The multi-region islanding event on Saturday 25th August was a very rare event – perhaps the only one’s that occurred in the history of the NEM. It has generated plenty of questions – and driven our analysis further. We share some more observations here, and keenly await the draft AEMO report.
Automatic Under Frequency Load Shedding (AUFLS)
Following on from Saturday’s islanding event, we use our current interest in AEMO’s 4-second SCADA data to prove a little more…
Both the QNI and the Heywood interconnectors tripped around the same time on Saturday 25th August 2018 (not apparent at this time which one was first, and why), leading to both QLD and SA regions being separately islanded from the rest of the mainland NEM. This also contributed to over 1,000MW of load shedding in NSW and VIC, and presumably some frequency excursions in QLD and SA.
The East Coast power system of Australia has the worst frequency regulation in the developed world. This puts the system at risk whenever an event occurs which requires the generators to respond quickly – they can’t respond quickly if they have to wait for the system frequency to go outside its control system dead band.
AEMO issues a Market Notice for a “High Impact Outage” – a term not used since 2012.