The Impact of an Unexpected 500kV Transmission Line Outage
The unexpected failure of the 500kV Moorabool to Tarrone transmission line in South Western Victoria on 1st December has had significant ramifications for both the Portland Aluminium Smelter and also for South Australia, with a blackout. Because of the failure, there was:
- No power to the smelter with solidification of the metal occurring in Potline 1, which is an ongoing problem.
- No flow permitted across the Heywood Interconnector as this would have led to SA frequency instability.
- 220MW of load shedding required to rebalance the interconnector outage. The half hourly SA price at time ending 2pm was $13,416.92/MWh.
The situation was remedied after 4 hours. Unfortunately, there was insufficient available generation at the time to avoid load shedding. The cause of the transmission failure has been identified as a single phase to earth fault and a broken conductor cable o the transmission line was observed when the line was patrolled by helicopter.
This event can be understood in NemSight by plotting in the Time Machine module the flows across the Heywood interconnector, the SA price, SA demand.