Voltage collapse the cause of SA blackout

The Australian Energy Market Operator (AEMO) has updated its preliminary findings into the cause of the of the the South Australian power system failure during a recent severe weather event. 

AEMO says that five transmission line faults, all occurring within a period of 88 seconds, led to six voltage disturbances on the network and essentially meant that blackout was all but inevitable. 

Clean Energy Council Chief Executive Kane Thornton said that “no power grid in the world is designed to manage the rapid consecutive collapse of the three major transmission lines” as sustained in SA.

According to the AEMO report, “Data now shows that nine of the 13 wind farms online at the time of the event did not ride through the six voltage disturbances, resulting in a loss of 445 MW of generation. Preliminary discussions with wind farm operators suggest this inability to ride through all disturbances was due to ‘voltage ride-through’ settings set to disconnect or reduce turbine output when between three to six disturbances are detected within a defined time period.

“Thermal generators remained connected up until the SA system disconnected from the remainder of the National Electricity Market (NEM). The Heywood Interconnector remained connected up until the sudden increase in electricity flow resulting from the loss of generation caused the automatic protection mechanism to disconnect the lines.”

According to Thornton, “No evidence has been provided to show that the system would have remained up and running if wind farms in the state had not tripped off to protect themselves in an unsafe electrical environment.

“There is obviously a lot to learn from all facets of the event, from the operation of the interconnector to the robustness of the transmission network, the restart procedures, the planning prior to the extreme weather and the operation of power generators.

“The wind industry is committed to working with AEMO to look at current standards and operating procedures and whether these need to be refined,” he said.

Thornton said while the network operator was able to restart South Australia’s power relatively quickly given the serious damage to the transmission system, many processes and procedures did not go to plan.

“The review of power system security led by Chief Scientist Alan Finkel is a good opportunity for an independent look at every link in the chain and to work out how our power system can be strengthened in the future,” Thornton said.