quadrilateral distance protection for phase and ground Z1 = 70–80% of line impedance

Z2 = POTT forward direction, step-distance delay of 20 cycles

Z3 = POTT reverse direction

Z4 = Breaker failure, forward direction, delay of 60 cycles

PNM Line Protection Standards

• Backup instantaneous overcurrent element (phase and ground) at 15–20% of line

• Remote bus ground fault delay of 0.3–0.5 seconds • Three-pole tripping for most applications


115 kV Substation 1

115 kV Substation 2

Bus Protection Zone

115 kV Line With Tap Transformer

Transformer Protection Zone

• Differential protection uses positive-, negative-, and zero-sequence elements

• 115 kV lines use tapped load and do not use negative-sequence differential elements

• Future protection will include breakers at tapped substations, allowing system to be restored once transformer fault is cleared


86BF/CB3

86BF/CB2

86BF/CB186B/

B1–BCL CB1–BCL CB2–BCL All Bus 1 CBs

–BCL CB1–BCL CB2–BCL CB3

–BCL CB2–BCL CB3–BCL All Bus 2 CBs

Bus 1 Bus 2

Transformer 186T/T1

Line 1 Line 2

Line 3

CB1 BF (line and bus)1. Line 1 R1, R2, R32. Bus 1 RX1, RX2

Line R11. Re-Trip CB12. Trip CB23. DTT R2, R3 Line 14. TTR Remote End5. DTT RX1, RX2 Bus 16. Assert 86BF/CB1

Bus 1 R11. Re-Trip CB12. DTT RX2 Bus 13. DTT R1, R2, R3 Line 14. Assert 86BF/CB1

1 2 3

PNM Protection Standards

Shunt Reactor

UHS RelayIX IW

Shunt Reactor Reactor

Protection

87, REF, 50FB, 67Q

IS

IT

IY 1

Phasor-Based Relay

50BF, 21, 87

IX

IW

PNM Protection Standards

80

60

40

20

40 60

–20 Capacitor Bank Set = 4 kAFault Current Through Capacitor = 2.87 kAZ = 20.03 – 32.1 = ~–12.0 Ω

–20 20

Relay Response: Zone 2 Tripped. Delay = 0.33 s.B-C UNIT: Zone 2 Tripped.C-A UNIT: Zone 2 Tripped.A-B UNIT: Zone 2 Tripped.More details in TTY window.

FAULT DESCRIPTION:Bus Fault On: 0 RIO_PUERCO 345 kV 3LG

PHASE A0.0 + j –32.10.0 + j –32.1

PHASE B0.0 + j –32.10.0 + j –32.1

PHASE C0.0 + j –32.10.0 + j –32.1

EQUIVALENT IMPEDANCE OF MOV-PROTECTED SERIES CAPACITORS THAT FIRED [CHM]:

CAP PW 345.0kV – RIO_PUERTO 345.0kVCAP WW 345.0kV – RIO_PUERTO 345.0kV

–40

• Current and voltage inversion

• Impedance estimation

• Differential protection

Compensated Lines and

Challenges Rio PuercoCabezonSan Juan

Four Corners

WW Linej63 Ω (109 mi)

CZ Linej19 Ω (34 mi)

FW Linej80 Ω (134 mi)

–j32.2 Ω

–j32.2 Ω

WW = San Juan–CabezonCZ = Cabezon–Rio PuercoFW = Four Corners–Rio Puerco

Algorithm Phasors Incremental Quantities Traveling Waves

Signal spectrum of interest 40–70 Hz 0.5 kHz 100 kHz

Filtering

Sampling 16 s/c 10 kHz 1 MHz

Line theory VF = V – ZI

Operating time 1 cycle A few milliseconds 1–2 ms

Elements Z1P, Z1G, 32G, 32Q, and more TD21, TD32 TW87, TW32

Phasor and Time-Domain PrinciplesSimilarities and Differences

• Phasor-based protection

• Four quadrilateral zones

• POTT

• Line current differential settings Positive-sequence current = 600 A

Maximum line loading 1,004 MVA = 1,680 A (600 A / 2,000 A = 0.3 pu)

Zero-sequence element = 10–15% unbalance (10% • 2,000 = 200 A = 0.1 pu)

Negative-sequence element = 25% of 500 A = 0.25 pu

Reach Selection

• TD21 Phase and ground elements set to 75% and 70%,

respectively

External series compensation = Y

• TD32 TD32ZF = 0.3 • strongest impedance for fault at remote bus

TD32ZR = 0.3 • line impedance including series capacitor

Reach Selection – UHS Time Domain

• POTT – TP67P and TP67Gselected based on maximum incremental current caused by series capacitor switching

• TW87 – TP50P set above line charging current and below minimum remote bus fault current (select margin of 50–75%)

Reach Selection – UHS Time Domain

where:ZS1 = strongest local source impedanceZL1 = line impedanceZT1 = strongest equivalent remote source impedance

Rio Puerco

CabezonSan Juan

Four Corners

5–95% 5–95%

5–95%

5–95%

West Mesa

5–95%

B-A• Model system• Test internal and

external faults

Lab Testing

Line Percent (%)

Per

cent

(%) o

f Tot

al F

aults

0102030405060708090

100

• Phasor-based• Time domain

Lab Testing

Line Percent (%)

Per

cent

(%) o

f Tot

al F

aults

0102030405060708090

100Rio PuercoCabezon

Results Summary

10

16

12

1820

14

Ave

rage

Trip

Tim

e (m

s)

0

6

2

8

4

0Fault Location (% of line)

10 30 50 70 9020 40 60 80 100

Phasor-Based

UHS-Based

Rio PuercoCabezon

–400Vol

tage

(kV

)

Time (ms)–50 0 50 100

–2000

200400

TD32FKEY

PTRX

–4,0000

4,000C

urre

nt (A

)IC

IA IB

VCVA VB

External Faults –Cabezon

Date Fault Type Location

10/2/2018 CG Behind San Juan terminal


8/13/2018 CG Four Corners–Rio Puerco line

External Faults –CabezonΔ

Vol

tage

(V)

–100

0

100

TD32F

–20

0

20

Δ R

eplic

a C

urre

nt (A

)

–2 0 2 84 6 10Time (ms)

–2 0 2 84 6 10Time (ms)

Torq

ue (V

A)

–100–50

050

100150

Inte

grat

ed

Torq

ue (V

A)

–104–102

0102104

–2 0 2 84 6 10Time (ms)

–2 0 2 84 6 10Time (ms)

Operating

Operating

Forward Restraining

Reverse Restraining

Forward Restraining

Reverse Restraining

Time (ms)–20 20 400 60 80

PTRXKEY

TD32R

–400–200

0200400

Vol

tage

(kV

)–4,000

0

4,000

Cur

rent

(A)

–2,000

2,000 ICIA IB

VCVAVB

External Faults –Rio Puerco

Date Fault Type Location



8/13/2018 CG Four Corners–Rio Puerco line

Δ V

olta

ge (V

)

–100

0

150

TD32R

–20

0

15

Δ R

eplic

a C

urre

nt (A

)

–50

50100

–2 0 2 84 6 10Time (ms)

–2 0 2 84 6 10Time (ms)

–5

510

External Faults –Rio Puerco

Torq

ue (V

A)

–200–150–100

–500

50

Inte

grat

ed

Torq

ue (V

A)

–105

0

105

–2 0 2 84 6 10Time (ms)

–2 0 2 84 6 10Time (ms)

Operating

Operating

Forward Restraining

Forward Restraining

Reverse Restraining

Reverse Restraining

External Faults – 8/13/2018Rio Puerco End

ICWIBW

R32P67G3–400V

olta

ge (k

V)

–3,000

Cur

rent

(A)

0200400

0

2,000

Time (ms)500 100 150

3,000

VCYVAY VBY

–50

–200

1,000

–1,000–2,000

IAW

Time (ms)20 400 60 80 100

KEY67G2Z2G

–400

Vol

tage

(kV

)

–200

0

200

400–3,000–2,000–1,000

01,0002,0003,000

Cur

rent

(A) ICW

IAWIBW

VCYVAY VBYExternal Faults –8/13/2018

Cabezon End

• 170% series-compensated line

• Protection challenges for series-compensated lines

• Phasor- and UHS-based relays

• PNM protection standards and set point selection

• Laboratory tests to validate set points

• Phasor-based relay operating time ~16 ms, UHS relay operating time ~2–4 ms

• Field event analysis verifying performance

Conclusion

Questions?

pnm approach to protecting overcompensated high-voltage...

Documents