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उत्तर पूर्वी क्षेत्रीय ग्रिड की
ब्लैक स्टाटट और पुनःस्थापन प्रक्रिया
BLACK START AND RESTORATION
PROCEDURES OF NER GRID
POWER SYSTEM OPERATION CORPORATION LTD (A wholly owned subsidiary of POWERGRID)
NORTH EASTERN REGIONAL LOAD DESPATCH CENTRE, Shillong
– 793006
DRAFT Procedures
Please submit the Comments by 25th Dec 2015
11th Revision Released Month:
Sl No Chapter Contex Page
1 Chapter 1 Introduction
2 Chapter 2 Black Start Facility
2.1 Existing Black Start Facilities
2.2 Survival/ Auxiliary Power requirement
2.3 Startup power requirement
2.4 Synchronizing facilities at Power Stations / major Sub- Stations
2.5 Shunt Reactors at major Power Station and Sub-Stations
3 Chapter 3 System Restoration Approach
3.1 General Guidelines
3.2 Initial Course of Action
3.3 Important Considerations during Restoration
3.4 Special Consideration in extending/availing start up power
3.5 DON’TS
4 Chapter 4 Broad Classification of North Eastern Regional Grid
4.1 400 / 220 kV Network of POWERGRID
4.2 220 / 132 kV Network of Assam System
4.3 220 / 132 kV Network of Arunachal Pradesh System
4.4 400 / 220 / 132 kV Southern part of network comprising of
Nagaland, Manipur, South Assam, Mizoram, Tripura, Meghalaya,
POWERGRID and NETC (North East Transmission Company)
INDEX
5 Chapter 5 Black Start & Restoration Procedures
5.1 Restoration of NER Grid after total collapse, when assistance
from Eastern Region (ER) Grid is available
5.2 Restoration of NER Grid after total collapse, when assistance
from Eastern Region (ER) Grid is not available
5.3 Restoration of 400 / 220 / 132 kV Network comprising of
southern part of network comprising of Manipur, South Assam,
Mizoram, Tripura, AGTPP and Palatana after partial collapse
6 Chapter 6 Reporting Procedures
6.1 Introduction
6.2 Objective
6.3 Scope
6.4 Responsibility
6.5 Categorisation of Grid Incidents and Grid Disturbance based on
severity of trippings
6.6 Reporting of Grid Disturbance
6.7 Form of Written Report
6.8 Operational Data during Grid Incidents and Grid Disturbances
6.9 Operational Data Records
7 Annexure 1 Additional of New Transmmission Element from the last Revision
8 Annexure 2 List of Sub-Stations having important loads
9 Annexure 3 Power Maps of NER Grid
10 Annexure 4 Network Diagram of NER Grid
CHAPTER 1: INTRODUCTION
1.0 North-Eastern Electrical Grid comprises of seven states viz Arunachal Pradesh, Assam, Manipur,
Meghalaya, Mizoram, Nagaland and Tripura. NER is basically a hydro dominant Region with
total installed capacity of 3161MW (central- 2008 MW & state- 1153 MW) connected to the Grid.
Some isolated generators (around 124MW) owned by the states are also being operated. After the
commercial operation of Palatana (726.6 MW), power position of NER has been improved
considerably. It is expected that NER will become a power hub of India in near future as lot of
power projects are in pipeline.
According to sections 28 and 29 of Electricity Act, 2003, NERLDC is the apex body to ensure
integrated operation of the power system in the NE region. Following regional entities come
under NERLDC’s jurisdiction:
Figure 1.1: Power Map of North Eastern
Region
Name of Regional Entity(ISGS)
AGBPP (NEEPCO)
AGTPP (NEEPCO)
AGTPP Ext(NEEPCO)
Doyang HEP (NEEPCO)
Kopili HEP (NEEPCO)
Kopili-2 HEP (NEEPCO)
Khandong HEP (NEEPCO
Ranganadi HEP (NEEPCO)
Loktak HEP (NHPC)
Palatana (OTPC)
In an integrated power system, disturbances of major / minor nature can occur under various
contingencies. Such disturbances can result in collapse of a part of the system or sometimes entire
system, requiring restoration of the affected system in the minimum possible time. In order to
achieve the same, it is therefore necessary to have a well laid down restoration procedure under
various conditions of partial black out and /or total black out of the system. In the event of a black
out, the initial moments are extremely important and it requires the right decision to be taken at
first instance for speedy restoration of the system. Any lapse or delay in taking the right initial
decision may prove to be very costly. Hence, it is of paramount importance that all the operating
personnel of Load Despatch Centres and the officials involved in grid operation should be
thoroughly conversant with the restoration procedure so as to minimise the time taken in
restoration of the system after partial /total black out. Further during the Restoration process the
system operators, Power station and Substation personnel must act in consonance to normalize the
grid.
IEGC 2010 clause no 5.8 (a) states that “Detailed plans and procedures for restoration of the
regional grid under partial/total blackout shall be developed by RLDC in consultation with
NLDC, all Users, STU,SLDC, CTU and RPC Secretariat and shall be reviewed / updated
annually”.As the network is expanding, in line with clause 5.8 (a & b) of IEGC, this Procedure
requires review and/or revision every year, based on which the Mock drill of the procedure for
Name of Regional Entity(Buyer)
Dept. of Power, Ar. Pradesh
APDCL
MSPDCL
MeECL
Power & Electricity Dept.,Mizoram
Dept. of Power,Nagaland
TSECL
Figure 1.2: List of Regional Entities of North Eastern
Region
different sub-systems shall be carried out by the constituents at least once in every six months
under intimation to NERLDC. Accordingly, NERLDC has been publishing the document on
“Black Start and Restoration Procedure of NER system” annually and last time it was published
on December 2014.
NERLDC has suggested the changes vide Letter dated 09/11/2015 and requested the feed back
from all utilities of NER. Based on the details of new elements added during this year (Annexure-
1) and the feedback received during Black start & restoration procedures Workshop held at
Guwahati on 04/02/2015 & communication, the updated version of the “Black Start and
Restoration Procedure in NER 2015” was approved by NERPC forum in the ______Operation
Co-ordination Committee meeting held on ____.
The procedures given in this document are general in nature and provide a guideline for the
restoration team at the time of disturbance. Depending on the availability of transmission
elements, generators and the category and extent of blackout, system operators should adopt the
best procedure suited for the situation.
Based on this document, as per IEGC clause 5.8(b) , NER constituents are advised to prepare
station wise detailed mock drill procedure/plan including switching instructions in their control
centres, so that the operators will have further clarity to ensure faster restoration in case of
contingencies.
CHAPTER 2: BLACK START FACILITY
2.1 Existing Black Start Facilities
A list of Generating Stations of NER (North Eastern Region) having black start facilities is
elaborated are as under
POWER
STATION OWNER
INSTALLED
CAPACITY
(in MW)
UNIT
TYPE
SOURC
E
CAPACIT
Y
(in kVA)
BLACK
START
FACILITY
KHANDONG NEEPCO 50 HYDRO DG SET 1 X 250 Yes
KOPILI
STAGE II NEEPCO 25 HYDRO NA NA Yes
KOPILI NEEPCO 200 HYDRO DG SET 1 X 437.5 Yes
DOYANG NEEPCO 75 HYDRO DG SET 2 X 625 Yes
RANGANADI NEEPCO 405 HYDRO DG SET
2 X
625(Oper
ational
one at a
time)
Yes
AGTPP
NEEPCO 84 GAS DG SET 1 X 500 Yes
AGTPP
Extension
NEEPCO 46 STEAM DG SET 1 X 600
No(Only
for
emergency
load)
Monarchak NEEPCO 67 GAS DG SET 1 X1000 Yes
PALATANA OTPC 726 Combin
e Cycle DG SET 2 X 750 Yes
Loktak NHPC 105 HYDRO DG SET 2 X 350
+ 1 X 500 Yes
NAMRUP Assam 119 GAS DG SET 3 X 673
Yes(Not
operational
)
KARBI
LANGPI Assam 100 HYDRO DG SET 1 X 500 Yes
UMIAM ST I Meghalaya 36 HYDRO Battery
Bank
(55 X 2)
V Yes
UMIAM ST II Meghalaya 18 HYDRO Battery
Bank
(55 X 2)
V Yes
UMIAM ST III Meghalaya 60 HYDRO Battery
Bank
(55 X 2)
V Yes
UMIAM ST IV Meghalaya 60 HYDRO Battery
Bank
(110 X
2.5)V Yes
UMTRU Meghalaya 11.2 HYDRO Battery
Bank
(110 X
2.5)V Yes
BARAMURA Tripura 59 GAS DG SET 2 X 380 Yes
ROKHIA Tripura 111 GAS DG SET 3 X 380 Yes
2.2 Survival/ Auxiliary Power requirement
Survival/Auxiliary power is required to avoid damages of some equipment 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 & Palatana units.
2.3 Startup power requirement
For restoration of Generating Unit, startup power is required for its auxiliaries. The requirement
of Startup power of various units is as follow:-
Gas - 2 % of Unit Capacity
Hydro - 1 % of Unit Capacity
Startup 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
Figure 2.1: Gerarating Stations of NER having Black Strat Facilities
large. However, startup power requirement for Hydro Generating Unit is less because of few
auxiliaries.
2.4 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
are as under:
SUB-STATIONS VOLTAGE
LEVEL
(in kV)
SYNCHRONISIN
G FACILITY
DG SET DETAILS
(in kVA)
POWERGRID
BONGAIGAON 400 Yes 1 X 250
SALAKATI 220 Yes 2 X 200
BALIPARA 400 Yes 2 X 250
MISA 400 Yes 2 X 250
SILCHAR 400 Yes 1 x 500
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
ASSAM
BTPS 220 Yes NO
MARIANI 132(220 not
functional)
Yes No
TINSUKIA 220 Yes No
KAHELIPARA 132(Not
Functional)
Yes 1 X 30
Meghalaya
2.5 Shunt Reactors at major Power Station and Sub-Stations
It is very essential to contain over voltage during the restoration process of a collapsed system.
During the early restoration process, lines are generally lightly loaded due to the restricted drawl
by the drawing utilities and voltage starts rising up in different buses as system size grows. Shunt
Reactors play a vital role to contain over voltage. List of Shunt Reactors available in NER Grid
are indicated as under:
Name of
Utility
Name of the
Line/Bus
Operating
Voltage in kV
Location Capacity (in
MVAR)
Line Reactors
POWERGRID 220 kV Misa - New
Mariani(PG) 220 Misa 50
POWERGRID 220 kV Misa-
Mariani(S) 220 Misa 50
POWERGRID 400 kV Balipara -
Bongaigaon I 400 Balipara 63
POWERGRID 400 kV Balipara -
Bongaigaon II 400 Balipara 63
POWERGRID 400 kV Balipara -
Bongaigaon III 400 Balipara 63*
POWERGRID 400 kV Balipara -
Bongaigaon IV 400 Balipara 63*
POWERGRID
400 kV Balipara
Biswanath Chariali
I
400 Balipara 50*
POWERGRID
400 kV Balipara -
Biswanath Chariali
II
400 Balipara 50*
POWERGRID 400 kV Bongaigaon
- New Siliguri I 400 Bongaigaon 63
Killing(Byrnihat) 220 Yes 1 x 250
Figure 2.2: Stations of NER having Synchronising Facilities
POWERGRID 400 kV Bongaigaon
- New Siliguri II 400 Bongaigaon 63
POWERGRID 400 kV Bongaigaon
- Azara 400 Bongaigaon 63*
POWERGRID 400 kV Bongaigaon-
Byrnihat 400 Bongaigaon 63*
POWERGRID 400 kV Bongaigaon
- Balipara I 400 Bongaigaon 50
POWERGRID 400 kV Bongaigaon
- Balipara II 400 Bongaigaon 50
POWERGRID 400 kV Balipara -
Bongaigaon III 400 Bongaigaon 63*
POWERGRID 400 kV Balipara -
Bongaigaon IV 400 Bongaigaon 63*
POWERGRID 400 k Silchar –
Palatana I 400 Silchar 50*
POWERGRID 400 kV Silchar –
Palatana II 400 Silchar 50*
POWERGRID 400 kV Silchar-
Byrnihat 400 Silchar 63*
POWERGRID 400 kV Silchar-
Azara 400 Silchar 63*
NEEPCO
400 kV Ranganadi
– Biswanath
Chariali I
400 Ranganadi 50*
NEEPCO
400 kV Ranganadi
– Biswanath
Chariali II
400 Ranganadi 50*
OTPC 400 kV Palatana –
Silchar I 400 Palatana
63(Not
convertible)
OTPC 400 kV Palatana –
Silchar II 400 Palatana
63(Not
Convertible)
ASSAM 400 kV Azara-
Silchar 400 Azara 63
Meghalaya 400 kV Byrnihat-
Silchar 400 Byrnihat 50
Bus Reactors
POWERGRID Bus Reactor 400 Misa 50
POWERGRID Bus Reactor I 400 Balipara 50
POWERGRID Bus Reactor II 400 Balipara 80
POWERGRID Bus Reactor I 400 Bongaigaon 50
POWERGRID Bus Reactor II 400 Bongaigaon 50
POWERGRID Bus Reactor III 400 Bongaigaon 80
POWERGRID Bus Reactor IV 400 Bongaigaon 80
POWERGRID Bus Reactor 132 Aizwal 20
POWERGRID Bus Reactor 132 Kumarghat 20
POWERGRID Bus Reactor I 400 Silchar 63
POWERGRID Bus Reactor II 400 Silchar 63
POWERGRID Bus Reactor 132 Ziro 20
POWERGRID Bus Reactor 132 Imphal 20
POWERGRID Bus Reactor 132 New
Mariani 20
POWERGRID Bus Reactor 400 Biswanath
Chariali 80
ASSAM Bus Reactor I 220 Mariani 12.5
ASSAM Bus Reactor II 220 Mariani 12.5
ASSAM Bus Reactor 400 Azara 63
MEGHALAYA Bus Reactor 400 Byrnihat 63
OTPC Bus Reactor 400 Palatana 80
Tertiary Reactors
POWERGRID Tertiary 33 Balipara 4X25
POWERGRID Tertiary 33 Bongaigaon 2X25
POWERGRID Tertiary 33 Misa 4X25
* Convertible to Bus reactor
Figure 2.3: Bus/Line/Tertiary Reactors of NER
CHAPTER 3: SYSTEM RESTORATION APPROACH
The following specific points must be adopted considering the importance of system restoration
3.1 General Guidelines
i) This document should be available in the Control Room of each Load Despatch Centre &
readily accessible to all system operators.
ii) Black Start and Restoration Procedure of Regional Grid under various conditions (Partial /
Total Blackout) shall be reviewed /updated by NERLDC annually in consultation with
NLDC, all Users, STU, SLDC, CTU and NERPC Secretariat. (As per Clause No 5.8(a) of
IEGC)
iii) Black Start and Restoration Procedure of each system of User’s/STU/CTU within a Region
under various conditions (Partial / Total Blackout) will be finalized by the concerned
User’s/STU/CTU in co-ordination with NERLDC. The procedure will be reviewed,
confirmed and/or revised once every year. Mock trial run of this procedure for different
sub-system shall be carried out by User’s/STU/CTU at least once in every six months
under intimation of NERLDC. Diesel Generators set for black start would be tested on
weekly basis and test report shall be sent to NERLDC on quarterly basis. (As per Clause
No 5.8(b) of IEGC)
iv) List of essential loads with categories to be prepared by User/SLDC and sent to NERLDC.
Inter State/Inter Regional links, synchronizing points and essential loads to be restored on
priority shall be available with NLDC, RLDC & SLDC. (As per Clause No 5.8(c) of IEGC)
v) NERLDC will co-ordinate entire restoration process through SLDC /ISGS /POWERGRID
etc.
vi) During restoration process, NERLDC is to be allowed to operate the Grid with reduced
security standard for voltage and frequency in order to achieve fastest possible recovery.
(As per Clause No 5.8(d) of IEGC)
vii) All communication channels required for voice communication during the restoration
process must be operational. At least one channel of voice communication is to be kept
free for NERLDC communication. (As per Clause No 5.8(e) of IEGC & As per Clause No
17 of CEA (Grid Standards) Regulation)
viii) Healthiness of communication system and ancillaries at all Load Despatch Centres, Power
Stations and Sub-Stations should be checked at least once in every week to ensure
availability of communication system during the periods of crisis.
ix) List of phone numbers(V-SAT, Landline, Mobile & ULDC) of Control Rooms of all
Load Despatch Centres, Power Stations and important Grid Sub-Stations should be
available at all Control Rooms and to be distributed to all concerned. Any change or
addition of above phone numbers should be incorporated time to time and to be
communicated to all concerned.
x) Constituents should organize one day appreciation course on power system restoration at
regional level, at least once in a year for
a. Top Management Group/Chief of Load Despatch Centres
b. Load Despatch Personnel/Power System Operators/Sub-Station Operators
xi) System Operators are expected to be thoroughly conversant with
(a) Reactive Capability of Generators
(b) Voltage Control through the following means:-
Charging the shorter line first
Switching off Capacitor Bank
Taking Bus Reactors into service
Charging Transformers and taking Bus Reactors into service
Converting Line Reactors into Bus Reactors wherever feasible.
Operating Generators at minimum Voltage levels
Changing Transformer Taps
Energisation of fewer High Voltage Lines.
(c) Network connectivity by heart and
(d) They should be able to converse fluently in Hindi/English
xii) Power Station which has Black Start capability should be tested at least once in a month.
Power Station which has DG Set should be explored for Black Start Capability.
xiii) Synchronization facility wherever available should be checked periodically and should be
kept in working condition. Periodic report of non-functioning of Synchronoscope is to be
sent to NERLDC.
xiv) All 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 non-
functioning of Disturbance Recorder/Sequential Event Recorder to be sent to NERLDC.
(As per 15.4 of CEA Grid Standards Regulation)
xv) Priority wise loads are to be secured in steps during restoration process. This is to be
documented by each User/SLDC and informed to NERLDC.
xvi) OLTC of Transformers shall be tested at least once in a week. Periodic report of non-
functioning of OLTC of Transformer to be sent to NERLDC.
3.4 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 Eastern Region is still there or not. If interconnection with
Eastern Region 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)
3.3 Important Considerations during Restoration
i) Generating Stations which have black start facilities have to start up immediately.
ii) Availability of Generation Capacity in each island / sub system to be ensured.
iii) Availability of transmission lines in the interconnection between islands / sub systems to
be ensured.
iv) Load to be added in small steps with smaller and radial loads. Larger load may be
connected after consultation with NERLDC.
v) For developing island / sub system, special care should be taken to closely 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.
vii) UFRs are to be kept deactivated as frequency excursions at this stage may be wider than
normal condition. SPS are also to be kept deactivated.
viii) A reasonable active to reactive power ratio is to be maintained so that the machine can be
operated normally.
ix) Auxiliary power to be readily available so that machine can be operated normally.
x) Total auxiliary power drawn by the sub-system to be kept within 3% of the capacity of the
source.
xi) Before synchronization between two islands there should be proper co-ordination for
frequency adjustment.
xii) Risky synchronization shall be avoided as small island may not be able to survive the jerk
xiii) While releasing loads, it is to be ascertained whether machines can supply the power.
xiv) Tap Position of Transformer, Bus Voltage and Frequency at Power Stations and Sub-
Stations should be closely monitored to ensure that over fluxing does not occur.
xv) Shift personnel should promptly formulate the strategy to be adopted in co-ordination with
NERLDC for quick restoration of the Grid.
xvi) The work of restoration in the Control Room should be shared & co-ordinated among the
shift personnel for smooth & quick restoration. Crisis Management Group to be formed,
consisting of expert personnel & called for early restoration of the system.
xvii) Shift personnel should preferably be retained till restoration is over, before handing over
the charge to the next shift.
3.4 Special Consideration in extending/availing start up power
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.
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
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
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.
3.5 Some 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.
CHAPTER 4: Broad Classification of North-
Eastern Regional Grid
Depending on the network connectivity, NER Grid is broadly classified as follows.
a) 400 / 220 kV Network of POWERGRID
b) 400 / 220 / 132 kV Network of Assam System
c) 220 / 132 kV Network of Arunachal Pradesh System
d) 400 / 220 / 132 kV of Southern part of Network comprising of Nagaland, Manipur,
South Assam, Mizoram, Tripura, Meghalaya, POWERGRID and NETC (North East
Transmission Company)
4.1 400 / 220 kV Network of POWERGRID
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 NEWS Grid through this network. The
network configuration is described as below:
a. 400/220 kV Bongaigaon (PG) Sub-Station of NER Grid is connected with 400 kV New
Siliguri (PG) Sub-Station of ER Grid through 400 kV Q/C New Siliguri – Bongaigaon
lines.
b. 220/132 kV Salakati (PG) Sub-Station of NER Grid is connected to 220 kV Birpara (PG)
Sub-Station of ER Grid through 220 kV D/C Birpara – Salakati lines. 220 kV Salakati Sub-
Station and 400 kV Bongaigaon Sub-Station are connected through 315 MVA, 400/220 kV
ICT.
c. 400/220 kV Bongaigaon (PG) Sub-Station is connected to 400/220 kV Bongaigaon
Thermal Power Station (BTPS) of NTPC through 400 kV D/C Bongaigaon – BTPS lines.
Voltage level at 400/220 kV Bongaigaon Thermal Power Station (BTPS) is steped down to
220 kV level through (2x315) MVA ICTs. 400/220 kV Bongaigaon (PG) Sub-Station is
connected to 400/220/132 kV Balipara (PG) Sub-Station through 400 kV Q/C Bongaigaon
– Balipara lines.Voltage level at 400/220/132 kV Balipara (PG) Sub-Station is steped
down to 220 kV and 132 kV level through 1x315 MVA ICT and 2x50 MVA ICTs
respectively.
d. 400 kV D/C Balipara – Misa lines and 400 kV Q/C Balipara – Biswanath Chariali lines
connect 400/220/132 kV Balipara (PG) Sub-Station with 400/ 220 kV Misa (PG) Sub-
Station and 400/132 kV Biswanath Chariali substation respectively. 400 kV Bus of Misa is
connected to 220 kV Bus through 2 x 315 MVA ICTs.
e. (1) 400/220 V Misa (PG) Sub-Station is connected with 220/132 kV Kopili (NEEPCO)
Power Station, 220/132 kV Dimapur (PG) Sub-Station through 220 kV T/C Misa – Kopili
lines, 220 kV D/C Misa – Dimapur lines respectively
(2) Also 400/220 V Misa (PG) Sub-Station is connected with 220 kV AGBPP (NEEPCO)
through 220 kV Misa-New Mariani-AGBPP S/C line and 220 kV Misa-Mariani (Assam)-
AGBPP S/C line.
(3) 400/220 kV Misa (PG) Sub-Station is also connected to 220/132 kV Samaguri
(Assam) Sub-Station through 220 kV D/C Misa – Samaguri lines.
(4) 400/220 kV Misa (PG) Sub-Station is connected with 400/220/132 kV Killing
(Byrnihat) Sub-Station of Meghalaya through 220 kV D/C Misa – Killing lines. Voltage
level of 400/220/132 kV Killing (Byrnihat) Sub-Station is step down to 220 kV and 132
kV level through (2x315) MVA and (2x160) MVA ICTs respectively.
f. Voltage level at 220/132 kV Kopili power station is steped down to 132 kV level through
(1x60 + 1 x 160) MVA ICTs. Presently 60 MVA ICT is under shutdown. Again, Voltage
level at 220/132 kV Dimapur Sub-Station is stepped down to 132 kV level through (2 x
100) MVA ICTs.
g. Voltage Level at 220/132 kV Mariani sub-staion and 220/132 kV Samguri sub-staion of
Assam are stepped down to 132 kV level through (2x100) MVA and (3x 50) MVA ICTs
respectively.
h. 400/132 kV Biswanath Chariali Sub Station is connected to 400/132 kV Ranganadi
(NEEPCO) through 400 kV D/C Biswanath Chariali-Ranganadi lines. 400 kV Bus of
Biswanath Chariali is connected to 132 kV Bus through 2 x 200 MVA ICTs.
i. 220 kV New Mariani (PG) substation is connected with 220/132 kV Mokokchung (PG)
substation through 220 kV D/C New Mariani(PG)- Mokokchung(PG) lines.220 kV bus of
220/132 kV Mokokchung(PG) substation is connected with 132 kV bus through (2 x 30 )
MVA ,220/132 kV ICTs.
4.2 400/220 / 132 kV Network of Assam System
Assam has its own 400 kV, 220 kV & 132 kV sub-stations through which Assam is connected to
the Main Grid. Connectivity of Assam system with the Grid is described as below:-
a. 220/132 kV BTPS (Assam) Sub-Station is connected with 220/132 kV Salakati (PG) Sub-
Station through 220 kV D/C BTPS – Salakati lines. Again, 220 kV Bus of BTPS is
connected to 132 Bus through (1X 80MVA + 1 X 160 MVA) ICTs.Also 400/220 kV
Bongaigaon Thermal Power Station (BTPS) is connected to 220/132 BTPS(Assam)
through (2x315) MVA , 400/220 kV ICTs.
b. 132 kV Dhaligaon, 132 kV Barnagar, 132 kV Nalbari, 132 kV Rangia, 132 kV Rowta, 132
kV Sipajhar, and 132 kV Depota Sub-Stations are connected with 220/132 kV BTPS, and
400/220/132 kV Balipara (PG) Sub-Stations through 132 kV lines. 220/132 kV Samaguri
Sub-station is connected with 400/220/132 Balipara (PG) Sub-station through 220 kV
Samaguri – Balipara S/C line.
c. 400/220 kV Azara Sub-Station is connected with 400/220 kV Bongaigaon S/S and 400/132
kV Silchar S/S through 400 kV Bongaigaon-Azara S/C line and 400 kV Silchar-Azara S/C
line respectively.
d. 220/132 kV Agia Sub-Station is connected with 220/132 BTPS Sub-Station and 132 kV
Nangalbibra Sub-Station of Meghalaya through 220 kV D/C BTPS – Agia lines and 132
kV Agia – Nangalbibra lines respectively. Voltage level at 220/132 kV Agia Sub-Station is
stepped down to 132 kV level through (1 x 100 + 1 x 50)MVA ICTs.
e. Again, 220/132 kV Agia is connected with 400/ 220 kV Azara sub-station through 220 kV
S/C Agia – Boko - Azara line and direct 220 kV Agia – Azara lines respectively. Voltage
level at 400/220 kV Azara sub-station is stepped up to 400 thorugh (2 x 315) MVA ICTs.
f. 400/220 kV Azara Sub-Station is connected with 220/132 kV Sarusajai Sub-Station
through 220 kV (D/C) Azara - Sarusajai lines.Voltage level at 220/132 kV Sarusajai Sub-
Station is stepped down to 132 kV level through (3 x 100) MVA ICTs.
g. 220/132 kV Sarusajai Sub-Station is connected with 220/132 kV Samaguri Sub-Station
through 220 kV Sarusajai – Jahawar Nagar- Samaguri and 220 kV Sarusajai – Samaguri
lines. 220/132 kV Sarusajai Sub-Station is also connected with 220 kV Langpi Power
Station through 220 kV D/C Sarusajai – Langpi lines respectively.
h. 132 kV Kahilipara Sub-Station is connected with 220/132 kV Sarusajai Sub-Station
through four numbers of 132 kV Sarusajai – Kahilipara lines & with Rangia Sub-Station
through 132 kV Kahilipara –Sishugram - Rangia & 132 kV S/C Kahilipara – Rangia lines.
i. 132 kV LTPS, 132 kV NTPS, 220/132 kV Tinsukia and 132 kV Dibrugarh Sub-Station is
connected with 220/132 kV Mariani Sub-Station and 220 kV AGBPP through 132 kV S/C
LTPS - Mariani and 220 kV D/C Tinsukia – AGBPP lines respectively.
j. 220/132 kV Mariani, 132 kV Golaghat and 132 kv Bokajan Sub-Stations are connected
with 220/132 kV Dimapur (PG) Sub-Station through 132 kV S/C Mariani – Golaghat -
Bokajan - Dimapur line.
k. 132 kV Pavoi (Biswanath Chariali) is connected with 400/132 kV Biswanath Chariali (PG)
through 132 kV D/C Biswanath Chariali(PG)-Pavoi lines.132 kV Pavoi substation is also
connected with 132 kV Gohpur substation and 132 kV Sonabil substation through 132 kV
S/C Pavoi-Gohpur line and 132 kV S/C Pavoi-Sonabil line respectively.
l. 132 kV Gohpur, 132 kV Pavoi (Bishwanath Chariali), 132 kV North Lakhimpur, 132 kV
Dhemaji and 132 kV Majuli Sub-Stations are connected with 132 kV Nirjuli (PG) Sub-
Station through 132 kV S/C Nirjuli – Gohpur line. 132 kV Gohpur, 132 kV Pavoi
(Bishwanath Chariali), 132 kV North Lakhimpur, 132 kV Dhemaji and 132 kV Majuli
Sub-Stations are also connected with 400/220/132 kV Balipara (PG) Sub-Station through
132 kV Balipara – Sonabil - Gohpur line.
m. 132 kV Sonabil substation is connected with 132 kV Depota substation, 132 kV Pavoi
substation, 132 kV Gohpur substation and 400/220/132 kV Balipara substation through
132 kV S/C Sonabil - Depota line, 132 kV S/C Sonabil –Pavoi line, 132 kV S/C Sonabil –
Gohpur line and 132 kV S/C Sonabil –Balipara line respectively.
n. 132 kV Rangia substation is also internationally connected with Bhutan system through
132 kV S/C Rangia-Deothang line.
4.3 220 / 132 kV Network of Arunachal Pradesh System
The connectivity of 220 kV & 132 kV Network of Arunachal Pradesh is as follow:-
a) 132 kV Ziro (PG), 132 kV Daporizo and 132 kV Along Sub-Stations are connected with
400/132 kV Ranganadi (NEEPCO) Power Station through 132 kV S/C Ranganadi – Ziro-
Daporizo-Along line.
b) 132 kV Nirjuli (PG) Sub-Station is connected with 400/132 kV Ranganadi (NEEPCO)
Power Station & 132 kV SMS Sub-Station of Arunachal through 132 kV S/C Ranganadi –
SMS - Nirjuli line (T Connection at SMS) and also with 132 kV Gohpur Sub-Station of
Assam through 132 kV S/C Nirjuli – Gohpur line.
c) 132 kV Itanagar Sub-Station is connected with 132 kV Nirjuli (PG) Sub-Station through
four nos. 33 kV feeders. Again, 132 kV Itanagar can draw power from 132 kV SMS Sub-
station via 132 kV Naharlagun Sub-station through 132 kV SMS – Naharlagun-Itanagar
line (Presently charged at 33 kV).
d) 132 kV Khupi, 132 kV Kimi Sub-Stations are connected with 400/220/132 kV Balipara
(PG) Sub-Station through 132 kV S/C Balipara – Khupi - Kimi line and 220/132 kV
Deomali Sub-Station is connected with 220 kV AGBPP (NEEPCO) through 220 kV S/C
AGBPP – Deomali line respectively.
4.5 400 / 220 / 132 kV Southern part of NER Grid comprising of Nagaland, Manipur,
South Assam, Mizoram, Tripura, Meghalaya, POWERGRID and NETC (North
East Transmission Company)
The connectivity of 132 kV Network comprising of Nagaland, Manipur, South Assam, Mizoram,
Tripura and Meghalaya is as follow:
Nagaland System is connected with the Main Grid through:-
a) 132 kV D/C Dimapur (PG) – Dimapur line
b) 132 kV S/C Dimapur (PG) – Kohima line
c) 132 kV S/C Karong (Manipur) – Kohima line
d) 132 kV S/C Doyang (NEEPCO) - Mokokchung line
e) 132 kV S/C Mariani (Assam) – Mokokchung line (presently under outage)
f) 66 kV S/C Dimapur – Bokajan (Assam) line
g) 132 kV D/C Mokokchung (PG)-Mokokchung(S) lines
Manipur System is connected with the Main Grid through:-
a) 132 kV D/C Imphal (PG) – Imphal lines
b) 132 kV S/C Imphal (PG) – Ningthoukhong line
c) 132 kV S/C Kohima (Nagaland) – Karong line
d) 132 kV S/C Loktak (NHPC) – Ningthoukhong line
e) 132 kV S/C Loktak (NHPC) – Rengpang line
f) 132/33 kV, 1 X 20 MVA Transformer at Jiribam (PG) Sub-Station
Mizoram System is connected with the Main Grid through:-
a) 132 kV S/C Aizawl (PG) – Zuangtui line
b) 132 kV S/C Aizawl (PG) – Laungmual line
c) 132 kV S/C Badarpur (PG) – Kolasib line (T connection of 132 kV Bairabi
substation in this line)
d) 132 kV S/C Aizawl (PG) – Kolasib line
Tripura System is connected with the Main Grid 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 (Missiontila) line
d) 132 kV S/C Palatana – Surjyamani Nagar line
e) 132 kV S/C Palatana – Udaipur line
f) 132 kV D/C Silchar - PK Bari lines
g) 132 kV S/C Monarchak(NEEPCO) – Surjyamani Nagar line
South Assam is connected with the Main Grid through:-
a) 132 kV S/C Badarpur (PG) – Panchgram line
b) 132 kV S/C Lumshnong (Meghalaya) – Panchgram line
c) 132 kV S/C Dharmanagar (Tripura) – Dullavcherra line
d) 132 kV S/C Jiribam (PG) – Pailapool line
e) 132 kV S/C Haflong (PG) – Haflong line
f) 132 kV S/C Silchar – Dullavcherra line
g) 132 kV S/C Silchar – Panchgram line
h) 132 kV D/C Silchar – Srikona lines
i) 132 kV S/C Khandong (NEEPCO) – Umrangshu line-Haflong (PG) line
Meghalaya system is connected with the Main Grid through
a) 400 kV S/C Silchar(PG)-Byrnihat line
b) 400 kV S/C Bongaigaon-Byrnihat line
c) 220 kV D/C Misa – Killing (Byrnihat) lines
d) 132 kV D/C Khliehriat(PG) – Khliehriat lines
e) 132 kV S/C Panchgram(Assam) – Lumshnong line
f) 132 kV Agia (Assam) – Nangalbibra line
g) 132 kV D/C Kahilipara(Assam) - Umtru lines
h) 132 kV D/C Sarusajai (Assam) – Umtru lines
The connectivity of the 132 kV System with 400 kV & 220 kV System & major
connectivity of intra 132 kV System:-
a. 220/132 kV Dimapur (PG) Sub-Station is connected with 400/220 kV Misa (PG)
Sub-Station through 220 kV D/C Misa – Dimapur lines. 220 kV Bus of Dimapur
(PG) Sub-Station is connected to 132 kV Bus through 2X100 MVA ICT.
b. 220/132 kV Dimapur (PG) Sub-Station is connected with 132 kV Imphal (PG) Sub-
Station through 132 kV S/C Dimapur – Imphal line.
c. 220/132 kV Dimapur (PG) Sub-Station is connected with 132 kV Doyang
(NEEPCO) substation through 132 kV D/C Dimapur(PG)-Doyang(NEEPCO) lines.
d. 132 kV Imphal (PG) Sub-Station is connected with 132 kV Loktak (NHPC) Power
Station through 132 kV S/C Imphal(PG) – Loktak line.
e. 132 kV Imphal (PG) Sub-Station is connected with 400/132 kV Silchar S/S through
132 kV D/C Silchar(PG)-Imphal(PG) lines.
f. 132 kV Loktak (NHPC) Power Station is connected with 132 kV Jiribam (PG) Sub-
Station through 132 kV S/C Loktak – Jiribam line.
g. 132 kV Jiribam (PG) Sub-Station is connected with 132 kV Haflong (PG) Sub-
Station, 132 kV Badarpur (PG) Sub-Station and 132 kV 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.
h. 132 kV Khandong (NEEPCO) Power Station is connected with 220/132 kV Kopili
(NEEPCO) Power Station through 132 kV D/C Kopili – Khandong lines. 220 kV
Bus of Kopili Power Station is connected to 132 kV Bus through 1X160 MVA ICT.
i. 132 kV Khandong (NEEPCO) Power Station is connected with 132 kV Khliehriat
(PG) Sub-Station and 132 kV Haflong (PG) Sub-Station through 132 kV D/C
Khandong – Khliehriat lines and 132 kV S/C Khandong – Haflong line respectively.
j. 132 kV Badarpur (PG) Sub-Station is connected with 132 kV Khliehriat (PG) Sub-
Station, 132 kV Kumarghat (PG) Sub-Station, 132 kV Jiribam (PG) Sub-Station and
132 kV 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.
k. Again, 132 kV Badarpur (PG) Sub-Station is connected with 400/132 kV Silchar
(PG) Sub-Station through 132 kV (D/C) Badarpur – Silchar lines.
l. 132 kV bus of Silchar Sub-Station is connected with 400 kV bus through 400 / 132
kV, 2 x 200 MVA ICT.
m. 400/132 kV Silchar Sub-Station is connected with 400/132 kV Palatana Power
station through 400 kV D/C Silchar – Palatana lines. 400 kV Bus at Palatana
Power station is connected with 132 kV Bus through 1 x 125 MVA ICT. 400/132
kV Palatana Power station is also connected with Tripura system through 132 kV
Palatana – Udaipur & 132 kV Palatana – Surjyamani Nagar lines respectively.
n. Again, 400/132 kV Silchar Sub-Station is connected with 400/220/132 kV Killing
(Byrnihat) sub-station through 400 kV S/C Silchar – Byrnihat line. 400 kV bus of
Byrnihat Sub-Station is connected to 220 kV bus through 2 x 315 MVA ICT. 220
kV bus of Byrnihat Sub-Station is connected to 132 kV bus through 2 x 160 MVA
ICT.
o. 400/132 kV Silchar Sub-Station is also connected with 400/220 kV Azara (Assam)
sub-station through 400 kV S/C Silchar – Azara line. 400 kV bus of Azara Sub-
Station is connected to 220 kV bus through 2 x 315 MVA ICT.
p. 132 kV Kumarghat (PG) Sub-Station is connected with 132 kV AGTPP
(NEEPCO) and 132 kV Aizawl (PG) Sub-Station through 132 kV S/C Kumarghat
– AGTPP line and 132 kV S/C Kumarghat – Aizawl line respectively.
4.5 (+/-) 800 kV HVDC Multi-terminal network connecting N E Region with North
Region
HVDC Biswanath Chariali (NER) – Alipurduar (ER) – Agra (NR) would be the first Muti-
terminal HVDC in India with terminal located at Biswanath Chariali (NER), Agra (NR) and
Alipurduar (ER). The capacity of each terminal at Biswanath Chariali and Alipurduar is of 3000
MW.There is two terminals at Agra with capacity of 3000 MW each.
Only Pole1 at Agra and Biswanath Chariali were commissioned in October 2015 and power flow
between ER – NER is presently taken place through Pole1.
CHAPTER5: 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 assistance from Eastern Region (ER) Grid
is available
2. Restoration of NER Grid after total collapse, when assistance from Eastern Region (ER) Grid
is not available
3. Restoration of 400 / 220 / 132 kV Southern part of Network comprising of Manipur, South
Assam, Mizoram, Tripura, part of Meghalaya , AGTPP and Palatana after partial collapse
AGTPP and Palatana after partial collapse.
NER Grid under above scenarios would 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 region or should require taking from outside the neibouring region for early
restoration. The following procedure is to be adopted for restoration of affected system:-
o Source of startup power
o Identifying the critical / essential loads of each sub-system / island
o Points of synchronization with other sub-system / island
o Action to be taken by various Generating Stations and Sub-Stations
Figure 5.1: PMU Plot after disturbance on 24/09/15
5.1 Restoration of NER Grid after total collapse, when assistance from ER Grid is
available
or restoration of NER Grid from total collapse condition, a multi-pronged restoration
strategy is envisaged in which some sub-systems and islands are to be built up
simultaneously by utilizing power from Eastern Region (ER) Grid and black start facilities
available in various Power Stations in North Eastern Region. In the restoration process
systems build up and build down strategies are adopted for quick restoration.
For restoration of NER Grid from total collapse condition, the following sub-systems /
islands are to be built up in parallel
o Sub-system 1 comprising of Arunachal Pradesh ,Central Assam and Nagaland
o Sub-system 2 comprising of Southern part of network comprising of South Assam,
part of Mizoram, part of Meghalaya & capital load of Assam
o Sub-system 3 comprising of Lower Assam and part of Meghalaya load
o Formation of Upper Assam Island comprising of Dibrugarh, Nazira andTinsukia
sub-stations
o Formation Meghalaya Island
o Formation Tripura Island with AGTPP (NEEPCO) power station comprising of
Mizoram
o Formation Loktak (NHPC) Island comprising of Manipur and part of Nagaland
5.1.1 Formation of Sub-system 1 comprising of Arunachal Pradesh, Central Assam and Nagaland
The above sub –system is formed by utilizing power from Eastern Region. Following are
the parts of network of NER Grid which would be restored through this sub -system
a. Main network comprising of following Sub-stations and Power stations :
Sub-Stations:
F
(1) 400/220 kV Bongaigaon (2) 220/132 kV Salakati (3) 132 kV Gelephu (4)
400/220/132 kV Balipara (5) 400/132 kV Biswanath Chariali (PG) (6) 132kV
Nirjuli (7) 400/220 kV Misa (8) 220/132 kV Dimapur
Power-Stations:
(1) 400/220 kV BTPS (NTPC) (2) 400/132 kV RHEP (3)220 kV AGBPP (4) 132
kV DHEP (3) 220/132 kV Kopili (4) 132 kV Khandong
b. Arunachal Pradesh comprising of 132 kV Khupi, 132 kV Kimi, 132 kV Ziro, 132 kV Lekhi
(SMS), 132 kV Itanagar and 220 kV Deomali Sub-stations.
c. Central Assam comprising of 132 kV Gohpur, 132 kV Depota, 132 kV Pavoi, 132 kV Rowta,
132 kV Sipajhar, 132 kV Dhemaji, 132 kV North Lakhimpur, 132 kV Majuli, 220/132 kV
Samaguri, 220/132 kV Mariani. 132 kV Sonabil substations.
d. Nagaland System comprising of 132 kV Dimapur, 132 kV Kohima and 132 kV Mokokchung
Sub-stations.
estoration procedures for sub-system 1:
1) Power required for this sub system shall be taken from 400 kV New Siliguri (ER) Sub-
Station to 400 kV / 200 kV Bongaigaon (NER) Sub-Station through any one of 400 kV
Q/C New Siliguri – Bongaigaon lines.
2) In case of delay in receiving power from 400 kV New Siliguri (ER) Sub-Station, then the
following procedure shall be adopted :-
220/132 kV Salakati (NER) Sub-Station shall receive power from 220 kV Birpara (ER)
Sub-Station through any one of 220 kV D/C Birpara – Salakati lines. Any one of 400 kV
Bus(s) at 400/220 kV Bongaigaon Sub-Station shall be charged through 315 MVA ICT
at 400/220 kV Bongaigaon Sub-Station. Again, 220/132 kV Salakati Sub-Station shall
charge any one of 220 / 132 kV , 50 MVA ICT & shall extend power to 132 kV Gelephu
Sub-Station through 132 kV S/C Saklakati – Gelephu line.Load at Gelephu can be
connected in co-ordination with NLDC(India) & NLDC(Bhutan). Bus Reactors at 400
kV New Siliguri Sub-Station and 400 kV Bongaigaon Sub-Station shall be taken into
R
service to contain over voltage. 400 kV Bongaigaon (PG) Sub-Station shall extend power
to 400/220/132 kV Balipara (PG) Sub-Station through any one of 400 kV Q/C Balipara –
Bongaigaon lines. Any one of 220 kV Bus(s) at 220/132 kV Salakati Sub-Station shall be
charged through 315 MVA ICT of 400/220 kV Bongaigaon Sub-Station. If required,
Tertiary Reactor at Bongaigaon may be taken into service to contain over
voltage.400/220 kV BTPS (NTPC) shall receive power from 400/220 kV Bongaigaon
sub-station.
Restoration of Arunachal Pradesh
3) 400/220/132 kV Balipara (PG) Sub-Station shall extend power to 400/220 kV Misa (PG)
Sub-Station through any one of 400 kV D/C Balipara – Misa lines and Shunt Reactors at
Balipara and Misa Sub-Stations shall be taken into service to contain over 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 over voltage. 132 kV Bus at Balipara Sub-Station shall be
charged through any one of 2X50 MVA ICTs at Balipara Sub-Station. Balipara Sub-
Station shall extend power to 132 kV Khupi & 132 kV Kimi Sub-Stations of Arunachal
through 132 kV Balipara – Khupi - Kimi lines. Load at Khupi & Kimi shall be connected
in co-ordination with SLDC, Arunachal Pradesh.
4) 400/132 kV Biswanath Chariali(PG) shall receive power through any one of 400 kV Q/C
Balipara-Biswanath Chariali lines.Bus reactor at Biswanath Chariali(PG) and Balipara
(PG) may be taken into service for containing over voltage. 132 kV Bus at Biswanath
Chariali can be charged through any one of 400/132 kV , 200 MVA ICTs at Biswanath
Chariali(PG)
5) 400/132 kV Ranganadi (NEEPCO) Power Station can receive power from 400/132 kV
Biswanath Chariali (PG) Sub-Station through any one of 400 kV D/C Biswanath Chariali
(PG)– Ranganadi lines. Line Reactor of other 400 kV ckt at Ranganadi Power Station
can be taken into service as bus reactor to contain over voltage Any one of 132 kV
Bus(s) at Ranganadi Power Station shall be charged through any one of 2X360 MVA
ICTs at Ranganadi Power Station. Ranganadi (NEEPCO) Power Station shall extend
power to 132 kV Lekhi(Arunachal Pradesh) and 132 kV Nirjuli (PG) Sub-Stations
through 132 kV S/C Ranganadi –Lekhi- Nirjuli and shall extend power to 132 kV
Daporijo and 132 kV Along (Arunachal Pradesh) Sub-Stations through 132 kV S/C
Ranganadi – Ziro - Daporijo– Along lines.. Load shall be connected at SMS, Ziro,
Daporijo and along in co-ordination with SLDC, Arunachal Pradesh.
6) 400/132 kV Ranganadi (NEEPCO) Power Station shall bring their machines if required
and synchronize with this sub-system. Otherwise, if the power received from Biswanath
Chariali(PG) 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 Lekhi, Nirjuli & Ziro
Sub-Stations and wait for extension of power from Biswanath Charilai Sub-Stations. If
possible they can also charge one circuit of 400 kV D/C Ranganadi – Biswanath Charilai
line for synchronization.7) 33 kV Bus at 132 kV 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 132 kV Itanagar (Arunachal Pradesh) Sub-Station through any one
of four nos of 33 kV feeders. 132 kV Itanagar Sub-Station can also receive power from
Lekhi Sub-Station through 132 kV Naharlagun (Arunachal Pradesh) Sub-Station. Load
shall be connected at Itanagar in co-ordination with SLDC, Arunachal Pradesh.
Restoration of Central Assam
7) (a) Balipara (PG) Sub-Station shall extend power to Depota (Assam) 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 one of 132 kV D/C Depota – Rowta line. Load at Rowta shall be
connected in co-ordination with SLDC, Assam
(b) 400/220/132 kV Balipara (PG) Sub-Station shall also extend power to 132 kV
Sonabil (Assam) Sub-Station through 132 kV S/C Balipara –Sonabil line.132 kV Sonabil
substation can also receive power from 132 kV Depota substation through 132 kV S/C
Depota-Sonabil line.132 kV shall extend power to 132 kV Pavoi subatation and 132 kV
Gohpur substation through charging of 132 kV S/C Sonabil-Pavoi line and 132 kV S/C
Sonabil - Gohpur line respectively.
(c) 132 kV Pavoi (Assam) substation can also receive power from 400/132 kV Biswanath
Charilai (PG) substation through any one of 132 kV D/C Biswanath Charilai-Pavoi lines.
(d) 132 kV Gohpur substation can also receive power from 132 kV Pavoi(Assam)
substation and 132 kV Nirjuli(PG) substation through charging of 132 kV S/C Gohpur –
Pavoi line and 132 kV S/C Nirjuli(PG)-Gohpur line respectively.
Load shall be connected at Gohpur in co-ordination with SLDC, Assam.
9) 132 kV Gohpur (Assam) Sub-Station shall extend power to 132 kV North Lakhimpur,
132 kV Dhemaji and 132 kV Majuli Sub-Stations. Loads at North Lakhimpur, Dhemaji
and Majuli shall be connected in co-ordination with SLDC, Assam.
SLDC, Assam and Arunachal Pradesh shall co-ordinate with NERLDC before
connecting loads to their systems
8) Any one of 220 kV Bus(s) at 400/220 kV Misa Sub-Station shall also be charged through
any one of 2 x 315 MVA ICT at Misa Sub-Station after receiving power from
400/220/132 kV Balipara (PG) Sub-Station. If required, bus reactor & Tertiary Reactor at
Misa may be taken into service to contain over voltage.
9) 400/220 kV Misa Sub-Station shall extend power to 220/132 kV Samaguri (Assam) Sub-
Station through any one of 220 kV D/C Misa – Samaguri lines. 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.
10) 220/132 kV Mariani (Assam) Sub-Station can receive power either from 400/220 kV
Misa Sub-Station through 220 kV S/C Misa – Mariani line or 220/132 kV Samaguri
(Assam) Sub-Station through 220 kV S/C Samaguri – Mariani line. Shunt Reactors at
Mariani Sub-Station shall be taken into service to contain over voltage. Load at Mariani
shall be connected in co-ordination with SLDC, Assam.
11) 220/132 kV Kopili (NEEPCO) Power Station shall receive power from 400/220 kV 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.
12) 220/132 kV Mariani Sub-Station shall extend power to 220 kV AGBPP (NEEPCO)
through 220 kV S/C Mariani – AGBPP line. 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 220kV 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.
13) 132 kV Bus at Kopili Power Station shall be charged through 160 MVA ICT at Kopili
Power Station.
14) 220/132 kV Kopili Power Station shall extend power to 132 kV 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 startup power from this sub-
system and synchronize the machines with this sub-system. Otherwise, if the extension
of power from Kopili Power Station is delayed, Khandong Power Station shall black start
one of three units and shall charge 132 kV Bus and extend power to 132 kV Haflong &
132 kV Khliehriat Sub-Stations and wait for extension of power from Kopili Power
Station. If possible, they can also charge one circuit of 132 kV D/C Kopili – Khandong
lines for synchronization
Restoration of Nagaland
15) 440/220 kV Misa (PG) Sub-Station shall extend power to 220/132 kV 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.
16) 220/132 kV Dimapur (PG) Sub-Station shall extend power to 132 kV Dimapur
(Nagaland) Sub-Station through any one of 132 kV D/C Dimapur – Dimapur line. Load
at Dimapur shall be connected in co-ordination with SLDC, Nagaland.
17) 220/132 kV Dimapur (PG) Sub-station shall extend power to 132 kV Kohima Sub-
Station through 132 kV S/C Dimapur – Kohima line. Load at Kohima shall be connected
in co-ordination with SLDC, Nagaland.
18) 132 kV Kohima Sub-station shall extend power to 132 kV Meluri Sub-Station through
132 kV S/C Kohima – Meluri line. Load at Meluri shall be connected in co-ordination
with SLDC, Nagaland.
19) 132 kV Meluri Sub-Station shall extend power to 132/66 kV Khiphire Sub-Station
through 132 kV S/C Meluri – Khiphire line. Load at Khiphire shall be connected in co-
ordination with SLDC, Nagaland.
20) 66 kV Bus at Khiphire Sub-Station shall be charged through any one of 3X6.5 MVA ICT
at Khiphire Sub-Station.
21) 132/66 kV Khiphire Sub-Station shall extend power to 66 kV Likhimro Power Station
through 66 kV Khiphire – Likhimro line.
22) 220/132 kV Dimapur (PG) Sub-Station shall also extend power to 132 kV 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 220/132 kV 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.
23) 132 kV Doyang (NEEPCO) Power Station shall extend power to 132 kV Mokokchung
Sub-Station through 132 kV S/C Doyang – Mokukchung line. Load at Mokokchung shall
be connected in co-ordination with SLDC, Nagaland.
24) This sub-system may also be synchronized with Island E at 220/132 kV Dimapur (PG)
sub-station through 132 kV S/C Dimapur – Imphal line.
25) 220/132 kV Dimapur (PG) Sub-Station can also receive power from 220/132 kV Mariani
Sub-Station through 132 kV S/C Mariani – Golaghat – Bokajan - Dimapur line.
26) 132 KV Mokokchung Sub-Station can also receive power from 220/132 kV Mariani
Sub-Station through 132 kV S/C Mariani – Mokokchung line. Presently 132 kV S/C
27) Mariani – Mokokchung line is under long outage. Early restoration of this line will help
to extend power to Mokokchung.
Note: SLDC, Assam and Nagaland shall co-ordinate with NERLDC before connecting
loads to their system
5.1.2 Formation of Sub-system 2 comprising of Southern part of network comprising of South
Assam, part of Mizoram, part of Meghalaya & capital load of Assam
The above sub –system is formed by utilizing power from Eastern Region. Following are the
parts of network of NER Grid which would be restored through this sub –system
a. Main network comprising of following Sub-stations and Power stations:
Sub Stations:
(1) 400/ 220 kV Azara (AEGCL) (2) 400/220/132kV Byrnihat (MeECL) (3) 132 kV
Khliehriat (PG) (4) 132 kV Badarpur (5) 132 kV Haflong (6) 400/132 kV Silchar
Power Stations
Palatana
b. South Assam comprising of 132 kV Panchgram, 132 kV Dullavcherra, 132 kV Srikona
and 132 kV Pailapool Sub-stations comprising of following Sub-stations and Power
stations
c. Capital load of Assam comprising of 220/132 kV Sarusasjai Sub-station & 132 kV
Kahipara Sub-station
d. Part of Meghalaya system comprising of 400/220/132 kV Byrnihat Sub-station
e. Part of Mizoram system comprising Kolasib Sub-station and Bairabi power station
estoration procedures for sub-system 2:
1) 400 kV Bongaigaon sub station shall extend power to Azara sub station and Byrnihat sub
station through 400 kV Bongaigaon – Azara and 400 kV Bongaigaon – Byrnihat lines
respectively whenever voltage comes under permissible limits after taking all reactors
in to service at Bongaigaon sub station.
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2) 220 kV bus of Azara shall be charged through one of 2 x 315 MVA ICT. Bus reactor (63
MVAr) shall be takeninto service to contain voltage.
Restoration of Capital Load of Assam
3) Azara shall extend power to Sarusajai through one of 220 kV Azara – Sarusajai line. 132
kV Bus of Sarusajai shall be charged through any one of 3 X 100 MVA ICT. Load at
Sarusajai shall be connected by SLDC Assam in consultation with NERLDC.
4) Sarusajai shall extend power to Kahilipara through four nos of 132 kV Sarusajai –
Kahilipara lines.SLDC Assam shall restore capital load of Assam at the earliest.
Restoration of part of Meghalaya load
5) 220 kV bus of Byrnihat shall be charged through any one of 2 x 315 MVA ICT. Bus
reactor (63 MVAr) shall be takeninto service to contain voltage. 132 kV bus of Byrnihat
shall be charged through one of 2 x 160 MVA ICT. Load at Byrnihat shall be restored by
SLDC, Meghalaya in consultation with NERLDC.
Restoration of South Assam load
i) Power shall be extended to 400 kV Silchar sub-station through either 400 kV S/C
Byrnihat – Silchar line or 400 kV S/C Azara - Silchar line depending on existing bus
voltage. Bus reactors at Silchar shall be taken in to service to contain voltage.
ii) 132 kV bus of Silchar shall be charge through any one of 2 x200 MVA ICT.
iii) Power shall be extended to Panchgram, Srikona and Badarpur (PG) through 132 kV
Silchar – Panchgram line, 132 kV D/C Silchar – Srikona lines and 132 kV D/C Silchar –
Badarpur lines respactively. Load at Panchgram and Srikona shall be restored by SLDC,
Assm in consultation with NERLDC.
Restoration of part of Mizoram load
iv) Power shall be extended to Kolasib through 132 kV Badarpur – Kolasib line. Load at
Kolasib restored by SLDC, Mizoram in consultation with NERLDC.
v) Kolasib shall extend power to Bairabi power station through 132 kV Kolasib – Bairabi
line.
5.1.3 Formation of Sub-system 3 comprising of comprising of Lower Assam and part of
Meghalaya load
The above sub –system is formed by utilizing power from Eastern Region. This sub system
mainly comprises of Lower Assam system consisting of following sub stations
i) 220/132 kV BTPS sub station
ii) 220/132 kV Agia sub station
iii) 220/132 kV Boko sub station
iv) 132 kV Dhaligaon sub station
v) 132 kV Barnagar sub station
vi) 132 kV Nalbari sub station
vii) 132 kV Rangia sub station
viii) 132 kV Motonga sub station of Bhutan and
ix) 132 kV Nangalbibra sub station of Meghalaya
estoration procedures for sub-system 3:
1) 220/132 kV Salakati (PG) Sub-Station shall extend power to 220/132 kV BTPS (Assam)
Sub-Station through any one of 220 kV D/C Salakati – BTPS lines.
2) 220/132 kV BTPS Sub-Station shall extend power to 220/132 kV Agia (Assam) Sub-
Station through 220 kV (D/C) BTPS – Agia line. Load at Agia shall be connected by
SLDC, Assam in co-ordination with NERLDC.
3) 132 kV bus at Agia shall be charged through any one of (1x50 + 1x100) MVA ICT.
Power shall be extended to Nangalbibra of Meghalaya through 132 kV Agia-
Nangalbibra line. Load at Nangalbibra shall be connected by SLDC, Meghalaya in
consultation with NERLDC.
4) 132 kV Bus at BTPS Sub-Station shall be charged through any one of 1X80+1X160
MVA ICT at BTPS Sub-Station. BTPS Sub-Station shall extend power to 132 kV
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Dhaligaon (Assam) Sub-Station through any one of 132 kV D/C BTPS – Dhaligaon
lines. Load at Dhaligaon shall be connected by SLDC, Assam in co-ordination with
NERLDC.
5) 132 kV Dhaligaon Sub-Station shall extend power to 132 kV Rangia (Assam) Sub-Station,
132 kV Nalbari (Assam) sub-station and 132 kV Barnagar (Assam) Sub-Station through
132 kV Dhaligaon – Barnagar –Rangia line and 132 kV Dhaligaon –Nalbari - Rangia lines.
Load at Nalbari, Rangia and Barnagar shall be connected in connected by SLDC, Assam
in co-ordination with NERLDC.
6) Again, 132 kV Rangia shall extend power to 132 kV Motonga (Bhutan) through 132 kV
Rangia – Motonga line. 132 kV Gelephu sub-station can also receive power through
Motonga. Power shall be extend to Bhutan in consultanation with NLDC and NERLDC.
7) 132 kV Rangia Sub-Station shall extend power 132 kV Sisugram (Assam) Sub-Station
through 132 kV S/C Rangia – Sishugram line. Load at Sishugram shall be connected in
co-ordination with SLDC, Assam. If required, Rangia Sub-Station shall extend power to
132 kV Rowta Sub-Station too through 132 kV Rangia – Sipajhar - Rowta & 132 kV
Rangia – Rowta line. Load at Sipajhar & Rowta may be connected in co-ordination with
SLDC, Assam.
8) 220/132 kV Agia (Assam) Sub-Station shall extend power to 220/132 kV Boko (Assam)
Sub-Station and 400/220 kV Azara Sub-Station through 220 kV S/C Agia – Boko line
and 220 kV Agia – Azara lines respectively. Boko Sub-Station shall extend power to
Azara through 220 kV Boko – Azara line. Load at Boko shall be connected by SLDC,
Assam in co-ordination with NERLDC.
9) 132 kV Kahilipara Sub-Station can also receive power from 132 kV Rangia and 132 kV
Sisugram Sub-Stations through 132 kV S/C Rangia – Kahilipara line and 132 kV S/C
Sisugram – Kahilipara line respectively.
10) 220/132 kV Sarusajai Sub-Station can also receive power from 220/132 kV Samaguri
Sub-Station of sub-system #1 through 220 kV Sarusajai – Samaguri –II.
5.1.4 Formation of Upper Assam Island comprising of Dibrugarh, Nazira and Tinsukia sub-
stations
This Island comprising of Upper Assam sytem which consist of following Sub stations and
Power stations:
Sub Stations:
(a) 132 kV Dibrugarh
(b) 132 kV Nazira
(c) 220/132 kV Tinsukia
(d) 132 kV Jorhat
(e) 132 kV Golaghat
(f) 220/132 kV Mariani
Power-stations: 132 kV NTPS and 132 kV LTPS;
The Island is formed by availing black start power from NTPS power-station
estoration procedures for Upper Assam Island:
1) 132/66 kV 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) 132 kV Bus at NTPS shall be charged through any one of 2X25 MVA ICT at NTPS.
3) 132 kV NTPS shall extend power to 132 kV LTPS (Assam) through any one of 132 kV
D/C LTPS – NTPS lines. LTPS shall bring generation and synchronize.
4) NTPS shall extend power to 220/132/66kV Tinsukia & 132/66 kV 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.
5) NTPS shall also extend power to 220/132/66 kV Tinsukia (Assam) Sub-Station through
132 kV S/C NTPS -Tinsukia line. 220/132/66 kV Tinsukia substation shall extend power
to 132 kV Dibrugarh (Assam) Sub-Station through 132 kV S/C Tinsukia – Dibrugarh
line. Load at Dibrugarh shall be connected in co-ordination with SLDC Assam. 132 kV
LTPS – Nazira line shall be closed.
6) This island shall be synchronized with sub-system 1 at 220/132V Mariani (Assam) through
132 kV S/C LTPS – Mariani line.
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5.1.5 Formation Meghalaya Island
This Island comprising of Meghalaya sytem which consist of following Sub stations and
Power stations:
Sub Stations:
(a) 132 kV Mawlai
(b) 132 kV Nehu
(c) 132 kV Khliehriat
(d) 132 kV Lumsnong
(e) 132 kV NEIGRIHMS
(f) 132 kV Umium
Power-stations:
(a) 132 kV Umium Stage 1
(b) 132 kV Umium Stage 2
(c) 132 kV Umium Stage 3
(d) 132 kV Umium Stage 4
(e) 132 kV Umtru
(f) 132 kV Leshka
The Island is formed by availing black start power from Umium Stage 1 power-station
estoration procedures for Meghalaya Island:
1) 132 kV Umiam Stg- I Power Station shall black-start and charge 132 kV Bus at Umiam
Stg- I Power Station. 132 kV Umiam Stg- III Power Station shall also black start and
charge 132 kV Bus at Umiam Stg- III Power Station.
2) 132 kV Umiam Stg I Power Station shall synchronize with Umiam Stg III Power Station
at Umium Stg III Power Station through any one of 132 kV D/C Umiam Stg I – Umiam
Stg III lines. Umiam Stg I & III Power Stations shall bring and synchronize other
machines. Load at Umiam Stg III shall be connected in co-ordination with SLDC
Meghalaya.
3) 132 kV Umiam Stg I Power Station shall extend power to 132 kV Umiam Stg II Power
Station through 132 kV S/C Umiam Stg I – Umiam II line for survival/auxiliary power.
Umiam Stg II Power Station shall bring generation if required and synchronize.
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4) 132 kV Umiam Stg III Power Station shall extend power to 132 kV Umiam Stg IV
Power Station through any one of 132 kV D/C Umiam Stg III – Umiam IV line for
survival/auxiliary power. Umiam Stg IV Power Station shall bring generation if required
and synchronize.
5) 132 kV Umiam Stg III Power Station shall extend power to 132 kV Umtru Power Station
through any one of 132 kV D/C Umiam Stg 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) 132 kV Umiam Stg I Power Station shall extend power to 132 kV Mawlai and NEHU
Sub-Stations through 132 kV S/C Umiam Stg I – Mawlai line and 132 kV S/C Umiam
Stg I – Umiam - NEHU line respectively. Load at Mawlai, Umiam and NEHU shall be
connected in co-ordination with SLDC Meghalaya.
7) 132 kV NEHU Sub-Station shall extend power to Khliehriat Sub-Station through 132 kV
S/C NEHU – NEIGRIHMS - Khliehriat line or 132 kV NEHU – Khliehriat line. Load at
Khliehriat and NEIGRIHMS shall be connected in co-ordination with SLDC Meghalaya.
8) 132 kV Khliehriat Sub-Station shall extend power to 132 kV Lumsnong Sub-Station
through 132 kV S/C Khliehriat- Lumsnong line.Load at Lumsnong shall be connected in
co-ordination with SLDC Meghalaya.
9) Again, Power shall be extended to 132 kV Leshka power station from 132 kV Khliehriat
(Meghalaya) Sub-Station through 132 kV D/C Khliehriat – Leshka lines.
10) This island shall be synchronized with sub-system 3 at 220/132 kV Sarusajai (Assam)
Sub-Station and Kahilipara (Assam) Sub-Station through any one of 132 kV D/C Umtru
– Sarusajai lines or through any one of 132 kV D/C Umtru – Kahilipara lines.
11) This island shall be synchronized with sub-system 2 at 132 kV Khliehriat (PG) Sub-
Station through any one of 132 kV D/C Khliehriat – Khliehriat lines Note:
5.1.6 Formation Tripura Island with AGTPP (NEEPCO) power station comprising of
Mizoram
This Island comprising of Tripura sytem with AGTPP (NEEPCO) power station and
Mizoram which consist of following Sub stations and Power stations:
Sub Stations:
(a) 132 kV Agartala (Tripura)
(b) 132 kV Udaipur (Tripura)
(c) 132 kV Surjyamani Nagar (Tripura)
(d) 132 kV P K Bari (Tripura)
(e) 132 kV Dhalabil (Tripura)
(f) 132 kV Zungtui (Mizoram)
(g) 132 kV Longmol (Mizoram)
Power-stations:
(a) 132 kV AGTPP (NEEPCO)
(b) 132 kV Rokhia (Tripura)
(c) 132 kV Baramura (Tripura)
(d) 400/132 kV Palatana (OTPCL)
The Island is formed by availing black start power from AGTPP power-station and Rokhia
power station
estoration procedures for Tripura Island with AGTPP (NEEPCO) power station comprising
of Mizoram:
Restoration of Tripura system
1) 132/66 kV Rokhia 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 132 kV 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.
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4) 132 kV AGTPP (NEEPCO) shall black start one of its unit and charge 132 kV Bus at
AGTPP. AGTPP shall synchronize Tripura System through any one of 132 kV D/C AGTPP
– Agartala lines. AGTPP shall bring and synchronize other machines.
5) 132 kV Agartala Sub-Station shall extend power to 132 kV 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) 132 kV Budhjangnagar shall extend power to Surjyamani Nagar through 132 kV
Budhjangnagar - Surjyamani Nagar line.Surjyamani Nagar shall extend power to 400/132
kV Palatana Power station through 132 kV Surjyamani Nagar – Palatana line.
7) 132/66 kV Rokhia Power Station shall extend power to 132 kV Udaipur Sub-Station
through 132 kV S/C Rokhia – Udaipur line. Udaipur shall extend power to Palatana through
132 kV Udaipur – Palatana line.
8) Palatana shall charge 400 kV bus through 1x125 MVA ICT and shall take start up power to
start its unit.
9) 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.
10) 132/66 kV Udaipur Sub-Station shall extend power to 132 kV Gumti Power Station through
66 kV S/C Udaipur – Gumti line.
11) Gumti Power Station shall bring generation if required and synchronize with this Island.
12) 132 kV Agartala Sub-Station shall extend power to 132 kV Dhalabil Sub-Station through
132 kV S/C Agartala – Dhalabil line. Load at Dhalabil shall be connected in co-ordination
with SLDC, Tripura.
13) 132 kV Dhalabil Sub-Station shall extend power to 132 kV Kamalpur Sub-Station through
132 kV S/C Dhalabil –Kamalpur line. Load at Kamalpur shall be connected in co-
ordination with SLDC, Tripura.
14) 132 kV Kamalpur Sub-Station shall extend power to 132 kV 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-
ordination with SLDC, Tripura.
15) 132 kV P K Bari Sub-Station shall extend power to 132 kV 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.
16) 132 kV 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 power station. Load at Dullavcherra shall be connected in co-ordination
with SLDC, Assam.
17) 132 kV P K Bari Sub-Station shall extend power to 132 kV Kumarghat Sub-Station through
132 kV S/C P K Bari – Kumarghat line.
18) 132 kV P.K.Bari Sub-Station shall extend power to 132 kV 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.
Restoration of Mizoram system
19) 132 kV AGTPP shall extend power to Kumarghat Sub-Station through 132 kV S/C AGTPP
– Kumarghat line.
20) 132 kV Kumarghat Sub-Station shall extend power to 132 kV Aizawl Sub-Station through
132 kV S/C Kumarghat – Aizawl line.
21) 132 kV Aizawl (PG) Sub-Station shall extend power to 132 kV Zuangtui & 132 kV
Luangmual Sub-Station through 132 kV S/C Aizawl – Zuangtui & 132 kV Aizawl –
Luangmual lines. Load at Zuangtui & Luangmual shall be connected by SLDC,Mizoram in
co-ordination with NERLDC.
22) If required, Bus Reactors at Kumarghat and Aizawl Sub-Stations shall be taken into service
to contain over voltage.
23) This island may be synchronized with sub-system 2 at 132 kV Badarpur (PG) Sub-Station
through 132 kV S/C Kumarghat - Badarpur line or at 400/132 kV Silchar (PG) substation
through any one of 132 kV D/C PK Bari-Silchar lines.This island may also be synchronized
with sub-system 2 at 400/132 kV Silchar (PG) Sub-Station through 132 kV S/C Dullavchera
– Silchar line.
24) This island shall be synchronized with Loktak Island (5.1.7) at 132 kV Aizwal (PG) Sub-
Station through 132 kV S/C Jiribam – Aizwal line.
Note: SLDC, Tripura and Mizoram shall co-ordinate with NERLDC before connecting loads.
5.1.7 Loktak (NHPC) Island comprising of Manipur and part of Nagaland
This Island comprising of Loktak (NHPC) power station with Manipur and part of Nagaland
which consist of following Sub stations and Power stations:
Sub Stations:
(a) 132 kV Ninthoukhang (Manipur)
(b) 132 kV Churachandpu (Manipur)
(c) 132 kV Imphal (Manipur)
(d) 132 kV Imphal (PG)
(e) 132 kV Karong (Manipur)
(f) 132 kV Kohima (Nagaland)
Power-stations:
(a) 132 kV Loktak (NHPC)
The Island is formed by availing black start power from Loktak power-station.
estoration of Loktak (NHPC) Island comprising of Manipur and part of Nagaland
1) 132 kV Loktak (NHPC) Power Station shall black start and charge 132 kV Bus.
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2) 132 kV Loktak Power Station shall extend power to 132 kV Imphal (PG) Sub-Station and
132 kV Ningthoukong Sub-Station through 132 kV S/C Loktak – Imphal and 132 kV S/C
Loktak – Ninghthoukong lines respectively. Load at Ningthoukong shall be connected by
SLDC, Manipur in co-ordination with NERLDC. Loktak Power Station shall bring and
synchronize other machines.
3) 132 kV Imphal (PG) Sub-Station shall extend power to Imphal (Manipur) Sub-Station
through any one of 132 kV D/C Imphal – Imphal lines. Load at Imphal (Manipur) shall be
connected by SLDC, Manipur in co-ordination with NERLDC.
4) Ningthoukong Sub-Station shall extend power to 132 kV Churachandpur Sub-Station
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 (PG)
line shall be closed.
5) 132 kV Imphal (Manipur) Sub-Station shall extend power to 132 kV Karong Sub-Station
and Yangangpokpi (Manipur) Sub-Station through 132 kV S/C Imphal – Karong line and
132 kV S/C Imphal – Yangangpokpi lines. Load at Karong and Yangangpokpi shall be
connected by SLDC, Manipur in co-ordination with NERLDC.
6) 132 kV Karong Sub-Station shall extend power to 132 kV Kohima Sub-Station of
Nagaland through 132 kV Karong – Kohima line. Load Komima shall be connected by
SLDC, Nagaland in co-ordination with NERLDC.
7) Loktak Power Station shall extend power to 132 kV Jiribam (PG) and 132 kV Rengpang
(Manipur) Sub-Stations through 132 kV S/C Loktak – Jiribam and 132 kV S/C Loktak –
Rengpang lines respectively. Load at Rengpang shall be connected by SLDC, Manipur in
co-ordination with NERLDC.
8) If required, 132 kV Jiribam (PG) Sub-Station shall extend power to 132 kV 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 startup power to be extended to
Baskandi Power Station for bringing their machines.
9) 33 kV Bus at Jiribam (PG) Sub-Station shall be charged through 1X20 MVA ICT at Jiribam
(PG) Sub-Station. Load at Jiribam shall be connected by SLDC, Manipur in co-ordination
with NERLDC.
10) This island shall be synchronized with sub-system 1 at 132 kV Haflong (PG) Sub-station
through 132 kV S/C Haflong – Jiribam line.
11) This island shall be synchronized with sub-system 1 either at 132 kV Imphal (PG) or
220/132 kV Dimapur (PG) Sub-Station through 132 kV S/C Dimapur - Imphal line.
12) This island shall be synchronized with sub-system 2 at 132 kV Badarpur (PG) Sub-station
through 132 kV S/C Badarpur – Jiribam line.
13) This island shall be synchronized with sub-system 2 at 400/132 kV Silchar (PG) Sub-station
through charging of any one of 132 kV D/C Silchar-Imphal(PG) lines.
Note: SLDC, Manipur shall co-ordinate with NERLDC before connecting loads.
5.1.8 Situational Awareness during the process of restoration of Grid after collapse
The above procedures laid down the process of restoration of NER Grid after total collapsed with
the help of taking start up power from neibouring Eastern Region as well as utilizing black start
facilities valaibale within the region. Several possible ways may be thought during the process of
restoration.The best methods are laid down in this document and should be followed in process of
restoration as instructed by NERLDC in real time for quick restoration of NER grid. All the sub
suystems and the Islands shall be restored simultaneously. The opeartors who are restoring the
system should be conversant enough about the Grid as well as could be capable of hadling any
kind of adverse situation confronted during the process of restoration. Following are some adverse
situations which operators may encounter during the restoaration process. The remedial measures
for this situation are also given below:
(a) Sub system 2 could not be restored due to voltage problem
It is possible that due to inadequate MVAr absoption 400 kV Bongaigan – Azara and 400
kV Bongaigan – Bynnihat lines may not the taken in to service. In that case to restore
Capital load of Assam, Byrnihat load of Meghalaya and southern part of NER Grid along
with south Assam, following process may be adopted to restore the load.
(1) Restoration of capital load of Assam:
i) 220 kV Agia sub station extend power to Sarusajai through 220 kV Agia – Sarusajai
line. 132 kV Bus of Sarusajai shall be charged through any one of 3 X 100 MVA ICT.
Load at Sarusajai shall be connected by SLDC Assam in consultation with NERLDC.
ii) Sarusajai shall extend power to Kahilipara through four nos of 132 kV Sarusajai –
Kahilipara lines.SLDC Assam shall restore capital load of Assam at the earliest
(2) Restoration of Bynihat Load load of Meghalay:
400/220 kV Misa Sub-Station shall extend power to 400/220/132 kV Byrnihat
(Meghalaya) Sub-Station through any one of 220 kV D/C Misa – Killing (Byrnihat)
lines. 132 kV Bus at Byrnihat Sub-Station shall be charged through any one of 2X160
MVA ICT. Byrnihat Sub-Station shall extend power to 132 kV EPIP II Sub-Station
through any one of 132 kV D/C Byrnihat – EPIP II lines. Load at EPIP II may be
catered to in co-ordination with SLDC, Meghalaya. 132 kV EPIP II Sub-Station shall
extend power to 132 kV EPIP I Sub-Station through any one of 132 kV D/C EPIP II –
EPIP I lines. Load at EPIP I may be connected in co-ordination with SLDC,
Meghalaya and power shall be extended progressively to Meghalaya power stations
for synchronization of machines. The related segregated operations will be carried out
in close coordination with NERLDC.
(3) Restoration of Southern part of Grid along with south Assam load:
i) 132 kV Khandong Power Station shall extend power to 132 kV Khliehriat (PG) and
132 kV Haflong (PG) Sub-Stations through any one of 132 kV D/C of Khandong –
Khliehriat lines and 132 kV S/C Khandong – Umrangshoo-Haflong line respectively.
ii) 132 kV Khliehriat (PG) Power Station shall extend power to 132 kV Badarpur (PG)
Sub-Station through 132 kV S/C Khliehriat- Badarpur line.
iii) 132 kV Badarpur Sub-Station shall extend power to 132 kV Panchgram (Assam) Sub-
Station through 132 kV S/C Badarpur – Panchgram line. 132 kV Panchgram Sub-
station shall also receive power from 400/132 kV Silchar through 132 kV Silchar –
Panchgram line.
iv) 132 kV Panchgram Sub-Station shall extend power to 132 kV Srikona Sub-Station
through 132 kV Panchgram – Srikona line.132 kV Srikona sub-station can also
receive power from 132 kV D/C Silchar-Srikona lines.
v) 132 kV Srikona shall extend power to 132 kV Pailapool Sub-Station through 132 kV
S/C Srikona – Pailapool line.
Load at Panchgram, Srikona and Pailapool shall be connected in co-ordination with
SLDC, Assam.
vi) Again, 132 kV Badarpur Sub-Station shall extend power to 400/132 kV Silchar Sub-
Station through any one of 132 kV D/C Badarpur – Silchar lines.
vii) Silchar shall charge any one of 400 kV bus through any one of 400 / 132 kV 2 x200
MVA ICT. All the shunt reactors at Silchar sub-station shall be put into service to
contain over voltage.
viii) 400/132 kV Silchar Sub-Station shall extend power to 400/132 kV Palatana Power
station through any one of 400 kV D/C Silchar – Palatana Lines, if voltage permits.
Before this, Palatana shall take start up power through any one of 132 kV Udaipur –
Palatana and 132 kV Surjyamani Nagar - Palatana of Tripura system (Island D) and
shall synchronise its unit.
ix) 132 kV Badarpur Sub-Station shall extend power to 132 kV Kolasib (Mizoram) Sub-
Station through 132 kV S/C Badarpur – Kolasib line. Load at Kolasib shall be
connected by SLDC, Mizoram in co-ordination with NERLDC.
x) 132 kV Kolasib Sub-Station shall extend power to 66 kV Bairabi (Mizoram) Power
Station for survival/auxiliary power through 66 kV Kolasib – Bairabi line.
xi) 132 kV Haflong (PG) Sub-Station shall extend power to 132 KV Haflong (Assam)
Sub-Station through 132 kV S/C Haflong – Haflong line. Load at Haflong shall be
connected in co-ordination with SLDC, Assam.
(b) Meghalaya Island could be restored due to problem in Black start
problem in machines
In case the Meghalaya Island could not be formed due to problem in black start facilities of
their machines then following process may be adopted for restoration of Meghalaya System
i) 220/132 kV Sarusajai Substation of Assam shall extend power to 132 kV Umtru
power station of Meghalaya thorugh any one of 132 kV D/C Sarusajai - Umtru lines.
ii) 132 kV Umtru shall shall extend power to 132 kV Umium stage 3 & 132 kV Umium
stage 4 power stations which shall further extended to rest part of Meghalaya system.
Machines of these power stations shall be synchronized.
(c) Latency in restoration of Tripura Island, Loktak Island and Upper Assam
Island
Some times it is observed that due to problem developed in black start facilities formation
of above Islans getting delayed or could not possible at all in that case following peocess
shall be adopted for extension of power from external source:
(1) Extension of power to Tripura Island
i) 400/132 kV D/C Silchar sub station shall extend power to P K Bari of Tripura
through any one of 132 kV Silchar – P K Bari lines.
ii) 132 kV Dullavcherra sub station of Assam shall extend power to Missiontilla of
Tripura through 132 kV Dullavcherra – Missiontilla line.
iii) 132 kV Kumarghat (PG) sub station can receive power from 132 kV Badarpur
(PG) sub station through 132 kV Badarpur – Kumarghat line.
iv) 132 kV Kumarghat (PG) sub station shall extend power to AGTPP (NEEPCO)
power station through 132 kV Kumarghat – AGTPP line.
v) 132 kV Aizawl (PG) sub station can receive power from 132 kV Kolasib sub
station through 132 kV Kolasib – Aizawl line.
(2) Extension of power to Loktak Island
i) 400/132 kV D/C Silchar sub station shall extend power to Imphal (PG) through
any one of 132 kV Silchar – Imphal lines.
ii) 132 kV Imphal (PG) shall extend power to Imphal sub station of Manipur
through any one of 132 kV D/C Imphal – Imphal lines.
iii) 132 kV Imphal (PG) shall extend power to Loktak power station through 132
kV Imphal – Loktak line.
(3) Extension of power to Loktak Island
i) 220/132 kV Mariani sub station of Assam shall receive power from 400/220 kV
Misa (PG) sub station through 220 kV Misa – Mariani line.
ii) 220/132 kV Mariani sub station of Assam shall receive power from 220/132 kV
Dimapur (PG) sub station through 132 kV Diampur – Bokajan - Golaghat –
Mariani line.
System Opeartors should tackle the other unforseen situation like circuit breaker promlem,
Isolator problem etc. which may develop during the process of restoration. System operator
shall handle the situation with highest level of intelligence and presence of mind.The main
objective should be the fastest restoration of the system with minimum time. All lines which
are yet to be restored shall be taken into service at the earliest. Load shall be released slowly
in consultion with respective SLDCs.
5.2 Restoration of NER Grid after total collapse, when assistance from ER Grid is
not available
or restoration of NER Grid from total collapsed condition, when assistance from Eastern
region is not available, the following Islands are to be built up simultaneously, by utilizing
available Black start facilities.
o Formation Tripura Island with AGTPP (NEEPCO) power station comprising of
Mizoram and South Assam
o Formation Loktak (NHPC) Island comprising of Manipur and Nagaland
o Formation of Upper Assam Island comprising of Dibrugarh, Nazira andTinsukia
sub-stations
o Formation Meghalaya Island with capital load of Assam
5.2.1 Formation Tripura Island with AGTPP (NEEPCO) power station comprising of
Mizoram and South Assam
This Island comprising of Tripura sytem with AGTPP (NEEPCO) power station, Mizoram
and south Assam which consist of following Sub stations and Power stations:
Sub Stations:
(a) 132 kV Agartala (Tripura)
(b) 132 kV Udaipur (Tripura)
(c) 132 kV Surjyamani Nagar
(Tripura)
(d) 132 kV P K Bari (Tripura)
(e) 132 kV Dhalabil (Tripura)
(f) 132 kV Zungtui (Mizoram)
(g) 132 kV Longmol (Mizoram)
(h) 132 kV Dullavcherra (Assam)
(i) 132 kV Panchgram (Assam)
(j) 132 kV Badarpur (PG)
(k) 132 kV Silchar (PG)
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Power-stations:
(a) 132 kV AGTPP (NEEPCO)
(b) 132 kV Rokhia (Tripura)
(c) 132 kV Baramura (Tripura)
The Island is formed by availing black start power from AGTPP power-station and Rokhia
power station
estoration procedures for Tripura Island :
Restoration of Tripura system
1) 132/66 kV 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 132 kV 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) 132 kV AGTPP (NEEPCO) shall also black start one of its unit and charge 132 kV Bus
at AGTPP and shall synchronize Tripura System through any one of 132 kV D/C
AGTPP – Agartala lines. AGTPP shall bring and synchronize other machines.
5) 132 kV Agartala Sub-Station shall extend power to 132/66 kV 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) 132 kV Budhjangnagar shall extend power to Surjyamani Nagar through 132 kV
Budhjangnagar - Surjyamani Nagar line.Then Surjyamani Nagar shall extend power to
400/132 kV Palatana through 132 kV Surjyamani Nagar – Palatana line.
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7) Rokhia Power Station shall extend power to 132/66 kV Udaipur Sub-Station through 132
kV S/C Rokhia – Udaipur line. Udaipur shall extend power to Palatana through 132 kV
Udaipur – Palatana line.
8) Palatana shall charge 400 kV bus through 1 x 125 MVA ICT and shall take start up
power to start its unit.
9) 66 kV Bus at Udaipur Sub-Station shall be charged through (1 X 15 + 2 X 10) MVA ICTs
at Udaipur Sub-Station. Load at Udaipur shall be connected by SLDC, Tripura in co-
ordination with NERLDC.
10) Udaipur Sub-Station shall extend power to 132 /66 kV Gumti Power Station through 66
kV S/C Udaipur – Gumti line.
11) Gumti Power Station shall bring generation if required and synchronize with this Island.
12) 132 kV Agartala Sub-Station shall extend power to 132 kV Dhalabil Sub-Station through
132 kV S/C Agartala – Dhalabil line. Load at Dhalabil shall be connected by SLDC,
Tripura in co-ordination with NERLDC.
13) Dhalabil Sub-Station shall extend power to 132 kV Kamalpur Sub-Station through 132
kV S/C Dhalabil –Kamalpur line. Load at Kamalpur shall be connected by SLDC,
Tripura in co-ordination with NERLDC.
14) Kamalpur Sub-Station shall extend power to 132 kV P K Bari Sub-Station through 132
kV S/C Kamalpur – P K Bari line. Load at P K Bari shall be connected by SLDC,
Tripura in co-ordination with NERLDC.
15) P K Bari Sub-Station shall extend power to 132 kV Dharmanagar Sub-Station through
132 kV S/C P K Bari – Dharmanagar line. Load at Dharmanagar shall be connected by
SLDC, Tripura in co-ordination with NERLDC.
16) 132 kV Dharmanagar Sub-Station shall extend power to 132 kV 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 connected by SLDC,
Tripura in co-ordination with NERLDC.
17) 132 kV P K Bari Sub-Station shall extend power to 132 kV Kumarghat Sub-Station
through 132 kV S/C P K Bari – Kumarghat line.
18) 132 kV P.K.Bari Sub-Station shall extend power to 132 kV Ambassa Sub-Station
through 132 kV S/C P K Bari – Ambassa line. Load at Ambassa shall be connected by
SLDC, Tripura in co-ordination with NERLDC. 132 kV Baramura – Gamaitila -
Ambassa lines shall be closed.
19) 132 kV P K Bari Sub-Station shall extend power to 400/132 kV Silchar (PG) Sub-Station
through charging of any one of the 132 kV D/C P K Bari – Silchar line.
Restoration of Mizoram system
20) 132 kV AGTPP shall extend power to 132 kV Kumarghat Sub-Station through 132 kV
S/C AGTPP – Kumarghat line.
21) Kumarghat Sub-Station shall extend power to 132 kV Aizawl Sub-Station through 132
kV S/C Kumarghat – Aizawl line.
22) 132 kV Aizawl (PG) Sub-Station shall extend power to 132 kV Zuangtui & 132 kV
Luangmual Sub-Station through 132 kV S/C Aizawl – Zuangtui & 132 kV Aizawl –
Luangmual Lines. Load at Zuangtui & Luangmual shall be connected by SLDC,
Mizoram in co-ordination with NERLDC. If required, Bus Reactor at Kumarghat and
Aizawl Sub-Stations shall be taken into service to contain over-voltage.
24) 132 kV Aizwal (PG) Sub-Station shall extend power to 132 kV Kolasib (Mizoram) Sub-
Station through 132 kV S/C Aizwal - Kolasib line. Load at Kolasib shall be connected by
SLDC, Mizoram in co-ordination with NERLDC. 132 kV Kolasib Sub-Station shall
extend power to 132/66 kV Bairabi (Mizoram) Power Station for survival/auxiliary
power through 66 kV Kolasib – Bairabi line.
Restoration of south Assam system
25) 132 kV Kumarghat (PG) Sub-Station shall extend power to 132 kV Badarpur (PG) Sub-
Station through 132 kV S/C Kumarghat - Badarpur line.
26) 132 kV Badarpur Sub-Station shall extend power to 132 kV Panchgram (Assam) Sub-
Station through 132 kV S/C Badarpur – Panchgram line. Then, Badarpur shall extend
power to 400/132 kV Silchar through any one of 132 kV D/C Badarpur – Silchar lines.
27) Silchar Sub-Station shall extend power to 132 kV Srikona Sub-Station through any one
of 132 kV D/C Silchar – Srikona lines. Again, Silchar Sub-Station shall charge any one
of 400 kV Bus through 400 / 132 kV, 2x 200 MVA ICT. All the Bus reactors at Silchar
Sub–station shall be put into service to contain service. Silchar Sub-Station shall extend
to power 400/132 kV Palatana power Station through any one of 400 kV Silchar –
Palatana lines, If voltage permits, otherwise wait till voltage falls within permissible
limit.
28) Again, 400/132 kV Silchar(PG) station can receive power from 132 kV PK Bari
substation through charging of any one of 132 kV PK Bari-Silchar lines.Then , 132 kV
Panchgram Sub-Station can receive power from Silchar Sub-station through 132 kV S/C
Silchar - Panchgram line. Then, Panchgram Sub-Station can extend power to Badarpur
(PG) through 132 kV Panchgram – Badarpur line.Also Badarpur(PG) can receive power
from Silchar substation through charging of any one of 132 kV D/C Silchar-Badarpur
lines.
29) 132 kV Panchgram Sub-Station shall extend power to Srikona (Assam) Sub-Station
through 132 kV S/C Panchgram – Srikona line. Also Silchar substation can extend power
to Srikona through any one of 132 kV D/C Silchar-Srikona lines. Load at Panchgram and
Srikona shall be connected in co-ordination with SLDC, Assam.
30) 132 kV Badarpur Sub-Station shall extend power to 132 kV Khliehriat (PG) Sub-Station
through 132 kV S/C Badarpur – Khliehriat line.
31) Tripura Island shall be synchronized with Meghalaya Island at 132 kV Khliehriat (PG)
through any one of 132 kV D/C Khliehriat – Khliehriat lines.
32) Tripura Island shall be synchronized with Loktak Island at 132 kV Badarpur (PG)
through 132 kV Badarpur – Jiribam line.
5.2.2 Formation Loktak (NHPC) Island comprising of Manipur and Nagaland
This Island comprising of Loktak (NHPC) power station with Manipur and part of Nagaland
which consist of following Sub stations and Power stations:
Sub Stations:
(a) 132 kV Ninthoukhang (Manipur)
(b) 132 kV Churachandpu (Manipur)
(c) 132 kV Imphal (Manipur)
(d) 132 kV Imphal (PG)
(e) 132 kV Karong (Manipur)
(f) 132 kV Kohima (Nagaland)
(g) 132 kV Dimapur (Nagaland)
(h) 132 kV Dimapur (Powergrid)
Power-stations:
(a) 132 kV Loktak (NHPC)
(b) 132 kV Doyang ( NEEPCO)
(c) 132 kV Likhiro (Nagaland)
The Island is formed by availing black start power from Loktak power-station. Black start
facility of Doyang is not explored fully due to fewer loads connected with Doyang as well
as highly unstable behavior of machine.
estoration of Loktak (NHPC) Island comprising of Manipur and Nagaland system
Restoration of Manipur system
1) 132 kV Loktak (NHPC) Power Station shall black start and charge 132 kV Bus.
2) Loktak Power Station shall extend power to 132 kV Imphal (PG) and 132 kV
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
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in co-ordination with SLDC, Manipur. Loktak Power Station shall bring and
synchronize other machines.
3) 132 kV Imphal (PG) Sub-Station shall extend power to 132 kV Imphal (Manipur) Sub-
Station through any one of 132 kV D/C Imphal – Imphal lines. Load at Imphal (Manipur)
shall be connected by SLDC, Manipur in co-ordination with NERLDC.
4) 132 kV Ningthoukong Sub-Station shall extend power to 132 kV Churachandpur Sub-
Stations through 132 kV S/C Ningthoukong – Churachandpur line. Load at
Churachandpur shall be connected by SLDC, Manipur in co-ordination with NERLDC.
132 kV S/C Ningthoukong – Imphal (PG) line shall be closed.
5) 132 kV Imphal (Manipur) Sub-Station shall extend power to 132 kV Karong and 132 kV
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
connected by SLDC, Manipur in co-ordination with NERLDC.
6) Loktak Power Station shall extend power to 132 kV Jiribam (PG) & 132 kV 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 by SLDC, Manipur in
co-ordination with NERLDC.
7) 33 kV Bus at Jiribam (PG) Sub-Station shall be charged through 1X20 MVA ICT at
Jiribam (PG) Sub-Station. Load at Jiribam shall be connected by SLDC, Manipur in co-
ordination with NERLDC.
8) 132/33 kV Jiribam (PG) Sub-Station shall extend power to 132 kV Pailapool (Assam)
Sub-Station through 132 kV S/C Jiribam – Pailapool line. Load at Pailapool shall be
connected by SLDC, Assam in co-ordination with NERLDC and startup power to be
extended to Baskandi Power Station for bringing of their machines.
Restoration of Nagaland system
9) 132 kV 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.
10) 220/132 kV Dimapur (PG) Sub-Station shall extend power to 132 kV Dimapur
(Nagaland) Sub-Station through any of 132 kV D/C Dimapur – Dimapur line. Load at
Dimapur (Nagaland) shall be connected by SLDC, Nagaland in co-ordination with
NERLDC.
11) Dimapur (PG) Sub-Station shall extend power to 132 kV Kohima Sub-Station through
132 kV S/C Dimapur – Kohima line. Load at Kohima shall be connected by SLDC,
Nagaland in co-ordination with NERLDC Kohima Sub-Station shall extend power to
132 kV Meluri Sub-Station through 132 kV S/C Kohima – Meluri line. Load at Meluri
shall be connected by SLDC, Nagaland in co-ordination with NERLDC.
12) 132 kV Meluri Sub-Station shall extend power to 132/66 kV Khiphire Sub-Station
through 132 kV S/C Meluri – Khiphire line. Load at Khiphire shall be connected by
SLDC, Nagaland in co-ordination with NERLDC.
13) 66 kV Bus at Khiphire Sub-Station shall be charged through any one of 3X6.5 MVA
ICT at Khiphire Sub-Station.
14) 132/66 kV Khiphire Sub-Station shall extend power to 66kV Likhimro Power Station
through 66 kV Khiphire – Likhimro line.
15) 220/132 kV Dimapur (PG) Sub-Station shall extend power to 132 kV 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.
16) Doyang (NEEPCO) Power Station shall extend power to 132 kV Mokokchung Sub-
Station through 132 kV S/C Doyang – Mokukchung line. Load at Mokokchung shall be
connected by SLDC, Nagaland in co-ordination with NERLDC.
17) This island shall be synchronized with Tripura Island at Badarpur (PG) Sub-station through
132 kV S/C Badarpur – Jiribam line.
18) This island can also be synchronized with Tripura Island Silchar (PG) sub-station through
charging of any one of 132 kV D/C Silchar (PG)-Imphal(PG) line.
19) This island shall be synchronized with Upper Assam Island at 220/132 kV Dimapur
(PG) through 132 kV S/C Mariani –Golaghat-Bokajan- Dimapur line.
Note: SLDC, Nagaland, Manipur and south Assam shall co-ordinate with NERLDC
before connecting loads to their systems.
5.2.3 Formation of Upper Assam Island comprising of Dibrugarh, Nazira andTinsukia sub-
stations
This Island comprising of Upper Assam sytem which consist of following Sub stations and
Power stations:
Sub Stations:
(a) 132 kV Dibrugarh
(b) 132 kV Nazira
(c) 220/132 kV Tinsukia
(d) 132 kV Jorhat
(e) 132 kV Golaghat
(f) 220/132 kV Mariani
Power-stations: 132 kV NTPS and 132 kV LTPS;
The Island is formed by availing black start power from NTPS power-station
estoration procedures for Upper Assam Island:
1) 132/66 kV 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) 132 kV Bus at NTPS shall be charged through any one of 2X25 MVA ICT at NTPS.
3) NTPS shall extend power to 132 /66 kV LTPS (Assam) through any one of 132 kV D/C
LTPS – NTPS lines. LTPS shall bring generation and synchronize.
4) NTPS shall extend power to 220/132/66kV Tinsukia & 132/66 kV 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.
5) NTPS shall also extend power to 220/132/66 kV Tinsukia (Assam) Sub-Station through
132 kV S/C NTPS -Tinsukia line.
6) 220/132/66 kV Tinsukia substation shall extend power to 132 kV Dibrugarh (Assam)
Sub-Station through 132 kV S/C Tinsukia – Dibrugarh line. Load at Dibrugarh shall be
connected in co-ordination with SLDC Assam. 132 kV LTPS – Nazira line shall be
closed.
7) LTPS shall extend power to 220/132 kV 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.
8) This island shall be synchronized with Loktak Island at 220/132 kV Dimapur (PG)
substation through 132 kV Mariani (Assam) - Golaghat-Bokajan-Dimapur (PG) line.
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5.2.4 Formation Formation Meghalaya Island with capital load of Assam
This Island comprising of Meghalaya sytem which consist of following Sub stations and
Power stations:
Sub Stations:
(a) 132 kV Mawlai
(b) 132 kV Nehu
(c) 132 kV Khliehriat
(d) 132 kV Lumsnong
(e) 132 kV NEIGRIHMS
(f) 132 kV Umium
(g) 132 kV Sarusajai (Assam)
(h) 132 kV Kahilipara (Assam)
The Island is formed by availing black start power from Umium Stage 1 power-station
estoration procedures for Meghalaya Island
1) 132 kV Umiam Stg I Power Station shall black-start and charge 132 kV Bus at Umiam St I
Power Station. 132 kV Umiam Stg III Power Station shall also black start and charge132 kV
Bus at Umiam Stg III Power Station.
2) Umiam Stg I Power Station shall synchronize with Umiam Stg III Power Station at Umium
Stg III Power Station through any one of 132 kV D/C Umiam Stg I – Umiam Stg III lines.
Umiam Stg I & III Power Stations shall bring and synchronize other machines. Load at
Umiam Stg III shall be connected in co-ordination with SLDC Meghalaya.
3) Umiam Stg I Power Station shall extend power to Umiam Stg II Power Station through 132
kV S/C Umiam Stg I – Umiam II line for survival/auxiliary power. Umiam St II Power
Station shall bring generation if required and synchronize.
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Power-stations:
(a) 132 kV Umium Stage 1
(b) 132 kV Umium Stage 2
(c) 132 kV Umium Stage 3
(d) 132 kV Umium Stage 4
(e) 132 kV Umtru
(f) 132 kV Leshka
4) Umiam Stg III Power Station shall extend power to 132 kV Umiam Stg IV Power Station
through any one of 132 kV D/C Umiam Stg III – Umiam IV line for survival/auxiliary
power. Umiam Stg IV Power Station shall bring generation if required and synchronize.
5) Umiam Stg III Power Station shall extend power to 132 kV Umtru Power Station through
any one of 132 kV D/C Umiam Stg 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) 132 kV Umtru Power station shall extend power to 132 kV EPIP II (Norbong) substation
through any one of 132 kV D/C Umtru-Norbong lines.
7) 400/220/132 kV Byrnihat Substation shall be charged after extending power from 132 kV
EPIP II substation through any one of 132 kV D/C Norbong-Byrnihat lines.
8) 220 kV bus of 400/220/132 kV Byrnihat substation will be charged through one of 2 x 160
MVA, 220/132 kV, ICTs.
9) Umiam Stg I Power Station shall extend power to 132 kV Mawlai and 132 kV NEHU Sub-
Stations through 132 kV S/C Umiam Stg I – Mawlai line and 132 kV S/C Umiam Stg I –
Umiam - NEHU line respectively. Load at Mawlai, Umiam and NEHU shall be connected
in co-ordination with SLDC Meghalaya.
10) NEHU Sub-Station shall extend power to 132 kV 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.
11) 132 kV Khliehriat Sub-Station shall extend power to 132 kV Lumsnong Sub-Station
through 132 kV S/C Khliehriat- Lumsnong line. Load at Lumsnong shall be connected in
co-ordination with SLDC Meghalaya.
12) Again, Power shall be extended to 132 kV Leshka power station from Khliehriat
(Meghalaya) Sub-Station through 132 kV D/C Khliehriat – Leshka lines.
13) This island shall be synchronized with ISLAND F at 400/220/132 kV Byrnihat (Meghalaya)
Sub-Station through any one of 220 kV D/C Misa - Byrnihat lines.
14) This island shall be synchronized with ISLAND F at 132 kV Khliehriat (PG) Sub-Station
through any one of 132 kV D/C Khliehriat – Khliehriat lines.
15) 132 kV Umtru (Meghalaya) Power Station shall extend power to 220/132 kV 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.
16) Umtru (Meghalaya) Power Station shall extend power to 132 kV 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.
5.2.5 Restoration of other part of the network comprising of Central Assam, Anunachal Pradesh
and rest of NER Grid
1) 132 kV Badarpur Sub-Station shall extend power to 132 kV Khliehriat (PG) Sub-Station
through 132 kV S/C Badarpur – Khliehriat line.
2) Tripura Island shall be synchronized with Meghalaya Island at 132 kV Khliehriat (PG)
through any one of 132 kV D/C Khliehriat – Khliehriat lines.
3) 132 kV Khandong (NEEPCO) Power Station shall black start one of three machines &
charge 132 kV Bus. Otherwise, Khandong power station shall take startup power from 132
kV Khliehriat (PG) Sub-station. Khandong Power Station shall extend power to 132 kV
Haflong (PG) Sub-Stations and 132 kV Umrangshoo (Assam) substation through 132 kV
Khandong –Umrangshoo- Haflong line.
4) Haflong (PG) Sub-Station shall extend power to 132 kV Haflong (Assam) Sub-Stations
through 132 kV Haflong (PG) – Haflong (Assam) line. Load at Haflong shall be connected
in co-ordination with SLDC, Assam
5) Khandong Power Station shall extend power to 220/132 kV 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.
6) Kopili Power Station shall extend power to 400/220 kV Misa (PG) Sub-Station through any
one of 220 T/C Kopili – Misa lines.
7) 400/220 kV Misa Sub-Station shall extend power to 220/132 kV Samaguri (Assam) Sub-
Station through any one of 220 kV D/C Misa – Samaguri lines.132 kV bus at Samaguri
Sub-Station shall be charged through any one of 3 x 50 MVA ICT.Load at Samaguri shall
be connected in co-ordination with SLDC, Assam
After synchronization of the above Islands together at 132 kV Badarpur (PG), 132 kV
Khliehriat (PG), 220/132 kV Dimapur (PG) and 220/132 kV Mariani (Assam) Sub-Stations,
balance elements of the system shall be restored at the earliest to build up total NER Grid. To
contain over voltage, charging of 400 kV lines and 220 kV lines shall be avoided initially as the
Grid may not able to absorb any jerk due to tripping of line on over voltage. 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 400/220/132
kV Balipara, 132 kV Khupi, 132 kV Kimi, 132 kV Gohpur, 132 kV Nirjuli, 132 kV Itanagar, 132
kV Lekhi, 400/132 kV Biswanath Chariali(PG),400/132 kV Ranganadi, 132 kV Ziro, 132 kV
Daporijo, 132 kV Along, 132 kV North Lakhimpur , 132 kV Dhemaji, 132 kV Majuli, 132 kV
Rangia, 132 kV Rowta, 132 kV Sipajhar, 132 kV Depota, 132 kV Sonabil,132 kV Pavoi,132 kV
Barnagar, 132 kV Nalbari, 132 kV Dhaligaon, 132 kV BTPS, 220kV AGBPP and 220 kV
Deomali Sub-Stations/power stations are as followed:
1) 220/132 kV Mariani Sub-Station shall extend power to 220 kV AGBPP (NEEPCO) through
220 kV S/C Mariani – AGBPP line. 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) 220/132 kV Samaguri Sub-Station shall extend power to 400/220/132 kV Balipara Sub-
Station through 220 kV S/C Samaguri – Balipara line. Any one of 132 kV Bus(s) at
Balipara Sub-Station shall be charged through any one of 2X50 MVA ICT.
3) Balipara Sub-Station shall extend power to 132 kV Khupi & 132 kV Kimi Sub-Stations
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 132 kV Sonabil Sub-Station and 132 kV
Depota Sub-Station through 132 kV S/C Balipara –Sonabil line and 132 kV Balipara-
Depota line. Load at Depota shall be connected in co-ordination with SLDC, Assam.
5) 132 kV Sonabil substation shall extend power to 132 kV Gohpur substation and 132 kV
Pavoi substation through 132 kV S/C Sonabil-Gohpur line and 132 kV S/C Sonabil-Pavoi
line respectively.
6) 132 kV Gohpur Sub-Station shall extend power to 132 kV 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.
7) Power will be extended to 400/132 kV Biswanath Chariali(PG) substation through one of
132 kV D/C Biswanath Chariali(PG)-Pavoi(Assam) lines.
8) 132 kV Gohpur Sub-Stations shall extend power to 132 kV 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.
9) 132 kV Nirjuli Sub-Station shall extend power to 400/132 kV Ranganadi (NEEPCO) Power
Station through 132 kV S/C Nirjuli –Lekhi - Ranganadi line. Load at Lekhi shall be
connected in co-ordination with SLDC, Arunachal Pradesh.
10) Ranganadi Power Station shall extend power to 132 kV 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-ordination with SLDC, Arunachal Pradesh.
11) 132 kV Kahilipara Sub-Station shall extend power to 132 kV Rangia and 220/132 kV
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.
12) 132 kV Rangia Sub-Station shall extend power to Rowta (Assam) and 132 kV 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.
13) Rangia Sub-Station shall extend power to 132 kV Barnagar, 132 kV Nalbari and 132 kV
Dhaligaon (Assam) Sub-Stations through 132 kV S/C Rangia – Barnagar-Dhaligaon line
and 132 kV S/C Rangia – Nalbari - Dhaligaon line respectively. Loads at Nalbari, Barnagar
and Dhaligaon shall be connected in co-ordination with SLDC, Assam.
14) Dhaligaon Sub-Station shall extend power to 220/132 kV BTPS (Assam) Sub-Station
through any one of 132 kV D/C Dhaligaon – BTPS lines.
15) BTPS Sub-Station shall extend power to 220/132 kV 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 132 kV
Gelephu (Bhutan) Sub-Station through 132 kV Salakati – Gelephu Line (International Line).
Gelephu can also receive power from Rangia (Assam) Sub-Station via Motonga (Bhutan)
Sub-Station through 132 kV S/C Rangia – Motonga line.
16) Again, 220/132 kV Salakati Sub-station shall extend power to 400/220 kV Bongaigaon Sub-
Station Sub-Station though (1x315) MVA ICT. To contain voltage within stipulated limit,
the bus reactors at Bongaigaon Sub-Station shall be put into service.Bongaigaon Sub-
Station shall extend power to 400/220 kV BTPS(NTPC) through any one of 400 kV (D/C)
Bongaigaon – BTPS lines.
17) Any one of 220 kV D/C Samaguri – Sarusajai lines shall be closed. Sarusajai Sub-Station
shall extend power to 400/220 kV Azara Sub-Station through any one of 220 kV(D/C)
Sarusajai – Azara lines. Azara shall extend power to Agia and Boko through 220 kV Azara-
Agia and 220 kV Azara – Boko lines respectively. Load at Agia and Boko shall be
connected in co-ordination with SLDC, Assam.
18) 220/132 kV Agia Sub-Station shall extend power to BTPS Sub-Station through one of 220
kV (D/C) BTPS – Agia line.
19) 400/220 kV Balipara Sub-Station may charge one of 400 kV Bus(s) through 315 MVA ICT.
Tertiary Reactors at Balipara Sub-Station shall be taken into service to contain voltage.
Balipara Sub-Station can charge any one of 400 kV Q/C Balipara – Biswanath Chariali
lines if voltage permits. If required, Bus Reactor at Balipara Sub-Station may be taken into
service to contain voltage.
20) Biswanath Chariali Sub-Station can charge any one of 400 kV D/C Ranganadi – Biswanath
Chariali lines if voltage permits.
21) 400/220 kV Misa (PG) Sub-Station shall charge 400 kV Bus through 315 MVA ICT.
Tertiary Reactors 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.
22) Misa Sub-Station shall extend power to 400/220/132 kV 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 132 kV 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 132 kV 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.
23) 400/132 kV 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.
24) Any one of 400 kV (Q/C) Balipara – Bongaigaon lines shall be taken into service before
synchronizing the NER Grid with NEWS Grid at Bongaigaon Sub-Station. If the system
voltage permits, either one of 400 KV Silchar – Azara-Bongaigaon or 400 kV Silchar -
Byrnihat -Bongaigaon line may be taken into service.
25) Whenever ER power is available, NER Grid shall be synchronized with ER Grid at 220/132
kVSalakati Sub-Station 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 Q/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.
5.3 Restoration Restoration of 400 / 220 / 132 kV Southern part of Network
comprising of Manipur, South Assam, Mizoram, Tripura, part of Meghalaya ,
AGTPP and Palatana after partial collapse
In case of partial disturbance following process are adopted for restoration of Southern part
of Network comprising of Manipur, South Assam, and Mizoram, and Tripura, part of
Meghalaya, AGTPP and Palatana. After the Black out the nearest source of available power
shall be explored. If Power can be taken from 400 kV Bongaigaon sub staion through 400
kV Bongaigaon – Azara – Silchar line or 400 kV Bongaigaon – Byrnihat – Silchar line
formation of Tripura and Loktak Islands (as discussed in section 5.1) may not be required
because power can directly extend to Loktak (NHPC) and AGTPP (NEEPCO) power
stations through 132 kV Imphal (PG) and 132 Kumarghat sub stations respectively.
Otherwise, Power shall be taken from 400 / 220 kV Misa Sub station and 220/132 kV
Dimapur sub station. In that situation Loktak power station can receive power from 220/132
kV Dimapur sub station thorugh 132 kV Imphal sub station. As extension of power from
400 / 220 kV Misa Sub station to AGTPP power station and other part of the southern part
of network may take considerable time Formation of Tripura Island with AGTPP power
station shall be envisaged to reduce the restoration time.
The restoration procedures are as follow:
Restoration of Tripura system, AGTPP(NEEPCO) and Palatana power station
1) 132/66 kV 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 132 kV 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) 132 kV AGTPP (NEEPCO) shall black start one of its unit and charge 132 kV Bus at
AGTPP. AGTPP shall synchronize Tripura System through any one of 132 kV D/C AGTPP
– Agartala lines. AGTPP shall bring and synchronize other machines.
5) Agartala Sub-Station shall extend power to 132 /66 kV 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) 132 kV Budhjangnagar shall extend power to Surjyamani Nagar through 132 kV
Budhjangnagar - Surjyamani Nagar line.Then Surjyamani Nagar shall extend power to
Palatana through 132 kV S Nagar – Palatana line.
7) 132 kV Rokhia Power Station shall extend power to 132 kV Udaipur Sub-Station through
132 kV S/C Rokhia – Udaipur line. Udaipur shall extend power to 400/132 kV Palatana
power station through 132 kV Udaipur – Palatana line.
8) Palatana shall charge 400 kV bus through 1x125 MVA ICT and shall take startup power to
synchronise its unit.
9) 66 kV Bus at Udaipur Sub-Station shall be charged through (1 X 15 + 2 X 10) MVA ICTs at
Udaipur Sub-Station. Load at Udaipur shall be connected in co-ordination with SLDC,
Tripura.
10) Udaipur Sub-Station shall extend power to Gumti Power Station through 66 kV S/C
Udaipur – Gumti line.
11) Gumti Power Station shall bring generation if required and synchronize with this Island.
12) 132 kV Agartala Sub-Station shall extend power to 132 kV Dhalabil Sub-Station through
132 kV S/C Agartala – Dhalabil line. Load at Dhalabil shall be connected in co-ordination
with SLDC, Tripura.
13) 132 kV Dhalabil Sub-Station shall extend power to 132 kV Kamalpur Sub-Station through
132 kV S/C Dhalabil –Kamalpur line. Load at Kamalpur shall be connected in co-
ordination with SLDC, Tripura.
14) 132 kV Kamalpur Sub-Station shall extend power to 132 kV 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-
ordination with SLDC, Tripura.
15) 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.
16) 132 kV Dharmanagar Sub-Station shall extend power to 132 kV 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 connected in co-ordination with
SLDC, Assam.
17) 132 kV P K Bari Sub-Station shall extend power to Kumarghat Sub-Station through 132 kV
S/C P K Bari – Kumarghat line.
18) 132 kV P.K.Bari Sub-Station shall extend power to 132 kV 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.
19) 132 kV P K Bari Sub-Station shall extend power to 400/132 kV Silchar(PG) Sub-Station
through charging of any one of the 132 kV D/C P K Bari – Silchar line.
Restoration of Mizoram system
20) 132 kV AGTPP shall extend power to Kumarghat Sub-Station through 132 kV S/C AGTPP
– Kumarghat line.
21) 132 kV Kumarghat Sub-Station shall extend power to 132 kV Aizawl Sub-Station through
132 kV S/C Kumarghat – Aizawl line.
22) 132 kV Aizawl (PG) Sub-Station shall extend power to Zuangtui & Luangmual Sub-Station
through 132 kV S/C Aizawl – Zuangtui & 132 kV Aizawl – Luangmual Lines. Load at
Zuangtui & Luangmual shall be connected in co-ordination with SLDC, Mizoram.
23) If required, Bus Reactor at Kumarghat and Aizawl Sub-Stations shall be taken into service
to contain voltage.
24) This island shall be synchronized with Main Grid at 132 kV Badarpur (PG) Sub-Station
through 132 kV S/C Kumarghat - Badarpur line.
25) This island shall be synchronized with Main Grid at 132 kV Aizwal (PG) Sub-Station
through 132 kV S/C Jiribam – Aizwal line.
26) If Black start of this Island is not possible then 132 kV Kumarghat Sub-Station shall take
power from 132 kV Badarpur (PG) Sub-Station through 132 kV S/C Badarpur – Kumarghat
line. Then, 132 kV AGTPP power station shall receive startup power through 132 kV S/C
Kumarghat – AGTPP line.
Restoration of South Assam system
27) 400/220 kV Misa sub substiaon shall extend power to 220/132 kV Kopili (NEEPCO) Power
Station through any two nos of 220 kV T/C Misa – Kopili Lines. 220/132 kV Kopili
(NEEPCO) Power Station shall charge 132 kV Bus through 160 MVA ICT. Kopili Power
Station shall extend power to 132 kV Khandong (NEEPCO) Power Station through any one
of 132 kV D/C Kopili – Khandong lines. Khandong Power Station shall bring machines and
synchronize.
28) Khandong (NEEPCO) Power Station shall extend power to 132 kV Haflong (PG) and 132
kV Khliehriat (PG) Sub-Stations through 132 kV S/C Khandong – Haflong and any one of
132 kV D/C Khandong - Khliehriat lines respectively.
29) 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.
30) 132 kV Khliehriat (PG) Sub-Station shall extend power to 132 kV Badarpur (PG) Sub-
Station through 132 kV S/C Khliehriat – Badarpur line.
31) 400/220/132 kV Byrnihat (Meghalaya) Sub-Station shall extend power to 400/132 kV
Silchar Sub – Station through 400 kV Byrnihat – Silchar line.Silchar shall charge 132 kV
bus through any one of 2x200 MVA ICT.Reactors at Byrnihat and Silchar shall be put into
service,if required. Silchar Sub – Station can also receive power from 400/220 kV Azara
Sub – Station through 400 kV Azara – Silchar line.
32) Silchar Sub-Station shall extend power to 132 kV Panchgram and Dullavcherra Sub –
Stations through 132 kV S/C Silchar – Panchgram and 132 kV S/C Silchar – Dullavcherra
lines respectively.
33) Silchar Sub-Station shall extend power to 132 kV Badarpur (PG) and 132 kV Srikona
(Assam) Sub-Stations through any one of 132 kV D/C Silchar – Badarpur and 132 kV D/C
Silchar – Srikona lines recpectively.
34) Badarpur (PG) Sub-Station shall extend power to 132 kV 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.
35) Silchar shall extend power to 400/132 kV Palatana Power station through any one of 400
kV D/C Silchar – Palatana Lines.
36) 132 kV Panchgram (Assam) Sub-Station shall extend power to 132 kV Srikona (Assam)
Sub-Station through 132 kV S/C Panchgram –Srikona line. Load at Srikona (Assam) shall
be connected in co-ordination with SLDC, Assam.
Restoration of Manipur system
37) 220/132 kV Dimapur (PG) can extend power to 132 kV Imphal(PG) substation through 132
kV Dimapur(PG)-Imphal(PG) line.If closing of this line is not possible,132 kV Imphal(PG)
can also receive power from any one of 132 kV D/C Silchar(PG) - Imphal(PG) line.
38) 132 kV Imphal (PG) Sub-Station shall extend power to 132 kV Imphal (Manipur) Sub-Station
through any one of 132 kV D/C Imphal – Imphal lines. Load at Imphal (Manipur) shall be
connected in co-ordination with SLDC, Manipur.
39) 132 kV Imphal (PG) Sub-Station shall also extend power to 132 kV Loktak power station
through 132 kV Loktak-Imphal (PG) line. Also 132 kV Loktak (NHPC) Power Station can be
black started and charge 132 kV Bus if power from Imphal (PG) is delayed.
40) Loktak Power Station shall extend power to 132 kV Ningthoukong Sub-Stations through 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.
41) 132 kV Ningthoukong Sub-Station shall extend power to 132 kV 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 (PG)
line shall be closed.
42) 132 kV Imphal (Manipur) Sub-Station shall extend power to 132 kV Karong and 132 kV
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 connected in
co-ordination with SLDC, Manipur.
43) Loktak Power Station shall extend power to 132 kV Jiribam (PG) & 132 kV 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.
44) 33 kV Bus at Jiribam (PG) Sub-Station shall be charged through 1X20 MVA ICT at Jiribam
(PG) Sub-Station. Load at Jiribam shall be connected in co-ordination with SLDC, Manipur.
Note: SLDC, Manipur, Assam, Tripura and Mizoram shall co-ordinate with NERLDC, during the
restoration period, for connecting loads
Restoration of part of Meghalaya system
Meghalaya netwok is usually kept segregated in 132 kV Nehu sub station and 132 kV Umium sub
station to avoid loading of some internal lines. Restoration of this part is also required after the
disturbance. Following procedures are adopted for restoration of the part:
1) 132 kV Khliehriat (PG) sub station shall extend power to 132 kV Khliehriat (S) sub station
through any one of 132 kV Khliehriat – Khliehriat lines.
2) 132 kV Khliehriat (S) sub station shall extend power to Lumsnong sub station though 132
kV Khliehriat – Lumsnong line.
3) 132 kV Khliehriat sub station shall extend power to NEHU and NEIGRIHMS sub stations
through 132 kV Khliehriat – NEHU and 132 kV Khliehriat – NEIGRIHMS lines. Load at
Lumsnong, NEHU and NEIGRIHMS shall be connected in co-ordination with SLDC,
Meghalaya.
CHAPTER 6: REPORTING PROCEDURES
This chapter deals with reporting procedures in respect of Grid Incidents/Grid Disturbance in the
system to all Users / STU / CTU, NERPC Secretariat and NLDC / NERLDC / SLDC. The reporting
procedure shall be in accordance with the relevant CEA Regulations.
6.1 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.
6.2 Scope
This chapter covers all Users, STU, CTU, NERPC Secretariat, NLDC, NERLDC and SLDCs.
6.3 Responsibility
i) The NERLDC/SLDC shall be responsible for reporting Grid Incidents/Grid Disturbance to the
Users, SLDC/STU, CTU / NLDC / NERLDC / NERPC 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 NERPC Secretariat for reporting Grid Incidents/Grid
Disturbance analysis as the case may be.
6.4 Categorisation of Grid Incidents and Grid Disturbance based on severity of trippings
The categorisation of Grid Incidents and Grid Disturbances shall be as follows
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
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
Categorisation of Grid Disturbance in increasing order of severity
o Category GD-1: When less than ten per cent. of the antecedent Generation or
load in a Regional Grid is lost;
o Category GD-2: When ten per cent. to less than twenty percent of the
antecedent Generation or Load in a Regional Grid is lost.
o 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;
o 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 ;
o 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.
6.5 Reporting of Grid Disturbance
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
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.
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.
NERLDC shall inform occurrence of the Grid disturbance to the constituents immediately and
to the NERPC at the earliest.
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.
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.
6.6 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 Incident/Grid Disturbance
vi) Duration of interruption and Demand and/or Generation (in MW and MWh) interrupted
vii) All Relevant system data including copies of records of all recording instruments
including Disturbance Recorder, Event Logger, DAS etc.
viii) 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 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.
ix) Details of Relay Flags.
x) Remedial measures.
6.7 Operational Data during Grid Incidents and Grid Disturbances
NERLDC shall classify the Grid Incidents and Grid Disturbances according to 6.4 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.
6.8 Operational Data Records
A record shall be kept of the number of Grid Incidents and Grid Disturbances of various
categories by the NERPC for each financial year.
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.
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