A collation of articles pertaining to some larger disruptions in system frequency (such as outside of the Normal Operating Frequency Band – NOFB).
In this article we take the AEMO’s 4-second data and present this trace to start a broader sweep of system effects:, starting with System Frequency following trip of Loy Yang A1 near 4am on Monday 7th September 2026.
Yesterday (Tue 15th Sept 2026) we noticed Significant oscillations in ‘Market Demand’ in VIC, and also saw notable frequency fluctuations. We look at Dispatch Error.
The Stanwell Power Station coal units are some of the best performing coal units in the NEM … which is what made this full-load trip on Thursday 27th August 2026 just prior to 12:00 unusual.
In this 6th article relating to the data glitch triggered frequency excursion on Wednesday 5th August 2026, we take another look at interconnectors, and start compiling a sequence of events.
A much more 'traditional' drop in frequency on Friday morning 7th August 2026 (compared to the stranger-but-deeper drop on Wednesday 5th August 2026), with Friday's following a coal unit trip
We don’t know what happened, yet - just wanted to flag the significant frequency drop here this evening so readers don’t think it was ‘just’ a data glitch.
I can’t recall when we last saw a trip as large as the 620MW trip that occurred just prior to 08:05 on Sunday morning 26th July 2026
At 07:56:24 local time on Wednesday 22nd July 2026 in PJM, the frequency spiked to ~60.1Hz in response to a ~3,000MW sudden drop in demand.
The team noted this yesterday (Friday 22nd May 2026) morning … so here’s a quick note to record the sustained period of mild frequency sag.
We noticed the debilitating uncertainty that the folks at Currently Speaking suffer from (and wrote about here), so we thought we’d take pity on them with this quick note (about BW01 trip this morning).
We start with this unbundled listing of 402 discrete stories about the performance of Semi-Scheduled units (115 solar & 86 wind) units on Friday 10th and Saturday 11th April with the frequency spikes.
Presenting this single image which summarises the sequence of events (for a number of Semi-Scheduled units) over three dispatch intervals across the pair of frequency spikes (on Fri 10th and Sat 11th April 2026).
Next layer of the onion, in investigating the eerily similar (and closely related) frequency spikes outside the NOFB on Friday 10th April 2026 and Saturday 11th April 2026.
With the advantage of 'next day public' data we look at 'Dispatch Error' (for all 201 Semi-Scheduled units) at 14:20 on Saturday 11th April 2026 to see what drove the frequency spike outside of the NOFB. There was a big imbalance...
A first look at a frequency spike (outside the NOFB) focused in the 14:20 (excursion) and 14:25 (recovery) dispatch intervals NEM time on Saturday 11th April 2026 (an almost identical event to what happened the day before).
With the advantage of 'next day public' data we look at 'Dispatch Error' at 10:30 and 10:35 on Friday 10th April 2026 to see what drove the frequency spike outside of the NOFB.
Occurring just after the frequency spike on Friday 10th April 2026 were these 4 large Non-Conformances noted at 4 x Wind Farms in Victoria.
A first look at a frequency spike (outside the NOFB) focused in the 10:30 (excursion) and 10:35 (recovery) dispatch intervals NEM time on Friday 10th April 2026.
We take a first look at Aggregate Dispatch Error (by Fuel Type, NEM-wide) in relation to the Frequency Drop following trip of Kogan Creek early Thursday morning 2nd April 2026.
Following the (~full load) trip of KPP_1 this morning (Thu 2nd April 2026) we take a first look at frequency response.