Impact of Tiwai exit

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Transpower as the System Operator has commenced analysis to determine what the impacts of Tiwai’s exit in August 2021 will have on the operation of the power system and security of supply.  This webpage will be used to share the findings of our analysis as it becomes available.

Our Approach

To understand the impacts we are investigating the following:

  • Steady-state thermal limits under N-1 and N-1-1 conditions (Will be covered in the 2020 System Security Forecast)
  • Steady-state high voltage management under light load conditions (Will be covered in the 2020 System Security Forecast)
  • Steady-state voltage stability
  • Transient angular stability
  • Over frequency reserves
  • Small signal stability
  • Automatic under frequency load shedding (AUFLS) adequacy
  • Contingency and restoration planning:
    • Black start restoration process
    • Electrical islanding process
    • Regional contingency plans

Analysis Findings

Our findings will be published here when available.

Links to Additional Information

Clutha and Upper Waitaki Lines Project Operational Information

System Security Forecast

Security of Supply Annual Assessment