Security and Reliability Council to examine power outage

Security and Reliability Council to examine power outage

The Security and Reliability Council (SRC) will report to the Electricity Authority on yesterday’s widespread power outages across the North Island.

The SRC was established by the Authority in March this year, as required by section 20 of the Electricity Industry Act 2010. The SRC provides independent advice to the Authority on the performance of the electricity system and the system operator, and on reliability issues.

Yesterday’s outages arose from technical faults occurring at Transpower’s Huntly substation. Transpower is investigating the causes of the fault.

The SRC will consider whether the event has any implications for the longer-term reliability of the electricity system.

Transpower has been requested to provide the SRC with a report on why the event occurred, whether the backup systems worked as intended, and whether the appropriate actions were taken to restore power and return the electricity system to a stable state. The timing for Transpower’s report will be decided once the immediate issues have been dealt with.

Separately, the Authority has also commenced a market performance review into the events. This review will focus on the performance of the market during and immediately following the event. If required, the review may expand in scope to consider reliability issues.

The Authority notes that the approximately $20,000/MWh prices at Otahuhu reported in newspapers this morning are not valid prices (they are called infeasible prices in the electricity sector). Infeasible prices occur from time-to-time and are resolved in the normal course of calculating final prices.

The Authority also notes that yesterday’s power outages occurred to protect the rest of the system, using automatic relays located in distribution networks. Power to some consumers is dropped automatically when frequency on the national grid falls below 47.8 Hertz, to avoid the whole system losing power and so that electricity supply can be restored quickly. Further automatic cuts are made if frequency falls to 47.5 Hz. These types of arrangements are standard in most other electricity systems.

The system operator purchases reserves to cope with large one-off faults in the system, but large multiple faults occurred yesterday resulting in electrical relays automatically cutting power to some consumers. Yesterday’s event is a very rare occurrence, as widespread power cuts from automatic relays have not occurred in New Zealand for 15 years, with the last occurring on 3 March 1996.

More information on the Security and Reliability Council is available here.

A more detailed introduction to reserve management concepts and Automatic Under-Frequency Load Shedding (AUFLS) is available here.

ENDS

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