AEMO incident report released, on Frequency Spike due to Self-Forecast Vendor glitch (19th August 2025)
About the AEMO’s Reviewable Operating Incident Report ‘Self-forecasting errors and frequency excursion on 19 August 2025’.
2025-08-19-SelfForecastGlitch-drivesFreq
Here’s a subset of articles pertaining to events of Tuesday 19th August 2025.
On this day …
1) There was a large frequency spike across the NEM that was caused by a data glitch at one particular vendor of self-forecasts:
(a) In this category we have collated a couple of articles about the glitch;
(b) But note that there are more articles here about the large frequency spike across the NEM
i. lasting ~25 minutes
ii. and above the upper bound of the Normal Operating Frequency Band in the middle of the day.
2) However note that there’s more articles that are more broadly focused on 19th August 2025.
AEMO declares Scheduling Error – related to the ‘Self-forecast vendor issue’ experienced on 19th August 2025
Last week (on Thursday 27th November) the AEMO made a Scheduling Error Declaration about the sizeable glitch in a particular self-forecast vendor that delivered phantom production on Tuesday 19th August 2025 and a large frequency spike.
AEMO frequency monitoring report provides some details of frequency event (due to self-forecast glitch) on 19th August 2025
Adding to the list of articles we've collated about the frequency disturbance on Tuesday 19th August 2025, we're copying in what AEMO published in its 2025 Q3 monitoring report about the glitch.
On 27th October 2025, AEMO declared Scheduling Error #73 (with respect to 19th August 2025)
A belated and back-dated article, dated for 27th October 2025, which was when the AEMO declared a ‘Scheduling Error’ – Incident #73 with respect to 19th August 2025
High level view of some contributing factors to 19 August frequency spike
Among other aspects, a large dip in solar UIGF aligns with the frequency deviation observed on 19th August 2025.
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.