The South Australia blackout was sparked after a severe storm caused wind power to disconnect from the electricity network, a new report has found.
The Australian Energy Market Operator released a preliminary report today into how the electricity supply was cut off last Wednesday.
It found that high winds, thunderstorms, lightning strikes, hail and heavy rainfall caused problems with the electricity transmission system. This includes the failure of three major transmission lines north of Adelaide in the space of 12 seconds.
This caused system instability with “significant voltage dips and loss of load,” the report said.
Although power was initially maintained, at 4.18pm (AEST) multiple faults in a short period of time caused 315 MW of wind power to disconnect.
To make up the shortfall, the network tried to get more power via the Heywood interconnector, which provides SA with electricity from Victoria. But this caused the interconnector to overload.
It took “less than half a second” for this to trigger an “automatic-protection mechanism” that cut off the power in SA in order to protect the interconnector from being damaged.
While the event was triggered by extreme weather, the AEMO said it would undertake a thorough investigation into how each component of the electricity system responded.
“Insufficient analysis has presently been undertaken to determine if everything operated as designed during the event,” the report noted.
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The AEMO said it would continue to analyse what happened on September 28 and would provide a further update on October 19.
A detailed report on the blackout, including recommendations, may take up to six months to complete.
Just before the blackout, almost half of the state’s power was being supplied by wind farms (883 MW), with the rest coming from thermal (330MW) and electricity imports from Victoria through both the Heywood Interconnector and Murraylink DC cable (613MW).
In the seconds before the blackout, the network experienced a reduction in power from six wind farms including Hornsdale and Snowtown.
“Each reduction coincided with a drop in voltage observed at the wind farms’ connection points,” the report said.
The network tried to increase the power it was getting from the interconnector to over 850MW but the system was only designed to deliver a maximum of 600MW. This is what looks to have tripped the “Black System”.
The report revealed that power was restored after AEMO asked ElectraNet, who owns the transmission network, to gradually power up the interconnector to Adelaide and start the gas-fired Torrens Island Power Station, which had been offline due to a planned outage.
Adelaide got its electricity back about 7pm and by midnight, 80-90 per cent of the power that could be restored had been.
But the loss of three of the four main transmission lines north of Adelaide effectively cut the electricity grid in two, isolating the north of the state, where power could not be restored.
Technicians needed to inspect the fourth line to make sure it was okay before electricity was finally switched back on at 12.15pm on Thursday. However, supply remains constrained to some parts of the north.
‘NOT A RENEWABLE ENERGY EVENT’
In response to the report, South Australia Premier Jay Weatherill said the state-wide blackout was caused by a severe weather event, not a renewable energy event.
“South Australia hasn’t seen a storm like last week’s in living memory,” Mr Weatherill said on Wednesday.
“Those images of transmission lines bent over showed just how powerful the wind was.”
He accused Prime Minister Malcolm Turnbull of politicking by blaming SA’s embarrassing state-wide blackout on renewable energy.
“Malcolm Turnbull, our PM, took the first opportunity to lecture South Australians about the dangers of renewable energy, and for the Labor states in promoting unrealistic renewable energy targets,” he told reporters on Wednesday.
“Now this was information that was made … in contradiction of the oral advice that we were receiving from the Australian Energy Market Operator.
“The PM was fearful that he would be blamed for a national electricity market that caused a blackout.
“The PM was fearful that he would be blamed by the right-wing of his party for pushing into renewable energy when he knows that he leads a party which is dominated by coal interests.
“It’s deeply disappointing that we do not have the national leadership which is necessary to deal with this and other issues.”
But Mr Turnbull told reporters Mr Weatherill still had a case to answer to “keep the lights on” in his state.
“What we need to do across all levels of government is this – we have to deliver energy security. Rule one – keep the lights on,” he said.
“Second, we have to ensure that energy is affordable. SA has the highest wholesale energy costs in Australia.
“So that is a problem for SA and the government, Mr Weatherill has to answer for that.”
Mr Weatherill said a meeting of the nation’s energy ministers in Melbourne on Friday will be a chance to discuss the blackout and prevent a reccurence.
The Australian Conservation Foundation welcomed the report and said it highlighted the need for a national plan to guide the country’s transition to clean energy.
“At present what is clear is the transition to clean renewable energy remains central to Australia’s efforts to address global warming and it also offers enormous opportunities for jobs and investment,” ACF’s Suzanne Harter said.
She said last week’s events should not scare Australians but prompt them to better understand what’s required to transition to clean energy.
“Let’s not forget, Australia’s reliance on coal for electricity is fuelling climate change, which means we can expect more extreme heat, more flooding and more big storms,” she said.
“Friday’s meeting of federal and state energy ministers should work towards a coordinated national plan to transform Australia’s energy system.”
At the height of the storms last Wednesday, 23 transmission towers were torn from the ground in SA’s mid north, plunging 1.7 million people into darkness. Power returned to much of candlelit Adelaide within hours but for some in regional areas the blackout lasted far longer.
On Tuesday, Mr Weatherill announced an independent inquiry into the storms and the widespread power outage they caused.
“South Australians responded with a collective resolve that should make us all proud,” Mr Weatherill said.
“Nevertheless, as a government there are always lessons that can be learned from an extreme weather event such as this.
“So it’s important there’s a thorough, independent review.”
Led by former SA Police Commissioner Gary Burns, the inquiry will focus on SA’s preparedness for blackout that sparked a nationwide debate over energy security.
— With AAP