A key report highlights the problems with South Australia’s high level of renewable generation, finding that control settings on wind farm turbines led to last September’s statewide blackout in South Australia.
The fourth and final report by the Australian Energy Market Operator into the September 28 event found wind farm settings “responding to multiple disturbances … led to the Black System”.
This is despite South Australian Premier Jay Weatherill repeatedly insisting that renewables had not contributed to any blackouts in the state.
Although the report said “wind turbines successfully rode through grid disturbances”, the report found a “reduction in wind farm output caused a significant increase in imported power flowing through the Heywood Interconnector” and caused it to trip, leading to the statewide blackout on September 28.
“Had the generation deficit not occurred, AEMO’s modelling indicates SA would have remained connected to Victoria and the Black System would have been avoided,” the report found.
A previous, unrelated report by AEMO and transmission company ElectraNet published in October 2014 had warned of this scenario.
The report had warned that because of the state’s high level of wind and solar generation, “SA can separate (from the national electricity market) due to the credible loss of the Heywood Interconnector”.
Today’s report identified three factors that “must be addressed to increase the prospects of forming a stable SA island and avoiding a Black System”.
These are sufficient inertia to slow down the rate of change of frequency and enable automatic load shedding to stabilise the island system in the first few seconds, requiring increases in SA inertia; sufficient frequency control services to stabilise frequency of the SA island system over the longer term; and sufficient system strength to control over voltages, ensure correct operation of grid protection systems, and ensure correct operation of inverter-connected facilities such as wind farms.
Happened six times before
According to AEMO, such unexpected “separation” and loss of the Heywood Interconnector has happened six times in the past 17 years, but the system has never completely collapsed.
“The key differentiator … is that there was significantly lower inertia in SA in the most recent event, due to a lower number of online synchronous generators,” the report said.
Synchronous generators include coal, gas and hydro, but the state’s last coal-fired power station closed last year because of South Australia’s more than 40 per cent renewables mix.
Immediately before the statewide blackout, wind was producing 48 per cent of South Australia’s electricity, with most of the rest being imported from Victoria.
But federal Labor’s energy spokesman Mark Butler said the software setting problem that led to the blackout, and has since been fixed, was “a national regulatory failure” rather than a failure of renewables.
“This is an issue that applies to all types of generation. It has been an issue in coal and gas, and was a significant issue in wind generators in South Australia last September,” he said.
“The wind farms were the generators in place, but these software setting issues can arise in coal-fired, gas-fired and renewable energy generators.”
‘A wake-up call’
Federal Energy Minister Josh Frydenberg said the statewide blackout “was a wake-up call that underlines the importance of maintaining the supply of reliable electricity”.
“AEMO’s final report confirms that the sequence of events of the blackout remains unchanged, starting with a storm damaging the transmission network,” he said.
“The report makes clear that the statewide blackout would not have occurred if the wind farms had ridden through a number of voltage disturbances across the network.
“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.
“Notwithstanding, action has now been taken to address these wind farm settings. AMEO’s conclusions from its final report will be an important input into the Finkel Review.”
The report made seven new recommendations.
These include assessing options for improved forecasting of when wind speeds will exceed protection settings on wind turbines, which would lead to ‘over-speed cut-outs’; to modify operational procedures for SA island operation to take into account the fact that, under islanded conditions, system strength may fall to a level where some wind farms might not be able to ride through credible voltage disturbances. AEMO also will support ElectraNet to identify and address any specific risks to the operation of protection systems due to the low levels of system strength that may be experienced if SA is islanded.
Of the 19 recommendations outlined in AEMO’s report, three have already been implemented, which address more rigorous weather warning monitoring and improvements in System Restart Ancillary Service testing.
Work has started on a further eight recommendations, with the remaining items due to be completed by December.
AEMO’s chairman Anthony Marxsen will discuss the report’s final recommendations and observations at a Committee for Economic Development of Australia forum in Adelaide today, AEMO will lead a discussion into the future security, sustainability and stability of the National Energy Market in Australia, within the increasing role that renewables will play and the growing frequency of extreme weather events.
The discussion will be chaired by respected energy thought leader Tony Wood from the Grattan Institute and feature incoming AEMO chief executive Audrey Zibelman along with Steve Masters from ElectraNet and Rob Stobbe from SA Power Networks.
The report highlighted the “technical challenges” of a rapid uptake of renewable generation and the resulting need for a co-ordinated, national planning approach for “energy transformation”.
This afternoon, following a business forum in Adelaide hosted by the Committee for Economic Development of Australia, AEMO’s chairman Anthony Marxsen said previoulsy unknown and overly sensitive protection mechanisms on wind farms had caused the blackout and not the weather, as federal and state Labor claimed.
“Frankly, if we had known we were going to lose three transmission lines due to tornadoes, we still would have been relatively confident that the grid would ride through that, without impact,” Dr Marxsen said.
“It was the drop off of the (wind) generation due to that control system that was the issue. This isn’t a question of renewables versus other generation types. It is a question of us having access to accurate technical data on what is connected to the grid.
“And we face this challenge all the time and we will continue to face it even more so as more and more inverter connected (wind and solar) equipment joins the grid.”
During the September blackout fierce storms brought down three major transmission lines in South Australia’s north. In its initial findings in October, AEMO said nine of the state’s 13 wind farms switched off because they were unable to withstand voltage disturbances, a finding that has been consistently ignored by the Premier and his Energy Minister Tom Koutsantonis as they blamed only the weather for the blackout.
AEMO’s report today found a need for a co-ordinated, national planning approach for “energy transformation”.
AEMO was continuing its work to “support the transition to a power system of the future, including working with stakeholders … and collaborative engagement with the Australian Energy Market Commission and the Finkel review”.
Mr Weatherill has said he was concerned about AEMO essentially investigating itself in regard to the blackout.
But he said he would wait until the report was public to make a full assessment.
“We hope it’s an exercise that has been carried out with due care and we will consider it once it’s been released,” he said.
Premier Jay Weatherill has proposed new powers for the energy minister to call an electricity supply emergency to “put South Australia first and give our state control over our security.’’
Introducing legislation this morning as part of his $500 million “self sufficient” energy plan to “go it alone” on power, the Premier said the new powers would give the energy minister power to rapidly respond to prevent blackouts when severe shortfalls are likely to occur.
He said South Australians were let down by the national market operator on February 9 this year, when AEMO chose to force blackouts rather than fire up generators to meet a predicted short fall.
The result was 90,000 customers forced into blackout during heatwave temperatures.
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