ANALYSIS
By political editor Chris Uhlmann
Updated 17 minutes ago PHOTO: Just under half of South Australia's energy is generated by wind and solar. (ABC News)
The last time an entire state blacked out was on the night the Beatles arrived in Sydney in 1964.
So what happened in South Australia yesterday was rare and the repercussions could be vast.
The key question is whether that state's heavy reliance on wind turbines might have increased the risk of a state-wide blackout. More broadly, the event will supercharge concerns over how renewable energy is being integrated into a national grid that was not designed to cope with it.
Wind presents two problems. First, it is intermittent, so all of it has to be backed up by baseload power for those days when the wind does not blow.
The second is a diabolically tricky engineering problem. For an electricity network to function, demand and supply have to be kept in the perfect harmony of 50 hertz every second of every day. If the frequency gets out of tune, the system identifies a fault that could destroy it and that trips the shutdown switch.
This electrical harmony is called synchronous supply, and thermal power is very good at delivering it to the grid. SA power outage: how did it happen?
Wind power is asynchronous — its frequency fluctuates with the breeze and it has to be stabilised by the give and take of other sources of demand and supply.
South Australia has a unique energy mix, with 40 per cent of its electricity generated by wind and a high uptake of rooftop solar panels. The reduction in demand, driven by rooftop cells and coupled with the low price that subsidised wind farms can bid into the electricity market, has shut down all the states' coal-fired power plants. It now relies on three sources for power: wind, gas and coal-fired power imported from Victoria through two interconnectors that are its lifeline to the national electricity market.
The fragility of South Australia's electricity supply with the rise of renewables is an open secret. The 'non-credible event'
In February, the Australian Energy Market Operator and Electranet — the owner of South Australia's transmission services — released a report into the integration of that state's renewable energy into the grid. It said the system could operate securely and reliably with a high percentage of wind and rooftop photovoltaic generation, as long as one of the following two key factors apply:
The Heywood alternating current (AC) interconnector linking SA and Victoria is operational
Sufficient synchronous generation is connected and operating in the SA power system
"Overall, the studies highlight the increasing importance of the Heywood Interconnector in the secure and reliable operation of the SA power system," the report said.
It goes on to say, "In the event of a non-credible separation of SA from the remainder of the National Electricity Market, there is an increasing risk that the current Automatic Under Frequency Load Shedding scheme in SA will be unable to maintain SA frequency within the Frequency Operating Standards".
At 3:58pm yesterday there was what the report quaintly describes as a "non-credible event".
"A non-credible contingency event that trips both circuits of the Heywood Interconnector at times when there is high export from SA to Victoria is very unlikely, but would result in a rise in frequency within the SA power system and potentially lead to uncoordinated loss of generation," the report said.
"At present, there is no specific emergency control scheme in place to maintain frequency within the Frequency Operating Standards following such an event."
It could also be a problem if wind was supplying the bulk of South Australia's power and the rest was being imported from Victoria — meaning there was little or no synchronous generation inside South Australia.
Before the power outage yesterday, the wind was blowing a gale and the turbines were supplying 70 per cent of the state's power. Renewable transformation needs to be managed sensibly
Premier Jay Wetherill said the primary cause of the state-wide outage was the storm's destruction of transmission towers and that the National Electricity Market "did what it was supposed to do" — tripped the off switch to protect itself.
But what that switch was doing was protecting the east coast from the fluctuations of power in the west, it was not protecting South Australia.
Once the door to the east was shut, South Australia fell back on its own power supply, which, this report suggests, might by then have had a wildly fluctuating power supply and insufficient synchronous generation to keep it in check. That could explain why, region-by-region, the entire network shut itself down until the state went to black.
It might not be what happened but the report suggests this could have been the cause.
It is important to note that the Australian Energy Market Operator says the damage to the system was so catastrophic that it would have shut down no matter what the energy mix was in South Australia yesterday.
"Initial investigations have identified the root cause of the event is likely to be the multiple loss of 275 kilovolt (kV) power lines during severe storm activity in the state," it said in a statement.
"These transmission lines form part of the backbone of South Australia's power system and support supply and generation north of Adelaide,".
But the statement adds: "The reason why a cascading failure of the remainder of the South Australia network occurred is still to be identified and is subject to further investigation."
And that is the crucial question.
What is not in doubt is the next problem, rebooting the system. And that cannot be done with asynchronous power. To get the system online again, the energy market operator ordered the gas-fired power generator at Pelican Point to fire up, and then set about restarting the system bit by bit.
The blackout of an entire state is a major crisis. Politicians should know that you should never waste one.
Renewables are the future but, today, they present serious engineering problems. To deny that is to deny the science.
Those problems can be sorted in time, but rushing to a target to parade green credentials exposes the electricity network to a serious security risk and, in the long run, risks permanent reputational damage to the renewable energy cause.
The grid is being transformed, and that transformation needs to be managed sensibly, or the entire nation might go to black.
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PHOTO: Just under half of South Australia's energy is generated by wind and solar. (ABC News)
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