The Australian Energy Market Operator (AEMO), which last week ordered “load shedding” in South Australia blacking out 90,000 customers, says it can’t guarantee a repeat of the incident, which came about despite there being enough gas generation available to serve the state’s needs.

AEMO released a report yesterday which found load shedding was the only remaining viable option to avoid damage to the electricity network after demand soared higher than expected and power from wind farms fell more rapidly than forecast.

The report also revealed more details of AEMO’s negotiations over a gas-fired power unit at Pelican Point, which it determined could not be brought online in time to provide extra electricity.

However, the report also revealed a blunder by South Australia’s electricity distributor, SA Power Networks, which has apologised to 60,000 customers it wrongly blacked out.

AEMO asked SA Power Networks to cut demand by 100 megawatts; instead, an automated computer system shed three times as much.

SA Power Networks has apologised for the software error.

“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.

AEMO’s executive general manager for stakeholders and information, Joe Adamo, said today the incident illustrated the complexity of the energy system, which was built for a different era.

He said he “certainly” could not guarantee that the incident wouldn’t happen again, however he did not accept that AEMO “dropped the ball”.

“Yes, there are areas of the industry and our organisation’s one of them that needs to improve and needs to evolve in terms of managing forecasting and managing the complexities of intermittent generation and how we all work together to try to develop what is an evolution of a power system that was developed for a different century,” he told ABC Adelaide.

He said the task of forecasting and planning for demand had become complex.

“So what we’re facing now in South Australia and potentially in other parts of the network is the depth of the system is not there any more for us to cope with these sort of things…,” he said.

The Climate Council said the market operator had let South Australia down in how it handled the energy supply issues.

“AEMO did not adequately protect South Australia,” it said.

“Despite many days notice of the looming heatwave, AEMO did not ensure reserve supplies were operating in the event demand increased suddenly.”

South Australian Energy Minister Tom Koutsantonis said the load shedding happened because “AEMO can’t manage demand forecasts and SAPN have got dodgy software”.

“So I think quite frankly the entire national market had one of its worst days ever and I think it’s a lesson for all of us that whether it’s government or whether it’s the private operators or the national regulators or the national operators, everyone’s got to pull their finger out because this just isn’t good enough,” he told ABC Adelaide.

– with AAP