nrldc agenda for 27th psc - · pdf fileat parichha tps, distance protection relay of 220 kv...

Northern Regional Power Committee

Supplementary Agenda for 27th PSC meeting A.2 Tripping events to be discussed in details

a. Multiple element tripping at 400 kV Muradnagar(UP) on 17th May 2014 at 21:31hrs Event category: GD-1 Generation loss: Nil Loss of load: 650MW(UP may confirm)

As reported, R-phase jumper of 220kV Muradnagar-Baraut line snapped. Due to delayed clearance of fault all 3 ICT’s at 400/220kV Muradnagar station tripped. 400kV Dadri-Muradnagar line also tripped from Muradnagar end.

As per PMU & SCADA data:

1. Fault Clearing Time: 1000ms 2. Max dip in Red-phase. 3. 220kV Baraut-Muradnagar line tripped from Baraut end at 21:31:53.223hrs & after

~1129ms at 21:31:54.349hrs 400/220kV ICT-2 at Muradnagar tripped from 400kV side.

4. At 21:31:54.369hrs ICT-3 at 400/220kV Muradnagar tripped & at 21:31:54.418hrs 400/220kV ICT-1 at Muradnagar tripped.

Inferences & Points require more clarity in understanding the tripping (As per NRLDC)-

1. Fault was in 220kV Muradnagar-Baraut line and didn’t clear from Muradnagar end. Line tripped from Baraut end

2. 220kV Sahibabad-Muradnagar D/C also tripped from Sahibabad end but on which protection needs to be looked into.

3. 400kV Dadri-Muradnagar line tripped from Muradnagar end in Zone-4 protection. It was also confirmed from Dadri telephonically that same line didn’t trip from Dadri end. PLCC link in this line needs to be looked into.

4. 400/220kV ICT’s tripped on directional over current protection due to delayed clearance of fault.

5. Although all the 220kV lines from Muradnagar end didn’t trip but as load is radially connected and after tripping of all 3ICT’s there was no source of feeding the fault i.e. fault get cleared. Later on remaining ckts were manually opened.

Preliminary Report, Detailed report along with DR/EL has not been received from UP.

UP may elaborate the incident and submit the analysis report to NRLDC/NRPC and may also apprise the members about corrective actions already taken/being taken (within time line) to avoid such events.

b. Multiple element tripping at 400 kV Moradabad(UP) on 18th May 2014 at 10:13hrs

& 22nd May 2014 at 10:05hrs Event category: GD-1 Generation loss: Nil Loss of load: 550MW (As per UP report)

It has been reported that on 22nd May 2014 at 10:05hrs, both 400/220kV, 315MVA ICT #1 & #2 at Moradabad station reportedly tripped on Overloading causing complete supply failure at 220kV end. ICT-2 tripped on overload followed by tripping of ICT-1 on directional overcurrent.


1. From PMU, no fault is observed. 2. From SoE, it seems that there is a difference of ~5sec between tripping of 400kV

side & 220kV side breaker of both the ICTs. Upon asking, it was reported that due to connection problem the digital signal of 400kV side CB of ICT-2 & ICT-1 interchanged. The problem was rectified thereafter.

3. It seems that 220kV Khurja-Sikandrabad and 132kV Khurja-Debai tripped/opened just before the tripping of ICTs.

4. From SCADA data, it is observed that the flow on both the ICTs was ~305MVA, less than the rating of ICTs (315MVA).

Points requires more clarity in understanding the tripping (As per NRLDC)-

1. The difference in timing of ~5sec in tripping of both the ICTs need to be relooked. 2. The settings of the ICT viz. overload, instantaneous overcurrent, directional

overcurrent to be reviewed and shared. 3. The actual cause of sudden overloading of the ICTs to be ascertained and

measures to arrest the same to be looked into. 4. The tripping of 220kV Khurja-Sikandrabad and 132kV Khurja-Debai to be

confirmed. 5. UP needs to expedite one more ICT at Moradabad station because at present it is

not N-1 secure.

Remedial Action to be Taken (As per UP Report)-

1. At 400 KV Moradabad S/S, the load on 2x315 MVA transformers be monitored and controlled by the sub-station by opening 132 KV radial feeders by rotation so as to prevent tripping on overloading. (Action UPPTCL)

Note: Similar kind of incidence also took place on 18-May-2014 at 10:13hrs also.

Preliminary Report & Detailed report have been received from UP. DR/EL has not been received.

UP may elaborate the incident and may also apprise the members about corrective actions already taken/being taken (within time line) to avoid such events.

c. Multiple element tripping at 400 kV Chamera-II HEP(NHPC) on 22nd May 2014 at

21:36hrs Event category: GD-1 Generation loss: 100MW Loss of load: Nil (J&K may confirm)

It has been reported that on 22nd May 2014 at 21:36hrs,400kV Kishenpur-Chamera-II line tripped on Blue phase to ground fault in zone-1 from Chamera-II end. GT of unit-2 of Chamera-II tripped on over current protection.


1. Fault clearing time~80ms. Fault is observed twice in B-phase. 2. Maximum voltage dip is in B-phase. 3. It seems from PMU data that line auto reclosed successfully but later on 3-phase

tripping occurred on fault due to reoccurrence of fault in breaker reclaim time (25 second).

DR/EL has been received from Chamera-II station. It was observed that Line DR of Kishenpur end & unit DR of Chamera-II station are not time synchronized.


1. In pre fault condition current of blue phase of 400kV Kishenpur-Chamera-II ckt needs to be looked into.

2. Instantaneous tripping of GT of unit-2 needs to be looked into as fault cleared within 80ms.

3. Time synchronization of DR of Chamera-II end & Kishenpur(PG) end needs to be ensured.

Preliminary Report & DR/EL have been received from Chamera-II. DR/EL from POWERGRID and Detailed report from Chamera-II have not been received.

POWERGRID/NHPC may elaborate the incident and submit the analysis report to NRLDC/NRPC and may also apprise the members about corrective actions already taken/being taken (within time line) to avoid such events.

d. Multiple element tripping at 400kV Lucknow(UP) on 23rd May 2014 at 15:48hrs

Event category: GD-1 Loss of load: 750MW (As per UP Report) Generation Loss: Nil

Antecedent condition (as reported):

220 KV Lucknow (U.P.) – Unnao ckt –I tripped at 11:33 hrs. on R-phase to earth fault. Under break down.

220 KV Lucknow (U.P.) – Unnao ckt –II was under shutdown w.e.f. 11:18 hrs.

220 KV Unchahar TPS – Rai Bareilly (PG) ckt- I, II & III were under break down.

As reported, 220 KV Rai Bareilly (PG) was in radial mode due to break down of Unchahar-Rai Bareilly-I, II & III and was drawing around 60 MW from 220 KV Chinhat and 400/220 KV Lucknow(UP) each. Due to above import of power by Rai Bareilly (PG) both ICTs at Lucknow(UP) and 220 KV Lucknow (PG)-Chinhat lines were overloaded. At 15:48 hrs, 400/220 KV, 240 MVA ICT-I & II tripped on overload and finally entire supply of Lucknow area failed due to tripping of 220 KV Lucknow (PG)-Chinhat line.

As per PMU and SCADA data:

No fault is observed in PMU.

SoE is not configured at NRLDC.

From SCADA data, it is observed that the flow on both the ICTs was ~240MW & 232MW respectively. 220kV Lucknow-Chinhat line was overloaded upto ~374MW.

Points require more clarity in understanding the tripping (As per NRLDC)-

The overload setting of the ICT needs to be reviewed and shared.

Remedial Action to be taken (As per UP report)-

At 400 KV S/S Lucknow (U.P.), overloading of 2x240 MVA ICTs be controlled by the Sub-station at their end by opening of 132 KV radial feeders by rotation. (Action UPPTCL).

Preliminary Report & Detailed report have been received from UP.

UP may elaborate the incident and may also apprise the members about the corrective actions already taken/being taken (with time line) to avoid such incidents in future.

e. Multiple element tripping at 400 kV Sonepat(PG) on 23rd May 2014 at 16:18hrs Event category: GD-1 Generation loss: Nil Loss of load: 250MW (Haryana may confirm) As reported, Y-phase conductor of 220kV Sonepat-Mohana ckt-1 snapped and flash over took place at Tower no.1. Due to delayed clearance of fault 220kV Sonepat-Mohana ckt-2 and all 2 ICT’s at 400/220kV Sonepat station also tripped.


1. Fault Clearing Time was ~1320ms with max dip in Yellow-phase.

Fault was in 220kV Sonepat-Mohana line and didn’t clear from Mohana end. 400/220kV ICT’s tripped on directional over current protection due to delayed clearance of fault. Points requires more clarity in understanding the tripping (As per NRLDC)-

1. Non-clearance of fault from Mohana end need to be looked into.

Preliminary information has been received from Sonepat (PG). Preliminary Report, Detailed Report along with DR/EL has not been received from POWERGRID/Haryana.

POWERGRID/Haryana may elaborate the incident and submit the analysis report to NRLDC/NRPC and may also apprise the members about corrective actions already taken/being taken (within time line) to avoid such events.

f. Multiple element tripping at 400 kV Parichha(UP) on 29th May 2014 at 13:19hrs Event category: GD-1 Generation loss: 843MW (As per UP report) Loss of load: Nil

It has been reported by Parichha TPS and UPPTCL site that an R-phase fault took place on 220 kV Parichha-Orai-I line. At Orai S/S, circuit breaker tripped but at Parichha TPS, D.P. Relay did not operate. At Parichha TPS, 220 KV Bus Bar Protection is out of service. This resulted in tripping of 220 KV Parichha-Orai-III line at Orai S/S and tripping of Parichha Unit Nos. III, IV, V & VI due to loss/tripping of 6.6 KV station supply on account of low voltage. 220 KV Parichha-Banda line tripped at Parichha S/S on L.B.B. protection.

Flag details(As reported):

1. 220kV Parichha-Orai-I: C/P- DPO, R/P- GT, R-phase to ground, Zone-1, Pick up time= 760ms, trip time= 100ms, IR= 1.89kA, IY= 0.18kA, IB= 0.22kA, FLR= 52.9km or 47.2%.

2. 220kV Parichha-Orai-III: C/P- DPO, R/P- GT, R-Y-phase to ground, Zone-5(reverse zone), Pick up time= 2064ms, trip time= 2000ms, IR= 1.04kA, IY= 0.82kA, IB= 0.38kA, FLR= 182km or 175%.

3. 400/220kV, 315MVA ICT-1&2 tripped on definite time earth fault relay with time setting 1.2sec and current 0.28 times of normal value.


1. It seems that fault get cleared after so much time~4000ms. 2. It seems from PMU data that max dip was in R-phase. 3. Digital data (SoE) was not available.


1. Zone-5 setting for 220kV Orai-Parichha ckt-3 is 2000ms. Reason behind too much high setting needs to be relooked.

2. Distance protection did not operate at Parichha TPS, it needs to be relooked. 3. 220kV Parichha-Banda did not tripped from Banda it seems Carrier

communication failure. 4. Non-tripping of 220 KV Parichha-Bhartana and 220/132kV ICT-1&2 needs further

investigation. 5. Tripping of GT-3, 4, 5&6 needs to be relooked; either tripped due to failure of

auxiliary supply or protection operated.


1. At Parichha TPS, distance protection relay of 220 KV Parichha-Orai-I line be attended and set right for correct tripping under fault conditions (Action Parichha TPS, UPRVUNL).

2. At Parichha TPS, 220 KV Bus Bar protection be put back in service at the earliest (Action Parichha TPS, UPRVUNL).

3. At Parichha TPS, tripping of 220 KV Parichha-Banda line for a fault in the reverse direction, be investigated and set right (Action Parichha TPS, UPRVUNL).

4. Non-tripping of 220 KV Parichha-Bhartana line needs further investigation (Action Parichha TPS, UPRVUNL/UPPTCL).

5. At Parichha TPS, it has been observed several times in the past, that delayed/non-clearance of line faults from Parichha TPS end has resulted in complete tripping of all the generating units and lines. It seems that protection system of the transmission lines is not effective at Parichha end. Therefore, at parichha TPS, the polarity of all the instrument transformers and their star points be checked and setting and periodical testing of all the line protections be ensured so as to avoid tripping of generating units. (Action Parichha TPS, UPRVUNL).

Preliminary Report & Detailed report have been received from UP. It was also reported that Printouts of disturbance recorder/event logger were not available.


g. Multiple element tripping at 400 kV Agra(UP) on 05th June 2014 at 23:56hrs Event category: GD-1 Generation loss: Nil Loss of load: 1059MW (As per UP report) It was informed by UPPTCL site, that at 400kV Agra UP S/S, R-phase C.T. of 220kV side of 400/220kV 315MVA ICT-I failed. At the same time 400/220kV 315MVA ICT-2 tripped on differential protection, 400/220kV ICT-2, 500MVA ICT-1 tripped in cascading on overcurrent protection. 220kV side bus bar differential protection at Agra (UP) is not available. Sequence of tripping is mentioned below:

1. 400/220kV 315MVA ICT-1 tripped on differential protection operation

2. There was cascading impact on other ICT’s at 400/220kV Agra (UP). 3. 400/220kV 315MVA ICT-2 tripped on directional over current & earth fault

protection. 4. 400/220kV 500MVA ICT tripped on backup overcurrent protection 5. 220kV Agra (UP)-Gokul ckt also tripped (as per NR SoE).


1. Fault was in R-phase & fault clearing time was ~80ms. 2. As per SCADA data it seems 400/220kV ICT-1 tripped and after some time

400/220kV 315MVA ICT-2 & 400/220kV 500MVA ICT tripped. It was also observed that power flow on 400kV Agra(PG)-Agra(UP) ckt also became zero at the time of tripping of all the ICT’s.

3. From SoE & sample SoE data of ICTs, either the 400kV side or 220kV side of ICT-1&2 sees interchanged.


1. Healthiness of Bus Bar Protection at 220kV side of Agra (UP) station needs to be looked into.

2. Cascading tripping of ICT’s at Agra (UP) needs to be looked into. 3. ICT’s at Agra (UP) seems not to be N-1 secure. 4. Over current & earth fault setting of all 3 ICT’s needs to be reviewed & shared. 5. Reason of zero power flow over 400kV Agra (PG)-Agra (UP) lines need to be

looked into. 6. Digital data of Agra (UP) needs to be reviewed & corrected. 7. SoE status of the ICTs to be checked for possible interchange of 400kV/220kV

side of ICT-1&2. 8. ICT’s at Agra (UP) don’t have numerical relay. Retrofitting of old relay needs to be

expedited. 9. In case of blast in CT, C & tan delta test of nearby instrument is always advisable.


1. At 400 KV Agra S/S, Dielectric strength of oil of all the Instrument Transformers be checked. (Action UPPTCL)

Remedial Action to be Taken (As per NRLDC)-


2. Special Protection Scheme of ICT’s at Agra (UP) needs to be expedited to prevent cascade tripping of the ICT’s.

Detailed report has been received from UP. It was it was mentioned in the report that DR printout was not available.


h. Multiple element tripping at 400 kV Chhabra TPS (Rajasthan) on 05th June 2014 at

13:10hrs Event category: GD-1 Generation loss: 460MW (Rajasthan may confirm) Loss of load: 165MW (Rajasthan may confirm) As per Rajasthan reported and telephonic conversation, 400KV CTPP-Bhilwara Feeder tripped at 13.10:24:646hrs on dated 05.06.2014 with fault indication zone-2 R-Phase distance 346 km. On inquiring from 400 KV Bhilwara it is known that 220 KV feeder fault reflected. The relay setting for zone-2 is 120% of total distance with time delay 300ms. The feeder from remote End tripped on DT received on account of overvoltage, as the fault in their end in reverse zone. Unit-1&3 were running on Bus-1. Due to tripping of 400KV CTPP-Bhilwara the running Unit–I tripped under SPS protection. Unit-2 was already shutdown so that due to opening of breaker 402 & 405, both Buses had become isolated and leading to power evacuation problem for unit-3. Now Unit-3 was connected only with 400/220kV ICT. Unit-3 was running at 230MW and load on 315 MVA, 400/220 KV ICT was 165MW resulted into tripping of Unit –3 tripped on over voltage stage-1.


2. As per PMU max. Voltage dip is in B-phase, while reported in R-phase. 3. Fault clearance time~ 560ms. 4. No SoE, w.r.t. the tripping, reported at NRLDC.


2. From which 220kV feeder from which fault was reportedly reflected to be looked into.

3. As per PMU & reported time of tripping, it seems time is not synchronized. 4. Fault location need to be relooked. 5. Non opening of CB at Bhilwara end in zone-1 need to be relooked. 6. Digital SCADA data reporting to be reviewed.

Detailed Report along with Event log(EL) has been received from Rajasthan while DR has not been received.

Rajasthan may elaborate the incident and may also apprise the members about corrective actions already taken/being taken (within time line) to avoid such events.

i. Complete station outage of 400 kV Khedar TPS(Haryana) on 05th June 2014 at

00:03hrs Event category: GD-1 Generation loss: 580MW (Haryana may confirm) Loss of load: Nil (As per Haryana report)

As reported, B-ph CT of Bus coupler towards Main Bus-1 at Khedar bursted & resulted into Bus Bar Protection operation for Main Bus-1. At the same time Bus Bar Protection for Main Bus-2 also operated and resulted into complete outage of the 400kV Khedar generating station.


1. Three incidents of fault & Fault got clear within time limit of zone-1 for first two incidents. In third incident fault clearing time was ~360ms.

2. Initial fault was in Blue phase. It’s the time of operation of Bus Bar Protection on Bus-1.

3. As per NR SoE, at 00:03:00.680hrs Fatehabad-Nuhianwali ckt tripped from Fatehabad end. Fault got cleared within 100ms (R-phase to ground fault). Later on at 00:03:01.480hrs again fault occurred in initially in Y-phase and then in R-phase. Fault clearance time was ~360ms; however as per NR SoE Fatehabad-Nuhianwali ckt again tripped at the time of clearing of fault.

Inferences & Points requires more clarity in understanding the tripping (As per NRLDC)-

1. Operation of Bus Bar Protection for Bus-II needs to be looked into. 2. Tripping of 400kV Fatehabad-Nuhianwali was not informed by Haryana. 3. As per flag details received from Haryana, tripping of 400kV Fatehabad-Khedar ckt

from Fatehabad end needs to be looked into. 4. Running of GT-2 & ST-2 with unit-2 under shutdown, needs more clarity from

Haryana. 5. In SoE reported by Haryana, Hissar was mentioned instead of Khedar. 6. Wiring of digital data & availability of analog data of Khedar station needs to be

ensured.

Preliminary report along with DR/EL has been received from Haryana. Detailed report is yet to be received from Haryana.

Haryana may elaborate the incident and submit the analysis report to NRLDC/NRPC and may also apprise the members about corrective actions already taken/being taken (within time line) to avoid such events.

j. Multiple element tripping at 400 kV Moradabad(UP) on 06th June 2014 at 11:50hrs Event category: GD-1 Generation loss: Nil Loss of load: 400MW (As per UP report)

It was reported that at 11:50 hrs. at 400 KV S/S Moradabad, Y-phase to ground fault took place on 220 KV Moradabad-CB Ganj line. At CB Ganj S/S, circuit breaker tripped but at Moradabad S/S distance protection relay and backup protection did not operate. 220 kV Bus Bar Protection has been installed but not been commissioned. The fault was finally isolated by tripping of all the remaining two nos. lines at remote ends and tripping of 2*315 MVA ICT-I & II from H.V. side. Thus complete 220 KV supply failed at Moradabad S/S.

Bus Bar protection operated for Bus-1 at Ballabgarh(PG). As Dia of 400kV Ballabgarh-Mainpuri ckt-I was incomplete, there is two breaker one is connected to Bus-II & other is tie

CB and connected to Bus-I (As highlighted in the diagram). As Main CB of Bus-II of 400kV Ballabgarh- Mainpuri ckt-1 was already in shutdown, therefore, above operation resulted in tripping of 400kV Ballabgarh- Mainpuri ckt-1.

As reported by Bamnauli, 400kV Ballabgarh- Bamnauli both circuits tripped from Bamnauli end on receiving of 85LO which means DT received at Bamnauli end.

As per DR details fault current was ~46kA.


1. From PMU, it seems that fault persisted till~ 2440ms. As per flag detail fault was in 220kV Moradabad-CB Ganj line and cleared in Zone-1, FLR= 62km. But continuously fed from Moradabad.


1. CB of 220kV Moradabad- CB Ganj didn’t operated at Moradabad end, it seems distance protection failure it needs to be relooked.

2. Backup protection also needs to be checked again with its sensitivity settings. 3. Availability of Carrier communication at CB Ganj S/S must be ensure. If it is then it

needs to be rechecked again. 4. Persistent of fault for such long time duration needs to be looked into.

Remedial Measures to be Taken (As per UP Report)-

1. At Moradabad S/S, the line distance protection relay and backup protection of 220 KV CB Ganj line be checked and put back into service at the earliest.

2. At Moradabad S/S, the 220 KV Bus Bar system be commissioned and put in service at the earliest.

Preliminary Report & Detailed report have been received from UP. As reported by UP, Print out of disturbance recorder & Event recorder are not available.


k. Multiple element tripping at 400 kV Daultabad(Haryana) on 07th June 2014 at

15:37hrs Event category: GD-1 Generation loss: Nil Loss of load: 600MW (Haryana may confirm)

It has been reported that on 07th June 2014, at 15:06hrs, 400/220kV ICT-2 at Daultabad station tripped on PRV (Pressure Release Valve). Later on at 15:37hrs 400/220kV one ICT at Daultabad also tripped on PRV and remaining ICT tripped on over load and at the same time 400kV Daultabad-Gurgaon ckt1 & Daultabad-Jhajjar(APCPL) ckt1 also tripped because both the line charged through tie CB only (as problem in CT of main CB.

As per PMU data:

1. At 15:37:16.360hrs voltage dip in R & Y-phase has been observed, lasted for 80ms.

2. At 15:37:55.760hrs Voltage dip in Y-phase has been observed, lasted for 400ms. 3. At 15:37:58.800hrs Voltage dip in R-phase has been observed, lasted for 80ms.


1. Wiring of digital data needs to be looked into. 2. Voltage dips at three instants to be looked into.

Preliminary Report, Detailed report along with DR/EL has not been received from Haryana/APCPL/POWERGRID.

Haryana/APCPL/POWERGRID may elaborate the incident and submit the analysis report to NRLDC/NRPC and may also apprise the members about corrective actions already taken/being taken (within time line) to avoid such events.

l. Multiple element tripping at 400 kV Chamera-II HEP(NHPC) on 08th June 2014 at

16:46hrs Event category: GD-1 Generation loss: 200MW (NHPC may confirm) Loss of load: Nil (J&K may confirm)

It has been reported that on 08th June 2014 at 16:46hrs, unit-1&3 at Chamera-II station tripped due to problem in the optical fibre cable.

As per PMU data:

4. No fault was observed.


4. Wiring of digital data needs to be looked into. 5. Exact cause of tripping of both the units to be ascertained.

Preliminary Report, Detailed report & DR/EL have not been received from NHPC.

NHPC may elaborate the incident and submit the analysis report to NRLDC/NRPC and may also apprise the members about corrective actions already taken/being taken (within time line) to avoid such events.

m. Multiple element tripping at 400 kV Agra(UP) on 09th June 2014 at 20:36hrs Event category: GD-1 Generation loss: Nil Loss of load: 974MW (As per UP report) It was informed by UPPTCL site, that at 400kV Agra UP S/S, B-phase C.T. of 220kV side of 400/220kV 315MVA ICT-2 failed. At the same time 400/220kV 315MVA ICT-2 tripped

on differential protection, 400/220kV ICT-1, 400/220kV 500MVA ICT tripped in cascading on overcurrent protection. 220kV side bus bar differential protection at Agra (UP) is not available. Sequence of tripping is mentioned below:

1. 400/220kV 315MVA ICT-2 tripped on differential protection operation. LBB operated flag also observed.

2. 400/220kV 315MVA ICT-1 tripped on directional over current & earth fault protection.

3. 400/220kV 500MVA ICT tripped on PRV(Pressure Release Valve) protection 4. 220kV Agra(UP)-Sikandra & Agra(UP)-Hathras ckt also tripped later on.


1. 2 instances of fault. Fault cleared in time for first incident but in second time fault clearing time was ~880ms.

2. Max dip in B-phase in first incident & in R-phase in second incident. 3. As per SCADA data it seems 400/220kV 315MVA ICT-1 & 500MVA ICT tripped at

the time of second incident when fault was in Red-phase. 4. From SoE & sample SoE data of ICTs, either the 400kV side or 220kV side of ICT-

1&2 sees interchanged. 5. It seems from SCADA data that flow on 400kV Agra(UP)-Muradnagar became

zero at the time of tripping of ICTs.



2. Cascading tripping of ICT’s at Agra (UP) needs to be looked into. 3. ICT’s at Agra (UP) seems not to be N-1 secure. 4. Over current & earth fault setting of all 3 ICT’s needs to be reviewed & shared. 5. Reason of zero power flow over 400kV Agra (PG)-Agra (UP) lines need to be

looked into. 6. Tripping of 220kV Agra(UP)-Agra(Sikandra)-1, 220kV Agra-Hathras & 400kV

Agra(UP)-Muradnagar to be looked into. 7. It seems from flag details that 500MVA ICT tripped on PRV trip, the same to be

relooked. 8. SoE status of the ICTs to be checked for possible interchange of 400kV/220kV


expedited. 10. In case of blast in CT, C & tan delta test of nearby instrument is always advisable.



Remedial Action to be Taken (As per NRLDC)-

1. Special Protection Scheme of ICT’s at Agra (UP) needs to be expedited to prevent cascade tripping of the ICT’s.

2. It was reported that both Agra(PG)-Agra(UP) ckt’s are on same bus. It must be on different bus for good operational practices.



n. Multiple element tripping at 400 kV Karcham Wangtoo(JPVL) on 11th June 2014 at 16:52hrs

Event category: GD-1 Generation loss: MW (JPVL may confirm) Loss of load: Nil

It was reported that at 16:52hrs of 11th June 2014, Y-phase to earth fault occurred in 400kV Karcham to Abdullapur ckt-2, at the same time 400kV Karcham-Baspa ckt1 & 2 also tripped from Baspa end in zone-2. 400kV Karcham to Abdullapur ckt-2 line auto reclosed and finally tripped due to persistence of fault.

At 17:14hrs, during charging of 400kV Karcham-Abdullapur ckt-2, This line tripped on SOTF and 400kV Karcham-Baspa ckt1 & 2 also tripped from Baspa end in zone-2.

As per PMU data & DR:

4. It seems from PMU & DR data that there were three instances of fault at 16:52hrs & max dip in Yellow-phase. Second dip indicates unsuccessful auto reclosing although it seems that remaining two phases(R&B) opened at third instance of Voltage dip.

5. At 17:14hrs again Y-phase to ground fault observed in PMU data. 6. Fault clearing time for all the instances was within 100ms.


6. Tripping of 400kV Baspa-Karcham ckt-1 & 2 at 16:52hrs & 17:14hrs needs to be looked into.

7. Better patrolling practice for line have persistent fault to be used. For example in this case: 400kV Karcham-Abdullapur ckt-2.

8. Utilities to ensure that .dat & .cfg files of DR/EL with complete naming (which breaker, which element, of which end) to be submitted for better understanding of the tripping.

Preliminary Report, Flag details and DR/EL have been received from Karcham but Detailed Report is still awaited. DR/EL from Baspa & POWERGRID is also yet to be received. Remedial action already taken and to be taken is still awaited from JPVL/ POWERGRID.

JPVL/POWERGRID may elaborate the incident and submit the analysis report to NRLDC/NRPC and may also apprise the members about corrective actions already taken/being taken (within time line) to avoid such events.

o. Multiple element tripping at 400 kV Agra(UP) on 11th June 2014 at 14:41hrs Event category: GD-1 Generation loss: Nil Loss of load: 800MW (As per UP report) It was informed by UPPTCL site, that at 400kV Agra UP S/S, flashover has observed in the B-phase bushing of 400kV side of 400/220kV 500MVA ICT and ICT tripped on differential protection operation. After some time 400/220kV 315MVA ICT-1 & 2, tripped in cascading on overcurrent protection.

Flag Details received from UP:


1. At 14:40:59.880hrs B-phase to ground fault occurred in 500MVA ICT. 2. At 14:41:04.720hrs remaining two ICTs of Agra(UP) tripped. It resulted into rise in

the frequency.



2. Cascading tripping of ICT’s at Agra (UP) needs to be looked into. 3. ICT’s at Agra (UP) seems not to be N-1 secure. 4. Over current & earth fault setting of all 3 ICT’s needs to be reviewed & shared. 5. SoE status of the ICTs to be checked for possible interchange of 400kV/220kV


expedited.


UP may elaborate the incident and may also apprise the members about corrective actions already taken/being taken (within time line) to avoid such frequent tripping.

p. Multiple element tripping at 400 kV Gurgaon(PG) on 12th June 2014 at 14:24hrs Event category: GD-1 Generation loss: Nil Loss of load: 100MW (Haryana may confirm)

It has been reported that on 12th June 2014 at 14:24hrs, 400kV Gurgaon-Bhiwadi & 400kV Gurgaon-Manesar ckt-1 tripped on phase to earth fault.

It seems from PMU data that at 14:24hrs of 12th June 2014, 400kV Gurgaon-Bhiwadi ckt tripped on B-phase to ground fault. Line auto-reclosed successfully but again fault occurred in the line within reclaim time(25second) and the same line finally tripped all 3-phase. 400kV Gurgaon-Mansar ckt-1 also tripped.

As per PMU data:

1. It seems from PMU data that there were three instances of fault at 14:24:47.123hrs Y-phase to ground fault occurred, line auto reclosed successfully but again at 14:24:49.540hrs fault observed in Y & B-phase. At the same time 400kV Gurgaon-Bhiwadi tripped.

2. At 14:25:11.920hrs B-phase to ground fault observed in PMU data. At the same time 400kV Gurgaon-Manesar ckt-1 tripped

3. Fault clearing time for all the instances was within 100ms.


1. NRLDC SoE timings pertaining to the tripping needs to be ensured by POWERGRID.

2. Tripping of load of 100MW needs to be confirmed by Haryana.

Preliminary Report, Detailed report & DR/EL have not been received from POWERGRID.

POWERGRID may elaborate the incident and submit the analysis report to NRLDC/NRPC and may also apprise the members about corrective actions already taken/being taken (within time line) to avoid such events.

q. Multiple element tripping at 765/400 kV Unnao(UP) on 12th June 2014 at 14:24hrs Event category: GD-1 Generation loss: Nil Loss of load: 820MW (As per UP report)

It was reported by UPPTCL site that at 17:51 hrs on 12.06.2014, repeated R phase to earth fault occurred on 400kV Unnao-Bareilly line II. On first occurrence, the line auto-reclosed from both ends while on next fault, line finally tripped as the fault recurred within reclaim time. However, on both incidents, the line tripped with a time delay of

approximately 150ms due to non-receipt of permissive trip command from Bareilly end (tripping occurred in Z1B instead of Zone 1). At Unnao S/S, Main II relay (REL670) of Bareilly-II line is defective. Also, R-Phase jumper of FSC main bypass switch got damaged in the incident. Simultaneously, 765/400 KV, 1000 MVA ICT-I & II at Unnao also tripped on Breaker over current protection. Name of the tripping elements are given below:

SI. NO.

Name of element Date & time of normalization

Remarks

1. 765/400 KV, 1000 MVA ICT-I at Unnao

12.06.2014 19:28 Tripped on 400 KV side

2. 765/400 KV, 1000 MVA ICT-II at Unnao

12.06.2014 19:28 Tripped on 400 KV side

3. 400 KV Unnao-Bareilly-II 13.06.2014 16:51 - 4. 400 KV Unnao-Panki line 12.06.2014 19:11 -

As per PMU data fault clearance time is ~200ms and maximum dip is in Red-phase.

Flag details received from UP is tabulated below:


1. Tripping of Unnao-Panki line has been reported in preliminary report but same is not mentioned in the detailed report.

2. Tripping of 765/400kV ICT at Unnao station in 200ms for through fault needs to be looked into

3. Instead of load loss PMU data of frequency is showing dip in the frequency. It require more clarity.

4. LBB initiation in flag details of 765/400kV ICT-1&2 needs to be looked into.


1. At 400 KV S/S Unnao, the cause of non-receipt of permissive trip command from Bareilly end is to be checked and attended. (Action UPPTCL)

2. At 400 KV S/S Unnao, main II distance protection relay (REL670) of 400 KV Unnao-Bareilly line is to be repaired/ replaced on priority. (Action UPPTCL).

Detailed report has been received from UP. DR printout was provided for Unnao station. NRLDC requested all the entities to kindly provide the .dat & .cfg file of disturbance recorder for analysis purpose.

UP may elaborate the incident and may also apprise the members about corrective actions already taken/being taken (within time line) to avoid such events

r. Multiple element tripping at 400 kV Uri-I HEP on 16th June 2014 at 12:22hrs Event category: GD-1 Generation loss: 475MW Loss of load: (J&K may confirm)

At 12:22hrs, R-phase to ground fault occurred in 400kV Uri II (NHPC)-Uri I (NHPC) ckt. Due to delayed opening of breaker at Uri-I end, LBB protection operated at Uri-I end and Send the command to Bus Bar protection of Bus-II. 400kV Uri-I (NHPC)-Wagoora(PG) D/C & All 4 units (120MW each) of Uri-I(NHPC) tripped because all these ckt connected to Bus-2 only. Uri-I S/S is GIS station with double main & single breaker scheme.

It seems from PMU data that fault was in Red phase. Fault clearing time was ~680ms.


1. Operation at Uri-I seems to be unhealthy practice as all the lines & units are connected to Bus-II with both buses coupled through Bus coupler.

2. It may be possible that fault was in zone-2 from Uri-I end & send trip command to Uri-I end breaker after zone-2 timing of 350ms and breaker at Uri-I failed to operate and resulted into operation of LBB protection at Uri-I end. This case corroborated with our PMU timing(~600ms) but in that case PLCC communication in Uri-I to Uri-II line needs to be checked.

3. Availability of digital & analog data at NRLDC needs to be ensured by NHPC.

Detailed report & DR/EL have not been received from POWERGRID/ NHPC.

NHPC/ POWERGRID may elaborate the incident and submit the analysis report to NRLDC/NRPC and may also apprise the members about corrective actions already taken/being taken (within time line) to avoid such events.

s. Complete blackout at 400 kV Parichha on 19th June 2014 at 10:42hrs Event category: GD-1

Generation loss: 668MW Loss of load: 742MW (as per UP report)

In antecedent condition, unit-1 & 2 of Parichha TPS & 400kV Paricha-Mainpuri(PG) D/C were already under shutdown.

It has been reported by Parichha TPS and UPPTCL site that a fault was created in the switchyard of Parichha TPS due to snapping of 132 KV, Y & B phase jumper of CT of 132 KV Mauranipur feeder. At Parichha TPS, Line distance protection relay of 132 KV Mauranipur feeders is defective. Therefore, Backup dir. E/F earth fault relay operated and circuit breaker tripped delayed. The fault was reflected on 220 KV bus. At Parichha TPS, 220 KV Bus-Bar Protection is out of service. This resulted in tripping of 220/132 KV, 100 MVA transformer but 220/132kV, 160MVA transformer, 132 KV side circuit breaker tripped delayed and 220kV side circuit breaker did not trip. Thus the fault was reflected on 220 KV bus at Parichha, which resulted in tripping of 400/220 KV, 315 MVA ICT-I & II. Due to loss of 6.6 KV station supply, Parichha Generating Unit nos. 3, 4, 5 & 6 tripped. Also, 220 KV Orai-I, II & III, Banda & Bhartana lines tripped at Parichha.

Fault clearance time inferred from PMU data is ~1880ms.

Connectivity diagram of Parichha TPS end is given below


1. At Parichha TPS, Line distance protection relay of 132kV Mauranipur line be attended and put in service. (Action Parichha TPS, UPRVUNL)

2. At Parichha TPS, 220 KV Bus Bar protection to be put in service at the earliest. (Action Parichha TPS, UPRVUNL)

3. At Parichha TPS, protection scheme of 220/132 KV, 160 MVA ICT be checked and attended to ensure correct tripping of the ICT during fault conditions. (Action Parichha TPS, UPRVUNL)

4. At Parichha TPS, it has been observed several times in the past, that delayed/non-clearance of line faults from Parichha TPS end has resulted in complete tripping of all the generating units and lines. It seems that protection system of the transmission lines is not effective at Parichha end. Therefore, at Parichha TPS, the polarity of all the instrument transformers and their star points be checked and setting and periodical testing of all the line protections be ensured so as to avoid tripping of generating units. (Action Parichha TPS, UPRVUNL)

Detailed report has been received from UP. DR/EL details are still awaited.

UP may also apprise the members about corrective actions already taken/being taken (within time line) to avoid such events.

t. Multiple element tripping at 400 kV Tehri(THDC) on 22nd June 2014 at 13:36hrs Event category: GD-1 Generation loss: 251MW (As per THDC Report) Loss of load: Nil

As per information received from Koteshwar pool (O&M) team, the shifting of 11kV line was done by some villagers without any supervision by state Dis-com. They cut the pole and the pole fell down resulting in overshooting of 11kV line thus the clearance was decreased and 11kV line come in near contact with 440kV Koteshwar pool(PG)-Tehri D/C. As per telephonic conversation with Tehri(THDC), Unit#2&4 continued to run in isolated mode after tripping of 400kV Koteshwar pool(PG)- Tehri D/C from both ends. No Unit protection was operated and finally units #2&4 was tripped by manually operation

It seems from PMU data that at 14:24hrs of 12th June 2014, 400kV Gurgaon-Bhiwadi ckt tripped on B-phase to ground fault. Line auto-reclosed successfully but again fault occurred in the line within reclaim time(25second) and the same line finally tripped all 3-phase. 400kV Gurgaon-Mansar ckt-1 also tripped.

As per PMU data & DR details:

1. Fault clearing time: ~160ms. 2. Max. voltage dip is in R-phase. Fault was in R-phase. 3. As per DR/EL of Koteshwar pool end, at 13:36:21.919hrs R-phase CB of 400kV

Koteshwar pool(PG)-Tehri ckt1 opened in zone-1 while Y&B-phase CB’s opened at 13:36:22.041hrs.

4. At 13:36:23.040hrs, 400kV Koteshwar pool(PG)-Tehri ckt-2 unsuccesfully auto-reclosed with time delay of1320ms instead of 1000ms.

5. Tehri end Flag of 400kV Koteshwar pool(PG)-THDC ckt-1: Distance trip Z-2, Fault location=14.36 KM, IA=1.704 kA, IB=1.208 kA, IC=917.5 A and Van=34.46kV, Vbn=262.1 kV, Vcn=229.4kV, Fault resistance= 4.086 Ω.

6. Tehri end Flag of 400kV Koteshwar pool(PG)-THDC ckt-2: Distance trip Z-2, Fault location=15.95 KM, IA=1.698 kA, IB=1.034 kA, IC=723.8 A and Van=35.04 kV, Vbn=262.9 kV, Vcn=230.0 kV, Fault resistance= 1.529 Ω


1. As per DR details, it was observed that Y&B phase CB’s of 400kV Koteshwar pool(PG)-Tehri ckt-1 also opened after 122ms, while fault was in only R-phase.

2. Delayed auto reclosing of 400kV Koteshwar(Pooling)-Tehri ckt2 needs to be looked into.

Preliminary Report, Detailed report & DR/EL have been received from POWERGRID/ THDC.

POWERGRID/ THDC may apprise the members about corrective actions already taken/being taken (within time line) to avoid such events.

u. Multiple element tripping at 400 kV Makhu on 28th June 2014 at 17:22hrs Event category: GI-2 or GD-1 Generation loss: Nil Loss of load: (Punjab may confirm)

It was informed by Punjab, that R-phase to ground fault occurred in 400kV Nakodar-Makhu line. This line tripped from Makhu end within 100ms on receipt of carrier from Nakodar end. At the same time Bus Bar Protection for Bus-2 at Makhu mal-operated. It was informed telephonically that breaker status input for one CB was not available to the Bus Bar and it resulted into mal-operation of Bus Bar protection. It was also informed that 400kV Nakodar-Makhu ckt auto-reclosed.

It seems from PMU data that fault clearing time was ~80ms. Fault was in Red-phase. Fault again observed in R-phase after 4200ms. SoE for 400kV Makhu is not configured at NRLDC


1. Healthiness of Bus Bar Protection at 400kV Makhu station needs to be looked into..

2. If line auto-reclosed in 4000ms then same needs to be looked into. (Auto-reclosing time is 1000ms)

3. Wiring of digital data of 400kV Makhu needs to be looked intoPreliminary Report, Detailed report & DR/EL have not been received from POWERGRID.

POWERGRID may elaborate the incident and submit the analysis report to NRLDC/NRPC and may also apprise the members about corrective actions already taken/being taken (within time line) to avoid such events.

v. Multiple element tripping in Delhi(due to Tower Collapse) on 2nd July 2014 at

14:03hrs

Event category: GD-1 Loss of load: 445MW (As per Delhi Report) Generation Loss: 338MW (As per Delhi Report)

Antecedent connectivity (as reported):

GT Station, RPH, Pragati (Unit-2 & STG) were connected to Mandola side through 220kV IP Ext (Pragati) -IP -Patparganj - Geeta Colony -Wazirabad - Mandola Ckts.

Pragati (Unit-I) was connected to BTPS through 220kV Pragati - Sarita Vihar Ckt.-I&II catering the load of Parkstreet Ckts.

As reported, the tripping of 220kV Wazirabad-Geeta Colony Ckt-l& II at Wazirabad & Geeta Colony caused the islanding of generating units at RPH, Pragati (Unit I & STG) & GT running units. The island survived for a while but collapsed due to the tripping of Pragati G.T.

It was further reported that the portion about 8 feet high above the chimney portion of the towers of 220kV Wazirabad-Kashmiri Gate Ckt-l&ll collapsed and rested on 220kV Wazirabad-Geeta Colony Ckt–ll which runs alongside the ckts, causing the damage of two

spans of conductors of 220kV Wazirabad-Geeta Colony Ckt-ll. Flag details at 220kV Wazirabad Station is given below:

Restoration Process:

At 14:16hrs 220kV Bus Coupler closed at 220kV Pragati station and supply extended to G.T., Pragati, RPH & IP Stn for start-up power and to meet important load at RPH & IP Stn. At 14:37hrs 220kV IP-Parparganj Ckt-1 charged from IP Stn. Part load of Kashmiri gate back fed through 33kVCivil Line Ckts at 15:35hrs.

It seems from PMU data that fault was in R-phase followed by B-phase. The fault clearing time was ~800ms.

Points require more clarity in understanding the tripping (As per NRLDC)-

1. Delay in clearance of fault needs to be looked into. 2. Tripping of more than one line in tower collapse. Arrangement to prevent the cascade

tower collapse needs to be discussed.

Preliminary Report has been received from Delhi while Detailed Report along with DRs/EL is still awaited.

Delhi may elaborate the incident and submit the analysis report to NRLDC/NRPC and may also apprise the members about the corrective actions already taken/being taken (with time line) to avoid such incidents in future.

w. Multiple element tripping at 400kV Koteshwar HEP(THDC) on 03rd July 2014 at

22:08hrs

Event category: GD-1 Generation loss: 200MW (THDC may confirm) Loss of load: Nil

Antecedent connectivity (as reported):

Bus Coupler at Koteshwar(THDC) end was under open condition due to some problem of PIR (Pre Insertion Resistor). However, PIR has been replaced later on.

As reported, during shut down of the machine unit CB of R-phase of unit-2 at Koteshwar(THDC), the CB was unable to open due to problem of auxiliary switch of trip circuit. It resulted into operation of LBB (Local Breaker Backup) and sent the trip command to Bus Bar of Bus-1. Finally unit-2 & 3 & Kotehswar(THDC)-Koteshwar(Pooling) ckt 2 tripped. As per PMU data, no fault was observed. However, dip in frequency was observed indicating generation loss. Preliminary Report from Koteshwar(THDC) and Details from Koteshwar-Pool(PG) have been received while Detailed report along with DRs/EL from THDC is still awaited.

THDC may elaborate the incident and submit the analysis report to NRLDC/NRPC and may also apprise the members about the corrective actions already taken/being taken (with time line) to avoid such incidents in future.

x. Multiple element tripping at 400kV Dulhasti HEP(NHPC) on 16th July 2014 at 11:22hrs

Event category: GD-1 Generation loss: 260MW (NHPC may confirm) Loss of load: Nil

As reported at 11:22hrs of 16th July 2014, 400kV Kishenpur(PG)-Dulasti line tripped from Dulhasti end on account of DT(direct trip) received from Kishenpur(PG) end. As the line was the only evacuating line of the Hydro station, the running units #1 & #2 also tripped. No fault was reported from Dulhasti end. As per SCADA data SoE, 400kV Kishenpur-Dulhasti CB opened at Dulhasti end at 11:22:22.765hrs followed by tripping of Unit #1 & #2 in ~0.6 sec from tripping of line. Points require more clarity in understanding the tripping (As per NRLDC)-

1. Reason for DT command sent from Kishenpur(PG) end to be reviewed. Preliminary Report & EL from NHPC has been received whereas detailed report and DR/EL from POWERGRID yet to be received. POWERGRID/NHPC may elaborate the incident and submit the analysis report to NRLDC/NRPC and may also apprise the members about the corrective actions already taken/being taken (with time line) to avoid such incidents in future.

y. Multiple element tripping at 400kV Auraiya GPS(NTPC) on 25th July 2014 at

11:53hrs

Event category: GD-1 Generation loss: 100MW (NTPC may confirm) Loss of load: 350MW (As per SCADA data, UP may confirm) It was informed by UPPTCL site, that at 400kV S/S Auraiya, Y-phase C.T. of Kanpur ckt-1 bursted. At the same time 400kV Kanpur-Auraiya ckt-2, Kanpur-Agra(PG) D/C, 400/220kV ICT-1&2, 220kV Auraiya-Mehagaon & 220kV Auraiya-Malanpur ckt tripped. One ST (Steam Turbine) also tripped at the same time.


1. Two incidents of fault. Max dip in both the case is in Y-phase. First time fault duration was ~120ms & Second time fault duration was ~640ms

2. At 11:53:23.461hrs 400kV Auraiya-Kanpur ckt-1 tripped. 3. At 11:53:25.540hrs 400kV Agra(PG)-Auraiya D/C , Auraiya-Kanpur ckt-2 tripped.

Preliminary Report from NTPC and DR/EL from POWERGRID have been received. Detailed report from NTPC/POWERGRID yet to be received.

NTPC/POWERGRID may elaborate the incident and submit the analysis report to NRLDC/NRPC and may also apprise the members about corrective actions already taken/being taken (within time line) to avoid such events.

z. Multiple element tripping at 400kV Bassi(PG) on 27th July 2014 at 18:35hrs

Event category: GD-1 Generation loss: 400MW (Rajasthan may confirm) Loss of load: Nil (Rajasthan may confirm)

As reported 400kV Bassi-Kalisindh tripped on R-phase to earth fault along with Unit#1 of 400kV Kalisindh subsequently 400kV Agra-Bassi ckt-1 also tripped on over voltage protection operation.

It was reported by POWERGRID that 400kV Bassi-Kalisindh R-phase trip, line auto reclose from Bassi end but after 4second of auto reclosing DT received at Bassi end from remote end. It may be possible that line could not auto reclosed from Kalisindh end resulted into over voltage at Kalisindh end. 400kV Agra-Bassi ckt tripped on over voltage protection operation.


1. Fault clearing time~80ms 2. Fault occurred at 18:36:07.280hrs and Maximum dip in Y-phase voltage. 3. Bus voltage at 400kV Agra and Bassi was ~419.7kV & 427kV respectively

High voltage setting at Agra, Bassi & Kalisindh end needs to be reviewed.

DR/EL & Detailed Report has been received from POWERGRID but still awaited from Rajasthan.

POWERGRID/Rajasthan may elaborate the incident and submit the analysis report to NRLDC/NRPC and may also apprise the members about corrective actions already taken/being taken (within time line) to avoid such events.

nrldc agenda for 27th psc - · pdf fileat parichha tps, distance protection relay of 220 kv...

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