Windfarm settings triggered South Australian blackout, final energy report finds

The state-wide blackout in South Australia which prompted a national political storm over energy policy was caused by extreme weather, which triggered a cascading sequence resulting in the state separating from the national energy market, according to a final assessment from the Australian Energy Market Operator.

The final report finds that the state’s windfarms rode out the grid disturbances prompted by the loss of key transmission lines during two tornadoes with wind speeds between 190 and 260 km/h – but the activation of a protection mechanism in the turbines triggered a sustained reduction in power in the state, with a drop of 456MW over a period of less than seven seconds.

The sudden reduction in wind power on the day of the blackout prompted a significant increase in imported power flowing through the Heywood interconnector, which then tripped the whole system and triggered the state-wide blackout on 28 September.

The market operator says “the intermittency of the wind was not a material factor in the black system event itself” but it says the impact of the sudden drop in power due to the in-built protection mechanisms was “greater than expected”.

Curiously, the Aemo says it was “unaware of this protection feature before the black system event”.

It says it has now asked for the control settings governing windfarms to be overhauled to remove the risk of such an event happening again. It says the changes will improve its ability to forecast the impact of over-speed protection during high wind conditions.

The energy market operator warns in its final assessment of the SA blackout that a significant change in the generation mix in the national electricity market means it is no longer appropriate to rely solely on coal and gas base-load power – synchronous generation – to provide voltage control, frequency control, inertia and system strength.

It says ensuring stability in the grid will require new responses, from looking at non-synchronous generators where that is technically feasible – meaning using wind power to stabilise the grid – or “non-network services, such as demand response and synchronous condensers”.

Demand response means encouraging consumers to lower their energy consumption during periods of peak demand.

The Aemo has another pointed message for governments in its final assessment of events in South Australia last September. It says the technical challenges associated with the current change in the electricity-generation mix are best managed by both regulatory and market means.

It says the transition “must be managed with the support of efficient and effective regulatory and market mechanisms, to ensure the most cost-effective measures are used in the long-term interest of consumers”.

The final report, which will trigger a fresh round of political infighting between SA and the Turnbull government, supersedes Aemo’s three previous preliminary reports on the blackout.

It comes amid lobbying associated with the Finkel review for the Turnbull government to consider adopting an emissions intensity trading scheme for the electricity sector.

A string of peak bodies have already urged the Coalition to adopt a market mechanism to drive the transition to lower emissions power sources in electricity, including the National Farmers Federation, the Investor Group on Climate Change and the Business Council of Australia, which explicitly called for an emissions intensity scheme.

A number of experts believe an intensity scheme would provide a market signal to allow an orderly transition to low emissions electricity sources, and allow the transition to occur at the least cost to households and businesses.

The current consensus around carbon pricing is a major turnaround in a short period of time. Three years ago some of the same groups urged the parliament to get out of the way so that Tony Abbott could repeal the Gillard government’s so-called “carbon tax”.

But the government thus far has rebuffed all entreaties on emissions trading.