This document provides an overview of the Indian Electricity Grid Code (IEGC). It discusses the objectives and key contents of the IEGC, including the roles of various organizations in the electricity grid such as load dispatch centers, regulatory commissions, and transmission utilities. The IEGC aims to facilitate reliable, secure and economic operation of the national power grid in India. It defines operating procedures, planning guidelines, and responsibilities of grid participants.

1. INDIAN ELECTRICTY GRID
CODE
COURSE OBJECTIVE CO.4
Familiarization of global and national energy policies
Learning objective:
Familiarize with grid codes,roles of various organization
Familiarize with schedule and dispatch of electricity

2. What is IEGC?
2
“Describes the philosophy and the
responsibilities for planning and operation of
Indian power system specified by the
Commission in accordance with sub section
1(h) of Section 79 of the Act.”
Technical Rules
Guidelines
Operational Standards

3. IEGC
• to plan, develop, maintain and operate the power system, in the
most secure, reliable, economic and efficient manner.
• To facilitate healthy competition in the generation and supply of
electricity.

4. Key Words
4
CERC:Central Electricity Regulatory Commission
IEGC: Indian Electricity Grid Code
ISGS: Inter State Generating Station
ISTS: Inter State Transmission System
CTU: Central Transmission Utility
STU: State Transmission Utility
RPC: Regional Power Committee
STOA : Short Term Open Access

5. Evolution of IEGC
5
First draft prepared by POWERGRID as CTU in Mar-99
Approved by CERC in Jan 2000 after public hearing
Enforced w.e.f 01st Feb 2000
First revision by IEGC review panel
Issued on 22nd Feb 02, enforced w.e.f 01st April 2002
Second revision
Draft issued by CERC-June 2005, enforced from 1st April2006
Amendment
Public notice dated 23rd June 2006 by CERC
Comments/suggestions invited in respect of Regional Energy
Accounting (REA)

6. Objectives of IEGC
6
Documentation of the principles and procedures
Defines the relationship between the various Users of
the inter-State transmission system (ISTS), as well as
the Regional and State Load Despatch Centres
Facilitation of the operation, maintenance,
development and planning of economic and reliable
Regional Grid
Facilitation for beneficial trading of electricity by
defining a common basis of operation of the ISTS,
applicable to all the users of ISTS

7. Contents of IEGC
7
Role of various organizations and their linkages
Role of RLDC/RPC/CTU/CEA/SLDC/STU
Planning Code for inter-state transmission
Connection Conditions
Operation Code for Regional Grids
Operating philosophy, System security aspects
Demand management, Periodic reports
Operation liaison,Outage planning
Recovery procedures
Event information

8. 8
Scheduling & Despatch Code
Introduction, objective, Scope
Demarcation of responsibilities
Scheduling and despatch procedure
Reactive Power Control and Voltage Control
Complementary commercial mechanism
Regulatory requirements of special energy meters
Payment of reactive energy exchanges on state-owned
lines
Inter-regional Exchange Code
Management of IEGC
Contents of IEGC

9. Role of various agencies
9
Regional Load Despatch Centre
Regional Power Committee
Central Transmission Utility
Central Electricity Authority
State Transmission Utility
State Load Despatch Centre

10. Load dispatch centers

11. NLDC roles
• Monitoring of operations and grid security of the National Grid.
• Supervision and control over the inter-regional links may be required
for ensuring the stability of the power system under its control.
• Coordination with Regional Power Committees for regional outage
schedule in the national perspective to ensure optimal utilization of
power resources.
• Coordination with Regional Load Despatch Centers for the energy
accounting of inter-regional exchange of power.
• Coordination for the restoration of synchronous operation of the
national grid with Regional Load Despatch Centers.

12. Role of RLDC
12
2.2.1 According to sections 28 and 29 of Electricity
Act, 2003, the functions of RLDCs are as follows:
“The Regional Load Despatch Centre shall be the apex
body to ensure integrated operation of the power system
in the concerned region…”
“Every licensee, generating company, generating station,
substation and any other person connected with the
operation of the power system shall comply with the
directions issued by the Regional Load Despatch
Centres…”
“Dispute be referred to Central Commission for
decision..”

13. Role of RLDC
• be responsible for optimum scheduling and despatch of
electricity within the region in accordance with the contracts
entered into with the licensees or the generating companies
operating in the region.
• monitor grid operations.
• keep accounts of quantity of electricity transmitted through the
regional grid.
• exercise supervision and control over the inter-State
transmission system.
• be responsible for carrying out real time operation for grid
control and despatch of electricity within the region through
secure and economic operation of the regional grid in
accordance with the Grid standards and Grid code.

14. Role of RLDC
• Coordinating and issuing drawal schedules of State Power Utilities from all Central
Generating Stations and dispatch schedules of Central Generating Stations.
• Facilitating transactions of power under short-term and long term open access for
inter/intra regional exchanges following regulations and procedures issued by the
Central/State Electricity Regulatory Commission and Central Transmission Utilities.
• The RLDCs of the Region, where point of drawal of electricity is situated, shall be the
Nodal Agency for the short-term transmission access in case of open access in inter-State
transmission.
• Collecting the meter readings from all interconnected / boundary point, central
generating stations, computes the average energy for 15 minutes time block, compares
the deviations from the schedule and computes the unscheduled inter change (UI)
charges for the corresponding time block based on UI rates of average frequency during
the time block.
• Issuing clearance for outage of grid elements for maintenance work.

15. Role of RPC
15
 Undertake operation analysis for improving grid performance
 Facilitate inter-state/inter-regional transfer of power
 Facilitate all functions of planning relating to inter-state/ intrastate
transmission system with CTU/STU
 Coordinate planning of maintenance of generating machines &
transmission system on monthly basis
 Undertake operational planning studies including protection studies for
stable operation of the grid
 Review of reactive compensation requirement & monitoring of installed
capacitors
 Evolve consensus on all issues relating to economy and efficiency in the
operation
 Relay setting coordination
 Identify critical locations where bus bar protection needs to be provided, if
not available.
 Carry out periodic inspection of the under frequency relays and maintain
proper records of the inspection

16. 23
Role of CTU
Undertake transmission of electricity through inter-
State transmission system
Discharge all functions of planning and co-
ordination relating to ISTS with STU, Central
Government, State Governments, Generating
companies, Regional Power Committees, CEA,
Licensees
Ensure development of an efficient, coordinated
and economical system of ISTS for smooth flow of
electricity from generating stations to the load
centres
Provide non-discriminatory open access
Operate RLDCs

17. 24
Neutrality of CTU
provide non-discriminatory open access to its
transmission system (2.1.c)
“Until a Government company or authority or
corporation is notified by the Central
Government, the CTU shall operate RLDC”
(2.4.1.2)
“CTU shall not engage in the business of
generation of electricity or trading in
electricity” (2.4.2)

18. 25
Role of CEA
Formulate short-term and perspective plans
Specify/prepare/notify
Safety requirements for construction, operation and
maintenance
Grid Standards
Conditions for installation of meters
National Electricity Plan once in five years
Promote & assist in the timely completion of
schemes and projects
Collect and record data
Carry out studies relating to cost, efficiency,
competitiveness
Carry out investigation

19. Planning Code
19
Membership of the Standing Committee for
Transmission Planning
Dovetailing of the interstate transmission planning with
long-term Open Access approvals
Planning Criteria
N-1 contingency-Outage of series compensated line
Special Protection Scheme for Bipole trip
Reduction of transmission losses
Reconfiguration of transmission lines
Transition from 400 kV to 765 kV
Categorization of zones for generation investment/loadgrowth

20. Scheduling & Despatch Code
20
Scheduling timeline
Ramping Rate for peak
MW quantum of schedule revisions
Intra day open access
Termination transactions during congestion
Chopping of generation- 101 % & 105 % rule

21. Few examples of grid indiscipline
21
Non-compliance of RLDC instructions
Switching of ISTS elements without RLDC permission
(except under emergency)
Manning of control centres by inadequately qualified &
untrained trained personnel
Deliberately isolating part of the grid from the rest of the
regional grid
Suddenly reducing generating unit output by more
than one hundred (100) MW (20 MW in case of
North- Eastern region)
Sudden increase in its load by more than one hundred
(100 MW) (20 MW in case of North-Eastern region)

22. Few examples of grid indiscipline
22
Not ensuring providing of RTU and other
communication equipment for sending real-time data to
SLDC/RLDC at least before date of commercial
operation of the generating stations or sub-station/line
being connected to ISTS
Protection systems unable to isolate the faulty
equipments within the specified fault clearance time with
reliability, selectivity and sensitivity
Not sending information/data including disturbance
recorder/sequential event recorder output etc., to RLDC
for purpose of analysis of any grid disturbance/event.

23. 2.8. Role of STU (2.8.1 Sec 39 of the Act, 2003
(1) (a) intra-State electricity transmission;
(b) of planning and relating to intra-state transmission system
co-ordination with i) CTU ii) State Governments
iii) generating companies; iv) Regional Power Committees;
v) Authority; vi) licensees;
(c) to ensure development of an efficient, co-ordinated and economical system of intra-
State transmission lines
(d) to provide non-discriminatory open access to its transmission system
(2) STU to to operate the SLDC until a Government company or any authority or
corporation is notified by the State Government

24. CONNECTION CODE
4.6.1 Reactive Power Compensation
a) STU and users to provide Reactive Power compensation and/or
other facilities, close to the load points thereby avoiding the
need for exchange of Reactive Power to/from ISTS and to
maintain ISTS voltage within the specified range.
b) To provide additional reactive compensation as per RPC and RLDC
The Users and STUs shall provide information to RPC and RLDC
regarding the installation and healthiness of the reactive
compensation equipment on regular basis.
RPC shall regularly monitor the status in this regard.

25. CONNECTION CODE
4.6.2 Data and Communication Facilities
All users, STU and CTU to provide to RLDC :
Reliable and efficient speech & data communication systems
Systems to telemeter power system parameter such as flow, voltage and status of
switches/ transformer taps etc. in line with interface requirements and other
guideline made available by RLDC.
Establish data flow up to appropriate data collection point on CTU’s system,
provide the required facilities at their respective ends as specified in the
Connection Agreement
4.6.5 Cyber Security
All utilities shall have in place, a cyber security framework to identify the critical
cyber assets and protect them so as to support reliable operation of the grid.

26. OPERATING CODE
All the users to
5.1 (d) comply with the directions of RLDC /SLDC to ensure integrated grid
operation and for achieving the maximum economy and efficiency in the
operation of the power system.
5.1 (g) Develop a set of detailed operating procedures for each state grid in
consistent with IEGC
5.1 (h) The control rooms of the NLDC, RLDC, all SLDCs, power plants, substation of
132 kV and above, and any other control centres of all regional entities shall be
manned round the clock by qualified and adequately trained personnel. Training
requirements may be notified by the Commission from time to time, by orders.
5.2.(d) Intimate any tripping, as soon as possible, say within ten minutes of the
event. The reason (to the extent determined) and the likely time of restoration
shall also be intimated. All reasonable attempts shall be made for the elements’
restoration as soon as possible.

27. SRLDC
Frequency Control
• Operating Frequency Range revised - 49.5Hz to 50.2Hz
• Action for curtailing over drawal to be initiated at 49.7Hz
• No overdrawal when frequency is 49.5Hz or below
• Frequency Linked despatch guidelines to be followed
• All SEBs /distribution licensees shall abide by the demand management measures of the SLDCs
and comply the directions of SLDC. Any non-compliance shall be reported by SLDC to RLDC
• Automatic Load disconnection (Demand side Management) scheme shall be implemented by
the State utilities before 01.01.2011

28. 8/31/2023 SRLDC 28
Voltage Control
• Generating units of above 50MW size
shall have AVRs (Automatic Voltage
Regulators) in operation and PSS (Power
System Stabilizers) shall be got properly
tuned.
Operating Range of Voltage
Nominal Maximum Minimum
765 800 728
400 420 380
220 245 198
132 145 122
110 121 99
66 72 60
33 36 30

29. 8/31/2023 SRLDC 29
RGMO
FEATURES OF RGMO
• When system freq is below 50.2Hz, any improvement in frequency
shall not lead to reduction in generation.
• When system frequency is above 50.2Hz, any fall in frequency shall not
lead to increase in generation.
• Otherwise, for any fall in frequency, generation from the unit shall
increase by 5% limited to 105% of MCR (maximum continuous Rating)
subject to the Machine capability.
• Ripple filter of +/- 0.03 Hz. shall be provided so that small changes in
frequency are ignored for load correction, in order to prevent governor
hunting.

30. 8/31/2023 SRLDC 30
System Protection Schemes
• AUFR / df/dt Schemes:
• SLDC shall furnish the details of load relief on operation of AUFR or df/dt
to RLDC on real time basis.
• RLDC shall report such instances to RPC where there was no/inadequate
response.
• SLDC shall submit a monthly report to RPC in this regard
• RLDC shall submit a comparative record of expected load relief and
actual load relief obtained in Real time system operation to RPC and
CERC on monthly basis.
• SPS (SPECIAL PROTECTION SCHEMES) Shall be identified, installed and
commissioned to operate the transmission system closer to its limits and
to protect the same against voltage collapse, cascade tripping and
tripping of important corridors / flow gates

31. 8/31/2023 SRLDC 31
Demand Estimation
• Demand estimation for operational purposes is to be done on a
daily/weekly/monthly basis initially, mechanism and facilities at SLDCs
shall be created at the earliest but not later than 1.1.2011 to facilitate
on-line estimation of demand for daily operational use for each 15
minutes block.
• The monthly estimated demand by the SLDC shall be provided to RLDC
and RPC
• The SLDC shall take into account the Wind Energy forecasting to meet
the active and reactive power requirement.
• In order to facilitate estimation of Total Transfer Capability / Available
Transfer Capability on three month ahead basis , the SLDC shall furnish
estimated demand and availability data to RLDCs.

32. 8/31/2023 SRLDC 32
Demand side Management
• Contingency Procedure that enable demand disconnection as instructed
by RLDC / SLDC under normal and / or contingent condition
• State Electricity Boards/Distribution Licensees shall also formulate and
implement state-of-the-art demand management schemes for
automatic demand management like rotational load shedding, demand
response (which may include lower tariff for interruptible loads) etc.
before 01.01.2011. A Report detailing the scheme and periodic reports
on progress of implementation of the schemes shall be sent to the
Central Commission by the concerned SLDC.
• Grouping of Loads by SLDC without overlapping between different
Groups as given below
• Loads for scheduled power cuts/load shedding
• Loads for unscheduled load shedding
• Loads to be shed through under frequency relays/df/dt relays
• Loads to be shed under any System Protection Scheme identified at
the RPC level.

33. 8/31/2023 SRLDC 33
Communication System
Each User, STU, RLDC, NLDC and CTU shall provide and
maintain adequate and reliable communication facility
internally and with other Users / STUs / RLDC / SLDC to
ensure exchange of data / information necessary to
maintain reliability and security of the grid.

34. 8/31/2023 SRLDC 34
Restoration Procedure
• RLDC shall develop detailed plans and procedures for
• a)restoration of the regional grid under partial/total blackout and shall be
reviewed / updated annually.
• b) Detailed plans and procedures for restoration after partial/total blackout of
each User’s/STU/CTU system within a Region, will be finalized by the concerned
User’s/STU/CTU in coordination with the RLDC. The procedure will be reviewed,
confirmed and/or revised once every subsequent year. Mock trial runs of the
procedure for different subsystems shall be carried out by the Users/CTU/STU at
least once every six months under intimation to the RLDC. Diesel Generator sets
for black start would be tested on weekly basis and test report shall be sent to
RLDC on quarterly basis.
• c) List of generating stations with black start facility, inter-State / interregional ties,
synchronizing points and essential loads to be restored on priority, shall be
prepared and be available with NLDC, RLDC and SLDC.

35. REFERENCE
SOUTHERN REGIONAL LOAD DESPATCH CENTER
• POSOCO, POWERGRID, BANGALORE
• https://nrldc.in/
• http://www.cercind.gov.in/