My notice of this wasn’t an ez2view alarm or other software – at 14:08 AEDT (13:08 NEM time) my evaporative aircon tripped off. The last time this happened was on 31 January 2020 when a storm destroyed a section of the 500kV transmission line linking Victoria and South Australia – so I wondered if there’d been some sort of power system event. Indeed.
Based on AEMO’s market notice, the triggering event may have been a trip of two parallel lines linking Moorabool near Geelong with Sydenham in the west of Melbourne.
These are a major section of the 500kV transmission ring around the greater Melbourne area, so it’s not surprising a trip of those lines would have significant impacts.
The Bureau’s radar indicates there may well have been a storm and lightning in the vicinity of these lines at the time:
You might expect an event like this to crash system frequency. As confirmation, I’ve stolen a helpfully provided high-res frequency trace from (of all places) Facebook:
The apparent nadir at 49.65 Hz isn’t low enough to trigger under-frequency load shedding, but other factors associated with the event may well have “shaken off” some of the lost load “in excess of 1,000 MW” referred to in AEMO’s market notice. My aircon for one.
In response to that loss of generation, we see hydro and fast-start gas generators ramping up after the LYA trip. Also note a few windfarms in the area of the tripped lines seem to gone offline as well:
Big flows south out of New South Wales on top of the Victorian hydro and Snowy’s Murray stations. In fact it looks like flows at this particular time are exceeding secure limits, based on the number of violating constraints about an hour post-event:
The spot price remains at the Market Price Cap of $16,600/MWh, and AEMO has begun Reliability and Emergency Reserve Trader (RERT) negotiations as I post – more to come on this event undoubtedly … but that’s all for now.
About our Guest Author
|Allan O’Neil has worked in Australia’s wholesale energy markets since their creation in the mid-1990’s, in trading, risk management, forecasting and analytical roles with major NEM electricity and gas retail and generation companies.
He is now an independent energy markets consultant, working with clients on projects across a spectrum of wholesale, retail, electricity and gas issues.
You can view Allan’s LinkedIn profile here.
Allan will be occasionally reviewing market events here on WattClarity
Allan has also begun providing an on-site educational service covering how spot prices are set in the NEM, and other important aspects of the physical electricity market – further details here.