Post on 18-Nov-2020
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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