The cases, brought by the Australian Energy Regulator, came before the Federal Court on Friday, with AGL Energy Ltd, Neoen SA, Pacific Hydro Ltd and Tilt Renewables all accused of breaching the National Electricity Rules.

They relate to the performance of wind farms during the severe weather event that swept SA in September 2016 and ultimately triggered the mass outage.

The court heard scientific evidence will play a role in establishing responsibility for the failure before any question of penalty can be examined.

The storms damaged more than 20 towers in SA's mid-north, bringing down major transmission lines and causing a knock-on effect across the state's energy grid.

About 850,000 customers lost power, with some in the north and on the Eyre Peninsula left without electricity for several days.

A report from AEMO released about a month later found nine of 13 wind farms online at the time of the blackout switched off when the transmission lines came down.

It found the inability of the wind farms to ride through those disturbances was the result of safety settings that forced them to disconnect or reduce output.

In its action, the AER alleges each of the wind farm operators failed to ensure their plant and associated facilities complied with their standard requirement to ride-through certain disturbances.

It also alleges the wind farm operators failed to provide automatic protection systems to ensure continuity of supply in contravention of the National Electricity Rules.

The AER is seeking declarations, penalties, compliance program orders and costs with the four companies involved expected to defend the action.

The regulator has also launched legal action against the owners of the Pelican Point Power Station after it failed to notify authorities it had spare generator capacity during blackouts in February 2017.

Both cases will return to court later this year.

Australian Associated Press