Nestled amid green rolling hills in western Victoria, 150 tonnes of metal has begun spinning to help secure the electricity grid.
Next to the Ararat terminal station and inside a large grey shed, a steel blue “pony motor” turns a massive rotor at 750 revolutions a minute.
Operators took the machine for its first spin on 10 November, with final testing to continue until the end of the year before it is brought fully into operation.
When it officially syncs to the grid, the Ararat synchronous condenser – or syncon – will be by far the largest of its kind in Australia. This peculiar device will whirl away, available to keep the power system secure and respond in the event of disturbances such as storms or unplanned outages.
The Ararat syncon is a heavy and complex piece of equipment, supplied by the Austrian company Andritz. The rotor is lifted off its 300t frame by pressurised air to minimise friction, as a cooling system ensures things run smoothly.
The technology dates back to the 1950s, but is gaining importance as part of the energy transition. Australia has been an early adopter.
A large syncon was installed at Ouyen in north-west Victoria in 2019, followed by four in South Australia (an investment of about $166m in SA). New South Wales is now fast-tracking an order for five more machines.
The capital cost of a synchronous condenser roughly the size of Ararat’s is $137m, according to a report from the Australian Energy Market Operator (Aemo). One study suggests that in a 100% renewable energy system, the equivalent of up to 40 machines could be required across the electricity grid.
‘Robust and established’
The electricity system is a complex beast. While most people understand the concept of reliability (having the right amount of power to meet demand), fewer are familiar with security – the technical requirements for maintaining the safe and stable flow of electricity.
In a traditional power system, many of these requirements are met by big spinning generators powered by coal, hydro and gas. But as the share of renewable energy increases and coal and gas power plants close, it can be provided through other means. Syncon machines are one solution.
They use a small amount of electricity to operate, but enable more renewable energy to enter the system, so reducing overall reliance on fossil fuels.
Glen Thomson is the chief executive of Australian Energy Operations, the project developer. He says the Ararat syncon will unlock an additional 600MW of renewable energy in the region, by replacing the stabilising qualities of synchronous generators without the associated emissions. It’s one of 12 projects being delivered as part of the Victorian government’s $480m investment in strengthening and modernising the state’s grid.
Australia’s electricity system is based on alternating current (AC), which requires frequency and voltage to be kept within set bounds. “A synchronous condenser is really there for Aemo to use as one of many tools to help stabilise the grid, to make sure voltage and frequency fluctuations are managed,” Thomson says.
Maintaining the flow of electricity at a set frequency is a key feature of all modern power systems, says Prof Michael Brear, a mechanical engineer and director of the Net Zero Australia project at the University of Melbourne. It’s what allows electricity to be transmitted over long distances.
Australia, along with most European and many Asian countries, keeps its grid humming at a frequency of 50Hz (which means the electrical current oscillates 50 times a second). The United States chose 60Hz. Japan, for historical reasons, ended up with two different systems – 50Hz in the east, and 60Hz in the west.
“It could be any number within a reasonable range,” Brear says. The important thing with frequency is to maintain it.
Spinning machines such as syncons strengthen the gridby providing inertia, a physical quality that resists and slows changes in frequency, working a bit like shock absorbers. They can also be used to control voltage.
Aemo expects system security in a power grid dominated by renewable energy to be achieved through a mix of synchronous condensers, batteries and advanced inverters at solar and windfarms.
Brear says there is a debate between engineers about the best methods.
“My expectation is that we probably do need a certain amount of spinning metal to maintain system frequency,” he says, and syncons are a “robust and established” option that don’t involve significant costs.
“It’s complicated, it’s hard, we must get it right, but it doesn’t mean that it’s expensive.”
• This story was updated on 23 November 2025. An earlier version incorrectly stated that Australia’s first syncon was installed at Ouyen in Victoria.
