New review to address deteriorating frequency performance in the power system

07 November 2017

The AEMC today published an issues paper for its review of the regulatory and market frameworks needed to support frequency control in the national electricity market (NEM).  

The generation mix is changing. As newer types of generators like wind and solar come in, and conventional generators like coal retire, this is presenting challenges for the management of power system frequency. A decline in the provision of frequency response capability and an increase in connection of variable generating technologies has led to a recent deterioration in frequency performance. If frequency becomes unstable or changes too fast then the system is at risk of going black.

As well as exploring challenges facing frequency control in the power system – this review will explore opportunities to more effectively manage system security through new fast response technologies and distributed energy resources.

Areas for consideration include:

  • Primary frequency control drawing on AEMO investigations to assess whether mandatory generator governor response requirements should be introduced
  • Frequency control ancillary services in the transforming market and whether new technologies, like wind farms and batteries, offer the potential for frequency response services that act much faster than traditional services to more effectively control frequency
  • Distributed energy resources providing opportunities to support frequency control.

There are trade-offs to be made between the risks and costs of meeting system security requirements. The objective of the review is to recommend the combination of changes that are necessary to provide a secure power system at the lowest cost to consumers.

The AEMC encourages stakeholders to share their views on the paper. Submissions due by 5 December 2017.

The review is considering appropriate frequency control arrangements as the electricity system evolves. This work is part of the AEMC’s ongoing system security work program and progresses recommendations of the Finkel review into the future security of the NEM.

The review will also be informed by a technical working group, comprising network businesses, generators, retailers, energy service providers, consumer representatives, AEMO and the Australian Energy Regulator (AER).

The Commission will provide a progress report on the review to the COAG Energy Council by the end of 2017, with a final report due in mid 2018.

Media: Prudence Anderson, 0404 821 935 or (02) 8296 7817

Explainer of technical terms

How is reliability and security managed in the national electricity market?

To keep the lights on, the power system needs to be:

  • secure – able to operate within defined technical limits, even if there is an incident such as the loss of a major transmission line or large generator
  • reliable – have enough capacity (generation and networks) to supply customers.

The Australian Energy Market Operator (AEMO) is responsible for maintaining power system security and reliability in accordance with standards and guidelines, including those set by the AEMC’s Reliability Panel.

What is a secure power system?

The power system is in a secure and safe operating state if it is capable of withstanding the failure of a single network element or generating unit.

Security events are caused by sudden equipment failure (often associated with extreme weather or bushfires) that results in the system operating outside of defined technical limits, such as voltage and frequency.

What is a reliable power system?

A reliable power system has sufficient generation and network capacity to meet the consumer load in that region. It’s about having enough electricity generation and demand response to meet consumer demand.

Reliability events are caused by insufficient generation or network capacity to meet consumer load.

Reliability events due to insufficient generation and interconnector capacity are usually predicted ahead of time by supply and demand forecasting. The associated consumer load shedding may be shared across parts of the NEM.

What is power system inertia?

The ability of the system to resist changes in frequency is determined by the inertia of the power system. Inertia is provided as a consequence of having spinning generators, motors and other devices that are synchronised to the frequency of the system. Historically, in the NEM, plentiful inertia has been provided by synchronous generators, such as coal and gas-fired power stations and hydro plant.

However, many new generation technologies, such as wind turbines and photo-voltaic panels, are not synchronised to the grid, have low or no physical inertia, and are, therefore, currently limited in their ability to dampen rapid changes in frequency.

What is the rate of change of frequency (RoCoF)?

The rate at which the frequency changes determines the amount of time that is available to arrest the decline or increase in frequency before it moves outside of the permitted operating bounds. AEMO may constrain the power system to reduce the size of a potential contingency and minimise the resulting initial frequency change. Alternatively, an increase in the level of inertia in the power system would permit the occurrence of larger contingencies for a given level of initial RoCoF.