Aggregate Dispatch Error across all Semi-Scheduled units (NEM-wide) throughout Tuesday 13th February 2024

Tuesday 13th February 2024 was one of those days that has elicited many articles (with the ‘Significant Power System Event’ being analysed progressively on WattClarity).

Amongst the analysis was Allan’s very useful article ‘Victorian renewable generation on 13 February 2024: One picture and a thousand (sorry, many more) words’ – which separates out some of the different factors contributing to a very volatile aggregate (large scale) VRE profile in Victoria throughout the day.

One of the factors flagged was units being ‘Off Target’:

1)  Frequent readers here will remember many articles previously written using a metric we call ‘Raw Off-Target

… indeed, it’s one of many metrics we include for each individual DUID in the recently released GSD2023.

2)  A lead-in to the calculation of ‘Raw Off-Target’ is the metric AEMO defines as ‘Dispatch Error’.

Knowing that we have much still to explore about this day, and also that we’ll be reviewing more holistically as part of GenInsights Quarterly Update for 2024 Q1 in another 7 or 8 weeks,   I thought I would start here with this graphical summary of Aggregate Dispatch Error across all Semi-Scheduled units (NEM-wide) for all 288 dispatch intervals on Tuesday 13th February 2024:


There’s some pretty big numbers there (almost always collective under-performance … for logical reasons Allan’s explained):

1)   Even after leaving aside the 11:40 dispatch interval (which was skewed by the unexpected loss of 501MW from Stockyard Hill Wind Farm as part of Event 1).

2)  We’ll look forward to seeing where this day sits in relation to the ~90 others in Q1 when we get into analysis mode with respect to ‘Aggregate Raw Off-Target’ for Semi-Scheduled units as a focus for Appendix 3 inside of GenInsights Quarterly Update for 2024 Q1!

I’ve already noted in this article the question from Christiaan Zuur (at the CEC) and Allan O’Neil (valued guest author on WattClarity) over on LinkedIn here with respect to the material underperformance of VRE being a reason why AEMO needed to procure additional FCAS Raise Regulation Services for the day:


Keep in mind that Allan’s article only looked at Semi-Scheduled units inside of Victoria, whereas the chart above shows the net result of Semi-Scheduled units all the way across the NEM.

Long-term readers will remember that we asked the question ‘is the Semi-Scheduled category sustainable, or scalable?’ as Key Observation 13/22 within GenInsights21 (and then shared this with readers here on 9th March 2023).

That’s still a question that is echoing in our minds when we look at how this energy transition is unfolding … and the increasingly frequent large aggregate deviations away from target across all Semi-Scheduled units (which seem likely to require increasing volumes of FCAS procured to manage) is just one of the questions.

But we’ll leave this question here for now…

About the Author

Paul McArdle
One of three founders of Global-Roam back in 2000, Paul has been CEO of the company since that time. As an author on WattClarity, Paul's focus has been to help make the electricity market more understandable.

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