The potential opportunity of a lower-cost, higher performing frequency control regime has been lost in the AEMC’s draft rules. Lower inertia would be better managed and costs of controlling it would be lower if the frequency control regime called upon fast frequency response solutions available from demand management, energy storage and renewable energy.
The AEMC’s work on inertia has not drawn this link. It focuses on the goal of setting thresholds and standards within the current paradigm where poor power control dominates.
Putting the cart before the horse in this way means that the AEMC’s solution for transmission businesses to make investments that secure inertia will likely be excessive and overly conservative.
Old thermal coal generators are a liability to the security of the system
While older thermal generators are playing havoc with the grid frequency, the AEMC has also reaffirmed the fact that they are an unreliable source of inertia.
There is no evidence that they would remain in operation through high speed frequency changes, even those expected today. Prior to 2007 there was no standard for generators to remain in operation for high speed frequency changes. All of the NEM’s thermal coal generators, except Kogan Creek, were commissioned prior to 2007.
Unlike the advanced technologies deployed in renewables which can withstand major disturbances and frequency changes easily, there is no basis on which customers should have confidence in the performance of most of the thermal generators in the NEM. These generators may simply shut down during major power system disturbances, having a major impact on energy security. Relying on them to provide inertia to support the grid is untenable.
The AEMC’s final ruling must make it clear in the National Electricity Rules that only generators with clearly stated and known performance during power system events can provide services that support these events. Testing and certification of this capability must be a requirement to register to provide the service.
[1] https://reneweconomy.wpengine.com/inertia-power-system-dont-actually-need-much-65691/
[2] Australian Energy Market Operator, ‘FREQUENCY MONITORING – THREE YEAR HISTORICAL TRENDS’, December 2016, page 4.
[3] Australian Energy Market Operator, ‘Causer Pays Workshop 2 (presentation)’, April 2017.
[4] K. Summers, ‘Fast Frequency Service – Treating the symptom not the cause’, February 2017.
[5] Contact details can be found here https://www.aemo.com.au/Stakeholder-Consultation/Industry-forums-and-working-groups/Other-meetings/Ancillary-Services-Technical-Advisory-Group
Tom Butler is head of policy for the Clean Energy Council.