Shabari Pramanick

Deputy Manager,ERLDC

POSOCO

Indian Electricity Grid Code

All Users, SLDCs, RLDCs, NLDC, CEA, CTU, STUs, Licensees, RPCs, PXs

Vertically integrated agencies like DVC shall be treated like SEBs- DVC has its own generation , transmission , distribution & LDC at Maithon

BBMB, NCA to be treated as ISGS- Generation is scheduled & despatched in a special manner(in coordination

with irrigational requirements)

- Scheduling & Despatch of SSP

o NCA in coordination with WRLDC

o BBMB in coordination with NRLDC

Any neighbouring country interconnected with Indian Grid- to be treated as a separate control area

Part 1: General

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Scope of IEGC

Compliance Oversight (1.5)

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CERC

Repeated Violation/Persistent Non Compliance

RLDC

Report

RPC Forum ConsensusReport issues not sorted

suo-motto

Direction/Order

Compliance Oversight (1.5)….

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Non Compliance by NLDC, RLDC, SLDC, RPC or any other person

Direction/Order

Report by anypersonthrough

petition

CERC

Section 2.2: NLDC

Section 2.3: RLDC

Section 2.4: RPC

Section 2.5: CTU

Section 2.6: CEA

Section 2.7: SLDC

Section 2.8: STU

Part 2. Role of various Organizations & Linkages

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Section 3.1: Introduction

Section 3.2: Objective

Section 3.3: Scope

Section 3.4: Planning Philosophy

Section 3.5: Planning Criterion

Section 3.6: Planning Data

Section 3.7: Implementation of Transmission Plan

Part 3. Planning Code for Inter-state Transmission

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Objectives and Scope of planning code (3.2 &3.3)

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ISTS

SEBsSTULicensees

ISGS GC

IPP

CTU

Generation/Transmission of

energy to/from ISTS

Connected to/using/developing ISTS

• specify principles,• specify procedures •specify criteria•promote coordination•information exchange

ObjectiveScope

Part - 4. Connection Code

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Minimum technical & design criteria

OBJECTIVE• Ensure the safe operation, integrity and reliability of the grid •Non-discriminatory•New/modified connection not to suffer or impose unacceptable effects on existing system•In advance knowledge about Connectivity

ISTS

SCOPE

CTUSTU

Any User connected to ISTS or seeking connection to ISTS

Any user/entity seeking connectivity to the grid shall comply to

1. CEA(Tech. standards of connectivity) Regulation- 2007

2. CERC (Grant of Connectivity, LTA & MTOA in ISTS) Regulation-

2009 & subsequent amendments

Reactive Power Compensation (4.6.1)- By /STUs and Users in the low voltage systems close to the load points

thereby avoiding exchange of reactive power to/ from the ISTS- Already connected users shall provide additional reactive compensation as

per the quantum and time frame decided by the RPC in consultation with RLDC.

- Installation and healthiness would be monitored by RPC

Data and Communication Facilities (4.6.2)- reliable and efficient speech and communication system to be provided - Users/STU/CTU shall provide systems to telemeter power system

parameterso Power Flowo Voltageo Status of switcheso Status of transformer taps

- Associated communication system to facilitate data flow up to appropriate data collection point on CTU’s system as specified by CTU in the Connection Agreement

Important Technical Requirements for Connectivity (4.6)

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System Recording Instruments (4.6.3)- Data Acquisition System/Disturbance Recorder/Event Logging

facilities/Fault Locator (including time synchronization equipment ) shall be provided and always kept in working condition

Responsibility for safety (4.6.4)

By complying with -

– CEA (Technical Standards for connectivity to the Grid), Regulations 2007

– CERC (Grant of Connectivity, LTA and MTOA in ISTS and related matters) Regulations 2009

– CEA (Safety Requirements for construction, operation and maintenance of electrical and electric lines) Regulations, 2008

International Connections to ISTS (4.7)- By CTU in consultation with CEA and MOP

Other connection codes

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Part-5 Operating code

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Objective of integrated operation:- enhance overall operational reliability and economy- Cooperate and adopt Good Utility Practice

NLDC:- overall operation of National/Inter-Regional Grid- develop/maintain detailed internal operating procedures for

national grid

RLDC:- overall operation of Regional Grid- develop/maintain detailed internal operating procedures for

regional grid

Operating philosophy (5.1)

SLDC:- overall operation of State Grid- develop/maintain detailed internal operating procedures for

State grid

All licensee, generating company, generating station and any other concerned person:

- To comply with directions of RLDC/SLDC

Round-the clock manning by qualified and trained personnel of:

- control rooms of NLDC, RLDC, SLDC, Power Plant, Sub Stations (132 kV & above)

- control centers of all regional constituents

Operating philosophy (5.1)

Maintain synchronism:- all Users, CTU & STU - operate their power systems/stations in an integrated

manner

No deliberate isolation of part of the grid, except:- under emergency- safety of human being/equipment- when instructed by RLDCRestoration to be supervised by RLDC in coordination with NLDC/SLDC

System Security Aspects (5.2)

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Important elements of the grid:- list of important elements to be prepared and shall be put

on website of NLDC/RLDC/SLDC- Any emergency removal to be intimated to RLDC- tripping, reason, likely time of restoration intimated to

RLDC say within 10 minutes- Prolonged outage ------ sub-optimal operation----monitored

by RLDC------report to RPC-------- finalize action plan for restoration

System Security Aspects (5.2)

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Following categories of units to be under RGMO/FGMO with manual intervention

- Coal/lignite based thermal unit of 200 MW and above

- Open cycle GT/Combined Cycle based thermal unit of 50 MW and above

- Hydro units of 25 MW and above

o Having pondage more than three hours

Droop characteristics between 3% and 6%

Ripple filter +/- 0.03 Hz

No reduction in unit output for increase in frequency up to 50 Hz (restricted mode operation)

For disabling governor influence, RLDC code is required

Generator Governor Action (5.2(f))

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Maximum RGMO/FGMO influence- Thermal generator 105% of initial generation up to 105% of MCR

- Hydro generator

o 105% of initial generation up to 105% of MCR

o 110% of MCR for sudden change in frequency

After increase in generation, ramping down ≤1% per minute

Technical Specification of RGMO/FGMO (5.2(f) & (h))

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(j) Sudden change in Generation or load > 100 MW not permitted, without intimation to and prior consent of RLDC.

Voltage to be within the limit

(k) AVR to be in service for generating units > 50 MWPSS to be properly tuned

(l) All SEBs, distribution licensees, CTU STUs and SLDCs shall ensure that under-frequency and df/dt load shedding / islanding schemes are always functional..

(m)System Protection Schemes (SPS) to operate the transmission system closer to its limit

(n) All the Users, STU/SLDC and CTU shall send information / data including disturbance recorder / sequential event recorder output to RLDC within one week for purpose of analysis of any grid disturbance/event.

System Security Aspects (5.2 ) contd.

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Allowable range of operating frequency

Sl. No. Period Allowable Operating Range

1 Till 31.03.2009 49.0-50.5 Hz.

2 01.04.2009-02.05.2012 49.2-50.3 Hz.

3 03.05.2012-13.09.2012 49.5-50.2 Hz.

4 14.09.2012-16.02.2014 49.7-50.2 Hz.

5 From 17.02.2014 49.9-50.05 Hz.

19Range narrowed down from 1.5 Hz to 0.15 Hz

Demand Estimation for Operational Purposes (5.3)

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on-line estimation

for daily operational

use

historical data

and weather forecast

Daily

/Weekly

/Monthly

Demand Estimation: –

Active and reactive

power

Inform to RLDC/RPC

Wind Energy Forecast

ATC/TTC

Online estimation of demand for each 15 min block

This section is concerned with the provisions to be made by SLDCs to effect a reduction of demand in the event of insufficient generating capacity, and inadequate transfers from external interconnections to meet demand, or in the event of breakdown or congestion in intra-state or inter-state transmission system or other operating problems (such as frequency, voltage levels beyond normal operating limit, or thermal overloads , etc. )

Demand Management(5.4)

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SLDC/ SEB/distribution licensee and bulk consumer shall initiate action to restrict the drawal of its control area ,from the grid, within the net drawal schedule

The SLDC/ SEB/distribution licensee and bulk consumer shall ensure that requisite load shedding is carried out in its control area so that there is no overdrawl

Each User/STU/SLDC shall formulate contingency procedures and make arrangements that will enable demand disconnection to take place, as instructed by the RLDC/SLDC

The SLDC through respective 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.

Demand Disconnection(5.4.2)

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weekly report by NLDC (put on website) (5.5.1 (a)):- Performance of national/integrated grid

daily report by RLDC (put on website) (5.5.1 (b)):- Performance of national/integrated grid- Wind power injection

weekly report by RLDC (put on website) (5.5.1 (c)): - Frequency and voltage profiles- Major generation & transmission outages- Transmission constraints- Instances of persistent/significant non-compliance of IEGC- Instances of congestion- Instance of inordinate delay in restoration - Non-compliance of instructions of SLDCs by SEB/Discom

quarterly report by RLDC (5.5.2 (a)):- system constraints, reasons for not meeting the requirements, security standards & quality of

service- actions taken by different persons- persons responsible for causing the constraints

RLDC shall provide information/report to RPC for smooth operation of ISTS (5.5.2 (b))

Periodic Reports (5.5)

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Outage Planning Process (5.7)

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MarJanNov next financial year

proposed outage programs by all concerned (30th Nov) (LGBR)

Dec

draft outage programme by RPC Secretariat (31st Dec) (LGBR)

final outage programme by (31st Jan)

Feb

Review by RPC Secretariat:adjustments made whereverfound to be necessary incoordination with all partiesconcerned

monthly review quarterly review

In consultation with NLDC/RLDC

In Emergency – RLDCs may conduct studies before clearance

NLDC/RLDC are authorized to defer the planned outage:- grid disturbance- system isolation- partial black out in a state- any other critical event

Latest detailed outage plan – updated

Each user, CTU and STU shall obtain one final approval from RLDC

RPC shall submit quarterly, half yearly reports to CERC indicating deviations

Outage Planning (5.7.4)

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Recovery Procedures (5.8)

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26

Detailed plans/procedures for restoration of partial/total blackout regional grid

consultations

RLDC

Concerned Constituents

RPC secretariat

develops

reviewed/updated annually

Detailed plans/procedures for restoration of respective systems from partial/total blackout

develop

reviewed/updated annually

• Mock trials once

every 6 months

•DG sets to be tested

on weekly basis-

quarterly report to be

sent to RLDC

Recovery Procedures (5.8) contd.

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List of following information shall be available withNLDC/RLDC/SLDC:

- generating stations with black start facility- inter-state/regional ties- synchronising points- essential loads to be restored on priority

During restoration following blackout, RLDCauthorized to operate the grid with reduced securitystandards for voltage & frequency

All communication channels for restoration shall beused for operational communications only till gridnormalcy is restored

Introduction- Reporting procedures in respect of events to all Users,

STU,CTU RPC secretariat, NLDC/RLDC/ SLDC

Responsibility- RLDC/SLDC shall be responsible for reporting events to the

Users/SLDC/ STU/CTU RPC secretariat/ NLDC /RLDC

- Users/ STU/CTU /SLDC shall be responsible for collection andreporting all necessary data to NLDC/RLDC and RPC secretariatfor monitoring, reporting, and event analysis

Event Information (5.9)

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Reportable events (5.9.5)

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i Violation of security Standards

ii Grid indiscipline

iii Non-Compliance of RLDC’s instruction

iv System islanding/ system split

v Regional black out/partial system black

out

vi Protection failure

vii Power system instability

viii Tripping of any element

ix Sudden load rejection by any user

Part-6 Scheduling & Despatch code

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Demarcation of responsibilitiesNLDC (6.4.26)

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NLDCTrans-National Exhange of Power

Scheduling on Inter Regional Links .

Energy accounting on IR Links- with RLDC

HVDC Settings

Scheduling of Inter-Regional Power Exchanges

Collective Transaction Scheduling

Ancillary Service Despatch and Scheduling (RRAS)

Demarcation of responsibilitiesRLDC (6.4)

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RLDC

Scheduling of CGS (Except where full share is allocated to host state)

Scheduling of UMPP incl. projects based on wind and solar having capacity > 500 MW

Scheduling of GS

connected to ISTS

Scheduling of GS connected both to ISTS and state grid and home state is less then 50%

Demarcation of responsibilitiesSLDC (6.4.5)

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SLDC

Permitting Open Access

Regulating net drawal (as per schedule)

Scheduling and dispatching (within own control area)

Scheduling drawalfrom ISGS (within net entitlement)

Demand RegulationImplementation ofADMS to ensure thereshall be no over drawl

6.4.8 Demand Estimationin coordination withSTU/Discoms and SLDC tosubmit to RLDC on dailybasis

Role of ISGS/ Generating Station (6.4.9)

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ISGS

Generate as per despatch schedule advised to them by RLDC

Minimize Deviation from Schedule (UI)

Proper Operation and Maintenance

BackdowngenerationWhen F>50.05Hz

Submit Outage plan in OCC of RPC

DC during Peak Hours > Other Hours

Declare DC

Role of CTU (6.4.21)

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CTU

Install SEMs at ISTS metering points

CEA (Installation and operation of Meters ) Regulations

Weekly Readings to RLDC by Tuesday – by all entities

SEMs located at periphery of constituents

36

Day-ahead Scheduling Procedure - Regulation 6.5

12 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1noon

ISGS

SLDC

AM PM

RLDC

Despatch

schedule

starts

Drawal

schedule

starts

final

Despatch

schedule

final

Drawal

schedule

09:45

NLDC

Network monitoring & control actions

RLDC may direct the SLDCs/ISGS/other regional entities

to increase/decrease their drawal/generation in case of

contingencies e.g. overloading of lines/transformers,

abnormal voltages, threat to system security. Such

directions shall immediately be acted upon.

In case the situation does not call for very urgent action,

and RLDC has some time for analysis, it shall be checked

whether the situation has arisen due to deviations from

schedules,

37

Network monitoring & control actions

These ( Deviations) shall be got terminated first, through

appropriate measure like opening of feeders, if

considered necessary by SLDC/RLDC, before an action,

which would affect the scheduled supplies to the long term

and medium term customers or short-term customers, is

initiated in accordance with Central Electricity Regulatory

Commission Open Access Regulations.

In case short term /Medium term or Long Term open

access are curtailed, RLDC(s) shall submit a report

regarding the reasons due to which it was not able to

curtail deviations from Schedule and agencies which

had not taken necessary actions. ( 2nd IEGC Amendment)

38

Inj. Schedule- Deviation by Hydro Gen.

Hydro generating stations are expected to respond to

grid frequency changes and inflow fluctuations.

Maximum deviation allowed during a time block

shall as per CERC Deviation Settlement

Mechanism regulations . ( 2nd IEGC Amendment).

39

Inj. Schedule- Deviation by Hydro Gen.

The schedule finalized by the concerned load despatch

centre for hydro generating station, shall normally be

such that the scheduled energy for a day equals the total

energy (ex-bus) expected to be available on that day, as

declared by the generating station, based on

foreseen/planned water availability/release.

It is also expected that the total net energy actually

supplied by the generating station on that day would

equal the declared total energy, in order that the water

release requirement is met.

( 2nd IEGC Amendment).

40

Special provisions for grid constraints (6.5.16)

In the event of bottleneck in evacuation of power due to anyconstraint, outage, failure or limitation in the transmission system,associated switchyard and substations owned by the CentralTransmission Utility or any other transmission licensee involvedin inter-state transmission (as certified by the RLDC) necessitatingreduction in generation, the RLDC shall revise the scheduleswhich shall become effective from the 4th time block, countingthe time block in which the bottleneck in evacuation of power hastaken place to be the first one.

Also, during the first, second and third time blocks of such anevent, the scheduled generation of the ISGS shall be deemed tohave been revised to be equal to actual generation, and thescheduled drawals of the beneficiaries shall be deemed to havebeen revised accordingly.

41

Special provisions for grid Constraints

If, at any point of time, the RLDC observes that there is need

for revision of the schedules in the interest of better system

operation, it may do so on its own, and in such cases, the

revised schedules shall become effective from the 4th time

block.

When for the reason of transmission constraints e.g. congestion

or in the interest of grid security, it becomes necessary to

curtail power flow on a transmission corridor, the transactions

already scheduled may be curtailed by the Regional Load

Despatch Centre. The short-term customer shall be curtailed

first followed by the medium-term customers, which shall be

followed by the long-term customers and amongst the

customers of a particular category, curtailment shall be carried

out on pro rata basis. 42

Special provisions for grid Disturbance In case of any grid disturbance, scheduled generation of all the

ISGSs supplying power under long/medium /short term shall

be deemed to have been revised to be equal to their actual

generation and scheduled drawal of all the beneficiaries / buyers

shall be deemed to be revised accordingly, for all the time

blocks affected by the grid disturbance. Certification of grid

disturbance and its duration shall be done by the RLDC.

The declaration of disturbance shall be done by the concerned

RLDC at the earliest. A notice to this effect shall be posted at

its website by the RLDC of the region in which the

disturbance occurred. Issue of the notice at RLDC web site

shall be considered as declaration of the disturbance by

RLDC. All regional entities shall take note of the disturbance

and take appropriate action at their end. ( 2nd IEGC

Amendment) 43

Special provisions for ISGS(s) having two part tariff (6.5.18)

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. Revised schedules/declared capability in

such cases shall become effective from the 4th time block .

44

Special provisions for Forced outage of ISGS(s) having two part tariff

Notwithstanding anything contained in Regulation 6.5.18, in

case of forced outages of a unit, for those stations who have a

two part tariff based on capacity charge and energy charge for

long term and medium term contracts, the RLDC shall revise

the schedule on the basis of revised declared capability.

The revised declared capability and the revised schedules

shall become effective from the fourth time block, counting

the time block in which the revision is advised by the ISGS to

be the first one.”

45

Special provisions for renewable

Since variation of generation in run-of-river power

stations shall lead to spillage, these shall be treated as

must run stations. All renewable energy power plants,

except for biomass power plants, , and non-fossil fuel

based cogeneration plants whose tariff is determined by

the CERC shall be treated as ‘MUST RUN’ power plants

and shall not be subjected to ‘merit order despatch’

principles.

46

Wind generation Scheduling

With effect from 1.1.2011 15.07.2013 Scheduling of Wind Gen.necessary:

i) where the sum of generation capacity of such plants connected atthe connection point to the transmission or distribution system is 10MW and aboveii) and connection point is 33 KV and above,iii) and where pooling stations commissioned after 03.05.2010 andwhere PPA has not yet been signed. (2nd Amend)

For capacity and voltage level below this, as well as for old windfarms ( A wind farm is collection of wind turbine generators thatare connected to a common connection point) it could be mutuallydecided between the Wind Generator and the transmission ordistribution utility, as the case may be, if there is no existingcontractual agreement to the contrary .

There may be maximum of 16 revisions starting from 00:00 hoursduring the day.

47

Scheduling of solar generation Scheduling necessary with effect from 1.7.2011, for newsolar generating plants with capacity of 5 MW andabove connected at connection point of 33 KV leveland above and , where pooling stationscommissioned after 03.05.2010 and where PPA hasnot yet been signed. (2nd Amend,)

Schedule to be given by the generator based onavailability of the generator, weather forecasting, solarinsolation, season and normal solar generation curve

to be vetted by the RLDC in which the generator islocated and incorporated in the inter-state schedule.

If RLDC is of the opinion that the schedule is notrealistic , it may ask the solar generator to modify theschedule.

48

Reactive Power & Voltage Control (6.6)

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VAR Charges under Low Voltage VAR Charges under High voltage

Beneficiary1

Voltage: < 97%

Pool Account

VAR charges

EHV grid

Beneficiary2

Q Q

Beneficiary1

Voltage: > 103%

Pool Account

VAR charges

EHV grid

Beneficiary2

Q Q

Date of commercial operation – declared by the generator afterdemonstrating the unit capacity corresponding to MCR/ Installedcapacity through a successful trial run and after getting clearancefrom the respective RLDC/SLDC.

Successful trial run- 7 day advance notice to beneficiaries/ buyers tied up/ RLDC or SLDC if no

buyer tied up- 72 Hr continuous at MCR/ Installed Capacity (with short interruption up to

4 Hr) for Thermal.- Thermal/Hydro to demonstrate capability to raise load upto 105 %/ 110 %

of MCR/ Installed Capacity- 12 Hr continuous at MCR/ Installed Capacity (with short interruption up to

4 Hr) for Hydro- 24 Hr continuous power flow for transmission element.

For commercial operation at de-rated capacity – Demonstratedcapacity should be more or equal to 105 % of the de-ratedcapacity

Commercial operation of CGS/ ISGS and ISTS( IEGC 6.3A)

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Applicable to CGS/ISGS

Technical Minimum for operation of a thermal unit shall be 55 %of MCR or installed Capacity. (of units on bar)

CGS/ISGS whose tariff is determined or adopted by CERC, to becompensated if operated below normative plant availabilityfactor upto technical minimum level.

Compensation depends upon the average unit loading dulytaking in to a account forced/planned outage, PLF, numberstart/stop, secondary oil consumption etc..

If total requisition from an ISGS is less than its Tech minimum- RLDC can schedule up to Tech Minimum as per the system requirement- Else generator has to request concerned beneficiary to increase requisition

to operate plant at technical minimum- Else plant can take one of its units on reserve shutdown, if not feasible to

operate below technical minimum.- During reserve shutdown beneficiaries shall pay capacity charge

considering units available both “on” as well as “off” bar

Technical minimum schedule for operation of CGS/ISGS(6.3 B)

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