Wholesale electricity prices decrease in March

12 April 2005

Wholesale electricity prices decrease in March

Climatic factors had an influence in the decrease in average wholesale electricity prices in March. These factors included above average hydro inflows and lower temperatures than were experienced last month. Average monthly prices at the Haywards, Otahuhu, and Benmore reference nodes in March were all approximately 15% lower than February.

The Taranaki Combined Cycle (TCC) plant at Stratford, removed for planned maintenance in February, extended longer than anticipated and only generated power in the last 3 days of March. Otahuhu B was removed from service on 26 March as a result of an unplanned outage. It did not return to service in March.

Flows over the HVDC inter-island link were restored to full capacity, 1040MW north and 626MW south, on 28 March at 21:30. Prior to the restoration of full capacity HVDC flows had been limited to 886MW northward transfer. During March there were two outages of HVDC components that affected maximum flow limits. On 26 March an unplanned outage of Pole 1 resulted in a maximum transfer of 500MW northwards between 18:30 and 23:30. Pole 1A was removed from service on 30 March at 06:00 for planned maintenance. This planned outage reduced maximum northward transfer to 824MW for the remainder of March. Full capacity aside these limits were often binding during March, sometimes resulting in noticeable price separation between the North and South Islands.

Hydro inflows in February were 112% of average for the month and national storage stood at 114% of average for that time of the year at 31 March. Inflows of 218% of average were recorded between the 6th and 12th of March. These inflows resulted in national storage rising to 121% of average on 11 March before decreasing throughout the rest of March to the month end figure.

For more information on electricity prices and hydrological conditions, visit: www.comitfree.co.nz

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