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System security and resilience

Improving the accuracy of intermittent generation forecasts

Improving the accuracy and frequency of intermittent generation forecasts in the spot market.

  • Generation
  • Policy

    • Overview

    Intermittent generation forecasts are often inaccurate and unreliable until close to real time. Inaccurate forecasting is prevalent because there are minimal obligations around the accuracy of intermittent generation forecasts. Intermittent generators have few incentives to forecast accurately as there is little correlation between forecasting accuracy and revenue earnt in the spot market.

    Thanks to all those who provided feedback on our consultation to improve uncertainty in intermittent generation forecasts in the spot market. We are considering all submissions before we decide which option to progress.

    Timeline

    Past activity

    • Winter 2024

      Intention —

      Implement policy solution

    • 14 June 2023

      Consultation —
      Forecasting provisions for intermittent generators
      View consultation

    • 17 October 2022

      Review —

      Accuracy of wind generation, demand forecasts and bids from April 2021-March 2022

    Project background

    Incorrect forecasting by wind generators was a contributing factor in the 9 August 2021 grid emergency, which resulted in the disconnection of approximately 34,000 customers without warning.

    In response to this grid emergency, the Electricity Authority (and other organisations) conducted a number of reviews and investigations to:

    • understand the causes of power supply interruptions
    • understand the industry’s response on the night
    • learn lessons from the event to identify and recommend improvements to ensure similar circumstances are better managed in future.

    In response to one of the review’s recommendations, we published an information paper about the accuracy of wind generation, demand forecasts and bids leading up to real time from April 2021 to March 2022. We found that intermittent generation forecasts are often inaccurate and unreliable until the last three and a half hours before real time.

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