Final determination of who caused the 13 December 2018 under-frequency event

One supportive submission was received, accordingly the Authority’s final determination under clause 8.61(9) of the Code is:

Genesis Energy Limited (Genesis), is the causer of the under-frequency event on 13 December 2018 at 2.25 pm. The Authority’s reasons for this final determination are:
a. the interruption/reduction of energy occurred at Unit 5 at the Huntly power station, which belongs to Genesis
b. no other asset was identified as having caused or potentially caused the UFE
c. in the system operator’s view, Genesis is the causer of the UFE
d. in reply to a system operator letter, Genesis has accepted that it was the causer of the 13 December 2018 UFE.

In accordance with clause 8.65 of the Code, the clearing manager rebates the event charge to relevant participants. The charge advised in the system operator’s report to the Authority was $175,125.

Final determination of who caused the 14 December 2018 under-frequency event

Three submissions were received, submissions are discussed in our decision document published below.

The Authority’s final determination under clause 8.61(9) of the Code is:

Transpower New Zealand Limited, as the grid owner, is the causer of the under-frequency event on 14 December 2018 at 12.20 pm. The Authority’s reasons for this final determination are:
a. the interruption or reduction of electricity occurred when lightning struck, faulting the Huntly-Stratford One circuit (Stratford circuit) in north Taranaki triggering protection equipment to disconnect Unit 4 at the Huntly power station and causing a UFE
b. Transpower is the grid owner that owns the Stratford circuit.

In accordance with clause 8.65 of the Code, the clearing manager rebates the event charge to relevant participants. The charge advised in the system operator’s report to the Authority was $225,875.