Rule Change: Completed


On 30 March 2017, the AEMC published a final rule and final rule determination on the Emergency Frequency Control Scheme rule change request.
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On 30 March 2017, the AEMC published a final rule and final rule determination on the Emergency Frequency Control Scheme rule change request.

The final rule establishes an enhanced framework for emergency frequency control in the National Electricity Market. The final rule includes:

  • a framework to regularly review current and emerging power system frequency risks, and then identify and implement the most efficient means of managing emergency frequency events,
  • an enhanced process to develop emergency frequency control schemes to allow for the efficient use of all available technological solutions to limit the consequences of emergency frequency events, including a formalised arrangement for the management of over-frequency events.
  • a new classification of contingency event, the protected event, that in the circumstances defined by such an event, will allow power system security to be managed by using a combination of ex-ante solutions, as well as some limited generation or load shedding.

This integrated framework for emergency frequency control schemes and protected events will support security of supply for consumers. However, it is important these measures are delivered efficiently, so that costs for consumers are as low as possible. The final rule sets out clear governance arrangements for both, including a robust cost benefit process, to achieve this outcome.


Emergency under-frequency and over-frequency control schemes are the last line of defence to maintain the power system following a major disturbance. They are central to keeping the power system secure.

The South Australian Minister for Mineral Resources and Energy submitted two rule changes that were designed to enhance the frameworks for emergency frequency control schemes.  These rule change requests asked the AEMC to consider various matters including:

  • Clarifying the roles and responsibilities of different parties.
  •   Developing a new sub category of non-credible contingency event for which AEMO should maintain system frequency.
  • Developing a new framework in the NER for the development of a scheme to deal with over-frequency events.

As these two rule change requests relate to similar matters, the AEMC decided to consolidate them with the publication of the draft determination on 22 December 2016, under s.93(1) of the National Electricity Law.

On 8 September 2016, the Commission published a consultation paper identifying specific issues for consideration by stakeholders. The Commission received seven submissions from stakeholders.

On 22 December 2016, the Commission published a draft rule determination making the draft rule as proposed. The Commission received eleven submissions on the draft rule determination from a range of stakeholders.

Submissions to the consultation paper and draft rule determination are available on this webpage.

This rule change is related to a broader package of work being progressed by the AEMC and AEMO related to power system security. The AEMC’s System Security Market Frameworks Review (the system security review) is considering power system security issues and various regulatory/market frameworks that might be used to address these issues. On 23 March2017, the AEMC published a Directions Paper for the system security review.  Further information on this project can be found at System Security Market Frameworks Review

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