South Australian Blackout Renews Debate on Renewables' Role in Reliability

The entire state of South Australia suffered a blackout on the afternoon of September 28. The cause of the event has been disputed, but it has left Australians in a raging debate about the state of the country’s electricity system and policies that will shape its future power mix.

The so-called “Black System” event that shut off the lights for 1.7 million South Australians began at 4:18 p.m. during one of the worst storms to hit the state in 50 years. A preliminary report assessing the event from the Australian Energy Market Operator (AEMO)—which oversees reliability of the interconnected power systems in the country’s eastern and southeastern seaboard, as well as the wholesale electricity market and power system in Western Australia—suggests that the state had a supply of 1,895 MW to serve its 850,000 electricity customers immediately prior to the event. About 883 MW of this supply came from wind farms and 330 MW from natural gas–fired plants, but the state also received 613 MW from electricity imports via two interconnections with neighboring Victoria, along with generation embedded in the distribution network.

The storm, which brought gale-force winds and at least two tornados, knocked four transmission lines out of service and caused five system faults within a 90-second period. In response to six resulting voltage disturbances, the state sustained an unexpected loss of 445 MW from nine of the 13 wind farms that were online at the time and did not “ride through” the disturbances, AEMO said. That, in turn, prompted an increased flow on the main interconnector with Victoria (Heywood). Almost instantaneously, the increased flow and loss of generation tripped the interconnector, cutting off 900 MW of supply from Victoria, leaving a crucial generation deficit in South Australia—prompting system frequency to collapse rapidly, before critical load-shedding measures could be implemented.

Network service providers scrambled to restore service almost immediately after the blackout ensued, but according to AEMO, the Black System condition continued until 6:25 p.m. the following day—a total of 26 hours and seven minutes—when about 90% of load had been restored. South Australian spot markets, meanwhile, weren’t resumed until October 11. Only three of the four damaged transmission lines were restored by October 12, aided by the construction of temporary towers.

Immediately after the event, several politicians went on the record to blame South Australia’s reliance on renewables for the crippling lapse in reliability. In 2014, some noted, the state moved to increase its renewable energy production from 33% by 2020 (which it had achieved by 2014) to 50% by 2025.

On the morning of September 29, Deputy Prime Minister Barnaby Joyce told a Sydney radio station, “If you turn power into just a complete social policy and say well we are going to save the planet one state at a time and in so doing you create vulnerability to your state, so that if it comes under stress with a severe lightning storm, as they did, that this makes it more likely that you will have a total blackout.” Joyce’s criticism was echoed widely by industry observers. These groups have issued warnings about South Australia’s rising electricity prices, which they say stem partly from a renewables surge but also from the state’s reliance on the Heywood interconnector. One observer noted that South Australia saw a price spike and supply crisis just this July when that interconnector was closed for maintenance.

The renewable mandate is also typically cited for precipitating baseload coal plant closures. This May, South Australia’s last coal-fired power plant, the 520-MW Northern Power Station (Figure 1) owned by Alinta Energy in Port Augusta, retired. It joined the 240-MW Playford B, a plant that was first mothballed in 2012 and then permanently shuttered in October 2015. Alinta said that the plants, along with its Leigh Creek Coal Mine, couldn’t return to profitability “due to a significant oversupply of power generation in South Australia as a result of falling electricity demand and significant growth in renewable energy in the state.”

South Australia

1. Closed. On May 9, 2016, Alinta Energy closed Flinders Operations, which encompassed Augusta Power Station (shown here, including the Northern and Playford B Power Stations) and Leigh Creek Coal Mine in South Australia. Courtesy: Alinta Energy

For now, as AEMO continues to investigate the event, it says it will consult with wind farm operators and wind turbine manufacturers to better understand the impact on the power system of their “ride through settings.” Several wind farms have already implemented revised settings allowing them to ride through a higher number of disturbances, the entity said.

For the Australian Energy Council, an industry group that represents a majority of electric businesses that operate in wholesale and retail markets in the country, the focus should rest on how to best make the transition to a “new” electricity system. “South Australia is a living experiment in how we manage high levels of renewables in modern electricity grids. It is hard to anticipate and test for real world situations like this until they occur,” said the group’s chief executive Matthew Warren. “While the blackout was caused by a cascading set of events from extreme storms on the day, the most important thing is that we learn from this experience and do everything we can to prevent it reoccurring in the future.”

Sonal Patel, associate editor (@POWERmagazine, @sonalcpatel)

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