27 June 2024 under-frequency event

The Electricity Authority's final determination under clause 8.61 of the Electricity Industry Participation Code 2010 is that Genesis Energy Limited, as the generator that owns Huntly Unit 1, was the causer of the under-frequency event (UFE) at 12.32am on 27 June 2024.

The Authority's reasons for the determination are:

• A UFE occurred at 12.32am on 27 June 2024 when frequency dropped to 49.21Hz in the North Island
• The interruption/reduction of electricity occurred at the grid injection point for Huntly Unit 1, which belongs to Genesis
• No other asset was identified as having caused or potentially caused the UFE
• Genesis agreed with the system operator’s assessment that Genesis was the causer of the UFE
• The Authority did not receive any feedback that disputed its draft determination.

In accordance with clause 8.65 of the Code, the clearing manager will rebate the event charges to the relevant participants. The event charge calculated in the system operators report to the Authority is $220,550.00.

Any dispute of this final determination can be lodged with the Rulings Panel by 5pm, 10 January 2025.

At 12:32pm on 27 June 2024 an under-frequency event occurred when 236.44MW of generation injection was interrupted or lost at the Huntly grid connection point. This resulted in a drop in frequency of 49.21Hz in the North Island and 49.25Hz in the South Island.

This consultation sought feedback from interested parties on the Electricity Authority’s draft determination that Genesis, as the generator which owns Huntly Unit 1, was the causer of the under-frequency event on 27 June 2024.

No submissions were received on the draft determination.