Power interconnector into South Australia from national grid via Heywood, Victoria, system upgrade in 2016
ElectraNet took on the upgrade of the link from Heywood, Victoria, power connector into South Australia in 2016.
Diagram courtesy ElectraNet
The Heywood interconnector was commissioned in 1988 with the primary aim to move cheaper coal-powered electricity from Victoria to South Australia. In later years, it was used to increasingly to transport wind-powered electricity from South Australia to Victoria.
The interconnector was the first 275 kV (kilovolts) AC overhead electricity transmission line link between the two state’s electricity grids, as part of the National Electricity Market. The Victorian end of the interconnector was the substation at Heywood and, in South Australia, the South East substation near Mount Gambier. The Heywood Interconnector project work extended from South East substation to Tailem Bend substation to the Para substation at Gould Creek on the northeast outskirts of Adelaide.
In 2016, the Heywood interconnector was upgraded to increase the maximum available power transfer between South Australia and Victoria. The nominal capacity of the interconnector became 650 MW (megawatts). The South Australian part of the upgrade, by the state main grid provider ElectraNet, involved
• installing series capacitors on the two Tailem Bend to South East 275 kV transmission lines at the new Black Ranges site at Willalooka (half way between the South East and Tailem Bend substations);
• a control scheme to prevent overload of South East transformers during high wind energy export;
• upgrading assets at substations to allow use of at least full winter transmission line ratings along the 275 kV interconnector and the underlying 132 kV transmission network in the South East region; and
• decommissioning two South East 132 kV lines that cause thermal limits on the interconnector.
The Heywood interconnector became the focus of the South Australian 2016 power blackout when multiple windfarms reduced power during a major thunderstorm, after a tornado caused multiple towers on transmission lines to collapse. The Heywood interconnector became overloaded, as the missing generation was automatically drawn from Victoria. The tripping of the interconnector led to an islanding of the south Australian power system, which fell into a rapid frequency decline.
South Australia was without supply through the Heywood interconnector twice in February and March 2020 but managed to maintain power. During the March outage, the Australian Energy Market Operator (AEMO) took control of several of South Australia’s large battery as the most effective contributors for managing supply security. Generation was cut back from wind generators and large-scale solar projects, with most generation supplied by rooftop solar and a rampup of gas generators.