Consultation on 30 June 2023 under-frequency event

We are seeking your feedback on the draft determination of causer for an under-frequency event on 30 June 2023.

The normal frequency band in New Zealand is between 49.8 and 50.2Hz. An under-frequency event occurs when the frequency falls below 49.25 Hz because of a loss of injection of more than 60 megawatts into the grid.

The Electricity Authority’s draft determination under clause 8.61 of the Electricity Industry Participation Code 2010 is that Genesis Energy Limited (Genesis), as a generator, was the causer of the 30 June 2023 under-frequency event. The reasons for the draft determination are:

• the interruption/reduction of energy injected into the grid occurred at Unit 5 of the Huntly power station, which belongs to Genesis
• no other asset was identified as having caused or potentially caused the under-frequency event
• in the system operator’s view, Genesis is the causer of the under-frequency event
• in reply to the system operator’s letter, Genesis accepted that it was the causer.

The Code requires the Authority to consult with every generator, grid owner and other participant substantially affected by the under-frequency event on its draft determination.

We look forward to receiving your responses to this consultation by 5pm on 18 December 2023.

Have your say – read the draft determination of causer.

We will carefully consider all submissions received before making a final determination on the under-frequency event.

We also invite comment on the system operator’s calculation of the megawatts of power lost during the event, which the system operator uses for calculating the under-frequency event charge.