Promoting reliable electricity supply: Frequency-related Code amendment proposals

Upcoming Open Closed Decision

View submissions Submissions closed 17 June 2025

Decision

We have decided to progress both of the proposed Code amendments, with some changes in response to submitter feedback and input from the Common Quality Technical Group. The Code amendments are to:

lower, to 10MW, the threshold for generating stations to comply with the frequency-related asset owner performance obligations and technical codes in Part 8 of the Code
specify a permitted maximum dead band of the greater of ±0.1Hz, or their generating unit’s inherent dead band as agreed with the System Operator.

The Code amendments come into effect on 1 July 2026.

Decision paper

Promoting reliable electricity supply - Frequency-related Code amendments - Decision paper

Consultation

Thanks to all who engaged with this consultation. We are considering all submissions and plan to publish our decision paper soon.

This consultation sought feedback on our proposal to amend Part 8 of the Code to address the frequency-related common quality issue, which is described as:

An increasing amount of variable and intermittent resources, primarily in the form of wind and solar photovoltaic generation, is likely to cause more variability in frequency within the ‘normal band’ of 49.8–50.2Hz, which is likely to be exacerbated over time by decreasing system inertia.

We are proposing to:

lower the 30 megawatt threshold for generating stations to be automatically excluded from being required to comply with aspects of Part 8 of the Code. These are the frequency-related asset owner performance obligations and technical codes
set a permitted maximum dead band beyond which a generating station must contribute to frequency management and frequency support.

These proposed changes will benefit consumers by:

promoting a reliable electricity supply by improving frequency stability and reducing the risk of an automatic under-frequency load shedding event
promoting efficiency by reducing the need for the system operator to procure additional ancillary services, lowering the possibility of future cost increases.

Consultation paper