Load shedding typically occurs when an energy provider begins rolling black outs to prevent damage to the electricity grid.
In total, just over 100,000 homes were left without power for Saturday evening throughout the Perth metropolitan area, with the blackouts stretching as far as Geraldton and Kalgoorlie-Boulder.
Western Power said this accounted for about 10 per cent of their customer base.
The blackout was one of the most widespread electrical faults in WA in about five years, and Western Power asset operations executive manager Dave Fyfe said all customers were back online by about 11.30pm, and the network had responded “as it should”.
“It’s not common by any stretch but it can happen. The network responded how we wanted it to, the network remains stable and safe,” he said.
“We worked out the cause fairly quickly… we lost a large generator that connects to the network. Any sudden loss of a large amount of generation has an impact on the network.”
State opposition leader Liza Harvey said the incident was a “disturbing omen” for the power supply in Western Australia.
“Premier Mark McGowan needs to immediately explain why 100,000 Western Australia homes suffered blackouts and what his government was doing to invest in long-term energy security,” she said.
“Mr McGowan needs to enlighten us as to why was there insufficient back-up generation available, why system frequency could not be maintained and why the plant failed, despite a recent performance audit.
“This widespread blackout is a disturbing omen, especially given the national energy operator AEMO warned the McGowan Labor Government that blackouts will become commonplace without substantial and immediate investment.”
The Kwinana facility is privately owned and a trusted source for Western Power, and AEMO WA executive general manager Cameron Perotte said he had received information about what possibly caused the generator to fail.
“What we’ve been told … was that it was a generator bearing issue – the generator sits and rotates and it needs a bearing to sit and rotate. One of those had an issue and that’s unfortunately now resulted in that generator tripping off quite quickly.
“We run what’s called ancillary services, special reserves – they’re available for when a large generator falls off.
“We had the required reserves on last night, we just happened to lose the largest generator and then a couple of other generators fell off at the same time and as a result of that our reserves weren’t sufficient.
“These events do happen, they’re not common – in was about five years ago that the last one occurred.”
Western Power later apologised for the interruption, and said no lasting damage had been done to the network.
“There is no physical damage to the network which means that restoration will be quick once we have worked with AEMO to formulate a dispatch plan for generation, to restore frequency balance through the grid,” a statement said.
“We apologise for the outage and are working as quickly as possible to restore power with the relevant parties.”
The AEMO has previously warned the uptake of solar power in WA was threatening the stability of the state’s electricity grid, and said if this was to continue, it could force rolling power cuts to avoid the grid overloading.
The state government was contacted for comment.
Hannah Barry is a journalist for WAtoday.