Tilt faces court action over 2016 South Australia blackout

By Gavin Evans

Aug. 7 (BusinessDesk) - Tilt Renewables is among four wind farm operators being taken to court by Australian authorities for their part in a blackout of South Australia’s electricity network in September 2016.

The Australian Energy Regulator is taking AGL Energy, Neoen SA, Pacific Hydro and Tilt to the Federal Court alleging their eight wind farms weren’t able to ride-through certain system disturbances as required under their generator performance standards.

The AER also alleges that the firms failed to provide automatic protection systems to enable them to ride-through voltage disturbances in order to ensure continuity of supply, as required by national electricity market rules.

“The AER 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,” AER chair Paula Conboy said.

She said the alleged failings contributed to the state-wide blackout, which cut power supplies to about 850,000 users that day, and meant that the Australian Energy Market Operator was not fully informed when it was trying to respond to the emergency.

“Providing timely and accurate information to AEMO is critical in ensuring power system security and the effective operation of the wholesale energy markets,” Conboy said.

The proceedings relate to Melbourne-based Tilt’s Snowtown 2 wind farm.

“Snowtown 2 Wind Farm believes it acted in good faith and in accordance with the applicable National Electricity Rules, and the company will continue to engage with the AER in an endeavour to resolve this matter,” Tilt said in a statement to the NZX today.

Tilt shares rose 1.5 percent to $2.74.

The AER is seeking declarations, penalties, compliance programme orders and costs.

The South Australia blackout on Sept. 28, 2016 took place during wind storms that wrecked transmission towers in other parts of the state.

A final investigation in March 2017 found that two tornadoes with wind speeds of more than 190 kilometres an hour had triggered the blackout by damaging three large transmission lines north of Adelaide just after 4 pm. A series of faults in quick succession caused voltage across the state grid to dip six times within two minutes.

That caused a range of generators to trip-off, in-turn increasing demand on the interconnector from Victoria, which in turn overloaded, leaving the state grid insufficient power to keep operating. Most consumers had power restored by midnight. Some wouldn’t get power till Oct. 11

An AEMO investigation showed that 456 MW of wind capacity – including Snowtown 2 - disconnected from the grid in less than seven seconds after the turbines had ridden-through a pre-set number of voltage dips within two minutes.

AEMO said that protection feature – the limit on low-voltage ride-throughs - had never been disclosed to it in the modelling provided by generators. It had never dealt with the issue before in Australia and could find no similar events reported internationally.

The Snowtown 2 turbines were set to shut down if they incurred six under-voltage disturbances in 30 minutes.

In its proceedings against Tilt, the AER notes that AEMO had not been aware of the existence of that protection system, which also stopped Snowtown 2 meeting its obligation to maintain uninterrupted operation during a transmission fault lasting up to 250 milliseconds.

It noted that the fifth network fault in the sequence leading to the blackout had been cleared with 80 milliseconds. The sixth disturbance, which shut down 34 of the 37 Snowtown 2 turbines still operating at the time, was triggered by automatic circuit-breaking equipment, another type of fault the turbines were required to ride-through.

“By reason of the 34 Snowtown 2 generating units ceasing to supply active power after disturbance D6, a loss of approximately 100 MW generation output was experienced from the Snowtown 2 wind farm.

“That loss of active power, together with losses of output from a number of other generating systems after disturbances D4 through D6, was a contributing cause of the black system event and blackout.”

In its filing, the AER noted that in October 2016, Tilt had modified the protection system at Snowtown 2 so that the turbines would ride-through up to 20 under-voltage disturbances within two hours.

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