Voltage Security Margin Assessment

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Voltage Security Margin Assessment

• By Drs. G. Huang and A. AburStudents N. Nair,
  L. Zhao
• H. Zhang( not paid through pserc)

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Task 1 Modeling of control devices, loads and
transactions for stability evaluations.

• Modeling FACTS devices 70 Finished
• Modeling Tap-changing transformers for its
  reactive power drawing capability 70 Finished
• Modeling exciters 70 Finished
• Modeling loads 70 Finished
• Modeling transactions 40 Finished

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Highlights

• Insight on Dynamic Reserve vs Static Reserve
• ( dynamic reserve paper)
• Margin based on Static Analysis is 10 too
  optimistic for most cases
• TCUL has major impacts on dynamic margin 30 or
  more
• Voltage regulating exciters cannot be replaced by
  static var reserve.

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Task 2 Use of Stability Margin and Stability
Index Calculations

• Develop a program according to the new models to
  simulate the dynamic responses 70 Finished
• Analysis of Modeling Impacts 40 Finished
• Use of stability indices as a transaction
  scheduler
• Use of utilization indices as basis for auxiliary
  service charges
• Develop equipment investment indicators
• Tests and documentation

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Highlights

• Weakness of PV curves are found. For some loads,
  the lower part of the PV curve do not indicate
  instability.
• Indicator L gives an information as regards to
  the stability margin from the steady state
  voltage collapse point.
• It has been observed that L calculated on the
  simulated dynamic data at the instance of the
  largest dip in the voltage at the load bus
  following a disturbance can give information as
  regards to the voltage stability margin.
• An OPF based algorithm to evaluate load
  curtailment incorporating voltage stability
  margin has been formulated based on the proposed
  index L.

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Task 3 Transaction based stability margin and
utilization factors calculation

• Formulate the transaction based power flow
  analysis problem 70 finished
• Develop software for transaction based power flow
  analysis for decompositions 50 finished
• Develop software to calculate utilization factor
  for control equipments
• Develop software for finding decomposed
  utiliziation factors and stability margins for
  individual transactions.
• Test case and documentation

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Highlights

• A transaction based power flow (TBPF) analysis
  and prototype program has been developed.
• The utilization of MW flows, Mvar flows, MVA
  flows, transmission losses and reactive power
  losses of bilateral transactions is part of the
  TBPF solution.
• Potentials for the deregulated power market, such
  as loss allocation, parallel flow evaluation,
  congestion management and settlement, reactive
  power pricing, Flowgate and ATC assessment etc
• High computation efficiency
• With appropriate logic modification, common power
  flow programs embedded in EMS function can be
  readily extended for TBPF purpose.

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Desired Input from Industry

• Real measurement data that records voltage
  stability scenarios for us to check if our L
  index will correctly predict the problem.
• Real measurement data that indicate PV curve
  monitoring do not work for lighting or resistance
  loads. But we will demonstrate that our L
  indicator will work.