On Wednesday afternoon 5th August 2026 the NEM experienced a significant drop in frequency (49.825Hz at 16:25:33.410).
This event seems different than ‘normal’.
Category no1) Historically, most frequency fluctuations originated from some form of trip:
(a) of large units or units on the generation side;
(b) or transmission
(c) or large loads (with a topical one being Data Centers) … in this case the frequency spikes
Category no2) In the NEM we’re increasingly seeing frequency disruptions stemming from collective under-performance of VRE (such as the examples tagged here)
Category no3) Yesterday appears to have been different from either category above … in that the root cause appears to have been some form of data glitch.
We are still exploring, more to be collated here…
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.
Supply fluctuated but was this to an equivalent extent as the recorded interconnector flows would suggest, or the noted demand change in NSW for the 16:25 interval?
The nadir we measured was shortly after 16:25: 49.825 Hz, at 16:25:33.
A first look at yesterday's major frequency event (and demand gyration in NSW) using 'next day public' data to look at Dispatch Error
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.
A sudden drop in NSW demand was followed by apparent recovery in the next interval.