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MELBOURNE, Dec 12 (Reuters) - South Australia needs to reduce the risk of being "islanded" from the national elecricity network, a report said on Monday, following freak storms in September that led to a state-wide blackout.
Severe winds escalated into tornadoes and destroyed parts of two South Australian transmission lines on Sept. 28, which then overloaded several windfarms and caused them to cut out, the preliminary report by the Australian Electricty Market Operator (AEMO) found. piled pressure on the main power line bringing electricity from interstate, tripping it offline and "islanding" the state's power system. A severe imbalance between supply and demand then cut off power, leading to the state-wide blackout.
The preliminary report focussed on how to physically manage networks in the event of a loss of power to avoid a catastropic black-out. Broader issues about the transition to renewable energy are being reviewed by the federal and state governments.
The report said tornadoes had not been forecast by Australia's weather agency, while AEMO had not been aware that a power surge could force the state's windfarms to successively cut out.
It made 15 recommendations, including more investigation into how the state could load shed in response to sudden, excessive flows on the interconnecter with neighbouring Victoria state.
"Because of the current difficulties in forming a stable island in South Australia, it would be preferable to avoid islanding if at all possible," the report said.
Other recommendations included taking fast action to reblance supply and demand in the event of "islanding", looking at the level of risk where there is a concentration of wind farms and a detailed review of restart processes.
State power supplier Electranet said in November it would cost up A$2.5 billion ($1.9 billion) to prevent another blackout. Mining companies, steel mills and metals refineries were among the hardest hit. need to ensure power supplies remain reliable was underlined again on Dec. 1 when Alcoa (NYSE:AA)'s Portland smelter lost power, knocking out one of two potlines and raising doubts about the future of the plant. final AEMO report is due in March.