Freshly reeling from a statewide blackout, South Australia’s government in March released an energy plan that seeks to cut its reliance on an electricity interconnector with eastern Australia that feeds the state coal power. The state, which recently shuttered its last coal plant, pointedly said the national electricity market is failing and stressed it wants to rely on wind, solar, and natural gas that it produces despite an elevated risk of power shortages and summer blackouts.
The state suffered a so-called “Black System” event that shut off the lights for 1.7 million South Australians on September 28, 2016. The cause of the event, in a state that gets a majority of its power from natural gas and wind, has been disputed, but it has set off a raging debate about the state of Australia’s electricity system and policies that will shape its future power mix.
In a final report following an investigation into the September 2016 event released on March 28, the Australian Energy Market Operator (AEMO) concluded that at about 4 p.m., two tornadoes damaged a single circuit 275-kV transmission line and a double circuit 275-kV transmission line, some 170 kilometers apart, causing them to trip.
A sequence of faults in quick succession resulted in six voltage dips on the South Australian grid over a two-minute period. As the number of faults grew, nine wind farms in the state activated protective features, reducing power by 456 MW over a period of less than seven seconds. That ultimately caused a significant increase in imported power through the main interconnector linking South Australia with neighboring Victoria to such a level that it tripped the line.
About 90% of power had been restored within eight hours following the event, but it continues to cast a shadow over the state’s power reliability. AEMO said in its report that changes made to the wind turbine control settings removed the risk of recurrence of the “same number of disturbances.” It also called for the prompt improvement of frequency regulation services to reduce the risk of islanding.
The federal government, led by Prime Minister Malcolm Turnbull of the Liberal/National Coalition, used the report’s findings to fan claims that the high penetration of intermittent renewables in the state was to blame for soaring energy prices and compromised grid reliability. Federal Energy Minister Josh Frydenberg said, for example, that the statewide blackout “was a wake-up call that underlines the importance of maintaining the supply of reliable electricity,” cautioning other states that 50% renewable energy targets would get them in trouble. He said: “The report makes clear that the statewide blackout would not have occurred if the wind farms had ridden through a number of voltage disturbances across the network.”
Others pointed out that AEMO had previously warned of similar scenarios owing to the state’s high level of wind and solar generation. AEMO noted in its report that a complete loss of the interconnector with Victoria had occurred at least six times before. Three of those events were initiated by disconnection of generation in South Australia.
“The key differentiator between the 28 September 2016 event and [the] other three events is that there was significantly lower inertia in [South Australia] in the most recent event, due to a lower number of on-line synchronous generators,” it said. AEMO noted, though, that it hasn’t carried out any studies to determine whether more baseload generation—including coal, gas, and hydropower—would have helped maintain the stable and secure operation of the interconnector.
South Australia’s last coal-fired power plant, the aging Northern power station in Port Augusta, was closed last year along with a nearby coal mine, rendered uneconomical by an oversupply of generation, which included a recent surge in renewables. Renewables make up more than 45% of its power mix today. As of early April, the state relied on 714 MW of gas generation capacity and 646 MW of wind energy (Figure 5) for the bulk of its power.
Despite criticism of its reliance on renewables, South Australian Premier Jay Weatherill on March 14 took what was widely considered an intervention in the national energy market and launched a comprehensive plan to secure the state’s power supplies. As he introduced the plan, Weatherhill said it was “clear the national energy market is failing the nation, as well as South Australia.”
The A$550 million plan, “South Australian Power for South Australians,” he said, will be paid for from state government surpluses. It entails building the largest grid-connected battery in Australia to store power; construction of a A$360 million state-owned 250-MW gas-fired power plant to provide emergency backup power; new ministerial powers to direct the market to operate in the interests of South Australians; incentives for increased gas production using gas produced in the state; and the creation of an energy security target.
Energy Minister Frydenberg, predictably, issued a sharp statement about the plan: “Going it alone created South Australia’s problems and going it alone won’t fix South Australia’s problems,” he said. “In fact, the measures announced today will only increase electricity prices for South Australians. It has the potential to increase prices for Victorians, for people in New South Wales, and in Tasmania.”
—Sonal Patel is a POWER associate editor