From Fri 31 Jan 2020 to Mon 17 Feb 2020, South Australia was separated from the NEM following the collapse of six towers on the double circuit 500 kV lines to the east of the Portland Aluminium Smelter (more details here at Wattclarity. During this period AEMO were able to supply the Portland Smelter using the Mortlake Gas Turbines registered in the Victorian Region.
Also during this period, the usual Frequency Control and Ancillary Services (FCAS) provided to SA from the Eastern NEM were not accessible, thereby limiting their provision to the SA FCAS providers. As a result, it was a lucrative period for FCAS providers, particular the three SA Battery Projects at Hornsdale, Dalrymple and Lake Bonney.
In summary, the FCAS services provided by the three SA Battery Projects derived $41.82 Million, made up of $25.36 M, $10.21 M and $6.25 M at Hornsdale, Dalrymple and Lake Bonney respectively. Energy Revenues for the three batteries was $72 k. Impressively, the Hornsdale Battery was able to earn $25.36 M for FCAS services for an energy cost (battery charging) of only $1,605 . The details for each battery are shown in the graphs below, noting the logarithmic scales.
For those wanting to explore and understand FCAS more, particularly in the relation to the SA 'Islanding' Event, Wattclarity published two excellent articles that are highly recommended reading: