BLACK START AND RESTORATION PROCEDURES OF NER GRID

Transcription

1 BLACK START AND RESTORATION PROCEDURES OF NER GRID 7 th REVISION Month : Feb 2012 POWER SYSTEM OPERATION CORPORATION LTD (A wholly owned subsidiary of POWERGRID) NORTH EASTERN REGIONAL LOAD DESPATCH CENTRE SHILLONG Page 1 of 74

2 BLACK START AND RESTORATION PROCEDURES OF NER GRID Checked by: Sh. Anupam Kumar, Engineer, NERLDC Doc. Code: NERLDC/SO/ MANUAL Verifed by Reviewed by Approved by: Prepared and Issued by: Sh.B.Medhi, Sr.Engineer, NERLDC Sh.N.R.Paul, DGM(SO), NERLDC Sh.T.S.Singh, AGM, NERLDC Sh. B.Medhi Sr.Engineer, NERLDC CLASSIFICATION : OPEN Page 2 of 74

3 CONTENTS Sl No Chapter : Page No 1 Black Start Facility 4 2 System Restoration Approach 6 3 Power Map of NER 11 4 Network Diagram of NER 12 5 Broad classification of NER Grid 13 6 Black Start & Restoration Procedures : 25 Restoration of NER Grid after total collapse, when power from ER is available Restoration of NER Grid after total collapse, when power from ER is not available Restoration of 132 kv Network, comprising of Nagaland, Manipur, South Assam, Mizoram, Tripura and Meghalaya, after partial collapse Restoration of 132 kv Network, comprising of Nagaland, Manipur (except Jiribam) and Loktak, after partial collapse Reporting Procedure 64 Annexures : I II List of Power Stations, whether Black Start facility is available List of Sub-Stations, whether synchronizing facilities is available III List of Shunt Reactors in NER 74 Page 3 of 74

4 CHAPTER 1 BLACK START FACILITY 1.1 Existing Black Start Facilities : A list of Generating Stations of NER (North Eastern Region) having black start facilities is elaborated in Annexure-I 1.2 Survival/ Auxiliary Power requirement: Survival/Auxiliary power is required to avoid damages of some equipments as well as functioning of some essential facilities, in case of supply failure. Immediate arrangement of power is very essential for the following:- 1. Battery Charging 2. Emergency Lighting 3. Compressors for breaker operation 4. Lubricating Oil Pumps 5. Communication & Telemetry System 6. Turbine Emergency Oil Pump In power stations of NER, auxiliary power requirement is very nominal i.e. around kw as unit sizes are small except Ranganadi units. 1.3 Start up power requirement: For restoration of Generating Unit, start up power is required for its auxiliaries. The requirement of Start up power of various units is as follow:- Gas - 2 % of Unit Capacity Hydro - 1 % of Unit Capacity Start up power requirement for Gas Generating Unit is high as the major auxiliaries like Gas Compressor, BFP, ID Fan, FD Fan, CW Pump etc. are of bigger size and the starting torque is large. However, start up power requirement for Hydro Generating Unit is less because of few auxiliaries. List of DG Set installed in the Generating Stations is at Annexure-I Page 4 of 74

5 1.4 Synchronizing facilities at Power Stations / major Sub-Stations : Synchronizing facilities play a vital role in building up of systems and also for interconnection of different sub-systems/islands. List of major Sub-Stations which have synchronization facilities is indicated at Annexure-II. 1.5 Shunt Reactors at major Power Station and Sub-Stations: It is very essential to contain voltage during the restoration process of a collapsed system. During the early restoration process, lines are generally lightly loaded due to the restricted drawl by the drawing utilities and voltage starts rising up in different buses as system size grows. Shunt Reactors play a vital role to contain voltage. List of Shunt Reactors available in NER is indicated in Annexure - III. Page 5 of 74

6 CHAPTER 2 SYSTEM RESTORATION APPROACH The following specific points must be adopted considering the importance of system restoration:- 2.1 General Guidelines: i) This document should be available in the Control Room of each Load Despatch Centre & readily accessible to all system operators. ii) Black Start and Restoration Procedure of Regional Grid under various conditions (Partial / Total Blackout) shall be reviewed/updated by NERLDC annually in consultation with NLDC, all Users, STU, SLDC, CTU and NERPC Secretariat. (As per Clause No 5.8.a of IEGC) iii) Black Start and Restoration Procedure of each system of User s/stu/ctu within a Region under various conditions (Partial / Total Blackout) will be finalized by the concerned User s/stu/ctu in co-ordination with NERLDC. The procedure will be reviewed, confirmed and/or revised once every year. Mock trial run of this procedure for different sub-system shall be carried out by User s/stu/ctu at least once in every six months under intimation of NERLDC. Diesel Generators set for black start would be tested on weekly basis and test report shall be sent to NERLDC on quarterly basis. (As per Clause No 5.8.b of IEGC) iv) List of essential loads with categories to be prepared by User/SLDC and sent to NERLDC. Inter State/Inter Regional links, synchronizing points and essential loads to be restored on priority shall be available with NLDC, RLDC & SLDC. (As per Clause No 5.8.c of IEGC) v) NERLDC will co-ordinate entire restoration process through SLDC /ISGS /POWERGRID etc. vi) During restoration process, NERLDC is to be allowed to operate the Grid with reduced security standard for voltage and frequency in order to achieve fastest possible recovery. (As per Clause No 5.8.d of IEGC) vii) All communication channels required for voice communication during the restoration process must be operational. At least one channel of voice communication is to be kept free for NERLDC communication. (As per Clause No 5.8.e of IEGC & As per Clause No 17 of CEA (Grid Standards) Regulation) Page 6 of 74

7 viii) Healthiness of communication system and ancillaries at all Load Despatch Centres, Power Stations and Sub-Stations should be checked at least once in every week to ensure availability of communication system during the periods of crisis. ix) List of PSTN, Mobile & ULDC phone numbers of Control Rooms of all Load Despatch Centres, Power Stations and important Grid Sub-Stations should be available at all Control Rooms and to be distributed to all concerned. Any change or addition of above phone numbers should be incorporated time to time and to be communicated to all concerned. x) Constituents should organize one day appreciation course on power system restoration at regional level, at least once in a year for a. Top Management Group/Chief of Load Despatch Centres b. Load Despatch Personnel/Power System Operators/Sub-Station Operators xi) System Operators are expected to be thoroughly conversant with a. Reactive Capability of Generators b. Voltage Control through the following means :- Charging the shorter line first Switching off Capacitor Bank Taking Bus Reactors into service Charging Transformers and taking Bus Reactors into service Converting Line Reactors into Bus Reactors wherever feasible. Operating Generators at minimum Voltage levels Changing Transformer Taps Energisation of fewer High Voltage Lines. c. Network connectivity by heart and d. They should be able to converse fluently in Hindi/English xii) Power Station which has Black Start capability should be tested at least once in a month. Power Station which has DG Set should be explored for Black Start Capability. xiii) Synchronization facility wherever available should be checked periodically and should be kept in working condition. Periodic report of non-functioning of Synchronoscope is to be sent to NERLDC. xiv) All equipments such as Disturbance Recorders and Event Loggers shall be kept in healthy condition, so that under no condition such important data is lost. Periodic report of non-functioning of Disturbance Recorder/Sequential Event Recorder to be sent to NERLDC. (As per 15.4 of CEA (Grid Standards)Regulation) Page 7 of 74

8 xv) Priority wise loads are to be secured in steps during restoration process. This is to be documented by each User/SLDC and informed to NERLDC. xvi) OLTC of Transformers shall be tested at least once in a week. Periodic report of nonfunctioning of OLTC of Transformer to be sent to NERLDC. 2.2 Initial Course of Action: i) Assess (a) extent of black out, (b) whether any sub-system/island is alive or not, (c) whether interconnection with ER is still there or not. If interconnection with ER is there, then how much load can be connected ii) Appraise the severity of disturbance to all concerned. iii) Open all circuit breakers at Power Station / Sub-Stations that have blacked out, to establish well defined starting point of restoration. iv) Note the relay indications and reset them, if operated. v) Check whether any equipment or any element has suffered damage or developed a technical snag. vi) Chalk out the optimum path for restoration after checking the grid elements that were under outage before disturbance. vii) Defer all planned outage as per IEGC (g) 2.3 Important Considerations during Restoration : i) Generating Stations which have black start facilities have to start up immediately. ii) Availability of Generation Capacity in each island / sub system to be ensured. iii) Availability of transmission lines in the interconnection between islands / sub systems to be ensured. iv) Load to be added in small steps with smaller and radial loads. Larger load may be connected after consultation with NERLDC. v) For developing island / sub system, special care should be taken to closely coordinate the load pick-ups with the ramp rate of generation and to be ensured that the frequency of the island is maintained within sustainable limit (around 50 Hz). vi) If required, Governor and AVR of the units of the island are to be kept in manual mode. Page 8 of 74

9 vii) UFRs are to be kept deactivated as frequency excursions at this stage may be wider than normal condition. SPS are also to be kept deactivated. viii) A reasonable active to reactive power ratio is to be maintained so that the machine can be operated normally. ix) Auxiliary power to be readily available so that machine can be operated normally. x) Total auxiliary power drawn by the sub-system to be kept within 3% of the capacity of the source. xi) Before synchronization between two islands there should be proper co-ordination for frequency adjustment. xii) Risky synchronization shall be avoided as small island may not be able to survive the jerk xiii) While releasing loads, it is to be ascertained whether machines can supply the power. xiv) Tap Position of Transformer, Bus Voltage and Frequency at Power Stations and Sub- Stations should be closely monitored to ensure that over fluxing does not occur. xv) Shift personnel should promptly formulate the strategy to be adopted in co-ordination with NERLDC for quick restoration of the Grid. xvi) The work of restoration in the Control Room should be shared & co-ordinated among the shift personnel for smooth & quick restoration. Crisis Management Group to be formed, consisting of expert personnel & called for early restoration of the system. xvii) Shift personnel should preferably be retained till restoration is over, before handing over the charge to the next shift. 2.4 Special Consideration in extending/availing start up power: I. Power Plant Operators should be able to differentiate between the followings : a. Full auxiliary power needed to start all machines b. Minimum auxiliary power needed to start a minimum number of machines. II. For availing start up power, the following considerations should be kept in mind : a. Nearness to the source b. 132 kv lines vis-à-vis 220 kv/ 400 kv lines c. Shorter route having a number of intermediate sub-stations vis-a-vis longer route having very few/ no intermediate sub-stations III. For extending start up power from one sub-system to another sub-system or from one utility to another utility, the following clear-cut authority should be given to SLDC :- a. Line through which start up power is to be extended Page 9 of 74

10 b. Quantum of such start up power c. Normal time period admissible IV. Concerned SLDC should also be empowered to resort to load shedding or bring up additional generation wherever possible, to extend start up power to neighboring subsystems/utilities during the period of crisis. 2.5 DON TS: i) Do not panic ii) Do not load any Generator beyond 80% of its capacity iii) Do not load any Line/ICT beyond 80% of its capacity iv) Do not hastily connect loads and ensure that the island / sub-system frequency be within sustainable range v) Once power extended to a Power Station/Utility, it should not be withdrawn except in case of extreme emergency and without intimation to NERLDC, as actions taken up at Power Stations would have to be redone. vi) No communication disputes should be raised during the restoration period. vii) Till the restoration procedure is over, load despatch centers should not be disturbed in undesirable manner while discharging their duties and they should not be expected to function as Management Information System. Page 10 of 74

11 CHAPTER 3 Power Map of North Eastern Region Page 11 of 74

12 CHAPTER 4 Page 12 of 74

13 CHAPTER 5 BROAD CLASSIFICATION OF NER GRID: 5.1 North Eastern Region (NER) comprises of seven states viz Arunachal Pradesh, Assam, Manipur, Meghalaya, Mizoram, Nagaland & Tripura. NHPC & NEEPCO are the Central Generating Companies presently operating in the region with installed capacity of 105 MW & 1130 MW respectively. Total installed capacity of the region connected to the NER Grid is 2091 MW. Depending on the network connectivity, NER Grid is broadly classified as follows / 220 kv Network of POWERGRID as backbone of NER Grid / 132 kv Network of Assam System / 132 kv Network of Arunachal Pradesh System kv Network comprising of Nagaland, Manipur, South Assam, Mizoram, Tripura and Meghalaya Page 13 of 74

14 Page 14 of 74

15 / 220 kv Network of POWERGRID as backbone of NER Grid: This is the main back-bone network of NER Grid comprising of 400 kv and 220 kv transmission lines of POWERGRID(PG). NER Grid is connected to ER Grid through this network. The network configuration is described as below: a. 400 kv Bongaigaon (PG) Sub-Station of NER is connected with 400 kv New Siliguri (PG) Sub-Station of ER through 400 kv D/C New Siliguri Bongaigaon lines. b. 220 kv Salakati (PG) Sub-Station of NER is connected to 220 kv Birpara (PG) Sub-Station of ER through 220 kv D/C Birpara Salakati lines. 220 kv Salakati Sub-Station and 400 kv Bongaigaon Sub-Station are connected through 315 MVA ICT. c. Bongaigaon (PG) Sub-Station is connected to Balipara (PG) Sub-Station through 400 kv D/C Bongaigaon Balipara lines. d. 400 kv D/C Balipara Misa lines and 400 kv D/C Balipara Ranganadi lines connect Balipara (PG) Sub-Station with Misa (PG) Sub-Station and Ranganadi (NEEPCO) Power Station respectively. 400 kv Bus of Misa is connected to 220 kv Bus through 315 MVA ICT. e. Misa (PG) Sub-Station is connected with Kopili (NEEPCO) Power Station, Dimapur (PG) Sub-Station and AGBPP (NEEPCO) through 220 kv T/C Misa Kopili lines, 220 kv D/C Misa Dimapur lines and 400 kv S/C Misa Kathalguri line (charged at 220 kv) respectively. f. Misa (PG) Sub-Station is also connected to Mariani (Assam) Sub-Station and Samaguri (Assam) Sub-Station through 220 kv S/C Misa Mariani line and 220 kv D/C Misa Samaguri line. g. Misa (PG) Sub-Station is connected with Killing (Byrnihat) Sub-Station of Meghalaya through 220 kv D/C Misa Killing lines. h. Mariani Sub-Station is connected to AGBPP (NEEPCO) through 400 kv S/C Mariani Kathalguri line (charged at 220 kv) Page 15 of 74

16 Page 16 of 74

17 / 132 kv Network of Assam System: Assam has its own 220 kv & 132 kv Network through which it is connected to the Main Grid. Except South Assam, connectivity of Assam system with the Main Grid is better than other states connectivity to the Main Grid. Connectivity of Assam system with the Grid is as follows:- a. BTPS (Assam) Sub-Station is connected with Salakati (PG) Sub-Station through 220 kv D/C BTPS Salakati lines. Again, 220 kv Bus of BTPS is connected to 132 Bus through 2 X 80MVA + 1 X 160 MVA. b. Dhaligaon, Barnagar, Nalbari, Rangia, Rowta, Sipajhar, Sisugram and Depota Sub-Stations are connected with BTPS, Kahilipara, Pavoi, Samaguri and Balipara (PG) Sub-Stations through 132 kv lines. 220 kv Bus of Samaguri Sub-Station is connected to 132 kv Bus through 3 X 50 MVA ICT. Again, Samaguri Sub-station is connected with Balipara (PG) Sub-station through 220 kv Samaguri Balipara S/C line. c. Agia Sub-Station is connected with BTPS Sub-Station through 220 kv D/C BTPS Agia. Presently, one circuit of 220 kv BTPS Agia is under outage. d. Sarusajai Sub-Station is connected with Agia Sub-Station through Agia Boko- Sarusajai line and Agia Sarusajai respectively. e. Sarusajai Sub-Station is connected with Samaguri Sub-Station and Langpi Power Station through 220 kv D/C Sarusajai Samaguri lines and 220 kv D/C Sarusajai Langpi lines respectively. f. Kahilipara Sub-Station is connected with Sarusajai Sub-Station through four numbers of 132 kv Sarusajai Kahilipara lines & with Rangia Sub-Station through 132 kv Kahilipara Sishugram - Rangia & 132 kv S/C Kahilipara Rangia lines. g. LTPS, NTPS, Tinsukia and Dibrugarh Sub-System is connected with Mariani Sub-Station and AGBPP through 132 kv S/C LTPS - Mariani and 220 kv D/C Tinsukia AGBPP lines respectively. h. Mariani, Golaghat and Bokajan Sub-Stations are connected with Dimapur (PG) Sub-Station through 132 kv S/C Mariani Golaghat - Bokajan - Dimapur line. i. Gohpur, Pavoi (Bishwanath Chariali), North Lakhimpur, Dhemaji and Majuli Sub-Stations are connected with Nirjuli (PG) Sub-Station through 132 kv S/C Nirjuli Gohpur line. Gohpur, Pavoi (Bishwanath Chariali), North Lakhimpur, Dhemaji and Majuli Sub-Stations are also connected with Balipara (PG) Sub- Station through 132 kv Balipara Gohpur line and with Samaguri and Depota Page 17 of 74

18 Sub-Stations through 132 kv Samaguri Depota Pavoi line (T-connection near Depota in between Depota & Pavoi). Page 18 of 74

19 Page 19 of 74

20 / 132 kv Network of Arunachal Pradesh System : The connectivity of 220 kv & 132 kv Network of Arunachal Pradesh is as follow :- a) Ziro(PG), Daporizo and Along Sub-Stations are connected with Ranganadi (NEEPCO) Power Station through 132 kv S/C Ranganadi Ziro line. b) Nirjuli (PG) Sub-Station is connected with Ranganadi (NEEPCO) Power Station & SMS Sub-Station of Arunachal through 132 kv S/C Ranganadi SMS - Nirjuli line (T Connection at SMS) and also with Gohpur Sub-Station of Assam through 132 kv S/C Nirjuli Gohpur line. c) Itanagar Sub-Station is connected with 132 kv Nirjuli (PG) Sub-Station through four nos. 33 kv feeders. Again, Itanagar can draw power from SMS Sub-station via Naharlagun Sub-station through 132 kv SMS Naharlagun-Itanagar line (Presently charged at 33 kv). d) Khupi, Kimi Sub-Stations are connected with Balipara (PG) Sub-Station through 132 kv S/C Balipara Khupi - Kimi line and Deomali is connected with AGBPP (NEEPCO) through 220 kv S/C AGBPP Deomali line respectively. Page 20 of 74

21 Page 21 of 74

22 kv Network comprising of Nagaland, Manipur, South Assam, Mizoram, Tripura and Meghalaya : The connectivity of 132 kv Network comprising of Nagaland, Manipur, South Assam, Mizoram, Tripura and Meghalaya is as follow :- 1. Nagaland System is connected with the Main Grid through :- a. 132 kv D/C Dimapur (PG) Dimapur line. b. 132 kv S/C Dimapur (PG) Kohima line. c. 132 kv S/C Karong (Manipur) Kohima line. d. 132 kv S/C Doyang (NEEPCO) - Mokokchung line. e. 132 kv S/C Mariani (Assam) Mokokchung line. f. 66 kv S/C Dimapur Bokajan (Assam) line ** Nagaland is also connected with Assam system through the following 33 kv and 11 kv feeders : i) Gargaon Naginimara ii) Sonari Tigit iii) Chanki - Moriani 2. Manipur System is connected with the Main Grid through :- a) 132 kv S/C Imphal (PG) Imphal line. b) 132 kv S/C Kohima (Nagaland) Karong line. c) 132 kv S/C Loktak (NHPC) Ningthoukhong line. d) 132 kv S/C Loktak (NHPC) Rengpang line. e) 132/33 kv, 1 X 20 MVA Transformer at Jiribam (PG) Sub-Station 3. Mizoram System is connected with the Main Grid through :- a) 132 kv S/C Aizawl (PG) Zemabawk line. b) 132 kv S/C Aizawl (PG) Longmol line. c) 132 kv S/C Badarpur (PG) Kolasib line. d) 132 kv S/C Aizawl (PG) Kolasib line. 4. Tripura System is connected with the Main Grid through :- a) 132 kv D/C AGTPP (NEEPCO) Agartala lines Page 22 of 74

23 b) 132 kv S/C Kumarghat (PG) P K Bari line c) 132 kv S/C Dullavcherra (Assam) Dharmanagar (Missiontila) line 5. South Assam is connected with the Main Grid through :- a) 132 kv S/C Badarpur(PG) Panchgram line. b) 132 kv S/C Lumshnong (Meghalaya) Panchgram line c) 132 kv S/C Dharmanagar (Tripura) Dullavcherra line. d) 132 kv S/C Jiribam (PG) Pailapool line. e) 132 kv S/C Haflong (PG) Haflong line. f) 33 kv S/C Khandong (NEEPCO) Umrangshu line. 6. Meghalaya system is connected with the Main Grid through :- a) 132 kv S/C Panchgram(Assam) Lumshnong line b) 132 kv D/C Khliehriat(PG) Khliehriat lines c) 132 kv D/C Kahilipara(Assam) - Umtru lines d) 132 kv D/C Sarusajai (Assam) Umtru lines 7. The connectivity of the 132 kv System with 220 kv System & major connectivity of intra 132 kv System :- a. Dimapur (PG) Sub-Station is connected with Misa (PG) Sub-Station through 220 kv D/C Misa Dimapur lines. 220 kv Bus of Dimapur (PG) Sub-Station is connected to 132 kv Bus through 2X100 MVA ICT. b. Dimapur (PG) Sub-Station is connected with Imphal (PG) Sub-Station through 132 kv S/C Dimapur Imphal line. c. Imphal (PG) Sub-Station is connected with Loktak (NHPC) Power Station through 132 kv S/C Imphal Loktak line. d. Loktak (NHPC) Power Station is connected with Jiribam (PG) Sub-Station through 132 kv S/C Loktak Jiribam line. e. Jiribam (PG) Sub-Station is connected with Haflong (PG) Sub-Station, Badarpur (PG) Sub-Station and Aizawl (PG) Sub-Station through 132 kv S/C Jiribam Haflong line, 132 kv S/C Jiribam Badarpur line and 132 kv S/C Jiribam Aizawl line respectively. f. Khandong (NEEPCO) Power Station is connected with Kopili (NEEPCO) Power Station through 132 kv D/C Kopili Khandong lines. 220 kv Bus of Kopili Power Station is connected to 132 kv Bus through 1X160 MVA ICT. Page 23 of 74

24 g. Khandong (NEEPCO) Power Station is connected with Khliehriat (PG) Sub- Station and Haflong (PG) Sub-Station through 132 kv D/C Khandong Khliehriat lines and 132 kv S/C Khandong Haflong line respectively. h. Badarpur (PG) Sub-Station is connected with Khliehriat (PG) Sub-Station, Kumarghat (PG) Sub-Station, Jiribam (PG) Sub-Station and Aizawal (PG) Sub-Station through 132 kv S/C Khliehriat Badarpur line, 132 kv S/C Kumarghat Badarpur line, 132 kv S/C Badarpur Jiribam line and 132 kv S/C Badarpur Kolasib - Aizawl lines respectively. i. Kumarghat (PG) Sub-Station is connected with AGTPP (NEEPCO) and Aizawl (PG) Sub-Station through 132 kv S/C Kumarghat AGTPP line and 132 kv S/C Kumargaht Aizawl line respectively. Page 24 of 74

25 CHAPTER 6 BLACK START & RESTORATION PROCEDURES This Chapter explains broad guidelines for restoring the system after black out. The procedure is split up for the following scenarios:- 1. Restoration of NER Grid after total collapse, when power from Eastern Region (ER) is available 2. Restoration of NER Grid after total collapse, when power from Eastern Region (ER) is not available 3. Restoration of 132 kv Network comprising of Nagaland, Manipur, South Assam, Mizoram, Tripura and Meghalaya, after partial collapse. 4. Restoration of 132 kv Network comprising of Nagaland, Manipur (except Jiribam) and Loktak, after partial collapse. NER Grid under above scenarios will be restored after building up of some sub-systems / islands on the basis of available resources. Source of start up power is to be identified whether it is available within sub-system / island or outside the sub-system / island for early restoration. The following procedure is to be adopted for restoration of affected system:- I. Source of start up power II. Identifying the critical / essential loads of each sub-system / island III. Points of synchronization with other sub-system / island IV. Action to be taken by various Generating Stations and Sub-Stations. Page 25 of 74

26 6.1 Restoration of NER Grid after total collapse, when power from ER is available For restoration of NER Grid from total collapse condition, a multi pronged restoration strategy is envisaged in which some sub-systems/islands are to be built up simultaneously by utilizing power from Eastern Region (ER) and black start facilities available in various Power Stations in North Eastern Region. For restoration of NER Grid from total collapse condition, the following sub-systems / islands are to be built up in parallel: The system, consisting of the following sub-systems are to be built up in parallel, by utilizing power from ER Sub system #1 consisting of Bongaigaon, Salakati, Gelephu, Balipara, Ranganadi, Ziro, Nirjuli, Itanagar, Gohpur, Pavoi, Depota, Rowta, Dhemaji, North Lakhimpur, Majuli, Misa, Samaguri, Mariani, AGBPP, Deomali, Dimapur, Doyang, Nagaland System & Kopili, Khandong, Khliehriat (PG), Haflong, Badarpur, Panchgram and Kolasib. Sub system #2 consisting of BTPS, Agia, Dhaligaon, Barnagar, Nalbari, Rangia, Sipajhar, Sarusajai, Kahilipara and Langpi Island consisting of NTPS, LTPS with Dibrugarh, Nazira and Tinsukia. (ISLAND B) Island consisting of Meghalaya System. (ISLAND C) Island consisting of AGTPP, Tripura, Mizoram and Dullavcherra. (ISLAND D) Island consisting of Loktak, Manipur and Pailapool. (ISLAND E) Page 26 of 74

27 6.1.1 Restoration of systems to be built up by utilizing power from ER Sub-system #1 and sub-system #2 shall to be restored in parallel after taking power from Eastern Region. Simultaneously, all the generating Stations which have black-start facilities are advised to bring their units as fast as possible, so that, islands can be formed for early restoration of the system Restoration of sub-system #1 This sub-system consists of Bongaigaon, Salakati, Gelephu, Balipara, Ranganadi, Ziro, Nirjuli, Itanagar, Gohpur, Pavoi, Depota, Rowta, North Lakhimpur, Dhemaji, Majuli, Misa, Samaguri, Mariani, AGBPP, Deomali, Dimapur, Doyang, Nagaland System & Kopili, Khandong, Khliehriat (PG), Haflong, Badarpur, Panchgram and Kolasib. Restoration procedure of this sub-system is as follow:- 1) Power required for this sub system shall be taken from New Siliguri (ER) Sub-Station to Bongaigaon (NER) Sub-Station through any one of 400 kv D/C New Siliguri Bongaigaon lines. 2) In case of delay in receiving power from New Siliguri (ER) Sub-Station, then the following procedure shall be adopted :- Salakati (NER) Sub-Station shall receive power from Birpara (ER) Sub- Station through any one of 220 kv D/C Birpara Salakati lines. Any one of 400 kv Bus(s) at Bongaigaon Sub-Station shall be charged through 315 MVA ICT at Bongaigaon Sub-Station. Again, Salakati Sub-Station shall charge any one of 220 / 132 kv, 50 MVA ICT & shall extend power to Gelephu through 132 kv S/C Saklakati Gelephu line.load at Gelephu can be connected in co-ordination with NLDC & Bhutan. Bus Reactors (at Annex III) at New Siliguri Sub-Station and Bongaigaon Sub-Station shall be taken into service to contain voltage. Bongaigaon (PG) Sub-Station shall extend power to Balipara (PG) Sub-Station through any one of 400 kv D/C Balipara Bongaigaon lines. Any one of 220 kv Bus(s) at Salakati Sub-Station shall be charged through 315 MVA ICT at Bongaigaon Sub-Station. If required, Tertiary Reactor at Bongaigaon (at Annex III) may be taken into service to contain voltage. 3) Balipara (PG) Sub-Station shall extend power to Misa (PG) Sub-Station through any one of 400 kv D/C Balipara Misa lines and Shunt Reactors (at Annex III) at Balipara and Misa Sub-Stations shall be taken into service Page 27 of 74

28 to contain voltage. Any one of 220 kv Bus(s) at Balipara Sub-Station shall be charged through 315 MVA ICT at Balipara Sub-Station. If required, Tertiary Reactor at Balipara (at Annex III) may be taken into service to contain voltage. 132 kv Bus at Balipara Sub-Station shall be charged through 2X50 MVA ICT at Balipara Sub-Station. Balipara Sub-Station shall extend power to Khupi & Kimi Sub-Stations through 132 kv Balipara Khupi - Kimi lines. Load at Khupi & Kimi shall be connected in coordination with SLDC, Arunachal Pradesh. 4) Ranganadi (NEEPCO) Power Station can receive power from Balipara (PG) Sub-Station through any one of 400 kv D/C Balipara Ranganadi lines. Any one of 132 kv Bus(s) at Ranganadi Power Station shall be charged through any one of 2X360 MVA ICT at Ranganadi Power Station. Ranganadi (NEEPCO) Power Station shall extend power to SMS (Arunachal Pradesh) and Nirjuli (PG) Sub-Stations through 132 kv S/C Ranganadi SMS - Nirjuli (T Connection at SMS) and shall extend power to Daporijo and Along (Arunachal Pradesh) Sub-Stations through 132 kv S/C Ranganadi Ziro - Daporijo Along lines. Shunt Reactors (at Annex III) at Ranganadi Power Station shall be taken into service to contain voltage. Load shall be connected at SMS, Ziro, Daporijo and Along in coordination with SLDC, Arunachal Pradesh. 5) 33 kv Bus at Nirjuli Sub-Station shall be charged through any one of 1X10+1X16 MVA ICT at Nirjuli Sub-Station. Nirjuli Sub-Station shall extend power to Itanagar (Arunachal Pradesh) Sub-Station through any one of four nos of 33 kv feeders. Itanagar Sub-Station can also receive power from SMS Sub-Station through Naharlagun (Arunachal Pradesh) Sub- Station. Load shall be connected at Itanagar in co-ordination with SLDC, Arunachal Pradesh. 6) Balipara (PG) Sub-Station shall also extend power to Gohpur (Assam) Sub- Station through 132 kv S/C Balipara Gohpur line. Gohpur Sub-Station can also receive power from Samaguri and Depota Sub-Stations through 132 kv Samaguri Pavoi (Bishwanath Chariali) - Gohpur line and 132 kv Depota Pavoi (Bishwanath Chariali) Gohpur line respectively. Load shall be connected at Gohpur in co-ordination with SLDC, Assam. Balipara (PG) Sub-Station shall extend power to Depota Sub-Station through 132 kv Balipara Depota line. Load at Depota shall be connected in co-ordination Page 28 of 74

29 with SLDC, Assam. Depota Sub-Station shall extend power to Rowta Sub- Station through 132 kv Depota Rowta line. Load at Rowta shall be connected in co-ordination with SLDC, Assam. 7) Gohpur (Assam) Sub-Station shall extend power to North Lakhimpur, Dhemaji and Majuli Sub-Stations. Loads at North Lakhimpur, Dhemaji and Majuli shall be connected in co-ordination with SLDC, Assam. 8) Ranganadi (NEEPCO) Power Station shall bring their machines if required and synchronize with this sub-system. Otherwise, if the power received from Balipara Sub-Station is delayed, Ranganadi Power Station shall black start one of their three units and shall charge 132 kv Bus and extend power to SMS, Nirjuli & Ziro Sub-Stations and wait for extension of power from Balipara Sub-Stations. If possible they can also charge one circuit of 400 kv D/C Ranganadi Balipara line for synchronization. 9) Gohpur Sub-Station can also receive power from Nirjuli (PG) Sub-Station through 132 kv Nirjuli Gohpur line. Note : SLDC, Assam and Arunachal Pradesh shall co-ordinate with NERLDC before connecting loads to their systems. 10) Any one of 220 kv Bus(s) at Misa Sub-Station shall also be charged through 315 MVA ICT at Misa Sub-Station after receiving power from Balipara (PG) Sub-Station. If required, Tertiary Reactor at Misa (at Annex III) may be taken into service to contain voltage. 11) Misa Sub-Station shall extend power to Samaguri (Assam) Sub-Station through any one of 220 kv D/C Misa Samaguri lines. Shunt Reactors (at Annex III) at Samaguri Sub-Station shall be taken into service to contain voltage. 132 kv Bus at Samaguri Sub-Station may be charged through any one of 3X50 MVA ICT. Load at Samaguri shall be connected in coordination with SLDC, Assam. 12) Misa Sub-Station shall extend power to Byrnihat (Meghalaya) Sub-Station through any one of 220 kv D/C Misa Killing (Byrnihat) lines. 132 kv Bus at Byrnihat Sub-Station shall be charged through any one of 2X160 MVA ICT. Byrnihat Sub-Station shall extend power to EPIP II Sub-Station through any one of 132 kv D/C Byrnihat EPIP II lines. Load at EPIP II shall be connected in co-ordination with SLDC, Meghalaya. EPIP II Sub- Page 29 of 74

30 Station shall extend power to EPIP I Sub-Station through any one of 132 kv D/C EPIP II EPIP I lines. Load at EPIP I shall be connected in coordination with SLDC, Meghalaya. 13) Mariani (Assam) Sub-Station can receive power either from Misa Sub- Station through 400 kv S/C Misa Mariani line (Charged at 220 kv) or Samaguri (Assam) Sub-Station through 220 kv S/C Samaguri Mariani line (presently one circuit is available). Shunt Reactors (at Annex III) at Mariani Sub-Station shall be taken into service to contain voltage. Load at Mariani shall be connected in co-ordination with SLDC, Assam. 14) Kopili (NEEPCO) Power Station shall receive power from Misa Sub- Station through any one of 220 kv T/C Misa Kopili lines. Kopili Power Station shall bring their machines by taking start up power from this subsystem and synchronize the machines with this sub-system. Otherwise, if the power received from Misa Sub-Station is delayed, Kopili Power Station shall black start one of four units and shall charge 220 kv Bus and extend power to Khandong Power Station and wait for extension of power from Misa Sub-Stations. 15) 132 kv Bus at Kopili Power Station shall be charged through 160 MVA ICT at Kopili Power Station. 16) Kopili Power Station shall extend power to Khandong (NEEPCO) Power Station through any one of 132 kv D/C Kopili Khandong lines. Khandong Power Station shall bring machines, if required, by taking start up power from this sub-system and synchronize the machines with this sub-system. Otherwise, if the power received from Kopili Power Station is delayed, Khnadong Power Station shall black start one of three units and shall charge 132 kv Bus and extend power to Haflong & Khliehriat Sub-Stations and wait for extension of power from Kopili Power Station. If possible, they can also charge one circuit of 132 kv D/C Kopili Khandong lines for synchronization. 17) Khandong Power Station shall charge 33 kv Bus through any one of 1X16+1X7.5 MVA Transformer. Khandong shall extend power to Umrangshoo Sub-Station through 33 kv S/C of Khandong Umrangshoo line. Load at Umrangsho shall be connected in co-ordination with SLDC, Assam. Page 30 of 74

31 18) Khandong Power Station shall extend power to Khliehriat (PG) and Haflong (PG) Sub-Stations through any one of 132 kv D/C of Khandong Khliehriat lines and 132 kv S/C Khandong Haflong line respectively. 19) Khliehriat (PG) Power Station shall extend power to Badarpur (PG) Sub- Station through 132 kv S/C Khliehriat- Badarpur line. 20) Badarpur Sub-Station shall extend power to Panchgram (Assam) Sub- Station through 132 kv S/C Badarpur Panchgram line. Panchgram Sub- Station shall extend power to Sreekona Sub-Station through 132 kv Panchgram Sreekona line. Load at Panchgram and Sreekona shall be connected in co-ordination with SLDC, Assam. 21) This sub-system shall be synchronized with Island D at Badarpur (PG) through 132 kv S/C Badapur Kumarghat line. This sub-system shall be also synchronized with Island D at Badarpur (PG) through 132 kv Dullavcherra Panchgram Badarpur line. 22) This sub-system shall be synchronized with Island E at Badarpur (PG) through 132 kv S/C Badapur Jiribam line. 23) This sub-system shall be synchronized with Island C at Khliehriat (PG) through 132 kv D/C Khliehriat Khliehriat lines. 24) Badarpur Sub-Station shall extend power to Kolasib (Mizoram) Sub-Station through 132 kv S/C Badarpur Kolasib line. Load at Kolasib shall be connected in co-ordination with SLDC, Mizoram. 25) Kolasib Sub-Station shall extend power to Bairabi (Mizoram) Power Station for survival/auxiliary power through 66 kv Kolasib Bairabi line. 26) Haflong (PG) Sub-Station shall extend power to Haflong (Assam) Sub- Station through 132 kv S/C Haflong Haflong line. Load at Haflong shall be connected in co-ordination with SLDC, Assam. 27) Mariani Sub-Station shall extend power to AGBPP (NEEPCO) through 400 kv S/C Mariani AGBPP line (charged at 220 kv). AGBPP shall bring their machines by taking start up power from this sub-system and synchronize the machines with this sub-system. AGBPP shall extend power to Deomali (Arunachal Pradesh) Sub-station through 220 kv S/C AGBPP Deomali line. Load at Deomali shall be connected in co-ordination with SLDC, Arunachal Pradesh. 28) Misa (PG) Sub-Station shall extend power to Dimapur (PG) Sub-station through any one of 220 kv D/C Misa Dimapur lines. 132 kv Bus at Page 31 of 74

32 Dimapur Sub-Station shall be charged through any one of 2X100 MVA ICT at Dimapur. 29) Dimapur (PG) Sub-Station shall extend power to Dimapur (Nagaland) Sub- Station through any one of 132 kv D/C Dimapur Dimapur line. Load at Dimapur shall be connected in co-ordination with SLDC, Nagaland. 30) Dimapur (PG) Sub-station shall extend power to Kohima Sub-Station through 132 kv S/C Dimapur Kohima line. Load at Kohima shall be connected in co-ordination with SLDC, Nagaland. 31) Kohima Sub-station shall extend power to Meluri Sub-Station through 132 kv S/C Kohima Meluri line. Load at Meluri shall be connected in coordination with SLDC, Nagaland. 32) Meluri Sub-Station shall extend power to Khiphire Sub-Station through 132 kv S/C Meluri Khiphire line. Load at Khiphire shall be connected in coordination with SLDC, Nagaland. 33) 66 kv Bus at Khiphire Sub-Station shall be charged through any one of 3X6.5 MVA ICT at Khiphire Sub-Station. 34) Khiphire Sub-Station shall extend power to Likhimro Power Station through 66 kv Khiphire Likhimro line. 35) Dimapur (PG) Sub-Station shall also extend power to Doyang (NEEPCO) Power Station through any one of 132 kv D/C Dimapur Doyang lines. Doyang Power Station shall bring generation, if required and synchronize. Otherwise, if the power received from Dimapur Sub-Station is delayed, Doyang Power Station shall black start one of three units & shall charge 132 kv bus and extend power to Mokakchung Sub-Station. 36) Doyang (NEEPCO) Power Station shall extend power to Mokokchung Sub- Station through 132 kv S/C Doyang Mokukchung line. Load at Mokokchung shall be connected in co-ordination with SLDC, Nagaland. 37) This sub-system may also be synchronized with Island E at Dimapur (PG) through 132 kv S/C Dimapur Imphal line. 38) Dimapur (PG) Sub-Station can also receive power form Mariani Sub- Station through 132 kv S/C Mariani Golaghat Bokajan - Dimapur line. 39) Mokokchung Sub-Station can also receive power from Mariani Sub-Station through 132 kv S/C Mariani Mokokchung line. Presently 132 kv S/C Mariani Mokokchung line is under long outage. Early restoration of this line will help to extend power to Mokokchung. Page 32 of 74

33 Note : SLDC, Assam and Nagaland shall co-ordinate with NERLDC before connecting loads to their system NOTE: If ER power received by Misa Sub-Station is delayed then power shall be taken from the following sources:- i. From Island C, Khliehriat (PG) Sub-Station can receive power from Khliehriat (Meghalaya) Sub-Station through any one of 132 kv D/C Khliehriat Khliehriat lines. ii. From Island C, Panchgram (Assam) Sub-Station can receive power from Khliehriat (Meghalaya) Sub-Station through 132 kv S/C Khliehriat Lumnsnong - Panchgram line. iii. From Island D, Badarpur (PG) Sub-Station can receive power from Kumarghat Sub-Station through 132 kv S/C Badarpur Kumarghat line. iv. From Island D, Kolasib Sub-Station can receive power from Aizawl Sub- Station through 132 kv S/C Kolasib Aizawl line v. From Island D, Panchgram (Assam) Sub-Station can receive power from Dharmanagar Sub-Station through 132 kv S/C Dharmanagar - Dullavcherra - Panchgram line. vi. From Island E, Haflong (PG) Sub-Station can receive power from Jiribam Sub-Station through 132 kv S/C Haflong Jiribam line. vii. From Island E, Dimapur (PG) Sub-Station can receive power from Imphal(PG) Sub-Station through 132 kv S/C Imphal - Dimapur line. Page 33 of 74

34 Sub-system#1 Page 34 of 74

35 Restoration of sub-system #2 This sub-system consists of BTPS, Agia, Dhaligaon, Barnagar, Nalbari, Rangia, Sipajhar, Sarusajai, Kahilipara and Langpi. Restoration procedure for this sub-system is as follow :- 1) From sub-system #1, Salakati (PG) Sub-Station shall extend power to BTPS (Assam) Sub-Station through any one of 220 kv D/C Salakati BTPS lines. 2) BTPS Sub-Station shall extend power to Agia (Assam) Sub-Station through 220 kv BTPS Agia line. Presently one circuit of 220 kv BTPS Agia is available. Load at Agia shall be connected in co-ordination with SLDC, Assam. 3) 132 kv Bus at BTPS Sub-Station shall be charged through any one of 2X80+1X160 MVA ICT at BTPS Sub-Station. BTPS Sub-Station shall extend power to Dhaligaon (Assam) Sub-Station through any one of 132 kv D/C BTPS Dhaligaon lines. Load at Dhaligaon shall be connected in coordination with SLDC, Assam. 4) Dhaligaon Sub-Station shall extend power to Rangia (Assam) Sub-Station and Barnagar (Assam) Sub-Station through 132 kv Dhaligaon Barnagar and 132 kv Dhaligaon Nalbari - Rangia lines. Load at Nalbari, Rangia and Barnagar shall be connected in co-ordination with SLDC, Assam. 132 kv S/C Rangia Barnagar line shall be closed. 5) Again, Rangia shall extend power to Motonga (Bhutan) through 132 kv Rangia Motonga line. Gelephu can also receive power through Motonga. 6) Rangia Sub-Station shall extend power Sisugram (Assam) Sub-Station through 132 kv S/C Rangia Sishugram line. Load at Sishugram shall be connected. If required, Rangia Sub-Station shall extend power to Rowta Sub-Station too through 132 kv Rangia Sipajhar - Rowta & 132 kv Rangia Rowta line. Load at Sipajhar & Rowta may be connected in coordination with SLDC, Assam. 7) Agia (Assam) Sub-Station shall extend power to Sarusajai (Assam) Sub- Station through 220 kv S/C Agia Sarusajai or 220 kv Agia Boko Sarusajai lines. 132 kv Bus at Sarusajai Sub-Station shall be charged through any one of 3X100 MVA ICT at Sarusajai. Load at Sarusajai & Boko shall be connected in co-ordination with SLDC, Assam. Page 35 of 74

36 8) Sarusajai Sub-Station shall extend power to Kahilipara (Assam) Sub-Station through any one line of four nos. of 132 kv Sarusajai Kahilipara lines. Load at Kahilipara shall be connected in co-ordination with SLDC, Assam. 9) Sarusajai Sub-Station shall extend power to Langpi (Assam) Power Station through any one of 220 kv D/C Sarusajai Langpi lines. 10) Kahilipara Sub-Station can also receive power from Rangia and Sisugram Sub-Stations through 132 kv S/C Rangia Kahilipara line and 132 kv S/C Sisugram Kahilipara line respectively. 11) Sarusajai Sub-Station can also receive power from Samaguri Sub-Station of sub-system #1 through any one of 220 kv D/C Sarusajai Samaguri lines. Remark : SLDC, Assam shall co-ordinate with NERLDC before connecting loads. Note : If ER power received by this system is delayed then power shall be taken from the following sources :- i. From Island C, Sarusajai Sub-Station can receive power from Umtru (Meghalaya) Power Station through any one of 132 kv D/C Umtru - Sarusajai lines. ii. From Island C, Kahilipara Sub-Station can receive power from Umtru (Meghalaya) Power Station through any one 132 kv D/C Umtru - Kahilipara lines. Page 36 of 74

37 Sub-system #2 Page 37 of 74

38 6.1.2 Restoration of Island B This Island consists of NTPS, LTPS with Dibrugarh, Nazira and Tinsukia. Restoration procedure of this Island by its own black-start facility is as follow 1) NTPS (Assam) shall black-start and charge 66 kv Bus at NTPS. Load at NTPS shall be connected in co-ordination with SLDC Assam. NTPS shall bring and synchronize other units. 2) NTPS shall extend power to LTPS (Assam) through any one of 132 kv D/C LTPS NTPS lines. LTPS shall bring generation and synchronize. 3) NTPS shall extend power to Tinsukia & Nazira (Assam) Sub-Stations through any one of 66 kv D/C NTPS Tinsukia and any one of 66 kv D/C NTPS Nazira lines respectively. Load at Tinsukia and Nazira shall be connected in coordination with SLDC Assam. 4) 132 kv Bus at NTPS shall be charged through any one of 2X25 MVA ICT at NTPS. 5) NTPS shall also extend power to Tinsukia (Assam) Sub-Station through 132 kv S/C NTPS -Tinsukia line. 6) LTPS shall extend power to Dibrugarh (Assam) Sub-Stations through 132 kv S/C LTPS Dibrugrah and 132 kv S/C LTPS - Nazira line. Load at Dibrugarh shall be connected in co-ordination with SLDC Assam. 132 kv LTPS Nazira line shall be closed. 7) This island shall be synchronized with sub-system #1 at Mariani (Assam) through 132 kv S/C LTPS Mariani line. Note: If Black start by NTPS is not possible, then start up power for this Island shall be received from the following sources:- i. From sub system #1, Tinsukia Sub-Station can receive power from AGBPP through any one of 220 kv D/C Tinsukia AGBPP line and shall extend start up power to NTPS through 132 kv S/C Tinsukia NTPS line. ii. From sub system #1, LTPS can receive power from Mariani Sub-Station through 132 kv S/C Mariani LTPS line. Note : LTPS shall explore their black start facility Page 38 of 74

39 ISLAND B Page 39 of 74

40 6.1.3 Restoration of Island C This Island consists of Meghalaya System. Meghalaya system can be built up by its own black-start facilities. Restoration procedure for this Island is as follow :- 1) Umiam St I Power Station shall black-start and charge 132 kv Bus at Umiam St I Power Station. Umiam St III Power Station shall also black start and charge132 kv Bus at Umiam St III Power Station. 2) Umiam St I Power Station shall synchronize with Umiam St III Power Station at Umium St III Power Station through any one of 132 kv D/C Umiam St I Umiam St III lines. Umiam St I & III Power Stations shall bring and synchronize other machines. Load at Umiam St III shall be connected in coordination with SLDC Meghalaya. 3) Umiam St I Power Station shall extend power to Umiam St II Power Station through 132 kv S/C Umiam St I Umiam II line for survival/auxiliary power. Umiam St II Power Station shall bring generation if required and synchronize. 4) Umiam St III Power Station shall extend power to Umiam St IV Power Station through any one of 132 kv D/C Umiam St III Umiam IV line for survival/auxiliary power. Umiam St IV Power Station shall bring generation if required and synchronize. 5) Umiam St III Power Station shall extend power to Umtru Power Station through any one of 132 kv D/C Umiam St III Umtru lines. Load at Umtru shall be connected in co-ordination with SLDC Meghalaya. Umtru Power Station shall bring generation if required and synchronize. 6) Umiam St I Power Station shall extend power to Mawlai and NEHU Sub- Stations through 132 kv S/C Umiam St I Mawlai line and 132 kv S/C Umiam St I Umiam - NEHU line respectively. Load at Mawlai, Umiam and NEHU shall be connected in co-ordination with SLDC Meghalaya. 7) NEHU Sub-Station shall extend power to Khliehriat Sub-Station through 132 kv S/C NEHU NEIGRIHMS - Khliehriat line or 132 kv NEHU Khliehriat line. Load at Khliehriat and NEIGRIHMS shall be connected in co-ordination with SLDC Meghalaya. 8) Khliehriat Sub-Station shall extend power to Lumsnong Sub-Station through 132 kv S/C Khliehriat- Lumsnong line.load at Lumsnong shall be connected in co-ordination with SLDC Meghalaya. Page 40 of 74

41 9) Again, Power shall be extended to Leshka power station from Khliehriat (Meghalaya) Sub-Station through 132 kv D/C Khliehriat Leshka lines. 10) This island shall be synchronized with sub-system #2 at Sarusajai (Assam) Sub-Station and Kahilipara (Assam) Sub-Station through any one of 132 kv D/C Umtru Sarusajai lines or through any one of 132 kv D/C Umtru Kahilipara lines. 11) This island shall be synchronized with sub-system #1 at Khliehriat (PG) Sub- Station through any one of 132 kv D/C Khliehriat Khliehriat lines. Note: If Black Start by Meghalaya Power Stations is not possible then start up power for this Island shall be received from the following sources :- i. From sub-system#1, Khliehriat (Meghalaya) Sub-Station can receive power from Khliehriat (PG) Sub-Station through any one of 132 kv D/C Khliehriat Khliehriat lines and extend power to Umiam St I and Leshka Power Station through NEHU & Umiam Sub-Stations and 132 kv D/C Khliehriat Leshka lines respectively, for brining generation. ii. From Sub System #1, Khliehriat (Meghalaya) Sub-Station can receive power from Panchgram (Assam) Sub-Station through 132 kv Panchgram - Lumsnong Khliehriat line. iii. From Sub System #2, Umtru (Meghalaya) Sub-System can receive power from Sarusajai (Assam) Sub-Station through any one of 132 kv D/C Sarusajai Umtru lines and extend power to Umiam St III Power Station through any one of 132 kv D/C Umiam St III - Umtru for brining generation. iv. From Sub System #2, Umtru (Meghalaya) Sub-Station can receive power from Kahilipara (Assam) Sub-Station through any one of 132 kv D/C Kahilipara Umtru lines and extend power to Umiam St III Power Station through any one of 132 kv D/C Umiam St III - Umtru for brining generation. v. From Sub System #1, Umtru (Meghalaya) Sub-Station can receive power from Killing (Meghalaya) Sub-Station through 132 kv D/C Killing EPIPII Umtru Page 41 of 74

42 ISLAND C Page 42 of 74

43 6.1.4 Restoration of Island D : This Island consists of AGTPP, Tripura, Mizoram and Dullavcherra. AGTPP and Tripura System can restore its system by their own black start facilities. Restoration procedure for this Island is as follow :- 1) Rokhia (Tripura) Power Station shall black start and charge 66 kv Bus at Rokhia Power Station. Load at Rokhia shall be connected in co-ordination with SLDC, Tripura. Rokhia Power Station shall bring and synchronize other machines. 2) 132 kv Bus at Rokhia Power Station shall be charged through 30 MVA ICT at Rokhia Power Station. 3) Rokhia Power Station shall extend power to Agartala Sub-Station through any one of 132 kv D/C Rokhia Agartala lines. Load at Agartala shall be connected in co-ordination with SLDC, Tripura. 4) AGTPP (NEEPCO) shall black start one of its unit and charge 132 kv Bus at AGTPP. AGTPP shall synchronize Tripura System through any one of 132 kv D/C AGTPP Agartala lines. AGTPP shall bring and synchronize other machines. 5) Agartala Sub-Station shall extend power to Baramura Power Station through 132 kv S/C Agartala Budhjangnagar Jirania - Baramura lines. Baramura Power Station shall bring generation and synchronize with this Island. 6) Rokhia Power Station shall extend power to Udaipur Sub-Station through 132 kv S/C Rokhia Udaipur line. 7) 66 kv Bus at Udaipur Sub-Station shall be charged through 15 MVA ICT at Udaipur Sub-Station. Load at Udaipur shall be connected in co-ordination with SLDC, Tripura. 8) Udaipur Sub-Station shall extend power to Gumti Power Station through 66 kv S/C Udaipur Gumti line. 9) Gumti Power Station shall bring generation if required and synchronize with this Island. 10) Agartala Sub-Station shall extend power to Dhalabil Sub-Station through 132 kv S/C Agartala Dhalabil line. Load at Dhalabil shall be connected in coordination with SLDC, Tripura. Page 43 of 74