Transcript System Operations through National & Regional Load

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, Mumbai
Organized 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
Five Regional Grids
Two Frequencies
August 2006
North synchronized
With Central Grid
March 2003
West synchronized
With East & Northeast
NEW Grid
October 1991
East and Northeast
synchronized
South
Grid
Central Grid
MERGING
OF
MARKETS
North
West
South
East
Northeast
Five Regional Grids
Five Frequencies
Installed Capacity 147 GW
Renewable Energy : Wind Power
India: 5th Largest Wind
Power Producer
Total Renewable
Energy Sources ~ 13 GW
Wind Installed
Capacity ~ 9 GW
Estimated Wind
Potential ~ 45 GW
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
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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 Centers
NLDC:
Apex body to ensure integrated
operation of National Power System
RLDC:
Apex body to ensure integrated
operation of power system in the
concerned region
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SLDC:
Apex body to ensure integrated
operation of power system in a state
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)
MAIN NLDC, DELHI
NRLDC
SRLDC
ERLDC
WRLDC
NERLDC
BACKUP
NLDC, KOLKATA
F.O. Cable on each 2E1 Link
Copper Cable –(Backup)
VSAT– (Backup) each
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
Foundation Stones
System
Operation
IEGC
ABT
Electricity Act 2003
• 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
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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 MARKET
ENABLERS
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
Evolution of Power Market in India
Ancillaries,
PX
2008
Open Access
2004
Grid Code
Feb.’2000
Settlement
System
2002-03
Market Design
Four Pillars of Market Design
ELECTRICITY MARKET
SCHEDULING
&
DISPATCH
CONGESTION
MANAGEMENT
ANCILLARY
SERVICES
IMBALANCES
“Making Competition Work in Electricity”,
Sally Hunt
Total Transfer Capability
Thermal Limit
Power
Flow
Voltage Limit
Stability Limit
Total Transfer Capability
Time
Total Transfer Capability is the minimum of the
Thermal Limit, Voltage Limit and the Stability Limit
7-Jul-15
22
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
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Time independent
Time dependent
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Non-directional
Directional
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Determined directly by design
Estimated indirectly using simulation
models
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Declared by designer/ manufacturer
Declared by the Grid Operator
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Understood by all
Frequently misunderstood
10 Considered unambiguous & sacrosanct
Subject to close scrutiny by all
stakeholders
Total & Available Transfer Capability
Transfer Reliability Margin (TRM)
Capacity Benefit Margin (CBM)
TTC
Long Term Open Access (LTOA)
ATC
Short Term Open Access (STOA)
ATC = TTC – TRM – CBM
“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
Collective
Through
PX
Bilateral
- FCFS
Bilateral Advance
Day Ahead
Bilateral Contingency
Trade under Short-Term Open Access
* 2008-09 data includes Bilateral + Collective transactions.
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15000
30
28
Energy (BUs) ----->
26
24
24
10000
9560
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20
18
5933
5000
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3938
16
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778
12
0
2004-05
2005-06
Volume of trade (BUs)
2006-07
2007-08
2008-09
No. of transactions
Number of Transactions ---->
11781
3000
ENERGY APPROVED(MU) - (Nodal RLDC-NRLDC)
2007-08
2000
2008-09
1500
1000
2005-06
2006-07
500
Month -------->
FE
B
M
A
R
N
JA
EC
D
V
O
N
O
C
T
P
SE
G
U
A
LY
JU
E
N
JU
Y
M
A
PR
IL
0
A
Energy (MUs)---------->
2500
1000
Approved Energy(MUs)------>
900
ENERGY APPROVED(MU) - (Nodal RLDC-SRLDC)
800
700
2008-09
600
500
400
300
200
2007-08
2006-07
2005-06
100
0
APRIL MAY JUNE JULY AUG SEP OCT NOV
Month -------------->
DEC
JAN
FEB
MAR
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:
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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
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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
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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
Skewed Load-Generation Balance
NR
Scenarios:
1. 4S
WR
ER+
NER
2. 3S + 1D
(Congestion)
3. 2S + 2D
4. 1S + 3D
SR
5. 4D
FLOWGATES
Congestion Management: Bid Area
Are
a
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
NorthEast
Tripura, Manipur
Mizoram,
Meghalya
A2
NorthEast
Assam, Ar.
Pradesh,
Nagaland
PECULIARITIES & CHALLENGES
Skewed resource distribution
Long-haulage of power
Resource Inadequacy
Weather extremes
Diversity
High growth, high uncertainties
Unbundling and reforms
Evolving market mechanisms
Changing business environment
Loose Power Pool
Decentralized Operation
Floating Frequency
Unscheduled Interchange
Voluntary ancillary services
Weekly settlement 21 day cycle
15-minute settlement period
Dynamically varying
resource sharing matrix
Excessive reliance on UI
Freedom and choice without
enforcement of obligations
Unclear jurisdiction
DAILY OPERATIONAL CHALLENGES
FLOATING FREQUENCY: 49 - 50.5 Hz
BI-DIRECTIONAL LINE FLOWS
VOLTAGE VARIATIONS:
380- 430 kV
HIGH RAMP RATE
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
[email protected]
[email protected]