A new report has revealed why South Australia’s wind farms didn’t ride-through the storms
A KEY energy official has conceded that more could have been done to prevent last month’s statewide blackout as a new report reveals the failure of SA wind farms to deal with network faults was greater than first thought.
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A KEY energy official has conceded that more could have been done to prevent last month’s statewide blackout as a new report reveals the failure of SA wind farms to deal with network faults was greater than first thought.
An updated report by the Australian Energy Market Operator found nine of the 13 wind farms — not six as originally thought — providing power to SA reduced or cut supply after a series of voltage disturbances during the storm on September 28.
The sudden and “large deficit of supply caused the system to collapse.”
The loss of that 445MW of wind power generation from the shutdowns led to a huge demand on the interconnector, which tripped, before a loss of frequency in SA and total blackout.
The report indicated an expectation that all generators should have been able to ride through the transmission faults caused by the storm.
The South Australian government has drawn criticism that its greater reliance on renewables has reduced the state’s energy security.
But Treasurer Tom Koutsantonis leapt on elements of the new report to claim it was proof wind power was not directly to blame, and fault instead lay with computer software.
A spokesman for AGL Energy, which operates the wind farms, says it is doing its own investigations to examine “whether or not changes should be made” to their settings.
“This is a technical and fact- intensive exercise that takes time,” the spokesmans said.
“So any speculation as to the cause of the blackout is premature.”
In a speech at the SA Energy Forum yesterday, AEMO corporate development executive general manager David Swift said they assessed the bad weather forecast as “not requiring action”.
“In hindsight one doesn’t know whether that was maybe the best answer.
“We have a very organised process, a very scientific process particularly around lightening and bushfires, for when we do decide that the risks on the network are high and so we actually reclassify the probability of losing lines and that ... makes the market operate more conservatively,” he said.
“Certainly wind speeds of 100-120km/h could cause distribution outages but you wouldn’t expect that sort of speed would be sufficient to actually cause transmission problems.”
Mr Koutsantonis said questions remained about whether AEMO could have reduced flow across the interconnector ahead of the storm to make it more resilient and stimulate the generation of more gas power within SA that could have enhanced system stability.
Mr Koutsantonis said those matters were being investigated by state officials.
“We knew this storm was coming. Could there have been better preparation? I think so. What could that preparation have been? I’m not prepared just yet to say what that is, but I suspect having some measures in place may have made a difference,” he said.
AEMO found the most well-known characteristic of wind power, intermittency or variation of output depending upon wind strength, was “not a material factor” in the blackout. Wind turbines are designed so that when low voltage is detected at their terminals, normal control is suspended and a sequence of actions performed, described as ride-through control.
The purpose is for the wind turbine to remain connected to the grid so voltage can be recovered at the connection point.
“It is now known that five system faults occurred within a period of 88 seconds on 28 September 2016, leading to six voltage disturbances,” the AEMO report says.
“Preliminary discussions with wind farm operators suggest this inability to ride through all disturbances was due to ‘voltage ride-through’ settings set to disconnect or reduce turbine output when between three to six disturbances are detected within a defined time period.”
The Australian Energy Market Operator’s preliminary report, issued on October 5, found there were “multiple faults in a short period” when severe weather on September 28 struck high-voltage power lines near Port Augusta and in the Mid North.
Federal Environment and Energy Minister Josh Frydenberg said SA’s blackout “was a wake-up call that underlined the importance of energy security to all Australians”.
“Importantly it was the settings within the majority of the wind farms which meant they could not ride through the voltage disturbance caused by the storm,” he said.
Australian Energy Council chief executive Matthew Warren said the latest AEMO report “reinforced the need to modify the way we manage electricity grids”.
South Australia has the highest rate of renewable energy in the country, with a fraction over 40 per cent of the state’s power supply generated by renewables such as wind farms and solar.