Frequency drop on Thursday evening 11th Sept 2025 with Tallawarra B trip
A quick article to explore a frequency drop on Thursday evening 11th September 2025.
frequency disruption
A collation of articles pertaining to some larger disruptions in system frequency (such as outside of the Normal Operating Frequency Band – NOFB).
Highlighting particular (frequency and/or AggROT) events through 2024 and 2025
In this article, we tie together various events since 1st January 2024 that featured either System Frequency outside the NOFB and large AggROT for Semi-Scheduled assets.
Looking more at (commissioning) operations at Waratah BESS through August 2025
In this article we take a look at operations of Waratah BESS through August 2025 - including some large Dispatch Errors on several days: (a) including Fri 29th Aug 2025, and how WTAH1 apparently...
More about that decay of mainland frequency at lunchtime on Friday 29th August 2025 (i.e. Part 2)
Taking a second look at the midday decay of mainland frequency on Friday 29th August 2025.
Mainland frequency drop with Loy Yang A1 trip on Saturday evening 30th August 2025
On Saturday evening 30th August 2025 there was a trip (and then subsequent recovery) of the Loy Yang A1 unit - we take a look at frequency change.
Decay of mainland frequency at lunchtime on Friday 29th August 2025
As another case of frequency disruption on the mainland grid, we spotted this trend occurring just before midday on Friday 29th August 2025.
Tasmanian demand drop on 16 August 2025 – part 2
We follow on from A 292MW drop in "Market Demand" in Tasmania, on Saturday 16th August 2025 enlisting this "Part 2" to understand the sequence of events using 4-second data.
Frequency change with Yallourn unit 2 trip
We assess whether the trip at Yallourn 2 on 26 August 2025 was large enough to drive a frequency disturbance.
Peeling the onion a little more – Solar Farm performance on Tuesday 19th August 2025, with the frequency spike to 50.2Hz
As the 5th article in an evolving series that progressively explores the (apparent self-forecasting glitch and) frequency spike on Tuesday 19th August 2025, we take an early look at Solar Farm performance.
An updated tabular list of instances of large AggROT across Semi-Scheduled units
Earlier today we trended the incidence of large Aggregate Raw Off-Target across all Semi-Scheduled units. In this updated tabulated list, we list each of the largest instances from January 2024 to June 2025.
Three broader questions (re)triggered by the Frequency Spike on Tuesday 19th August 2025
The (concerning) frequency spike across the NEM in the middle of the day (Tuesday 19th August 2025) has triggered many proximate questions - understandable - but also has raised these 3 Broader Questions.
Mainland Frequency Spikes to 50.2 on Tue 19th August 2025
On Tuesday the 19th of August between 11:45 and 12:20 there was a significant frequency deviation on the mainland.
Loy Yang A2 apparent trip from 443MW on Wednesday 25th June 2025
A very short midday article on Wednesday 25th June 2025 noting this apparent trip of LYA2 unit from 443MW just prior to 11:31 (NEM time).
Frequency wobbles on Tuesday 17th June 2025
A quick look at two particular instances of (relatively small) frequency disruption on Tuesday 17th June 2025.
Which units show large positive Dispatch Error for 15:40 on Monday 16th June 2025
Following on from Linton's article (about the frequency drop at 15:40 on Monday 16th June 2025) we take a look at the largest harmful Dispatch Errors across the full fleet of units ... and...
Drop in mainland frequency on 16 June 2025
In reviewing system frequency on the 16th of June, 2025, we observed a drop that reached below the NOFB.
Sharp drop in frequency on Friday morning 13th June 2025, with trip at Newport Power Station
I’ve not yet had time to fully investigate, but thought it worth recording the sharp drop in frequency that appears to have occurred shortly after 07:30 NEM time on Friday 13th June 2025.
A quick look at system frequency, with 2 x coal units offline overnight into Saturday 31st May 2025
It’s fitting to book-end the week with a look at frequency performance overnight (into Saturday 31st May 2025) with two coal unit outages in NSW overnight to see what happened in terms of more...
Poor dispatch performance of VRE (collectively) on Monday 26th May 2025 sufficiently large to drive frequency outside of NOFB
Prior to the Brisbane session of the Nelson Review Panel (on Thu 29th May 2025) we take a look at Dispatch Error in the 16:15 dispatch interval on Monday 26th May 2025 to see...
Drop in mainland system frequency on 26 May 2025
The measurements indicated frequency ducked just below the NOFB briefly, reaching 49.843 Hz.