13 and 14 December under-frequency events
Decision
The Authority received reports from the System Operator for two under-frequency events (UFEs), one on 13 December 2018 and the second on 14 December 2018.
We received three submissions on our draft determination paper. The Authority’s final determination under clause 8.61(9) of the Code is that Genesis is the causer of the UFE on 13 December 2018 and that Transpower, as the grid owner, is the causer of the UFE on 14 December 2018.
The Authority’s reasons for the final determination for the 13 December 2018 UFE are:
- the interruption/reduction of electricity occurred at the grid injection point for Huntly Unit 5, which belongs to Genesis
- no other asset was identified as having caused or potentially caused the UFE
- the system operator and Genesis agree that Genesis was the causer of the UFE.
The Authority's reasons for the final determination for the 14 December 2018 are:
- the interruption or reduction of electricity occurred when lightning struck, faulting the Huntly-Stratford One circuit in north Taranaki, triggering protection equipment to disconnect Unit 4 at the Huntly power station and causing a UFE
- Transpower is the grid owner that owns the Stratford circuit.
The Authority’s reasons for the final determination for the 14 December 2018 UFE have been published in this paper. This decision was upheld by the Rulings Panel after it was disputed by Transpower.
In accordance with clause 8.65 of the Code, the clearing manager rebates the event charges to relevant participants. The charges advised in the system operator’s reports to the Authority was $175,125 for 13 December 2018 and $225,875 for 14 December 2018.
Submissions
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Mercury Energy2 pages
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Till Renewables1 page
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Transpower6 pages