On 18 April 2019, The Reliability Panel published a final determination and a revised FOS for stage two of the review of the frequency operating standard (FOS). This review was undertaken in two stages to accommodate interactions with related work programs.

Under the National Electricity Rules, the Australian Energy Market Operator (AEMO) must keep the power system stable and securely operating at a frequency close to 50 hertz. The specific frequency requirements that AEMO must meet under different power system conditions are set out in the frequency operating standard, which is determined by the Reliability Panel. This review investigated the appropriateness of the settings in the standard, in light of the ongoing energy market transformation as conventional synchronous generation leaves the market and non-synchronous generation such as wind and solar panels enters the market.  

On 19 December 2019 the Reliability Panel published a revised version of the final determination and a revised FOS for stage two of the review of the frequency operating standard (FOS). The revised version corrected a typographical error in table A.3 of the FOS.

Stage one

Stage one was completed in November 2017. This first stage addressed primarily technical issues and market framework changes stemming from the new Emergency frequency control scheme Rule, including the new category of protected contingency event in the FOS. At the conclusion of stage one, the Panel made a new version of the FOS, effective 14 November 2017.The changes made in this new version of the FOS included: 

• implementation of changes already made to the National Electricity Rules, through the Emergency frequency control schemes rule.
• clarification and further guidance as to how AEMO operates the power system, particularly as this relates to managing different kinds of contingency events.

Stage two 

Stage two commenced on 26 July 2018 and was completed with the publication of a final determination and a revised FOS on 18 April 2019. Stage two of the FOS review assessed and resolved remaining issues identified in stage one of the review, except for the following issues that relate to how the National Electricity Rules set out the components of the FOS: 

• the requirements in the FOS for frequency performance during normal operation 
• a standard for the rate of change of frequency in the power system 

These issues are being considered by the AEMC as part of the frequency control work plan that has followed our Frequency control frameworks review.

Final determination

On 18 April 2019, the Panel published a  Final determination and a revised FOS which addressed a number of issues that were identified through stage one of this review. The revised FOS includes changes in relation to:

• the limit on the size of the largest generation event in the Tasmanian power system
• improvements to the structure and consistency of the FOS.

This final determination also includes a summary of the Panel’s consideration of: 

• the settings in the FOS that relate to contingency events
• the limit in the FOS on accumulated time error. 

On the advice of AEMO, the Panel has maintained the existing settings in the FOS in relation to these issues, noting that the immediate priority is the joint AEMC-AEMO frequency control work plan published as part of the final report for the Frequency control frameworks review. The revised FOS will take effect on 1 January 2020 to allow for affected parties to make arrangements to adjust to the revised requirements.