Smart%20Grid%20Protection%20in%20China

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Smart Grid Protection in China
Wu Guopei Guangzhou Power Supply Bureau Guangdong
Power Grid, China
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Contents

• Smart grid in China and the challenge for
  protection
• Change from relay protection to grid protection
• Concept of grid protection system
• Reach of grid protection
• Case study

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Smart Grid in China

• China is speeding up the infrastructure of smart
  grid
• Main characteristics of Smart grid
• self-healing and adaptive
• safe, stable and reliable
• fine compatibility
• high quality and efficiency
• coordinated and economic
• friendly interaction with the users

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New Challenges for Smart Grid Protection

• Adaptive
• Flexible topology structure
• Connection with distributed generators
• Self-healing
• Preventive control under normal operation
  condition
• Automatically recover to normal state with
  minimum manual intervention

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Change from relay protection to grid protection

• Three-defense line for the safety of power system
  
• First defense line Conventional relay protection
• To safeguard power system stable operation by
  fast and selective tripping of fault elements.

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Change from relay protection to grid protection

• Second defense linePower stability control
  system
• To avoid system out-of-step by applying load
  shedding and generator shutdown according to
  pre-set control tactic.

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Change from relay protection to grid protection

• Third defense lineemergency control
• Designed to prevent from system collapse and
  large area blackout using out-of-step islanding
  and frequency voltage control.

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Concept of grid protection

• Possibility grid protection
• Development of information and storage technology
  eliminates the information isolated island in
  power system.
• Safe and realtime information exchange
• Extension from substation domain information
  interaction to power grid wide area information
  interaction.

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Concept of grid protection

• Goal
• Realize integrated and optimized protection and
  control tactic instead of isolated three-defense
  line protection system

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Research of grid protection

• Optimized protection performance
• Limit of conventional protective relay The
  selectivity of protective relays, especially back
  up protective relays, are dependent on the
  current, impedance and time settings, which may
  cause operation time delay and loss of
  selectivity.
• Accurate fault locate and precise fault isolation
  can be achieved by using wide area fault
  distinguishing information at each node.

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Research of grid protection

• Fast power recovery in regional power grid
• When the substation is loss of power due to power
  supplies out-of-service, the power supply in
  other substations will be connected according to
  system operation mode and topology state.

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Research of grid protection

• Improve the safety and reliability of
  distribution network after power recovery
• Overload caused by power recovery may affect the
  power grid reliable operation
• Load shedding shall be adopted to ensure the
  power supply to important consumers.
• Acquire pre-fault static load information through
  the wide area information interaction with EMS,
  and optimize load shedding strategy to maximally
  protect reliable power supply.

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Research of grid protection

• Improve the safety and reliability of
  distribution network with distributed power
  supply
• When distributed power supplies are connected to
  distribution network, the conventional relay
  setting regulations can not meet the requirements
  of system selectivity.
• The electrical character are varying according to
  the type of distributed power supplies during
  system fault and grid interconnection.
• Fast and precise fault locate and fault tripping
  using wide area measurement data
• Check if the distributed power supply can
  restored to interconnection or isolated island
  state after fault is cleared, and ensure the safe
  and reliable operation of distribution network by
  applying grid interconnection control and load
  shedding.

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Case study Grid protection distribution network
in China Southern Grid

• Located in financial high-tech service area of
  Guangdong
• Includes 2 substations, 65 kilometers
  distribution lines, 58 switch room ring main

• Build distributed Intelligent Self-Healing
  Control System Based on Multi-Agent
• The goals average fault outage time 5.2min/year

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Implementation of Grid protection

• Taking into account the real-time performance of
  feeder automation devices (FA) and information
  completeness of distribution automation system
  (DMS), to raise the smart level of real-time
  control.
• Distribution terminals with enhanced functions
  will be used as agents of grid protection and
  control system, to realize local signal
  acquisition pre-treatment, logic determination
  and implementation of remote commands.

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Implementation of Grid protection

• Embedded central control stations with rapid
  information processing ability will be set up,
  for fault criteria logic calculation based on
  wide-area information, to realize rapid fault
  location.
• System configuration tool shall be provided with
  graphic interface to realize system configuration
  for IEDs of smart distribution network protection.

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Implementation of Grid protection

• Wide-area information protection logics such as
  improved directional pilot protection suitable
  for distribution grid will be used, to
  effectively determine distribution grid fault
  zone connected with distributed power source at
  load terminals.

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Implementation of Grid protection

• Realize power restoration path selection function
  based on grid topology, assisted with load
  control technologies such as LF load
  disconnection, to realize rapid load restoration
  and load optimization and re-distribution.
• Micro-grid frequency and load control technology
  with multi-DG access will be tried, for
  distribution grid multi-DG coordination control
  in island operation.

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Thank you for your attention !
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