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SOUTHERN REGIONAL LOAD DESPATCH CENTERPOSOCO, POWERGRID, BANGALORE

Indian Electricity Grid Code 2010

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INDIAN ELECTRICITY GRID CODE 2010

Applicable w.e.f. 3rd May,2010

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IEGC - INTRODUCTION

The Indian Electricity Grid Code (IEGC) is

a regulation made by the Central Commission in

exercise of powers under clause (h) of subsection (1)of Section 79 read with clause (g) of sub-section (2)of Section 178 of the Act.

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What is IEGC ?

A Set of rules, guidelines and standards

to be followed by various persons and

participants in the system

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

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INDIAN ELECTRICITY GRID CODE 2010

IEGC Feb 2000

IEGC Mar 2002

IEGC April 2006

IEGC April 2009

IEGC April 2010

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OBJECTIVE of IEGC

The IEGC brings together a single set of technical and commercial rules,encompassing all the Utilities connected to/or using the inter-State transmissionsystem (ISTS) and provides the following:

Documentation of the principles and procedures which define the relationshipbetween the various Users of the inter-State transmission system (ISTS), NationalLoad Despatch Centre, as well as the Regional and State Load Despatch Centers

Facilitation of the optimal operation of the grid, facilitation of coordinated and optimalmaintenance planning of generation and transmission facilities in the grid andfacilitation of development and planning of economic and reliable National / RegionalGrid

Facilitation for functioning of power markets and ancillary services by defining a

common basis of operation of the ISTS, applicable to all the Users of the ISTS.

Facilitation of the development of renewable energy sources by specifying thetechnical and commercial aspects for integration of these resources into the grid

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Structure of IEGC

IEGC contains the following:

i) Part 2: Role of various Organizations and their linkages

This Part defines the functions of the various Organizations as arerelevant to IEGC.

ii) Part 3:Planning Code for inter-State transmission

This Part provides the guidelines to be adopted in the planning and

development of bulk power transfer and associated ISTS. The

Planning Code lays out the detailed information exchange required

between the planning agencies and the various participants of the

power system for load forecasting, generation availability, andpower system planning etc. for the future years under study. The

Planning Code stipulates the various criteria to be adopted during

the planning process

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Structure of IEGC

iii) Part 4: Connection CodeThis Part specifies minimum technical and design criteria to be

complied with by STU, CTU and any User connected to the system

or seeking connection to the ISTS, to maintain uniformity and

quality across the system. This also includes procedure forconnection to the ISTS

iv) Part 5: Operating CodeThis Part describes the operational philosophy to maintain efficient,

secure and reliable Grid Operation and contains the following

sections.

(a) Operating Philosophy

(b) System security aspectsThis section describes the general security aspects to be

followed by generating companies and all Regional Entities,

CTU, STU, and all other Users of the Grid.

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Structure of IEGC

(c) Demand Estimation for operational purposesThis section details the procedures to estimate the demand

by the SEB/distribution licensees for their systems / SLDCs

in their control area for the day/week/month/year ahead,

which shall be used for operational planning.

(d) Demand management

This section identifies the methodology to be adopted fordemand control by each SEB/SLDC/Distribution Licensee/

bulk consumer depending on, overdrawal by the entity,

frequency, voltage and transmission congestion. and any

other requirement of grid security.

(e) Periodic ReportsThis section provides various provisions for reporting of the

operating parameters of the grid such as frequency profile etc.

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Structure of IEGC

(f) Operational liaisonThis section sets out the requirement for the exchange of

information in relation to normal operation and/or events in

the grid.

(g) Outage Planning

This section indicates procedure for outage planning.(h) Recovery procedures

This section contains the procedures to be adopted following

a major grid disturbance, for black start and

resynchronization of islands, etc.

(i) Event InformationThis section indicates the procedure by which events are

reported and the related information exchange requirements

etc

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Structure of IEGC

v) Part 6: Scheduling and Despatch Code

This section deals with the procedure to be adopted for scheduling and Despatch ofgeneration of the Inter-State Generating Stations (ISGS) and scheduling for othertransactions through long-term access, medium-term and short-term open accessincluding complementary commercial mechanisms, on a day-ahead and intra-daybasis with the process of the flow of information between the ISGS, National LoadDespatch Centre (NLDC), Regional Load Despatch Centre (RLDC), Power Exchanges

and the State Load Despatch Centres (SLDCs), and other concerned persons .

Most of the wind and solar energy sources are presently connected and in future arelikely to be connected to the STU or the States distribution utility. However, keeping inview the variable nature of generation from such sources and the effect suchvariability has on the inter- state grid, and in view of the large-scale integration of suchsources into the grid envisaged in view of the Government of Indias thrust onrenewable sources of energy, scheduling of wind and solar energy sources has been

incorporated in this Code.

vi) Part 7: Miscellaneous

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Non -compliance of IEGC

(i) RLDCs shall report to the Commission instances of serious orrepeated violation of any of the provisions of the IEGC andincidences of persistent non-compliance of the directions of theRLDCs issued in order to exercise supervision and control requiredfor ensuring stability of grid operations and for achieving themaximum economy and efficiency in the operation of the powersystem in the region under its control.

(ii) The Regional Power Committee (RPC) in the region shall alsocontinuously monitor the instances of non-compliance of theprovisions of IEGC and try to sort out all operational issues anddeliberate on the ways in which such cases of non-compliance areprevented in future by building consensus. The Member SecretaryRPC may also report any issue that cannot be sorted out at theRPC forum to the Commission.The RPC shall also file monthlyreports on status of UI payment and installation of capacitors bystates vis--vis the requirement/targets, as decided in the RPC.

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Non -compliance of IEGC

(iii) The Commission may initiate appropriateproceedings upon receipt of report of RPCs or RLDCsreferred to in (i) and (ii) above respectively.

(iv) In case of non-compliance of any provisions of theIEGC by NLDC, RLDC, SLDC, RPC and any otherperson the matter may be reported by any person to theCERC through petition.

(v) Notwithstanding anything contained in theseregulations, the Commission, may also take suo-motuaction against any person, in case of non-compliance ofany of the provisions of the IEGC.

2 R l f SLDC

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2.7 Role of SLDC

SLDCs apex body for integrated grid operation within theState :

(a) optimum scheduling and despatch

(b) monitor grid operations;

(c) keep accounts of electricity

(d) supervision and control over the intra-Statetransmission system

(e) secure and economic real time operations as per theState Grid Code.

(f) achieve the maximum economy and efficiency(g) accord concurrence or NoC for Open access in ISTSinvolving a state utility

Every state entity to comply with the directions of SLDC

SLDC to comply with the directions of the RLDC

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2.8. Role of STU (2.8.1 Sec 39 of the Act, 2003

(1) (a) intra-State electricity transmission;

(b) ofplanning 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 systemof 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 orcorporation is notified by the State Government

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CONNECTION CODE

4.6.1 Reactive Power Compensationa) STU and users to provide Reactive Power

compensation and/or other facilities, close to theload points thereby avoiding the need for exchangeof Reactive Power to/from ISTS and to maintain ISTS

voltage within the specified range.

b) To provide additional reactive compensation as perRPC and RLDC

The Users and STUs shall provide information toRPC and RLDC regarding the installation andhealthiness of the reactive compensationequipment on regular basis.

RPC shall regularly monitor the status in this regard.

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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 byRLDC.

Establish data flow up to appropriate data collection point on CTUs system,

provide the required facilities at their respective ends as specified in theConnection Agreement

4.6.5 Cyber Security

All utilities shall have in place, a cyber security framework to identify thecritical cyber assets and protect them so as to support reliable operation ofthe grid.

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OPERATING CODE

All the users to5.1 (d) comply with the directions of RLDC /SLDC to ensure integrated

grid operation and for achieving the maximum economy and efficiency inthe operation of the power system.

5.1 (g) Develop a set of detailed operating procedures for each state gridin 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 allregional entities shall be manned round the clock by qualified andadequately trained personnel. Training requirements may be notified bythe 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 ofrestoration shall also be intimated. All reasonable attempts shall be madefor the elements restoration as soon as possible.

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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 reportedby SLDC to RLDC

Automatic Load disconnection (Demand side Management)

scheme shall be implemented by the State utilities before

01.01.2011

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Voltage Control

Generating units of above

50MW size shall have

AVRs (Automatic Voltage

Regulators) in operation

and PSS (Power SystemStabilizers) shall be got

properly tuned.

Operating Range of Voltage

Nominal Maximum Minimum

765 800 728

400 420 380

220 245 198132 145 122

110 121 99

66 72 60

33 36 30

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RGMO

FEATURES OF RGMO

When system freq is below 50.2Hz, any improvement infrequency 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 unitshall increase by 5% limited to 105% of MCR (maximumcontinuous Rating) subject to the Machine capability.

Ripple filter of +/- 0.03 Hz. shall be provided so that smallchanges in frequency are ignored for load correction, inorder to prevent governor hunting.

Clause

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RGMO

RGMO Shall be effective from the dates as below:

For Thermal Generating unit of 200MW & above

Software based Electro Hydraulic Governor System(EHG) -1.8.2010

Hardware based EHG system - 1.8.2010

For Hydro units of 10 MW & above - 1.8.2010

Clause

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System Protection Schemes

AUFR / df/dt Schemes:

SLDC shall furnish the details of load relief on operation of AUFRor df/dt to RLDC on real time basis.

RLDC shall report such instances to RPC where there wasno/inadequate response.

SLDC shall submit a monthly report to RPC in this regard

RLDC shall submit a comparative record of expected load reliefand actual load relief obtained in Real time system operation toRPC and CERC on monthly basis.

SPS (SPECIAL PROTECTION SCHEMES) Shall be identified,installed and commissioned to operate the transmission systemcloser to its limits and to protect the same against voltagecollapse, cascade tripping and tripping of important corridors /flow gates

Clause

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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 providedto 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.

Clause

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Demand side Management

Contingency Procedure that enable demand disconnection asinstructed by RLDC / SLDC under normal and / or contingentcondition

State Electricity Boards/Distribution Licensees shall alsoformulate and implement state-of-the-art demand managementschemes for automatic demand management like rotationalload shedding, demand response (which may include lowertariff for interruptible loads) etc. before 01.01.2011. A Reportdetailing the scheme and periodic reports on progress ofimplementation of the schemes shall be sent to the CentralCommission by the concerned SLDC.

Grouping of Loads by SLDC without overlapping betweendifferent 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 Schemeidentified at the RPC level.

Clause

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Communication System

Each User, STU, RLDC, NLDC and CTU shallprovide and maintain adequate and reliablecommunication facility internally and with other

Users / STUs / RLDC / SLDC to ensure exchangeof data / information necessary to maintainreliability and security of the grid.

Clause

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Restoration Procedure

RLDC shall develop detailed plans and procedures for restoration of theregional grid underpartial/total blackout and shall be reviewed / updated

annually.

b) Detailed plans and procedures for restoration after partial/total blackout

ofeach Users/STU/CTU system within a Region, will be finalized by the

concerned Users/STU/CTU in coordination with the RLDC. The procedurewill 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.

Clause

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Scheduling Responsibility

RLDC has Scheduling Responsibility for a) Central Generating Stations (excluding stations where full Share is

allocated to host state),

b) Ultra-Mega power projects

c) If a generating station is connected only to the ISTS, (except forCentral Generating Stations where full Share is allocated to one State)

d) If a generating station is connected to both ISTS and the Statenetwork and if the state has 50% Share of power or less ( of thegenerating capacity put into commercial operation)

SLDC has Scheduling Responsibility for

a) Generating station which is connected only to the State transmissionnetwork

b) Central Generating Station whose full Share is allocated to host state. c) If a generating station is connected both to ISTS and the State

network and if the state has more than 50% Share of power (of thegenerating capacity put into commercial operation)

d) Generating station supplying power to any state other than host state

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Scheduling Responsibility

NLDC shall be responsible for

scheduling and despatch of electricity over inter-regional links in

accordance with the grid code specified by Central Commission in

coordination with Regional Load Despatch Centers.

NLDC shall be responsible for coordination with Regional Load Despatch

Centers for the energy accounting of inter-regional exchange of power.

NLDC shall also be responsible for coordination for trans-national

exchange of power.

NLDC shall develop a procedure for scheduling of collective transaction

through Power Exchanges, scheduling of inter-regional power

exchanges including HVDC setting responsibility and power exchanges

of the country with other countries., ,

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Cont..

All concerned entities (in whose premises the special energymeters are installed) shall take weekly meter readings andtransmit them to the RLDC by Tuesday noon The SLDC mustensure that the meter data from all installations within theircontrol area are transmitted to the RLDC within the aboveschedule.

Deviations, if any, from the ex-power plant generationschedules / ex-boundary drawal schedule shall beappropriately priced in accordance with UI Regulations. Inaddition, deviations, from schedules causing congestion, shallalso be priced in accordance with the Congestion ChargeRegulations. of CERC

The operating log books of the generating station shall beavailable for review by the Regional Power Committee. Thesebooks shall keep record of machine operation andmaintenance.

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Revision of Schedule (LTOA & MTOA)

In the event of system constraint the RLDC shall suo-mottu revisethe schedules which shall become effective from the 4th timeblock. Also, during the first, second and third time blocks of suchan event, the scheduled generation of the ISGS shall be deemed

to have been revised to be equal to actual generation

Revision of declared capability by the ISGS(s) having two parttariff with capacity charge and energy charge (except hydrostations) and requisition by beneficiary(ies) for the remainingperiod of the day shall also be permitted with advance notice.

Revised schedules/declared capability in such cases shallbecome effective from the 6th time block,

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Revision of STOA on real time operation

Notwithstanding anything contained in Regulation 6.5(18), in caseof forced outage of a unit for a Short Term bilateral transaction,where a generator of capacity of 100 MW and above is seller, thegenerator shall immediately intimate the same along with therequisition for revision of schedule and estimated time ofrestoration of the unit, to SLDC/RLDC as the case may be. Withthe objective of not affecting the existing contracts, the revision of

schedule shall be with the consent of the buyer till 31.07.2010.

Thereafter , consent of the buyer shall not be a pre-requisite forsuch revision of schedule. The schedule of the generator and thebuyer shall be revised, accordingly. The revised schedules shallbecome effective from the 4th time block, counting the time block

in which the forced outage is declared to be the first one.. TheRLDC shall inform the revised schedule to the seller and thebuyer. The original schedule shall become effective from theestimated time of restoration of the unit. However thetransmission charges as per original schedule shall continue tobe paid for two days.

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Scheduling of Wind Generation

With effect from 1.1.2011 Scheduling of wind power generation

plants would have to be done for the purpose of UI where the

sum of generation capacity of such plants connected at the

connection point to the transmission or distribution system is 10

MW and above and connection point is 33 KV and above, and

where PPA has not yet been signed.

The schedule by wind power generating stations may be revised

by giving advance notice to SLDC/RLDC, as the case may be.

Such revisions by wind power generating stations shall be

effective from 6th time-block ,the first being the time block inwhich notice was given. There may be maximum of 8 revisions

for each 3 hour time slot starting from 00:00 hours during the day.

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5.2(u) Special requirements for Solar/ wind

generators

(u) Special requirements for Solar/ wind generatorsSystem operator (SLDC/ RLDC) shall make all efforts to evacuatethe available solar and wind power and treat as a must-run station.However, System operator may instruct the solar /wind generator toback down generation on consideration of grid security or safety ofany equipment or personnel is endangered and Solar/ wind

generator shall comply with the same. For this, Data AcquisitionSystem facility shall be provided for transfer of information toconcerned SLDC and RLDC

(i) SLDC/RLDC may direct a wind farm to curtail its VAr drawl/injectionin case the security of grid or safety of any equipment or personnelis endangered.

(ii) During the wind generator start-up, the wind generator shall ensurethat the reactive power drawl (inrush currents incase of inductiongenerators) shall not affect the grid performance.

23 S i l di ti f h d li

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23 . Special dispensation for scheduling

of wind and solar generation

i) With effect from 1.1.2011 Scheduling of Solar power

generation plants (5 MW and above and connection

point is 33 KV where PPA has not yet been signed)

In case of solar generation no UI shall be

payable/receivable by Generator.

ii) The schedule of solar generation shall be given by the

generator based on availability of the generator,

weather forecasting, solar insolation, season and

normal solar generation curve and shall be vetted bythe RLDC

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Reactive Power Management

The charge for VArh shall be at the rate of 10 paise/kVArh w.e.f.1.4.2010, and this will be applicable between the Regional Entity,except Generating Stations, and the regional pool account for VArinterchanges. This rate shall be escalated at 0.5paise/kVArh peryear thereafter, unless otherwise revised by the Commission.

In general, the Regional Entities except Generating Stations shallendeavor to minimize the VAr drawal at an interchange pointwhen the voltage at that point is below 95% of rated, and shall notreturn VAr when the voltage is above 105%. ICT taps at therespective drawal points may be changed to control the VArinterchange as per a Regional Entity except GeneratingStationss request to the RLDC, but only at reasonable intervals.

Switching in/out of all 400 kV bus and line Reactors throughoutthe grid shall be carried out as per instructions of RLDC. Tapchanging on all 400/220 kV ICTs shall also be done as perRLDCs instructions only.

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Other Important Features

Control Area Defined

Neighboring Country defined as a separate control area

Provision for reporting consistent Non-compliance of constituents to

CERC directly by RLDC

Functions of NLDC defined. NLDC shall supervise inter regional links

SLDCs shall also develop Operating Procedure for real time grid

operation.

Prolonged outage of power system elements shall be monitored byRLDC and report to RPC for suitable action.

Special exemption limit on UI volume for wind and other renewable

energy generation

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THANK YOU

Typical Graph Depict in g Pr ic ing of Unsch eduled Interchang es

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Incremental Cost(Paise/kWH)U

I

Price

S

tationGeneration

Pool Price

Typical Graph Depict in g Pric ing of Unsch eduled Interchang es

w .r.t . System Frequency

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CONNECTION CODE

4.6.2 Data and Communication FacilitiesReliable and efficient speech and data communication systems shall beprovided to facilitate necessary communication and data exchange, andsupervision/control of the grid by the RLDC, under normal and abnormalconditions. All Users, STUs and CTU shall provide Systems to telemeterpower 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. The associated communication system tofacilitate data flow up to appropriate data collection point on CTUs system,shall also be established by the concerned User or STU as specified byCTU in the Connection Agreement. All Users/STUs in coordination withCTU shall provide the required facilities at their respective ends as specifiedin the Connection Agreement

4.6.5 Cyber SecurityAll utilities shall have in place, a cyber security framework to identify thecritical cyber assets and protect them so as to support reliable operation ofthe grid.

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FGMO

5.2 (h) All thermal generating units of 200 MW and above and allhydro units of 10 MW and above operating at or up to 100% oftheir Maximum Continuous Rating (MCR) shall normally becapable of (and shall not in any way be prevented from)instantaneously picking up to 105% and 110% of their MCR ,respectively, when frequency falls suddenly. After an increase in

generation as above, a generating unit may ramp back to theoriginal level at a rate of about one percent (1%) per minute, incase continued operation at the increased level is notsustainable. Any generating unit not complying with the aboverequirements, shall be kept in operation (synchronized with theRegional grid) only after obtaining the permission of RLDC.

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FGMO

5.2 (i) The recommended rate for changing the governor setting, i.e.,supplementary control for increasing or decreasing the output(generation level) for all generating units, irrespective of their typeand size, would be one (1.0) per cent per minute or as permanufacturers limits. However, if frequency falls below 49.7Hz,all partly loaded generating units shall pick up additional load at a

faster rate, according to their capability.

5.2 (j) Except under an emergency, or to prevent an imminentdamage to a costly equipment, no User shall suddenly reduce hisgenerating unit output by more than one hundred (100) MW ( 20MW in case of NER) without prior intimation to and consent of the

RLDC, particularly when frequency is falling or is below 49.5 Hz..Similarly, no User / SEB shall cause a sudden variation in its loadby more than one hundred (100 MW) without prior intimation toand consent of the RLDC.

Automatic voltage regulators

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Automatic voltage regulators

(AVRs)

5.2 (k) All generating units shall normally have theirautomatic voltage regulators (AVRs) in operation. Inparticular, if a generating unit of over fifty (50) MW sizeis required to be operated without its AVR in service,

the RLDC shall be immediately intimated about thereason and duration, and its permission obtained.Power System Stabilizers (PSS) in AVRs ofgenerating units (wherever provided), shall be gotproperly tuned by the respective generating unit owner

as per a plan prepared for the purpose by theCTU/RPC from time to time. CTU /RPC will be allowedto carry out checking of PSS and further tuning it,wherever considered necessary.

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Frequency Control

5.2 (m) All Users, SEB,, SLDCs , RLDCs, and NLDC shall take all possiblemeasures to ensure that the grid frequency always remains within the49.550.2 Hz band.

(n) All SEBS, distribution licensees / STUs shall provide automatic under-

frequency and df/dt relays for load shedding in their respective systems,to arrest frequency decline that could result in a collapse/disintegrationof the grid, as per the plan separately finalized by the concerned RPCand shall ensure its effective application to prevent cascade tripping ofgenerating units in case of any contingency. All , SEBs, distributionlicensees, CTU STUs and SLDCs shall ensure that the above under-

frequency and df/dt load shedding/islanding schemes are alwaysfunctional. RLDC shall inform RPC Secretariat about instances when thedesired load relief is not obtained through these relays in real timeoperation. The provisions regarding under frequency and df/dt relays ofrelevant CEA Regulations shall be complied with. SLDC shall furnishmonthly report of UFR and df/dt relay operation in their respective

system to the respective RPC.

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5.2.(o) All Users, STU/SLDC , CTU/RLDC and NLDC, shall

also facilitate identification, installation and

commissioning ofSystem Protection Schemes (SPS)

(including inter-tripping and run-back) in the power

system to operate the transmission system closer to theirlimits and to protect against situations such as voltage

collapse and cascade tripping, tripping of important

corridors/flow-gates etc.. Such schemes would be

finalized by the concerned RPC forum, and shall alwaysbe kept in service.If any SPS is to be taken out of

service, permission of RLDC shall be obtained indicating

reason and duration of anticipated outage from service .

Frequency Control

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Trip Analysis

5.2 (r) All the Users , STU/SLDC and CTU

shall send information/data including

disturbance recorder/sequential event

recorder output to RLDC within oneweek for purpose of analysis of any grid

disturbance /event. No User,SLDC /STU

or CTU shall block any data/informationrequired by the RLDC and RPC for

maintaining reliability and security of the

grid and for analysis of an event.

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Voltage Control

5.2 (s) All Users, RLDC,

SLDC STUs , CTU and

NLDC shall take all

possible measures to

ensure that the gridvoltage always remains

within the following

operating range.

Voltage (kV rms)

Nominal Maximum Minimum

765 800 728

400 420 380

220 245 198

132 145 122

110 121 99

66 72 60

33 36 30

2( ) S i l i f S l / i d

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5.2(u) Special requirements for Solar/ wind

generators

(u) Special requirements for Solar/ wind generatorsSystem operator (SLDC/ RLDC) shall make all efforts to evacuatethe available solar and wind power and treat as a must-run station.However, System operator may instruct the solar /wind generator toback down generation on consideration of grid security or safety ofany equipment or personnel is endangered and Solar/ wind

generator shall comply with the same. For this, Data AcquisitionSystem facility shall be provided for transfer of information toconcerned SLDC and RLDC

(i) SLDC/RLDC may direct a wind farm to curtail its VAr drawl/injectionin case the security of grid or safety of any equipment or personnelis endangered.

(ii) During the wind generator start-up, the wind generator shall ensurethat the reactive power drawl (inrush currents incase of inductiongenerators) shall not affect the grid performance.

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5.3 Demand Estimation for

Operational Purposes

(a) This section describes the procedures/

responsibilities of the SLDCs for demand

estimation for both Active Power and

Reactive Power.

(b) The demand estimation is to be done

on daily /weekly/monthly /yearly basis for

current year for load - generationbalance planning. The SLDC shall carry

out system studies for operational

planning purposes using this demand

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(c) Each SLDC shall develop methodologies/mechanisms for daily/weekly/monthly/yearly demand estimation (MW, MVAr and MWh) foroperational purposes. Based on this demand estimate and the estimatedavailability from different sources,

SLDC shall plan demand management measures like load shedding, powercuts, etc. and shall ensure that the same is implemented by theSEB/distribution licensees. SLDCs. All SEBs/distribution licensees shallabide by the demand management measures of the SLDCs and shallalso maintain historical database for demand estimation.

(d) Each SLDC shall carry out its own demand estimation from thehistorical data and weather forecast data from time to time. Alldistribution licensees and other concerned persons shall providerelevant data and other information as required by SLDC for demandestimate.

5.3 Demand Estimation for Operational

Purposes

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(e) While the demand estimation for operational purposes is to be doneon a daily/ weekly/monthly basis initially, mechanisms and facilitiesat SLDCs shall be created at the earliest but not later than 1.1.2011to facilitate on-line estimation of demand for daily operational use foreach 15 minutes block.

(f) The monthly estimated demand by the SLDC shall be provided toRLDC and RPC for better operation planning

g) The SLDC shall take into account the Wind Energy forecasting tomeet the active and reactive power requirement.

(h) In order to facilitate estimation of Total Transfer Capability/Available Transfer Capability on three month ahead basis , theSLDC shall furnish estimated demand and availability data toRLDCs.

5.3 Demand Estimation for

Operational Purposes

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5.4.2 Demand Disconnection

(a) SLDC/ SEB/distribution licensee and bulk consumer shall initiateaction to restrict the drawal of its control area ,from the grid, withinthe net drawal schedule whenever the system frequency falls to49.7 Hz

(b) The SLDC/ SEB/distribution licensee and bulk consumer shallensure that requisite load shedding is carried out in its control areaso that there is no overdrawl when frequency is 49.5 Hz. or below.

c) Each User/STU/SLDC shall formulate contingency procedures andmake arrangements that will enable demand disconnection to takeplace, as instructed by the RLDC/SLDC, under normal and/orcontingent conditions. These contingency procedures andarrangements shall regularly be / updated by User/STU andmonitored by RLDC/SLDC. RLDC/SLDC may direct any User/STUto modify the above procedures/arrangement, if required, in theinterest of grid security and the concerned User/STU shall abide bythese directions.

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d) The SLDC through respective State Electricity Boards/ DistributionLicensees shall also formulate and implement state-of-the-art demandmanagement schemes forautomatic demand management like rotationalload shedding, demand response (which may include lower tariff forinterruptible loads) etc. before 01.01.2011, to reduce overdrawl in order tocomply para 5.4.2 (a) and (b) . A Report detailing the scheme and periodicreports on progress of implementation of the schemes shall be sent to the

Central Commission by the concerned SLDC.

e) In order to maintain the frequency within the stipulated band and maintainingthe network security, the interruptible loads shall be arranged in four groupsof loads, for scheduled power cuts/load shedding, loads for unscheduledload shedding, loads to be shed through under frequency relays/ df/dtrelays and loads to be shed under any System Protection Scheme identified

at the RPC level. These loads shall be grouped in such a manner , thatthere is no overlapping between different Groups of loads. In case of certaincontingencies and/or threat to system security, the RLDC may direct anySLDC/ SEB/ distribution licensee or bulk consumer connected to the ISTSto decrease drawal of its control area by a certain quantum. Such directionsshall immediately be acted upon. SLDC shall send compliance reportimmediately after compliance of these directions to RLDC.


5 4 2 D d Di ti

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f) To comply with the direction of RLDC, SLDC may direct

any SEB/ distribution licensee/bulk consumer connected

to the STU to curtail drawal from grid. SLDC shall

monitor the action taken by the concerned entity and

ensure the reduction of drawal from the grid as directed

by RLDC.

g) RLDCs shall devise standard, instantaneous, message

formats in order to give directions in case of

contingencies and /or threat to the system security to

reduce overdrawl by the bulk consumer , SLDC/ State atdifferent overdrawal conditions depending upon the

severity of the overdrawal. The concerned SLDC shall

ensure immediate compliance with these directions of

RLDC and send a compliance report to the concernedRLDC.


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h) All Users, SLDC/ SEB/distribution licensee or bulk consumer shallcomply with direction of RLDC/SLDC and carry out requisite loadshedding or backing down of generation in case of congestion intransmission system to ensure safety and reliability of the system.The procedure for application of measures to relieve congestion inreal time as well as provisions of withdrawl of congestion shall be in

accordance with Central Electricity Regulatory Commission(Measures to relieve congestion in real time operation) Regulations,2009

i) The measures taken by the Users, SLDC SEB/ distribution licenseeor bulk consumer shall not be withdrawn as long as the frequencyremains at a level lower than the limits specified in para 5.2 orcongestion continues, unless specifically permitted by the RLDC/SLDC.


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6.4 Demarcation of responsibilities:

2. The following generating stations shall come under the respectiveRegional ISTS control area and hence the respective RLDC shallcoordinate the scheduling of the following generating stations :

a) Central Generating Stations (excluding stations where full Share isallocated to host state),

b) Ultra-Mega power projects(c) In other cases, the control area shall be decided on the following

criteria:

(i) If a generating station is connected only to the ISTS, RLDC shallcoordinate the scheduling, except for Central Generating Stationswhere full Share is allocated to one State.

(ii) If a generating station is connected only to the State transmissionnetwork, the SLDC shall coordinate scheduling, except for the caseas at (a) above.

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(iii) If a generating station is connected both to ISTS and the State network,scheduling and other functions performed by the system operator of acontrol area will be done by SLDC,, only .if state has more than 50%Share of power ,The role of concerned RLDC, in such a case, shall belimited to consideration of the schedule for inter state exchange ofpower on account of this ISGS while determining the net drawalschedules of the respective states. If the State has a Share of 50% or

less, the scheduling and other functions shall be performed by RLDC.

(iv) In case commissioning of a plant is done in stages the decisionregarding scheduling and other functions performed by the systemoperator of a control area would be taken on the basis of above criteriadepending on generating capacity put into commercial operation at that

point of time. Therefore it could happen that the plant may be in onecontrol area (i.e. SLDC) at one point of time and another control area(i.e. RLDC) at another point of time. The switch over of control areawould be done expeditiously after the change, w.e.f. the next billingperiod.

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.4 Demarcation of responsibilities:

7. The SLDC, SEB/distribution licensee shall always endeavour torestrict the net drawal of the state from the grid to within thedrawal schedules, whenever the system frequency is below49.7 Hz. The concerned SEB/distribution licensee User,SLDCshall ensure that their automatic demand management schemementioned in clause 5.4.2 acts to ensure that there is no overdrawl when frequency is 49.5 Hz or below. If the automaticdemand management scheme has not yet been commissioned,then action has to be taken as per manual demandmanagement scheme to ensure zero overdrawal whenfrequency r is 49.5 Hz. or below.

8. The SLDCs/STUs /Distrbution Licensees shall regularly carry outthe necessary exercises regarding short-term demandestimation for their respective States/area, to enable them toplan in advance as to how they would meet their consumersload without overdrawing from the grid.

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12. However, notwithstanding the above, the RLDC may direct theSLDCs/ISGS/other regional entities to increase/decrease theirdrawal/generation in case of contingencies e.g. overloading oflines/transformers, abnormal voltages, threat to system security. Suchdirections shall immediately be acted upon. In case the situation does notcall for very urgent action, and RLDC has some time for analysis, it shallbe checked whether the situation has arisen due to deviations from

schedules, pursuant to short-term open access. These shall be gotterminated first, before an action, which would affect the scheduledsupplies to the long term and medium term customers is initiated inaccordance with Central Electricity Regulatory Commission (Grant ofConnectivity, Long-term Access and Medium-term Open Access in inter-state Transmission and related matters) Regulations,2009.

15. All other regional entities should abide by the concept offrequency-linked load despatch and pricing of deviations from schedule, i.e.,unscheduled interchanges. All regional entities should normally beoperated according to the standing frequency-linked load despatchguidelines issued by the RLDC, to the extent possible, unless otherwiseadvised by the RLDC/SLDC.


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21. All concerned entities (in whose

premises the special energy meters are

installed) shall take weekly meter

readings and transmit them to the RLDCby Tuesday noon The SLDC must

ensure that the meter data from all

installations within their control area aretransmitted to the RLDC within the above

schedule.

6.4 Demarcation of responsibilities

6.5 Scheduling and Despatch

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6.5 Scheduling and Despatch

procedure

18. Revision of declared capability by the ISGS(s) having

two part tariff with capacity charge and energy

charge(except hydro stations) and requisition by

beneficiary(ies) for the remaining period of the day

shall also be permitted with advance notice. Revisedschedules/declared capability in such cases shall

become effective from the 6th time block, counting

the time block in which the request for revision has

been received in the RLDC to be the first one.

Revision on Forced Outage of

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Revision on Forced Outage of

Gen unit

a new subclause,namely, 6.5.18(a) shall be added asunder:

6.5.18(a). Notwithstanding anything contained inRegulation 6.5.18, in case of forced outages of a unit,

for those stations who have a two part tariff based oncapacity charge and energy charge for long term andmedium term contracts, the RLDC shall revise theschedule on the basis of revised declared capability.The revised declared capability and the revised

schedules shall become effective from the fourth timeblock, counting the time block in which the revision isadvised by the ISGS to be the first one.

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iegc 2010 20042011_20apr-11 (2)

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