System Operations through National & Regional Load Dispatch Centres

2nd Interactive Workshop on

‘Transmission & Distribution’

17th-18th April 2009

at Hotel Sahara Star, Nr. Domestic Airport, MumbaiOrganized by India-Tech Foundation

Outline• Overview of Indian Power System

• System Operation

• Power Market

• Transfer Capability

• Open Access in Inter-state transmission

• Congestion Management

• Challenges and Concerns

NEW Grid

SouthGrid

South

West

North

East

Northeast

Five Regional GridsFive Frequencies

October 1991East and Northeast

synchronized

March 2003West synchronized

With East & Northeast

August 2006North synchronized

With Central Grid

Central Grid

Five Regional GridsTwo Frequencies

Installed Capacity 147 GW

MERGING OF

MARKETS

Renewable Energy : Wind Power

Total Renewable Energy Sources ~ 13 GW

Wind Installed Capacity ~ 9 GW

Estimated Wind Potential ~ 45 GW

India: 5th Largest Wind Power Producer

Growth in Inter-regional Transmission Capacity

Source: CEA

IR CAPACITY : 20800 MW

Growth of IR Exchanges

Development of Load Despatch Centres• Initial stages

– a telephone/hotline communication system and a frequency meter– Operational only during day-time– Acted mainly as an information centre

• State grid interconnections– 24x7 operation– Rudimentary data acquisition systems

• Central Sector generating stations– Interstate scheduling and energy accounting

• Regional Grid formation & CTU– Modernization of control centres

• Availability Based Tariff– 15-minute scheduling, metering settlement– Market operation

Modernization of Control Centres• 33 SLDCs, 5 RLDCs, 1 NLDC• Round-the-clock manning • Wideband speech and data communication• Fish as well as bird eye view through SCADA• Common database in SLDC/RLDC• Common Information Model (CIM) in NLDC• Classical data presentation plus alarm processing,

exception lists, animation, geographical displays• Multilayering, Trending• SoE and replay

Jurisdiction of Load Despatch CentersNLDC:Apex body to ensure integrated operation of National Power System

RLDC:Apex body to ensure integrated operation of power system in the concerned region

SLDC:Apex body to ensure integrated operation of power system in a state31

5

Jurisdiction of RLDCs/SLDCs• Control Area

• Scheduling Responsibilities – RLDCs

• State as a whole

• ISGS /UMPPs,

• Pvt. Generating Stations > 1000 MW and

having > 50% share of state outside home state#CERC Order 58/2008, Suo Moto

– SLDCs• State Utilities ( SGS / Discoms)

• Intra-State Entities

National Load Despatch Center (NLDC)

ERLDC WRLDC NERLDC

BACKUPNLDC, KOLKATA

MAIN NLDC, DELHI

SRLDCNRLDC

F.O. Cable on each 2E1 Link

Copper Cable –(Backup)

VSAT– (Backup) each 64Kb/s

Functions of Load Dispatch Centers– Optimum scheduling and dispatch of electricity

– Monitoring of operations and grid security

– Keeping accounts of the quantity of electricity transmitted through the regional grid

– Supervision and control over the transmission system

– Real time operations for grid control

– Dispatch of electricity through secure and economic operation of in accordance with the Grid Standards and the Grid Code

Electricity Act 2003

Foundation Stones

IEGC ABT

System Operation

• Two firm footings

– INDIAN ELECTRICITY GRID CODE (IEGC)

– AVAILABILITY BASED TARIFF (ABT)

Regional Grid Operation: Philosophy

• Operated as loose power pools• States have full operational autonomy• State power system treated as notional (flexible)

control area• Very tight control of actual interchange by state

utilities & Inter State Generating Stations not mandated

• Deviations from net drawal schedules appropriately priced

GRID MANAGEMENT FUNCTIONS• Ex-ante functions

– Scheduling

• Real-time functions– Supervision & control of system parameters– Facilitating Open Access transactions

• Post-facto functions– Settlement system operation

• Interaction with stakeholders

Balancing market guiding vector

UI mechanism

• Maximizes social welfare• Transparent, neutral & rigging proof• Diffuses market power • Ultimate open access• Facilitates reforms in the sector• Encourages trade and bilateral exchanges• Facilitates exchanges (arbitrage) between regional

power pools

The End Result ….• Frequency is

– collectively controlled– democratically stabilized

• Wholesale market is workably competitive – allocative efficiency– productive efficiency

• Economic signal available for – optimum utilization of resource – investments in generation capacity

• Settlement is– streamlined – dispute-free

INDIAN ELECTRICITY MARKETENABLERS

Legislation

Indian Electricity Act 2003

National Electricity Policy

12-Feb-2005, Para 5.7.1(d)

Regulation

IEGC-Feb 2000

ABT Order-Jan2000

Open Access-May-2004

Power Exchange-Aug-2007

Execution

CTU/STU, RLDC/SLDC

Grid & Market Operation

Control Centres & SEMs

ABT settlement: in stages 2002-03

STRUCTURE

Balancing Mechanism

Frequency linked

Unscheduled Interchange

Intra-day STOA

Day-ahead Power Exchange

Multiple Power Exchanges

Short-term Bilateral

Day-ahead

First-come-first served

Three-month ahead

Long-term Bilateral

Shared resources (ISGS)

Own resources

Grid CodeFeb.’2000

SettlementSystem2002-03

Open Access2004

PX 2008

Ancillaries,

Evolution of Power Market in India

Market Design

IMBALANCESCONGESTIONMANAGEMENT

ANCILLARYSERVICES

SCHEDULING &

DISPATCH

ELECTRICITY MARKET

“Making Competition Work in Electricity”, Sally Hunt

Four Pillars of Market Design

Apr 21, 2023 22

Total Transfer Capability

Voltage Limit

Thermal Limit

Stability Limit

Total Transfer Capability

Total Transfer Capability is the minimum of the Thermal Limit, Voltage Limit and the Stability Limit

Time

Power Flow

Transmission Capacity vs Transfer Capability

Transmission Capacity Transfer Capability

1 Is a physical property in isolation Is a collective behaviour of a system

2 Depends on design only Depends on design, topology, system conditions, accuracy of assumptions

3 Deterministic Probabilistic

4 Constant under a set of conditions Always varying

5 Time independent Time dependent

6 Non-directional Directional

7 Determined directly by design Estimated indirectly using simulation models

8 Declared by designer/ manufacturer Declared by the Grid Operator

9 Understood by all Frequently misunderstood

10 Considered unambiguous & sacrosanct Subject to close scrutiny by all stakeholders

Total & Available Transfer Capability

ATC = TTC – TRM – CBM

Transfer Reliability Margin (TRM)

Capacity Benefit Margin (CBM)

Long Term Open Access (LTOA)

Short Term Open Access (STOA)

TTC

ATC

“Reliability is the performance level of the elements of the bulk electric systems that results in electricity being delivered to the customers within accepted standards and in amount desired. It is expressed in terms of the frequency, duration and magnitude of adverse effects on electric supply. Reliability comprises of Adequacy and Security…Adequacy is reliability within the range of events which can be controlled by operators whereas Security is reliability under conditions beyond the control of operators.” Dr. Mohammad Shahideopour

CERC Open Access Regulations, 2008• Effective 01.04.2008

• Permits usage of spare transmission capacity through a transparent process

• Offers choice and freedom to buy & sell power

• Transactions categorized as Bilateral and

Collective (through Power Exchange)

• Transmission Charges moved from “Contract Path” to “Point of Connection” for Collective Transaction

• Thrust on Empowerment of SLDCs

Time Line

Bilateral - Advance

Bilateral - FCFS

Collective Through

PX

Day - Ahead

Bilateral - Contingency

Trade under Short-Term Open Access

17

2324

3130

778

3938

5933

11781

9560

12

14

16

18

20

22

24

26

28

30

32

2004-05 2005-06 2006-07 2007-08 2008-09

En

erg

y (

BU

s)

----

->

0

5000

10000

15000

Nu

mb

er

of

Tra

ns

ac

tio

ns

---

->

Volume of trade (BUs) No. of transactions

* 2008-09 data includes Bilateral + Collective transactions.

0

500

1000

1500

2000

2500

3000

Month -------->

En

erg

y (

MU

s)-

----

----

-> 2007-08

2006-072005-06

ENERGY APPROVED(MU) - (Nodal RLDC-NRLDC)

2008-09

0

100

200

300

400

500

600

700

800

900

1000

APRIL MAY JUNE JULY AUG SEP OCT NOV DEC JAN FEB MARMonth -------------->

App

rove

d E

nerg

y(M

Us)

----

-->

2007-08 2006-07

2005-06

2008-09

ENERGY APPROVED(MU) - (Nodal RLDC-SRLDC)

Growing Confidence in Open Access Market - Increasing Market Players

Power Exchange in India• Salient Features

– Multiple exchanges – Competition amongst Exchanges

• Indian Energy Exchange (IEX)• Power Exchange of India (PXI)• Third Power Exchange in the offing:

– Voluntary participation– Double sided bidding– Uniform pricing– Day-ahead exchange– Hourly bids– Congestion management by market splitting

Daily Energy Traded on PX

Increasing Participation on PX

Open Access: Key Success Factors• Developed in consultation with all stake holders• Control area demarcation & boundary metering• Robust transmission system• Assessment of Transfer Capability• Balancing mechanism• Methodology for transmission charge sharing• Treatment of transmission losses• Streamlined scheduling and settlement mechanism• Transparency and non-discriminatory implementation• Compliance• Dispute redressal mechanism• Congestion management

Transmission Congestion

• Characteristics of a growing power system• Sign of optimum investment• If managed and documented

– Gives signals for future investments

• If unmanaged– A pain

– Threat to grid security

– May lead to social and economic loss

– Situation gets acute in Northern Region due to indiscriminate overdrawal

Skewed Load-Generation Balance

SR

ER+NER

WR

NR

Scenarios:

1. 4S

2. 3S + 1D (Congestion)

3. 2S + 2D

4. 1S + 3D

5. 4D

SKEWED LOAD GENERATION BALANCE

FLOWGATES

Congestion Management: Bid AreaArea

Region States

N1 North JK, HP, CHD, PUN, HAR

N2 North RAJ,DEL, UP, UTT

W1 West MP, CHTG

W2 West MAH,GUJ, GOA, DD,DNH

S1 South AP, KAR, GOA

S2 South TN, KER, PONDY

E1 East WB, SIK, BIH, JHAR

E2 East ORISSA

A1 North-East

Tripura, Manipur Mizoram, Meghalya

A2 North-East

Assam, Ar. Pradesh, Nagaland

PECULIARITIES & CHALLENGES

Skewed resource distributionLong-haulage of powerResource InadequacyWeather extremesDiversity

Dynamically varying resource sharing matrixExcessive reliance on UIFreedom and choice without enforcement of obligationsUnclear jurisdiction

High growth, high uncertaintiesUnbundling and reformsEvolving market mechanismsChanging business environment

Loose Power PoolDecentralized OperationFloating FrequencyUnscheduled InterchangeVoluntary ancillary servicesWeekly settlement 21 day cycle15-minute settlement period

DAILY OPERATIONAL CHALLENGES

FLOATING FREQUENCY: 49 - 50.5 Hz VOLTAGE VARIATIONS: 380- 430

kV

HIGH RAMP RATEBI-DIRECTIONAL LINE FLOWS

Concerns• Reliability of physical system

– Adequacy, Security, Dependability

• Rapid growth– Harmonization – Jurisdiction

• Visualization and situational awareness– Dynamic system

• Deployment of technology– Automation, Information exchange

• Capacity building– Inclusive, sustainable, broad based– Human Resource

VISUALIZATION

CHALLENGES BEFORE US

Expanding requirements

Technological up gradation

Database & display updating

Maintaining data quality

Operator familiarization

SITUATIONAL AWARENESS

Expectations• Focus on reliability of the physical system• Designing markets that complement reliability• Appreciation of System Operation as an important

function– Allocation of resources

– Automation

– Capacity building

• Grid security comes before Economics– No economic theory, no legislation, no regulation can

repeal the Laws of Physics“Power markets are the only markets that can suffer a catastrophic instability that develops in less than a second...The extent and speed of the required coordination are unparalleled.” ….Steven Stoft

Building up the Immune System• Protection

– New technologies– Co-ordination

• Power System Early Warning Systems– PMU– WAMS

• Defense mechanisms– System Protection Schemes

Thank You

sksoonee@gmail.com

sksoonee@powergridindia.com