Actions resulting from under-frequency event on 12 November 2013

Planned testing of the new high-voltage, direct current (HVDC) control system caused an under-frequency event on 12 November 2013 and resulted in the activation of the automatic under-frequency load shedding (AUFLS) system in the North Island.

Clause 8.61 of the Electricity Industry Participation Code 2010 (Code) requires the system operator to determine the causer of the under-frequency event. This process requires the system operator to publish a draft determination and to consult affected parties prior to publishing the final determination. No specific timeframe for this process is specified in the Code.

Clause 8.64 of the Code allocates a charge to the causer of the event that is proportional to the reduction in generation resulting from the event. The event charge is rebated to those industry participants that are allocated costs for the provision of the reserves used to respond to events of this nature. The Code does not make any provision for compensation for consumers affected by the event.

Given the high degree of public interest, and recognising that the activation of AUFLS is a rare and significant event, the Authority is also seeking further information from Transpower about the event to confirm Transpower complied with the Code and to better understand whether there might be implications for the Code or for the reliable and efficient operation of the electricity industry. The Authority will determine whether to refer this issue to the Security and Reliability Council once it has received and considered the report from Transpower.