Review of low residual and insufficient generation events

The Electricity Authority has published a Review of low residual and insufficient generation events from 2021 to August 2023.

The review was prompted by an increase in the frequency of tight situations, when the forecast available electricity supply may not be much higher than demand, over the last three years.

We found that despite the increase in such events in recent years there have been improvements in the handling of such situations.

Since the grid emergency of 9 August 2021, the system operator issued notices earlier than previously, giving participants more time to react, which they did by increasing reserve and energy offers where possible.

The review noted that in both 2022 and 2023. there was only an escalation of events when there were extenuating circumstances, such as equipment failures, despite periods of near-record peak demand in 2023.

We also found a general improvement in wind and demand forecasting accuracy, giving increased certainty for participants and the system operator to help manage events.

We note that despite the improvements in the handling of such situations the increase of intermittent generation in the electricity system and other factors means managing such situations will remain a challenge. The Authority continues to work with participants on system security, forecasting certainty and operations improvements to mitigate these challenges.

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