Jun 2016
Electricity Distribution
Transient Voltage Stability of Inverter Dominated Grids and Options to Improve Stability
Jun 2016
Jun 2018
National Grid Electricity System Operator
Yun Li / Richard Ierna
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Network Innovation Allowance
ED - Network improvements and system operability
Active Network Management and System Security
The work would be carried out in 2 phases and would comprise the following scope.

Phase 1 (End-October 2016 Completion):

  1. Create a PSCAD model of the GB grid suitable for demonstrating inverter-induced instability phenomena. This would be based on an existing National Grid reduced equivalent model. The model will include a full representation of the network of the 400kV network on the South coast between Lovedean and Kemsley substations with the representation being simplified in areas further away from the Lovedean-to-Kemsely zone.

  2. Run a series of study cases looking at realistic future GB operating conditions and generation/demand backgrounds to build a picture of likely voltage transient instability. Explore the use of synchronous compensation as a counter-measure to voltage instability. Provide a report describing the risk of inverter induced instability phenomena and limits for the operation of non-synchronous generation (NSG).

  3. Carry out an analysis to benchmark the costs of maintaining voltage stability through the use of synchronous machines and the curtailment of inverter connected generation.

Phase 2 (End-June 2017 Completion):

  1. Demonstrate a novel inverter control approach (“Advanced Converter Control”), with the demonstration focused on the South Coast area. Outline the potential wider GB benefits of this approach.

  2. Provide a plan with recommendations on how the approach can be fully developed and implemented.
  • Create a PSCAD model of the equivalent GB transmission network.
  • Demonstrate whether fast transient voltage instability is a significant concern for the GB system given likely future generation backgrounds.
  • Identify at what levels of non-synchronous generation (NSG), fast transient instability would occur.
  • Assess the likely costs of stability restrictions based on conventional approaches using synchronous generation and synchronous compensation to maintain stability.
  • Identify whether the proposed Advanced Converter Control solution can improve system stability.
  • Provide a programme of work to further develop, test and implement the proposed approach.
The project will be successful if we :

  1. Create a functioning PSCAD model for the GB network that can be used for transient stability analysis.

  2. Determine whether the GB system is likely to be at risk to voltage instability with high levels of NSG.

  3. Identify the levels of NSG at which the GB network is likely to be susceptible to instability problems and the likely cost impacts of these restrictions if new mitigation approaches cannot be developed.

  4. Confirm whether the Advanced Converter Control approach could be an effective mitigation strategy.

  5. Identify how the improved control approach can be developed and implemented.