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Monitoring, compliance and enforcement

Under-frequency event determinations

As the regulator of the New Zealand’s electricity industry, we are required to investigate under‑frequency events and allocate event charges accordingly.

Overview

When an under‑frequency event happens, it is our job to determine who caused the under-frequency event in order to allocate charges to the causers.

We consult on our draft determinations about who caused an event, and we consider all submissions before publishing our final determinations. We do not need to consult if the alleged causer accepts it was responsible for the event.

Timeline

Past activity

Project background

An under-frequency event (UFE) is an interruption or reduction of electricity into the electricity grid, or an interruption or reduction of electricity injected from the HVDC link into the South Island HVDC injection point or the North Island HVDC injection point.

A UFE is caused by an interruption or reduction of electricity from one or more generators of electricity, or an interruption somewhere in the transmission of electricity. The causer of an under-frequency event is either an electricity generator (like Genesis, Mercury or Meridian) or a grid owner (like Transpower).

UFEs need to be avoided because the system needs to keep frequency levels stable across connect systems. Unstable frequencies can damage equipment and can have serious implications when providing electricity at a national scale.

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