Frequency wobbles on Tuesday 17th June 2025

With respect to yesterday (Monday 16th June 2025) we have already:

1)  Noted a drop in frequency down below the lower bound of the NOFB shortly after 15:40 (NEM time); and

2)  Identified that the sloppy dispatch control of Semi-Scheduled VRE was one of the significant contributing variables.

 

So worth noting we’ve seen a couple near misses on the low end also today (Tuesday 17th June 2025) as noted in this graphical view:

2025-06-17-NEM-MainlandFrequency-drops

In the top chart, we show ~4 hours of frequency trace measured at 0.1 second cadence from our Brisbane office.  In this trace there are two instances whereby the frequency dropped towards the lower bound of the NOFB as follows:

 

In the 11:35 dispatch interval …

We see (in the second chart) some wobbles, with the lowest point being 49.868Hz at 11:31:20.608

 

Just after the 12:30 dispatch interval …

We see (in the third chart) a decline to a lowest point being 49.868Hz at 12:30:23.809

 

Since the (re)introduction of mandatory Primary Frequency Response, such wobbles initially became less frequent … but in recent times we’ve noticed more of these types of things.

Was this just because we’re looking closer, or is the frequency performance actually changing again?


About the Author

Paul McArdle
Paul was one of the founders of Global-Roam in February 2000. He is currently the CEO of the company and the principal author of WattClarity. Writing for WattClarity has become a natural extension of his work in understanding the electricity market, enabling him to lead the team in developing better software for clients. Before co-founding the company, Paul worked as a Mechanical Engineer for the Queensland Electricity Commission in the early 1990s. He also gained international experience in Japan, the United States, Canada, the UK, and Argentina as part of his ES Cornwall Memorial Scholarship.

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