SYSTEM PERFORMANCE

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Grid Interconnections and Issues
Subir Sen Chief Design Engineer Power Grid
Corporation of India Ltd.
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Objective

• Optimum Utilisation of Energy Resources
• Harnessing the energy resources
• Utilizing the time diversity between regions
• Utilizing the relative locations of the
  generating resources and load centres between
  two regions
• Sharing of spinning reserve
• Optimal Hydro-Thermal Mix
• Development of clean hydro power/renewable energy
• Economy of scales
• By connection to large sized power system, large
  sized generating stations can be established.

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Objective
. Contd

• Improved Security and Reliability
• Cutting Investment by optimizing Spinning
  reserves Improved stability
• Mutual support during Emergency
• Economic Benefit
• Exporting country would earn revenue by exporting
  power and the importing country can defer the
  investment

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Objective
. Contd

• Optimized Transmission Network
• Reduction in Line length
• Less capital cost
• Reduced transmission losses
• Increased economic efficiency in system operation
• Merit order operation on larger scale
• Reduced Environmental Damage

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Opportunities for Interconnection

• Evolving Open Electricity market
• Countries with limited resources would be
  benefited
• Thermal resources cheaper to transport in
  electricity form Hydro resources can only be
  transported in electricity form
• Huge hydro Resources of Nepal can be effectively
  utilized
• Exporting countries benefited economically,
  Importing countries benefited by deferring
  investment towards setting up power plants

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Indian Power Scenario
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Energy Resources Distribution in India

• Hydro potential in NER and upper part of NR
• Coal reserves mainly in ER
• Distribution of energy resources and consumption
  centres are extremely unbalanced
• Necessitates establishment of large no. long
  distance lines interconnection of all the 5
  Regional Grids

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Evolution of Grid Interconnection in India
National
Regional
State
Local
1960s
1970s
1990s
1950s
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Indian Power Scenario- At a Glance
Surplus Regions
Hierarchy of Indian Power System
NR
34,220 MW
NER
2300
2400
ER
WR
16,550MW
37,100 MW
36,570 MW
Installed Capacity 126,840 MW (Th Hy Nu -
66 26 3) Peak Demand 95,600 MW
Energy growth 8-9 per annum
Deficit Regions
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Future Power Supply Scenario
By the year 2011-12

• Peak demand (expected)- 150,000 MW
• Installed Capacity envisaged - 203,529MW
• Capacity of Interregional Links about 39,700 MW

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Interregional Links - Present
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Interregional Links By 2012
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Pushing Technological Frontiers
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Technology Upgradation Economy

• Two pronged approach adopted
• Capacity enhancement of existing transmission
  lines
• Build high capacity transmission lines

BHIWADI
BALLABHGARH
TCSC
Sub-Station Automation for increased efficiency
Installation of Series Capacitor Direct benefits
Indirect benefits -
Saving in investment - No additional
corridor - Increase in capacity
Uprating and Upgrading of Existing Transmission
Lines

• 765 kV tower with reduced RoW requirement of 64 m
  
• Pole type tower for urban areas
• Compact/Multi-circuit tower

Compact Sub-Stations with reduced Land Requirement
?800kV HVDC Geographical Information System/GPS
HSIL
Reduced Corridor Requirement
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System Availability

• At par with international standards

• Prudent operation maintenance techniques
  adopted such as
• Hot line maintenance
• Thermo-vision scanning
• Emergency Restoration System

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Interconnection - Opportunities
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Interconnection Indian Experience

• Exchange of energy across regions
• Economic benefit
• In 2005-06, about 38,000MU energy exchanged
  across the regions
• Deferred investment of about US 5580 million
  towards installation of new 6000MW power plant
• Net savings of US 360 million on account of
  cheaper power
• Improved grid conditions viz. frequency/voltage
• Reduction in Grid disturbances

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International Experiences

• Worldwide Trans border interconnections are on
  rise on account of
• Need of meeting growing power demand
• Concentration of various types of energy in
  different countries
• Economy of scales
• Decrease in operational cost through better
  resource management
• Environment Friendly through usage of renewable
  resources
• Cutting Investment by optimizing Spinning
  reserves requirement
• Trans-country grid developed progressively
• Our Region requires accelerated effort to catch
  with International development
• Rapid steps needed for co-operation in our region
  to reap benefits of Interconnections for mutual
  benefits

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South Asian Countries Energy Resources

• India Dominated by Coal
• Nepal High dependence on hydro
• Bangladesh Dominated by natural gas
• Bhutan High dependence on hydro
• Sri Lanka Dependence on petroleum

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Existing Interconnection

• India Nepal
• India Bhutan

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India Nepal Grid Interconnection

• Presently 16 nos. links at 132/33/11 kV voltage
  level
• About 50 MW power being exchanged
• Net export to Nepal (about 10 of demand of Nepal
  met through imports from India)
• Supply of 70MU/annum from Tanakpur (India) to
  Nepal

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India Bhutan Interconnection Existing

• Chukha HEP (4x84 MW), Bhutan connected with
  Indian system
• Project built with Indian technical and financial
  assistance
• Interconnecting Line
• Chukha(Bhutan) Birpara(India) 220kV 3 ckts.

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India Bhutan Interconnection Existing

• Kurichu HEP (4x15 MW) of Bhutan connected to
  Indian Grid
• Interconnectiong line
• Geylegphug(Bhutan) Salakati(NER) 132 kV line
• 3 nos. of 33 kV links are also in service
  between India and Bhutan

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India Bhutan Interconnection Benefit

• Benefits to Bhutan
• Earning of about US 48 million (Rs. 2170
  million) annually from Chukha Power
• Earning of US 10 million (Rs. 490 million)
  annually from Kuruchu Power
• Benefits to India
• India have access to environment friendly hydro
  power
• Deferred investment of US 290 million towards
  installation of 325MW power plant

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Interconnection India Nepal

• Large potential projects being considered for
  development and export of power to India
• West Seti HEP 750 MW
• Arun HEP 685 MW
• Pancheshwar HEP 6,500 MW

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India Bhutan Interconnection On Going

• Tala HEP(1020MW) to be interconnected with Indian
  grid by 2006.
• Interconnecting Line
• Tala(Bhutan) Siliguri 400kV 2xD/c
• Tala transmission system shall facilitate
  transfer of power from Bhutan to NR(India)

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Issues
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Types of Interconnection

• Interconnection is an evolving process..
• The grids of any two countries may be connected
  to support bilateral exchange of energy through
• Radial interconnections
• Either Generator or Load radialization
• Requires small investment therefore suitable for
  making a beginning gain experience on
  operational and commercial aspects
• Asynchronous links
• Asynchronous connections are robust and quite
  insensitive to variations in system parameters
• Facilitate controlled power exchange between the
  grids
• Disturbance in one system shall not spread to
  other systems
• Synchronous links
• Based on experience gained above, possibility of
  synchronous interconnection can be explored.

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Radial Inter-connection

• Technical Aspects
• Despatch Modalities
• Reliability Security aspects
• Commercial Mechanism
• Pricing of power Tariff mechanism
• Payment Security Mechanism
• Terms for Indemnification for disruption of
  Transmission service
• Common standards/accuracy for metering
• Legal Aspects
• Firming up of procedures for dispute settlement
  and Arbitration
• Applicability of Laws of Respective countries/
  International Laws
• Share of international experience on bulk power
  exchange

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Asynchronous Connection

• HVDC links
• All the above aspects
• Technical aspects
• like Short Circuit Strengths
• Operation of Interconnection including grid code
• Institutional Arrangements
• Identification / Creation of Common Agency to
  regulate, administer and operate the
  Interconnection
• Establishment of Co-ordination Centres to Govern
  the Operational matters on Daily and Short Term
  basis
• Load despatch centre of each country coordinate
  with Tr. utility

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Synchronous Interconnection

• AC Tie lines
• All the above aspects
• High level of coordination between two grids
• Technical Aspects
• Detailed system studies (load flow, dynamics,
  contingency, short-circuit etc.) by joint
  technical committee
• Operation of Interconnection including grid code
• Common operation Maintenance procedures
• Technical parameters of equipment, safety rule
• A coordination committees supported by
  sub-committees on Technical, Operational,
  Commercial aspects etc need to be established

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Energy Market - Economics

• Economy of Power System lies in Generation
  Distribution.
• Transmission, as a business, does not offer much
  economics.
• Natural Monopoly
• Only carrier of power between Generators
  Distributors
• Market Facilitator, Catalyst for overall
  development
• About 15 of total investment as against
  desirable 25.

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Market Mechanism

• Market Mechanism not only depends on Grid
  Interconnection but also on
• Development of Robust Wire network
  Distribution system
• Development of strong Control System at
  State/Regional/National level for transparency in
  system operation
• Dedicated Communication Network
• Provision of Open Access
• Coordination between independent entities-
  Generation, Transmission, Distribution, System
  Operator, Traders and Regulators
• Sound Commercial mechanism

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Conclusion

• Grid interconnection evolving process, is
  beneficial
• Optimal utilisation of resources
• Optimised transmission network
• Improved grid operation
• Economic efficiency
• Infrastructual issues to be addressed
• Type of interconnection, reliability criteria
• Harmonisation of Grid Standards and Codes
• Commercial mechanism

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Thank You