This article is more than 1 year old

This article is more than 1 year old

Australia’s energy regulator has launched court action against four windfarm operators, alleging they failed to meet performance requirements during 2016’s statewide South Australian blackout.

About 850,000 homes lost power on 28 September that year, when severe weather conditions led to significant damage to SA transmission lines, causing voltage disturbances. The event heightened a fractious national debate about energy policy.

The Australian Energy Regulator has said a loss of wind generation after the voltage disturbances contributed to the the blackout.

It alleges subsidiaries of the four companies – AGL Energy, Neoen SA, Pacific Hydro and Tilt Renewables – failed to ensure their windfarms complied with a generator performance standard requirement and had automatic protection systems to ensure continuity of supply.

Windfarm settings triggered South Australian blackout, final energy report finds Read more

The regulator’s chair, Paula Conboy, said the alleged failures meant the Australian Energy Market Operator was not fully informed when responding to the system-wide failure.

“The [regulator] has brought these proceedings to send a strong signal to all energy businesses about the importance of compliance with performance standards to promote system security and reliability,” she said.

In an investigation published in December, the regulator said it did not intend to take formal enforcement action over the incident as it believed it would be more effective to focus on “remedial recommendations for improved processes”. It noted the unprecedented circumstances of the blackout.

A fact sheet released by the regulator at the time said the investigation found some instances in which companies did not comply with obligations but they “did not contribute to the state going black” and all key obligations had been met.

In a note attached to its statement on Wednesday, the regulator said that report applied to events leading up to the blackout and the subsequent system restoration and market suspension only. It said the charges related to the blackout itself, which was not the focus of that investigation.

AGL said it did not accept the the regulator’s conclusions, that it had complied with national electricity rules and would “strongly contest” the charges. It said the weather event was a once in 50-year storm and AGL had worked with the SA government and regulators to identify what could be learned from it.

“We are committed to working with the regulator and stakeholders to ensure the integrity of the energy market and the ongoing stability of South Australia’s electricity system,” an AGL spokesperson said.

Tilt Renewables said it believed it had acted in good faith and in accordance with the national electricity rules. Pacific Hydro declined to comment.

A market operator report in 2017 found the blackout had been caused by extreme weather, including two tornadoes with wind speeds of between 190km/h and 260km/h. It said windfarms rode out the grid disturbances prompted by the loss of a transmission line, but a protection mechanism in the turbines had triggered a sustained reduction in power in the state. About 450MW capacity was lost within seven seconds.

The sudden reduction in wind power prompted a significant increase in imported power through the Heywood interconnector, which links SA with Victoria. The surge tripped the whole system, resulting in the blackout.

The energy minister, Angus Taylor, said it was important that the regulator enforce market rules. “Our job is to make sure that we do everything we can as a commonwealth government to keep the lights on, and we expect the states to do that as well,” he said.

Conboy said the regulator would seek declarations, penalties, compliance program orders and costs.