Millmerran unit 2 offline on unplanned outage – Wednesday 21st August 2024

Reader Beware … just because you’re reading more about coal unit outages here in recent days, it does not necessarily mean that these outages are happening more frequently!

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As noted in yesterday evening’s article about the unplanned outage at Loy Yang A1 (more on that later, time permitting), we have several reasons to be publishing a series of these ‘coal unit outage’ articles in recent days … not the least of which are to help several ez2view clients to understand how to do this type of alerting and analysis themselves.

This morning we noticed that Millmerran Unit 2 came offline … again through our ‘any coal unit switches off’ configured alert in the Notifications widget in ez2view that handily sends a few of us an email:

Worth noting in this article that this alert was triggered by ez2view at ~08:31 … so just at the end of the 08:30 dispatch interval when AEMO does the ‘SCADA snapshot’ process to produce what’s alternatively called:

• FinalMW for 08:30
• InitialMW for 08:35

What this means is that the know the unit was offline by ~08:29:40 (i.e. when the ‘SCADA snapshot’ process was run … more on that in a subsequent article).

Briefly, let’s look at a couple other data sets…

(A)  Unit Dashboard widget

In the ‘Unit Dashboard’ widget in ez2view, we see the following display:

(B)  Not a planned outage

Note that I have not included a snapshot of the ‘Generator Outages’ widget here … that’s:

1)  Because it’s going to look largely the same as it did at the time of yesterday evening’s article;

2)  Which happens because the MT PASA DUID Availability data set is only updated several times through ‘sunlight hours’ 6 days per week (i.e. shortly after 09:00, 12:00, 15:00 and 18:00) … and so, at the time of the coal unit outage, there’d been no update since yesterday, and the image there showed no planned outage in the next couple weeks.

(C)  Wait till 04:00 tomorrow for rebid reasons

Likewise, we need to wait until after 04:00 tomorrow for the ‘Next Day Public’ data dump that would help indicate how the generator responds as the unit trips … which (e.g. in the rebid reasons) might give some clues as to why the unit has come offline.

So no value in looking too much at the ‘Bids & Offers’ widget yet.

(D)  Mainland Frequency

What we can do is include this snapshot of System Frequency on the mainland, which shows a smaller drop in frequency compared to here for LYA4 on Wed 14th Aug and  TNPS1 on Mon 19th Aug (in part because of a smaller size instantaneous reduction):

Similar (but not quite the same) as yesterday, the frequency recovery will presumably have been because of Primary Frequency Response augmenting Regulation FCAS (though perhaps not Contingency Raise FCAS  in this case).