1. CONFIRMATION OF THE MINUTES OF THE 14 th PROTECTION SUB- COMMITTEE MEETING HELD ON 21 st March Grid Disturbances in the Southern Region

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2 SOUTHERN REGIONAL POWER COMMITTEE BANGALORE AGNEDA FOR THE 15 th MEETING OF PROTECTION SUB- OF SRPC TO BE HELD ON COMMITTEE 1. CONFIRMATION OF THE MINUTES OF THE 14 th PROTECTION SUB- COMMITTEE MEETING HELD ON 21 st March SYSTEM DISTURBANCES The System Disturbances / Occurrences in the Southern Region showing Details of Grid disturbances, Grid Incidences and the details of Talcher Kolar HVDC pole tripping Incidences are given in Annexure- I as given by SRLDC vide Lr. No SRLDC/SRC&S/Prot/2012 /4559 dt (Annexure II). 3. Grid Disturbances in the Southern Region 3.1 Grid Disturbance on 3 rd April 2012 (i) Time and date of event : 3 rd April 2012 at Hrs (ii) Location : North Karnataka (iii) Plant and/or Equipment directly involved : North coastal Karnataka and 400 kv Guttur SS, 400kV Kaiga SS, 400kV Narendra and Nagjheri, Kodasalli, Kadra, Kaiga, Narendra, Hubli, Bidnal, Guttur and Ambewadi S/S become dead. (iv) Description and cause of event At 11:01 Hrs, due to a suspected momentary DC grounding of the isolator NO/NC contact wires running from individual bay bus selection 1

3 isolator to 400kv bus bar protection relay panel, Bus bar protection relay operated at 400kV Guttur. (v) Antecedent conditions of load and generation, including frequency, voltage and the flows in the affected area at the time of tripping including Weather Condition prior to the event It is requested that the above data before by (KPTCL). may be submitted on or (vi) Demand / Generation interrupted Generation Loss MW and Load Loss 2000 MW (vii) Duration of Interruption, All Relevant system data including copies of records of all recording instruments including Disturbance Recorder, Event Logger, DAS (viii) Sequence of trippings with time. (ix) Details of Relay Flags (x) Remedial measures It is requested that the above data (item vii to x) may be submitted on or before by (KPTCL). 3.2 Grid Disturbance on 18 th April 2012 (i) Time and date of event : 18 th April 2012 at Hrs (ii) Location : Neyveli,Tamilnadu (iii) Plant and/or Equipment directly involved : Neyveli TPS KV Sub station 2

4 (iv) Description and cause of event At 09:23:39 Hrs, Due to internal fault in the B-phase SF6 CT of 400 KV Neyveli-TPS- Puducherry line, SF6 pressure has come down to zero and feeder got tripped. During the auto reclosing at 09:23:40 Hrs both the 400 KV buses got cleared on Bus bar protection. Neyveli TPS 2 Stage II Units 4, 5, 6 & 7 went on house load and 400 KV Neyveli TPS 2 buses (Double Main one Transfer Bus scheme) became dead. (v) Antecedent conditions of load and generation, including frequency, voltage and the flows in the affected area at the time of tripping including Weather Condition prior to the event It is requested that the above data may be submitted on or before by (NLC). (vi) Demand / Generation interrupted Generation Loss- 850 MW (vii) Duration of interruption, All Relevant system data including copies of records of all recording instruments including Disturbance Recorder, Event Logger, DAS (viii) Sequence of trippings with time. (ix) Details of Relay Flags (x) Remedial measures It is requested that the above data (item vii to x) may be submitted on or before by (NLC). 3

5 3.3 Grid Disturbance on 27 th April 2012 (i) Time and date of event : 27 th April 2012 at Hrs (ii) Location : Guttur, Karnataka (iii) Plant and/or Equipment directly involved : (iv) 400 KV Guttur Substation Description and cause of event A Bus fault occurred at 400kV Guttur SS due to flashover of B- phase Lightening Arrester of 400kV Guttur-Hiriyur-Line 2. Bus bar protection operated and all 400 KV feeders got tripped along with 400/220 KV ICTs. (v) Antecedent conditions of load and generation, including frequency, voltage and the flows in the affected area at the time of tripping including Weather Condition prior to the event It is requested that the above data may be submitted on or before by (KPTCL). (vi) Demand / Generation interrupted Generation Loss- 415 MW (vii) Duration of interruption, All Relevant system data including copies of records of all recording instruments including Disturbance Recorder, Event Logger, DAS (viii) Sequence of trippings with time. (ix) Details of Relay Flags (x) Remedial measures It is requested that the above data (item vii to x) may be submitted on or before by (KPTCL). 4

6 4. Grid Incidences in the Southern Region 4.1) Grid Incidence in VTS Generating station on (i) Time and date of event : 18 th May 2012 at Hrs (ii) Location : VTS Generating station (iii) Plant and/or Equipment directly involved : (iv) VTS Generating station Description and cause of event 220kV Bus-II at VTS Generating station got cleared due to Bus fault. The fault was created due to CT blast on 220kV VTS- Tadikonda-II feeder. Out of 6 units three units, Unit # 2, 3 & 6, got tripped (v) Antecedent conditions of load and generation, including frequency, voltage and the flows in the affected area at the time of tripping including Weather Condition prior to the event It is requested that the above data may be submitted on or before by (APTRANSCO). (vi) Demand / Generation interrupted Generation Loss- 600 MW. (vii) Duration of interruption, All Relevant system data including copies of records of all recording instruments including Disturbance Recorder, Event Logger, DAS (viii) Sequence of trippings with time. (ix) Details of Relay Flags (x) Remedial measures It is requested that the above data (item vii to x) may be submitted on or before by (APTRANSCO). 5

7 4.2) Talcher Kolar Pole Trippings S No Details of Event Date & Time Reason Kolar SPS Talcher SPS Remarks Talcher-Kolar Pole-1 tripped and Pole-2 came on Metallic Return mode. Power Flow came down from 2460MW to 387 MW. Frequency came down from Hz to 49.18Hz. Talcher-Kolar Pole- 1&2 tripped. Power Flow came down from 1970 MW to 0 MW. Frequency came down from Hz to 48.88Hz. Talcher-Kolar Pole-1 tripped and Pole-2 came on Ground Return mode. Power Flow came down from 1970MW to 147MW. Frequency came down from Hz to 49.16Hz. Talcher-Kolar Pole-2 tripped and Pole-1 came on Ground Return mode. Power Flow came down from 1970MW to 147MW. Frequency came down from Hz to 49.16Hz. Due to failure of 24 Volt DC power supply to pole control system due to short circuit in ATR OE4 card. Pole -1 & 2 tripped due to Commutation failure, which was happened due to R-phase CT blast of 220kV Somanahalli- HSR layout at Somanahalli end. 400/220kV Somanahalli ICT-1&2 Tripped on backup over current protection. Due to HVDC line fault at Location no 56, km from Talcher end. Due to HVDC line fault at Location no 57, km from Talcher end. Inter trip signal-1 generated SPS not operated Inter trip signal-1&2 generated Inter trip signal-1&2 generated Unit#5 and Unit#6 tripped Unit # 6 tripped and Generati on of Unit#4& 5 back down by 150 MW each. Unit # 6 tripped and Generati on of Unit#4& 5 back down by 150 MW each Unit # 6 tripped and Generati on of Unit#5 back down by 150 MW. The Grid Incidence was Discussed in the 14 the PCC Meeting. It is requested that the Details of Event Report as envisaged in the IEGC (c) for the above incidents may be sent latest by (SRTS II,PGCIL). 6

8 5. Minor Trippings The Minor tripping in the Southern Region are given in Annexure III as submitted by SRLDC vide Lr No SRLDC/SRC&S/Prot/2012 /4559 dt Requirement of SPS for 400 KV Nellore-Almatti DC line contingency: SRLDC Vide Lr No Lr No SRLDC/SRC&S/Prot/2012 /4559 dt (item No 5) proposed for a System Protection Scheme for 400 KV Nellore-Almatti DC Line contingency. With the commissioning of Simhapuri (300 MW) and Meenakshi (300 MW) 400 KV Nellore-Almatty DC line will get severely loaded. The strengthening of this corridor would be achieved with the Commissioning of the Nellore-Thiruvalam line which is expected by the year SRLDC is proposing an SPS to back down generation at Simhapuri & Meenakshi to alleviate the post contingency flows on N-1 condition of this line. Members may discuss. 7. SPS for 220kV Chittur- Tiruvalum and 220kV Sullurpet- Gummidipoondi lines: SRLDC Vide Lr No Lr No SRLDC/SRC&S/Prot/2012 /4559 dt (item No 15) proposed for a System Protection Scheme for 220kV Chittur-Tiruvalum and 220 KV Sullurpet-Gummidipoondi lines. Presently, 220 KV Chittur-Tiruvalum line O/C setting at Chittur end is 420 A (160 MW) and 220 KV Sullurpet-Gummidipoondi line O/C setting at Sullurpet end is 260 A (100 MW). The constraint is due to the loading 7

9 concern on the upstream lines. Considering this fact it is prudent to design an SPS to trip 220 KV Chittur- Tiruvalum and 220 KV Sullurpet- Gummidipoondi lines based on the loading of the critical upstream lines instead of over current protection and Line will be protected by distance protection. Members may discuss kv Hiriyur-Nelamangala D/C Contingency SPS Proposal for a SPS in 400 KV Hiriyur Nelamangala Line was discussed in the PCC and OCC meetings. In view of proposed commissioning of Bellary TPS Unit-II a SPS during tripping of one circuit of 400 kv Hiriyur-Nelamangala line when flow of each line was more than 560 MW was deliberated in the meetings. It was informed that 400kV Hiriyur-Nelamangala SPS was implemented partially (tripping of Jindal units were wired, BTPS final link for tripping yet to be extended). It was noted in the 72 nd meeting of OCC that the SPS scheme was under active implementation by KPTCL. It was informed that the remaining pending works would be completed in about one monts time. The status of the SPS may be intimated to the forum. 9. SPS at Hosur S/S The SPS at Hosur proposal was discussed in the PCC & OCC meetings. In the meetings PGCIL stressed for the immediate need for SPS at Hosur S/S till ICT-III gets commissioned. This was in order to avoid overloading of the surviving ICT in case of tripping of one ICT. After deliberations, Protection Committee had recommended that 8

10 TANTRANSCO to identify the loads which could be tripped in contingency to avoid overloading of ICT at Hosur. The scheme was discussed in the 19 th SRPC meeting held on 1 st June The Committee had approved the SPS for 400 kv Hosur ICT as proposed. It was also seen that the SPS scheme would be implemented without affecting the loads of Karnataka and Tamil Nadu. SRTS II,PGCIL vide Lr No SR II/O&M/ /F-42.0 dt informed that the controlled load shedding of 315 MVA ICTs at 400/220 KV Hosur S/s to mitigate the overloading of one ICT in case of tripping of other has been implemented w.e.f Status of provision of SPS Trip Signal 3 at Kolar The proposal for Generation of third protection signal from Kolar in view of higher power transfer (2000 to 2500 MW) was approved in 13 th SRPC meeting. In 14 th PCC meeting SRTSII, PGCIL informed that inter trip signal-3 would be ready by May The Extended mode of operation of Talcher-Kolar HVDC link would continue throughout the year as decided in SRPC meeting held on 1 st June The Trip Signal 3 to cover loss of 2500 MW is required to be in place at the earliest and it would also be ensured that the other 2 Trip signals are generated and acted upon. The status of provision of SPS trip signal 3 may be informed to the forum. 9

11 11. Modification of SPS Trip Signal at Kolar SRTS II, PGCIL vide dt informed that the modifications as suggested in the special meeting of PCC have been implemented on PGCIL also informed that the revised logics were uploaded in the PLC and tested locally and found to be working. The revised logic is enclosed as follows. Trip generation LOGIC Condition 1: ((500MW<Power loss :S1000MW) & Pole Block) OR (l400mw< Power flow :S1900MW) & Pole Block) OR (under one pole s/d (500MW<Power flow <1000MW)) other Pole Blocks= TRIP I Condition 2: (650MW<Power flow :S1150MW) & Line fault & Pole Block = TRIP I Condition 3: ((Power loss >1000MW) & Pole Block OR (Power flow >1900MW) & Pole Block) OR (under one pole s/d (Power flow> 1000MW)) other Pole Blocks = TRIP II Condition 4: (Power flow> 1150MW) & Line fault & Pole Block = TRIP II *Power loss = DC power at Kolar at (t-2sec) - DC power at Kolar at (t) where t is the time instant when Block signal is available. Power flow = DC power at Kolar at (t-2sec). 12. SPS for Kudankulam The following had been noted up to the 14 th PCC meeting It was informed that all the substation works has been completed and the substation was energized. PGCIL/SRTS II informed the forum that the SPS would be ready by April The PCC forum requested SRTS II / PGCIL to commission the SPS within the agreed date. The status of implementation of SPS may be informed to the forum. 10

12 13. SPS at Varahi The PCC forum envisaged a SPS at Varahi in the earlier PCC meetings. Approximately 1050 MW ( more than 450 MW at Varahi and 600 MW of UPCL) had to be evacuated through 220 kv Varahi Shimoga D/C line and 220 kv Kemar Shimoga S/C. It was informed that 220 kv Varahi Shimoga D/C line severely loaded with no N-1 reliability. Up to 14 th PCC the following pointes were minuted: The PCC forum proposed to have an SPS scheme at Varahi, which can trip the generation in the event of 220 kv Varahi Shimoga line outage. If any one of the three lines i.e. Varahi- Shimoga Line 1&2 and Kemar - Shimoga Line trips Varahi generation has to be brought to 100 MW (at present two units has to be tripped) to avoid over loading of other lines in the corridor. When the Fourth unit of Varahi comes into operation (i.e. all the four units are generating to its full capacity ) and if any one of the above stated three line trips, three units of Varahi should be tripped to maintain the generating capacity around 100 MW. KPCL to identify the tripping sequence of units considering supply to the auxiliaries are not affected by tripping of units. KPCL will be the implementing agency for the SPS scheme. The Scheme will be reviewed when Nandikur- Shantigrama 400 KV (Quad moose Conductor) line commissioned by KPTCL. KPTCL informed the forum that KPTCL part of works in the SPS were completed and they were waiting for KPCL clearance. The progress of work regarding provision of SPS may be intimated to the forum. 11

13 14. SPS for S1-S2 bid area: The PCC forum had suggested for an SPS to shed loads of 300 MW at Salem to limit post contingency stress in S1-S2 corridor whenever one of 400 KV Hosur-Salem and 400 KV Somanahalli-Salem line trips. Up to 14 th PCC the following the following were noted: The SPS proposal was discussed in various SRPC forum meetings and TANTRANSCO had agreed to implement the same. TANTRANSCO had identified the loads to be shed in the SPS scheme and also given a cost estimate of Rs. 25 lakhs to implement the scheme. Loads were identified by TANTRANSCO and the wiring and associated works will be taken up by them. The higher loading will be utilized to operate Kadamparai Power House in pump mode operation. SRLDC informed that the app cost of PLC and wiring would be around ` 50 lakhs apart from ` 25 lakhs for TANTRANSCO portion. The forum is on the opinion that the feeders should be tripped automatically and not through manual intervention. CE, TANTRANSCO informed that loads were identified and the SPS works will be started at the earliest. The issue was discussed in the 70 th- 72 nd OCC and the OCC forum also requested TANTRANSCO to implement the SPS at the earliest. The status of the SPS may be intimated to the forum. 15. SPS at Muddanur: The PCC forum proposed a SPS at Muddanur in the earlier PCC meetings. The Muddanur generation (about 800 MW) has to be evacuated through four 220 kv lines, 220 kv D/C Chinnakampally and 220 kv D/C Ananthapur and radial loadings of 200 kv Pulivendula (120 12

14 MW) and 220 kv Yerraguntla (80 MW). In case of tripping of one of the lines of 220 kv Chinnakampally other line get over loaded and may lead to cascade tripping. Up to 14 th PCC meeting the following points were minuted: The SPS scheme was proposed to back down generation in case of one or both 220 kv Muddanur-Chinnakampally lines trips. It was also informed that the SPS would be reviewed keeping in views of commissioning of Lines / Generating units at Rayal Seema. APTRANSCO informed the forum that by June 2012 the SPS would be operational. APTRANSCO also informed that unit No 5 was identified to back down the generation (as a part of SPS). The status of the SPS may be intimated to the forum. 16. SPS on 400 kv Vijayawada-Nellore line: The PCC forum proposed a SPS to back down generation at Vemagiri complex in case of tripping of one of the 400 kv Vijayawada- Nellore line when each line carrying 550 MW. The issue was discussed in various SRPC forum meetings and SRLDC had also provided additional study results. The PCC forum requested APTRANSCO in co-ordination with the IPPs / SRTS I (PGCIL) would implement the SPS within the agreed time. The issue was discussed in the 19th SRPC meeting held on 1st June After discussions, it had been decided that a Sub Group consisting of members from constituents would be formed to deliberate on the scheme and suggest any review, in the changed scenario. The deliberations of this Sub Group would be put up to Special TCC for consideration. 13

15 17. Operation of various SPS Scheme in the Southern Region Up to 14 th PCC the following were minuted: The PCC forum opined that the operation of Various SPS schemes in the Southern Region may be brought to the notice of the forum during the PCC meeting. The forum proposed that the operation, non operation and mal operation of the SPS schemes would be reported to the forum and discussed in the forth coming PCC meeting. The forum requested all the constituents to send the particulars of operation, non operation and mal operation of the SPS schemes to the SRPC Secretariat at the earliest. All the constituents are requested to send the particulars of operation, non operation and mal operation of SPS in the their system latest by through . In the sub group meeting of PCC held on 30 th April at Kaiga it was proposed to review the existing SPS at Nagjheri to take care of line loadings on Bidnal-Harthi and Hubli-Sirsi lines (action KPTCL).The copy of the meeting is enclosed as Annexure IV. 18. Uniformity in Protection Philosophy in SR (i) TANTANSCO vide Lr No CE/P&C/SE/D/EPC2/AEE3/f SRPC/Dt given the following agenda. 14

16 (ii) KSEB vide Lr No.CESO/EELD1/AE2GS/ PC/ dt nil sent the following agenda In the 12th meeting of the Special Protection committee, it was decided to adopt a zone II timing of 350 msec for having a uniform protection philosophy in the Southern region. Based on that, the Zone II timing for majority of 220kV feeders in our region have been changed to 350msec. But it was noticed that the setting of the feeders at Power grid end was non-uniform and because of this grading is not achieved. The current settings of the PGCIL feeders are listed below. Name of feeder end current Zone#2 setting at PGCIL kV PGCIL #1 at PothencodeS/s 450msec kV PGCIL #2 at PothencodeS/s 450msec 3. Edamon- Thirunelveli#1 at EdamonS/s 300msec 4. Edamon- Thirunelveli#2 at Edamon S/s 300msec 5. Kundara- Kayamkulam at Kayamkulam GIS S/s 500msec 6. Edappon- Kayamkulam at Kayamkulam GIS 500msec Members may discuss. 19. Provision of Single Phase Auto-Reclosing, Carrier Aided tripping and Bus Bar Protection Scheme on 220 KV and above lines in SR. In the earlier PCC meetings, it was agreed to have single phase auto- Reclosing scheme on all lines emanating from all major generating stations including nuclear stations and on all 220 kv and above rated lines. The PCC forum recommended that all the constituents to have carrier aided tripping for all the 220 KV and above rated lines. The forum also recommended that all the constituents to have an independent Bus Bar protection scheme to protect their transmission system elements. It was also decided to create a data base of lines provided with Single phase/three Phase Auto Reclosing facility, Lines provided with carrier aided 15

17 tripping and Sub stations provided with Bus bar Protection Scheme. All the constituents had been requested to submit the requested data for base creation Up to 14 th PCC meeting the following points were minuted: As on date the status of data submitted by the constituents is as follows. S.No Constituent 1 APTRANSCO Carrier Aided Tripping Status Data Submitted Single Phase Auto reclosing status Data Submitted Bus Bar Protection status Data * Submitted 2 KSEB Data Submitted Data submitted Data* Submitted 3 KPTCL Data Submitted Data submitted Data* Submitted 4 TANTRANSCO Data Submitted Data submitted Data* submitted 5 SRTS I,PGCIL Data Not submitted Data Not submitted Data Not* submitted 6 SRTS II,PGCIL Data Submitted Data submitted Data Submitted 6 NTPC Data Not ^ submitted Data Not ^ submitted Data Not * submitted 7 NLC Data Submitted Data Submitted Data Submitted 8 MAPS,NPCIL Data Not ^ submitted Data Not ^ submitted Data Not * submitted 9 KAIGA,NPCIL Data Not ^ submitted Data Not ^ submitted Data Not * submitted 10 Puducherry Data Submitted Data submitted Data submitted * Requested to send the updated List of Substations provided with Bus Bar Protection in as per the Annexure V. 16

18 ^ Requested to send the updated List of Lines provided with Carrier Aided Tripping /Single Phase Auto Reclosing scheme as per the Annexure VI. It is requested that all the constituents may send the updated status of implementation of provision of Carrier Aided Protection facility, Single Phase Auto reclose facility and provision of Bus Bar Protection facility in the 220 KV and above network in Electronic format latest by to the following IDs Agenda from SRTS II,PGCIL SRTS II,PGCIL vide E Mail sent the following Agenda i. Commissioning of carrier aided protection scheme for all 220 kv lines ii. Overloading of ICTs at Thirunelveli & Madurai- Requirement of SPS scheme: The Thirunelveli & Madurai ICTs are operating at near to full load and operating at overloads intermittently. The requirement of SPS may please be discussed in the meeting. iii. Submission of tripping reports to SRLDC/SRPC by all utilities. Members may discuss. 21. Islanding scheme for Jindal, BTPS. An islanding scheme covering Munirabad, Kustagi Sindhanur Loads and JSW Generators was proposed in the earlier PCC meetings. It was brought to notice of the forum that M/s. Jindal has an islanding scheme in operation where 1 x 100 MW and 1 x 133 MW units island with 180 MW load of its steel plant. As JSW has a load of 500 MW, M/s. Jindal was asked to explore possibility of a second island. M/s. 17

19 KPTCL / KPCL was also requested to formulate an island for BTPS with radial loads at Munirabad, Kustagi and Sindhanur. Up to 14 th PCC meeting the following points were minuted: It was informed that the 400 kv double circuit line between BTPS and Hiriyur and second unit of 500 MW at BTPS are expected to be commissioned in shortly. KPTCL submitted the Islanding scheme for management approval by keeping 1 unit of 300 MW at JSW. The following Loads were identified by KPTCL for the proposed islanding scheme. Kustagi :107 MW, Sindhanur:55 MW, Munirabad:49 MW,Alipur:80 MW,Total:291 MW. The status of provision of islanding scheme may be intimated to the forum. 22. Islanding Scheme for Kaiga The provision of Islanding scheme for Kaiga Generators was discussed in the earlier PCC meetings. Kaiga, NPCIL was requested to formulate the Kaiga islanding scheme with adjoining loads in consultation with SRLDC, KPTCL &PGCIL. Islanding scheme for Kaiga was discussed in detail in the 1 st meeting of monitoring committee held on and it was proposed to have two islands called Island12 and Island34. Details of scheme are attached as Annexure VII. The status of the formulation of Islanding Scheme may be intimated to the PCC forum. 18

20 23. Non Submission of complete tripping Report by the constituents. SRLDC vide Lr No SRLDC/SRC&S/Prot/2012 /4559 dt (item no 13) informed that though the constituents have started giving tripping reports for the trippings in their system most of the constituents are not submitting the DR/EL printouts. Members may discuss the issue. 24. Review of Installation of Frequency Trend Relays (df/dt) and revision of df/dt settings in SR The df/dt protection scheme is in operation in the Southern Regional grid with the following two settings. The details of the load relief obtained through this scheme is given in the table furnished below: Hz with rate of fall of 0.3Hz / sec. for alarm; & Hz with rate of fall of 0.3Hz / sec. instantaneous - for trip. df/dt Relays installed in Southern Region: S.NO Constituent System df/dt relay Setting Expected load relief (MW) 1 APTRANSCO 49.3 Hz, 0.3 Hz / Sec, 1767 Instantaneous 2 KPTCL -do- ( ) 3 TANTRANSCO -do KSEB -do- ( ) Total load relief in SR ( ) 19

21 The following had been noted up to the 14 th PCC meeting The PCC forum proposed a new df/dt settings for the SR system. Present df/dt Settings in SR: ALARM: Frequency <= 49.5 Hz and 0.3 Hz/sec fall of frequency (df/dt) Trip: Frequency <=49.3 Hz and 0.3 Hz/sec fall of frequency (df/dt) Then Load relief expected: 3530 MW in Peak condition 2909 MW in off Peak condition Proposed df/dt Settings in SR in addition to the existing setting: ALARM: Frequency <= 49.8 Hz and 0.2 Hz/sec fall of frequency (df/dt) Trip: Frequency <=49.5 Hz and 0.2 Hz/sec fall of frequency (df/dt) Then Load relief expected: 2000 MW in Peak condition. The settings would be reviewed when the system requires change in the revised settings. The issue was also discussed in the 70 th 72 nd OCC and the constituents were briefed about the revision in the df/dt settings. Progress of implementation of the scheme may be intimated to the forum. 25. The issue of sending completed Dynamic Study data In the 13 th PCC the forum decided to collect the Dynamic study data from the utilities to study the Southern Region system. The dynamic study format was circulated to the constituents to send the Generator, Excitation system, Governor, HVDC parameters.tneb, NLC, NTPC, Kayankulam and KSEB had submitted the filled format. 20

22 The forum opined that the dynamic study details of the IPPs also would be necessary to conduct the study on whole SR system. All the SLDCs were requested to direct the embedded IPPs connected at 220 KV and above voltage level to send the completed dynamic study format (Annexure VIII) to the SRPC, Secretariat. It is requested that the dynamic study data in the stipulated format may be sent to us latest by by to the following IDs NTPC (Ramagundam), KPCL, MAPS &KGS (NPCIL) were requested to send the dynamic study data (Annexure VIII) latest by Pilot PMU Project in the Southern Region. The pilot PMU project was approved in the 14 th SRPC meeting held at Kochi on 27 th August SRLDC proposed for 6 numbers of Phasor Measurement Units for the Southern Region at an estimated expenditure of Rs.4.0 Crores. The following had been noted up to the 14 th PCC meeting SRLDC informed the forum that SRLDC and KALKITECH had installed three Mini Pilot PMUs as a part of SRLDC WAMS Demo project. The mini Pilot PMUs were installed in 3 Locations (Hyderabad, Salem & Somanahally). The locations were selected based on locations where the power system and communication constraints persists. The mini Pilot PMUs were aimed to implement WAMs monitoring system and to understand communication and system architecture requirements. GM, SRLDC informed that 4 organizations had submitted their bids for installation of PMU and technical evaluation were going on. It was noted that the PMUs would be installed within 3 to 4 months time. The status of implementation of PMUs may be informed to the forum. 21

23 27. Expected UFRs load relief quantum: The Quantum of additional load relief to be provided by the constituents for the year as calculated by SRPC is given below. (Figures in MW) Constituents? AP KAR KER TN PUDU SR Stage Hz 25% Stage Hz 35% Stage - Hz 40% Total (implemented)? Additional Requirement? The constituents were requested to report the UFR trippings to SRPC at the earliest. The status of provision of designated relief may be intimated to the PCC forum at the earliest. 28. Emergency Load Disconnection Scheme during sustained over drawl at Low Frequency. During the previous PCC meetings, SRPC had approved the implementation of ALDS to trip the loads of the constituents which were over drawing. It was noted that SRPC in its 14th meeting held on 27th August 2010 had agreed to implement Automatic Load Disconnection Scheme for overdrawing constituents with the following relief: 22

24 Sl.No. Constituents Load Relief 1 APTRANSCO 450 MW 2 KPTCL 350 MW 3 KSEB 125 MW 4 TNEB 650 MW 5 Puducherry 25 MW KPTCL had earlier informed that 350 MW of load relief through remote tripping of load under crisis period has been identified. The same is under testing and final implementation stage and would be implemented shortly. It was noted that Puducherry had provided remote tripping facilities in the identified feeders in order to provide emergency disconnection. The is for the information of the PCC forum. 29. Providing synchronizing facility at Key Stations for black start restoration: The issue of providing synchronizing facility at Key stations for black start restoration was highlighted in the various SRPC forum meetings. The current status of synchronizing equipment installation at key stations is as follows: S.No Sync. facility requirement at Status station 1 Hubli To be provided during R & M works. However Bidnal station is having synchronous facility. Nagjhari can be synchronized at Bidnal and then supply can be extended to Hubli as a temporary arrangement. 2 Mahlingapura Will be commissioned in 3 months 3 Kayathar 110 kv Action being taken 4 Kadra, Kodasahalli Yet to be provided 23

25 All the Generators would have synchronization facility. The identified station would be provided with Synchronizing facility at the earliest. The status of provision of Synchronizing facility may be updated. 30. Protection aspects of Wind Turbines: The PCC forum had emphasized the need to examine and optimize the protection practices adopted for Wind Turbines as penetration levels are increasing. SRLDC vide Lr No SRLDC/SRC&S/Prot/2012 /4559 dt (item no 14) give the following agenda. On at 10:48Hrs one of the 110 KV wind pooling Station, 110 KV O-Tulukapatti station went dead due to CT Blast in 110kV Kayathar O- Tulukapatti Feeder Causing outage of about 500MW Wind Generation. SR Frequency Dipped from about 49.60Hz to 49.00Hz. There is a need to examine and optimize the protection practices adopted for Wind Turbines as well as protection at Wind Pooling stations as the penetration levels are increasing. Members may discuss the issue. 31. Voltage Control Relays as per IEGC. As per 5.2.(t) of System Security Aspect of Operating Code (Part -5) of IEGC, voltage control relays should be provided. The IEGC The Users, CTU and STUs shall provide adequate voltage control measures through voltage relays as finalized by RPC to prevent voltage collapse,and shall ensure its effective application to prevent voltage collapse/cascade tripping. Voltage Relays should be provided as per IEGC Guidelines. 24

26 The PCC forum recommended for feasibility study for provision of Voltage control relays in the following nodes i.e. at Somanahalli, Sriperumbudur, Kalavindapattu, Almatti, Mysore etc. In principle the forum had agreed to install the Voltage control Relays in the nodes after resorting to all measures of MVAR control and at lower settings so that phenomenon like load encroachment does not take place. The status of provision of under voltage relays as mandated in IEGC Regulations to control low voltages at the following 400 kv nodes: Sriperumbudur, Almathy, Chittoor, Nellore, Mysore, Somanahalli, Kalavindapattu, Trichur & Hosur may be intimated to the forum. 32. Review of Deliberations of 1 st Monitoring Committee meeting and other meetings of protection subcommittee. Members may please give updates with regard to the items discussed in the 1 st Monitoring committee meeting and the other meetings of protection subcommittee held during 14 th PCC and 15 th PCC. (i) Spl meeting of PCC held on Annexure IX (ii) Spl meeting of PCC held on Annexure IV,X (iii) Spl meeting of PCC held on Annexure XI (iv) 1 st Monitoring Committee of PCC held on Annexure XII 33. Date & venue of the next meeting. The next PCC meeting will be held in the month of October 2012.The exact date and venue shall be communicated in due course. 25

27 ANNEXURE I (Page 1 of 2) 1.Details of Grid Disturbances: S No Date & Time of Occurrence 3 rd April :02 Hrs 18 th April :23 Hrs 27 th April :45 Hrs Type GD1 GD1 GD1 Load loss or Generation loss Gen.Loss- 2200MW Load Loss MW Gen.Loss- 850MW Gen.Loss- 415MW Area(s) affected North coastal Karntaka and 400kV Guttur SS, 400kV Kaiga SS, 400kV Narendra and Nagjheri, Kodasalli, Kadra, Kaiga, Narendra, Hubli, Bidnal, Guttur and Ambewadi become dead. NeyveliTPS-2 400kV Sub station 400kV Guttur Substation Reason At 11:01 Hrs,due to a suspected momentary DC grounding of the isolator NO/NC contact wires running from individual bay bus selection isolator to 400kv bus bar protection relay panel, Bus bar protection relay operated at 400kV Guttur. At 09:23:39 Hrs, Due to internal fault in the B-phase SF6 CT of 400kV Neyveli-TPS- Pondy line, SF6 pressure has come down to zero and feeder got tripped. During the auto reclosing at 09:23:40 Hrs both the 400kV buses got cleared on Bus bar protection. Neyveli TPS 2 Stage II Units 4, 5, 6 & 7 went on house load and 400kV Neyveli TPS 2 buses (Double Main one Transfer Bus scheme) became dead. A Bus fault occurred at 400kV Guttur SS due to flashover of B- phase Lightening Arrester of 400kV Guttur-Hiriyur-2. Bus bar protection operated and all 400kV feeders got tripped along with 400/220kV ICTs. 2.Details of Grid incidents 1 220kV Bus-II cleared due to bus bar protection operation 220kV Bus-II at VTS Generating station got cleared due to Bus fault. The fault was created due to CT blast on 220kV VTS-Tadikonda-II feeder. Out of 6 units three units, Unit#2, 3&6, got tripped and there was a generation loss of about 600 MW. - -

28 ANNEXURE I (Page 2 of 2) 3) Talcher Kolar Pole Trippings S No Details of Event Date & Time Reason Kolar SPS Talcher SPS Remarks Talcher-Kolar Pole-1 tripped and Pole-2 came on Metallic Return mode. Power Flow came down from 2460MW to 387 MW. Frequency came down from Hz to 49.18Hz. Talcher-Kolar Pole- 1&2 tripped. Power Flow came down from 1970 MW to 0 MW. Frequency came down from Hz to 48.88Hz. Talcher-Kolar Pole-1 tripped and Pole-2 came on Ground Return mode. Power Flow came down from 1970MW to 147MW. Frequency came down from Hz to 49.16Hz. Talcher-Kolar Pole-2 tripped and Pole-1 came on Ground Return mode. Power Flow came down from 1970MW to 147MW. Frequency came down from Hz to 49.16Hz. Due to failure of 24 Volt DC power supply to pole control system due to short circuit in ATR OE4 card. Pole -1 & 2 tripped due to Commutation failure, which was happened due to R-phase CT blast of 220kV Somanahalli- HSR layout at Somanahalli end. 400/220kV Somanahalli ICT-1&2 Tripped on backup over current protection. Due to HVDC line fault at Location no 56, km from Talcher end. Due to HVDC line fault at Location no 57, km from Talcher end. Inter trip signal-1 generated SPS not operated Inter trip signal-1&2 generated Inter trip signal-1&2 generated Unit#5 and Unit#6 tripped Unit # 6 tripped and Generati on of Unit#4& 5 back down by 150 MW each. Unit # 6 tripped and Generati on of Unit#4& 5 back down by 150 MW each Unit # 6 tripped and Generati on of Unit#5 back down by 150 MW..

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