One of our team members posted a snapshot of the ‘Unit Dashboard’ widget in ez2view on an internal Slack channel yesterday, looking at the WELNSF1 unit with real time data, pointing out what appeared to be some form of glitch in SCADA data through the day.

Now with the benefit of ‘next day public’ data we can see a fuller picture – in this snapshot looking back 4 days from the 13:20 dispatch interval (NEM time) on Sunday 24th May 2026:

Briefly, I have highlighted three time periods that particularly jump out immediately:

Focus period #1

Yesterday (Saturday 23rd May 2026) we saw an 8-hour period (from 12:05 to 22:00 …yep, long after the sun’s gone down) where the SCADA reading for FinalMW appears to be stuck at 208MW.

… we’ll call this suspect glitch #1A

I’ve focused the table on the right at the 21:00 dispatch interval (NEM time) which is the first one during which the Availability of the unit drops to 0MW.

1)  Now, I’ve not checked exactly when sunset would have been on that site, but let’s assume it’s somewhere around 17:00

2)  So that means that the UIGF for the plant (which was coming from AEMO’s ASEFS system through the period) was also stuck at 208MW.

… we’ll call this suspect glitch #1B

Focus period #2

The day beforehand (Friday 22nd May 2026) we see a morning period:

1)  that begins at 09:15 (NEM time):

(a)  when the UIGF for the plant jumps from a low 11MW to 121MW (whilst LOCL and ELAV are both still low)

(b)  and runs through until 11:05 when a rebid is submitted with rebid reason ‘Availability adj due to plant related issues SL’ at which point the MaxAvail is dropped to 15MW to drop the AvailGen from the unit feeding into NEMDE

2)  During this period (i.e. 09:05 to 11:00) the output from the unit trends through at ~10MW … which means a consistent Dispatch Error over that period of approximately +100MW

3)  So it seems that, by chance, we’ve bumped into one of the contributors of the ‘… sustained period of Frequency Sag through Friday morning 22nd May 2026’!

Focus period #3

Back on Thursday 21st May 2026, we’ve also noted a period through the day of consistent under-performance relative to Target.