Energy Spectrum Australia

Energy Spectrum Australia | Issue 16

Welcome to the sixteenth edition of Energy Spectrum Australia.

The below extract has been taken from our sixteenth edition, and if you have enjoyed reading this article and want to read more about the latest developments in the Australian energy market, please contact Ben Cerini, b.cerini@cornwall-insight.com.au for more information.

AEMO makes recommendations to mitigate frequency risks

On 22 December 2020 AEMO issued the Power System Frequency Risk Review Stage 2 Final Report. This sets out the findings of AEMO’s integrated, periodic review of major power system frequency risks associated with non-credible contingency events in the National Electricity Market (NEM). Five non-credible contingency events have been identified and recommendations to solve the issues.

AEMO undertakes the Power System Frequency Risk Review (PSFRR) every two years, in order to consider the potential for “non-credible” power system contingency events to cause changes in frequency that are large enough to initiate generator disconnections and result in major transmission outages. The five priority events identified for consideration, that would lead to certain market separations are outlined in Figure 1.

Following the identification of these events in the PSFRR, AEMO has made a number of recommendations. In regards to modifications to existing emergency frequency control schemes, all network service providers will review the design of existing under-frequency load shedding (UFLS) schemes to ensure effectiveness and avoid UFLS trip of back-feeding distribution feeders. The report also recommends that ElectraNet work on enhancements to the reliability of South Australia’s System Integrity Protection Scheme by implementing a Wide Area Protection Scheme.

To prevent separation between CQ and SQ, the report recommends that Powerlink, in consultation with AEMO, continues to work on enhancing the CQ-SQ special protection scheme to successfully manage the non-credible loss of the Calvale – Halys double-circuit transmission line. This includes identifying control actions that can minimise the potential loss of synchronism across the remaining CQ-SQ circuits and loss of synchronism across QNI, and the impact of increased transfers across QNI that may result once the committed QNI upgrade is completed.

Other recommendations include AEMO and ElectraNet reviewing and expanding the South Australia over-frequency generation shedding scheme. The PSFRR also recommends the continuance of primary frequency response after 2022-23, provided the cost benefit analysis shows this is in the best interest of consumers.

 The framework that AEMO considers to best allow it to respond to an interconnection loss during imports to SA (most likely during the morning and evening peaks when SA is importing) will be interesting. Short of continuing to limit imports into SA is likely to include industrial load shedding as well as contracting fast ramping generation assets through increase local Fast Frequency Response requirements (or 6 second Raise FCAS) or bi-lateral contracts with battery storage and gas reciprocating engines to cover the potential loss until other assets can be safely ramped up. If constraints on the interconnect persist this could also have implications for both congestion and MLF numbers in western Victoria – more congestion and lower MLFs (and eastern SA less congestion and higher MLFs) for current and newly connected wind and solar farms. For other frequency events we are likely to see all new solar and wind generation be placed into the existing generation shedding constraint to manage this risk which will likely persist for most of the daylight hours while rooftop is generating. The other very significant acknowledgement is that the CQ to SQ transfer is greater than 1,800MW and QNI is exporting at its stable limit which we have seen occur more and more often as NSW capacity declines then the system is unstable. Without significant intervention into upgrade to this section of the network the REZs north of and including Gladstone will essentially become constrained, meaning that only Darling Down REZ can effectively be developed (as Wide Bay has not indication of being developed at this stage) without upgrading other sections of the network outside the REZ.