MINUTES OF THE 95th PROTECTION COMMITTEE MEETING … · MINUTES OF THE 95th PROTECTION COMMITTEE...

MINUTES OF THE 95th PROTECTION COMMITTEE MEETING

The 95th Protection Committee Meeting was held on 3rd & 4th January 2007 at Tarapur.

The list of participants is placed at Annex -I.

At the outset, Shri O.P Goyal, Site Director, NPCIL, Tarapur welcomed the members and

participants to 95th Protection Committee Meeting. He said that it was a great pleasure for

Nuclear Power Corporation of India Limited in holding this 95th WRPC PCM at Tarapur

and thanked WRPC for giving an opportunity to host the Protection Committee Meeting by

Tarapur Atomic Power Station –3 & 4. Welcoming Shri Patel, Member Secretary WRPC

and members & participants to 95th Protection Committee Meeting, Shri Goyal expressed

that the discussions during the 95th Protection Committee Meeting would give fruitful

results and the Protection Engineers of the constituents of WRPC would share their

experiences and implement the decisions/recommendations of the Protection Committee to

improve the overall performance of the Western Grid. He stated that TAPS-1&2 is the first

Nuclear Power Plant in the country installed in 1969 and TAPS-3&4 is India’s first

2x540MW Nuclear Power Plant.

Shri P. Patel, Member Secretary, WRPC welcomed all the participants to the 95th

Protection Committee Meeting. He thanked NPCIL for having consented to host the

meeting at TAPS- 3 & 4 and for the excellent arrangements made for the meeting and

comfortable stay of participants. He expressed special thanks to Shri Goyal and other

senior officers of NPCIL for attending the meeting in spite of their busy schedule. He

stated in the last three four years, no major grid disturbance had occurred in Western

Regional grid, which is at present operating in synchronous mode since 26th August 2006

with Eastern, North Eastern and Northern regional grids covering around 80% of the

country for last four months. It has been observed that with the increased system size,

Power Number of the combined grid has increased to the order of 1800MW thereby

reducing fluctuations in system frequency. However, average operating frequency has

come down. He indicated that Protection Committee Meeting is a gathered team of experts

from various utilities in the field to evolve solutions to problems in the area of protection

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and provides platform for exchange of technical information for safe and secure operation

of the regional grid. He requested protection engineers to keep operational all protection

schemes including Under Frequency Relays. He emphasized on monitoring of operation of

these relays, load relief obtained and expected for safe & secured operation of the enlarged

grid.

He informed the participants that a presentation by Shri Dhananjay Sambhare of M/s

AREVA on SCADA and Automation of Sub-Station is arranged on 4th January 2007. He

then requested Shri S. D.Taksande, Superintending Engineer (Protection), WRPC, to take

up Agenda items for discussion.

Shri S. D.Taksande, Superintending Engineer (Protection), WRPC, welcomed all the

members and invitees to the 95th Protection Committee Meeting. He informed the

participants that WRPC PCM Agenda & Minutes are made available on WRPC website

(www.wrpc.nic.in). The agenda items were taken up for discussion in seriatim.

Item No.1: Confirmation of Minutes of 94th Protection Committee Meeting.

Minutes of 94th Protection Committee Meeting of WRPC held on 21st & 22nd September

2006 at Aurangabad in Maharashtra were circulated vide WRPC letter no. Prot./94-

PCM/2006-07/WRPC/7421 dated 17th October, 2006. No comments were received from

any of the members.

The minutes for 94th Protection Committee Meeting were confirmed.

Item No.2: System disturbances

2.01: System disturbance at 220 kV Zagadia S/S in GETCO system on 04-07-2006

The representative of GETCO explained that on 04.07.2006 at 12:45Hrs, flash was

observed in the switchyard between bays of 50MVA, 220/66kV transformer No. 2 & Bus

Coupler and simultaneously Zone- A bus bar protection relay type RADSS operated

resulting in tripping of all the bays connected to Bus-A.which includes 220kV Zagadia –

Mangrol # 1, 220kV Zagadia – Vav and 50MVA, 220/66kV transformer No. 2 and the bus

coupler. tripped. Tripping of all the breakers connected to Bus-A isolated the fault and Bus

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B remained in service. There was heavy rain with lightning and thunderstorm at the time of

occurrence and it is presumed that lightning might have struck causing flash over from R-

ph to ground of the Bus-A.

All tripped feeders and transformers were restored between 14:20Hrs and 14:30Hrs on the

same day.

Committee opined that though bus bar protection operated correctly, it seems that there were some unprotected zones against lightening The committee recommended the lightening protection arrangements of the sub station should be reviewed and necessary action need be taken for unprotected zones.

2.02: System disturbance at 220 kV Uran GTPS in MSETCL system on 11-07-2006

The representative of MSETCL explained that on 11.07.2006 two occurrences at 220kV

Uran GTPS took place one after the other.

Bus section II occurrence:

At 21:03Hrs, 10MVA, 220/6.6kV station transformer no. II connected to 220kV Main

Bus –II at GTPS Uran tripped on relay indication of ‘Instantaneous O/C protection –

HV high set’. Generator Unit no. 8 and Generator Unit ‘Bo’ connected to Main Bus –II

tripped due to loss of Station supply, which caused reverse power flow condition.

However, 220kV feeders & 220/22kV 25MVA transformer no. I remained in service.

Bus section I occurrence:

At 21:09Hrs, 10MVA, 220/6.6kV station transformer no. I connected to 220kV Main Bus

–I at GTPS Uran tripped due to bursting of its B-ph HV LA. At the same time B-ph of

220kV BHEL MOCB pole and its grading capacitor also burst. The un-cleared fault

resulted in operation of bus bar protection of bus section I. This resulted in tripping of all

elements connected to bus –I including bus coupler.

All tripped feeders, generators and station transformer no. II were restored between

21:40Hrs of 11.07.06 and 00:45Hrs of 12.07.06. The 10MVA, 220/6.6kV station

transformer no. I was charged through TBC on 12.07.06 at 19:30Hrs after replacement of

B-ph LA and breaker pole. Old Siemen make transformer differential relay type 7UT22

replaced by new Siemen’s relay.

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Committee opined that exact reason for tripping of 10MVA, 220/6.6kV station transformer no. II connected to 220kV Main Bus –II on ‘Instantaneous O/C protection – HV high set’ could not be ascertained. Committee suggested for checking the transformer over current – HV high set value for relay setting as per recommendations of WRPC relay co-ordination manual. MSETCL informed that they have already changed the high set value to 1.8x5 i.e. ‘9’ and subsequent to that there is no tripping.

2.03: System disturbance at 220 kV Achhalia S/S in GETCO system on 14-07-2006

The representative of GETCO explained that on 14.07.06 at 05:45Hrs, B-ph string of

220kV Achhaliya – Ukai (TH) –2 line flashed over at location no. 129, about 45kMs

from Achhaliya S/S. The line was connected to Bus-B at Achalia. While clearing the

fault, B phase pole of circuit breaker of 220kV Achhaliya – Ukai (TH) –2 line failed,

breaker got stuck up and all the circuit breakers connected to 220kV Bus A & B at

Achhaliya tripped. The circuit breaker of 220kV Achhaliya – Ukai (TH) –2 line was

found in closed condition as it might have locked due to loss of SF6 gas in ‘B’ phase

even though operation of all the protection relays of the line. As LBB protection is not

provided at Achhalia S/S since commissioning long back, the fault could not be isolated

by tripping of all the feeders connected to bus no. 2. Fault continued to be fed through

other lines between Achalia and Ukai (Th), Ukai (Hy) and Jambua. Due to very high fault

current, the CTs of 220kV Achhaliya – Ukai (TH) –2 line breaker & BC breaker might

have partially saturated and the difference in current might have extended operating

voltage to Bus bar supervision relays 95AX, 95BX & 95CHX relays which operate at a

set voltage of 12Volt after a built in timer of 3 seconds. The Directional Back-up relays

of 220kV Achhaliya – Ukai (Hy-1), 220kV Achhaliya – Jambua 3&4, 132kV GNFC 1&2

operated. 220kV Mota – Ukai and Vav-KAPP line 1&2 also tripped on Directional E/F

relay. Simultaneously all the generating units of Ukai power station tripped and there was

no generation at Ukai power station. As 220kV Achhaliya – Ukai (TH) –1 line did not

trip, the fault continued to be fed through 220kV Vav-Ukai line. As the generation of

Ukai power station became zero, the fault current should have diminished to a very low

level. Thus high resistive fault was being fed from far away substations.

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The system was made normal by charging 220kV Bus A through Jambua line 3. Then

Bus B was charged through Bus Coupler and all 220kV feeders & 220/132kV

transformers were immediately taken in to service between 06:10Hrs & 08:00Hrs of

14.07.06. 220/66kV transformer no. 4 was taken in service at 11:12Hrs of 14.07.06.

220kV Jambua ckt 1 & 2 kept OFF.

Committee opined that as there was no L.B.B. protection scheme provided at 220kV Achalia S/S therefore fault continued to be fed for longer time. CAG Bus bar protection did not operate as it has tendency of not to operate on high resistive type of fault. Committee therefore suggested that CAG Bus bar scheme may be replaced with Numerical Scheme. GETCO informed that L.B.B. scheme is being provided shortly on 220kV Achalia S/S.

2.04: System disturbance at 220 kV Ranasan S/S in GETCO system on 22-07-2006

The representative of GETCO explained that on 22.07.2006 at 14:10Hrs, all the feeders

and transformers including Bus Coupler connected to Bus–I tripped on 96 relay without

operation of Bus Differential relay. There was no operation of LBB on any feeder,

transformer or bus coupler. Non-operation of LBB was attributed to insulation damage of

two wires and touching the base panel of relay panel in PGCIL line no. 1.

All tripped elements restored between 14:50Hrs and 15:27Hrs.

Committee observed that non-operation of LBB scheme was due to insulation damage of two wires in relay panel in PGCIL line no. 1. Committee, therefore, suggested for proper care such as rodent control, routine observations to avoid such occurrences in future.

2.05: System disturbance at 220 kV Kim S/S in GETCO system on 31-07-2006

The representative of GETCO explained that on 31.07.2006 at 01:45Hrs, 220kV Y-phase

jumper (dropper) of bus B isolator of 220kV Kim – Utran ckt # 2 detached from bus B

and earthed. Both 220kV Kim- Utran line 1 & 2 tripped at Utran end on operation of U/F

relay for Utran #1 and distance protection relay (B-ph zone-2) & backup protection in

respect of Utran# 2. At Kim end 220kV Utran #1 tripped on back up protection and there

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was no tripping of 220kV Utran #2. However, the bus bar protection scheme (Make: U.E.

– VXL, Type: AHT – 1H) provided at the sub station had not operated. Utran generating

station is connected to grid only through 220kV Utran – Kim # 1 & 2. Since both the

220kV lines from Kim at Utran tripped, Utran station islanded. At Utran power station

under frequency relay operated and resulted in tripping of circuit breaker of 220kV Utran

– Kim # 1 at Utran end. 220kV Kim – Utran ckt # 2 also tripped only at Utran end. No

other line tripping occurred at that instance.

220kV Kim – Utran ckt # 1 restored at 07:05Hrs while other line 220kV Kim – Utran ckt

# 2 synchronised at 15:00hrs on the same day.

Committee observed that snapping of 220kV Y-phase jumper of bus B isolator of 220kV Kim – Utran ckt # 2 could have been avoided if regular checks like Thermovision/Inspection were carried out. Hence, regular scanning is required as the line tripped during normal loading condition. Committee opined that islanding at Utran is unintentional and took place due to tripping of lines, which could have been avoided by proper relay co-ordination. Relays are racing and hence time gradation is recommended. Also VXL Bus bar protection scheme did not operate which needs further

investigation.

2.06: System disturbance at 220 kV Karamsad S/S in GETCO system on 02-08-2006

The representative of GETCO explained that on 02.08.2006 at 15:45Hrs a monkey, while

jumping between Bus –B gantry and R – phase extension pipe of 220kV Bus –B, got

electrocuted and resulted in tripping of all elements connected to both the buses A & B.

The bus bar protection scheme RADSS (ABB make) provided at the S/S did not operate

at the time of occurrence. All feeders tripped from opposite end either on Zone-2 or non –

directional back up relay and transformers on E/F (HV, LV), Inter trip. Non-operation of

Bus Bar Protection scheme was attributed to loose connection in Bus-A – RD-3, Rd-11

resistance units.

All tripped elements were restored on the same day between 15:55Hrs and 16:25Hrs.

Committee observed that it was a case of mal operation of RADSS (ABB make) Bus

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bar protection scheme due to loose connection in Bus-A – RD-3, Rd-11 resistance units. GETCO informed that checking of all panels was carried out. Subsequently, no abnormality except the loose connection was observed. GETCO confirmed that they have done co-ordination of relays also.

2.07: System disturbance at 400 kV Waluj S/S in MSETCL system on 04-08-2006

The representative of MSETCL explained that on 04.08.2006 at 11:09Hrs, 400kV Bus

Bar protection scheme Bus –II (Zone-II) at Waluj receiving sub station operated tripping

all the elements connected to Main Bus –II including Bus Coupler. 400kV Bhusawal ckt.

& ICT-II also tripped simultaneously. No extra load shedding was taken for this

occurrence and S/S continued to feed its normal load of 250MW. The exact reason for

operation of bus bar protection could not be ascertained and matter being referred to M/s

ABB for their opinion and comments.

Committee opined that non-operation of ABB make Bus bar protection might be due to earth leakage near SR & DR contacts of RADSS scheme. Committee, therefore, suggested for quickly sorting out the earth leakage problem. In this connection Committee referred discussions during 94th PCM at Aurangabad and suggested for adopting non-disruptive methods for measuring earth leakages as suggested therein.

2.08: System disturbance at 400 kV Asoj S/S in GETCO system on 20-08-2006 ???

The representative of GETCO explained that on 20.08.2006 at 23:12Hrs, 400kV Asoj –

Chorania line was switched off from Chorania S/S due to high voltage. While switching

off the breaker of 400kV Asoj – Chorania line from Asoj end, all the feeders and other

equipments connected to Bus – A tripped on operation of Bus bar protection (EE make

PBDCB scheme). The reason for Bus bar protection operation was attributed to sparking

between ‘Y-ph’ pole condenser and ‘Y-ph’ PIR of breaker. At Asoj, 400kV Chorania line

breaker (Make: ABB, Type: EL (V) F SL6-2) was tested for its functions like Timing

Test, Contact Resistance Measurement, Grading Capacitor & PIR Measurement etc and

werefound in order.

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All tripped elements were restored between 00:27Hrs and 02:45Hrs of 21.08.06 except

400kV Asoj – Chorania which was synchronized at 19:06Hrs of 22.08.06..

Committee observed that 400kV Indore – Asoj Ckt-1 is tripping i.e. AREVA make EPAC distance scheme is picking for close in reverse fault and tripping the feeder. Therefore, Committee suggested that in this case removal of reverse reach could be thought for Indore line in consultation with PGCIL OR Replacement of EPAC relay by numerical one is also recommended.

2.09: System disturbance at 220 kV Utran GBPS in GSECL system on 23-08-2006

The representative of GSECL explained that on 23-08-06 at 19.53 Hrs, while

synchronizing GT-1 “TC-1 and TC-2 unhealthy” facia appeared and the machine could

not be loaded because of which reverse power relay and trip relay 86U operated but GT

breaker did not trip. Hence, Bus bar protection operated through LBB Protection relay,

resulting into tripping of STG, Kim-1, ICT-1 connected to Bus-B and Bus coupler

through bus bar trip relay – 96.

The islanding scheme operated due to above tripping, which caused tripping of GT-3,

132 KV Kim-2 connected to Bus-A and 66 KV SECo feeders G-1 and G-2.The GT-2 also

tripped due to increase in exhaust temperature of Gas Turbine.

On detailed checking, the fuse of DC supply of trip control circuit was found blown

resulting into lock out of breaker trip circuit.

The station supply was restored through 66 KV Vav feeder with the help of 10 MVA

transformer and all equipments were taken into service between 20:50Hrs and 22:44Hrs

on the same day except GT-1 & GT-2 which were synchronized on 24.08.06 at 23:00Hrs

& 10:58Hrs respectively.

Committee opined that D.C. fuse blow up while closing the generator breaker might be due to inadvertant D.C. shorting. Committee recommended that both trip ckt coils should have independent D.C. supply which was not there during this occurrence. GSECL agreed to these modifications.

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2.10: System disturbance at 220 kV Karamsad S/S in GETCO system on 30-08-2006

The representative of GETCO explained that on 30.08.2006 at 04:01Hrs, R phase

insulator string of 220kV Karamsad – Asoj # 1 flashed over at location no. 15 and earth

wire (E/W) broke between location nos. 14 & 16 from Karamsad end. As such 220kV

Karamsad – Asoj # 1 tripped from both ends but at Karamsad end, R phase pole got stuck

up and failed to open. As the fault was not cleared, LBB protection operated and resulted

in tripping of all the feeders connected to Bus A & the Bus Coupler.

All tripped feeders including bus coupler were restored on the same day between

04:40Hrs and 04:53Hrs.

Committee opined that L.B.B. protection operated correctly for stuck-up breaker at Karamsad. However, matter of stuck-up breaker needs to be investigated further. GETCO agreed to do so.

2.11: System disturbance at 220 kV Uran GTPS in MSETCL system on 09-09-2006

The representative of MSETCL explained that on 09.09.2006 at 21:15 Hrs, 220kV B

phase C.T. (1985 make) of generating unit no. 6 burst and caught fire resulting in tripping

of unit no. 6. Simultaneously, 25 MVA, 220/22 kV transformers –I&II also tripped. No

other element i.e. line / transformer or generator unit was tripped, however, many

equipments pertaining to generating unit no. 6 got damaged. The cable connecting LV

bus to NGT in respect of 25 MVA 220/22 kV transformers no. I was found punctured and

got damaged, the same was replaced on 10.09.06 at 00:20Hrs. Oil leakage in B phase

NGT C.T. of 25 MVA 220/22 kV transformers no. II was observed and bottom portion

buckled. Hence after repairs / replacement / testing of B phase NGT C.T., 25 MVA

220/22 kV transformers no. II was recharged on 18.09.06 at 00:03Hrs and loaded on the

same day at 16:11Hrs. The oil leakage in 220kV R – ph breaker pole in respect of

Generator unit no. 5 was observed but this unit was in service up to 12:30Hrs on 12.09.06

till the unit was hand tripped.

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The generator unit no. 6 was taken in service on 14.09.06 at 12:00Hrs after replacement

of 220kV Y & B phase CTs, 220kV R & B phase PTs, Y phase MOCB pole, post

insulator of Q9 B-ph isolator and post insulator of Q7 B-ph TBC isolator.

Committee opined that bursting of ‘B’ phase CT might have generated zero sequence current which found nearest path through HV ‘B’ phase winding of 25 MVA 220/22 kV transformers no. II and transformer tripped on differential protection. Bus bar protection did not operate as fault being cleared by GT breaker. MSETCL agreed that this could be the probable reason as differential protection scheme was checked and no abnormality was observed.

2.12: System disturbance at 132kV Dhuvaran TPS in GSECL system on 20-09-2006

The representative of GSECL explained that on 20-09-06 at 18.10 hrs, 132 KV

Dhuvaran-Dhandhuka line no.2 was charged after shutdown. At 18.14 hrs the R-phase

jumper from line isolator to wave trap snapped from wave trap end and fell on fence. At

the same time R-phase jumper from bus isolator to breaker also snapped from breaker

end and grounded through the structure of bus isolator and bus bar differential

protection operated resulting into tripping of all elements i.e. generators, transformers,

feeders connected to Bus Zone – I including Bus Section Breaker.

Generator – 5 connected to Bus Zone-II was tripped manually due to unavailability of

station auxiliary supply which was fed from SST-1 and SST-2 connected to Bus Zone-I,

as SST – 3 transformer was under shutdown for replacement of old circuit breaker and

current transformer.

After isolating 132 KV Dhuvaran – Dhandhuka line no.2, the Bus Section breaker

closed at 19.20 hrs and Bus – I was charged. All equipments were taken into service

between 18:30Hrs and 19:50Hrs on the same day except Generator-4 & Generator-5

which were synchronized on 21.09.06 at 06:37Hrs & 04:0Hrs respectively. Committee observed that there were two contingencies on that particular day i.e. REL 511 relay on 132 KV Dhuvaran-Dhandhuka line no.2 was taken out for

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maintenance due to which there was delay in clearance of fault and R-ph jumper from bus isolator to breaker also snapped causing operation of bus bar protection. Secondly SST-3 transformer was out due to which Generator Unit # 5 was tripped manually as station auxiliary supply was fed from SST-1 and SST-2 connected to Bus-1. Committee opined that bus bar protection operated correctly.

2.13: System Disturbance at TAPS 3&4 in NPCIL on 01-10-2006

The representative of NPCIL explained that on 1-10-2006 at 22.23.31.500, 400 kV

Tarapur- Padghe-II tripped on directional earth fault with C-phase to ground fault

indication and disturbance recorder data showing an earth fault current of 500A (Relay

setting 200A-1sec time delay) maximum varying from a value of 152A to 500A in

around 5seconds. The fault resistance was so high that the distance protection at

local/remote end could not detect a fault and TAPS-3&4 Main-II relay tripped on

directional earth fault (backup protection). Exactly one sec after this incident i.e. at

22:23:32:500 400 kV Tarapur-Padghe ckt-I tripped on zone-3 with a DTF of 192.7kM.

Around 1.4 sec after that 400 kV Padghe ckt –II remote end tripped on zone-II with a

DTF of 92kM. The C phase voltage dipped to 54.3kV ie the fault resistance reduced to

drastically but due to absence of permissive signal the relay tripped after Zone-2 time.

It was felt that the fault existed on 400kV Tarapur-Padghe ckt-II very near to the TAPS

3&4 Switchyard but nothing abnormal was found even after thorough yard survey. It was

during night with heavy rains and so it was concluded that an arcing discharge had

occurred in the line at that time which was transient in nature.

The fault in the 400 kV Tarapur- Padghe-II line could not be cleared until it transformed

into a low resistance fault. The non-operation of main/backup protection at remote end of

400 kV Tarapur- Padghe-II led to unwarranted outage of 400 kV Tarapur- Padghe-I.

Committee observed that relay co-ordination has to be achieved at both Tarapur and Padghe. Committee discussed at length all the aspects of relay co-ordination and concluded that some more inputs and deliberations are required, therefore, it was suggested that MSETCL, GETCO and TAPS-3&4 would sit together and mutually decide the relay settings. All the three utilities agreed to sort out the problem within shortest time.

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2.14: System Disturbance at 220 kV S/S Eklahare in MSETCL on 14-08-06

The representative of MSETCL explained that on 14-08-06 at0725 Hrs, 220 kV side B ph

C.T of Generating transformer of unit No.1 burst. This resulted in operation of 220 kV

Bus bar Protection scheme (RADSS) to operate. All 220 kV lines / equipments connected

to 220 kV Bus at OCR Eklahre sub Station including Bus sectionalizer-I at GCR Eklahre

tripped. The 220kV Eklahare- Bableshshwar ckt-I &II Carrier Blocking Scheme was

taken into service on 17.07.2006. At the time of occurrence of CT bursting, Blocking

command was not sent from Eklahare to Bableshwar sub station for 220kV Bableshshwar

ckt-I &II, causing tripping of 220 kV Eklahare- Bableshshwar ckt-I &II at Bableshwar

end on distance protection.

All equipments, units and lines were restored between 08:28 Hrs of 14.08.06 and 0640

Hrs of 15-08-06.

Committee observed that bus bar protection operated correctly for B-ph CT bursting of G.T. of unit no. 1. Committee also opined that in this particular case Carrier Blocking Scheme on 220kV Eklahre – Bableshwar ckt – I & II may be bypassed and replaced with Inter Trip Scheme on these lines. 2.15: System Disturbance at 220 kV S/S Itarsi in MPPTCL on 12-07-2006 The representative of MPPTCL explained that on 12.07.06 at 10:25Hrs, for attending the

hot points in 220 KV Sarni-IV bay at 220 KV S/S Itarsi, the load of 220kV Itarsi – Sarni

circuit IV was transferred to the Transfer Bay. After transferring the load, within

about 4-5 seconds of opening of the 220kV Isolator of 220kV Main bus-II, its ‘B’

phase Polycon Insulator towards the Bus, got broken from middle and hit the post

insulator structure, resulting in a Bus fault tripping all the feeders including Bus Coupler

connectecd to Bus-II.

Since the jumper of B phase Isolator connecting the Bus-2 and isolator was longest, a

post insulator was provided as support between isolator arm and the bus. After certain

moments, 4-5 seconds of opening the isolator the polycon insulator of C-phase got

broken from middle and hit the P.I. structure resulting in C phase earth fault. Since the

220 kV Sarni –IV feeder was on 220 kV Bus -2, feeders connected to this bus tripped

from other ends. The 160 MVA transformer of this bus also tripped on earth fault from

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132 kV side.

The 200 K.V. bus coupler connecting bus I & II tripped on earth fault separating both

buses. The 220 K.V Itarsi –Barwaha ckt. II and 220 kV Itarsi –Sarni ckt III and 3 x 40

MVA transformer remained charged on 220 kV Bus- I.

After the tripping of 160 MVA transformer, 110 MW load appeared on 3 x 40 M VA

transformer and 132 kV supply remained normal. To avoid the over loading of 3 x 40

MVA transformer, 132 kV Itarsi - Mandideep feeder and 132 K.V. Hoshangabad – Itarsi

feeder were opened at Itarsi end. Tripping of 220 Itarsi-Barwaha ckt No 1 from both

ends resulted in interruption to 220 kV substations Handia that is tapped on this feeder.

The system was normalised between 10:25Hrs to 10.55 Hrs on the same day.

Committee observed that bus bar protection at Itarsi operated correctly, however, Distance Relay at Sarni for 220kV Itarsi – Sarni ckt IV requires to be investigated further. 2.16: System Disturbance at 220 kV S/S Barwaha in MPPTCL on 18-07-2006

The representative of MPPTCL explained that on 18.07.2006 at 05:01 Hrs 220 kV

Khandwa Barwaha line first tripped from both ends. There was persisting fault on 220kV

Barwaha-Khandwa line, which was first cleared from both the ends. It was switched on at

Barwaha end but due to blowing of its D.C. fuse in the trip circuit, it did not trip. It

resulted into prolonged fault feeding and delayed tripping from all other connecting

feeders.

The 220 kV Khandwa Barwaha line first tripped from both ends at 05.01 Hrs on

18.07.06. It was due to a fault on tower No. 156 where the earth wire was found broken

and disc of R- phase totally flashed over and the conductor was resting on Y – phase

cross arm. The tower is located in rocky strata and offered high resistance to fault.

Under the prevailing conditions there was persistent fault on the line and when the 220

kV Khandwa line from Barwaha substation was closed at 05:25 Hrs, the breaker got

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closed, but due to blowing of D.C. fuse the breaker did not trip even after the correct

operation of the E/F Relays, which subsequently got burnt. The DPR did not operate, as

the D.C. was not available.

Hence the tripping from Indore and khandwa substation took place, which is in order.

However, the high resistance fault current kept continuously passing on 220 kV

Khandwa- Barwaha line, this has caused R- phase voltage drop initiating the CVT alarm

on 220 kV Itarsi- I feeder. But the fault being a high resistance fault, the DPRs at Itarsi

220 kV S/S could not sense it.

This also caused unbalance currents on 132kV radial feeders viz. 132kV Choti-Khargone,

132kV Chhegaon & 132kV Sanawad, and caused their tripping on earth fault indications.

At 05:45Hrs, when the 132kV Chhegaon feeder was charged from 220 kV S/S Barwaha,

it appears, that all discs of 220kV Barwaha- Khandwa line, got flash over at tower

location No. 156 and R phase conductor fell on Y phase cross arm. This resulted in

sufficient fault current in R & Y phases, for DPRs at 220kV Itarsi to pick up, causing

tripping of 220kV Barwaha- Itarsi I & II feeders on R,Y, Zone - II.

After isolating the faulty line the rest of healthy lines were normalised between 06:10 to

06:20 Hrs.

The 220kV Barwaha- Khandwa line was charged on 20.07.06 at 20:34Hrs after

rectification of line fault.

Committee observed that D.C.leaage supervision should be carried out regularly for avoiding such kind of D.C. failures.

ITEM NO. 3: Tripping of lines / ICTs:

The incidences of tripping of lines and ICTs during the period 01-07-2006 to30-09-2006

were discussed during the meeting.

Observations of the committee are enclosed at Annex –3.

Minutes of 95th PCM

ITEM NO. 4: Information on A/R, DR and SER in Western Region:

PCM forum of WRPC is monitoring the progress and working conditions of A/R, DR &

SER at all 400kV locations and important 220kV generating & interstate locations where

the same are yet to be provided. In the 95th PCM constituents were specifically requested

to furnish the list of 400kV locations which do not have A/R, DR and SER provided in

their system. Also, constituents were requested to furnish any change in status already

furnished by constituents for reviewing by the committee.

GETCO representative informed that Numerical Relays with built in facility of DR are

provided at all 400kV lines in their system except for 400kV Asoj-Ukai & 400kV Asoj-

Wanakbori lines where it is under process. MPPTCL representative informed that in their

system also Numerical Differential and DPR are being provided on EHV lines.Other

constituents POWERGRID, MSETCL have A/R, D/R facilities in their system.

Committee once again emphasised that SERs and DRs along-with GPS time

synchronisation are essentially to be provided on priority at all 400kV S/Ss first and

then at all important 220kV S/Ss for proper analysis of the events during

disturbance and for taking required preventive measures.

ITEM NO.5: Synchronized operation of Northern and Central (WR-ER-NER) grids

and Under Frequency Relay (UFR) Settings

Member Secretary, WRPC informed the Committee that Northern and Central (WR-ER-

NER) Grids were synchronized on 26th August 2006 by commissioning 400kV

Muzaffarpur – Gorakhpur D/C line under Tala Transmission Project and the combined

grid is operating in synchronous mode since then. It has been observed that with the

increased system size, power number of the combined grid has increased to the order of

1800MW thereby reducing fluctuations in system frequency. However, average operating

frequency has come down.

He further stated that in the meeting taken by Chairperson and Member (GO&D) of

Minutes of 95th PCM

Central Electricity Authority it was recommended to raise settings of relays installed

under AUFL Scheme from 48.5Hz, 48.2Hz and 48.0Hz under 3 stages to 48.8Hz, 48.6Hz

and 48.2Hz respectively in both WR & NR. WR constituents have furnished details of

connected loads and confirmed having implemented the revised settings of Under

Frequency Relays installed under the scheme in their respective system. However, it was

reported by the Grid Operator that desired load relief was not obtained on a couple of

occasions when the frequency dipped to 48.8Hz. As such, all the WR constituents are

once again requested to re-check and confirm the settings of Under Frequency

Relays and connected loads.

The WRP Committee, in its second meeting, approved the revised settings of Frequency

Trend (df/dt) Relays for implementation in the Western Region as below:

Load shedding (MW) to be effected by

Setting

(Hz)/(Hz/sec)

Total Load

Relief in WR

(MW) GETCO MPPTCL MSETCL TPC CSEB

49.2/0.4 2472 1001 392 686 273 120

49.0/0.2 2212 1001 393 687 91 40

48.8/0.1 3023 1521 546 825 91 40

Total 7707 3523 1331 2198 455 200

The two stages of df/dt relays - 49.2Hz /0.4Hz per sec and 49.0Hz /0.2 Hz per sec are

already operational in Western Region. In view of the synchronized operation of NR–

WR–ER-NER systems and raising the setting of 1st stage UFRs to 48.8 Hz, it was

proposed to introduce a new setting of 48.8Hz /0.1 Hz per sec. This stage was initially

proposed for operation in Alarm Mode without connecting any load on this stage to know

the number of instances of operation. WRLDC had expressed that this third stage would

only come in picture when there would be a generation loss of more than 1000MW,

which is not very frequent. During the 368th OCCM of WRPC, the sub-committee had

observed that df/dt relays at 48.8Hz /0.1 Hz per sec, which were kept in Alarm Mode had

not operated even once during the one month period. Accordingly it was proposed to

make this stage operational. WRP Committee in its 2nd meeting requested WR

constituents to operationalise the relays with revised df/dt settings, which were

Minutes of 95th PCM

earlier, kept in the Alarm Mode.

Member Secretary, WRPC requested constituents to ensure implementation of both

the AUFL Schemes for safe and secured operation of combined grid in general &

WR grid in particular.He also requested for feeder wise information to be furnished

for proper monitoring of the scheme.

ITEM NO.6: Special Protection Scheme – Run back of generating stations

Member Secretary, WRPC informed the Committee that Northern and Central (WR-ER-

NER) Grids are operating in synchronous mode since 26th August 2006. It may be noted

when both 400kV Muzaffarpur – Gorakhpur lines are in service along with Tala HEP and

other additional generation in ER, then tripping of these lines might cause serious

overloading of lines in WR and thereby in-secured operation of WR necessitating for a

Special Protection Scheme.

NR and WR are receiving power from ER, since source of surplus generation is in ER.

As such, generation in ER is required to be reduced in the event of tripping of any of ER–

NR or ER–WR AC links to restrict the overloading and resultant disturbance in the

region. Accordingly, the following scheme was proposed and approved in the 2nd meeting

of WRP Committee held on 12th Oct.2006.

“Since NR & WR connected through ER, separation of regions can be

sensed through sudden frequency rise in ER. In order to control tie-line

flows from ER, it is essential to back-down generation automatically in

ER. Normally, the flows on ER-NR links will be to the tune of 1500MW on

an average and assuming the flows on ER-WR link is about 1500Mw and

further loading is to be avoided, then there will be a need to back-down

generation in ER generating stations by 1500MW to retain pre

occurrence conditions. ER has about 5 units of 500MW and considering

HP/LP bypass action, the load on 500MW units can be reduced by

1500MW as 60% of the steam is bypassed. The action can be triggered at

50.8 / 51.0 Hz. This would reduce / maintain the tie line flows to the

only region connected to ER”.

Minutes of 95th PCM

Member Secretary informed that the views of WRPC have been taken up with ERPC for

their consideration and implementation

Committee noted the above scheme proposed & approved by the WRP Committee.

Member Secretary, WRPC, requested constituents to think over and suggest for any

other alternative scheme in the matter which can be studied by committee

ITEM NO.7: Frequent tripping of 400kV SSP – Dhule lines at 400kV Dhule S/S

Member Secretary, WRPC stated that during 94th PCM, MSETCL have requested for

restoration of 2x80MVAR Line Reactors for 400kV Khandwa ckts # 1 & 2 at 400kV

Itarsi S/S in order to minimize O/V problem at 400kV Itarsi S/S, which is feeding S/S

for Dhule. Frequent tripping of 400kV SSP – Dhule lines on over-voltage is affecting

other 400kV lines at 400kV Dhule S/S and Western Grid as well. The issue of high

voltage during low load conditions in Western Maharashtra system was earlier

discussed in the 1st WRPC meeting held at Pune on 31st May 2006 wherein WRLDC

had suggested that the 80MVAR reactor at Itarsi, which is proposed to be removed by

POWERGRID for shifting it to the other location i.e. 400kV Seoni - Khandwa for Sipat

transmission project, should not be removed till reactors are provided at Khandwa and

Dhule.

Member Secretary, WRPC informed the Committee that the matter was again discussed

in the 2nd WRPC meeting held at Indore on 12th October 2006 wherein MPPTCL agreed

to provide 400/220 kV ICT at Itarsi to achieve higher fault level which would

eventually reduce the over voltage problem. Also, the problem of low voltage in the

corridor during Rabi season would be addressed by ensuring maximum availability of

MVAR by operating hydro generating units in synchronous condenser mode for

rendering MVAR support to the associated EHV grid to maintain voltage profile within

the permissible range. Testing and commissioning of facility for synchronous condenser

mode operation of RBPH units of SSP is under process.

Minutes of 95th PCM

In the WRPC meeting it was agreed that the shifting of existing reactor at 400kV

Itarsi S/S was essential for timely commissioning of 400kV Seoni – Khandwa line.

At the same time, need for a reactor of appropriate capacity at Itarsi was also

emphasized to avoid switching off the 400kV lines frequently under high voltage

conditions. As the procurement of a new reactor might take time, POWERGRID

were requested to try to locate a spare reactor for Itarsi.

Committee noted the observations of WRPC meeting.

ITEM NO.8: Follow up points:

8.1: A/R scheme of 400kV Tarapur – Boisar ckt. 1 & 2 and 400kV Tarapur –

Padghe ckt 1 & 2 at Tarapur NPCIL end

Presently the A/R selector switch of all the 400kV lines emanating from

TAPP 3 & 4 is kept in non-auto mode at TAPP end. NPCIL agrees in

principle to the view that single phase auto re-closure on all 400kV lines

should be commissioned to improve the transient stability of the regional

power system. At the same time, NPCIL is of the view that the prime mover

of the nuclear units vary in design from their counterparts of thermal

stations and the suitability of the prime mover at the generating station

needs to be ascertained before provision of auto re-closure feature on the

lines emanating from Nuclear Power Station. Accordingly, NPCIL have

referred to manufacture BHEL for indicating the suitability of the prime

mover for the auto re-closure duty.

NPCIL informed that so far they have not received any reply from the

manufacturer and after hearing from the manufacturer action based on the

recommendation of the manufacturer would be taken in the matter.

Member Secretary, WRPC advised NPCIL to expedite the feedback

from the manufacture, so that A/R scheme shall be put into service at

both ends for stability of system NPCIL representative agreed to

pursue the matter further with M/S BHEL

Minutes of 95th PCM

8.2: Commissioning of PLCC system in 220kV lines of other utilities

emanating from POWERGRID sub – stations

WRPC Protection Committee has agreed to follow CBI&P guidelines in the above

matter. As per CBI&P manual, there should be at least one carrier aided non-

switched three-zone distance protection scheme to protect 220kV line.

Accordingly, Committee has time and again emphasized the need for early

commissioning of PLCC panels and protection couplers wherever to be provided.

A: Raipur Sub-station:

Four nos. 220kV lines of CSEB are connected to Raipur S/S of

POWERGRID. These lines were commissioned in the year 1999-2000. The

PLCC panels were supplied and commissioned in stand alone mode since

commissioning of lines at Raipur S/S. CSEB was requested to expedite for

early commissioning of PLCC protection couplers at their end so that for all

these lines protection coupler can be used for inter tripping.

CSEB representative informed that commissioning of Protection

Couplers on three lines of CSEB connected to Raipur S/S was already

completed and the work for the remaining line 220kV Urla-Raipur

would be completed by the end of January, 2007.

B: Satna Sub-station:

Two nos. 220kV lines of MPPTCL are connected to Satna S/S of Powergrid.

These lines were commissioned in the year 1999-2000. The PLCC panels

were supplied and commissioned in stand alone mode since commissioning

of lines at Satna S/S. MPPTCL was requested to expedite for early

commissioning of PLCC protection couplers at their end so that for all these

lines protection coupler can be used for inter tripping.

MPPTCL representative informed that 220kV Katni – Satna line is

LILOed at PGCIL, Satna and converted to 220kV Katni – PGCIL # II

– Satna feeder. The carrier protection scheme has been commissioned

Minutes of 95th PCM

in 220kV Katni – PGCIL –I & II and 220kV Inter Connectors I & II

from PGCIL end as well as from 220kV Satna end. Thus the work is

complete as desired.

C. Khandwa Sub-station:

Four nos. 220kV lines of MPPTCL are connected to Khandwa S/S of

Powergrid. These lines were commissioned in the year 2005. The protection

coupler had not been procured at both ends, the same needs to be procured

and commissioned by MPPTCL at the earliest.

MPPTCL representative informed that Protection Couplers of 220kV

Nepa Ckts. 1 & 2 and that of 220 KV Julwania & Barwaha lines were

commissioned, however, relays are to be procured.

D. Boisar Sub-station:

Three nos. 220 KV lines of MSETCL are connected to Boisar S/S.

MSETCL have installed & commissioned only SPEECH panel on these

lines for communication purpose. MSETCL may expedite for procurement

and early commissioning of PLCC protection couplers at both ends so that

for all these lines protection coupler can be used for inter tripping mode.

MSETCL representative informed that protection couplers on 220kV

Boisar – Padghe have been commissioned on 07.12.2006.

8.3: Problem of PLCC in 400kV Korba-Raipur Ckt.# 2

The problem in one PLCC channel 200 Rx / 252 Tx KHz is still persisting

even after removing jumper at one location. The signal levels in other

PLCC channel 136/140 KHz has been found normal in ideal condition and

this signal levels getting disturbed during fault condition.

Minutes of 95th PCM

NTPC representative informed that the additional jump-ring still

existing would be removed within 15days to improve the performance.

8.4: Problems in newly commissioned GETCO bays at Dehgam SS:

400 KV Wanakbori – Soja line of GETCO was made LILO at

POWERGRID Dehgam SS in the month of March 2005. Since

commissioning, the following C&R problems are being encountered in

Soja & Wanakbori bays at Dehgam SS:

a. Disturbance Recorder and Event logger are not working for both lines.

b. For Soja line, during hand tripping of only main CB, direct trip signal

extended to remote end i.e. without tripping tie CB at Dehgam end For

Wanakbori line, during hand tripping of CB, direct trip signal not

extended to remote end i.e. PLCC inter trip command not connected in

case of hand tripping.

GETCO representative informed that the commissioning of Disturbance

Recorder and Event logger for both the lines (already installed) was

pending. The matter was taken up with M/s ABB but they failed to rectify

the problem. The equipments were procured from M/S ABB and supplied

through M/S Siemen. . GETCO would carry out the necessary changes in

association with POWERGRID Dehgam to resolve the problem.

Committee opined that during H/T of a short line of 40kM length,

extension of D/T signal to remote end need not be implemented.

8.5: Problem in Bhopal # 2 Main CB At ItarsI S/S:

At Itarsi S/S, main CB of 400 KV Itarsi – Bhopal # 2 was not in service

due to leakage of air from magnetic ventile from 16.06.06.

MPPTCL representative informed that spares were procured from M/s

ABB Vadodara and overhauling of 400kV ABB make CB, serial no.

Minutes of 95th PCM

IB108370 installed at Itarsi S/S (Powergrid) on Bhopal # 2 main CB,

was carried out in presence of ABB representative. The CB was taken

back in service on 13.11.2006 at 10:48 hrs.

8.6: Simultaneous tripping of 220 kV Kakrapar – Vav I & II on 14.07.06

Both 220 KV Kakrapar – VAV Ckt. 1 & 2 tripped simultaneously at

KAPP end only at 05:41 HRS on 14.07.06 for the fault in 220 KV

Kakrapar – Ukai line. POWERGRID raised this issue during 94th WRPC

PCM but as no representative from KAPS NPCIL attended the meeting,

the reasons for undesirable tripping of KAPP-VAV lines for the fault in

other line and the remedial measures to be taken could not be discussed.

The issue was deliberated in details and NPCIL representative informed

that the reasons for undesirable tripping of KAPP-VAV lines for the

fault in other line is due to improper relay co-ordination and the same

will be revised in consultation with GETCO/ PGCIL so as to avoid such

tripping in future.

8.7. Non – Auto -reclose of 400kV Indore – Asoj Ckt # 2 at Indore end

Frequent failure of A/R for the line at Indore end required thorough

examination by MPPTCL, so as to eliminate pressure switch problem in

order to achieve successful A/R for faults of transient nature in the trunk

line transmitting power to Gujarat state. MPPTCL representative in earlier

meeting informed that the CB A/R air pressure switch settings were

checked and found frequent drifting. The defective pressure switch was to

be arranged by PGCIL and the same required replacement on priority for

successful A/R operation. Committee during 94th PCM requested

MPPTCL and POWERGRID to examine jointly for taking required action

in the matter as 400kV Indore – Asoj ckt II is a vital link.

MPPTCL representative informed that they have given specific

requirements to PGCIL in the matter and for the same PGCIL have

Minutes of 95th PCM

placed order to M/s ABB. Thus within a month’s period work will be

completed.

8.8: Rectification of Bus Bar Protection Scheme at 400kV Nagda MPPTCL S/S

Bus Bar protection scheme, type SBNH 163 of EE make, at 400kV Nagda

S/S of MPPTCL is presently not in service. Four numbers new 400kV

PGCIL bays (Bina – Nagda – Dehgam) are likely to be commissioned in

the month of March 2007 at 400kV Nagda S/S. As such up-gradation of

Bus-bar protection scheme at 400kV Nagda S/S is essential for secured

grid operation.

MPPTCL representative informed that at 400kV Nagda S/S, Bus Bar

protection Scheme was commissioned in the year 1992 with a provision

of 4Nos. Bay. The protection scheme is lying defective since 04.05.1998.

He further informed that ED(T&C), MPPTCL, Jabalpur has taken up

the matter with CE (Planning), MPPTCL, Jabalpur for procurement of

new scheme suitable for 13No. feeders. 8.9: Mal-operation of AREVA make EPAC scheme on 400 kV Asoj-Indore line at Asoj

GETCO representative informed that on two occasions ie on 22-06-06 and

20-08-06 AREVA make EPAC scheme on 400 kV Asoj-Indore line- I at

Asoj end mal-operated on close in reverse faults.. The matter was

discussed in item no 2.08 and committee’s observation and

recommendation are given there in which may be referred

Committee requested POWERGRID to get in touch with GETCO for

sorting out the matter.

8.10: Non –auto reclosing of 400 kV Vindhyachal- Jabalpur lines.

POWERGRID informed that in case of B-phase to earth fault, the Auto

Re-closing of 400 kV Vindhyachal- Jabalpur Ckt- 3 & 4 is not taking

place at Vindhyachal, while the same is taking place at Jabalpur end in all

Minutes of 95th PCM

the incidences. The problem was suspected to be of CGL make breakers.

M/S CGL have suggested some modifications in the breaker which were

intimated to NTPC Vindhyachal. POWERGRID had carried out such

modifications at their end wherever CGL breakers are commissioned.

Committee suggested POWERGRID to supply material regarding

modifications to be carried out in CGL make breakers at their end

and correspond with VSTPS, NTPC for their comments.

8.11: Presentation on SCADA on Automation of Sub-station

A presentation by Shri Dhananjay Sambhare of M/s AREVA was arranged on 4th January

2007 on SCADA and Automation of Sub-Station. The presentation was well received and

appreciated by participants.

ITEM NO. 9: Date and Venue of the next meeting.

The next meeting is proposed during 4th/5th week of March 2007 wherein system

disturbances during the period 01-10-2006 to 31-12-2006 will be discussed. Exact date

and venue will be communicated separately.

Minutes of 95th PCM

ANNEX-I

LIST OF PARTICIPANTS

95th Protection Committee Meeting held on 3rd & 4th January, 2007 at

TAPS – 3&4, NPCIL, Tarapur (Maharashtra) CSEB ( Chhatisgarh State Electricity Board )

Shri P.M. Jog Superintending Engineer (Testing), Bhilai Shri Anil Dhar Addl. Superintending Engineer, Korba GETCO (Gujarat Energy Transmission Corporation Limited) Shri M.K. Mehta Superintending Engineer (Testing), Baroda GSECL (Gujarat State Electricity Corporation Limited)

Shri U.D. Adhvaryu Executive Engineer (Testing), Baroda MPPTCL (Madhya Pradesh Power Transmission Corporation Limited)

Shri V. K. Job Superintending Engineer (T&C), Bhopal Shri Shyamji Tiwari Superintending Engineer (LD), SLDC, Jabalpur MPPGCL (Madhya Pradesh Power Generation Corporation Limited)

Shri J. S. Grover Superintending Engineer (Th. Design), Jabalpur MSETCL (Maharashtra State Electricity Transmission Company Limited)

Shri R.N. Tonge Superintending Engineer (TCC), Vashi Shri B.T. Mahale Superintending Engineer (TCC), Nashik Shri N.D. Kudlikar Superintending Engineer (TCC), Aurangabad Shri B.H. Gujarathi Executive Engineer (LD), SLDC, Kalwa Shri P.S. Ingle Dy. Executive Engineer (TCC), Pune Shri D.Y. Chavan Dy. Executive Engineer (TCC), Nashik Shri R.D. Pedgaonkar Dy. Executive Engineer (TCC), Aurangabad Miss V.B. Sawant Jr. Engineer, (TCC), Vashi NTPC (National Thermal Power Corporation)

Minutes of 95th PCM

Shri T.K. Rao Dy. General Manager (EM), KSTPS, Korba NPCIL (Nuclear Power Corporation of India Limited) Shri K.P. Singh Addl. Chief Engineer(Trans.), H.Q., Mumbai Shri V.H. Manohar NPCIL, H.Q., Mumbai Shri N. Shankarnarayan NPCIL, H.Q., Mumbai Shri S.V. Shivalkar S.M.E.(E), TAPS 1 & 2, Tarapur Shri D.V. Kodge SO/C, TAPS 1 & 2, Tarapur Shri Mahesh P. Karia SO/C (EMU) TAPS 3 & 4, Tarapur PGCIL (Power Grid Corporation of India Limited)

Shri D. K. Javeri Manager, 400/220kV Betegaon S/S, Boisar Sachla Mishra Manager(OS), WRLDC, Mumbai TPC (Tata Power Company)

Shri Pravin Jain Assistant Manager (EQAG), Trombay, Mumbai TPL (Torrent Power Limited, former Ahmedabad Electric Company)

Shri A.B. Oza Manager (Elect.), Ahmedabad REL (Reliance Energy Limited)

Shri M. S. Bhadoria Manager (E/M), DTPS, Dahanu Shri A.M. Waknis Addl. Manager (Trans.), R/S Goregaon, Mumbai Shri S.S. Vaidhya Manager (E/M), DTPS, Dahanu WRPC (Western Regional Power Committee) Shri P. Patel Member Secretary Shri S. D. Taksande Superintending Engineer (P) Shri B. R. Joshi Executive Engineer (P)

Minutes of 95th PCM

ANNEXURE-3

TRIPPINGS OF LINES / ICTS

Sl. No.

NAME OF S/S

DATE OUT AT

NAME OF THE LINE/ICT

SYSTEM DATE/ CHARGED AT

REASON

3.01

400kV Asoj

03.07.06 17:01

400kV Asoj- Amreli

GETCO 20:00 A/T due to operation of Over Voltage stage-I protection at Asoj end.

3.02

400kV Raipur

03.07.06 17:58

400kV Sipat- Raipur

POWERGRID 19:55 Suspected problem in the station DC supply at NTPC Sipat end due to which line relays mal-operated for three ph. tripping of the line from Sipat end only.

3.03

400kV Kasor

04.07.06 02:08

400kV Kasor- Chornia

GETCO 05:20 A/T due to high system voltage.

3.04

220kV Haldarwa

04.07.06 19:50

220kV H’rwa- KAPP #1

POWERGRID/ GETCO

05.07.06 07:35

A/T on R ph to E/F in Zone-I at KAPP and on carrier added trip at Haldarwa. No cause found in patrolling of the line.

3.05

400kV Kasor

05.07.06 01:28

400kV Kasor- Chornia


3.06

400kV Kasor

05.07.06 05:38

400kV Kasor- SSP


3.07

400kV Asoj

05.07.06 05:38

400kV Asoj- SSP

GETCO 16:40 A/T due to operation of Main 1 & 2 protection at Asoj. O/V both stages-I&II prot.operated at Asoj end. Carrier sent to SSP end. No cause found in ground patrolling.

3.08

400kV Raipur

05.07.06 10:25

400kV Sipat- Raipur

POWERGRID 11:54 A/T on 3 ph fault at Sipat end only due to mal – operation of line protection at Sipat. Line remained charged from Raipur end.

3.09

220kV 10.07.06

220kV Kawas

POWERGRID/GETCO

11.07.06 A/T due to opening of Y-ph jumper towards Kawas end

Minutes of 95th PCM

9 Navasari

6 14:50

Kawas- Navasari

10:05 jumper towards Kawas end at Location No. 152(T).

3.10

400kV Itarsi – Khandwa #1

POWERGRID 20:11

3.11


POWERGRID 15.07.06 00.08

3.12

400kVKhandwa –Dhule #1

POWERGRID 20:16

3.13

400kV Khandwa

14.07.06 19:02


POWERGRID 20:19

All the 400kV lines connected to Khandwa S/S tripped on operation of Over Voltage stage-I protection at Kandwa S/S due to persisting over voltage in the system.

3.14

400kV Kasor

15.07.06 22:40

400kV Kasor- SSP

GETCO 16.07.06 14:40

A/T due to Y-ph disc insulator flashing over at Loc. No. 177.

3.15

220kV Navasari

16.07.06 01:00

220kV Nasik- Navasari

MSETCL /GETCO

19:30 A/T due to R-ph string flashing under Nasik jurisdiction at Location No. 155(S).

3.16

400kV Chornia

16.07.06 02:57

400kV Jetpur- Chornia

GETCO 13:33 A/T due to B-ph string flashed at Location No. 377(S).

3.17

400kV Vapi

16.07.06 04:54

400kV Jhanor- Vapi

POWERGRID 17.07.06 09:55

A/T due to flashover of Y phase insulator string at location no.72.

3.18

400kV Jetpur

17.07.06 02:58

400kV Amreli - Jetpur

GETCO 08:30 A/T on transient Y-ph to E/F.

3.19

400kV Chornia

17.07.06 03:20

400kV Jetpur- Chornia

GETCO 21:40 A/T due to B-ph string flashed at Location No. 330(S).

3.20

400kV Indore

17.07.06 06:14

400kV Indore- Asoj #2

POWERGRID 06:50 A/T on transient R ph to E/F. Line A/R at Asoj end only. A/R was unsuccessful at Indore due to CB air pressure low.

3.21

400kV Kasor

18.07.06 07:48

400kV Kasor- SSP

GETCO 20:38 A/T due to Y ph disc insulator at Location No. 177 flashed over.

3.22

400kV Nagda

18.07.06 07:58

400kV Nagda- SSP

MPPTCL 21.07.06 21:50

A/T due to middle phase all disc flash over & conductor falling on bottom cross arm at Loc. No.559.

3.22

400kV Indore

18.07.06

400kV Indore-

POWERGRID 20:30 A/T due to flashover of R phase insulator string at

Minutes of 95th PCM

09:18 Asoj #2 location no.674. 3.23

220kV TAPS

18.07.06 17:20

220kV TAPS- Bhilad

GETCO 19.07.06 12:34

A/T on Y-ph to E/F due to insulator flash over on Tower No.5. Earth Wire also found snapped off.

3.24

220kV KAPS

18.07.06 19:12

220kV KAPP- Vapi # 1

POWERGRID 19:39 A/T on transient A-ph to E/F.

3.25

400kV Bhilai

19.07.06 02:50

400kV Bhilai- Sarni

MPPTCL / CSEB

12:50 A/T due to operation of Over Voltage stage-I&II protection at Bhilai end. D/T signal received at Sarni end.

3.26


POWERGRID 07:36

3.27


POWERGRID 08.17

3.28


POWERGRID 07:43

3.29

400kV Khandwa

21.07.06 07:01


POWERGRID 08:40

All the 400kV lines connected to Khandwa S/S tripped on operation of Over Voltage stage-I protection at Kandwa S/S due to persisting over voltage in the system.

3.30

220kV TAPS

21.07.06 07:05

220kV TAPS- Bhilad

GETCO 08:35 A/T on trnsient R-ph to E/F.

3.31

400kV Kasor

22.07.06 01:05

400kV Kasor – Chorania

GETCO 01:31 A/T due to operation of Over Voltage stage-I&II protection at Kasor end. D/T signal received at Chorania end.

3.32


POWERGRID 09:04

3.33


POWERGRID 23.07.06 05.25

3.34

400kV Itarsi

22.07.06 07:35


POWERGRID 08:37

All the 400kV lines tripped on operation of Over Voltage stage-I protection at Kandwa S/S due to persisting over voltage in the system.

3.35

220kV Navasari

25.07.06 00:44

220kV Nasik – Navasari # 1

GETCO / MSETCL

17:55 A/T due to R ph LA burst and Transfer Bus PI damaged at Navasari yard.

3.36

220kV TAPS

26.07.06 12:08

220kV TAPS- Bhilad

GETCO 15:37 A/T on transient B-ph to E/F.

Minutes of 95th PCM

3.37

400kV Kasor

28.07.06 03:12

400kVKasor – SSP

GETCO 10:48 A/T due to operation of Over Voltage stage-I protection at SSP

3.38

400kV Kasor

28.07.06 03:12


GETCO 03:36 A/T due to operation of Over Voltage stage-I&II protection at Kasor end. D/T signal received at Chorania end.

3.39

400kV Kasor

28.07.06 03:38


GETCO 12:08 Line A/T due to high system voltage.

3.40

400kV Kasor

28.07.06 13:10



3.41

400kV Kasor

28.07.06 12:03

400kVKasor – SSP


3.42

400kV Padghe

28.07.06 13:01

400kV Tarapur- Padghe #1

POWERGRID 13:51 A/T due to operation of Over Voltage stage-I protection at Padghe end.

3.43

400kV Bhadravati

28.07.06 22:45

400kV B’vati- Chandrapur #4

POWERGRID 23:22 A/T at C’pur end only on D/T signal sent from B’vati due to suspected DC earth leakage at B’vati S/S. DC earth leakage in the scheme was identified and rectified at B’vati.

3.44

400kV Padghe

30.07.06 03:28


POWERGRID 13:51 A/T due to operation of Over Voltage stage-I protection at Padghe MSETCL end.

3.45

400kV Kasor

31.07.06 02:40

400kVKasor – Chorania

GETCO 03:00 Line A/T due to Y ph CVT fuse failed in M.K. box at Kasor end. Main-2 distance protection operated at Kasor and D/T signal received at Chorania.

3.46

400kV Khandwa

31.07.06 23:57


POWERGRID 01.08.06 06:33

A/T due to system O/V condition.

3.47

400kV Indore

01.08.06 17:07


POWERGRID 18:20 A/T due to operation of Over Voltage protection.

3.48

400kV Raipur

01.08.06 19:45

400kV Korba- Raipur #2

POWERGRID 21:22 A/T on transient R ph to E/F and line A/R successfully at Raipur end.

Minutes of 95th PCM

At Korba end, 3ph tripping took place.

3.49

400kV Kasor

02.08.06 22:20

400kV Kasor – GPEC

GETCO 22:20 A/T on transient B-ph to E/F. A/R successful at both ends.

3.50

400kV Raipur

05.08.06 17:58

400kV Rourkela -Raipur #1

POWERGRID A/T on D/T signal received at Raipur end due to mal-operation of PLCC system.

3.51

220kV TAPS

06.08.06 02:32

220kV TAPS- Vapi

GETCO 02:55 A/T on transient C-ph to E/F.

3.52

400kV Khandwa

06.08.06 05:36


POWERGRID 07.08.06 15:44

A/T due to operation of PRV of line reactor-1 at 400kV Dhule S/S.

3.53

400kV Bhadravati

06.08.06 17:21

400kV Raipur- B’vati #1

POWERGRID 18:30 Due to ingress of moisture, line reactor NGR-PRV protection at B’vati mal-operated. D/T signal received at Raipur end.

3.54

400kV Bhilai

08.08.06 10:25

400kV Bhilai- Korba(W)

CSEB 12:00 Main II operated at Bhilai end.

3.55

400kV Chandrapur

09.08.06 16:40

400kV C’pur- Parli # 1

MSETCL 12.08.06 13:50

A/T on B-N fault. Insulator string of B (RYB) ph found broken at Loc. no. 191 near Pandharkawada town.

3.56

400kV Chandrapur

09.08.06 22:38


MSETCL 09.04.06 23:40

Line A/T on O/V Stage-I at Parli end and L/O trip for remote fault at Chandrapur end on receipt of D/T signal.

3.57

deleted

3.58

400kV Raipur

15.08.06 13:44


POWERGRID 17.08.06 19:09

A/T due to operation of Over Voltage stage-I protection at Raipur S/S. D/T signal received at Korba end.

3.59

220kV KAPS

17.08.06 12:42


POWERGRID 13:26 A/T on transient C-ph to E/F.

3.60

220kV KAPS

21.08.06 10:04


POWERGRID 10:34 A/T on transient C-ph to E/F.

3.61

400kV Koradi

21.08.06

400kV Koradi-

MSETCL 23.08.06 09:48

Line A/T on Reactor B/U protection at Bhusawal end

Minutes of 95th PCM

22:10 Bhusawal # 1

and on L/O trip for remote fault at Koradi end. B ph CVT at Bhusawal became defective and the same was replaced.

3.62

400kV Boiser

22.08.06 03:42

400kV Boiser- Padghe

POWERGRID 05:26 A/T due to operation of Over Voltage stage-I protection at Padghe end. D/T signal received at Boiser end.

3.63

400kV Mapusa

26.08.06 00:13

400kV Kolhapur – Mapusa #1

POWERGRID 08:25 A/T due to operation of Over Voltage stage-I protection at Kolhapur MSETCL end. D/T signal received at Mapusa end.

3.64

400kV Kasor

24.08.06 09:08


GETCO 09:35 Line A/T at Kasor end only due to Y ph M-1 CVT fuse failed.

3.65

400kV Kasor

26.08.06 03:20



3.66

400kV Kasor

28.08.06 03:20



3.67

14:29

3.68

400kV Indore

31.08.06 13:51 15:27


POWERGRID

01.09.06 01:00

A/T due to operation of O/V protection at Indore due to problem suspected in Y phase CVT. Line restored after by passing Y ph CVT at Indore. Bus CVT Y ph voltage extended to meter and protection relays. CVT replaced.

3.69

400kV Jetpur

01.09.06 15:00

400kV Chornia – Jetpur GETCO 15:35 A/T at Chornia end only on

receipt of D/T signal from Jetpur end. B-ph HV LA of ICT No.2 at Jetpur end failed. Spurious carrier signal was generated at Jetpur end & the same was received at Chornia end.

3.70

400kV Mapusa

02.09.06 03:30

400kV Kolhapur -Mapusa # 1

POWERGRID 08:55 A/T due to operation of Over Voltage stage-I protection at Kolhapur

Minutes of 95th PCM

MSETCL end. D/T signal received at Mapusa end.

3.71

400kV Itarsi

07.09.06 11:41

400kV Jabalpur- Itarsi # 4

POWERGRID 14:10 A/T due to mal-operation of CSR protection at Itarsi end. D/T signal received at Jabalpur end.

3.72

400kV Chandrapur

10.09.06 15:40


MSETCL 11.09.06 12:18

Line A/T on R-B (RYB) ph to ph fault. Earth wire snapped at Loc No. 186.

3.73

400kV Padghe

11.09.06 13:36


POWERGRID 15:36 A/T due to B ph to E/F. Special patrolling carried but no fault was observed in the line. A/R selector switch kept in non-auto mode at both ends.

3.74

400kV Boiser

11.09.06 13:39


POWERGRID 15:08 A/T at Padghe end only due to mal-operation of relay.

3.75

220kV TAPS

13.09.06 15:33

220kV TAPS- Borivali

MSETCL 14.09.06 13:22

A/T on C-ph to E/F.

3.76

400kV Mapusa

13.09.06 17:01


POWERGRID 17:47 A/T due to operation of Over Voltage stage-I protection at Kolhapur MSETCL end. D/T signal received at Mapusa end.

3.77

220kV KAPS

13.09.06 18:07

220kV KAPP- Haldarwa # 2

POWERGRID 18:51 A/T on transient R-ph to E/F.

3.78

400kV Boiser

14.09.06 15:30


POWERGRID 16:17 A/T due to mal-operation of relay at Padghe MSETCL end.

3.79

400kV Raipur

14.09.06 15:33


POWERGRID 18:48 A/T due to R ph to E/F. A/R at Raipur end only. Afterwards operation of Over Voltage stage-I protection at Korba end resulted in three phase tripping.

3.80

400kV Nagda

14.09.06 15:46

400kV Nagda- Indore

MPPTCL 16:07 A/T due to operation of over voltage protection at Nagda.

3.81

400kV Padghe

15.09.06 18:31

400kV Tarapur- Padghe # 2

POWERGRID 19:38 A/T due to R ph to E/F. Line A/R at Padghe end only. A/R selector switch

Minutes of 95th PCM

kept in non-auto mode at TAPP end.

3.82

400kV Mapusa

16.09.06 17:02


POWERGRID 17.09.06 19:00

A/T due to operation of Over Voltage stage-I protection at Kolhapur MSETCL end. D/T signal received at Mapusa end.

3.83

400kV Chandrapur

17.09.06 07:49


MSETCL 18.09.06 11:24

A/T on R-N fault. R (RYB) ph conductor snapped at Loc. no. 224 near Pandharkawada town.

3.84

400kV Chandrapur

17.09.06 13:07


MSETCL 14:10 Line A/T on O/V Stage-I due to operation of in built O/V function of Main 2(Micom P442). O/V setting 108% - 5sec.

3.85

400kV Chandrapur

18.09.06 13:38


MSETCL 14:25 Line A/T on O/V Stage-I due to operation of in built O/V function of Main 2(Micom P442). O/V setting 108% - 5sec.

3.86

400kV Chandrapur

18.09.06 14:36


MSETCL 14:36 A/T on transient Y-ph to E/F. A/R successful at both ends.

3.87

400kV Khandwa

19.09.06 18:29


POWERGRID 18:51 A/T on transient Y ph to E/F. Line A/R at Khandwa end only.

3.88

400kV Chandrapur

20.09.06 14:35


MSETCL 15:26 Line A/T on O/V Stage-I due to operation of in built O/V function of Main 2(Micom P442). O/V setting 108% - 5sec. O/V setting for this line revised to 110% - 7sec on 23.09.06.

3.89

400kV Raipur

20.09.06 16:0

400kV Raipur- Bhadravati # 2

POWERGRID 21.09.06 06:31

A/T on transient R ph to E/F. Line A/R successfully from both ends however O/V stage-I protection operated at B’vati end resulting in three phase tripping.

3.90

400kV Mapusa

27.09.06 15:16


POWERGRID 15:27 A/T due to operation of Over Voltage stage-I protection at Kolhapur MSETCL end. D/T signal

Minutes of 95th PCM

received at Mapusa end. 3.91

400kV Mapusa

28.09.06 17:01


POWERGRID 30.09.06 11:17


3.92

400kV Boiser

29.09.06 13:49

400kV Tarapur- Boiser # 2

POWERGRID 14:45 A/T due to R ph to E/F. Line A/R at Boiser end only. A/R selector switch was kept in non -auto mode at TAPP end.

3.93

400kV Mapusa

30.09.06 17:09


POWERGRID 04.10.06 11:43


Minutes of 95th PCM

MINUTES OF THE 95th PROTECTION COMMITTEE MEETING … · MINUTES OF THE 95th PROTECTION COMMITTEE...

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Transcript of MINUTES OF THE 95th PROTECTION COMMITTEE MEETING … · MINUTES OF THE 95th PROTECTION COMMITTEE...