baart sarkar government of india kond`iya ivavut p`aiqakrna · 2009-01-02 · natural environment...
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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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¨¸ì �¸¾“ˆÅ ˆÅ¸ ˆÅ¸¡¸Ä¨¸¼î¸— Sub :- Minutes of 103rd Protection Committee Meeting held on 12th & 13th December 2008 at
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.
¤¸¾“ˆÅ ˆÅ¸ ˆÅ¸¡¸Ä¨¸¼î¸ œ¸®¸½¢¨¸ ¬¸¢Ÿ¸¢÷¸ ˆÅú ¨¸½¤¸¬¸¸ƒ’ www.wrpc.gov.in œ¸£ ž¸ú „œ¸¥¸¤š¸ í¾ — Minutes are also available at WRP Committee website www.wrpc.gov.in
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.
Minutes of 103rd WRPC PCM
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.
Minutes of 103rd WRPC PCM
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.
Minutes of 103rd WRPC PCM
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
Minutes of 103rd WRPC PCM
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
Minutes of 103rd WRPC PCM
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
Minutes of 103rd WRPC PCM
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.
Minutes of 103rd WRPC PCM
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.
Minutes of 103rd WRPC PCM
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.
Minutes of 103rd WRPC PCM
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.
Minutes of 103rd WRPC PCM
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.
Minutes of 103rd WRPC PCM
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.
Minutes of 103rd WRPC PCM
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
Minutes of 103rd WRPC PCM
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
Minutes of 103rd WRPC PCM
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
Minutes of 103rd WRPC PCM
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.
Minutes of 103rd WRPC PCM
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.
Minutes of 103rd WRPC PCM
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
Minutes of 103rd WRPC PCM
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)
Minutes of 103rd WRPC PCM
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.
Minutes of 103rd WRPC PCM
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.
3.15 400 KV Kasor 400 KV Kasor-GPEC
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
3.16 400 KV Kasor 400 KV Kasor-SSP
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
3.18 400kV Vindhyachal
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
3.23 400kV Vindhyachal
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.
Minutes of 103rd WRPC PCM
3.27 400kV Vindhyachal
400kV V'chal-Jabalpur Ckt.III
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)
3.28 400kV Vindhyachal
400kV V'chal-Jabalpur Ckt.IV
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
400kV Raipur-Bhadrawati 2
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
400kV Raipur-Bhadrawati 1
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.
Minutes of 103rd WRPC PCM
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.
3.40 400 KV Chorania
400 KV Chorania-Asoj
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.
3.42 400 KV Chorania
400 KV Chorania-Asoj
GETCO Y 25.08.08 23:34 25.08.08 23:43 A/R lockout at both end. No
fault found.
3.43 400kV Vindhyachal
400kV V'chal-Jabalpur Ckt.IV
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)
3.45 400kV Vindhyachal
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)
3.46 400kV Vindhyachal
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
400kV Raipur-Bhadrawati 3
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
3.49 400kV Satna 400kV Satna-Bina Ckt.II
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
400kV Tarapur -Padghe 1
PowerGrid 04.09.08 15:26 04.09.08 16:14 Line tripped on R-E fault (F/L 40.5km from Tarapur)
Minutes of 103rd WRPC PCM
3.52 400kV Satna 400kV Satna-Bina Ckt.II
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.
3.53 400kV Satna 400kV Satna-Bina Ckt.II
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.
3.56 400V Raigarh 400V Raigarh-Rourkela 1
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.
3.58 400kV Vindhyachal
400kV V'chal-Jabalpur Ckt.III
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
400kV Tarapur -Padghe 1
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.
3.61 400 KV Kasor 400 KV Kasor-GPEC
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
Minutes of 103rd WRPC PCM
3.64 400V Raigarh 400V Raigarh-Rourkela 1
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.
3.66 400 KV Kasor 400 KV Kasor-SSP
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
3.74 400 KV Kasor 400 KV Kasor-SSP
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
Minutes of 103rd WRPC PCM
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
Minutes of 103rd WRPC PCM
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
Minutes of 103rd WRPC PCM
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,
Minutes of 103rd WRPC PCM
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
Minutes of 103rd WRPC PCM
(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
Minutes of 103rd WRPC PCM
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
Minutes of 103rd WRPC PCM
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.