Challenges with a global-only FCAS requirement

The very fast (VF) 1-Second FCAS markets started on 9th October 2023.

Yesterday we noted the cap on the requirement for the raise service would be increased on the 6th of November.  This is part of a transitional arrangement to manage required levels within existing capacity.

Another aspect of the transitional arrangements is that we are starting off with a single NEM-wide requirement for 1-sec raise and for 1-sec lower. AEMO note that “Increments to the amounts required for islanded NEM regions will be made separately, recognising that the volume of VF FCAS registered to support local versus global requirements may differ.”

Coincidentally, also yesterday, two keen-eyed ez2view users directed our awareness to the current Basslink outage.

In the chart of the flows on Basslink over the last week we can see flow has been fixed at 0 MW since the morning of 28 October 2023.

The Basslink outage is managed with the constraint set ‘I-BL-ZERO’. It is currently scheduled to end on the 2nd November 1t 17:00. The total duration is anticipated to be a total time of 5 days, 11 hours and 30 minutes.

With no power able to flow from VIC to TAS or from TAS to VIC it seems clear that a contingency event on the mainland couldn’t be addressed by units in TAS, and vice versa.

Yet, with the existing global 1-sec FCAS requirement for raise and lower, prices remain locked in all NEM regions regardless of Basslink, and often set by a single unit for all regions (bottom right panel).

Enabled volumes appear to be unhindered (bottom left showing a unit in TAS enabled for the raise service while Basslink is out).

We wonder whether the need for local VF FCAS requirements or the need for outage-related constraints has arrived.


Basslink outage VFFCAS




An additional market notice published on the 31st of October describes constraint changes and additions to come on the 6th of November. Notably, the new changes will move the configuration towards the usual FCAS constraint setup where the Basslink state is accounted-for (Basslink In, Basskink Out, and Basslink In But Possibly Limited).  For further details, including the market notice text, readers are directed to the updated original article: Very Fast Raise Service to be Expanded.


About the Author

Linton Corbet
Linton joined Global-Roam as a software engineer and market analyst in August 2020. Prior to joining us, he worked with the AEMO for 7 years, and before that, as an air quality scientist.

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