Application of Digital Relay Protection on APUA.....

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Application of Digital Relay Protection on APUA

T&D Network

Li Zhengrong ²Substation Maintenance & Protection Engineer

Andre Matthias²Division Manager

Electricity/ transmission & Distribution Division

Antigua Public Utilities Authority

July 23-25, 2002

2002 Carilec Engineers ConferenceMontego Bay, Jamaica

Presented by:



Application of Digital Relay Protection on APUA

T&D Network

Application Digital Relay Protection

Communication Software Workstation

69kV Lines 11kV Feeders

KEY WORDS



1.General information

� The total installed generation capacity is 64.5MW and the present peak load

is 34.8MW;

� Eight (8) 69kV transmission lines operating in close-ring are 59.2kM in

length;

� Twenty-two (22) 11kV feeders radiating and covering entire Island are

539kM in length;

� Twelve (12) 69/11kV power transformers at seven (7) step-up/-down

substations possess a total installed capacity of 160.34MVA.

1.1 Introduction of APUA electric power system



1.General Information

1.2.1 11kv primary feeders:

a. Under-frequency protection feature for load-shedding;

b. One-shot re-closing

c. fuse-saving scheme

1.2 . Requirement for relay upgrade




1.2.2 69kv transmission lines:

a. eliminate protection dead zones

b. reduce duration of faults on power system

c. prevent equipment damage

d. differentiate max. load current from min. fault current

e. avoid misoperation of current balance protection.

1.2 . Requirement for relay upgrade (continued)




� Replacing electromagnetic distance relay protections on 69kv transmission lines

with 351 digital relays was done in 2000;

� Replacing electronic relays on 11kv feeders with DFP-100 and 351/551 digital

relays was done in 2001;

� Replacing differential relays on 69/11kv power transformers with SEL-587 relays is

in progress.

� The entire upgrade project that was from project design, settings calculation to relay

programming, installing and testing, was carried out by APUA staff .

1.3 Relay protection upgrade project



2. Application of Digital Relays on 11kV Primary Feeders

2.1.1 Phase-to-phase protection(positive-sequence protection 50P)

� Instantaneous over-current with time-delay(50PH )� Time-definite over-current (50PL)

2.1.2 Earth fault protection (zero-sequence protection 50N)

� Time-definite zero-sequence over-current (50N)

2.1.3 Under-frequency protection for load-shedding (81U1,81U1T)

2.1.4 re-closing

� One-shot re-closing (SH0) is activated only under phase-to-phase

fault

2.1 Fundamental Protection Feature



2. Application of Digital Relay on 11kV Primary Feeders

A.

Phase-to-phase protection(50P)

� Instantaneous over-current with time-delay(50PH), protectsentire primary feeder and primary side of distribution power transformers;

� Time-definite over-current (50PL) as backup protection of 50PH and fuse links, protects entire primary feeder and bothsides of distribution transformers.

Protection zone is shown in Figure 1 .

2.2 Definition of protection zone



Figure 1 phase-to-phase over-current protection

50PH

50PL

Relay Solid link

2.2 Definition of protection zone (continued)


Fuse link 1 Fuse link 2

Fuse link 3




B. Earth fault protection(50N)

� Time-definite zero-sequence over-current (50N) as backup protection of

fuse links, protects entire primary feeder and primary sides of

distribution transformers under earth fault circumstance.

� Protection zone is shown in Figure 2 .




Figure 2 earth-fault protection

50NH

Relay Solid link

2.2 definition of protection zone (continued)


Fuse link 1

Fuse link 2




C. Fuse link protection

� Fuse link immediately clears faults on both sides of protected

distribution transformer;

� Fuse link clears faults on protected branch of primary line.

Protection zone is shown in Figure 3.




Figure 3 protection zone of fuse link

Fuse link 1

Relay Solid link

2.2 definition of protection zone (continued)


Fuse link 3

Fuse link 2




A. Fuse link

� Fuse link blows out first to clear faulted branch or distribution transformer

B. Phase-to-phase protection(50P)

� Instantaneous over-current with time-delay(50PH) acts as backup protection

for fuse links;� Time-definite over-current (50PL) performs as remote backup protection

for both 50PH and fuse links.

2.3. The trip-saving scheme




C. Earth fault protection(50N)

� Time-definite zero-sequence over-current (50N) acts as backup protection

for fuse links.

D. One-shot reclosing (SH0)

� One-shot reclosing is activated under phase-to-phase faulty condition

(Notice: Consider to avoid a human being or an animal to be shockedtwice while carelessly touching a live conductor; one-shot re-closing is

replaced by manual re-closing under earth fault circumstance).

2.3 The trip-saving scheme(continued)




A. Phase-to-phase protection(50P)

� Instantaneous over-current without time-delay(50PH) will immediately

clear fault and then be locked by one-shot re-closing after circuit-

breaker tripping.� After 5 seconds, the feeder will be closed by one-shot re-closing

successfully if the temporary fault disappears at once;

� The permanent fault area will be isolated by related fuse link from

entire feeder, or time-definite over-current (50PL) trips entire feeder

B. Earth fault protection(50N)

� Functions as same as that in the trip-saving scheme

2.4 The fuse-saving scheme




Date: December 13, 2001

Cause: a freak storm

Total tripped Feeders: 11

Total trip times: 19

Phase-to-ground fault: 1 temporaryPhase-to-phase fault: 18 (12 temporary; 6 permanent)

2.5 Recorded trips of 11kv feeders




a. Under-frequency protection with under-voltage supervision:

Use under-frequency trip (81UT) with under-voltage supervision(27U)logic to eliminate unnecessary trip under phase-to-phase fault.

The trip logic is programmed as: trip=81UT*!27U

b. Circulatory change of trip sequence:The different under-frequency settings and same over-current settings can

be preset in each of 6 groups for circulatory change of trip sequence by

activating certain settings group.

2.6 Under-frequency protection for load-shedding



3. Application of Digital Relay on 69KV Transmission lines

3.1.1 Phase-to-phase protection (positive-sequence protection 50P)

� Directional instantaneous over-current without time-delay(Zone one 67P1)

� Directional instantaneous over-current with time-delay (Zone two 67P2)

� Directional time-definite over-current protection (Zone three 67P3)

3.1 Protection Feature




3.1.2 earth fault protection(zero-sequence protection 50N)

� Directional instantaneous over-current without time-delay(Zone one 67N1)

� Directional instantaneous over-current with time-delay (Zone two 67N2)

� Directional time-definite over-current protection (Zone three 67N3)

� Directional time-definite over-current protection for phase-loss supervision

(Zone four 67N4)

� Zero-sequence over-voltage with time-delay (59N) as a complement

3.1 Protection Feature (continued)




3.1.3 re-closing

� Synchronize-check (25A) or non-voltage check (27S) to initiate

re-closing

� One-shot re-closing (SH0) is activated only under phase-to-phasefault

3.1 Protection Feature




GG GG GGG

Friar¶s Hill

Cassada

Crabbs

LavingtonSwetesBelmontUnion Road

13 2

1311

456

78 9 12 1415

K 3

10

16

TmaxOLD=2.60Seconds

TmaxNOW=1.85Seconds

TmaxOLD=2.60Seconds

TmaxNOW=1.85Seconds

Figure 4 Clockwise in blue starts at # 1 CB and ends at #11/13 C.B

Anticlockwise in red starts at #10/12 and ends at #14 C.B

3.2 Clockwise /Anticlockwise Coordination Route




3.3 Reduce Duration of Fault Clearing

a. The recommended time difference between adjacent

relays is 0.4-0.6 Seconds for electromagnetic relays and

0.25-0.3seconds for digital/ electronic relays;

b. The maximum time setting was coordinated as 2.60

seconds for previous electromagnetic distance relays

numbered 11,13 and 14, and that for SEL digital relay

protections at same location is 1.85seconds.

c. The net decrease of time settings between two kinds of

protections is 0.75seconds.




3.4.1 Zero-sequence over-voltage (59N) as a complement at some

lines while close-ring of transmission lines is opened at somecertain point

Case A CB #1 opens (see Figure 5)

Case B CB #9 opens (see Figure 6)

3.4.2 distinguish maximum load current ILD

from minimum faultcurrent IF at 69kV section breaker # 15 by load-encroachmentLogic (see Figures 7&8)

3.4 Eliminate protection dead zone




3.4 Eliminate protection dead zone(continued)

GG GG GGG

Friar¶s Hill

Cassada

Crabbs

13 2

1311

456

78 9 12 1415

K (1.0)

10

16

Earth fault

O pened

Figure 5 Case A circuit-breaker #1 opens

YO/D YO/D YO/D YO/DY/YOY/YOY/YOY/YO

O/V




3.4 Eliminate protection dead zone(continue)

GG GG GGG

Friar¶s Hill

Cassada

Crabbs

13 2

1311

456

78 9 12 141510

16

Figure 6 Case B circuit-breaker #8 or 9 opens

YO/D YO/D YO/D YO/DY/YOY/YOY/YOY/YO

O pened

O/VO/VO/V

O/V O pened

K (1.0) -----Earth fault

K (1.0)

K (1.0) K (1.0)

K (1.0)





Figure 7 Distinguishing IFMIN from ILDMAX at circuit-breaker #15

GG GG GGG

Friar¶s Hill

Cassada

Crabbs

13 2

1311

456

78 9 12 1415K (2)

10

16

IF=158A

ILD=219A

IF2=202A IF=58A

IF=100A





Figure 8 Distinguishing IFMIN from ILDMAX by load-encroachment Logic

X

R

load

fault

Load outLoad in



3. Application of Digital Relays on 69KV Transmission lines

3.5.1 In the previous designs, the closing or tripping coils or relatedrelays were frequently burned out by overheating when system

operator switched circuit-breaker by SCADA under followingabnormal conditions:

a. Substation¶s D.C. low-voltage (less than 70%), or

b. The stuck output contact of auxiliary relay, or

c. Mechanism jamming of circuit-breaker .

3.5 Prevent equipment damage from abnormal condition




3.5.2 Measures being taken to prevent damage of

facilities:

a unifying close/open (or trip) commands between SCADA and

relays;

b. programming new relays and improving wiring connection;

c. programming output of close or open commands.

3.5 Prevent equipment damage from abnormal condition(continued)




3.5 Prevent equipment damage from abnormal condition(continued)

SCADA

SystemDigital

Relay

69kV

circuit-breaker

Protection

relay

Figure 9 change of control/protection logic




3.6.1 Interlocking balance current protection on 69kV double lines

while single line operates (see Figure 10)

3.6.2 Speed-up tripping of Zone two (67P2) while re-closing onto permanent faulted line (see Figure 11)

3.6.3 Anti-pump of circuit-breaker (see Figures 12)

3.6 Provide flexible Logic functions




3.6 Provide flexible Logic functions (continued)

Figure 10 Interlocking balance current protection on 69kV double lines

G1G2

Trip circuit

Output 1 Output 2 52A1 52A2 B/C trip

1

24

3

B/C &351B/C &351

B/C &351 B/C &351O penO pen

Close Close

Output1 ²output contact of #1 351 relay (=67P2)

Output2²output contact of #2 351 relay (=67P2)

52A1 ²auxiliary contact of #1 circuit-breaker

52A2 ²auxiliary contact of #2 circuit-breaker

B/C ²balance current protection

B/C trip²trip contact of balance current protection




3.6 Provide flexible Logic functions (continues)

Figure 11 Speed-up tripping of Zone two (67P2) while re-closing onto permanent faulted line

GRelay #2

67P1Relay #1

Trip logic:

Trip= 67P1T+67P2T+67P3T+67P2*\SH0

Where: 67P1T²timer of zone one (67P1)

67P2T²timer of zone two (67P2)

67P3T²timer of zone three (67P3)

\SH0 ²declining edge of one-shot reclosing

K

67P3

67P2




Figures 12 Anti-pump of circuit-breaker under permanent faulty condition

3.6 Provide flexible Logic functions (continued)

SCADA or

Manual Closing

command

Status of C.B

(No logic)

Closing commandWith logic

Status of C.B

(with logic)

T67P1T

TLDO

TCL

TCL

T67P1T

TOP ² inherent open time of circuit-breaker

TCL ² inherent close time of circuit-breaker

T67P1T ² timer of relay zone one (67P1)

TLDO ² drop-off timer of logic-controlled contact (TCL +T67P1T+ TOP> TLDO> TCL)

TOP

TOP




3.7 Provide reliable and useful data information

a. The magnitude and phase angle of three-phase current and voltage;

b. Dual-directional single/three-phase active/reactive power and energy;

c. Dual-directional load flow;

d. Power factor and work frequency;

e. DC voltage;

f . Pre-fault and fault current and voltage;

See downloaded data information



CRB-CAS #1 69KV LINE Date: 05/29/02 Time: 11:13:55.618 CRABBS SUBSTATIO N

A B C N G

I MAG (A) 77.534 74.927 78.517 0.387 0.424

I ANG (DEG) -35.34 -153.68 87.31 134.14 123.30

A B C SV MAG (KV) 41.222 40.328 40.812 40.583

V ANG (DEG) 0.00 -119.97 117.52 -0.57

A B C 3P

MW 2.607 2.514 2.769 7.890

MVAR 1.849 1.677 1.612 5.138

PF 0.816 0.832 0.864 0.838

LAG LAG LAG LAG

I1 3I2 3I0 V1 V2 3V0

MAG 76.978 6.342 0.424 40.779 0.334 2.551ANG (DEG) -33.90 -105.67 123.30 -0.82 150.90 29.60

FREQ (Hz) 59.92 VDC (V) 114.8

IA IB IC IN IG 3I2

DEMAND 77.5 74.6 78.4 0.4 0.4 6.7

PEAK 146.4 133.7 150.0 35.2 35.3 35.3

MWA MWB MWC MW3P MVARA MVARB MVARC MVAR3P

DEMAND IN 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

PEAK IN 0.2 0.2 0.4 0.6 0.2 0.2 1.2 1.2

DEMAND OUT 2.6 2.5 2.8 7.9 1.8 1.7 1.6 5.1

PEAK OUT 4.6 4.3 5.2 14.1 3.8 3.2 3.1 10.1

MWhA MWhB MWhC MWh3P MVARhA MVARhB MVARhC MVARh3P

IN 0.2 0.2 0.2 0.5 1.0 1.1 1.2 3.3

OUT 28278.4 26797.4 31523.3 86599.1 21038.4 17781.7 17006.4 55826.5




3.8 Provide useful supervision

� PT voltage memory polarization unit secures reliableoperation of relay employed on short line while a three-phase

fault occurs close to busbar .

b. Directional elements with V2 and V0 voltage polarization

units secure reliability and selectivity of relay under earth

fault condition.




3.8 Provide useful supervision (continued)

c. AC under- and over-voltage;

d. 69kV PT phase-loss supervision;

e. 69kV line phase-loss supervision;

f . Over-/under-frequency;

g. DC over-/under-voltage;

h. DC source loss;

i. Circuit breaker operating and wearing status;

g. Fault location indication;

k . Relay fault alarm.




3.9 other advantages of 351 Digital Relay

3.9.1 Two-level access-in password

� First-level available for protection technicians to routinely inspect and

review.� Second-level available for protection Engineer/senior technicians to

program relays and operate circuit-breakers.

3.9.2 others

� flexible-to-program

� easy-to-install-and-test

� free-to-maintain

� small-in-size

� sealed in metal box to prevent radio interference and climate affection

� work under temperature range of ±40--+85°C



4. 2030 Communication Relay & Software

A. Configuration

� Being called as Master relay for substation communication and integration;� Seventeen(17) 9-pin communication ports;

� Programmable relay

B. Feature

� Data information collection, storage and distribution

� Remote or local control, metering and monitoring

� Event alarming/ paging

� Time and date synchronization

4.1 2030 Configuration & Feature




4.2 Workstation

2030 communication relay

587351 551 321 DFP-100

LOCAL

PC

MODEM

MODEM

TELEPHO NE BOARD

WORKSTATION

REMOTE PC

(5040)

PHONE

(PAGING)

MODEM2030

MODEM2030

MODEM2030

MODEM2030

Figure 13 communication configuration




4.3.1 Human machine interface (HMI)

Hyper Terminal is a widely used software for either local or remote relay communication

4.3.2 5010 Setting assistance software

The most complex work on 351 relay is programming due to 512settings in one of six groups.

This software can:� make relay programming facilitated;

� synchronize date and time on relays.

4.3 Communication software




4.3.3 5040 Power system report manager

5040 software was designed for establishment of Workstation.

It can:

� periodically or automatically retrieve the latest event reports from

designated digital relays;

� save event reports in database of workstation for viewing in

oscillography.

4.3 Communication software (continued)



5. A Captured Event

GG GG GGG

Friar¶s Hill

Cassada

Crabbs

LavingtonSwetesBelmontUnion Road

13 2

1311

456

78 9 12 1415

10

Figure 14 fault current distribution situation on May 05,2002

16

I NF=701A

IAF=552A

IAF=699A

IAS=675A 0S

I NF=700A

I NS=531A 0S

IAF=1642A

IAS=378A 0.5S

I NF=1589A

I NS=450A 0.5S

IAF=1911A

IAS=1407A 0S

I NF=2054AI NS=2016A 0S

IA(1.0)

L=1.62KM

1

Y/ Yo Yo/YYo/YY/ Yo

Y/ Yo Y/ Yo Y/ Yo Y/ Yo



5. A Captured Event( continued)

CRA-LAV

# DATE TIME EVENT LOCAT CURR FREQ GRP SHOT TAR GETS

4 05/05/02 06:21:26.909 AG T 1.62 1911 60.06 1 0 INST 50

42 05/05/02 06:21:26.901 67N4 Asserted

41 05/05/02 06:21:26.905 67N3 Asserted

40 05/05/02 06:21:26.905 67P3 Asserted39 05/05/02 06:21:26.909 67N2 Asserted

38 05/05/02 06:21:26.909 67P2 Asserted

37 05/05/02 06:21:26.917 67N1 Asserted

36 05/05/02 06:21:26.917 67P1 Asserted

35 05/05/02 06:21:26.917 67N1T Asserted

34 05/05/02 06:21:26.917 67P1T Asserted33 05/05/02 06:21:26.917 TRIP Asserted

32 05/05/02 06:21:26.917 OUT202 Asserted

31 05/05/02 06:21:26.917 OUT201 Asserted

26 05/05/02 06:21:26.963 IN101 Deasserted

21 05/05/02 06:21:26.972 52A Deasserted



5. A Captured Event( continued)

LAV-CRA

4 05/05/02 06:21:46.408 AG T 5.71 699 60.07 1 0 INST 50

40 05/05/02 06:21:46.404 67N3 Asserted

39 05/05/02 06:21:46.404 67N2 Asserted38 05/05/02 06:21:46.404 67P3 Asserted

37 05/05/02 06:21:46.413 67N1 Asserted

36 05/05/02 06:21:46.413 67N1T Asserted

34 05/05/02 06:21:46.413 TRIP Asserted

33 05/05/02 06:21:46.413 OUT201 Asserted

32 05/05/02 06:21:46.421 67P1 Asserted

31 05/05/02 06:21:46.421 67P1T Asserted

20 05/05/02 06:21:46.454 IN101 Deasserted

17 05/05/02 06:21:46.463 52A Deasserted



6. Conclusion

1. About two year operating experience shows that:

a. the digital relay protections secure 69kV transmission lines

and 11kV primary feeders operating under safe, reliablecondition;

b. the micro-processed directional over-current protection can be applied to the close-ring transmission network,

especially, to the short lines connected to small power system.



6. Conclusion

2. The established workstation makes daily inspection of relays and fault analysis easier.

� All event reports recorded in related relays can beimmediately downloaded by 5040 software within fewminutes once an event occurs.

� In accordance with the event reports listed in table, the

event sequence and cause, conclusion can be easilyobtained to guide system improvement.



6. Conclusion

3. Based on application of 2030 communication relays

and 5040 and other related software, the establishedworkstation performs functions as mini-SCADA

system on protection, monitoring, metering and

control.

Application of Digital Relay Protection on APUA.....

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