Restoration Procedure of NER 2011 - Welcome to NERLDC · 7 Reporting Procedure 63 ... Compressor, BFP, ID Fan, FD Fan, CW Pump etc. are of bigger size and the starting torque is large

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BLACK START AND

RESTORATION PROCEDURES OF

NER GRID

6th REVISION

Released Month : Feb 2011

Prepared by : System Operation Deptt. POWER SYSTEM OPERATION CORPORATION LTD

(A wholly owned subsidiary of POWERGRID) NORTH EASTERN REGIONAL LOAD DESPATCH CENTRE

SHILLONG

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BLACK START AND RESTORATION PROCEDURES OF NER GRID

Doc. Code: NERLDC/SO/MANUAL

Checked by:

Verifed by Reviewed by Approved by:

Prepared and Issued by:

B Medhi Sr Engineer (SO), NERLDC

A Mallick Chief Manager (SO), NERLDC

N R Paul DGM (SO), NERLDC

T S Singh AGM, NERLDC

A Mallick Chief Manager (SO), NERLDC

CLASSIFICATION : OPEN

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CONTENTS

Sl No

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

24

Restoration of NER Grid after total collapse, when power from ER is available

25

Restoration of NER Grid after total collapse, when power from ER is not available

49

Restoration of 132 kV Network, comprising of Nagaland, Manipur, South Assam, Mizoram, Tripura and Meghalaya, after partial collapse

59

Restoration of 132 kV Network, comprising of Nagaland, Manipur (except Jiribam) and Loktak, after partial collapse

61

7 Reporting Procedure

63

Annexures :

I List of Power Stations, whether Black Start facility is available

67

II List of Sub-Stations, whether synchronizing facilities is available

71

III List of Shunt Reactors in NER

73

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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 damage some of the 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 100-150

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

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1.4 Synchronizing facilities at Power Stations / major Sub-Stations :

Synchronizing facilities play a vital role in building up of systems and also for inter-

connection 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 :

Containing over voltage during the restoration process is very much essential. 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 vital role to contain over voltage. List of Shunt Reactors available in NER is

indicated in Annexure - III.

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CHAPTER 2

SYSTEM RESTORATION APPROACH

The following specific points must be given due importance for system restoration:-

2.1 General Guideline: i) This document should be available to 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 NERRPC 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 Generator

sets 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 and essential loads to be restored on

priority. (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 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)

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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 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 in working condition. Periodic report of nonfunctioning of

Synchronoscope to be sent to NERLDC.

xiv) All equipment 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 nonfunctioning of Disturbance Recorder/Sequential Event Recorder to

be sent to NERLDC. (As per 15.4 of CEA (Grid Standards)Regulation)

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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 should be tested at least once in a week. Periodic report

of nonfunctioning of OLTC of Transformer to be sent to NERLDC.

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 5.7.4 (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 line 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 consulting with NERLDC.

v) For developing island / sub system, special care should be taken to closely co-

ordinate 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.

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vii) UFRs to be kept deactivated as frequency excursions at this stage may be wider

than normal condition. SPS 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 should 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 & coordinated

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 change 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

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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

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 sub-systems/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.

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Power Map of North Eastern Region

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CHPATER 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 2056 MW.

Depending on the network connectivity, NER Grid is broadly classified as follows.

1. 400 / 220 kV Network of POWERGRID as backbone of NER

Grid

2. 220 / 132 kV Network of Assam System

3. 220 / 132 kV Network of Arunachal Pradesh System

4. 132 kV Network comprising of Nagaland, Manipur, South

Assam, Mizoram, Tripura and Meghalaya

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5.1.1 400 / 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. Mariani Sub-Station is connected to AGBPP (NEEPCO) through 400 kV S/C

Mariani – Kathalguri line (charged at 220 kV)

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5.1.2 220 / 132 kV Network of Assam System: Assam has its own 220 kV & 132 kV Network through which it is connected to the

Grid. Except South Assam, connectivity of Assam system with the Grid is better than

other states’ connectivity to the 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.

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 with 132 kV Bus through three numbers of 50 MVA

ICT.

c. Sarusajai Sub-Station is connected with BTPS Sub-Station through 220 kV

BTPS - Agia –Boko- Sarusajai line. Presently, one circuit of 220 kV BTPS –

Agia is under outage.

d. Sarusajai Sub-Station is connected with Samaguri Sub-Station through 220 kV

D/C Sarusajai – Samaguri lines and with Langpi Power Station through 220 kV

D/C Sarusajai – Langpi lines.

e. 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 line.

f. 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 S/C

Tinsukia – AGBPP lines respectively.

g. Mariani, Golaghat and Bokajan Sub-Stations are connected with Dimapur (PG)

Sub-Station through 132 kV S/C Mariani – Golaghat - Bokajan - Dimapur line.

h. 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

Sub-Stations through 132 kV Samaguri – Pavoi – Depota line (T connection at

Pavoi).

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5.1.3 220 / 132 kV Network of Arunachal Pradesh System :

The connectivity of 132 kV & 33 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 through four 33 kV feeders from Nirjuli (PG)

Sub-Station.

d) Khupi, Kimi and Deomali Sub-Stations are connected with Balipara (PG) Sub-

Station and AGBPP (NEEPCO) with 132 kV S/C Balipara – Khupi - Kimi line &

220 kV S/C AGBPP – Deomali line respectively.

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5.1.4 132 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 Grid through :-

a. 132 kV S/C Dimapur (PG) – Dimapur line.

b. 132 kV S/C Karong (Manipur) – Kohima line.

c. 132 kV S/C Doyang (NEEPCO) - Mokokchung line.

d. 132 kV S/C Mariani (Assam) – Mokokchung line.

e. 66 kV S/C Dimapur – Bokajan (Assam) line

2. Manipur System is connected with the 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, 6.3 MVA Transformer at Jiribam (PG) Sub-Station & 33 kV

Jiribam (PG) – Jiribam line.

3. Mizoram System is connected with the 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 through :-

a) 132 kV D/C AGTPP (NEEPCO) – Agartala lines

b) 132 kV S/C Kumarghat (PG) – P K Bari line

c) 132 kV S/C Dullavcherra (Assam) – Dharmanagar line

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5. South Assam is connected with the 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 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 two nos. 100 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 line. 220 kV Bus of

Kopili Power Station is connected to 132 kV Bus through 160 MVA ICT.

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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 – Aizawlline respectively.

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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 ER is available

2. Restoration of NER Grid after total collapse, when power from 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.

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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:-

6.1.1 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, 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 Salakati, Gelephu, BTPS, Agia, Dhaligaon, Barnagar,

Nalbari, Rangia, Sipajhar, Sarusajai, Kahilipara and Langpi

6.1.2 Island consisting of NTPS, LTPS with Dibrugarh, Nazira and Tinsukia

6.1.3 Island consisting of Meghalaya System 6.1.4 Island consisting of AGTPP, Tripura, Mizoram and

Dullavcherra. 6.1.5 Island consisting of Loktak, Manipur and Pailapool

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6.1.1 Restoration of systems to be built up by utilizing power from ER Sub-system #1 and sub-system #2 should to be restored in parallel after taking

power from Eastern Region.

6.1.1.1 Restoration of sub-system #1 This sub-system consists of Bongaigaon, 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) If power received from New Siliguri (ER) Sub-Station delayed, 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.

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

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

Page 27 of 73

extend power to Khupi & Kimi Sub-Stations through 132 kV Balipara –

Khupi - Kimi lines. Load at Khupi & Kimi shall be connected in co-

ordination 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 co-


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

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.

Page 28 of 73

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 co-

ordination with SLDC, Assam.

12) Misa Sub-Station shall extend power to Byrnihat (Meghalaya) Sub-Station

through any one of 220 kV D/C Misa – 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-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 co-ordination

with SLDC, Meghalaya.

Page 29 of 73

13) 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.

14) 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.

15) 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 sub-

system 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.

16) 132 kV Bus at Kopili Power Station shall be charged through 160 MVA

ICT at Kopili Power Station.

17) 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 – Misa lines for

synchronization.

18) 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 73

19) 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.

20) Khliehriat (PG) Power Station shall extend power to Badarpur (PG) Sub-

Station through 132 kV S/C Khliehriat- Badarpur line.

21) 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


22) This sub-system shall be synchronized with Island D at Badarpur (PG)

through 132 kV S/C Badapur – Kumarghat line.

23) This sub-system shall be synchronized with Island E at Badarpur (PG)

through 132 kV S/C Badapur – Jiribam line.

24) This sub-system shall be synchronized with Island C at Khliehriat (PG)

through 132 kV D/C Khliehriat – Khliehriat lines.

25) 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.

26) Kolasib Sub-Station shall extend power to Bairabi (Mizoram) Power

Station for survival/auxiliary power through 66 kV Kolasib – Bairabi line.

27) 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.

28) 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.

29) 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

Dimapur Sub-Station shall be charged through any one of 2X100 MVA ICT

at Dimapur.

Page 31 of 73

30) Dimapur (PG) Sub-Station shall extend power to Dimapur (Nagaland) Sub-

Station through 132 kV S/C Dimapur – Dimapur line. Load at Dimapur shall

be connected in co-ordination with SLDC, Nagaland.

31) Dimapur (Nagaland) 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.

32) 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 co-

ordination with SLDC, Nagaland.

33) 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 co-


34) 66 kV Bus at Khiphire Sub-Station shall be charged through any one of

3X6.5 MVA ICT at Khiphire Sub-Station.

35) Khiphire Sub-Station shall extend power to Likhimro Power Station

through 66 kV Khiphire – Likhimro line.

36) 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.

37) 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.

38) This sub-system may also be synchronized with Island E at Dimapur (PG)


39) Dimapur (PG) Sub-Station can also receive power form Mariani Sub-

Station through 132 kV S/C Mariani – Golaghat – Bokajan - Dimapur line.

40) 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 73

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. Presently, there is phase sequence problem

at Dullavcherra. Early rectification of this problem will help early

restoration of the system through this procedure.

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 73

Sub-system#1

Page 34 of 73

6.1.1.2 Restoration of sub-system #2 This sub-system consists of BTPS, Gelephu, Agia, Dhaligaon, Barnagar,

Nalbari, Rangia, Sipajhar, Sarusajai, Kahilipara and Langpi. Restoration

procedure for this sub-system is as follow :-

1) Power required for this sub-system shall be taken from Birpara (ER) Sub-

Station to Salakati (NER) Sub-Station through any one of 220 kV D/C

Birpara – Salakati lines. 132 kV Bus at Salakati Sub-Station shall be

charged through any one of 2X50 MVA ICT at Salakati Sub-Station.

Salakati Sub-Station shall extend power to Gelephu (Bhutan) Sub-Station

through 132 kV S/C Salakati – Gelephu International Line. Load at Gelephu

(Bhutan) shall be connected in co-ordination with NLDC, Bhutan.

2) If power received from Birpara (ER) Sub-Station delayed, then the

following procedure can be adopted :-

Bongaigaon (NER) Sub-Station shall receive power from New Siliguri (ER)

Sub-Station through any one of 400 kV D/C New Siliguri – Bongaigaon

lines. Any one of 220 kV Bus(s) at Salakati Sub-Station shall be charged

through 315 MVA ICT at Bongaigaon Sub-Station.

3) Salakati (PG) Sub-Station shall extend power to BTPS (Assam) Sub-Station

through any one of 220 kV D/C Salakati – BTPS lines.

4) 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.

5) 132 kV Bus at BTPS Sub-Station shall be charged through any one of 2X80

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 co-ordination with

SLDC, Assam.

6) 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.

7) 132 kV S/C Rangia – Barnagar line shall be closed.

Page 35 of 73

8) 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 co-


9) Agia (Assam) Sub-Station shall extend power to Sarusajai (Assam) Sub-

Station through 220 kV S/C Agia – Sarusajai or 132 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.

10) 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.

11) Sarusajai Sub-Station shall extend power to Langpi (Assam) Power Station

through any one of 220 kV D/C Sarusajai – Langpi lines.

12) 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.

13) 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 73

Sub-system #2

Page 37 of 73

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 co-

ordination 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 220 kV S/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 73

ISLAND B

Page 39 of 73

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 co-

ordination 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.

Page 40 of 73

8) This island shall be synchronized with sub-system #2 at Umtru (Meghalaya)

through any one of 132 kV D/C Umtru – Sarusajai lines or through any one of

132 kV D/C Umtru – Kahilipara 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 Power

Station through NEHU & Umiam Sub-Stations 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 and extend power to Umiam St

I Power Station through NEHU & Umiam Sub-Stations for brining

generation.

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.

Page 41 of 73

ISLAND C

Page 42 of 73

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 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 co-

ordination with SLDC, Tripura.

11) Dhalabil Sub-Station shall extend power to Kamalpur Sub-Station through 132

kV S/C Dhalabil –Kamalpur line. Load at Kamalpur shall be connected in co-


Page 43 of 73

12) Kamalpur Sub-Station shall extend power to P K Bari Sub-Station through 132

kV S/C Kamalpur – P K Bari line. Load at P K Bari shall be connected in co-


13) P K Bari Sub-Station shall extend power to Dharmanagar Sub-Station through

132 kV S/C P K Bari – Dharmanagar line. Load at Dharmanagar shall be

connected in co-ordination with SLDC, Tripura.

14) Dharmanagar Sub-Station shall extend power to Dullavcherra (Assam) Sub-

Station through 132 kV S/C Dharmanagar – Dullavcherra line. Dullavchera

shall extend start up power to Adamtila. Load at Dullavcherra shall be


15) P K Bari Sub-Station shall extend power to Kumarghat Sub-Station through

132 kV S/C P K Bari – Kumarghat line.

16) AGTPP shall extend power to Kumarghat Sub-Station through 132 kV S/C

AGTPP – Kumarghat line.

17) Kumarghat Sub-Station shall extend power to Aizawl Sub-Station through 132

kV S/C Kumarghat – Aizawl line.

18) Aizawl (PG) Sub-Station shall extend power to Zimabawk & Longmol

(Mizoram) Sub-Station through 132 kV S/C Aizawl – Zimabawk & 132 kV

Aizawl – Longmol lines. Load at Zimabawk & Longmol (Mizoram) shall be

connected in co-ordination with SLDC, Mizoram.

19) P K Bari Sub-Station shall extend power to Kailashar Sub-Station through 132

kV S/C P K Bari – Kailashar line. Load at Kailashar shall be connected in co-

ordination with SLDC, Agartala.

20) P K Bari Sub-Station shall extend power to Ambassa Sub-Station through 132

kV S/C P K Bari – Ambassa line. Load at Ambassa shall be connected in co-

ordination with SLDC, Agartala. 132 kV Baramura – Gamaitila - Ambassa lines

shall be closed.

21) If required, Bus Reactor (Annex III) at Kumarghat and Aizawl Sub-Stations

shall be taken into service to contain voltage.

22) This island may be synchronized with sub-system#1 at Aizwal (PG) through

132 kV S/C Kolasib – Aizwal line

23) This island shall be synchronized with Island E at Aizwal (PG) through 132 kV

S/C Jiribam – Aizwal line.

Page 44 of 73

Note : SLDC, Tripura and Mizoram shall co-ordinate with NERLDC before

connecting loads.

Note : If Black start of units of this Island is not possible then power shall be

received from the following sources:-

i. From sub system #1, Kumarghat Sub-Station can receive power from

Badarpur (PG) through 132 kV S/C Badarpur – Kumarghat line. Start

up power for bringing machines of AGTPP can receive power from

Kumarghat Sub-Station through 132 kV Kumarghat – AGTPP line.

ii. From sub system#1, Aizawl (PG) Sub-Station can receive power from

Kolasib Sub-Station through 132 kV S/C Aizawl – Kolasib line.

iii. From Island E, Aizawl Sub-Station can receive power from Jiribam

(PG) Sub-Station through 132 kV S/C Jiribam – Aizawl line.

Page 45 of 73

ISLAND D

Page 46 of 73

6.1.5 Restoration of Island E:

This Island consists of Loktak, Manipur and Pailapool. Restoration procedure

for this Island is as follow :-

i) Loktak (NHPC) Power Station shall black start and charge 132 kV Bus.

ii) Loktak Power Station shall extend power to Imphal (PG) and Ningthoukong

Sub-Stations through 132 kV S/C Loktak – Imphal and 132 kV S/C Loktak –

Ninghthoukong lines respectively. Load at Ningthoukong shall be connected in

co-ordination with SLDC, Manipur. Loktak Power Station shall bring and

synchronize other machines.

iii) Imphal (PG) Sub-Station shall extend power to Imphal (Manipur) Sub-Station

through 132 kV S/C Imphal – Imphal line. Load at Imphal (Manipur) shall be

connected in co-ordination with SLDC, Manipur.

iv) Ningthoukong Sub-Station shall extend power to Churachandpur Sub-Stations

through 132 kV S/C Ningthoukong – Churachandpur line. Load at

Churachandpur shall be connected in co-ordination with SLDC, Manipur. 132

kV S/C Ningthoukong – Imphal (Manipur) lines shall be closed.

v) Imphal (Manipur) Sub-Station shall extend power to Karong and Yangangpokpi

(Manipur) Sub-Stations through 132 kV S/C Imphal – Karong line and 132 kV

S/C Imphal – Yangangpokpi lines. Load at Karong and Yangangpokpi shall be


vi) Loktak Power Station shall extend power to Jiribam (PG) & Rengpang

(Manipur) Sub-Station through 132 kV S/C Loktak – Jiribam and 132 kV S/C

Loktak – Rengpang lines respectively. Load at Rengpang shall be connected in

co-ordination with SLDC, Manipur.

vii) Jiribam (PG) Sub-Station shall extend power to Pailapool ( Assam) Sub-Station

through 132 kV S/C Jiribam – Pailapool line. Load at Pailapool shall be

connected in co-ordination with SLDC, Assam and start up power to be

extended to Baskandi Power Station for bringing of their machines.

viii) 33 kV Bus at Jiribam (PG) Sub-Station shall be charged through 1X6.3 MVA

ICT at Jiribam (PG) Sub-Station. Load at Jiribam shall be connected in co-

ordination with SLDC, Manipur.

ix) This island shall be synchronized with sub-system #1 at Haflong (PG) through

132 kV S/C Haflong – Jiribam line.

Page 47 of 73

Note: SLDC, Assam and Manipur shall co-ordinate with NERLDC before

connecting loads.

Note: If Black start at Loktak Power Station is not possible then power shall be

received from the following sources:-

i. From sub system #1, Imphal (PG) Sub-Station can receive power from

Dimapur Sub-Station through 132 kV S/C Dimapur – Imphal line.

Imphal Sub-Station shall extend power to Loktak Power Station through

132 kV S/C Imphal - Loktak line.

ii. From sub system #1, Jiribam Sub-Station can receive power from

Badarpur Sub-Station through 132 kV S/C Jiribam – Badarpur line.

iii. From sub system #1, Jiribam Sub-Station can receive power Haflong

Sub-Station through 132 kV S/C Jiribam – Haflong line.

iv. From Island D, Jiribam Sub-Station can receive power Aizawl (PG)

Sub-Station through 132 kV S/C Jiribam – Aizawl line.

By the above procedures NER Grid can be restored fully from the

total collapsed condition, after utilizing ER power as well as black start

facilities available in various power stations in NER. After building up

of NER Grid, balance elements shall be restored at the earliest.

Page 48 of 73

ISLAND E

Page 49 of 73

6.2 Restoration of NER Grid after total collapse, when power from ER is

not available For restoration of NER Grid from total collapse condition, when power from ER is

not available, the following Islands are to be built up in parallel:-

F. Island consisting of Tripura, AGTPP, Kumarghat, Mizoram System,

Badarpur, Panchgram, Khliehriat, Khandong, Kopili, Haflong, Misa and

Samaguri

G. Island consisting of Loktak, Manipur, Jiribam, Pailapool, Imphal,

Dimapur, Doyang and Nagaland

H. Island consisting of NTPS , LTPS , Mariani, Dibrugarh and Tinsukia

I. Island consisting of Meghalaya with Kahilipara and Sarusajai

Page 50 of 73

6.2.1 Restoration of Island F This Island consists of Tripura, AGTPP, Kumarghat, Mizoram System,

Badarpur, Panchgram, Khliehriat, Khandong, Kopili, Haflong, Misa and

Samaguri . The restoration of this Island is the same as the procedure followed

for Island D as well as the following procedures:-

1) Khandong (NEEPCO) Power Station shall black start one of three machines &

charge 132 kV Bus. Khandong Power Station shall charge 33 kV Bus through

any one of 1X16+1X7.5 MVA Transformers. Khandong shall extend power to

Umrangshoo (Assam) Sub-Station through 33 kV S/C of Khandong –

Umrangshoo line. Load at Umrangsho shall be connected in co-ordination with

SLDC, Assam.

2) Khandong Power Station shall extend power to Haflong (PG) Sub-Stations

through 132 kV Khandong – Haflong line.

3) Haflong (PG) Sub-Station shall extend power to Haflong (Assam) Sub-Stations

through 132 kV Haflong (PG) – Haflong (Assam) line. Load at Haflong shall be

connected in co-ordination with SLDC, Assam (Formation of Island Khandong)

4) Kumarghat (PG) Sub-Station shall extend power to Badarpur (PG) Sub-Station

through 132 kV S/C Kumarghat - Badarpur line.

5) 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 (Assam) Sub-Station through 132 kV S/C Panchgram

– Sreekona line. Load at Panchgram and Sreekona shall be connected in co-


6) Aizwal (PG) Sub-Station shall extend power to Kolasib (Mizoram) Sub-Station

through 132 kV S/C Aizwal - Kolasib line. Load at Kolasib shall be connected

in co-ordination with SLDC, Mizoram.

7) Kolasib Sub-Station shall extend power to Bairabi (Mizoram) Power Station for

survival/auxiliary power through 66 kV Kolasib – Bairabi line.

8) Badarpur Sub-Station shall extend power to Khliehriat (PG) Sub-Station

through 132 kV S/C Badarpur – Khliehriat line.

9) Island D along with load at Panchgram, Sreekona & Kolasib shall be

synchronized with Island C at Khliehriat (PG) through any one of 132 kV D/C

Khliehriat – Khliehriat lines.

Page 51 of 73

10) Island C and D along with load at Panchgram, Sreekona & Kolasib shall be

synchronized with Island Khandong at Khandong Power Station through 132

kV S/C Badarpur – Jiribam line. Khandong Power Station shall bring and

synchronize other machines.

11) Island C, D and Khandong along with load at Panchgram, Sreekona & Kolasib

shall be synchronized with Island G at Badarpur (PG) through 132 kV S/C

Badarpur – Jiribam line.

12) Khandong Power Station shall extend power to Kopili (NEEPCO) Power

Station through any one of 132 kV D/C Khandong – Kopili lines. Kopili shall

charge any one of 220 kV Bus(s) through 160 MVA ICT at Kopili Power

Station. Kopili Power Station shall bring machines and synchronize. Kopili

Power Station shall increase generation in co-ordination with NERLDC.

13) Kopili Power Station shall extend power to Misa (PG) Sub-Station through any

one of 220 T/C Kopili – Misa lines.

14) Misa Sub-Station shall extend power to Samaguri (Assam) Sub-Station through

any one of 220 kV D/C Misa – Samaguri lines. Load at Samaguri shall be

connected in co-ordination with SLDC, Assam. Bus Reactor (at Annx III) at

Samaguri Sub-Station shall be taken into service to contain voltage.

Note : SLDC, Tripura, Mizoram and Assam shall co-ordinate with

NERLDC before connecting loads to their systems.

Note : If Black start of units of this Island is not possible then start up power

shall be received from the following Islands :-

i. From Island G, Badarpur Sub-Station can receive power from Jiribam

(PG) Sub-Station through 132 kV S/C Badarpur – Jiribam line.

ii. From Island G, Aizawl (PG) Sub-Station can receive power from

Jiribam Sub-Station through 132 kV S/C Aizawl – Jiribam line.

iii. From Island I, Panchgram Sub-Station can receive power from

Lumsnong (Meghalaya) Sub-Station through 132 kV S/ Lumsnong –

Panchgram line.

Page 52 of 73

6.2.2 Restoration of Island G This Island consists of Loktak, Manipur System, Jiribam, Pailapool, Imphal,

Dimapur, Doyang and Nagaland. The restoration procedure of this Island is

the same as adopted for Island E plus the following procedure:

1) Doyang Power Station shall black start any one of three machines & charge

132 kV Bus and extend power to Mokakchung Sub-Station. Otherwise they

should wait for extension of power from Dimapur (PG) Sub-Station.

2) Imphal (PG) Sub-Station shall extend power to Dimapur (PG) Sub-Station

through 132 S/C kV Imphal - Dimapur line. Any one of 220 bus(s) at

Dimapur Sub-Station shall be charged through any one of 2x100 MVA ICT at

Dimapur Sub-Station.


Station through 132 kV S/C Dimapur – Dimapur line. Load at Dimapur

(Nagaland) shall be connected in co-ordination with SLDC, Nagaland.

4) Dimapur (Nagaland) Sub-Station shall extend power to Kohima Sub-Station

through 132 kV S/C Dimapur – Kohima line. Load at Kohima shall be


5) 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 co-


6) 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 co-


7) 66 kV Bus at Khiphire Sub-Station shall be charged through any one of 3X6.5

MVA ICT at Khiphire Sub-Station.

8) Khiphire Sub-Station shall extend power to Likhimro Power Station through

66 kV Khiphire – Likhimro line.

9) Dimapur (PG) Sub-Station shall extend power to Doyang (NEEPCO) Power

Station through any one of 132 kV D/C Dimapur – Doyang lines. Doyang

Power Station shall synchronize their generation in co-ordination with

NERLDC.


Station through 132 kV S/C Doyang – Mokukchung line. Load at

Mokokchung shall be connected in co-ordination SLDC, Nagaland.

Page 53 of 73

11) This island shall be synchronized with Island F at Dimapur (PG) through any

one of 220 kV D/C Dimapur – Misa lines.

12) This island shall be synchronized with Island H at Dimapur (PG) through 132

kV S/C Mariani - Dimapur line.

Note : SLDC, Nagaland and Manipur shall co-ordinate with NERLDC before

connecting loads to their systems

Note : If black start of units of this Island is not possible then the start up power

can be received from the following Islands :-

i. From Island H, Dimapur (PG) Sub-Station can receive power form

Mariani Sub-Station through 132 kV S/C Mariani - Dimapur line.

ii. From Island F, Jiribam Sub-Station can receive power from Badarpur

Sub-Station through 132 kV S/C Badarpur - Jiribam line.

iii. From Island F, Dimapur (PG) Sub-Station can also receive power

from Misa (PG) Sub-Station through any one of 220 kV D/C Misa -

Dimapur lines.

Page 54 of 73

6.2.3 Restoration of Island H This Island consists of NTPS, LTPS, Mariani, Dibrugarh and Tinsukia. The

restoration procedure of this Island is same as that the restoration procedure

for Island B in addition to the following :-

1) LTPS shall extend power to Mariani (Assam) Sub-Station through 132 kV S/C

LTPS – Mariani line. Load at Mariani shall be connected in co-ordination with

SLDC, Assam. Any one of 220 kV Bus (s) at Mariani Sub-Station shall be

charged through any one of 2x100 MVA ICT at Mariani Sub-Station.

2) This island shall be synchronized with Island F at Mariani (Assam) through 220

kV S/C Samaguri - Mariani line. Bus Reactors (at annex III) at Mariani Sub-

Stations shall be taken into service to contain voltage.

Page 55 of 73

6.2.4. Restoration of Island I This Island consists of Meghalaya System with Kahilipara and Sarusajai.

The restoration of this island is same as the restoration procedure of Island C

along with the following:

1) Umtru (Meghalaya) Power Station shall extend power to Sarusajai (Assam)

Sub-Station through any one of 132 kV D/C Umtru – Sarusajai lines. Load at

Sarusajai shall be connected in co-ordination with SLDC, Assam and

Meghalaya.

2) Umtru (Meghalaya) Power Station shall extend power to Kahilipara (Assam)

Sub-Station through any one of 132 kV D/C Umtru – Kahilipara lines. Load at

Kahilipara shall be connected in co-ordination with SLDC, Assam and

Meghalaya.

After synchronization of the above Islands (F, G, H and I) together at

Badarpur (PG), Khliehriat (PG), Dimapur (PG) and Mariani (Assam) Sub-

Stations, balance elements of the syatem shall be restored at the earliest to

build up total NER Grid. To contain voltage, charging of 400 kV lines and

220 kV lines shall be avoided initially as the Grid may not absorb any jerk.

NERLDC shall co-ordinate with all ISGS to maximize their generation and

SLDCs to maintain drawl from the Grid to avoid any load generation

mismatch. Restoration of rest of the Grid consisting of Balipara, Khupi, Kimi,

Gohpur, Nirjuli, Itanagar, SMS, Ranganadi, Ziro, Daporijo, Along, North

Lakhimpur , Dhemaji, Majuli, Rangia, Rowta, Sipajhar, Depota, Barnagar,

Nalbari, Dhaligaon, BTPS, AGBPP and Deomali are as follow :

1) Mariani Sub-Station shall extend power to AGBPP (NEEPCO) through

400 kV S/C Mariani – AGBPP line (charged at 220 kV). AGBPP shall

synchronize units and extend power to Deomali Sub-Station through 220

kV S/C AGBPP – Deomali line. Load at Deomali shall be connected in

co-ordination with SLDC, Arunachal Pradesh.

2) Samaguri Sub-Station shall extend power to Balipara Sub-Station through

220 kV S/C Samaguri – Balipara line. Any one of 220 kV Bus(s) at

Balipara Sub-Station shall be charged through any one of 2X50 MVA

ICT.

Page 56 of 73

3) Balipara Sub-Station shall extend power to Khupi & Kimi through 132 kV

S/C Balipara – Khupi - Kimi. Load at Khupi and Kimi shall be connected

in co-ordination with SLDC, Arunachal Pradesh.

4) Balipara Sub-Station shall also extend power to Gohpur Sub-Station

through 132 kV S/C Balipara – Gohpur line. Load at Gohpur shall be


5) Gohpur Sub-Station shall extend power to North Lakhimpur Sub-Station

through 132 kV S/C Gohpur – North Lakhimpur line. North Lakhimpur

Sub-Station shall extend power to Dhemaji & Majuli Sub-Stations through

132 kV S/C North Lakhimpur – Dhemaji & 132 kV North Lakhimpur -

Majuli lines respectively. Load at North Lakhimpur, Dhemaji & Majuli

shall be connected in co-ordination with SLDC, Assam.

6) Gohpur Sub-Stations shall extend power to Nirjuli (PG) Sub-Stations

through 132 kV S/C Gohpur – Nirjuli line. Nirjuli Sub-Station shall charge

33 kV Bus through any one of 1 × 10 MVA and 1×16 MVA ICT. Nirjuli

Sub-Station shall extend power to Itanagar Sub-Station through any one of

four nos. 33 kV lines. Load at Itanagar shall be connected in co-ordination

with SLDC, Arunachal Pradesh.

7) Nirjuli Sub-Station shall extend power to Ranganadi (NEEPCO) Power

Station through 132 kV S/C Nirjuli – SMS - Ranganadi line. Load at SMS

shall be connected in co-ordination with SLDC, Arunachal Pradesh.

8) Ranganadi Power Station shall extend power to Along (Arunachal) Sub-

Station through 132 kV S/C Ranganadi – Ziro – Daporijo – Along line.

Loads at Ziro, Daporijo and Along (Arunachal) shall be connected in co-


9) Kahilipara Sub-Station shall extend power to Rangia and Sisugram

(Assam) Sub-Stations through 132 kV S/C Kahilipara – Rangia line and

132 kV S/C Kahilipara – Sisugram line respectively. Loads at Rangia and

Sisugram shall be connected in co-ordination with SLDC, Assam.

10) Rangia Sub-Station shall extend power to Rowta (Assam) and Depota Sub-

Stations through 132 kV S/C Rangia – Sipajhar - Rowta – Depota line.

Depota Sub-Station can also draw power from Balipara (PG) Sub-Station

through 132 kV S/C Balipara – Depota line. Loads at Sipajhar, Rowta and

Depota shall be connected in co-ordination with SLDC, Assam.

Page 57 of 73

11) Rangia Sub-Station shall extend power to Barnagar, Nalbari and

Dhaligaon (Assam) Sub-Stations through 132 kV S/C Rangia – Barnagar

line and 132 kV S/C Rangia – Nalbari - Dhaligaon line respectively.

Loads at Nalbari, Barnagar and Dhaligaon shall be connected in co-


12) Dhaligaon Sub-Station shall extend power to BTPS (Assam) Sub-Station

through any one of 132 kV D/C Dhaligaon – BTPS lines.

13) Balipara Sub-Station may charge one of 400 kV Bus(s) through 315 MVA

ICT. Tertiary Reactors (at Annex III) at Balipara Sub-Station shall be

taken into service to contain voltage. Balipara Sub-Station can charge any

one 400 kV D/C Balipara – Ranganadi lines if voltage permits. If required,

Bus Reactor at Balipara Sub-Station and Ranganadi Power Station may be

taken into service to contain voltage.

14) Misa (PG) Sub-Station shall charge 400 kV Bus through 315 MVA ICT.

Tertiary Reactors (at Anxx III) at Misa Sub-Station shall be taken into

service to contain voltage. Any one of 400 kV D/C Misa – Balipara lines

shall be closed. If required, Bus Reactor at Misa Sub-Station may be taken

into service to contain voltage.

15) Misa Sub-Station shall extend power to Byrnihat (Meghalaya) Sub-Station

through any one of 220 kV D/C Misa – 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-

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 co-

ordination with SLDC, Meghalaya.

16) Ranganadi Power Station shall charge the 132 kV Bus through any one of

2 x 360 MVA ICT. Ranganadi Power Station shall synchronize machines,

if required.

17) Any one of 220 kV D/C Samaguri – Sarusajai lines shall be closed.

Sarusajai Sub-Station shall extend power to Agia and Boko Sub-Stations

through 220 kV Sarusajai – Boko - Agia line. Load at Agia and Boko shall

be connected in co-ordination with SLDC, Assam.

Page 58 of 73

18) Agia Sub-Station shall extend power to BTPS Sub-Station through 220 kV

BTPS – Agia line. Presently one circuit of 220 kV BTPS –Agia line is

available.

19) BTPS Sub-Station shall extend power to Salakati (PG) Sub-Station

through any one of 220 kV D/C BTPS – Salakati lines. Salakati Sub-

Station shall charge 132 kV Bus through any one of 2X50 MVA ICT.

Salakati Sub-Station shall extend power to Gelephu (Bhutan) through 132

kV Salakati – Gelephu Line (International Line). Load at Gelephu

(Bhutan) shall be connected in co-ordination with NLDC, Bhutan.

20) Bongaigaon Sub-Station shall charge 400 kV Bus through 315 MVA ICT.

If required, Tertiary Reactors and Bus Reactor at Bongaigaon may be

taken into service.

21) Whenever ER power is available, NER Grid shall be synchronized with

ER Grid at Salakati through any one of 220 kV D/C Birpara – Salakati

lines. If synchronization with ER Grid through any line of 220 kV D/C

Birpara – Salakati lines delayed, NER Grid shall be synchronized with ER

Grid at Bongaigaon through any one of 400 kV D/C New Siliguri –

Bongaigaon lines.

Note : All SLDCs shall follow NERLDC’s real time advice before

connecting the loads. NERLDC shall closely monitor the

load-generation pattern of the Grid and shall release the

load stepwise base on the generation availability.

Page 59 of 73

6.3 Restoration of 132 kV Network, after partial collapse, comprising of

Nagaland, Manipur, South Assam, Mizoram, Tripura and

Meghalaya

This system shall be restored as per the procedures adopted for the restoration of

Island C, Island D and Island E as well as the following procedure:

1) 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 Dimapur Sub-

Station shall be charged through any one of 2X100 MVA ICT at Dimapur Sub-

Station.

2) Kopili (NEEPCO) Power Station shall charge 132 kV Bus through 160 MVA

ICT. 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 and synchronize.

3) Khandong Power Station shall charge 33 kV Bus through any one of 1X16+1X7.5

MVA Transformers. Khandong Power Station 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.

4) Khandong (NEEPCO) Power Station shall extend power to Haflong (PG) and

Khliehriat (PG) Sub-Stations through 132 kV S/C Khandong – Haflong and any

one of 132 kV D/C Khandong - Khliehriat lines respectively.

5) 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.

6) Part of this system shall be synchronized with Island C at Khliehriat (PG) through

any one of 132 kV D/C Khliehriat – Khliehriat lines.

7) Khliehriat (PG) Sub-Station shall extend power to Badarpur (PG) Sub-Station

through 132 kV S/C Khliehriat – Badarpur line.

8) Badarpur (PG) Sub-Station shall extend power to Panchgram (Assam) & Kolasib

(Mizoram) Sub-Stations through 132 kV S/C Badarpur – Panchgram & 132 kV

Badarpur – Kolasib lines. Load at Panchgram (Assam) & Kolasib (Mizoram) shall

be connected in co-ordination with SLDC, Assam & Mizoram.

Page 60 of 73

9) Panchgram (Assam) Sub-Station shall extend power to Sreekona (Assam) Sub-

Station through 132 kV S/C Panchgram –Sreekona line. Load at Sreekona

(Assam) shall be connected in co-ordination with SLDC, Assam.

10) Part of this system shall be synchronized with Island D at Badarpur (PG) through

132 kV S/C Kumarghat – Badarpur line.


Station through 132 kV S/C Dimapur – Dimapur line. Load at Dimapur shall be


12) Dimpur (Nagaland) 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.

13) Kohima (Nagaland) Sub-Station shall extend power to Meluri Sub-Station

through 132 kV S/C Kohima – Meluri line. Load at Meluri shall be connected in

co-ordination with SLDC, Nagaland.

14) Meluri (Nagaland) Sub-Station shall extend power to Khiphire Sub-Station

through 132 kV S/C Meluri – Khiphire line. Load at Khiphire shall be connected



MVA ICT at Khiphire.

16) Khiphire Sub-Station shall extend power to Likhimro through 66 kV Khiphire –

Likhimro line.


Station through any one of 132 kV D/C Dimapur – Doyang lines. Doyang Power

Station shall bring machines, if required and synchronize.


Station through 132 kV S/C Doyang – Mokukchung line. Load at Mokokchung

shall be connected in co-ordination with SLDC, Nagaland.

19) This syatem shall be synchronized with Island E at Dimapur (PG) through 132 kV

S/C Dimapur – Imphal line.

Note : SLDC, Nagaland, Manipur, Assam, Tripura, Mizoram and Meghalaya

shall co-ordinate with NERLDC, during the restoration period, for

connecting loads.

Page 61 of 73

6.4 Restoration of 132 kV Network after partial collapse comprising of

Nagaland System, Manipur System (except Jiribam) and Loktak :

Restoration of this system is as follows :- 1) 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 Dimapur Sub-

Station shall be charged through any one of 2X100 MVA ICT at Dimapur Sub-

Station.


Station through 132 kV S/C Dimapur – Dimapur line.


Station through 132 kV S/C Dimapur – Dimapur line. Load at Dimapur shall be


4) Dimpur (Nagaland) Sub-Station shall extend power to Kohima Sub-Station

through 132 kV S/C Dimapur – Kohima line. Load at Kohima shall be connected


5) Kohima (Nagaland) Sub-Station shall extend power to Meluri Sub-Station

through 132 kV S/C Kohima – Meluri line. Load at Meluri shall be connected in

co-ordination with SLDC, Nagaland.

6) Meluri (Nagaland) Sub-Station shall extend power to Khiphire Sub-Station

through 132 kV S/C Meluri – Khiphire line. Load at Khiphire shall be connected



MVA ICT at Khiphire.

8) Khiphire Sub-Station shall extend power to Likhimro through 66 kV Khiphire –

Likhimro line.


Station through any one of 132 kV D/C Dimapur – Doyang lines. Doyang Power

Station shall bring machines, if required and synchronize.


Station through 132 kV S/C Doyang – Mokukchung line. Load at Mokokchung

shall be connected in co-ordination with SLDC, Nagaland.

11) Loktak (NHPC) Power Station shall black start and charge 132 kV Bus.

Page 62 of 73

12) Loktak Power Station shall extend power to Imphal (PG), Ningthoukong,

Rengpang Sub-Stations through 132 kV S/C Loktak – Imphal, 132 kV S/C Loktak

– Ninghthoukong and 132 kV S/C Loktak – Rengpang lines respectively. Load at

Ningthoukong and Rengpang shall be connected in co-ordination with SLDC,

Manipur. Loktak Power Station shall bring and synchronize other machines.

13) Imphal (PG) Sub-Station shall extend power to Imphal (Manipur) Sub-Station

through 132 kV S/C Imphal – Imphal line. Load at Imphal (Manipur) shall be


14) Imphal (Manipur) Sub-Station shall extend power to Karong and Yangangpokpi

Sub-Stations through 132 kV S/C Imphal – Karong and 132 kV S/C Imphal –

Yangangpokpi lines. Load at Karong and Yangangpokpi (Manipur) shall be

connected in co-ordination with SLDC, Manipur. 132 kV S/C Ningthoukong –

Imphal lines shall be closed.

15) This system shall be synchronized with Rest of NER Grid at Dimapur (PG)


Note : If black start of Loktak (NHPC) Power Station units delayed, then start up

power required for bringing Loktak machines shall be received from the

follwing sources :-

i. Dimapur (PG) Sub-Station shall extend power to Imphal (PG) Sub-Station


ii. Imphal (PG) Sub-Station shall extend power to Imphal (Manipur) Sub-

Station through 132 kV S/C Imphal – Imphal line.

iii. Imphal (PG) Sub-Station shall extend power to Loktak Power Station

through 132 kV S/C Imphal – Loktak line. Loktak shall synchronize their

machines after receiving start up power.

iv. Loktak Power Station shall extend power to Ningthoukong Sub-Station

through 132 kV S/C Loktak – Ningthoukong line.

Note: SLDC, Nagaland and Manipur shall co-ordinate with NERLDC, during

the restoration period, for connecting loads.

Page 63 of 73

CHAPTER 7

REPORTING PROCEDURES 7.1 Introduction

This chapter deals with reporting procedures in respect of Grid Incidents/Grid Disturbance in

the system to all Users/STU/CTU, NERRPC Secretariat and NLDC/NERLDC/SLDC. The

reporting procedure shall be in accordance with the relevant CEA Regulations.

7.2 Objective

The objective of this chapter is to define the Grid Incidents/Grid Disturbance to be reported,

the reporting route to be followed and information to be supplied to ensure consistent

approach to the reporting of Grid Incidents/Grid Disturbance.

7.3 Scope

This chapter covers all Users, STU, CTU, NERRPC Secretariat, NLDC, NERLDC and

SLDCs.

7.4 Responsibility

i) The NERLDC/SLDC shall be responsible for reporting Grid Incidents/Grid Disturbance to

the Users, SLDC/STU, CTU /NLDC/NERLDC/NERRPC Secretariat as the case may be.

ii) All Users, STU, CTU and the SLDC shall be responsible for collection and reporting of

all necessary data to NLDC, NERLDC and NERRPC Secretariat for reporting Grid

Incidents/Grid Disturbance analysis as the case may be.

7.4. Categorisation of Grid Incidents and Grid Disturbance based on severity of

trippings

The categorisation of Grid Iincidents and Grid Disturbances shall be as follows:-

7.4.1 Categorisation of Grid Incidents in increasing order of severity :-

Category GI-1 - Tripping of one or more power system elements of the Grid like a

Generator, Transmission Line, Transformer, Shunt Reactor, Series Capacitor and Static

VAR Compensator, which requires re-scheduling of Generation or Load, without total

loss of supply at a Sub-Station or loss of integrity of the Grid at 220 kV (132 kV in the

case of North-Eastern Region)

Page 64 of 73

Category GI-2 - Tripping of one or more power system elements of the Grid like a

Generator, Transmission Line, Transformer, Shunt Reactor, Series Capacitor and Static

VAR Compensator, which requires re-scheduling of Generation or Load, without total

loss of supply at a sub-station or loss of integrity of the Grid at 400 kV and above (220

kV and above in the case of North-Eastern Region).

7.4.2 Categorisation of Grid Disturbance in increasing order of severity :-

Category GD-1 - When less than ten per cent. of the antecedent Generation or load in a

Regional Grid is lost;

Category GD-2 - When ten per cent. to less than twenty percent of the antecedent

Generation or Load in a Regional Grid is lost.

Category GD-3 - When twenty per cent. to less than thirty per cent. of the antecedent

Generation or Load in a Regional Grid is lost;

Category GD-4 - When thirty per cent. to less than forty per cent. of the antecedent

Generation or Load in a Regional Grid is lost ;

Category GD-5 - When forty per cent. or more of the antecedent Generation or Load in

a Regional Grid is lost.

Explanation: For the purpose of categorisation of Grid Disturbances, percentage loss of

Generation or Load, which ever is higher shall be considered.

7.5 Reporting of Grid Disturbance

7.5.1 Any of the following Grid Incidents/ Grid Disturbance require for reporting

by NERLDC/Users, SLDC, STU, CTU :-

i) System Islanding/System Split

ii) Regional Black Out/Partial System Black Out

7.5.2 Written reporting of Grid Incidents/Grid Disturbance by Users, STU, CTU

and SLDC to NERLDC : -

In the case of a Grid Incident/Grid Disturbance which was initially reported

by a User, STU, CTU or SLDC to NERLDC orally, the User, STU, CTU,

SLDC will give a written report to NERLDC in accordance with this chapter.

NERLDC in turn give a report to NLDC.

Page 65 of 73

7.5.3 Written Reporting of Events by NERLDC to Users, STU, CTU and SLDC :-

In the case of an Grid Incident/Grid Disturbance which was initially reported

by NERLDC to Users, STU, CTU, SLDC, NLDC orally, the NERLDC will

give a written report to the Users, STU, CTU ,SLDC and NLDC in

accordance with this section.

7.5.4 NERLDC shall inform occurrence of the Grid disturbance to the constituents

immediately and to the NERPC at the earliest.

7.5.5 The Grid Disturbance resulting in failure of power supply to large areas in a

State shall also be reported by the NERLDC to CEA within twenty four hours

of the occurrence of the Grid Disturbance.

7.5.6 NERLDC shall also post on its website a brief Preliminary Grid Disturbance

Report, indicating the affected area or system, extent of outage and the likely

cause of initiation for the benefit of the constituents of the Region.

7.5.7 Form of Written Reports : -

A written report shall be sent to NLDC, NERLDC, a User, STU, CTU, SLDC,

as the case may be, in the reporting formats as devised by NERLDC and will

confirm the oral notification together with the following details of the event :-

i) Time and Date of Grid Incident/Grid Disturbance

ii) Location

iii Plant and/or Equipment directly involved

iv) Description and cause of incident/disturbance

v) Antecedent conditions of Load and Generation, including Frequency,

Voltage and the Flows in the affected area at the time of tripping including

Weather Condition prior to the Grid Iincident/Grid Disturbance

vi) Duration of interruption and Demand and/or Generation (in MW and

MWh) interrupted

vi) All Relevant system data including copies of records of all recording

instruments including Disturbance Recorder, Event Logger, DAS etc.

All operational data, including Disturbance Recorder and Event Logger

Reports, for analysing the Grid Incidents and Grid Disturbance and any

other data which in its view can be of help for analysing Grid Incident or

Page 66 of 73

Grid Disturbance shall be furnished by all the Entities within twenty four

hours to NERLDC and NERPC. No Entity shall block any

data/information required by NERLDC and NERRPC for maintaining

reliability and security of the Grid and for analysis of an event.

viii) Details of Relay Flags.

ix) Remedial measures.

7.6. Operational Data during Grid Incidents and Grid Disturbances

1.. NERLDC shall classify the Grid Incidents and Grid Disturbances according

to 7.4 of this procedure, analyse them and furnish periodic reports of Grid

Incidents and Grid Disturbances to NERPC which shall recommend

remedial measures to be taken on the Report of NERLDC to prevent

recurrences of such Grid Incidents and Grid Disturbances.

7.7. Operational Data Records

1. A record shall be kept of the number of Grid Incidents and Grid

Disturbances of various categories by the NERPC for each financial year.

2. A compendium of Grid Disturbances, indicating details such as the date and

time of the disturbance, the sequence of tripping, the cause, and the

Sequence of Restoration, remedial measures taken to avert recurrence of

such Incidents and Disturbances shall be maintained by NERPC.

Page 67 of 73

ANNEXURE - I

LIST OF POWER STATIONS WITH BLACK – START

FACILITIES ISGS : NEEPCO

START UP FACILITY

POWER

STATION

INSTALLED CAPACITY

(in MW)

UNIT TYPE SOURCE CAPACITY

(in kVA)

BLACK START

FACILITY

KHANDONG 2 X 25 HYDRO DG SET 1 X 250 YES

KHANDONG (KOPILI ST II) 25 HYDRO DG SET NA YES

KOPILI 4 X 50 HYDRO DG SET 1 X 600 YES

DOYANG 3 X 25 HYDRO DG SET 2 X 630 YES

RANGANADI 3 X 135 HYDRO DG SET 1 X 500 YES

AGTPP (R C NAGAR) 4 X 21 GAS DG SET 1 X 250 YES

AGBPP (KATHALGURI)

4 X 33.66+ 2 X 35+ 3 X 30

GAS + STEAM DG SET 1 X 950 + 1 X 250 NO

Page 68 of 73

ISGS : NHPC

STATE : ASSAM

START UP FACILITY

POWER

STATION

INSTALLED CAPACITY

(in MW)


(in kVA)

BLACK START

FACILITY

NAMRUP 3 X 23 + 12.5 + 30 + 22 GAS DG SET 844 YES

LAKWA 4 X 15 + 3 X 20 GAS NA NA YES #

ADAMTILA (IPP-DLF) 3 X 3 + 5 GAS GRID

POWER NA NO

BASKANDI 3 X 3.5 GAS GRID POWER NA NO

KARBI LANGPI 2 X 50 HYDRO DG SET 1 X 500 YES

# Black start facility is not functional presently

START UP FACILITY

POWER STATION

INSTALLED CAPACITY

(in MW)


(in kVA)

BLACK START

FACILITY

LOKTAK 3 X 35 HYDRO DG SET 2 X 315 YES

Page 69 of 73

STATE : MEGHALAYA

START UP FACILITY

POWER

STATION

INSTALLED CAPACITY

(in MW)


(in Volt)

BLACK START

FACILITY

UMIAM ST I 4 X 9 HYDRO BBaatttteerryy BBaannkk 5555 XX 22 YYEESS

UMIAM ST II 2 X 9 HYDRO BBaatttteerryy BBaannkk 5555 XX 22 YYEESS

UMIAM ST III 2 X 30 HYDRO BBaatttteerryy BBaannkk 5555 XX 22 YYEESS

UMIAM ST IV 2 X 30 HYDRO BBaatttteerryy BBaannkk 111100 XX 22..55 YYEESS

UMTRU 4 X 2.8 HYDRO BBaatttteerryy BBaannkk NN//AA YYEESS

STATE : TRIPURA

START UP FACILITY

POWER

STATION

INSTALLED CAPACITY

(in MW)


(in kVA)

BLACK START

FACILITY

GUMTI 3 X 5 HYDRO DG SET NA NO

BARAMURA 2 X 21 GAS DG SET 1 X 380 YES

ROKHIA 4 X 8 + 2 X 21 GAS DG SET 2 X 380 YES

Page 70 of 73

STATE : NAGALAND

START UP FACILITY

POWER

STATION

INSTALLED CAPACITY

(in MW)


(in kVA)

BLACK START

FACILITY

LIKIMRO 3 X 8 HYDRO DG SET NA NO

STATE : MIZORAM

START UP FACILITY

POWER

STATION

INSTALLED CAPACITY

(in MW)


(in kVA)

BLACK START

FACILITY

BAIRABI 4 X 5.7 HSD DG SET NA NO

Page 71 of 73

ANNEXURE – II

LIST OF SUB-STATION WITH SYNCHRONISING

FACILITIES CTU : POWERGRID

SUB-STATIONS

VOLTAGE LEVEL (in kV)

SYNCHRONISING

FACILITY

DG SET

DETAILS (in kVA)

BONGAIGAON 400 YES 1 X 250

SALAKATI 220 YES 2 X 200

BALIPARA 400 YES 2 X 250

MISA 400 YES 2 X 250

DIMAPUR 220 YES 1 X 250

IMPHAL 132 YES 1 X 100

JIRIBAM 132 YES 1 X 70

HALFLONG 132 YES 1 X 63

AIZWAL 132 YES 1 X 63

KUMARGHAT 132 YES (NOT OPERATIONAL) 1 X 63

BADARPUR 132 YES 1 X 100

KHLIEHRIAT 132 YES 1 X 100

NIRJULI 132 YES 1 X 100

ZIRO 132 YES 1 X 100

Page 72 of 73

STATE : ASSAM

SUB-STATIONS


SYNCHRONISING

FACILITY

DG – SET DETAILS (in kVA)

BTPS 220 YES NO

SARUSAJAI 220 YES NO

SAMAGURI 220 YES (NOT OPERATIONAL)

NO

MARIANI 220 YES NO

TINSUKIA 220 YES NO

KAHELIPARA 132 YES 1 X 30

DEPOTA 132 YES (NOT OPERATIONAL) NO

STATE : TRIPURA

SUB-STATIONS


SYNCHRONISING

FACILITY (YES / NO)

DG – SET DETAILS (in kVA)

79 TILLA (AGARTALA) 132 YES 1 X 30

Page 73 of 73

ANNEXURE – III

LIST OF SHUNT REACTORS IN NER

UTILITY LOCATION VOLTAGE

LEVEL (in kV)

NAME OF THE LINE/BUS

CAPACITY (MVAR) TYPE

POWERGRID MISA 33 33 kV BUS 4 X 25 TERTIARY

POWERGRID MISA 400 400 kV BUS 1 X 50 BUS

POWERGRID MISA 400 KATHALGURI 1 X 50 LINE

POWERGRID MISA 400 MARIANI 1 X 50 LINE

POWERGRID BALIPARA 33 33 kV BUS 4 X 25 TERTIARY

POWERGRID BALIPARA 400 400 kV BUS 1 X 50 BUS

POWERGRID BALIPARA 400 BONGAIGAON I 1 X 63 LINE

POWERGRID BALIPARA 400 BONGAIGAON II 1 X 63 LINE

POWERGRID BALIPARA 400 RANGANADI I 1 X 50 LINE

POWERGRID BALIPARA 400 RANGANADI II 1 X 50 LINE

POWERGRID BONGAIGAON 400 NEW SILIGURI I 1 X 63 LINE

POWERGRID BONGAIGAON 400 NEW SILIGURI II 1 X 63 LINE

POWERGRID BONGAIGAON 400 BALIPARA I 1 X 50 LINE

POWERGRID BONGAIGAON 400 BALIPARA II 1 X 50 LINE

POWERGRID BONGAIGAON 400 400 kV BUS 2 X 50 BUS

POWERGRID BONGAIGAON 33 33 kV BUS 2 X 25 TERTIARY

POWERGRID AIZWAL 132 132 kV BUS 1 X 20 BUS

POWERGRID KUMARGHAT 132 132 kV BUS 1 X 20 BUS

NEEPCO RANGANADI 400 BALIPARA I 1 X 50 LINE

NEEPCO RANGANADI 400 BALIPARA II 1 X 50 LINE

AEGCL MARIANI 220 220 kV BUS 2 X 12.5 BUS

AEGCL SAMAGURI 220 220 kV BUS 2 X 12.5 BUS

TSECL DHARMANAGAR 132 132 kV BUS 2 X 2 BUS

Total 1196

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