Minutes of

76th PCC Meeting

Date: 13.03.2019 Eastern Regional Power Committee

14, Golf Club Road, Tollygunge Kolkata: 700 033

EASTERN REGIONAL POWER COMMITTEE

MINUTES OF 76TH PROTECTION SUB-COMMITTEE MEETING HELD AT ERPC, KOLKATA ON 14.02.2019 (THURSDAY) AT 11:00 HOURS

List of participants is attached in Annexure-A. ERLDC presented the status of reports uploaded in the PDMS on-line reporting system and informed that few constituents were not uploading the reports in PDMS. ERLDC added that they are uploading their reports and PMU plots in PDMS and requested all the constituents to go through the reports and submit their observations in PDMS. PCC advised all the constituents to upload the reports in PDMS. ERLDC further explained that interlinking of DRs at the dashboard and detailed report may be implemented. PRDC agreed to refer the issue to their development team.

PART – A

ITEM NO. A.1: Confirmation of minutes of 75th Protection sub-Committee Meeting held on 22nd January, 2019 at ERPC, Kolkata.

The minutes of 75th Protection Sub-Committee meeting held on 22.01.19 circulated vide letter dated 06.02.19. Members may confirm the minutes of 75th PCC meeting. Deliberation in the meeting Members confirmed the minutes of 75th PCC meeting.

PART – B

ANALYSIS & DISCUSSION ON GRID INCIDENCES OCCURRED IN January, 2019 ITEM NO. B.1: Disturbance at 220kV New Bargarh S/S on 05-01-19 at 10:51 hrs. 220 kV New Bolangir - Bolangir (PG) was under shutdown. 220 kV New Bolangir - New Bargarh S/C was the only source to New Bolangir S/S. At 10:52 hrs, 160 MVA 220/132 kV ATR - I tripped on REF, differential protection at New Bargarh S/S. Simultaneously B/B protection operated at New Bargarh S/S which led the tripping of 220 kV New Bargarh - New Bolangir S/C, 220 kV New Bargarh - Katapalli S/C and 220/132 kV 160 MVA ATR - II followed by station black out of 220 kV New Bargarh and New Bolangir S/S. As per ERLDC SOE data, 400/220 kV ICT I & II tripped at Bolangir (PG) S/S (ICT II from both sides, ICT I from 220 kV side). Load loss 100 MW Fault was cleared within 100 ms as per the PMU data.

OPTCL and Powergrid may explain. Deliberation in the meeting OPTCL explained the disturbance with detailed presentation. The presentation is enclosed at Annexure-B1. OPTCL explained that REF protection of the 160MVA 220/132 kV ATR - I was initiated due to sensing of mismatch current from the NCT secondary and issued a trip command. At the same time, the LBB (96) relay of 160MVA 220/132 kV ATR - I was also initiated due to incorrect configuration. OPTCL added that 200 ms delay was also not incorporated in the LBB protection. As a result LBB protection had operated and tripped all the connected elements of 220KV Bus-1. OPTCL informed that the following corrective actions had been taken after the disturbance:

• The issue of CT mismatch from NCT secondary has been resolved • Settings and Logic of LBB had been revised • REF and LBB protections had been tested and found in order

ERLDC informed that analog channels and LBB related channels were not configured in the DR and advised OPTCL to configure the DR for better analysis of the disturbance. ITEM NO. B.2: Disturbance at 220 kV Katapalli S/s on 07.01.2019 at 15:40 hrs. 220 kV Katapalli - Bolangir S/C along with 220 kV Katapalli - Hindalco D/C, 132 kV Katapalli - Burla D/C and 132 kV Katapalli Chiplima D/C tripped due to snapping of R phase jumper of 220 kV Katapalli - Bolangir S/C. OPTCL may explain. Deliberation in the meeting OPTCL explained the disturbance with detailed presentation. The presentation is enclosed at Annexure-B2. OPTCL informed that Bolangir(PG) was the only source available at the time of disturbance. OPTCL explained that at 15:40 hrs, R-ph jumper of 220 kV Katapalli - Bolangir S/C line had fallen on Y-ph as a result the line got tripped from both the ends on zone 1. After tripping of the line, Hindalco line tripped on overload and Hindalco units got islanded but failed to sustain. OPTCL added that jumper tension points would be strengthen with twin jumpers to avoid such failures. PCC advised OPTCL to send the details of Hindalco islanding scheme to analyze the reasons behind failure of the islanding scheme during this disturbance. ITEM NO. B.3: Disturbance at 400kV Gaya(PG), 220kV Gaya and Bodhgaya on 05-01-19 at

11:20 hrs. 220 kV Gaya - Bodhgaya D/C and 220 kV Gaya Khijasarai D/C tripped on Y-B fault on both sides. At the same time, 220 kV Bodhgaya- Khijasarai D/C tripped from Khijasarai end. Relay indications are as follows:

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In PMU data, fault was cleared after 350 ms. Load loss 150 MW BSPTCL and Powergrid may explain. Deliberation in the meeting After deliberation, it was concluded that there was a Y-B fault in 220kV Gaya(PG)-Bodhgaya Line-I close to Gaya (PG) and the fault got cleared from Gaya(PG) end on zone 1 and Bodhgaya end on zone 2. At the same time, Gaya(PG) end of 220kV Gaya(PG)-Bodhgaya Line-II has seen the fault in zone 2 and tripped the line. 220kV Bodhgaya-Khijasarai line-I & II and 220kV Gaya(PG)-Khijasarai line I & II were also tripped from Khijasarai end. PCC observed that Gaya(PG) end of 220kV Gaya(PG)-Bodhgaya Line-II should see the fault in zone 3 in this case instead of zone 2. ERLDC informed that as per the DR, power swing was also detected by the relay but the relay had issued the trip command. PCC advised Powergrid to review the distance relay reach and power swing blocking settings of Gaya(PG) end of 220kV Gaya(PG)-Bodhgaya Line-II. PCC advised BSPTCL to review the Khijasarai end relay settings to avoid unwanted tripping at Khijasarai end and submit the relay settings to ERPC for inclusion in PDMS. ITEM NO. B.4: Disturbance at 400kV Gaya(PG), 220kV Gaya and Bodhgaya on 09-01-19 at

12:44 hrs. 220 KV Main Bus II at Gaya tripped at 12:44 Hrs along with '400/220 KV 315 MVA ICT II at Gaya, 220 KV Gaya-Khijasarai II, 220 KV Gaya-Sonenagar II, 220 KV Gaya-Dehri I, 220 KV Gaya-Bodhgaya I & 220 KV Bus Coupler at Gaya BSPTCL and Powergrid may explain. Deliberation in the meeting Powergrid informed that during GIS bay testing of 400/220kV ICT-III, the busbar protection got operated on SF6 lockout trip and issued trip command to all the elements connected to Bus II. PCC advised Powergrid to take care in future to avoid such unwanted trippings.

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ITEM NO. B.5: Disturbance at 220kV Hazipur on 23-01-19 at 12:33 hrs. All lines emanating from Hazipur tripped due to fire hazard in 220 kV GIS bay of Amnour at Hazipur due to SF6 gas leakage. BSPTCL may explain. Deliberation in the meeting BSPTCL informed that 220kV Hazipur-Fatua line-I GIS bay disc got damaged when operating signal given to Bus isolator from Sipara end during remote operation testing from BGCL. The line protection failed to trip the line and busbar protection had operated and tripped all the connected elements of 220kV Hazipur S/s. BSPTCL explained that Bus I & II of GIS were directly connected with existing AIS Bus I & II respectively and there is common busbar protection which is initiating the tripping for both buses of GIS and AIS. PCC advised BSPTCL to address the issue of disc damage of GIS bay with the concerned OEM and also advised to implement the bus sectionalizer to avoid complete blackout of the substation. ITEM NO. B.6: Disturbance at 400 kV Muzaffarpur S/s on 05.01.2019 at 06:56 hrs. 400 kV Muzaffarpur - Gorakhpur D/C & 400 kV Bus II at Muzaffarpur tripped. Powergrid may explain. Deliberation in the meeting Powergrid informed that, there was a Y-N fault in 400 kV Muzaffarpur - Gorakhpur line II. The relay issued trip command to respective CBs on unsuccessful A/R attempt. At the same time, 400 kV Muzaffarpur - Gorakhpur line - I tripped due to B-N fault followed by unsuccessful A/R attempt. But Y-ph pole at Muzaffarpur end was failed to open due to CB lockout. As a result LBB protection operated and tripped all the elements connected to Bus II. ERLDC explained that SOTF and distance zone was picked up due to B-N fault in line 1 should have been detected as evolving fault and the line should have tripped immediately. But line 1 tripped after 225 ms from A/R instant. PCC advised Powergrid to verify and submit the details to ERPC and ERLDC. ITEM NO. B.7: Disturbance at 400kV Bakreswar S/s on 21.01.2019 at 02:29 hrs. 220 kV bus II along with 400/220 kV ICT II at Bakreswar, 220 kV Bakreswar - Bidhannagar - II, 220 kV Barkreswar - Sadai - II, 220 kV Bakreswar - Bidhannagar - II tripped due to CT burst of 220 kV Bakreswar - Bidhannagar - II at Bakreswar end. WBPDCL and WBSETCL may explain. Deliberation in the meeting WBPDCL explained that all the elements connected to 220kV Bus II got tripped on busbar protection due to CT burst of 220 kV Bakreswar - Bidhannagar - II at Bakreswar end. WBPDCL added that the busbar protection is static relay, they are planning to replace with numerical relay by Mar 2020.

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On request, other constituents shared their experience on maintenance activities such as Oil DGA and condition monitoring of spares to minimize the CT Burst. ITEM NO. B.8: Disturbance at 220kV New Jalpaiguri S/s on 06.01.2019 at 20:34 hrs. 220KV NJP-TLDP IV-II, 220KV BINAGURI-NJP-I & 220 kV Bus I at NJP tripped. WBSETCL, Powergrid and TLDP may explain. Deliberation in the meeting WBSETCL explained that R-N fault was appeared at 220kV TLDP IV S/s due to failure of R-ph CT of 220kV TLDP III-TLDP IV line. TLDP III end cleared the fault in zone 2 and TLDP IV end cleared the fault in Zone 1. WBSETCL added that busbar protection of Main Bus I at 220kV NJP S/s was maloperated for the external fault in 220kV TLDP IV S/s and all the elements connected to 220kV Bus I got tripped. WBSETCL informed they had verified the busbar protection RADSA relay at NJP and no spillage current was observed at steady state. PCC advised to test the busbar protection during shutdown and also to verify for proper earthing of the substation. ITEM NO. B.9: Islanding of CESC on 19.01.19 at 1845 Hrs: ERLDC At 18:52 hrs. BBGS Unit-3 tripped due to Condenser Vacuum Low resulting in load shed through Unit Lock Out (ULO) scheme. At the same time all three 132 kV CESC Circuits tripped from WBSETCL Howrah Substation through operation of Back Up Overcurrent Relays causing islanding of CESC System from the Grid. Frequency in the islanded CESC system fell sharply causing Under-frequency relays to operate entailing load shed at different Frequency levels. Ultimately islanded Frequency rose and Restoration of Supply commenced from 18:55 Hrs. and all supply was restored at 19:10 hrs. CESC system was synchronized with grid at Kasba point of supply at 18:58 hrs. Synchronizing point of CESC system shifted from Kasba to Howrah point of supply at 20:43 hrs and BBGS Unit-3 again Synchronized at 20:57 hrs. Points of concern:

1. Setting of over current protection of tie lines needs to be done considering impedance of the tie line and their thermal capacity together.

2. Possibility of load shedding scheme design considering Tie line loading need to be explored.

3. DR time synchronization is extremely important for this tie line. Also installation of PMU for better performance monitoring may be thought of.

CESC may explain. Deliberation in the meeting CESC explained the disturbance with detailed presentation. The presentation is enclosed at Annexure-B9. CESC explained that BBGS Unit 3 tripped through Turbine trip relay operation (86T) due to “Condenser vacuum fall trip stage 2”. The generation of unit 3 was 240 MW. Load shedding scheme was initiated and it could shed 90 MW instead of 220 MW. As a result, the power flow increased in the tie lines 132kV Howrah(WBSETCL)-SRS S/C line and 132kV Howrah(WBSETCL)-BGSS D/C line. First, 132kV Howrah(WBSETCL)-BGSS line II tripped from Howrah(WBSETCL) end on backup 76th PCC Minutes

overcurrent protection as the current flowing through the line was 637 A and the backup O/C setting at Howrah(WBSETCL) was 600 A, 0.15 sec. Thereafter, 132kV Howrah(WBSETCL)-BGSS line I and 132kV Howrah(WBSETCL)-SRS S/C line tripped on backup O/C protection at Howrah(WBSETCL) end due to overload. After tripping of 132kV tie lines, CESC system got islanded and frequency started falling as connected load was 781 MW w.r.t Generation 491 MW. Different load rejection schemes were operated and rest of the CESC system was survived. After that CESC system was synchronised with GRID at EMSS point at 18:58 hrs. PCC observed that after tripping of BBGS Unit 3, the power flow in the tie lines 132kV Howrah(WBSETCL)-SRS S/C line and 132kV Howrah(WBSETCL)-BGSS D/C line was 278 A, 470 A and 637 A respectively. However, the backup overcurrent settings at Howrah(WBSETCL) end was 600 A, 0.15 sec for all the three lines. PCC advised CESC to explore the possibilities to minimise the uneven loading of the tie-lines. PCC also advised CESC to review the backup overcurrent settings at Howrah(WBSETCL) in consultation with WBSETCL. ITEM NO. B.10: Tripping of STATCOM at Rourkela on 06.01.19 at 20:06 hrs: ERLDC MSR 1 was brought into service due to system requirement by the Controller at 20:06:32 hrs on 06/01/19. 3X171 MVA coupling transformer tripped due to actuation of NGT ground over-current protection at 20:06:47 Hrs, which tripped both the main (41052) CB and tie (41152) CB, there by isolating the fault. Fault comes under the SVC bus bar zone. For fault in this zone is seen by the following protection

a. SVC Bus bar protection. 1. BB differential protection 2. Overcurrent protection 3. Ground fault overcurrent protection

b. Earthing transformer Protection 1. Displacement overvoltage protection 2. Earthing transformer overcurrent protection 3. Earthing transformer ground fault overcurrent protection

Now in this case as per report submitted by the utility “Earthing transformer ground fault overcurrent protection” operated. This protection has two stages:

1. Stage 1 is 150 % of Maximum continuous current of Earthing resistor with 2 sec delay 2. Stage 2 120 % of Maximum continuous earth current of SVC PLUS system with 0.05 sec

delay

So it is seen that stage 2 operated in this case. Fault was extremely high resistive in nature and took 2 sec to clear. In this context utility may explain the following:

1. Is this type of fault will only be cleared by Earthing transformer protection? Is SVC Bus bar protection not covering such fault as from TFR it is clear that SVC Bus Bar protection not triggered? If yes then is there any scope of setting modification to make it responsive to such fault?

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2. What is the performance of the voltage displacement based back up protection is not

clear from the data submitted. Utility may review the same and share their experience to the system operator for larger benefit of the system.

To review and find any scope of improvement of the protection performance existing activated protection function and their setting may be submitted to ERPC/ERLDC. Powergrid may explain. Deliberation in the meeting ERLDC informed that for single phase to earth fault in the bus bar zone “Earthing transformer ground fault over current “ operation was found to be as per the design however for any current between stage 1 and stage 2 setting of the above protection time delay is fixed to stage 1 delay. PCC advised POWERGRID to check possibility of using IDMT characteristics in coordination with all other protection to reduce the operation time. It was also observed that backup protection of the “Earthing transformer ground fault over current “ did not operate which is “voltage displacement” protection. PCC advised POWERGRID to investigate the reason and take necessary action. ITEM NO. B.11: Mutual effect 400kV Andal-Jamshedpur-II on 400 kV Adhunik-

Jamshedpur D/C: ERLDC During analysis of the tripping of 400kV Andal-Jamshedpur-II on 10.01.19 at 16:47 hrs it is found that whenever the above circuit is in service due to mutual effect the flow of the 400 kV Adhunik-Jamshedpur D/C is becoming different. Then on further analysis it is found that when the 400kV Andal-Jamshedpur-II is in service then Y phase current of the 400 kV Adhunik-Jamshedpur 1 & 2 becoming different and the difference is to the tune of 50 to 60 Amps. This may affect distance protection and in some other operational configuration this might create a problem for other protections also On verbal communication with the site it is found that while entering the Jamshedpur station 400 kV Andal-Jamshedpur-I and II are on single circuit horizontal tower and Andal-Jamshedpur-II crossed both the circuit of 400 kV Adhunik-Jamshedpur. Being a small line 400 kV Adhunik-Jamshedpur D/C (300 meter) is having differential protection. Still it needs to be investigated and what precautions need to be taken may be discussed by the members. Also it is found that due to only a 400kV Andal-Jamshedpur-II line switching there is poorly damped oscillation in the 400kV Adhunik-Jamshedpur D/C, which shows there is a requirement of retuning of PSS Adhunik units. Members may discuss. Deliberation in the meeting PCC advised Adhunik and POWERGRID to analyze the event in detail to find the root cause in consultation with the ERPC and ERLDC. PCC also advised Adhunik to submit the details of PSS tuning to ERLDC/ERPC. ITEM NO. B.12: Tripping Incidences in the month of January, 2019. Other tripping incidences occurred in the month of January 2019 which needs explanation from

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constituents of either of the end is given in Annexure-B12. In 36th TCC, all the constituents were advised to use the PDMS on-line portal for uploading the single line tripping details along with DR (comtrade files), EL and other relevant files for all trippings of August 2017 onwards. Otherwise, it will be considered as violation of compliance of clause 5.2(r) & 5.9 of IEGC. In 74th PCC, all the constituents were requested to submit the disturbance report along with DR through the new version of on-line portal which was implemented from 01st Jan. 2019. Members may discuss. Deliberation in the meeting Members explained the tripping incidences. Updated status is enclosed at Annexure-B12.

1. 400 kV Barh-Patna-I on 27/01/19 at 06:47 Hrs

It is observedfrom Barh end DR that during the Y phase to earth fault,high neutral displacement took place and healthy B phase voltage has become more than 351 kV, which is more than stage 2 overvoltage setting. From the DR submitted by Barh, only “Any trip” is there and 3 phase tripping command has been issued. However, which protection has operated from Barh end is not clear during for this event. It is suspected that tripping command may have been issued by over voltage stage 2 trip. It is important to mention here that similar incident took place on 19/12/18 on the same circuit. Further, similar instances of such events has been observed in the recent past in ER system which has been brought to the notice of PCC forum where neutral displacement during fault has led to overvoltage stage 2 tripping of 400 kV lines. It may kindly be noted that as per CEA (Technical Standards for Connectivity to the Grid) Regulations, 2007- PART II 1.3 “earth fault factor of Generating station must be less than 1.4 , but as we found in this case earth fault factor is coming as more than 1.5 (350 kV/231 kV)”. In the above tripping of the line, this clause is not complied in view of which there is a need to form a joint expert committee for root cause analysis and suggesting corrective action.

2. 74th PCC Single line tripping of 400 KV Bihar sharif-Sasaram-1 on On 17/11/18 at 6:10 Hrs:

“On 17/11/18 at 6:10 Hrs 400 KV Sasaram-Bihar sharif-1 circuit tripped at Biharsharif end due to TEED protection operation as DC card failed. As the tripping command is issued to both Tie and main CB, the R,Y and B phase tripped however B phase Pole of Main CB closed again due to leakage in its pneumatic operating mechanism and went into lock out. However, as the pressure build up again in CB with time it again tripped in Pole discrepancy (which is persisting from the time of close). This pattern of opening and closing of B phase repeated for 30minutes, which can be observed from the line current of this circuit measured from the PMU at Bihar Sharif end. After this, the line was manually tripped from Sasaramend and faulty CB is isolated by operation of Isolator at Biharsharif at6:48 hrs.

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In view of the above issue, POWERGRID has been advised to submit a detail report and remedial measure taken to ensure such event does not take place in future.

PART- C:: OTHER ITEMS ITEM NO. C.1: Protection Audit and checking of relay settings in transmission

system/distribution system within States. CERC vide its order dated 26th March, 2018 in petition no. 09/SM/2015 directed RPCs to take up the issue of protection audit and relay settings in transmission system/distribution system within states. In 75th PCC, all the states were advised to submit the present practice which is being followed to carry out protection audit and checking of relay settings in transmission system/distribution system within the states. Members may update. Deliberation in the meeting PCC advised all the states to submit the present practice which is being followed to carry out protection audit and checking of relay settings in transmission system/distribution system within the states. ITEM NO. C.2: Total Power Failure at 220/132 kV Sonenagar(BSPTCL) S/s on 24.12.2018 at

23:28 Hrs. 220 kV Gaya Sonenagar D/C tripped on R-N fault leading to a load loss at Sonenagar and its nearby area. Load Loss: 115 MW

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In 75th PCC, BSPTCL informed that there was a transient R-N fault in 220 kV Sonenagar-Gaya-II circuit. Sonenagar end cleared the fault in zone-I protection but the autorecloser was not successful whereas autorecloser was successful at 220 kV Gaya end. BSPTCL informed that at the same time 220 kV Sonenagar-Gaya-I circuit also tripped only from Sonenagar end. During analysis of the disturbance, it was noticed that before opening of all the breakers of 220 kV Sonenagar-Gaya-I at Sonenagar end, the R-pole has been opened. The opening of R pole breaker could not be explained. PCC advised BSPTCL to submit the PSL logic to ERPC. Regarding tripping of 220 kV Sonenagar-Gaya-I, the relay settings were verified using PDMS and found that O/C highset setting was enabled for the circuit which caused tripping of the feeder instantaneously. PCC advised BSPTCL to disable the highset settings immediately and also advised to disable the highset protection in all the transmission lines of BSPTCL system. Thereafter, BSPTCL had submitted the PSL logic to ERPC. ERPC in consultation with PRDC had submitted the following comments to BSPTCL:

1. Zone1 fault was directly assigned to master trip due to this master trip will be operated for zone 1 fault and also auto reclose will get blocked.

2. Any trip-R, Any trip-Y & Any trip-B was assigned to Trip circuits R, Y & B respectively.

BSPTCL may update. Deliberation in the meeting BSPTCL agreed to modify the PSL logic. ITEM NO. C.3: Disturbance at 400/220 kV Alipurduar (Powergrid) S/s on 05.12.18 at 10:29

hrs. 400 kV Alipurduar-Bongaigaon D/C and 220 kV Alipurduar-Salakati D/C tripped along with pole-III of HVDC Alipurduar during a disturbance occurred in 400 kV Bongaigaon S/s. HVDC Alipurduar pole IV was under shutdown. Generation/Load Loss: Nil In 75th PCC, It was informed that there was a fault in 400 kV Bongaigaon S/s which was not cleared from the local end. 400 kV Alipurduar-Bongaigaon D/C tripped from Alipurduar end in zone-II of distance protection clearing the fault successfully from Alipurduar end. Powergrid informed that 220 kV Alipurduar-Salakati D/C did not trip during the incident and remain in charged condition. ERLDC had placed a report along with their observations which is enclosed at Annexure-C3. Regarding tripping of pole-III of HVDC Alipurduar, Powergrid informed that as the BNC-Alipurduar-Agra is multilink HVDC, BNC and Alipurduar stations are interlinked with each other. The tripping of all the poles at BNC station due to complete blackout at 400 kV Bongaigaon s/s, subsequently caused the tripping of pole-III in Alipurduar HVDC link.

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Powergrid informed that they have referred the issue to OEM i.e. M/s ABB for change of scheme in multilink operation so that incase of complete blackout in BNC or in Alipurduar, the other station will remain functional. Powergrid may update. Deliberation in the meeting PCC advised Powergrid submit the latest status to ERPC and ERLDC. ITEM NO. C.4: Installation of back-up distance relay in 220KV Bus-sectionaliser at

Binaguri SS--Powergrid 400/220KV Binaguri (New-Siliguri ) substation having extended 220KV Bus to 220KV WBSETCL (NJP) substation and both buses are isolated by 220KV bus-sectionaliser breaker. Separate bus-bar protections are installed at both end i.e. POWERGRID & WBSETCL to trip the sectionaliser CB in case of bus fault only. There is no directional relay installed in either end to isolate the faulty section in case of through fault occurred at remote station. Therefore if any of the protection fails to operate in downstream may cause 220KV Bus dead at POWERGRID end. Therefore, Powergrid is planning to install Distance protection relay as a back-up protection in 220KV Sectionaliser bay to take care remote end fault if primary protection fails to clear. In 75th PCC, WBSETCL was advised to send their comments to Powergrid on implementation of distance protection at 220kV Bus sectionaliser as a back-up protection. WBSETCL may update. Deliberation in the meeting WBSETCL agreed implement the same. ITEM NO. C.5: FOLLOW-UP OF DECISIONS OF THE PREVIOUS PROTECTION SUB-

COMMITTEE MEETING(S)

The decisions of previous PCC Meetings are given at Annexure-C5. In 73rd PCC, it was observed that latest status on the implementation of the previous PCC recommendations were not updated by the constituents regularly. All the constituents were advised to update the latest status of the recommendations as per the list given in Annexure. Members may update the latest status. Deliberation in the meeting Updated status is enclosed at Annexure-C5. ITEM NO. C.6: Schedule of training program to be conducted by PRDC PRDC, as per the AMC, is going to conduct 2nd training programme on PDMS and PSCT in state utility premises of Eastern Region. The tentative schedule is given below: Sl no. State Location Date Training

1. West Bengal NJP 04.02.2019-05.02.2019 on PDMS Durgapur 07.02.2019-08.02.2019

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2. Bihar North Bihar 08.04.2019-09.04.2019

South Bihar 11.04.2019-12.04.2019 3. Sikkim - 03.06.2019-04.06.2019 4. Odisha - 08.07.2019-09.07.2019 5. Jharkhand - 05.08.2019-06.08.2019 6. For All States ERPC 02.09.2019-06.09.2019 on PSCT

Members may update. Deliberation in the meeting Members noted. ITEM NO. C.7: Zone 3 settings of ISTS lines Based on the data available in PDMS, the zone 3 settings of all ISTS lines in Eastern Region were verified and compared with the corresponding resistive reach of the line thermal loading. Zone 3 settings were also checked with the agreed protection philosophy of ER. The discrepancies observed in the settings will be presented in the meeting. In 67th PCC, PRDC presented the list of ISTS lines where they observed the discrepancy in zone-3 setting. In 73rd PCC, It was informed that Powergrid ER-I had verified the settings. Powergrid ER-II and Powergrid odisha will verify the settings at the earliest. In 74th PCC, Powergrid & DVC informed that they will submit the details at the earliest. DVC has submitted the zone settings data vide mail dated 16.01.19. Members may update. Deliberation in the meeting PCC advised all the other transmission utilities to submit the details at the earliest. ITEM NO. C.8: Status of Third Party Protection Audit The compliance status of 1st Third Party Protection Audit observations is as follows:

Name of Constituents Total Observations Complied % of

Compliance Powergrid 54 46 85.19 NTPC 16 14 87.50 NHPC 1 1 100.00 DVC 40 26 65.00 WB 68 49 72.06 Odisha 59 42 71.19 JUSNL 34 25 73.53 BSPTCL 16 5 31.25 IPP (GMR, Sterlite and MPL) 5 5 100.00

* Pending observations of Powergrid are related to PLCC problems at other end.

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The substation wise status of compliance are available at ERPC website (Observations include PLCC rectification/activation which needs a comprehensive plan). Members may note. Deliberation in the meeting Members noted. ITEM NO. C.9: Non-commissioning of PLCC / OPGW and non-implementation of carrier

aided tripping in 220kV and above lines. According to CEA technical standard for construction of electric plants and electric lines -Clause 43(4) (c), transmission line of 220 KV and above should have single-phase auto-reclosing facility for improving the availability of the lines. However, from the tripping details attached June-August, 2016 it is evident that the some of 220kV above Inter & Intra-Regional lines do not having auto-reclose facility either at one end or at both ends. Out of these for some of the lines even PLCC/OPGW is not yet installed and carrier aided protection including Autorecloser facility is not yet implemented. Based on the trippings of June- August, 2016 and PMU analysis a list of such lines has been prepared and as given below:

List of line where auto reclose facility is not available(Information based on PMU data analysis)

S. No

Transmission Lines name

Date of Tripping

Reason of Tripping

Owner Detail Present Status

End-1 End-2 OPGW/PLCC Link available

AR facility functional

13 220KV BUDIPADAR-KORBA-II

23.06.16 Y-N FAULT OPTCL CSEB PLCC

available

will be activated in consultation with Korba

17 220 KV TSTPP-RENGALI

17.07.16

EARTH FAULT NTPC OPTCL

by March 2018

18 220KV BUDIPADAR-RAIGARH

21.07.16

EARTH FAULT OPTCL PGCIL PLCC

defective

20 220 KV FARAKKA-LALMATIA

03.08.16 B-N FAULT . NTPC JUNSL

Yes Old Relay and not functional. 7-8 months required for auto re-close relay procurement.

23 220 KV MUZAFFARPUR - HAZIPUR - II

10.08.16 B-N FAULT PGCIL BSPTCL

Voice established. For carrier required shutdown

24 220 KV ROURKELA - TARKERA-II

11.08.16 B-N FAULT PGCIL OPTCL OPGW

available

Expected to install protection coupler by Jan 17

76th PCC Minutes

27 220 KV BIHARSARIF-TENUGHAT

07.09.16 B-N FAULT BSPTC

L TVNL

33 220KV Jamshedpur-Jindal-SC

34th TCC advised all the respective members to update the above list along with the last tripping status in next PCC meeting. TCC further advised all the constituents to give the latest status of PLCC of other 220kV and above lines under respective control area. OPTCL:

1. 220kV Rengali(PG)-Rengali S/Y (Proposal for Commn. in OPGW is pending): PSDF appraisal committee accepted the proposal

2. 220kV Indravati(PG)-Indravati(PH) (Proposal for Commn. in OPGW pending): PSDF appraisal committee accepted the proposal

3. 132kV Baripada(PG)-Baripada ( Tendering in Progress for OPGW): Contract awarded 4. 132kV Baripada(PG)-Rairangpur (Tendering in Progress for OPGW): Contract awarded

BSPTCL:

Sl No. Lines Status 1 220 kV Purnea(PG)-Madhepura Protection through PLCC is working properly 2 220 kV Biharsharif-BTPS new Commissioning of PLCC is under progress. 3 220 kV BTPS new- Begusarai Commissioning of PLCC is under progress. 4 220 kV Biharshariff-Bodhgaya line LILO

at Khizersarai OPGW is present. Protection is done through DPC.

5 220kV MTPS-Motiari line OPGW is installed. 6 220KV Madhepura-New Purnea D/C Protection through PLCC is working properly 7 220KV Muzaffarpur-Hajipur D/C line Protection through PLCC is working properly 8 220KV Patna-Khagaul-SC PLCC Panel working properly.

Members may update. Deliberation in the meeting Members noted. ITEM NO. C.10: Disturbance monitoring equipment(DME) standardization The power system is routinely subjected to faults or disturbances which can range from transient faults on transmission lines to system-wide disturbances involving multiple control areas, states and even countries. Investigation of each incident is critical in optimizing the performance of protection systems with the goal of preventing future incidents from becoming wide-area disturbances. The tools required to perform post-incident analyses include DME which can capture pre-event, event, and post-event conditions with a high degree of accuracy. Recorders can be classified into two categories: • FR (Fault Recorder) • Sequence of events Recorder (SER) For FR (Fault Recorder) following points may be standardized:

a. Deployment b. Record Length c. Triggers

76th PCC Minutes

d. Sampling Rates

For Sequence of events Recorder following points may be standardized:

a. SER Capability b. Point Assignments c. Use of RTUs for SER

Common issues:

a. Data format b. Power Supply c. Monitoring

Reference documents for this:

1. NERC Standard PRC-002-2 Disturbance Monitoring and Reporting Requirements 2. NPCC Regional Reliability Reference Directory # 11 Disturbance Monitoring Equipment

Criteria In 74th PCC, all the constituents were advised to submit their comments/observations relating to the draft standard. PCC also decided similar kind of standard would be prepared for Transformer Protection and Busbar Protection. In 75th PCC, PRDC presented the draft standard for Transformer Protection and Busbar Protection. Draft standard is enclosed at Annexure-C10. Members may update.

Deliberation in the meeting PCC advised all the members to submit their comments to ERLDC and ERPC at the earliest. ITEM NO. C.11: Additional Agenda 1. Third Party Protection Audit in Sikkim

Sikkim informed that there are 20 nos. substations (132 / 66 kV and 66 /11 kV) of ENPD, Govt. of Sikkim requiring 3rd Party Protection Audit by ERPC team to be carried out for the purpose of PSDF funding. Deliberation in the meeting PCC decided to conduct the Protection Audit for 08 nos. substations located in west & south Sikkim during 12/03/2019 to 16/03/2019. PCC advised Powergrid, ERLDC and West Bengal to nominate a protection engineer for the audit. PCC decided that the remaining substations in Sikkim would be completed during March / April, 2019.

***************

3/11/2019

1

Tripping of 220KV system at New Bargarh Grid S/s on 05.01.2019.

Date 05.01.2019 ,Time- 10:52 Hrs. Station : New Bargarh 220/132/33kV GSS Weather : Sunny. 220KV Bus coupler and Transfer Bus coupler breaker were in OFF

condition. 220KV Bolangir(New)-Bolangir(PG) line was under shutdown for

maintenance work and New Bargarh Sub-station was availingpower supply from Katapali Grid Sub-station.

PRE-FAULT CONDITION

LOAD FLOW DETAILS AT 10.00HRS220KV BUS-1

220KV BUS-2

220KV TRANSFER

BUS

KATAPALI 160MVAAUT0-1

BOLANGIR(NEW)160MVAAUT0-2

TBCB/C

89A

89B

89C

89T 89T 89T 89T 89T

89C 89C 89C

89B 89B 89B 89B

89A 89A89A 89A 89A

89B52 52

5252 52 52

119MW 10MW8MW 101MW

Annexure-B1

3/11/2019

2

DURING FAULT CONDITIONBUS-1 (KATAPALI, AUTO-1,AUTO-2 & BOLANGIR(NEW)

220KV BUS-1

220KV BUS-2

220KV TRANSFER

BUS

KATAPALI 160MVAAUT0-1

BOLANGIR(NEW)160MVAAUT0-2

TBCB/C

89A

89B

89C

89T 89T 89T 89T 89T

89C 89C 89C

89B 89B 89B 89B

89A 89A89A 89A 89A

89B52 52

5252 52 52

Sl.No. Name of feeder Relay IndicationNew Bargarh end Remote end

1 220 kV Katapali Bus bar Relay (Make-GE,Type-B90), LBB Optd.

No Trip

2 220 kV Bolangir(new) Bus bar Relay (Make-GE,Type-B90), LBB Optd.

No Trip

3 100MVA Auto-2 Bus bar Relay (Make-GE,Type-B90), LBB Optd.

NA

4 160MVA Auto-1 REF relay optd.(GE-T60 Relay)96-LBB optd.

NA

Date & Time of Occurrence:05.01.2019, 10.52 Hrs

3/11/2019

3

Analysis:-On dtd. 05.01.19 at 10.52Hrs., the 160MVA Auto

Transformer-1 tripped on REF protection due to sensing ofmismatch current from the NCT secondary. At the sameinstance the LBB (96) relay of Auto-1 was also initiated andissue an external LBB command to Bus-bar relay resultingtripping of all the feeder & Auto TFR connected to 220KVBus-1.

REMEDIAL MEASURES:

1. The NCT ckt. Checked in the REF relay incorporatedin T60 relay.

2. LBB logic and setting of relays have been reviewed.3. The relays and CT ckts. have been checked & tested.

3/13/2019

1

System disturbance occurred at 220/132/33 KV KatapaliGSS on 07.01.2019.

• Date 07.01.2019 ,Time- 15.40 Hrs.• Station : Katapali 220/132/33kV GSS• 220 KV PGCIL feeder tripped from this end on Z1 operation at 15.40 Hrs .• 220 KV New Bargarh feeder was on H/T at 15.10 Hrs as per the instruction

of SLDC.• 220KV Lapanga-2 feeder was on TBC.• 220 KV Hindalco feeder tripped at their End.

Load flow at 15.00 Hrs at Katapali Gss.

Name of the feeder Load in MW Load Flow

220 KV Lapanga 1 +5.2 Out

220 KV Lapanga 2 +5.2 Out

220 KV Hindalco 1 +9.0 Out220 KV Hindalco 2 +9.0 Out

220 KV PGCIL -78.9 In

220 KV New Bargarh -70.4 In

Auto TRF-1 +34.8 Out

Auto Trf-2 +34.8 OutAuto TRF-3 +54.0 Out

PGCIL Line was the only source to Katapali and Lapanga Grid during fault occurrence.

Annexure-B2

3/13/2019

2

PRE-FAULT CONDITIONLOAD FLOW DETAILS AT 15.00HRS

220KV BUS-2

220KV TRANSFER

BUS

PGCIL 100MVAAUT0-1

TBC

89A

89C

89T 89T

89A

89B

89C 89C

89B 89B 89B

89A 89A 89A 89A

89B

52 52 52 52

89B

NEWBARGARH

52

89T

52

100MVAAUT0-2

89T

89C

89T

89A

52

89B

89C

89T89T89T89T

89C89C89C

52 52

HINDALCO-2 HINDALCO-1LAPANGA-2

LAPANGA

89A

89C

52

89A89A89A

89B89B89B

160MVAAUT0-3

52

BC

89T

89B

220KV BUS-1

POST-FAULT CONDITIONALL FEEDERS & AUTO TFR’S ARE IN BUS-2

220KV BUS-2

220KV TRANSFER

BUS

PGCIL 100MVAAUT0-1

TBC

89A

89C

89T 89T

89A

89B

89C 89C

89B 89B 89B

89A 89A 89A 89A

89B

52 52 52 52

89B

NEWBARGARH

52

89T

52

100MVAAUT0-2

89T

89C

89T

89A

52

89B

89C

89T89T89T89T

89C89C89C

52 52

HINDALCO-2 HINDALCO-1LAPANGA-2

LAPANGA

89A

89C

52

89A89A89A

89B89B89B

160MVAAUT0-3

52

BC

89T

89B

220KV BUS-1

FAULT DUE TO SNAPPING OF R-

JUMPER

3/13/2019

3

Time Name of feeder Relay IndicationKatapali End Remote end

15.40 hrs 220 kV PGCIL Main- 1(Micom P444)Z1, FD=746.5 mtrFault Current:Ia =2.6 KAIb= 3.09 KAIc= 438.5 Amp

Main- 1Z1, FD=87.7KmFault Current:Ia =1.57 KAIb= 1.56KA

Main 2 (ABB- REL 670)Z1 , FD=0.3 %Fault Current :Ia =2.56 KAIb= 3.03 KAIc-=439 Amp

Main 2 Z1 ,Z2 optd.Fault Current :Ia =1.79 KAIb= 1.79 KA

Date & Time of Occurrence: 07.01.2019 15.40 Hrs,

Analysis:-

1. At 15.40 Hrs. 220 KV PGCIL feeder tripped with Z1 fault.2. After Physical verification, it was found that R-ph jumper

snapped at Loc-04 of PGCIL Line and fallen on Y-Ph.3. Both the DP relays of Main-1 & Main-2 at Katapali End

Showing same Z1 fault.

3/13/2019

4

Remedial Measures

** The jumper at tension point of lines are to be made twin jumper at selected points.

3/13/2019

1

System Disturbance on 19.01.2019 in CESC System

Date: 14.02.2019

Network Prior to System Disturbance

Annexure-B9

3/13/2019

2

Prior to event relevant System data:

GENERATION

BBGS U1 220 MWBBGS U2 215 MWBBGS U3 240 MWSGS U1 56 MWTOTAL 731 MW

IMPORT FROM SYNC. POINT 140 MW

IMPORT FROM OTHER. POINTS

LILUAH 40 MWTRS 20 MW

RISHRA 87 MWSGSS 185 MWTOTAL 332 MW

HEL GENERATION 540 MW

TOTAL SYSTEM MET 1203 MW (731+140+332)

• CESC was synchronised at Howrah Point.

• Import from WBSETCL Howrah through circuit 1 was 109A, circuit 2 was 272A and through circuit 3 was 363A.

• Overall schedule export was 219 MW from SGSS.

• ULO for BBGS Unit 3 Load shedding scheme for 91 MW was in service

Sequence of Events

Sequence of Events /Analysis:

• BBGS Unit 3 tripped through Turbine trip relay operation (86T) due to “Condenser vacuum fall trip stage 2”. So GT 3 tripped at 18:52:16.701 hrs. as per SCADA log.

• Unit Lock-out tripping of 91 MW occurred at various stations as per ULO trip selection scheme.

• After tripping of BBGS Unit 3, current of W1 at SRS, W2 & W3 at BGSS were around 278 A, 470 A and 637 A respectively . As B/U Over Current setting of W1, W2 and W3 are 600 A, 0.15 at WBSETCL Howrah end, W3 tripped at 18:52:37.130 hrs. as per SCADA log from WBSETCL end ( Bot. end SCADA stamping :- 18:52:51:908 hrs.). Thus, W3 tripping occurred 18.429 seconds after the tripping of GT 3 at BBGS.

• After tripping of W3, current of W2 was 997 A and W2 tripped at 18:52:39.236 hrs. Thus, W2 tripping occurred 2.133 seconds after the tripping of W3 through B/U O/C relay operation at WBSETCL end.

• Subsequent to W2 tripping, entire 290 MW (Import: 140 + BBGS U3 GEN.:240 – ULO trip: 91) was thrown on W1 circuit. So approx. 1364 A was flowing from WBSETCL Howrah to SRS via W1 circuit. Thereby causing the tripping of W1 circuit at 18:52:40.479 hrs. (1.243 seconds after the tripping of W2) through B/U O/C relay operation at WBSETCL end.

• After tripping of W1, CESC system was islanded and frequency started falling as connected load was 781 MW (Sys. Met: 1203 – Radial import: 332 – ULO SHED: 90) and Gen. was 491 MW (U1:220 + U2:215 + SGS:56).

• As frequency fell below the set limit, load rejection of 183 MW occurred between 49.2 to 48.6 Hz.

3/13/2019

3

• At 47.8 Hz, SRS W2 (BGSS-2) and W3 (BGSS-3) tripped through U/F protection operation of split relay. (LED 7 of Spilt relay came which is for Under / Over Frequency. Split relay operated at U/F setting of is 47.8 Hz, 0.5 seconds).

• At SRS, BGSS-2 (was on M1 Bus) tripped at 18:52:42.119 hrs. However, BGSS-3 was on Transfer Bus and Bus Coupler tripped at 18:52:42.145 hrs. Simultaneously around 54 MW at Bot. SS was thrown from the system due to tripping of BGSS 2 and 3 circuit from SRS.

• Finally at 47.7 Hz, 60 MW from East Cal. SS was thrown due to operation of U/F relay.

• Thereafter frequency started improving and system was stable.

• After that CESC system was synchronised with GRID at EMSS point at 18:58 hrs.

Sequence of Events

Sequence of Events in tabular form:

BBGS GT3 WBSEB-BGSS CKT 3/3A WBSEB-BGSS CKT 2 WBSEB-SRS CKT 1 At SRS BGSS2 CKT. At SRS BGSS3 CKT.

Setting 1.8MW, 2SEC 600A,0.15 600A,0.15 600A,0.15 U/F 47.8 Hz, 0.5 Sec U/F 47.8 Hz, 0.5 Sec

Tripping SCADA time stamp

18.52.16.701 18:52:37:130 18:52:39:236 18:52:49:479 18:52:42:119 18:52:42:145

Tripped through LOW FORWARD POWER

51ABC 51ABC 51ABC U/F U/F

Current before U#3 tripping

363A 272A 109A NA NA

Current after U#3 tripping

637A 470A 278A NA NACurrent after tripping of W3

NIL 997A 353A NA NACurrent after tripping of W2

NIL NIL 1364A NA NACurrent before tripping of BGSS 2 &3

132A 106A

3/13/2019

4

Record: At WBSETCL HOW CKT CESC-III

18:52:37.130 hrs

Record: At WBSETCL HOW CKT CESC-II

18:52:39.236 hrs

3/13/2019

5

18:52:49:479 hrs

Record: At WBSETCL HOW CKT CESC-I

LINE NAME TRIP DATETRIP TIME

RESTORATION DATE

RESTORATION TIME

Relay Indication LOCAL END

Relay Indication REMOTE END Reason Fault Clearance time in msec

Remarks PCC remarks

220KV BEGUSARAI-NEW PURNEA-II 03-01-2019 22:39 04-01-2019 0:20 DID NOT TRIP DT RECEIVED AT PURNEA END DT RECEIVED AT PURNEA END -- Mal operation of PLCC as reported by BSPTCL220KV BEGUSARAI-NEW PURNEA-II 04-01-2019 17:27 04-01-2019 17:51 DID NOT TRIP DT RECEIVED AT PURNEA END. DT RECEIVED AT PURNEA END. No Fault observed in PMU Mal operation of PLCC as reported by BSPTCL220KV BEGUSARAI-NEW PURNEA-II 04-01-2019 22:51 04-01-2019 23:32 DT RECEIVED AT PURNEA END. DT RECEIVED AT PURNEA END. Mal operation of PLCC as reported by BSPTCL

220KV BEGUSARAI-NEW PURNEA-II 05-01-2019 8:07 05-01-2019 18:32 Z-1 ,56.60 KM Y-N 2.66 KA 130 KM ,F.C 1.41 KA Y-N A/R SUCCESSFUL Y-N Fault < 100 ms No Auto RecloseA/R function at Begusarai end need to be ensured

by BSPTCL

220KV BEGUSARAI-NEW PURNEA-I 08-01-2019 12:02 29-01-2019 15:36 B-N .79 KA,66.6 KM B-N Fault No Auto RecloseA/R function at Begusarai end need to beensured

by BSPTCL220KV BEGUSARAI-NEW PURNEA-II 08-01-2019 14:44 08-01-2019 15:11 DT RECEIVED AT PURNEA END. DT RECEIVED AT PURNEA END. -- No Fault observed in PMU Mal operation of PLCC as reported by BSPTCL220KV BEGUSARAI-NEW PURNEA-II 08-01-2019 15:26 DT RECEIVED AT PURNEA END. DT RECEIVED AT PURNEA END. -- Mal operation of PLCC as reported by BSPTCL

220KV BEGUSARAI-NEW PURNEA-II 20-01-2019 5:55 20-01-2019 6:51 RN, Z1, 1.81 KA,102.4 KM R-N Fault < 100 ms No Auto RecloseA/R function at Begusarai end need to be ensured

by BSPTCL400KV FSTPP-BAHARAMPUR-II 09-01-2019 11:04 09-01-2019 11:21 No indication DT received DT received at Baharampur -- No Fault observed in PMU PLCC problem

400KV FSTPP-KhSTPP-III 12-01-2019 11:00 12-01-2019 11:22 DT RECEIVED AT FSTPP DT RECEIVED AT FSTPP -- No Fault observed in PMU PLCC problem, informed to PG, PG will check400KV LAPANGA-STERLITE-II 16-01-2019 20:00 18-01-2019 16:48 DT RECEIVED AT STERLITE DT RECEIVED AT STERLITE PLCC problem

400KV MERAMUNDALI-LAPANGA-II 17-01-2019 12:40 17-01-2019 20:10 PLCC PROBLEM PLCC PROBLEM AT MEERAMUNDALI PLCC problem220KV DALKHOLA (WB)-DALKHOLA (PG)-II 23-01-2019 14:21 23-01-2019 15:58 Tripped form Dalkola(PG) end only Tripped form Dalkola(PG) end only -- No Fault observed in PMU Contact issue, Solved

400KV LAPANGA-STERLITE-II 28-01-2019 2:56 28-01-2019 10:52 DT RECEIVED AT LAPANGA END DT RECEIVED AT LAPANGA END B-N fault observed in PMU PLCC problem

220KV STPS(WBSEB)-CHANDIL-SC 01-01-2019 2:52 01-01-2019 3:15R-PH Z1 3.172 KA 41.61 KM,

A/R successfulR-PH ,Z1,62.98 KM,2.293 KA R-N Fault < 100 ms No Auto Reclose A/R at Chandil to be ensured by JUSNL

220KV CHANDIL-STPS(WBSEB)-I 03-01-2019 3:59 03-01-2019 4:35 Y-N, F/C=1.9KA,Z-1 A/R successful Y-N Fault No Auto Reclose A/R at Chandil to be ensured by JUSNL400KV MUZAFFARPUR-GORAKHPUR-II 05-01-2019 4:40 05-01-2019 5:45 BN, 194.7 KM, 2.994 KA B-N Fault < 100 ms No Auto Reclose Carrier received at Muzaffarpur

220KV DEHRI-GAYA-I 06-01-2019 11:51 06-01-2019 12:23 Z-1, 1.72 KA 55.97 KM A/R SUCCESSFUL B-N,36.45 Km,3.95 KA R-N Fault < 100 ms No Auto Reclose

Both Y & B pole breaker opened at Gaya end during A/R operation. Same incident repeated on 21st and 22nd January also. PGCIL ER-I to check

and reply

400KV KHARAGPUR-CHAIBASA-II 07-01-2019 14:19 07-01-2019 14:43 Successful A/R B-N, 159.5KM, 2.82KA B-N Fault < 100 ms No Auto ReclosePGCIL ER-I to share the reason for A/R lockout at

Chaibasa end

400KV INDRAVATI(PG)-INDRAVATI(GR)-SC 08-01-2019 9:24 08-01-2019 12:49 B-N Fault B-N Fault 300 msec No Auto RecloseOpening of B pole tie breaker at Indravati (PG) end is not captured in DR; PGCIL to check and

reply220KV PANDIABILI-SAMANGARA-I 23-01-2019 3:11 23-01-2019 3:56 b-n , f/c-7.5ka , f/d-15km B-N Fault < 100 ms No Auto Reclose PLCC problem

765KV FATEHPUR-PUSAULI-I 25-01-2019 8:35 25-01-2019 10:09 Z1, RN, 186.89 KM, 1.66 KA R-N Fault < 100 ms No Auto RecloseA/R started at PG; But three phase tie breakers tripped at Sasaram end without any initiation

delay.

Autoreclose related issues

Miscellaneous: High Fault clearing time, Tripping on DT, No Fault observed in PMU

List of Intra Regional line tripping in the month of January 2019 where violation of protection standard has been observed

Annexure-B12

Queries on NER Disturbance on 05/12/18 At 10:19:05:945 hrs R-phase isolator of Bus reactor at Bongaigaon opened due to DC supply extension. This resulted in a fault near to the Bongaigaon 400kV Bus which is cleared by tripping of all lines either in zone-2 from remote end or in zone-4 from Bongaigaon end. By 10:19:06:470 hrs AC system fault got cleared. NER remain connected to ER by 220 kV Alipurduar-Salakati D/C.

Following this tripping HVDC BNC-AGRA pole 1 and 2 and APD-AGRA pole 3 tripped. Few issues observed in this HVDC tripping are pointed below:

Queries:

1. In TFR captured from MC2 of APD, every 4th analog signal up to 52th signal is missing. Inaddition to this 72,84,88,99 and 100thanalog signals also missing. In digital channel 4,34 to 36, 47to 48, 53 and 104thsignal are missing. Reason for the missing signals in the comtrade file mayplease be explained by PGCIL. It may kindly be noted that as per IEEE Comtrade Standard (IEEEC37.111-2013), the no of analog and digital channel recorded is mentioned in the 2ndline of theconfiguration file (.cfg) and these are also available in the comtrade data file. And in this case, itis showing 100 analog and 104 digital channels recorded but many are missing in between in thedata file. Please find the snapshot from the configuration file.

AC system fault clearance

HVDC restart and blocking of pole 1 &

3and

Annexure-C3

2. This event was an AC system fault however it was found that the two HVDC poles have tripped on DC line protection. The reason for the operation of DC line protection on AC fault may please be explained by PGCIL.

3. It is well known that low AC voltage can lead to pick up of DC line protection but there is some interlock to avoid wrong operation of DC line protection. It may kindly be intimated that was there any scope of avoiding DC protection operation by tuning interlock setting?

4. In DC line protection, derivative and level parts are present. Are these two parts are kept in AND logic or OR logic?What is the setting of derivative and level part of DC line protection? This will help in understanding the logic for DC line protection.

5. It is desired that the setting of low AC voltage blocking used to block DC protection during AC system disturbance mayalso be submitted. This will help in understanding the tripping of HVDC at ERLDC for any future event.

6. Alipurduar end AC system become healthy as soon as the fault is cleared, but as the DC line is common that’s why due to persisting low voltage at BNC, APD could not bring the DC voltage to normal. So that APD-AGRA section could have been saved.The relevant plots are given below for Alipurdwar end, BNC end and PMU plot of NER nodes. In such scenario,whether protective de-paralleling of only BNC converters was possible to safe guard healthy part of the network. PGCIL may study the possibility with OEM and intimate the ERLDC/ERPC on the finding.

As seen from both PMU plot and DR plots that even after the fault clearing NER system continue to have oscillatory low voltage whereas AlipurduarAC system voltage recovered following fault clearing. DR plots are as below: At APD end: pole 3:

At BNC end: pole 1:

AC voltage become Normal after fault clearing

AC voltage could not revive

DC voltage

DC Power

DC Current

DC voltage

DC Power

DC Current

7. Also from DR of APD it is seen that approximately 1 sec 800 ms after the blocking of HVDC pole at Alipurduar again around 480 kV Dc voltage is appearing is the line. This may be explained by PGCIL in order to understand the complete event and its progress.

AC voltage also become zero and after 1.8 sec it again appears

Sl No.

Name of the incidence PCC Recommendation Latest status

74th PCC Meeting

1. Multiple tripping incident at Darbhanga at 13:33 hrs on 06-11-18 and at 15:23 hrs on 06-11-18

PCC suggested to keep the highset setting more than 7 and advised DMTCL to review the settings.

2. Tripping of 400 kV KTPP-Kharagpur-2 & 400 KTPP-New Chanditala S/C at 12:21 hrs on 23.11.18

PCC advised WBPDCL to submit a report explaining the following points.

• Reason for tripping of Y & B phase breaker in 400 KTPP-New Chanditala S/C line and subsequently non-operation of pole discrepancy relay at KTPP end.

• Reason for sending carrier signal from KTPP end to New Chanditala end.

• Reason for delayed opening of R-phase breaker(manually) of 400 KTPP-New Chanditala S/C line at KTPP end.

PCC also advised WBSETCL and WBPDCL to verify the DEF status for 400 KTPP-New Chanditala S/C line at respective end.

WBPDCL informed that the pole discrepancy relay was found healthy. The reason for operation of PD relay on that day could not be found out.

3. Total power failure at 220kV Hatia (JUSNL) S/s on 20.07.18 at 09:10 hrs.

PCC also advised JUSNL to test the healthiness of the relays at 220kV Patratu and 220/132kV Hatia S/s on urgent basis.

JUSNL informed that testing for healthiness of relays will be done by third party vendor. The work has already been awarded to the vendor and it will be completed by February’ 19.

73rd PCC Meeting

4. Total Power failure at 220 kV Hatia (JUSNL) substation on 03.10.18 at 17:23 hrs and on 04.10.18 at 00:26 hrs

PCC advised JUSNL to test the Bus bar and LBB protection, PLCC and configuration of DT signal in the relay at Hatia end.

JUSNL informed that the testing of PLCC and Protection system will be completed by

ANNEXURE-C5

February’ 19. 5. Total Power failure at TLDP-III

S/s on 27.10.18 at 10:24 hrs.

PCC advised WBSETCL and NHPC to review the DEF settings for proper protection coordination between the transmission lines and generating station.

PCC advised PRDC to coordinate the settings with reference to GT of TLDP side.

6. Disturbance at Purnea From DR it was observed that DEF protection of 220 kV Purnea(PG)-Purnea line at PG end did not reset even after Neutral current reduced to negligible value.

72nd PCC Meeting

7. HVDC TFR triggering standardization and reporting requirements.

PCC advised POWERGRID to submit TFR triggering criteria and TFR signal list for all HVDC station of Eastern region to ERLDC

71st PCC Meeting

8. Disturbance at 220/132 kV Motipur(BSPTCL) S/s on 15.08.18 at 13:00 hrs.

PCC advised BSPTCL to check the disturbance recorders of all the lines in 220 kV Motipur S/s and communicate the findings to ERPC/ERLDC at the earliest.

BSPTCL informed that DR of 15.08.18 is not available in the relay. They added that OEM will visit the station for reconfiguration of relay.

9. Disturbance at 400 kV Farakka S/s on 19.08.18 at 15:26 hrs.

PCC advised NTPC to replace/divert Micom P437 relay to avoid unwanted tripping of such important transmission line. PCC also advised to check the reason for not sending carrier from Farakka to Kahalgaon and non-operation of Autorecloser.

NTPC informed that the relay has been

replaced. They added that the carrier

healthiness will be checked at next

available shutdown.

68th PCC Meeting

10. Issues related with Generation Backing down during Talcher-Kolar SPS operation on 16th May 2018.

PCC advised Powergrid to explore for inclusion of pole block with ground return mode signal in the SPS logic. PCC advised NTPC also to explore for inclusion of pole block with ground return mode signal in the SPS logic.

Powergrid informed that the issue was referred to OEM but OEM was not responding.

PCC advised Powergrid to coordinate with Kolar end as the same issue has already been resolved at their end.

11. Issue of Protection Coordination Observed during Blackout of Tala on 23rd May 2018.

PCC advised Bhutan representatives to submit a detailed report on the above disturbance to ERPC and ERLDC at the earliest.

ERPC Proposed Guide Lines

Triggering criteria for DR : Any Start

Internal protection trip signals, external trigger input, analog triggering (any phase current exceeding 1.5 pu of CT secondary current or any phase voltage below 0.8pu, neutral/residual overcurrent greater than 0.25pu of CT secondary current).

DR time window : minimum 3 seconds. minimum 2 seconds.Pre-fault time window (S): 0.5 -Post fault time window (S): 2.5 0.3Minimum sampling frequency: 1000 Hz 64 Samples Per CycleAnalog signals as per priorityA. Mandatory signals:

1. Three phase voltage 1. Three phase-to-neutral voltages2. Neutral voltage 2. Three phase currents and neutral currents.3. Three phase current 3. Neutral Currents4. Neutral current 4. Frequency

B. Optional signals:1. Mutual current 1. Polarizing currents and voltages, if used.2. Check Sync 2. Real and reactive power

3. Open Delta

The Minimum parameters to be monitored in the Fault record shall be specified by therespective RPC.

Digital signals as per priorityA. Mandatory signals:

1. Any Start2. Any trip3. Z1, Z2, Z3, Z4 pick up4. Over current and Earth fault pick up5. Over voltage stage I & II pick up6. DT send & reverse7. Carrier send & Receive8. Main three phase CB open signal9. Tie three phase CB open signal (where applicable)10. Power Swing11. SOTF/TOR12. LBB13. A/R L/O14. Main-1/2 operated15. Bus Bar trip16. VT failure17. Distance Forward & Reverse18. T1, T2, T3, T419. Broken conductor20. 86A & 86B21. A/R 1P In Prog22. A/R Fail23. STUB/TEED (where applicable)

B. Optional signals:1. Any External input2. Any Binary Input

Annexure-C10

ERPC Proposed Guide Lines

Triggering criteria for DR : Any Start

Internal protection trip signals, external trigger input, analog triggering (any phase current exceeding 1.5 pu of CT secondary current or any phase voltage below 0.8pu, neutral/residual overcurrent greater than 0.25pu of CT secondary current).

DR time window : minimum 3 seconds. minimum 2 seconds.Pre-fault time window (S): 0.5 -Post fault time window (S): 2.5 0.3Minimum sampling frequency: 3200Hz 64 Samples Per CycleAnalog signals as per priorityA. Mandatory signals:

1. Three Phase Currents & Neutral Currents of HV2. Three Phase Currents & Neutral Currents of LV3. Three Phase Currents & Neutral Currents of MV4. I Ref HV5. I Ref LV6. I Ref MV7. Voltages8. Frequency9. Differential Currents10. Restraining Currents11. Low Impedence REF-DIFF - of all windings12. Low Impedence REF-Restraining - of all windings

Digital signals as per priority1. Any Start2. Any trip3. Differential Trip3. REF Trip HV, MV & LV4. Over-current Trip5. Earth Fault Trip6. Over Flux7. Over Voltage8. Under Voltage9. 2nd Harmonic10. 5th Harmonic11. Frequency Protection12. External Trip Signals

ERPC Proposed Guide Lines

Triggering criteria for DR : Any Start

Internal protection trip signals, external trigger input, analog triggering (any phase current exceeding 1.5 pu of CT secondary current or any phase voltage below 0.8pu, neutral/residual overcurrent greater than 0.25pu of CT secondary current).

DR time window : minimum 3 seconds. minimum 2 seconds.Pre-fault time window (S): 0.5 -Post fault time window (S): 2.5 0.3Minimum sampling frequency: 3200Hz 64 Samples Per CycleAnalog signals as per priorityA. Mandatory signals: 1. 3Phase Diff Current

2. 3Phase Bias Current3. Neutral Differential Current4. Neutral Bias Current

B. Optional Signals: 1. Individual Feeder Currenrts if available2. Zone wise Differential and Bias Currents

Digital signals as per priority1. Any Start2. Any trip3. R-Phase Fault4. Y-Phase Fault5. B-Phase Fault6. Earth Fault7. Check Zone Operated8. Zone 1 BB Fault9. Zone 2 BB Fault10. Trip Bus bar Zone 1 11. Trip Bus bar Zone 212. Trip Breaker Failure Zone 113. Trip Breaker Failure Zone 214. Bus bar Differential Blocked