Southern Regional Lo... v. Director (Grid Opera...

This petition has been filed by the petitioner, Southern Regional Load Despatch Centre with the following prayers, namely:

“(a) Ensure Adequacy and healthiness of protection system in compliance with regulation 3(e) of the CEA (Grid Standards) in terms of IEGC regulation 5.2(e);

(b) Form their own expert group in protection audit for periodic protection audit of the entire substation of 220 kV and above on continuous basis and discuss such protection audit reports in the Protection Co-ordination subcommittee of SR;

(c) Ensure different type (Principle of operation) and make of relays for Main-I and Main-II protection as well as different input for different protection schemes in a time bound manner on priority;

(d) Ensure proper and periodical preventive maintenance of transmission lines including RoW clearance, bush/jungle cutting etc., particularly in forest area adopting best O&M Practices;

(e) Ensure dual source of supply for all the auxiliaries in substation;

(f) Ensure availability of bus sectionaliser scheme in all the 200kV/230kV substation that may lead to Grid disturbance of category GD-I and above;

(g) Ensure strict compliance of IEGC provision under clause 5.2(r) in furnishing the detailed tripping report along with DR & EL printouts within 24 hrs. of the occurrence of the event; and

(h) Pass such further Order as this Hon'ble Commission may deem just and proper in the circumstances of the case.”

2. The petitioner has submitted that from January, 2013, at least 16 times Grid disturbance of Category GD-I were occurred in Southern Region (SR) due to delayed operation or failure to operate of concerned protection relays/scheme, i.e improper functioning of Protection Schemes.

3. As per the recommendations of Enquiry Committee report, a third party protection audit in SR was carried out and all constituents were agreed in principle for implementation of the recommendations. However, the status review reveals that many recommended items are yet to be implemented. In addition, there were Grid Disturbance (GD-I) instances due to not complying with the best O and M practices by the concerned utilities. The petitioner has filed this petition seeking directions to respondents to ensure timely implementation of recommendations of Protection Audit.

4. The petitioner has enumerated details of events causing Grid disturbances as under

Event Time Description Reason Multiple tripping of 220 kV transmission lines at Madakathara sub-stations of KSEB 02.01.2013 at 13:58 hrs Resulted in complete outage of 220 kV this sub-stations and thereby loss of supply to parts of North Kerala. Default Fault Clearance in Madakatathara-Areacode 220 kV line breaker on (Y-B phase fault). Also there was no provision like bus sectionaliser in Madakathara sub-station Multiple tripping of 400 kV transmission lines at Hassan substation due to failure of CT of POWERGRID 10.03.2013 at 15:04:23 hrs. Led to outage of multiple elements connected to 400/220 kV Hassan substation. There were two faults and during both instances, there was delayed clearance of fault i.e, in 240 ms and 320 ms against 100 milli seconds Simultaneous forced outage of multiple transmission lines, interconnecting transformers and generating units in SR. 29.03.2013 at 13:48 hrs. Outage took place at Vijayawada TPS (APGENCO) and Koyhagudam TPS (APGENCO) in SR. Resulted in threat to integrated operation of SR Power System due to depleted transmission system resulted from wide spread tripping. There was slow developing fault in B-phase which took nearly 21 seconds to get cleared against the 100 milli second mandate of CEA Loss of about 700 MW wind generation in TamilNadu due to outage of 230/110 kV Kayathar substation of TANTRANSCO 07.06.2013 at 10:47 hrs. Resulted in sudden dip in frequency from 50.05 to 48.83 Hz. Occurred due to fault in 110 kV bus at 230/110 kV Kayathar substation. There was delayed clearance of fault. Time taken for clearance of fault was in seconds against mandate to 160 ms. Also there is no bus sectionaliser scheme at 230 kV as well as bus protection scheme at 110 kV bus of 230 kV Kayathar sub-station, though the sub-station is very critical pooling station of wind generation in Tamil-Nadu. GD-I category fault. Loss of generation 690 MW, in Karnataka system 08.01.2013 at 8:35 hrs. Total outage of Sharavati 220 kV sub-station. Due to delayed fault clearance GD-I category fault. 28.01.2013 Total outage of Due to delayed fault clearance Loss of generation 850 MW, in Karnataka system at 23:21 hrs. Sharavati 220 kV sub-stations GD-I category fault. Loss of generation 600 MW, in Karnataka system 13.06.2013 at 14:00 hrs. Total outage of Sharavati 220 kV sub-station. All running units at Sharavati hydro station also tripped. Due to delayed fault clearance. Report received from KPTCL and KPCL indicates fault had occurred in 220 kV Sharavati-Sirsi line 1 and 2. If protection system was in order, the fault would have been cleared at Sharavati end due to failure of both Main-I and Main-II protections. It can be inferred from PMU data that fault was cleared in 2.2 seconds against mandate of 160 ms by CEA.

5. The petitioner has submitted that the following measures have been taken by SRPC and SRLDC:

(a) Third party protection audit has been carried out at Sharavati Hydro station on 19.11.2012 and recommendations were submitted. Following critical observations were made by the audit team:

1. Only 1 CVT for all feeder protection

2. Same CT core is used for both Main-I and Main-II

3. Carrier protection not available for many feeders

4. Very old breakers (1964 make) in poor condition that served its life

5. DC earth leakage condition etc.

(b) On 6.3.2013, SRPC had constituted a task force committee to visit 220 kV Sharavati Hydro station to analyze the tripping on 8/28.1.2013 and to suggest remedial measures to prevent reoccurrence of the event. The committee reviewed the progress of protection audit recommendation and identified various other things to attend by Karnataka Power Corporation Limited/Karnataka Power Transmission Corporation Limited as under:

1. Dual battery source with dual rectifier

2. Replacement of old electro-mechanical relays with numerical relays

3. Replacement of Westinghouse make OCB bus sectionaliser breaker

4. Different energisation source for breaker trip coil and etc.

(c) Both reports have highlighted several inadequacies in respect of protection system at Sharavati Hydro station. Number of lapses have been observed in the reports and some even lead to non-conformity of CEA Grid Standards.

(d) As per Regulations 5.2(r) of Central Electricity Regulatory Commission (Indian Electricity Grid Code) Regulations, 2010 (Grid Code), all the regional entities are required to furnish tripping report in specific format along with Disturbance Recorder (DR) and Event Logger (EL) printouts within 24 hours of the event. However, there is significant delay in receiving detailed tripping report along with DR and EL print outs from SRLDC and SRPC. Till the completion of analysis and implementation of recommendations of SRLDC/SRPC, the system operator is exposed with the risk of operating the system without knowing the danger associated with those elements that caused the Grid disturbance. The delay in reporting also adds delay in implementation of required corrective/preventive measures.

(e) There were instances of Grid disturbance due to non-clearance of bushing/jungle clearance or non-trimming of tree branches within the RoW to transmission lines periodically. The instance of 13.6.2013 is a typical case of such nature. It is evident that there was no periodic patrolling of lines by KPTCL in certain portions that lead to unwarranted tripping of critical transmission elements.

(f) In all control area of SR Regional Entities, following instances were reported which are affecting the security, economy and efficiency of the entire power system in Southern Region and needs to addressed quickly:

(i) Inadequacies/failures in the protective system at sub-stations.

(ii) Lack of proper patrolling and jungle clearance

(iii) Improper time setting/relay coordination/delay in fault clearance

(iv) Malfunctioning of protection system, etc.

6. The petitioner has also filed Interlocutory Application No. 36/2013 seeking directions to respondents to comply with the Grid Code. The petitioner has submitted as under:

(a) All the Regional entities agreed in principle for implementation of the recommendations of the Protection Audit. However, the status Review reveals that many recommended items are yet to be implemented.

(b) On 15.7.2013 at 21:47:11 hrs., complete outrage of 400 kV Nellore Pooling Station of Power Grid along with generation loss of 260 MW had occurred at Simhapuri Energy Limited (SEL) and 139 MW at Meenakshi Energy Private Limited (MEPL).

(c) On 3.8.2013 at 05:26 hrs., all connected lines and ICT's tripped at 400/220kV Mamedapalli (Hyderabad) sub-station of APTRANSCO. The triggering incident was failure of R-phase current transformer in 400kV Khammam line-1 Main bay and failure of B-phase bus post insulator in Srisailam-2 Main bay at Mamidapalli sub-station.

(d) On 2.9.013 at 11:41 hrs., all connected 220 kV lines, 400kV Kaiga-II and ICT-I and II tripped at Guttur sub-station. The synchrophasor data indicates that there was a fault in B-phase and there was a delayed clearance of fault.

(e) On 10.9.2013 at 3:04 hrs., multiple tripping had occurred at 400/220kV Nellore sub-station of Powergrid. The following lines had tripped on operation of over-voltage stage-1 protection and there was generation loss of 260 MW occurred at Simhapuri power station and 220 MW at Meenakshi power station due to loss of evacuating lines:

Name of line/equipment Date of tripping Time of tripping 400kV Nellore pooling-Nellore line-1 10-09-2013 2:46 400kV Nellore pooling-Nellore line-2 10-09-2013 3:04 400 kV Vijayawada — Nellore line - 1 10-09-2013 3:04 400 kV Vijayawada — Nellore line - 2 10-09-2013 3:04 400kV Nellore — Sriperambadur line 10-09-2013 3:04 400kV Nellore - Almathi line 10-09-2013 3:04 400 kV Krishnapatham — Nellore (A.P) line — 1 10-09-2013 3:04

As reported, 400 kV lines connected to Nellore had tripped on operation of over voltage stage-1 protection. The 400 kV bus voltage (figure-1) from synchrophasor at Gooty indicates a high voltage. It can also be inferred that there was no fault in the system prior to the multiple tripping.

(f) SRPC and SRLDC have taken all possible efforts to identify the slackness in SR protection system through protection audit and circulated audit observation to all the regional entities for immediate action. Also, the events occurred during the month were analyzed in details and discussed in the following Protection Coordination Committee (PCC) meetings of SRPC for suitable corrective action.

(g) It may be evident from the details of all the above incidents, that there is substantial delay in implementation of recommendations of the protection audit and task force committee reports of various incidents by all the regional entities. There is lack of pro-active action by the Regional Entities due to the reasons like inadequate man power, additional financial implication, delay in procurement process etc. Despite SRLDC repeatedly follows-up and takes-up in forums like PCC and OCC for getting the DR, EL, and other details of tripping instances, there is significant delay in receiving such essential data for doing timely analysis.

7. Replies to the petition as well as IA have been filed by the Karnataka Power Corporation Ltd. (KPCL), SLDC Karnataka, TANTRANSCO, NTPC, Kerala State Electricity Board and APTRANSCO.

8. Karnataka Power Corporation Ltd. (KPCL) in its reply dated 28.9.2013 has submitted as under:

(a) According to the petitioner, Sharavati units 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10 tripped due to which generation loss of 690 MW and frequency came down from 50.05 Hz. to 49.49 Hz. KPCL has submitted that it was reported on 8.1.2013 at 8:37 hrs., generator voltage reduced from 11 kV to zero causing station blackout. The reason for this might be failure of control supply of Governor and AVR, which in turn indicates that the root cause as 250V station battery bank, which is unusual to its nature. However, immediately after the station blackout, DG was started and the station was normalized and units brought on bar after 45 mins.

(b) In SGS, there are two battery banks of 1000 AH and 500 AH. Standard O&M practices are being carried out in the corporation for regular maintenance of batteries as under:

(i) Pilot cell readings of the battery banks are noted down daily;

(ii) Weekly/fortnightly cleaning of the battery banks and application of petroleum jelly;

(iii) Monthly topping up of distilled water for maintaining the electrolyte level and boost charging of the battery bank if required.

(c) Action had taken by replacing the new battery bank (1000AH) commissioned and taken into service on 16.1.2013

(d) With regard to tripping of Sharavati Units: 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10 on Earth Fault protection at 28.1.2013 at 23.21 hrs., Chief Engineer, Sharavati, KPC on 29.1.2013 have furnished the detailed report pertaining to system disturbance on 28.1.2013 to SRLDC which was discussed and recorded in minutes of 17th meeting of Protection Coordination Sub Committee held on 26.2.2013 at SRPC, Bangalore. On 28.1.2013, it was reported that, Sharavati-Talaguppa (St-1) line was taken on bus coupler breaker to review the settings of Main-I and Main-II relays of ST-1 line.

(e) At 23:20 hrs., ST-1 and ST-2 lines tripped at Talaguppa end only. ST-2 line tripped on backup zone-3 fault at Talaguppa and ST-1 tripped on back-up earth fault at Talaguppa end and ST-1 tripped on backup earth fault at Talaguppa end only. Rest of line breakers hand tripped after the station bus became dead.

(f) At 00:25 hrs on 29.1.2013, it was informed by Talaguppa AEE that ST-1 and ST-2 tripped at their end only on earth fault during the event. At 1:42 hrs., ST-2 line taken into service and at 02:00 hrs., ST-1 line, which was on bus coupler breaker was changed over to regular breaker. At 02:07 hrs., St-1 again tripped on distance fault (Zone-1) when tried to take into service. After line patrolling TLM staff of KPTCL informed that de-capping/flashover of R-phase line insulator at location no. 8 has occurred and caused the disturbance for which distance relays may not detect on zonal fault, whereas backup relays should operate to these type of faults. However, the bus coupler breaker (taken on St-1) at SGS end did not trip on Back-up E/F.

(g) To analyze and investigate the events, on 30.1.2013, team from RT, KPTCL, Shimoga tested the bus coupler relays and informed that the relay is operating for distance zonal settings whereas the configured output relay for backup E/F settings is not operating for Main-I and II relays. The output relay was reconfigured, tested and normalized.

(h) On the issue of Sharavati-Sirsi line:—

(i) On 13.6.2013, it was reported that SS-1 line tripped on distance protection at both the ends. Subsequently, units on bar 1, 2, 3, 6, 7 and 8 tripped resulting in station shutdown. Rest of the lines were hand tripped. Auxiliary supply resumed through DG set and subsequently, units started from 14:40 hrs.

(ii) It was informed by KPTCL TLM staff that a bamboo branch had fallen on Sharavati Sirsi line-1, SharavatiSirsi line-2 causing phase to ground faults and R-Y phase fault, which was cleared. Thereafter, and lines were restored at 16:20 hrs.

(iii) SS-1 line tripped on fault at both ends. SS-2 line tripped at Sirsi end on distance protection. However, relays of SS-2 line at SS end (ABB make REL511) found not operated. Since SS-2 line did not trip on fault, all the running generators tripped on back-up earth fault and remaining lines tripped at other end occurred on 13.6.2013 to SLDC and SRPC.

(iv) Remedial Solution: ABB's representative, OEM of the relay was called to visit the site to check the functions of relays on 17.6.2013, the representative of ABB visited SGS for checking of relays and it was found that the terminal configuration of the relays was not properly downloaded earlier and suspected some files were missing. Original files were downloaded and all the functions were tested and found working satisfactorily.

(i) On the issue of Kodasalli Hydro Power station tripping, shutdown was taken for 220 kV Kodasalli-Nagjhari line-2 on 16.6.2013 at 12:05 hrs., during the testing, the local breaker back-up relay of 220 kV Kodasalli-Nagjhari line-2 maloperated unexpectedly which in turn led to tripping of 220 kV bus at Kodasalli Hydro Station.

Remedial Solution: The relay was serviced and tested and found satisfactorily.

(j) Since SS-1 line tripped and cleared the fault in 40ms, the operation of the SS-1 distance relay is consistent as per requirement and CEA norms and fault on SS-2 line persisted.

(k) On the reasons of both the Main-I and Main-II protection of 220 kV Sharavati-Sirsi line-2 failed operation, it is clarified that the relays were calibrated by KPTCL staff on 4.3.2013 However, the relays did not respond. On thorough checking of the relays by firms, it was found that the terminal configuration of the relays was not properly downloaded earlier and suspected files were missing. The problem was rectified and relays were tested and found to be in order.

(l) With regard to only 1 CVT is there for all the feeder protection, KPCL has submitted that as per normal practice, one or two CVT's output was usually used for feeder protection. However, as desired by SRPC, the matter of providing CVT's for all the 3 phases of lines has been deliberated at higher levels and included in DPR for Renovation and up gradation of Control and Protection system for 220/400 kV Switchyards of KPCL Generating Stations”, which has been furnished to SRPC.

(m) With respect to same CT core being used for both Main-I and Main-II, KPCL has submitted that as per earlier practice there was only Main-1 distance protection for 220 kV lines. Due to interaction, pursuance for implementing Main-2 protection by SRPC to 220 kV feeders also, Main-2 protection was provided at the same core. This has not caused any grid events from past decades. As per guidelines of CEA, Main-1 and Main-2 are required for 400 kV lines and Main-1 is required for 220 kV lines and Main-2 is optional i.e “yes/no” (shown in CEA's gazette Page No. 121 schedule-V). However, as desired by SRPC, the issue of replacement of CT's by 5 core Ct's has been deliberated at high levels and finally approval sought for including in the DPR furnished to SRPC.

(n) With regards to carrier protection not available for many feeders, it has been submitted that carrier protection is provided for all the feeders. (SS-1 and SS-2 feeder wave trap was not available during audit. The same was normalized by KPTCL later).

(o) With regard to very old breakers (1964 make) in poor condition, KPCL has submitted that this in context to Sectionaliser Breaker referred by the Audit team. As sectionaliser breakers are of BOCB type with built in CT's and also due to space constraint in the switchyard, BOCB's of sectionaliser breaker could not be replaced by SF6 breakers (as CT's and breakers are to be mounted separately). Now it is proposed to replace Sectionaliser breaker of BOCB type by modern hybrid breakers with built-in CT's and isolators already included in the DPR furnished to SRPC.

(p) With regard to DC earth leakage, it has been submitted that occurrence of DC earth leakage is not regular phenomenon. The problem is being rectified when it occurs. This is the duty of routine maintenance staff and the problem may appear rarely, especially during rainy season.

(q) Regarding dual battery source with dual rectifier KPCL has submitted that dual battery source is already commissioned (1000AH-16.1.2013 and 500Ah-24.6.2013)

(r) Regarding replacement of old electro-mechanical relays with numerical relays, KPCL has stated that this is in context with bus bar protection system. The work was already awarded to GE India Ind. Pvt. Ltd. Bangalore on 22.3.2007 Supply of the new numerical bus-bar protection panels with relays completed. While supplying the cables, the contractor had delivered cable short length which was not suitable to works. The problem has been rectified and work is in progress.

(s) Replacement of Westinghouse make OCB Bus sectionaliser Breaker is included in DPR.

(t) Regarding different energisation source for breaker trip coil and tec., KPCL has submitted that dual battery source is already commissioned (1000AH-16.1.2013 and 500AH-24.6.2013)

9. Karnataka Power Transmission Corporation Limited and State Load Despatch Centre, Karnataka vide their joint reply dated 20.11.2013 have submitted as under:

(a) On the issue of ensuring adequacy and healthiness of protection system the protection system adopted for 220 kV and 400 kV networks and the setting adopted for these protection relays are based on CBIP guidelines and the directions of SRPC.

(b) On the issue of formation of own expert protection audit group, SRPC has formulated a third party protection audit group which audited KPTCL from 11.10.2012 to 22.12.2012 The observations of the audit team were discussed in SRPC meeting and minor observations were attended. However, regarding major observations, DPR is already prepared which is under execution.

(c) KPTCL has formed 4 RT circles with Superintending Engineers as head of the circle and 14 RT divisions for effective periodical testing and up keeping of protection system. Further, based on the fault level and system conditions, relay coordination is carried out during pre-commissioning only.

(d) On the issue of ensuring different type and make of relays for Main-I and Main-II protection, it has provided 2 main numerical distance protection for all 400 kV lines. 220 kV lines were provided with one distance protection and OCRs and EFR for the backup protection as per the prevailing practice.

(e) The issues raised in I.A have been discussed in Protection Committee meeting of SRPC and the recommendations of SRPC/SRLDC are implemented. Necessary remedial measures are taken, if required.

10. TANTRANSCO in its reply dated 6.11.2013 has submitted that adequacy and health of Standard Protection System is up to date. Monthly report on the healthiness of the protection and availability is sent to SRPC regularly. Further, the fault clearance time for all equipments is well within 100 msecond and the breaker fail protection is also set to operate 200 ms as per Regulation. TANTRANSCO has stated that a DPR specifying the requirement of materials and connected works to comply with the recommendations of Task Force including recommendations of Protection audit through SRPC in all 230 KV and above level sub-station is under process of implementation. TANTRANSCO has requested SRPC to provide financial assistance from PSDF. According to TANTRANSCO, protection audit of 33 sub-stations have been completed and minor issues recommended by audit team have been resolved. All efforts are being taken to comply with the directions and recommendations of SRPC.

11. NTPC vide its reply dated 14.11.2013 has submitted that it is complying with all directions of the petitioner and SRPC. NTPC has further submitted that directions in respect of Ramagundam STPS and Simhadri STPS have been complied with.

12. Kerala State Electricity Board (KSEB) in its reply dated 6.11.2013 has submitted that all necessary steps are being taken for implementation of the recommendations of the enquiry committee report. Protection audit has already been completed in all 23 Nos. 220 kV and one No. 400 kV sub-station and on 15.6.2013 DPR prepared based on the protection audit was submitted to SRPC. KSEB has submitted that since the work associated with protection audit has to be executed through various departmental procedures, four months time is not sufficient to implement recommendation of protection audit. KSEB has submitted that on 2.1.2013 at 13.59 hrs., MDAR tipped on distance protection zone I, B and C phase, LBB, reclosed and A/R lock out 315 MVA transformer Bank I (220 kV side) 200 MVA transformer bank II (220 side) SHMD, MDPK and LMPD II 200 kV feeders tripped on LBB, which is a mal-operation. Tripping of MDAR feeder on distance protection (zone I, B and C phases) was normal. Available records or data did not reveal for LBB tripping. However, circuit breaker and relays were tested and proper functioning has been ensured KSEB has submitted that DR and EL in major sub-stations and generating station. However, routine tests are being done to confirm proper functionality of various protection schemes and non-occurrence of mal-operation.

13. APTRANSCO and SLDC, APTRANSCO in their joint reply 22.10.2013 to IA has submitted as under:

(a) On 3.8.2013 at 5.26 hrs., all concerned lines and ICTS tripped at 400/220 kV Mamidapally (Hyderabad) sub-station of APTRANSCO due to the failure of R-phase current transformer of 400 kV Khammam line-I Main bay and failure of B-phase bus post insulator in Srisailam-II Main bay at Mamidapally sub-station. The fault was rectified in 120 msec.

(b) In 23rd Protection Coordination Sub-Committee meeting held on 27.8.2013, a decision was taken to adopt the delay operation of CT supervision relay as 3 to 5 seconds against the existing default setting. Accordingly, on 24.9.2013 setting was revised from the existing 1.09 seconds operation to 5 seconds.

(c) The protection audit in APTRANSCO was carried out at 11 Nos. and 18 Nos. 400 kV and 220 kV sub-stations respectively and certain recommendations were made involving the activities both immediate rectifications, Renovation and Modernization.

(d) Certain critical and innovation measures, such as planning of islanding scheme and implementation of SPS etc. were taken.

(e) APTRANSCO is adopting the defensive mechanism for achieving the frequency stability by providing the load relief through under frequency relays and F+df/dt relays methods and their periodical testing are being carried out and same is communicated to SRPC.

(f) FIRs and details reports of all sub-stations are regularly submitted to SRPC and SRLDC subject to availability of Disturbance Recorders and Event Loggers.

(g) APTRANSCO has requested to provide financial support from PSDF fund for the renovation and modernization activities.

14. TANTRANSCO vide its affidavit dated 1.2.2014 has submitted that all the Special Protection Schemes recommended by SRPC are implemented and compliance report sent to SRPC and SRLDC. The process of procurement of critical items and supply by the vendor require 4 months time and the commissioning would require another 2 months time. The implementation of Phase-I activities would be completed within six months.

15. The petitioner has vide its affidavit dated 8.1.2.014 has filed rejoinders to replies of KPCL, KPTCL, TANTRANSCO, NTPC and APTRANSCO. In response to KPCL reply, the petitioner has submitted as under:

(a) It is to be noted that:

(i) GD-I dated 8.8.2013 was due to failure of Aux Supply/defective battery bank;

(ii) GD-I dated 28.8.2013 was due to non-operation of breaker at Sharavati end;

(iii) GD-I dated 13.6.2013 was due to delayed fault clearance of fault on 220kV Sharavati-Sirsi line at Sharavati end;

(iv) GD-I dated 17.6.2013 was due to miss-operation of LBB relay of 220 kV Kodasalli — Nagjhari line-2.

Though all the above GD-1 type grid disturbances are due to either failure/miss-operation of sub-station equipment, protection relays and switching elements, the respondent's claim that the maintenance activities/testing/calibration was done as per the industry standard is not justifiable.

(b) KPCL has also linked number items with funding modality through DPR such as replacement of CT core for Main-I and Main-II, replacement of Westinghouse make OCV Bus sectionaliser breaker, replacement of sectionaliser breaker of BOCB type with modern Hybrid breakers etc. have been linked to the DPR or the funding modality. It is pertinent to mention that respondent is aware of the replacement required in its system even before the protection audit. Instead of attending the same on priority, the respondent links with funding modality thereby deliberately exposing the system to security threat for longer duration.

(c) While admitting the pitfalls indicated in protection system at KPCL stations, the action plan indicated by KPCL for rectification/replacement does not match the urgency as it is required. From the time schedule mentioned by KPCL, it appears that the procurement action is being taken as applicable for a routine item without any due urgency on the criticality of protection system. For some of the items, even time schedule for implementation is not mentioned. Accordingly, the grid is exposed to security threat for longer duration/till the implementation of identified rectification/replacement. For example in reply to the Petition, for the replacement of old electro-mechanical relays with numerical relays, the work is said to be in progress. In the reply to the Interim Application, for installation of DC earth fault relay, 4 months, commissioning of numerical bus bar protection system 6 months, is sought and for procurement of unique Disturbance Recorder for the whole facility, procurement of GPS facility, no timeline is provided. From the above, it is evident that KPCL adopts normal procurement procedure even for highly critical protection items. This nature adopting routine approach, poses severe threat to grid security for the integrated operation of SR with NEW grid. The impact of the problems in Karantaka system on the inter regional inter connector is very high as at present SR grid is connected through only one 765 kV ISTS line emanating from Karnataka system.

16. The petitioner, in response to KPTCL reply, has submitted as under:

(a) KPTCL has submitted that it has provided two different protections for Main and back-up. However, the concern of the petitioner is that in many locations the relays are of same make though they are configured on different logic/principle. Under this situation, in case of any defect in configuration/software of the relays of same make, the effect will be the same on both Main as well as backup protection. The right approach to mitigate such a failure is to have relays of different make for Main-I and Main-II protection respectively. This aspect was deliberated in PCC meetings and special meetings in which the constituents including KPTCL endorsed the requirement. Accordingly, necessary action needs to be ensured by KPTCL.

(b) The transmission line maintenance procedure is fairly followed in most of the area. The maintenance activities in hardship terrain and forest area are the matter of concern which makes such locations as fault prone.

(c) If the healthiness of the protection system would have been ensured properly, number of the instances enumerated in the petition could have been averted. Probably deployment of expert team with adequate number of members for rigorous and periodic checking by the respective constituents is essential for this activity.

17. The petitioner, in response to TANTRANSCO reply, has submitted as under:

(a) TANTRANSCO has stated that the fault clearance time by the main protection for all equipments is well within 100 m. sec. However, the experience of incident at Kayathar on 7.6.2013 confirms that the time taken for fault clearance was about 1.5 seconds while the Central Electricity Authority (Grid Standards) Regulations, 2010 prescribes 160 milliseconds as maximum fault clearance time for 230 kV system.

(b) It is reiterated that the loss of wind generation led to heavy drawl from grid by Tamil Nadu which in turn resulted in sudden dip in Southern regional grid frequency from 50.05 to 48.83 Hz. The Commission in its order dated 21.8.2009 in Petition No. 106/2009 had directed TANTRANSCO to implement suitable contingency plan on demand side management to offset the impact of sudden loss of wind generation. However, TANTRANSCO has not complied with the Commission's direction despite regular monitoring by SRLDC and SPRC.

(c) TANTRANSCO has alleged that adequacy and health of the standard protection system of TANTRANSCO feeders, Auto Transformers and Bus Bar protection scheme for 230 kV and above level are up to date in TANTRANSCO network. It is pointed out that outage of 230/110 kV Kayathar sub-station of TANTRANSCO had occurred due to fault in 110 kV bus at 230/110 kV Kayathar sub-station. There was delayed clearance of fault as inferred from data of phasor measurement unit. Further, no visible measures have been taken by TANTRANSCO to install bus sectionaliser scheme at 230kV as well as bus bar protection scheme at 110 kV bus of 230 kV Kayathar sub-station.

(d) It has been pointed out in the Protection Audit that for Phase I, at 230 kV Kayathar sub-station, earth resistance had to be measured and recorded, and for Phase II renovation of control room needs to be done and proper fire fighting and oil drain pit to be provided for transformers. However, no response has been received on this front of the steps taken.

18. The petitioner, in response to NTPC reply, has submitted that as per the Protection Audit, while in Simadhri sub-station existing MICROMHO relays of Stage-I lines have been replaced with numerical relays.

19. The petitioner, in response to APTRANSCO submissions, has submitted that in the present petition, it has raised concerned on a grid disturbance of type GD-I occurred on 3.8.2013 with regard to lapses in protection system. However, such instances could have been averted provided APTRANSCO regularly analyzed the past incidents and revised the protection settings time to time in line with the changes in the transmission network configuration. With regard to rectifications, the petitioner has submitted that APTRANSCO attended items that generally does not involve financial implications. However, number of other critical items were kept pending linking funding modality. The petitioner has further submitted that the purpose of Islanding, SPS and AUFR are different from system protection and no one type can substitute the function of other. Accordingly, the requirement of effective and efficient system protection cannot be deferred with complacent that other mechanisms are in service. According the petitioner, since APTRANSCO confirms that some of the major stations are not equipped with Disturbance Recorders and Event Loggers, it will not possible for SRLDC and APTRANSCO to analyze the grid incidents/grid disturbances and make good the defects noticed. Therefore, situation amounts to non-compliance of Regulation 4.6.3 of the Grid Code.

20. The petitioner vide its affidavit dated 8.1.2014 has further submitted that considering the present status of Southern Regional Grid, it is very much essential to have perfect protection system in place and pro-active and proper maintenance in place of planning to attend the defect as and when it surfaces. The petitioner has further submitted as under:

(a) In the Southern Region, the situation is worrying with repeated or reoccurrence of multiple tripping leading to total black-out of 400kV/220kV substations due to mal-operation of the protection system at many locations.

(b) The condition of switching equipments in old 220 kV and 132kV substations is far below the standard.

(c) The protection requirements like auxiliary power supply, DC supply/batteries are under poor maintenance condition without complying reliability requirement.

(d) In new sub-stations or LILO sub-stations, the relay settings are not properly co-ordinated with the neighborhood sub-stations.

(e) At times features such as auto re-closure, relay reach etc., were not tested/ensured properly. Such lapses also pose threat with multiple tripping

(f) Constituents are not furnishing the trip report within 24 hours in terms of Regulation 5.2(r) of the Grid Code.

(g) Number of critical sub-stations such as Kayathar, Madakathara etc., continue to operate as single main and transfer bus configuration without any bus sectionaliser breaker posing threat of total outage of the sub-station in case of operation of bus-bar protection for any reason. The bus coupler breaker at Gummidipundi, Sharawathi, Madakathara, Guttur etc. are non-functional.

(h) The situation is not limited to any one constituent though the degree of issue varies. Some of the sub-stations at following locations are identified with critical lapses:

(i) Sharawathi, Nagjeri, Guttur etc., in Karnataka system

(ii) KTPS, Vijayawada, Srisailam etc., in AP system

(iii) Eadaman in Kerala System

(iv) Kayathar in Tamilnadu system

(i) O&M practices followed in transmission line maintenance (like Bush/Jungle clearance) in tough terrain/forest area are not planned properly by the constituents and thereby leading to persistent fault condition.

21. The petitioner has further submitted that all the above facts as well as number of lapses existing in the Southern Regional grid were brought out clearly in the Protection Audit Report with suitable action required to be done by the constituents. All the constituents endorsed the lapses and agreed in-principle for attending the same. However, the progress of implementation is insignificant. The matter has been regularly taken-up with Protection co-ordination Committee (PCC) meetings, OCC meetings, and Special meetings of SRPC. The seriousness of the issue has been brought to the senior management of the constituents through TCC and SRPC Board meetings. Since the constituents still rely upon the implementation with funding from PSDF, the implementation is getting delayed.

22. During the course of hearing on 19.12.2013, the Commission took serious note of the deficiencies pointed out by the petitioner and observed that the matter assumes added importance as NEW Grid is to be shortly synchronized with the Southern Grid. The Commission directed the petitioner to analyze as to whether Southern Grid can be connected synchronously with NEW Grid under such deficiencies. The petitioner was directed to file a list of detailed deficiencies in the systems of respondents and the respondents were directed to file an affidavit stating the deadline for attending to the deficiencies. The Commission also noted that the petitioner raised issue of noncompliance of the Regulation 5.2(r) of the Grid Code which mandated all users to report the disturbance/fault to RLDCs within 24 hours of occurrence. The Commission directed the petitioner to submit the instances of non-compliance by SLDC/users.

23. In response, the petitioner vide its affidavit dated 8.1.2014 has submitted as under:

(a) Any grid disturbance of Type GD-1 or above in SR may lead to operation of SPS/tripping of 765 kV Raichur-Sholapur inter-connector with sudden in-rush on either direction. The threat of dis-integration of SR grid from N-E-W grid is very high in the present scenario as the integration has been done using the available single inter connecting line. On 2.1.2014, the load changeover of huge quantum lead to in-rush of power through inter-connecting Raichur-Sholapur 765 kV line and SPS did not operate resulting in dis-integration. Also, operation of SPS with tripping of identified generating unit at WR and loads at SR happened twice within a couple of days of synchronization. If by any chance, these instances could have happened with simultaneous GD-1 incident, the result could have been catastrophic failure. Therefore, it is most important to have an effective protection system in service ensuring intended performance.

(b) With regards to protection deficiencies identified during protection audit of SR and other recommendations of PCC sub-committee of SRPC and prioritized the requirements in to two groups for implementation by the concerned Regional Entities as Phase-I and Phase-II activities in a time bound manner, the phase-I activities are such activities to be implemented without waiting for funding modality as well as following urgency clause. procedure for procurement items and the normal tendering process. In general, phase-I activities include revision of settings, replacement of numerical relays, implementation of bus-bar protection in critical 220kV sub-stations etc., while phase-II activities include replacement of defective/very old breakers, isolators, bus sectionliser, etc., at critical sub-stations. Phase-I items are to be attended in the shortest possible time, i.e within three months while the phase - II items needs to be attended at the earliest possible. The detailed list on constituent-wise are enclosed as Annexures — IA and IB respectively with this order.

(c) There are many tripping instances for which the tripping report, DR and EL print outs are yet to be received or received in a delayed manner. In the absence of timely receipt of such details/data, it may not be possible for the petitioner to analyse the incident immediately and come out with suggestions to avert such instances in future. Not maintaining DR and EL in proper working condition, nonavailability of qualified/adequate personal etc., could have been some of the reasons for non-furnishing of tripping details/report on time. The petitioner has filed the list of delayed receipt or non-receipt of tripping details/data as on date with its reply.

Analysis and Decision

24. We have considered the submissions of petitioner and respondents. It is clarified that grid security and operation within the prescribed parameters is of prime importance and no compromise will be allowed in this regard. The Commission considers it to be of paramount importance in view of the fact that two major grid disturbances occurred on 30/31.7.2012. Further, grid security assumes added importance as NEW Grid has been synchronously connected with SR Grid and there is one synchronous grid in the country with conventional generation of about 200 GW.

25. In the Central Electricity Authority (Grid Standards) Regulations, 2010 (CEA Grid Standards), ‘GD-1 type grid disturbance’ has been defined as under:

“Category GD-1 - When less than ten per cent of the antecedent generation or load in a regional grid is lost;”

26. The petitioner, after analyzing the system conditions, has submitted that any grid disturbance of ‘Type GD-1’ or above in SR may lead to operation of SPS/tripping of 765 kV Raichur-Sholapur inter-connector with sudden in rush on either direction, which means that the threat of disintegration in present system conditions is very high.

27. We agree to the petitioner's contention that the linking implementation of protection audit/PCC recommendations with funding modality has resulted into implementing schedule becoming uncertain which is undesirable as the matter involves grid security. The petitioner has proposed to segregate the works of implementation in two Phases, namely Phase-I requiring immediate attention and Phase-II requiring timely implementation. Phase-I involves minor works such as revision of settings, replacement of numerical relays, implementation of bus-bar protection in critical 220 kV sub-stations etc. and Phase-II involves activities such as replacement of old breakers etc. which may require some time. Accordingly, we direct the respondents to implement the works as mentioned in Phase-I and Phase-II by 1.5.2014 and 1.9.2014 respectively. SRPC is directed to co-ordinate the protection setting issue and submit a report regarding implementation of Phase-I activities by 1.6.2014 SRPC is further directed to submit bimonthly status report for works mentioned in Phase-II to the Commission.

28. In terms of Regulation 5.2(r), all the users, STU/SLDC and CTU are required to send information/data to RLDC within 24 hours for analysis of grid disturbance. Regulation 5.2(r) of the Grid Code extracts as under:

“5.2(r). All the Users, STU/SLDC and CTU shall send information/data including disturbance recorder/sequential event recorder output to RLDC within 24 hours for purpose of analysis of any grid disturbance/event. No User, SLDC/STU or CTU shall block any data/information required by the RLDC and RPC for maintaining reliability and security of the grid and for analysis of an event.”

29. The petitioner has submitted that number of respondents are not complying with the provisions of Regulation 5.2(r) of the Grid Code and the directions of the Commission. We administer a strong warning to the respondents to take all possible measures permissible under the Act and the Grid Code to provide data/information to RLDC and RPC for maintaining reliability and security of the grid. We also make it clear that failure in this regard will amount to non-compliance of the directions of this Commission and render the constituent liable for proceedings under Section 142 of the Electricity Act, 2003 and other relevant provisions. We also direct the petitioner and SRPC to co-ordinate and monitor the progress and compliance of Commission's directions and ensure compliance of Regulations 5.2(r) of the Grid Code and report instances of non-compliance to the Commission.

30. The petitioner has submitted that the respondents have not fully implemented the recommendations made by the Protection Audit Committee and Committee constituted by SRPC. This issue will be dealt with in order in Petition No. 220.MP/2012.

31. The petitioner has further raised issue of non-compliance of Regulation 3(1)(e) of the CEA Grid Standards and Regulation 5.2(e) of the Grid Code. Regulation 3(1)(e) of the CEA Grid Standards provides as under:

“3. Standards for Operation and Maintenance of Transmission Lines.

(1) All Entities, Appropriate Load Despatch Centres and Regional Power Committees, for the purpose of maintaining the Grid Standards for operation and maintenance of transmission lines, shall, …

(e) Provide standard protection systems having the reliability, selectivity, speed and sensitivity to isolate the faulty equipment and protect all components from any type of faults, within the specified fault clearance time and shall provide protection coordination as specified by the Regional Power Committee.

Explanation: For the purpose of this regulation “fault clearance time” means the maximum fault clearance time are as specified in Table below-

S. No. Nominal System Voltage (kV rms) Maximum Time (in milliseconds) 1 765 and 400 100 2 220 and 132 160

Provided that in the event of fault by a circuit breaker within the time limit specified in Table 4, the breaker fail protection shall initiate tripping of all the breakers in the concerned bus section to clear the fault in the next 200 milliseconds.”

32. Further Regulation 5.2(e) of the Grid Code provides as under:

“5.2(e) Maintenance of their respective power system elements shall be carried out by users, STUs and CTU in accordance with the provisions in Central Electricity Authority (Grid Standards) Regulations, 2010. Any prolonged outage of power system elements of any User/CTU/STU, which is causing or likely to cause danger to the grid or sub-optimal operation of the grid shall regularly be monitored by RLDC. RLDC shall report such outages to RPC. RPC shall finalise action plan and give instructions to restore such elements in a specified time period.”

33. The petitioner has submitted that there have been instances where fault clearance time has been more than the prescribed limit due to old equipment in the sub-stations. In this regard, the petitioner should take immediate steps. We direct the respondents to strictly comply with the provisions of Regulation 5.2(e) of the Grid Code and CEA Grid Standards. The petitioner is directed to monitor the progress and compliance of the Commission's directions and ensure compliance of provision of regulations. In case of non-compliance for action plan finalized by RPC, the petitioner is at liberty to approach the Commission with specific instances of non-compliance against defaulting entities for necessary directions in accordance with law.

34. The respondents are also directed to ensure proper maintenance of transmission lines and adopt best O&M practices.

35. The petitioner has raised another issue of Jungle Clearance and non-monitoring of transmission lines by patrolling. Trimming of vegetation below transmission lines is an important maintenance activity. In the United States, a major grid disturbance was caused due to non-cutting/trimming of trees of vegetation below High Voltage transmission line in Ohio in August, 2003. On this issue, we direct all RPCs to formulate patrolling protocol/guidelines by 1.6.2014 The protocol must also take into account the terrain, forest cover and reach in that area and ensure regular monitoring as per requirement in that area to ensure efficient operation.

36. We observe that Protection Co-ordination Committee functions under RPC. The petitioner is directed to discuss and try to resolve the issues in the Protection Coordination Committee and in case of non-resolution of the issues in RPC forum, the petitioner is at liberty to approach the Commission for direction/decision in accordance with law. The issues regarding non-compliance with the provisions of the Act and Regulations should be brought before the Commission and the implementation issues shall be handled at RPC level. Further, RPCs shall direct constituents to implement its recommendations in a time bound manner.

37. The petition No. 146.MP/2013 along with IA is disposed of with the above.