At 9pm on Tuesday, more than 470,000 customers were still without power across the state, the department said – down from the day’s peak outages of more than 530,000.
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The Loy Yang A power station was in the process of being reconnected to the grid, it said.
On a day of wild weather, an out-of-control bushfire in the Grampians National Park in the state’s west had reached the town of Pomonal, emergency services said. Reports indicate that 25 to 30 houses have been lost in the Pomonal area as has the town’s historic church. The Country Fire Authority late Tuesday also confirmed that five members had sustained minor injuries at Pomonal.
Meanwhile, the heavy storm that swept across the state lashed parts of Melbourne with hail in the afternoon.
The energy market operator on Tuesday said the destruction of part of the 500-kilovolt transmission line at Anakie west of Melbourne during heavy storms triggered a domino effect across the state’s energy network.
It took 1000 megawatts out of the system and tripped all four units at the coal-fired Loy Yang A, forcing them to shut down – which removed 2.3 gigawatts of generation from the network.
The spot price of electricity in the state then soared above $16,000 per megawatt hour – at the same time it was $93 per megawatt hour in NSW – as Victoria was forced to import from other states.
In an effort to keep the grid stable, AEMO also began “load shedding” – forcing blackouts on parts of the network.
About 90,000 customers were affected by the load-shedding disruption, which was ended by 4pm Tuesday.
However, the state’s distribution companies reported that 500,000 people remained without electricity.
Companies including AusNet, Powercor and Jemena were still assessing the damage on Tuesday night and trying to restore electricity.
On Facebook, Citipower and Powercor Australia said a “a combination of extreme temperatures, strong winds and thousands of lightning strikes are causing damage to poles, wires and other electrical infrastructure”.
D’Ambrosio said on Tuesday she had met the head of AEMO to discuss the situation.
“One unit at Loy Yang A power station has come back online and as a result forced load shedding is no longer required to maintain grid stability,” she said.
“The situation remains volatile. I’ll continue to provide updates as they become available.
“We are working with AEMO and relevant authorities to get Victorians back online as quickly as possible and we want to thank those impacted for their patience.”
D’Ambrosio said on X later on Tuesday night that power line companies would work through the night to assess damage to sub transmission lines, zone sub-stations and feeders.
“We hope to see more customers reconnected overnight with priority given to power dependent customers,” she said.
An AGL spokesperson said work was under way to return its units to service.
“This will take place over the next few hours in line with our safety and operational protocols, and as associated transmission line issues are resolved,” the spokesperson said.
AGL expected three units to be brought back progressively on Tuesday night, with one unit to remain offline.
In a statement, AEMO said it was investigating the cause of the event in which 500-kilovolt transmission lines from Moorabool to Sydenham were tripped and multiple generators had been disconnected from the grid.
“Controlled load shedding is a mechanism AEMO uses as an absolute last resort to protect system security and prevent long-term damage to system infrastructure,” the operator said.
“These power outages are due to high temperatures, strong winds and lightning causing damage to the electricity network.
“Crews are actively working to restore power to these impacted areas, clearing vegetation to make the areas safe before replacing poles and mending fallen powerlines.”
The thunderstorm that hit parts of Melbourne on Tuesday afternoon brought hail as it travelled south-east across the city. Residents in Highett, Altona North and Hampton were among those who reported hail as big as golf balls shortly after 2pm.
As the storm battered the city, the temperature at Melbourne’s Olympic Park dropped from a peak of 35.8 degrees at 1.30pm to 28.2 degrees by 3.26pm.
Metro Trains advised people to defer travel in Melbourne on Tuesday afternoon, with services impacted on sections of the Belgrave, Craigieburn, Cranbourne, Frankston, Glen Waverley and Pakenham lines.
Lisa Zembrodt, principal and senior director at Schneider Electric, said Tuesday had shown the electricity grid was not ready for more frequent and damaging storms driven by climate change.
“There’s a lot of work to do to get us where we need to be for the grid to be more resilient for customers,” she said.
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Zembrodt said community batteries, microgrids and more widespread solar panels were options to improve the system, along with incentives to encourage businesses and homes to use their appliances during parts of the day when the network was less congested.
Opposition energy spokesman David Davis said a key focus over the next week would be to understand the full sequence of events.
“A key responsibility of government is to ensure a reliable, secure and affordable power supply is available,” he said.
