baart sarkar government of india kond`iya ivavut p`aiqakrna · 2009-01-02 · natural environment...

Baart sarkar Government of India kond`Iya ivaVut p`aiQakrNa

Central Electricity Authority piScama xao~Iya ivaVut saimait

Western Regional Power Committee ef -3, emaAayaDIsaI xao~, AMQaorI (pUva-), mauMba[- - 400 093

F-3, MIDC Area, Andheri (East), Mumbai - 400 093

Aa[- esa Aao : 9001-2000 ISO : 9001-2000

dUrBaaYa Phone: 022- 28221681; 28200194/195/196; fO@sa Fax : 022 – 28370193 Website : www.wrpc.nic.in E-mail : [email protected]

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Kanha (M.P.). Ÿ¸−¸½™¡¸ / Sir,

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Please find enclosed herewith the minutes of 103rd Protection Committee Meeting of Western Regional Power Committee, Mumbai held on 12th & 13th December 2008 at Kanha (M.P.), for your information and necessary action.

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š¸›¡¸¨¸¸™ /Thanking you

ž¸¨¸™ú¡¸/Yours faithfully,

(‡¬¸.”ú.’¸ˆÅ¬¸¸¿”½/S.D. Taksande) ‚š¸ú. ‚¹ž¸.(£.)/Suptdg. Engr.(P.) ¬¸¿¥¸Š›¸ /Encl. :- „œ¸£¸½Æ÷¸¸›¸º¬¸¸£ /As above

Minutes of 103rd WRPC PCM

MINUTES OF THE 103rd PROTECTION COMMITTEE MEETING

The 103rd Protection Committee Meeting of WRPC was held on 12th & 13th

December 2008 at Kanha (M.P.). The list of participants is placed at Annex -I.

Shri N. Ravikumar, GM(O & M), WRTS-I, PGCIL welcomed the members &

participants to the 103rd Protection Committee Meeting. He stated that,

shortcomings in the design of power system equipments cannot be overcome by

field engineers, but they have protection of equipments in their hands to take care

of these deficiencies through proper protection relaying co-ordination. The

protection engineers should be open to ideas of newer technological changes and

should always try to remove deficiencies in the protection relaying and also

should adopt best maintenance practices.

Shri P.Patel, Member Secretary, WRPC, welcomed all the members and invitees

on behalf of WRPC to the 103rd Protection committee meeting. He thanked

PGCIL., for having willingly consented to host this meeting in a beautiful and

natural environment of Kanha National Park far from city, and also for making

excellent arrangements for the meeting and comfortable stay of the participants.

He stated that improvement in the performance of the protection system should be

achieved by analyzing the differences in setting of protection relaying systems.

He further stated that the CBIP and WRPC protection manual referred by

protection engineers is around 10 years old and the facilities and concepts

extended by the modern day relays have changed over the years. Also in view of

the changes in power system conditions over the years and modern day protection

relaying systems, these protection manuals needs to be reviewed so that

uniformity in the protection system relaying could be adopted. He further told that

the 1st study group meeting on the occurrence at VSTPS on 22/07/07, was held at

WRPC Mumbai and some more inputs were required by the study group for

analyzing the event and arriving at final conclusions. He hoped that various

protections related issues would be resolved during this two days meet at Kanha.


He then requested Shri S. D.Taksande, Superintending Engineer (Protection),

WRPC to take up Agenda items for discussion.

Item No.1: Confirmation of Minutes of 102nd Protection Committee Meeting.

Superintending Engineer (Protection), WRPC, stated that Minutes of 102nd PCM held on

17th & 18th Sept.2008 at Ahmedabad, were circulated vide WRPC letter no. Prot./102-

PCM/2008/WRPC/10008 dated 06th October 2008. Comments received from NPCIL vide

their letter no. NPCIL/Trans./2008/M/134 Dt 23.10.08 and PowerGrid vide their letter No.

WRTS/O&M/R/141/860 Dt.27.10.08, regarding Item No.6.03 of the minutes were

discussed. It was agreed to modify the last Para of Item No.6.03 as under,

“Committee discussed the relay settings and coordination issue of TAPS-1 & 2,

TAPS-3 & 4 and associated feeders of the network at length. It was felt that co-

ordination between main distance protection with backup protection relay

(whose reach is uncertain) is a tricky problem and any attempt will never give

complete results. Therefore numerical distance relay with appropriate

specifications could solve the co-ordination problem. Also time co-ordination

can be achieved by co-ordination of the zone-2 timings.

Committee felt that even for smaller length lines of the order of 800 meters,

numerical distance protection schemes are feasible and TAPS should go for

numerical relays instead of only backup relays.

PGCIL representative agreed to increase the time delay of Zone-2 distance

protection of 220kV Boisar-TAPS 3&4 line at Boisar end from existing 200msec

to 400msec and TMS setting of 67 N relay at TAPS 3&4 end of 220kV TAPS

3&4-TAPS1&2 line may be adopted so that it operates within 300msec. Also

NPCIL shall commission the numerical distance protection scheme at the

earliest.”

With these modifications the Minutes of 102nd PCM circulated vide above referred letter,

were confirmed.


Item No.2: System disturbances

2.01: System disturbance at Gandhinagar TPS in GSECL system on 03-07-2008

GSECL representative informed that on 03-07-2008 at 14:50 hrs, while taking planned

shut down of Unit No.5 (connected to Bus A) for AOH , at Gandhinagar TPS, Local

Breaker back-up (LBB) protection of GT-5 operated, due to which all the 220kV Lines,

Transformers, Generators connected to Bus A and Bus Coupler tripped on operation of

bus bar tripping relays 96.

There was a delayed opening of Y pole of the Unit No.5 Circuit Breaker. CGL engineer

was called for attending the problem. Measurement of the Circuit Breaker timings was

carried out and timings were found same for all the three phases. Mechanical problem

was found in the operating mechanism of the breaker CGL Engineer attended the same.

GETCO representative further told that the PDR time setting is 500msec.

220 kV Bus A was charged at 15:15 Hrs. & 220 kV Lines, Transformers and Generators

were taken in service by 19:12hrs of 03.07.08, except Generator 5(under AOH) which

was taken into service at 01:50hrs on 22.07.08

Committee felt that Generating Unit No.5 might have tripped due to operation of the

reverse power flow relay, however due to delayed opening of the Y phase Pole (due to

mechanism problem), the LBB protection might have operated.

Committee recommended that regular lubrication of the breaker mechanism should

be carried out to avoid these types of problems. Also PDR timings of

Generator/Transformer breakers (where A/R is not provided) can be adopted less

than LBB time settings to avoid operation of LBB ahead of PDR and thereby

unnecessary tripping of the Bus section, in the event of tripping command not getting

extended to the trip coil or one of the trip coils of a pole is faulty. However Comiittee

felt that since there was a mechanical problem in Y phase pole resulting in delayed

opening of the pole, the operation of LBB ahead of PDR could not have been avoided

in this case by adopting the above philosophy.


2.02: System disturbance at 220 KV Haldarwa S/S in GETCO system on 10-07-2008

GETCO representative informed that on dated 10.07.2008 at 15.55 hrs., there was a

heavy noise on 132kV side of switchyard in 220kV Haldarwa S/S resulting in tripping of

220kV lines and transformers.

Bus Bar Protection (EE make, PBDCB type) blocked LED indication appeared on the

Bus Bar Protection Panel. All the feeders connected to Haldarwa S/S tripped from remote

ends.

During yard inspection the C.T cable from J.B to M.K box of 220kV GPEC -1 Line was

found grounded (i.e. between cores and core to ground), this might have resulted in

blocking of bus bar scheme. Also there was a transient fault on the 220kV GPEC -1 Line,

which was not cleared from Haldarwa end due to shorting of C.T cable of 220kV GPEC-

1 Line. It was cleared from GPEC end.

All the feeders connected (Bus-1 and Bus-2) to Haldarwa S/S fed the fault, since the bus

coupler breaker was in service. Though the fault was on Bus section 1 at 220 KV

Haldarwa S/s, the Bus Bar Protection scheme could not clear the fault since it was in

blocked condition.

From the DR data of Kawas-1 it is evident that the fault was on 220 kV Bus (reverse

zone) and it has taken 391.7 m sec to clear the fault. The fault might have been highly

resistive, since the fault current recorded is 1.6KAmps and fault resistance recorded is

1.84Ohms.

.IR values of R & B ph LA of 100MVA 220/132kV EMCO make T/F. No.1, were found

low (i.e.250 M ohm) also IR value of R ph LA of 100MVA 220/132kV EMCO make T/F

No.2, was found low (i.e. 250 M ohm). The LA’s were replaced.

GETCO representative further informed that it was raining at the time of this occurrence.

The fault level at Haldarwa S/S is 43.52 kA and the maximum setting available with the

Bus Bar Protection scheme is less than the corresponding fault current of 30kA.

All the tripped Lines and transformers were restored by 19:05hrs. on 10.0708, except T/F

No 2, which was restored at 20:40hrs on 11.07.08


Committee felt that T/F No.2 tripped correctly on operation of Differential Relay for

220kV side R ph LA fault. T/F No.1 differential relay had not operated and its

Directional E/F relay had operated resulting in delayed clearance of the fault of

220kV side R and B ph LA’s of T/F No.1 since the IR values of the above LA’s were

found very low during testing.

Committee also felt that the Bus Bar protection scheme blocked indication might

have appeared due to open circuit in the CT secondary wires of 220kV GPEC line,

and thereafter might have converted into short circuit of cores with earth.

Committee observed that since the fault level of 43.52KAmps is quite high at

Haldarwa S/S, the Bus Coupler Breaker should be kept OFF, so that the fault level of

the S/S remains low and would improve the through fault stability of the Bus Bar

Protection scheme. Also maintenance/inspection of the cable trenches should be

carried out regularly and the healthiness of the CT/PT secondary cables should also

be checked at the time of relay testing.

2.03 System disturbance at Kutch Lignite Thermal Power Station (KLTPS) in

GSECL system on 25-07-2008

GSECL representative informed that on 25-07-2008 at 06:55 Hrs. Bus I Differential

protection operated (with indication R,U), due to which all the 220kV lines, transformers

and generators connected to Bus I, tripped on operation of bus bar tripping relays 96, at

KLTPS

The R phase insulator of 89A isolator of Akrimota line – 1 was flashed. The weather was

cloudy and huge chattering was observed during above tripping.

220 kV Bus I Charged at 07:20 Hrs, and all the equipments were restored by 09:20hrs,

except 220kV Akrimota line – 1 which was restored at 18:45hrs on 25.07.08, after

replacing the defective insulator. GSECL representative further informed that the line voltages observed at the S/S’s in the

region are in the range of 240-245kV most of the time.

Committee observed that the operation of Bus-I differential protection is in order and

failure of insulator may be due to polluted environment and system over voltages in


the region.

Committee recommended for replacement of existing Silicon coated insulators,

regular hot line washing and improvement in system voltage profile in the region as

this would minimize such occurrences.

GSECL representative informed that to get rid of the over voltages bus reactors of

50MVAR capacity have been planned for installation at 220kV Nakhatrama and

Akrimota S/S’s

2.04: System disturbance at Sikka Thermal Power Station in GSECL system on

27-07-2008

GSECL representative informed that on 27.07.2008 at 05:40Hrs, sound of flashover was

heard and simultaneously the Bus Bar Differential protection of Bus B operated resulting

in tripping of all lines, transformer, generators and Bus Coupler connected to Bus B at

132kV Sikka TPS

During yard inspection it was found that the flexible jumper of 89 C Bus side isolator of

132kV Bhatia line was melted and was found disconnected. This disconnected jumper

might have touched to ground resulting in a Bus B fault.

The flexible jumper was replaced and all such jumpers were tightened.

All the tripped feeders and equipments were restored by 08:53Hrs of 27.07.08.

Committee observed that the operation of Bus B differential protection is in order.

Committee recommended that thermo vision cameras should be provided at

important 220kV, 400kV S/S’s for monitoring of the hot spots, and at least quarterly

monitoring of the hot spots at important 132kV S/S’s should also be carried out.

2.05: System disturbance at 220kV Morbi S/S in GETCO system on 28-07-2008

GETCO representative informed that on 28-7-2008 at 3:40 hrs, 220 kV Dhrangdhra -

Morbi and 220 kV Hadvad – Morbi lines, emanating from 220kV Morbi S/S

developed line faults simultaneously. There was a Y and B Ph fault (Disc insulator

failure at @ 6 Km from Morbi) on 220kV Dhrangadhra line and R & B Ph. Fault (disc


insulator failure at @ 13 Km from Morbi) on 220 kV Halvad line.

220 kV Morbi Halvad line tripped from both ends correctly. Distance protection scheme

operated in zone 1 from Morbi end, and on carrier trip at Dhangadhra end of the 220 kV

Morbi- Dhrangadhra line, but all the three poles of breaker did not open simultaneously

at Morbi S/S. The B –Ph pole opened after a delay of 268 m sec, as seen from the DR

data of 400kV Hadala S/S. The pole discrepancy timer setting is 500 m sec and LBB

operation time setting is 200 m sec. Before the breaker could trip on pole discrepancy,

LBB operated and tripped all the lines connected to Morbi S/s, resulting complete failure

of supply.

GETCO representative further informed that since there is single bus arrangement at 220

kV Morbi S/S, LBB scheme has been put in service to clear the bus fault faster. The Bus

Coupler erection work is in progress and after commissioning of the Bus Coupler the

transfer bus would be utilized through Bus Coupler for maintenance of the breakers of the

S/S.

Normalcy of the system was restored by 04:00hrs.

Committee observed that operation of LBB because of non clearance of the fault for

268 msec due to mechanical problem of B phase pole is in order and felt that the Bus

Coupler should be commissioned at the earliest so that routine maintenance of the

breakers in the S/S could be carried out regularly.

2.06: System disturbance at 400 kV Nagda S/S in MPPTCL system on 29-07-2008

MPPTCL representative informed that on 29.07.2008 at 03:28Hrs, BHEL make

400/220kV, 315MVA transformer commissioned at 400kV Nagda S/S on 28.05.1992,

tripped from both sides. At the time of tripping no other tripping occurred at 400kV Nagda

S/S or remote S/S’s. Simultaneously the transformer bushing caught fire causing complete

damage to the T/F. To avoid damage to the protection-relaying panel, the control panel

D.C supply was switched OFF. The breaker control cables of 220kV breaker, which were

laid in the same trench used for this ICT got burnt due to the fire. The data downloaded

from the AREVA make. P633 Numerical Differential Relay, indicated that the T/F tripped

on Differential protection in 79 msecs.


MPPTCL representative further informed that during routine maintenance in the month of

April 2008, the T/F was tested and the test results were satisfactory. The tan delta values

were found to be consistent in the range 0.005. Also fire-emulsifying system is not

installed at the S/S. The faulty T/F was replaced on 3rd December 2008.

Committee felt that the ICT might have caught fire due to bursting of the bushing

before clearance of the fault, although the differential protection operated correctly.

Committee observed that fire-emulsifying system should be provided in the S/S, at the

earliest.

2.07 : System disturbance at 220kV Gavasad S/S in GETCO system on 09-08-2008.

GETCO representative informed that on 09.08.2008 at 4.15 hrs, 220kV feeders on Bus A

and Bus coupler breaker tripped at 220kV Gavasad S/S. There was no zone indication on

Bus bar panel. The trip signal was persistent and was not getting resetted.

There was no actual bus fault. The relay modules were removed for inspection. Lot of

waste of mice & lizard was found in measuring and tripping modules of zone –A of

RADSS scheme. The terminals meant for final tripping of zone-A were found shorted.

The modules of Zone –A bus bar were thoroughly cleaned. Also the bus bar protection

relay panels were cleaned thoroughly. Proper vermin proofing is also done

The scheme was tested for Zone A operation by injecting current. The scheme was put

under observation on 09/08/08.

All the feeders were transferred on Bus B to attend the isolator operating and alignment

problems. On completion of Isolator problems by 25/8/08 the feeders will be transferred

on Bus A.

Committee felt that the above occurrence occurred because of negligence in

maintenance of the S/S equipments. Regular cleaning/maintenance of the S/S should

be carried out. Committee recommended that vermin proofing should be done in the

vermin encroach able areas of the control panel/circuits of the S/S.


2.08: System disturbance at 220 kV Khaparkheda S/S in MSETCL system on

10-08-2008

MSETCL representative informed that on 10.08.2008 at 01:25Hrs, the Y Phase CT (ABB

make, Year of Manufacture 1999, Commissioned on 16.02.2006) of 220kV Kalmeshwar-

Khaparkheda feeder, caught fire and got burst, at 220kV Khaparkheda S/S. All the feeders,

Gen Unit 2, Gen Unit 3, Station T/F 2(40MVA) and Station T/F 3 (40MVA) connected to

220kV Bus-I, including bus coupler, tripped at Khaperkheda S/S, on operation of Zone-I,

bus bar protection. 250MVA GT1 which was connected to 220kV Bus-II, also tripped due

to failure of auxiliary A.C. supply of this GT. The auxiliary supply to GT1 was fed through

T/F 2, since its own station T/F (T/F-1) was under outage for maintenance. The 220kV

Khaperkheda-Kalmeshwar feeder tripped on DPS Zone-I from Kalmeshwar end. Due to

bursting of Y phase CT mechanical damage to R,Y, and B phase CVT’s and R and B phase

CT’s was observed. All damaged CVT’s and CT’s were replaced.

Normalcy of all the feeders and Generating units was restored at 08:04hrs on 10.08.2008,

except 220kV Kalmeshwar bay, which was restored at 23:06hrs on 12.08.2008.

MSETCL representative further told that the tan delta results of CT, taken 9-10months

before this occurrence were satisfactory.

Committee felt that failure of CT’s within such a short span is unjustifiable, and

observed that the CT’s of particular batch and manufacturer installed in the areas of

other constituents had also failed. Hence Committee desired that constituents should

submit list of ABB make CT’s failed recently so that the matter could be taken up

with M/s ABB

2.09: System disturbance at 220 kV TAPS S/S in NPCIL system on 05-09-2008.

NPCIL representative informed that on 05.09.2008 at 07:07hrs, the R-Phase

tension/suspension insulator string flashed over at low level gantry just before take off

tower of 220kV TAPS-Bhilad Line at TAPS 1&2 switchyard. 220kV Zone-1 Bus

Differential relay operated for the nearby through fault on 220kV TAPS-Bhilad feeder.

The DPS at TAPS end had operated in Zone-1 and Dir E/F and DPS Zone-2 at other end,

however all the lines and Gen.Unit-2 tripped at TAPS.


NPCIL representative further informed that the 220kV Bus Bar Differential relays are 40

years old (ABB make RYDA type) and the maximum setting available in the relay is less

than the actual fault level for the through fault stability of the Bus Differential relay since

the fault level at the S/S is quite high.

It was raining and lightening at the time of occurrence.

Committee felt that the Bus differential protection might have operated for through

fault, due to high fault level of the S/S and old Bus differential relay. Committee

desired that the existing Bus differential relay should be replaced by modern

numerical Bus Bar protection scheme. NPCIL representative informed that the

process of procurement of the Bus Bar protection scheme has been initiated and the

existing scheme would be replaced with the new scheme.

Committee also felt that due care should be taken in the maintenance of lines

emanating from this S/S by the constituents concerned.

2.10: System disturbance at 400 kV Padghe S/S in MSETCL system on 23-09-2008.

MSETCL representative informed that on 23.09.2008 at 00:49hrs, the 400kV side Y phase

CT of 3x105MVA, 400/220/33kV ICT No.1, connected to Main Bus-II failed at 400kV

Padghe S/S. ICT No.-1 tripped on operation of Differential protection, simultaneously the

400kV Main Bus-II bus bar protection operated resulting in tripping of all the equipments

connected to Main Bus-II.

MSETCL representative further informed that Tan delta results of the 400kV BHEL

make(YOM:1998, repaired and commissioned on 22.03.07) Y phase CT were satisfactory.

The 400kV Padghe-Tarapur-I line which was connected to 400kV Main Bus-I also tripped

on mal operation of distance protection relay (THR-ER make) on “LC-line check (SOTF)

feature” at Padghe end. The 400kV Padghe-Boisar (PGCIL) which was connected to Main

Bus-II, did not trip at Boisar end on DT signal due to operation of busbar protection at

Padghe S/S.

MSETCL representative informed that during testing the 400kV Padghe-Tarapur-I DPS

scheme it was observed that the “LC-line check (SOTF) feature” was operating for all

phase faults and line to earth faults due to faulty card in the relay the same was replaced.


Also the DT card in the PLCC ckt of 400kV Padghe-Boisar (PGCIL) line at Padghe end

was faulty the same was replaced

All the affected lines and equipments were restored by 11:42hrs on 23.09.2008.

Committee felt that the operation of 400kV Main Bus-II was in order.

2.11: System disturbance at 400 kV Korba (W) S/S in Chatiagarh system on

29-09-2008

CSEB representative informed that on 29.09.2008 at 12:59 hrs 220kV Korba (W)-Mopka

S/C tripped on R-phase fault. The line was carrying about 220MW just before the tripping.

The 400/220kV, 500MVA ICT at Korba (W) was loaded to about 350MW (from 220kV to

400kV) just before the above tripping. The above ICT got critically loaded to 566MW

consequent to tripping of 220kV Korba (W)-Mopka Ckt, and tripped on overload leading

to tripping of 220kV lines connected to it.

The above trippings resulted in islanding of Korba (E)-Raigarh-Mopka-Banari-Bemetara-

Kotmikla areas of Chattisgarh system with a generation of 1100MW and a load of about

450MW. The island frequency rose to 51.99 Hz due to excess generation of around

650MW and the frequency of the N-E-W grid dipped to 49.15 Hz from 49.36Hz (prior to

islanding) and then to 48.8Hz due to loss of around 650MW of import from the island.

Due to the tripping of all the evacuating lines from IBTPS, both the IB units tripped. Due

to high frequency in the island, the units K(E) Ext-1 (250MW) generating around 180MW,

K(E) Ext-2 (250MW) generating around 180 MW, K(E)-6 (120MW) generating around

80MW and Jindal-4 (250MW) generating around 200MW totaling to around 640MW

tripped on over frequency. With the tripping of these units, the generation in the island was

in the order of 500MW and the island survived.

CSEB representative further informed that the 500MVA ICT is provided with IDMT over

current relay with 100% Plug Setting also the procurement process of additional ICT of

500MVA had been initiated and it is in tendering stage.

The 400/220kV Korba (W) ICT was synchronized at 13:05hrs and the above island was

brought back into main grid.


Committee observed that .

(i) Alarm should be provided for over loading of the 500MVA ICT so that the

operator would get sufficient time to act.

(ii) The 100% O/C setting of the IDMT relay is too conservative and as an

immediate measure CSEB should consult the manufacturer of the ICT (i.e.

BHEL) for the over current setting of 150%. The IDMT relay provided for

over load protection should be replaced by DMT relays.

(iii) This event highlights the local load management problem. Under such

eventualities proper load shedding should be done at Mopka S/S. Also

load-trimming schemes should be provided in Raigad and Mopka areas.

(iv) To avoid shooting up of frequency in an islanded operation and over

frequency tripping of the Generators, CSEB should think on the scheme of

backing down of their own Generation.

ITEM NO. 3: Tripping of lines / ICTs:

The incidences of tripping of lines and ICTs during the period 01-07-2008 to30-09-2008

were discussed during the meeting.

Observations of the committee are enclosed at Annexure –3.

ITEM NO. 4: Protection related recommendations on Grid Disturbances in Western

Regional Grid on 25.2.2007 at 1634 hours and 28.2.2007 at 13:11 hours:

Protection related recommendations of the Enquiry Committee on Grid Disturbances

in Western Regional Grid on 25.2.2007 at 1634 hours and 28.2.2007 at 13:11 hours

were reviewed during the meeting and the present status regarding implementation of

recommendations is placed at Annexure-4.


ITEM NO.5: Follow up points:

5.01: Procurement of new Busbar protection scheme at 400 KV Nagda MPPTCL S/S:

PowerGrid had requested for early commissioning of Bus Bar Protection Scheme

at 400kV Nagda S/S in view of importance of the 400kV Nagda S/S in the WR

grid. During 102nd PCM MPPTCL representative informed that Bus Bar

protection panel of Eassun Reyrolle make for 220kV side and REB 670 ABB

make for 400kV side had arrived at site. However due to failure of 315MVA T/F

at Nagda S/S, the commissioning of new busbar protection scheme was deferred

MPPTCL representative informed that the 315 MVA T/F had been replaced

and the new bus bar protection scheme is expected to be commissioned by 1st

week of January 2009.

5.02: Implementation of Revised Mumbai Islanding Scheme:

MSETCL vide their letter No.SE/TCC/Vashi/642 Dt. 04.11.2008 and Reliance

Energy vide their letter Dt. 05.09.08, have intimated that the revised Mumbai

Islanding Scheme, as recommended by the Enquiry Committee on Grid

Disturbance of 25th & 28th February, 2007, has been commissioned, tested and

taken into service at 220kV Boisar (MSETCL) S/S, on 19.10.2008.

REL representative explained the scheme and its implementation details.

Committee noted the same.

ITEM NO. 6: Other grid points:

6.01: Configuration of direct trip PLCC protection scheme for 220kV lines

emanating from PGCIL S/Ss to utilities.

(i) During the discussions in the 102nd PCM, MPPTCL representative had

informed that the PLCC scheme provided on feeders connected to PGCIL at

220kV Pithampur and Rajgarh S/S’s were suitable to transmit and receive


direct trip as well as permissive trip command. PGCIL representative

informed that the scheme had been tested and put into service at their

end also.

(ii) GETCO representative informed that direct trip PLCC for 220kV Bhilad-

Vapi feeder is pending for want of outage, the same would be

commissioned by the last week of December 2008.

(iii) MSETCL vide their letter No. SE/TCC/Vashi/297 dated 12 May 2008 had

informed that direct trip PLCC protection scheme for 220kV Boisar –

Boisar I & II feeders had been taken into service on 07.12.2007 and

09.05.2008 respectively at 220kV Boisar (MSETCL) S/S. Regarding direct

trip PLCC protection scheme in respect of 220kV Boisar(PGCIL) –

Padghe feeder, the same has been taken into service on 22.08.08.

6.02: Revision of settings of df/dt UFLS relays in WR grid

The WRP Committee in its 7th meeting held on 3rd May 2008, had approved

revision of df/dt relay settings to be implemented w.e.f. 1st July 2008. In the 101st

PCM, members were requested to implement the following revised settings

approved by the WRP Committee, for which all the committee members had

agreed.

Stage Settings

(Hz)/(Hz/

Sec)

Total

Load

Relief in

Region

(MW)

Load shedding (MW) to be effected by

GETCO MPPTCL MSETCL CSEB TPC

Stage I 49.9/0.1 2000 1006 361 546 27 60

Stage II 49.9/0.2 2000 905 355 621 37 82

Stage III 49.9/0.4 2472 1001 392 686 120 273

Total 6472 2912 1108 1853 184 415

Matter was discussed in 102nd PCM and representatives of GETCO, MPPTCL,

CSEB and TATA power informed that the revised settings of df/dt ULFS relays

have been implemented. MSETCL representative informed in the 394th OCC


meeting of WRPC that the revised settings have been implemented in their region

as well. But constituents have intimated that these relays are prone to mal

operation, leading to unwarranted tripping of feeders therefore requested for review

of setting of 0.1Hz in particular and base frequency of 49.9Hz in general.

Committee felt that the mal operation of these relays should be informed and

the problems faced by constituents needs to be compiled.

6.03: Non-availability of Event Logger at 400kV state owned sub-stations at

Nagda, Indore, Bina and Dhule.

PGCIL had informed that Event Loggers at some of the 400kV state owned Sub

stations, namely Nagda, Indore, Bina and Dhule are not provided. PGCIL have

requested for early installation of Event Loggers at these stations.

MPPTCL representative informed that event loggers for Nagda, Indore and

Bina S/S are under procurement process.

MSETCL representative informed that event logger for Dhule S/S is covered

under SMS program and the cable laying work is in progress and the same will

be completed within six months.

6.04: Pending SOE connections and erroneous data in SCADA.

During the 102nd PCM Add.G.M WRLDC stated that, in the existing ULDC

scheme (SCADA/EMS system), at some of the locations in WR, the CB contacts

are extended to the SOE inputs of the RTU, while at many other locations the SOE

connections are yet to be established. In order to have the correct analog and status

data through the SCADA/EMS system it is advantageous to configure the MTR

contacts to the SOE inputs of the RTU. The MTR contacts extended to the SOE

inputs of the RTUs, will help in the analysis of grid disturbance and the time

logging will be independent of the CB operation timings in cases where the

SOE input to the RTU is taken from CB contacts.

Also the critical data both analog and status acquired from some of the locations is

found to be erroneous, due to which the results of power network analysis module


are not of very good quality.

Member Secretary WRPC, in 102nd PCM, stressed the importance of receiving,

correct time logging of tripping elements, correct status of elements and correct

analog data, through SCADA. He further requested constituents to take corrective

actions immediately and convey the compliance.

Committee discussed the issue and requested WRLDC to give the list of the

status of pending and erroneous SOE connections and also opined that

constituents should confirm the availability of hardware at RTU’s for

incorporating the extension of MTR contacts to the SOE inputs of the RTU, in

addition to the CB contacts which are also required to be transmitted.

The list of status of pending and erroneous SOE connections submitted by

WRLDC is enclosed as Annexure in the Minutes of 103rd PCM posted at our

web site www.wrpc.nic.in.

6.05 : Current setting for LBB relay’s of 400kV Lines

Power Grid vide their letter No. WRTS/O&M Dt.14.11.08, have informed that on

11.11.08 Main-I & II of 400kV Koradi-Bhilai Line operated at Bhilai end, however

due to failure of the pneumatic system of the breaker the fault was not cleared for

around 3 minutes due to non operation of LBB relay within 200msec, since the fault

was of high resistance nature. Non operation of LBB relay in time is mainly due to

higher current setting of 1.2 Amps(corresponding to 1200Amps on Primary side),

adopted at Bhilai S/S

PowerGrid have suggested to change the LBB relay current settings from 1.2 Amps to

0.2Amps.

Committee discussed the issue and felt that the current settings for LBB relays

should be set to 0.2Amps for 400kV and 220kV lines as per the recommendations

given in the C.B.I.P. manual.


ITEM NO. 7: System disturbance at 400 kV VSTPS Vindhyachal S/S in NTPC system on

22-07-2008

As discussed during 102nd PCM, a study group comprising of members from WRPC,

WRLDC, VSTPS, Powergrid, GSECL and MSETCL has been formed by Member

Secretary, WRPC to look into the matter in detail and analyze the incidence and come

up with remedial measures to avoid such occurrences.

Superintending Engineer (P), WRPC informed that the 1st Study Group Meeting

was held at WRPC Mumbai on 11.11.08. The Study group felt that some more

inputs were required from NTPC Vindhyachal for analysis of the occurrence.

NTPC was requested to furnish the inputs at an early date to enable the Study

Group to discuss and finalize its report.

ITEM NO. 8: Any other issues:

A presentation on “Application of latest testing methods and audit of critically located

substations for operation of grid with reliability and security “ was presented by Shri Ravi

Wadyalkar Dy.Manager WR-I, PGCIL.

The presentation is posted at our web site www.wrpc.nic.in .

Committee appreciated the efforts taken by PGCIL on the preventive maintenance

of power system equipments.

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

It was decided that the next protection committee meeting (104th) will be hosted by

NTPC Vindhyachal, in March 2009, wherein system disturbances for the period

01/10/2008 to 31/12/2008 will be discussed. Exact date and venue will be

communicated separately.


ANNEX-I

LIST OF PARTICIPANTS

103rd Protection Committee Meeting held on 12th & 13th December, 2008 at Kanha (M.P.).

MSETCL (Maharashtra State Electricity Transmission Company Limited)

Shri J.G. Nandapurkar Dy. Executive Engineer (TCC), Nagpur

Shri D.P. Nandanwar Dy. Executive Engineer (TCC), Vashi

MAHAGENCO (Maharashtra State Power Generation Company Limited)

Shri A.K. Patil Superintending Engineer (T/F), Nagpur

MPPTCL (Madhya Pradesh Power Transmission Corporation Limited)

Shri Shyamji Tiwari Addl.Chief Engineer (LD)

Shri P.K.Gargav Executive Engineer (T&C), Ujjain MPPGCL (Madhya Pradesh Power Generation Corporation Limited)

Jaswant Singh Grover Chief Engineer (Thermal-Hydro Design)

GETCO (Gujarat Energy Transmission Corporation Limited)

Shri B.R. Panchal Addl. Chief Engineer (Testing), Baroda

Shri D.K. Panchal Ex.Engr.(T) GSECL (Gujarat State Electricity Corporation Limited)

Shri U.D. Adhvaryu Superintending Engineer (Testing), Baroda

CSEB (Chattisgarh State Electricity Board)

Shri Anil Dhar E E, CSEB.

Shri Mahesh K.Sharma E E.(Testing), CSEB, Korba

NTPC

Shri Jitendra Tiwari DGM (EM), VSTPS, Vindhyachal

Shri T.K.Rao DGM (EM), Korba


NPCIL (Nuclear Power Corporation of India Limited) Shri A.N.Thakur SME(E), TAPS, NPCIL

Shri K.P.Singh ACE(Trans), NPCIL

Shri B.M Shah SO/E (EM), KAPS, NPCIL

PGCIL (Power Grid Corporation of India Limited) Shri N. Ravikumar GM (O & M), WRTS-I, Nagpur

Shri M.G. Raoot G.M., WRLDC, Mumbai

Shri P.Pentayya Addl.G.M. , WRLDC Mumbai

Shri S.K.Mishra DGM, WRTS-I, Nagpur

Shri P.C.Sastry Chief Manager, 765kV Seoni S/S

Shri P.Biswas Manager, WRLDC Mumbai

Shri Anand Dubey Manager, WRTS-II, Vadodara

Shri Ravi Wadyalkar Dy.Manager, WRTS-I, Nagpur

TPC (Tata Power Company) Shri T. Muralikrishna Chief Manager, Trombay, Mumbai

REL (Reliance Energy Limited) Shri D.M. Devasthale Sr.Manager (Trans), Mumbai.

Shri S.S. Joshi Sr. Manager, TPS Dahanu

Torrent Power Shri Ketan S. Shah Assit. Manager(EHV), Ahmedabad.

WRPC (Western Regional Power Committee) Shri P. Patel Member Secretary

Shri S. D. Taksande Superintending Engineer (P)

Shri P.D.Lone Assist.Dir.-I(P)


ANNEXURE-3

TRIPPINGS OF LINES / ICTS

Tripping Restoration Sr. No.

NAME OF S/S

Name of line/ICT

SYSTEM /Provision

of A/R (Yes/No) Date Time Date Time

REASON

3.01 400 KV Kasor 400 KV Kasor-GPEC

GETCO Y 01.07.08 2:27 04.07.08 19:30

At Loc No.228(S) Y-Ph, Loc.No.209(S)R Ph & loc No.231(S) B-Ph disc insulator flash over.

3.02 400 KV Amreli 400 KV Amreli-Jetpur

GETCO Y 01.07.08 4:25 01.07.08 15:46 At Loc No.615(S)-B ph string

insulator flash over.

3.03 400 KV Kasor 400 KV Kasor-SSP

GETCO Y 02.07.08 3:06 02.07.08 21:55 At loc.no.117(S) R-Ph disc

insulator flashover.

3.04 Deleted

3.05 400kV Indore 400kV Indore-Asoj Ckt.-II

PowerGrid Y 02.07.08 5:37 03.07.08 18:13

Line tripped from both end A/R at Asoj end only, due to insulator flashover at Loc.No.758A.

3.06 400kV Indore 400kV Indore-Asoj Ckt.-I

PowerGrid Y 02.07.08 6:38 02.07.08 18:15

Line tripped from both end A/R at Asoj end only, due to transient fault

3.07 400kV Indore 400kV Indore-Asoj Ckt.-I

PowerGrid Y 04.07.08 4:17 04.07.08 9:15

Line tripped from both end A/R at Asoj end only, due to transient fault

3.08 400kV Bhilai 400kV Bhilai-Koradi

PowerGrid Y 05.07.08 5:06 05.07.08 5:06 A/R successful at both

ends on R-N fault.

3.09 400kV Vindhyachal

400kV V'chal-Jabalpur Ckt.IV

PowerGrid Y 06.07.08 23:31 07.07.08 0:46

A/R successful at Jabalpur end but A/T due to receipt of D/T from VSTPS. B-E fault. Patrolling carried out no abnormality observed. CGL make breaker B-Ph A/R problem.

3.10 400 KV Asoj 400 KV Asoj-Indore-2

GETCO Y 10.07.08 4:20 10.07.08 4:50 A/R successful. Transient

tripping.

3.11 400kV Nagda

400kV Nagda-Dehgam Ckt.I

PowerGrid Y 10.07.08 13:01 11.07.08 15:07

A/T at both ends on R & Y ph-ph fault. Decapping of top(Yph) insilator string at Loc. No.324.

3.12 400kV Raipur 400kV Raipur-Sipat 3

PowerGrid Y 12.07.08 12:12 12.07.08 13:06

Line tripped at Raipur end on receipt of DT signal from Sipat end. Line tripping at Sipat end was on DPS. CVT problem at Sipat end.


3.13 400kV Bhilai

220kV Bhilai-Khedamara (PGCIL)

CSEB 17.07.08 13:06 17.07.08 19:27

Line tripped on operation of DPR as well as LBB. Conductor snapped at Loc.No. 5 DA-0

3.14 400kV Nagda 400kV Nagda-ISP

MPPTCL Y 21.07.08 13:27 21.07.08 14:28 A/R L/O M-2 protn. Optd. On

Rph fault.


GETCO Y 24.07.08 13:38 24.07.08 21:35

A/R lock out at Kasor end. Nothing found abnormal after patroling. Test charge taken and line stood O.K


GETCO Y 26.07.08 5:05 26.07.08 5:40 Over voltage stage I trip at

SSP end.

3.17 400kV Koradi 400kV Koradi-Sarni

PowerGrid Y 30.07.08 6:52 30.07.08 6:52 A/R successful at both end

on R-N fault


400kV V'chal-Jabalpur Ckt.III

PowerGrid Y 30.07.08 11:43 30.07.08 19:17

A/T from both ends on B-E fault. A/R unsuccessful due to failure of B ph V outer string at Loc.No.1000.

3.19 400kV Raipur 400kV Raipur-Bhatapara

PowerGrid Y 03.08.08 0:16 03.08.08 0:33 Line tripped on O/V. CVT

problem at Raipur end.

3.20 400kV Satna 400kV Satna-Bina Ckt.I

PowerGrid Y 03.08.08 17:51 03.08.08 18:33

Tripped at Satna end and A/T at Bina end, due to B-E fault. Main-I & II protn. Optd. Due to persistent fault of Main II, A/R unsuccessful (F/L-35.4% from Satna end)

3.21 400kV Raipur

400kV Raipur-Bhadrawati 1

PowerGrid Y 04.08.08 5:44 04.08.08 5:44

A/R successful at both ends on B-N fault. (F/L 10km from Bhadrawati)

3.22 400kV Chandrapur

400kV C'pur-Parli Ckt. 3

MSETCL Y 04.08.08 9:40 04.08.08 11:21

Line tripped on Y-N fault due to snapping of earth conductor between Loc.No.320 & 321


400kV V'chal-Korba 1

PowerGrid Y 04.08.08 12:51 04.08.08 14:40

Line tripped due to operation of NGR (oil leakage) PRV at Korba end. Line taken into service without shunt reactor as per WRLDC instruction.

3.24 Deleted

3.25 400kV Raipur 400kV Raipur-Bhatapara

PowerGrid Y 05.08.08 6:06 05.08.08 14:32

Line tripped on Y ph O/V stage-1 at Raipur end. CVT problem.

3.26 220kV KAPS 220kV KAPS-Vapi-1

NPCIL Y 06.08.08 19:30 08.08.08 17:30

Line tripped on pole discrepancy protection while taking outage for maintenance. The trip lever assembly and trip lever latch in trip control valve was faulty replaced the same. CGL Bkr mechanical problem.




PowerGrid Y 06.08.08 22:59 06.08.08 23:23

A/T from both ends on R-E fault (F/L 82.5% from Jabalpur)



PowerGrid Y 07.08.08 14:14 07.08.08 16:24

A/R from Jabalpur end only on transient Y-E fault(F/L 72.6% from V'chal). A/R was N/A mode at V'chal end. Thereafter line immidiately tripped on receipt pf Direct trip from V'chal end due to O/V at V'chal end.

3.29 Deleted

3.30 400kV Raipur


PowerGrid Y 11.08.08 16:15 11.08.08 17:09

Line tripped due to operation of Teed protn. , while testing work at Raipur S/S

3.31 400kV Dehgam

400/220kV ICT-I

PowerGrid Y 15.08.08 7:52 16.08.08 14:14

400/220kV ICT-I, tripped on T/F diff, O/C & E/F, due to external object fell on bushing.

3.32 400kV Kolhapur

400kV Kolhapur-Mapusa 1

PowerGrid Y 21.08.08 13:15 21.08.08 13:46 Line tripped on DC earth

leakage at Kolhapur end.

3.33 400kV Raipur


PowerGrid Y 22.08.08 8:51 22.08.08 9:33

Line tripped due to maloperation of reactor back up protection relay (timer faulty) at Raipur end.

3.34 220kV Korba

220kV Korba-Budhipadar 3

PowerGrid Y 22.08.08 13:25 22.08.08 14:24 Line tripped on R-E fault. (F/L

1.85km from Korba)

3.35 400kV Gwalior

400kV Gwalior -Agra

PowerGrid Y 23.08.08 3:31 23.08.08 4:04

400kV Main and Tie CB at Gwalior end tripped, due to operation of M-II relay and line remain charged from Agra end. Line charged from Gwalior end at 03:48hrs however line tripped from Agra end only. M-II relay had mal operated

3.36 220kV KAPS 220kV KAPS-Vapi-2

NPCIL Y 24.08.08 12:12 24.08.08 13:40 Line tripped on DPS Zone-1

Phase C , carrier aided trip.

3.37 400kV Sipat 400kV Sipat-Patadhi

PowerGrid Y 25.08.08 11:40 25.08.08 12:02

Line tripped at Patadhi end due to M-II relay maloperation.

3.38 400 KV Chorania

400 KV Chorania-Asoj

GETCO Y 25.08.08 12:01 25.08.08 14:20 Over voltage stage II trip at

Asoj end.


3.39 400kV Satna 400kV Satna-Bina Ckt.II

PowerGrid Y 25.08.08 13:58 25.08.08 14:55

A/R successful from both ends at 13:58hrs on B-E fault, however due to persisting B-E fault (98.4km from Bina end) generated 3ph trip. Patrolling report awaited.



GETCO Y 25.08.08 17:15 25.08.08 18:40 Over voltage stage II trip at

Asoj end.

3.41 400 KV Asoj 400 KV Asoj-Amreli

GETCO Y 25.08.08 19:41 25.08.08 19:50 Transient tripping.



GETCO Y 25.08.08 23:34 25.08.08 23:43 A/R lockout at both end. No

fault found.



PowerGrid Y 26.08.08 4:10 26.08.08 5:32

A/R from Jabalpur end only on transient R-E fault (F/L 388kms from V'chal). A/T from V'chal end Line was on transfer breaker at V'chal and CB air pressure was low.

3.44 400kV Koradi 400kV Koradi-Satpura

PowerGrid Y 26.08.08 11:55 26.08.08 11:55 A/R successful on R-N fault

(F/L 10.9% from Koradi)


400kV Korba-V'cha 2

PowerGrid Y 30.08.08 10:38 30.08.08 11:07 Line tripped on Bph fault.(F/L

319.2km from Korba)


400kV V'chal-Satna Ckt.III

PowerGrid Y 01.09.08 18:49 01.09.08 23:50

A/R successful at Satna end at 18:49hrs, however after 3sec DT recd. from V'chal end and line tripped again.(94.6% from Satna end) Jumper broken and fell on B ph line isolator.

3.47 400kV Raipur


PowerGrid Y 02.09.08 10:01 02.09.08 10:31 Line tripped on Ph-Ph fault

(F/L 149km from Raipur)

3.48 400kV Khandwa

400kV Khandwa-Dhule Ckt.I

PowerGrid Y 03.09.08 11:42 03.09.08 11:58 Line tripped due to persisting

B-E fault


PowerGrid Y 03.09.08 13:26 03.09.08 13:45

A/R successful from both ends at 13:26hrs on B-E fault, however due to persisting B-E fault (56.1% from Satna end) generated 3ph trip because of less clearence

3.50 400kV Tarapur

400kV Tarapur -Padghe 2

PowerGrid Y 03.09.08 16:42 03.09.08 18:02 Line tripped on R-E fault (F/L

16.4km from Padghe)

3.51 400kV Tarapur


PowerGrid 04.09.08 15:26 04.09.08 16:14 Line tripped on R-E fault (F/L 40.5km from Tarapur)



PowerGrid Y 05.09.08 11:03 05.09.08 11:21

A/R successful from both ends at 11:03hrs on B-E fault, however due to persisting B-E fault (56.7% from Satna end) generated 3ph trip, because of less clearence.


PowerGrid Y 05.09.08 13:11 05.09.08 13:36

A/R successful from both ends at 13:11hrs on B-E fault, however due to persisting B-E fault (57.3% from Satna end)generated 3ph trip, because of less clearence.

3.54 400V Raigarh 400V Raigarh-Rourkela 1

PowerGrid Y 06.09.08 16:07 06.09.08 16:37

Line tripped on Y-E fault. (F/L 11.7km from Rourkela), due tp persisting fault.

3.55 400kV Bina 400kV Bina-Nagda Ckt.II

PowerGrid Y 07.09.08 13:37 07.09.08 14:22

A/R successful at 13:37hrs on B-E fault, but again tripped due to persisting B-E fault at 119.8km from Bina.


PowerGrid Y 07.09.08 18:58 07.09.08 18:58

A/R successful at both ends on Y-N fault (F/L 166.5km from Raigarh)

3.57 400kV Korba 400kV Korba-Korba(W)

PowerGrid Y 09.09.08 11:40 09.09.08 19:55

Line tripped due to snapping of Y phase conductor on Bus bar at Korba(W) CSEB bay, due to hot spot.



PowerGrid Y 09.09.08 15:57 10.09.08 15:40

A/T at both ends on R-ph to E/F. Line test charged at 16:14hrs but again A/T from both ends. R-ph V-string fail at Loc.No.165

3.59 400kV Tarapur


PowerGrid Y 09.09.08 16:51 09.09.08 18:02 Line tripped on Y-N fault. (F/L

74.9km from Tarapur)

3.60 765kV Sipat 765kV Sipat-Seoni-1

PowerGrid Y 09.09.08 18:59 09.09.08 21:10 Line tripped due to DT recd.

At Seoni.


GETCO 09.09.08 23:15 09.09.08 23:40 Transient tripping.

3.62 400kV Itarsi 400kV Itarsi-Indore Ckt.I

PowerGrid Y 11.09.08 11:46 11.09.08 12:23

A/T from Indore end, due to direct trip channel-2 send command wire at B-pole of tie CB in switchyard earth lekage.Cable damaged at Itarsi S/S

3.63 400kV Raipur 400kV Raipur-Sipat 2

PowerGrid Y 12.09.08 11:29 12.09.08 11:55

Line tripped due to wiring mistake while working in Tamnar-2 main CB relay panel at raipur S/S



PowerGrid Y 12.09.08 13:34 12.09.08 14:02 Line tripped on Y-N fault at

45.53km from Rourkela

3.65 400kV Indore 400kV Indore-Asoj Ckt.II

PowerGrid Y 12.09.08 23:35 Bus Bar protn. Optd. At Asoj

end.


GETCO Y 14.09.08 12:33 14.09.08 14:20 Over -voltage stage I at 400

KV SSP end 435 KV.

3.67 400kV Korba 400kV Korba-Bhatapara

PowerGrid Y 17.09.08 12:08 17.09.08 13:40 Line tripped on O/V stage 1

at Korba

3.68 400kV Korba 400kV Korba-V'cha 2

PowerGrid Y 20.09.08 11:24 20.09.08 14:05

Line tripped due to relay maloperation at V'chal(NTPC)

3.69 Deleted

3.70 400 KV Asoj 400 KV Asoj-Ukai

GETCO Y 20.09.08 21:37 20.09.08 22:47

Bus bar protection operated at Asoj due to D.C control cable found faulty .

3.71 400 KV Asoj 400 KV Asoj-Wanakbori

GETCO Y 20.09.08 21:37 20.09.08 23:07

Bus bar protection operated at Asoj due to D.C control cable found faulty .

3.72 400kV Satna

400kV V'chal-Satna Ckt.III

PowerGrid Y 21.09.08 11:47 21.09.08 15:26

A/R at Satna end at 11:47hrs & after 5.87sec DT recd from V'chal end. Transient Y-ph-Earth fault.

3.73 400kV Korba (E)

400kV Korba(E)-Budhipadar 3

PowerGrid Y 22.09.08 14:07 22.09.08 15:50 Line tripped on Y-N fault at

99km from Korba


GETCO Y 28.09.08 6:03 28.09.08 6:36 Over -voltage stage I at 400

KV SSP end 433 KV.

3.75 400kV Bhilai 400kV Bhilai-Seoni CSEB 28.09.08 12:24 28.09.08 13:48 Line tripped on DPS Main-I

&II. A/R Lockout.

3.76 Deleted


Annexure –4 Present status on recommendations pertaining to Protection of Inquiry Committee on grid disturbances of 25.02.2007 and 28.02.2007 Sr no

Recommendations

I

Decisions and Suggestions of PC for implementing the

recommendations II

Status

III

i) Both Main- I and Main –II protection on 400 kV Padghe- Nagothane Ckt-I is provided by ABB make REL 521 relays with same characteristic and settings thereby defeating the purpose of providing selectivity and discrimination of the fault. In line with Section 2 of CBIP Publication 274 of November 1999, Main-I and Main-II protection should be of different types and not necessarily of different make.

It was decided in the 99th and 100th PCM that as a first step all constituents shall identify and intimate such feeders where both Main-I and Main-II protections having similar characteristics are provided. Also wherever possible constituents shall swap the relays and achieve the objective of providing Main-I and Main-II protections having different characteristics of operation. Committee will review the progress made by constituents with regards to these identified feeders.

MSETCL intimated that on 400 kV Padghe – Nagothane ckt-I, Main-I and Main-II protections have been provided with different characteristic and settings at Nagothane and Padghe end. REL 521 Main-I relays provided at Padghe end replaced with Siemens make relay on 13th Sept 08.. In pursuant of the decision of the PC, MSETCL had submitted the information regarding the feeders having similar Main-I and Main-II characteristics, in respect of Nagpur, Nasik and Vashi Circles. It was once again stressed upon constituents that this


recommendation is to be implemented expediously, and report compliance of the decisions of previous meetings.

ii) The Committee observed that distance relay REL 521 does not have the feature of recording switching off of auxiliary DC supply to the relay as an internal event among recording of other related relay supervision parameters. For the grid disturbance of 25.2.2007, the time of switching off of DC auxiliary supply was very crucial information, which was not available. The possibility of incorporating the time of switching off of DC auxiliary supply as an internal event recording may be taken up with the manufacturer.

a) As agreed in 98th PCM MSETCL took up the matter of incorporating the time of DC supply off to relay as an internal event with M/S ABB.

b) For future procurement this requirement may be added in the specification of relays itself.

c) Committee in its 100th PCM suggested that as an alternative watch dog contacts available on fascia can wired up to log as an event on SER provided in sub -stations.

d) In 101st PCM the Committee suggested that in case SER is not provided in the S/s it is suggested that, wherever possible DC supply OFF contacts of Main-I & Main-II relays can be wired to Main-II & Main-I relays respectively, thus DC supply OFF event of both the protection schemes is stored in either of the relay.

A) ABB have intimated that whenever DC supply is switched off, relay can not function and hence event can not be stored “DC off “ as an internal event in a memory, so suggestion made by enquiry committee can not be implemented. Committee felt that reply of M/s ABB was satisfactory and recommended that suggestions made in 100th and 101st PCM’s to overcome the problem may be implemented.

iii) The triggering of disturbance recorders at Padghe substation gets initiated only with the relay operation. Therefore, disturbance recording would not take place if the

Committee discussed and recommended the following threshold values for current and voltages to trigger DRs during 100th PCM

a) High Voltages:-150 % 0f nominal voltage.

A) In 101st PCM MSETCL Nasik and Vashi informed that they


relay has not operated. The Committee recommends that the DRs should also have analog triggering signal from voltage/current/frequency threshold to ensure generation of DR data.

b) Low Voltages:- 70% of nominal voltage without any intentional time delay.

c) Over Current:-150% of rated

secondary current with time delay of 1 sec can be given for triggering DRs.

have implemented the decisions in most of S/Ss, and constituents were requested to follow the suite.

B) Till the SMS is implemented in MSETCL, MSETCL Nagpur Circle may adopt a time delay of 100msec for high and low voltage triggering of DRs.

iv) The Committee expresses its concern that 400kV Padghe substation does not have compatible device to download the disturbance data recorded from the memory of the numerical distance relays installed on 400kV lines. The Committee recommends that every sub-station having numerical relays be provided with compatible data downloading device to facilitate analysis of the vital information.

Protection Committee stressed the

importance of compatible data

download facility and requested

constituents to arrange for same

expediously.

MSETCL

informed that data

down loading

facility from

numerical relays

has been included

in their Substation

Monitoring

Schemes (SMS)

and would be made

available by

Nov.08. Vashi,


Nasik and Nagpur

Circles of

MSETCL had

provided laptops at

all the S/s for

downloading the

data. GETCO has

confirmed that data

down loading

facility has been

made available at

all the S/s.

PowerGrid has

confirmed that data

downloading

facility is available

at all the S/s.

All other

constituents were

requested to follow

suite and intimate

the progress.

CSEB informed that this recommendation is in process of implementation and will be complied by Dec.08. MPPTCL informed that this facility has been included in ERPC


(Enterprising Resource Planning Scheme), which is under tendering process.

v) The simulation studies indicate that the distance protection scheme provided on some lines are under-reaching due to in-feed effect. Protection Committee of WRPC may look into this aspect and review the settings of 400 kV lines considering in-feed.

In 98th PCM it was agreed that Zone –III settings considering in-feed effect is to be arrived after due study and on case to case basis. It was suggested that each state should initiate studies starting with any one station in their system results of the study may be put up to Committee for further discussions.

MSETCL informed that protection review group has been formed and the group will take up this issue as a part of their study activity. Constituents are once again requested to carryout study for one of the 400kV S/S in their system and put up to committee for further review. MSETCL was requested to pursue with the protection review group to take up the issue for Padghe S/S.

vi) Since the 400 kV Chandrapur-Parli T/c is a very important corridor for power flow, the relays on this line should be replaced at the earliest by latest type of numerical relays. Meanwhile the feature of lenticular characteristics available in micromho relay may be used as an interim measure instead of circular characteristics feature being presently used.

MSETCL has confirmed that all the three feeders of 400 kV Chandrapur – Parli are fitted with numerical Areva make Micom- P 44 2 relays at both ends as main-I and main-II protection and the recommendation


has been complied.

vii) With the tripping of ± 500 kV Chandrapur-Padghe HVDC link, large quantum of power gets suddenly diverted to other alternative A.C. networks and usually results in tripping of a number of lines on power swings. The Committee recommends that with the tripping of the both poles of HVDC link, generation level at Chandrapur thermal power station of MSPGCL may be brought down automatically to prevent spread of the disturbance. WRPC may work out a suitable scheme in consultation with MSETCL

MAHAGENCO/MAHATRANSCO were requested to expedite action to formulate the scheme.

Representative of MAHAGENCO informed that the matter is still in discussion stage at H.O. Mumbai and MAHAGENCO will inform the committee about any development. Protection Committee requested MAHAGENCO to expedite the action.

viii) In the grid disturbance of 25th February, 2007, the ER-NR inter tie got tripped resulting in disconnection of NR grid from ER grid. Subsequently, some more inter-regional links between ER/NR and NR/WR have been added which may help in reducing the impact of a disturbance in a Region on other Regions operating in parallel. However, the committee is of the view that special protection scheme be worked out on priority and implemented between the various Regions operating in interconnected mode so as to minimize the impact of a disturbance in a region on

Matter regarding formulation of special protection scheme to avoid disturbance due to occurrence in other region has been referred to CEA New Delhi for further action. WRLDC informed that they are in process of carrying out studies in order to devise special protection schemes in the event of tripping of regional links. As NR, WR, ER and NER are


other regions. interconnected with many 400kV and 220kV links, a composite study is required to arrive at SPS in connection with regional links. The results of the studies carried out by WRLDC will be put up to the Protection Committee for further action.

baart sarkar government of india kond`iya ivavut p`aiqakrna · 2009-01-02 · natural environment...

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