CERC’sIndian Electricity Grid Code

Regulations, 2010By

Ravi KumarRavi PohaniRavi Rawat

Background

faultsharmonics Varying loads

Different generators

Timeline

March 99- planned by CTU

Jan 2000- approved by CEA

Feb 2000- Enforced

Feb 2002- Revised

April 2006- RevisedApril 2010- Revised

2006, 2008, 2009- Amended

Where does it come from?Electricity Act 2003

Section 79-(1)-(h)

Section 178-(2)-

(g)

Indian Electricity grid code

OBJECTIVES

Technical rules

Commercial rules

For all U

tilities connecte

d to or using ISTS

What’s its purpose?

rulesguidelines

standards

planning development maintenanceoperations

Power System (national and regional grids)

secure reliable

economic efficient

Competition in generation, supply, tradingBy defining a common basis for ISTS operations

forof

in

and

The way it goes

Roles and linkages between various

organizations

Planning code for ISTS

Conditions for connection• Procedure for

connecting to ISTS• Site Responsibility and

schedule

Operating Code for Regional Grids• Operating Policy• System Security

aspects• Demand estimation

and management• Periodic Reports• Outage Planning• Operational Liaison• Recovery Procedures• Event Information

Scheduling and Dispatch Code• Procedure for

scheduling ISGS• Complementary

Commercial Mechanism

• Modality of Flow Information between ISGS and load dispatch centers and other regional entities

Miscellaneous

ROLES OF VARIOUS ORGANIZATIONS (NLDC)

[section 26 (2) of Electricity Act 2003]

Supervising RLDC operationsMonitoring grid operations & security Giving operational feedback for the

proper functioning of national grid

Scheduling and dispatching of inter state electric transmission Coordinating with RLDC

For economic and reliable operations of Grid

Coordinating for international power exchange Levying fee for all such operations

ROLES OF VARIOUS ORGANIZATIONS (RLDC)

[ section 28 & 29 of Electricity Act 2003]

Control of ISGS scheduling Metering & data collectionInter-state Powertransmission

Operation of Ancillary Services and Operation of DSM pool account Reactive power account

ROLES OF VARIOUS ORGANIZATIONS (RPC)

[sec.29(4) sec.38(2.b) sec.39(2.b) of Electricity Act 2003]

Facilitate all functions of planning• Of inter-state/ intrastate transmission

system with CTU/STU• Monthly maintenance of generators &

transmission system• Operational & protection studies for

stable operation of the grid

Reviews reactive power compensation requirement and devices

Evolve consensus on performance and commercial issues of operation of the grid

ROLES OF VARIOUS ORGANIZATIONS (CTU)[sec. 38 of Electricity Act 2003]

Transmission of electricity through inter-state transmission system

Provide non-discriminatory open access

smooth flow of electricity from generating stations to the load centers between different states

Discharge all functions of planning and co-ordination ISTS with STU, central government, state governments, generating companies, regional power committees, CEA, licensees

ROLES OF VARIOUS ORGANIZATIONS (CEA)[sec.73 of Electricity Act 2003]

• National Electricity Plan in accordance with National Electricity Policy (in every 5 Years)

• Make short-term and perspective plans and specify/carry out• Technical standards for construction of electrical plants, electric

lines and connectivity to grid • Safety requirements for construction, operation and

maintenance of electrical plants and electric lines• Grid standards• Conditions for installation of meters • Promote & assist in achieving schemes and plans in time• Collection and recording of data• Feasibility and Performance studies• Carries out Investigations for purposes of generating or

transmitting or distributing electricity

ROLES OF VARIOUS ORGANIZATIONS (STU)[sec.39 of Electricity Act 2003]

• Undertake transmission of electricity through intra-state transmission system

• Discharge all functions of planning and co-ordination for • intra-state transmission system with CTU, state government,

generating companies, regional power committees, CEA & licensees

• Ensure smooth flow of electricity from generating stations to the load centers within the states

• Provide non-discriminatory open access

• Operate SLDC

secure

reliableeconomic

efficient

ROLES OF VARIOUS ORGANIZATIONS (SLDC)[section 32 of Electricity Act 2003]

• Permitting Open Access• Scheduling drawal from ISGS• Regulating net drawal• Demand Estimation in coordination with STU/DISCOM• Demand Regulation• Scheduling and dispatching

Planning Code• Objective: specifies principles and procedures for inter-state and inter-

regional planning and development; promotes coordination amongst regional constituents by providing methodology and information exchange

• Scope:• CTU• Transmission Licensee• ISGS• IPPs• SEBs• STUs• Licensees for transmission and generation

• CEA – transmission plan• CTU – plan system strengthening, taking advice from RPC CEA RLDC and

beneficiaries• CTU- nodal agency for long term transmission access• RLDC- for short term open access• Withstanding capacity of ISTS against- line and transformer outage• All generating units should work within the reactive power limits• Any one of these events defined above shall not cause:

• Loss of supply• Prolonged operation of the system frequency below and above specified

limits.• Unacceptable high or low voltage• System instability• Unacceptable overloading of ISTS elements.

Connection Code• CERC- grants connectivity for Long term and medium term open

access (abiding to grid standards by CEA)• Things to be taken care of while seeking connection:

• Reactive Power Compensation• Data and Communication Facilities• System Recording Instruments• Responsibilities for safety• Cyber Security• International connections to ISTS• Schedule of assets of Regional Grid

Operating Code

• System Security Aspects• Deliberate isolation of ISTS equipment not permitted• Operation of generating units in “RESTRICTED GOVERNOR MODE” and also

automatic voltage control• Sudden bulk change in generation and loading not permitted• Frequency band tightened from 49.9-50.05 Hz

Scheduling and dispatch code• It specifies:

• Responsibilities of SLDC and NLDC – different control areas – with different controllers- for balancing frequency of synchronously operating system- by controlling generation and maintain interchange schedule

• Procedure for scheduling and dispatch – foreseen MW cap of plant * state’s share in that capacity; (rest show in diagram)

• Reactive Power Control Mechanism-The Beneficiary pays for VAr drawal when voltage at the metering point is below 97% or above 103 % and is paid when VAr returned when voltage is below 97% and above 103% before metering point

• Voltage Control Mechanism• Commercial Mechanism

Control Area Concept

Scheduling Procedure

ISGS

RLDC8 10 15 18 22 23

SLDC

17

Station wise MW/MWh capacity

State wise MW/MWh entitlements

SLDC reviews own load forecasts and own generating schedules

PX file fromNLDC

Net drawal schedule

Power Plant dispatch schedule

Revision

Revision

Dispatch schedule for next day

Drawal Schedule

for next day

Collective Scheduling Procedure

NLDC11 13 14 16 17 17:30

Exchanges

RLDC final schedule for regional entities by 1800hrs

15

list of interfaces/control areas/ regional transmission systems on which unconstrained flows are required

total drawal and injection in each of the regions

period of congestion & available limit for scheduling

Scheduling Request of Collective Transaction

confirm acceptance

Application for Scheduling

interchange on various interfaces/control areas/regional transmission systems

confirm acceptance

Examples of GRID Indiscipline

Switching off of ISTS element without permission of RLDC (except under emergency)

inadequately qualified & untrained trained personnelIn control centers

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 load by more than one hundred (100 MW) (20 MW in case of North-Eastern region)

Not ensuring/ providing of RTU and othercommunicationequipment for sendingreal-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 equipment within the specified fault clearance time with reliability, selectivity and sensitivity

CONCLUSIO

N