Within 10 minutes SA Power Networks network controllers raised concerns that more load was being shed than the 86MW the load-shedding system was indicating. This meant three times more households and businesses had their power cut than was necessary."We have put in place steps to prevent a recurrence, while continuing detailed technical investigations into why the load-shedding software did not operate correctly," the company said.

SA Power Networks – which was privatised in the late 1990s and is majority owned by Cheung Kong Infrastructure – delivers electricity through power lines to about 750,000 residential customers and 100,000 business customers in the state. It is the distribution network manager in SA and maintains the poles, wires and sub-stations. Another company, ElectraNet, runs the transmission lines that carry electricity for long distances across the state.

SA Energy Minister Tom Koutsantonis labelled the whole situation a litany of errors.

The AEMO report found wind power was half of what was expected on the afternoon of Wednesday, February 8 while thermal generators failed to answer a request to provide more supply into the system.

"Load shedding then became the only available option for AEMO to restore system security," AEMO said in its incident report released on Wednesday afternoon.

The SA blackout has reignited a national debate about whether SA's energy network has become too vulnerable because it sources 40 per cent of its power from intermittent renewable energy.

The AEMO report showed that at 4pm about 200 megawatts of wind was forecast up to 6.30pm on February 8, but by 6pm the actual wind generation was 100 megawatts and falling.

The report highlighted the increased urgency on the Wednesday afternoon when AEMO asked AGL Energy and French-owned Engie about bringing extra capacity into the market to deal with a looming shortfall.


At 3pm, it issued a statement about a forecast lack of reserve – or LOR 1. At 4.07pm Engie told AEMO its Port Lincoln generating units (73 megawatts) were not available due to a communications system problem.

At 5pm, AEMO upgraded its assessment of the looming power shortfall to a LOR2 telling generators "should a market response prove inadequate AEMO has the authority to direct any available generation on".

At 5.18pm, Origin Energy told the market operator that its Quarantine power station's unit 4 (20 megawatts) was not available. By 5.25pm AEMO concluded the power network was "not in a secure operating state" and gave itself 30 minutes to rectify the situation.

At 5.39pm, AEMO asked Engie about the availability of the second unit at Pelican Point gas-fired power station. The unit has not been in use since April 2015 and Engie says it doesn't have the gas to run it and it would take at least four hours to get it up and running. AEMO asks Engie to explore options and advise further.

At 5.42pm it got worse for AEMO when AGL advised them Torrens Island A1 (120 megawatts) would not be available until Monday due to a tube leak being repaired, while Torrens Island B1 was only operating at a reduced capacity of 50 megawatts due to high ambient temperatures.

At 5.49pm, Origin told AEMO its Quarantine 4 unit was available and it begin to crank it up. Engie says Pelican Point's second unit could be ready by 7pm.

But by 6pm – with the power system deemed to be "insecure" for 35 minutes – AEMO concluded "all supply-side options to return the power system to a secure operating state have been exhausted".

At 6.03pm, AEMO declared low reserve 3 (or LOR3) for SA and issued a directive to shed 100 megawatts of power from the network. In the end, more than 300 megawatts was shed, 200 megawatts more than required.


At 6.30pm, AEMO asked SA transmission company Electranet to restore 100 megawatts and full load was restored by 7.08pm.

Chief Scientist Alan Finkel – who is conducting a review on energy security for the Turnbull government – said SA's latest brownout has again illustrated the security of the power system "is not as robust as when it was first designed" but rejected the idea the situation has become a crisis.

Dr Finkel said there was "no single villain" for the supply problems, but several reasons contributing to the string of issues.

Federal Energy Minister Josh Frydenberg said the AEMO report confirmed the "complexity and fragility" of maintaining energy security in SA.

"In particular the difficulty of forecasting and managing high levels of intermittent generation," he said. "That is why the government is focused on energy storage and ensuring sufficient base load power in the system."