Coal closure delays and soaring prices mean more batteries and fewer syncons to keep heartbeat of grid

Australia’s biggest transmission company is to seek more grid forming batteries to maintain the heartbeat of the country’s biggest state grid because of the increasing cost and delivery delays of competing and traditional technologies.

In a significant move, Transgrid, which operates the transmission lines in New South Wales, says has updated its plan to maintain system strength – the so-called heartbeat of the grid – as the state prepares for the exit of its four remaining coal fired generators.

The technology choices of what is needed to provide system strength have been mired in controversy and debate in recent years, with transmission companies – who are responsible for maintaining the heartbeat of the grid in their respective states – favouring traditional synchronous condensers.

These spinning machines don’t burn fuel but replicate the synchronous generation traditionally provided by coal and gas generators. But inverter suppliers, including US giants Tesla and Fluence, and Germany’s SMA, have argued that grid forming inverters can do the same job at a fraction of the price.

It now seems that while the transmission companies, and the Australian Energy Market Operator, are yet to be convinced of all the inverter company claims, they are being forced to modify their plans because syncons are proving to be more expensive to buy, and harder to get.

The issue was flagged in AEMO’s recent Integrated System Plan, which noted that many countries are competing for the same materials and technologies, which is exacerbating delivery risks and pushing up costs.

“Australia may not be able to access reliable and cost-effective supply of these assets as global demand remains high, especially if the global supply chain is vulnerable,” AEMO noted.

Now Transgrid has announced that it will cut the number of planned syncons in the first two phases of installations from 10 large units to 8, and allow an expanded role for grid forming batteries in later stages to keep the NSW grid strong and reliable as coal is phased out.

Part of the reason cited by Transgrid is that AEMO has flagged that coal plant closures may happen later than previously thought, giving more time for grid forming batteries to prove their worth.

“Transgrid has optimised its preferred system strength portfolio in response to rapidly changing market conditions, including the rising cost and delayed availability of synchronous condensers, and updates to anticipated NSW coal retirement timelines,” the company said in a statement on Tuesday.

“The power system is becoming more complex at a faster rate, with shifting demand patterns, evolving technologies and multiple possible future pathways,” Transgrid executive general manager of network Jason Krstanoski added in the same statement.

Krstanoski still insists that syncons will remain a critical foundation for system strength, and it considers five large units are essential to meet grid needs when the Eraring coal generator closes in April, 2029.

But the next phase may see changes, with the potential coal closure delays offering more time for grid forming batteries to prove that they can help meet the “minimum” level of system strength as well as the “efficient level” of system strength which they are already meeting.

“We’re creating a pathway for grid-forming batteries to form part of the minimum-level portfolio in a measured way, with their role subject to confirmation of their technical credibility, which we hope to see in the coming years,” Krstanoski said.

“This includes confirming that battery systems can reliably provide the required characteristics and performance of system strength needed for the safe operation of protection systems, before we rely upon them to deliver it in practice.

“Our portfolio includes fallback options such as hydro and gas support, ensuring minimum system strength levels can still be delivered if battery capability is delayed or under-delivers.

“By combining proven infrastructure with emerging technologies, we are maintaining system security while increasing flexibility and reducing costs for consumers.”

Tesla has argued strongly that grid forming inverters can provide all the system strength services required for the grid, including maintaining fault current.

This was supported by SMA Global CEO Jürgen Reinert , who said in a recent episode of the Energy Insiders podcast that it is possible to “fully drive the entire grid on photovoltaics, together with wind, and storage of course” with clever energy management and grid functionality.

“This is hard to believe for people that were used to the central form of power generation and having rotating masses in order to keep the inertia, but that is possible with power electronics,” he said.

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