This article’s just a short one, for a change.
As noted on this Glossary Page, there are several different types of ‘Gate Closure’ applicable to operations in Australia’s National Electricity Market (NEM):
1) Whilst it’s fairly widely understood (even across the broader suite of NEM observers) that bid bands are set at 12:30 (NEM time) on the prior day for each Market Day,
2) It’s only a smaller subset of people who are on top of the nuances of Gate Closure #2:
(a) Which relates to the specific timing of when volumes in those bid bands can be changed; and
(b) Which is the subject of this article.
3) It’s an even smaller subset that think about Gate Closure #3 (but that deserves its own article).
The topic of ‘Gate Closure #2’ has come up in several conversations recently (including in a few recent training sessions for new starters for our ez2view software), so I undertook to have a look* to see how the timing was trending.
* Full Disclosure – the SQL and EMMS knowledge to produce this query is well beyond my capabilities, so others in the team quickly extracted the data for me.
A long-range trend of Gate Closure #2
Starting back in 2010 we queried our internal EMMS to see what we could find, for each day over ~15 years, at the minimum time (prior to the end of a Dispatch Interval) in which a participant could submit a rebid and have it accepted* for the immediately following Dispatch Interval.
* there’s plenty of rebids that are ‘too late’, in which case they might miss the price spike the participant is trying to rebid into.
Quick notes:
1) Due to the complexity of the underlying data, and hence the query, there’s a few aberrations in the data that was extracted
… because we only ran this query out of interest, and as the picture above provides the overall message, we did not invest the time to get to the bottom of these aberrations.
2) There’s clearly a big improvement made by AEMO towards the end of 2021 :
(a) which we noticed at the time and reported in the article ‘Two recent improvements (in late November 2021) by AEMO in the dispatch process’.
(b) this (i.e. allowing receipt of rebids closer to the end of the dispatch interval) will improve the efficiency of dispatch outcomes in the NEM.
3) There’s also (potentially) something also notable happening more recently?
Most recent 3 years
Zooming into the most recent 3 years (and hence scaling down the y-axis) we see the following:
Eyeballing this chart (for which I’ve added a 30-day rolling average), it does appear that there might have been a small increase in Gate Closure #2 time from 2023 (when it was ~12 seconds) into 2024 (slight increase to ~13 seconds). We’ve not explored further than this at this point.
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