Suspect SCADA drove data discrepancy on 9th December 2024

Following our reading of the final report into 13 February 2024, we happened to glance at the current list of declared scheduling errors.

The latest declared scheduling error relates to what we suspected was as a ‘data glitch’ on the 9th of December 2024.

At the time we observed ‘Market Demand’ in Victoria ramps by 903MW in 10 minutes, on Monday 9th December 2024 and then, soon after, an apparent correction in  ‘‘Market Demand’ in Victoria (apparently!) drops 3,100MW in 5 minutes, on Monday 9th December 2024 … a data glitch?!.

The incident description in the declaration provides us with a glimpse into the underlying cause:

“From 1325 hrs to 1450 hrs on 09/12/2024, the SCADA data for the Guthega unit was flagged as suspect in EMS. Under this circumstance, NEM demand was incorrectly calculated and it led to erroneous interconnector flows and dispatch outcomes. During the impacted period, the total difference in demand was approximately 6,125 MWh.”

Using ez2view’s Trends, also available in NEMreview v7 online, we can review market demand and prices during the event:

The description references interconnector flows. To conclude, here’s a chart of target flows for VNI (Vic to New South Wales) over that same timeframe:

PS1The interconnector issue shows up most prominently at the end of the 14:40 interval. The target flow was -1,255 MW but the metered flow was 1,595 MW.  That’s 2,850 MW different from the dispatch expectation.