Media release

13 March 2017

Transpower releases initial report into South Island AUFLS event

Transpower has today released its preliminary report into the loss of supply event which affected some parts of the South Island on Thursday 2 March.

The report outlines what happened, the impact of the outage, how the power system reacted and the restoration process.

While there is never a good time for an outage, the report confirms the National Grid responded well on Thursday 2 March. Transpower’s automatic systems worked as they should, restoring most power supply within an hour and preventing further outages on a wider scale.

Transpower is currently finalising the scope for a full, more detailed investigation into this incident. This second report will explore the circumstances that caused the event, review the effectiveness of the event response and identify any areas for improvement.

The report can be found at the top of this page: https://www.transpower.co.nz/system-operator/key-documents/reports

Background information:

• Transpower uses a system called Automatic Under Frequency Load Shedding (AUFLS) to prevent power system collapse and blackout following large, rare system events affecting New Zealand’s National Grid.

• The AUFLS system acts as a ‘safety net’, dropping capacity of parts of the wider transmission network in order to pretect the network as a whole and prevent further outages.

© Scoop Media