Sungrow says advanced inverter trials show they can provide heart-beat of the grid in absence of coal

Chinese power technology giant Sungrow says it has completed what it says is “the world’s first large-scale grid-forming full-scenario validation,” putting battery and inverter technology through a series of extreme grid scenarios designed to mimic real-world disturbances.

The tests were conducted on a 30 megawatt (MW) grid simulation platform in China, and covered 14 scenarios over 138 hours and met different country standards, including those in Australia, which is likely to be among the first to deploy such technology at scale.

Sungrow says the tests – separately verified by TÜV Rheinland – responded well to short-circuit faults, frequency instability (inertial response) and complete blackout conditions; instances that are traditionally handled by large spinning machines powered by coal, gas or hydro turbines.

The findings are potentially significant, and follow similar conclusions by the likes of US-battery and systems developers Tesla and Fluence.

These companies argue that grid-forming inverters – usually with grid scale batteries and first widely deployed in Australia – can provide the essential “system service” for the grid that were traditionally provided by coal and gas generators.

But as fossil fuel technologies are phased out from the grid, the market operator and transmission companies have suggested that synchronous condensers – large spinning machines that do not burn fuel – are still needed to provide some of those services. And they are planning on spending billions doing installing them.

AEMO, however, is looking to trial grid-forming inverters in a specially created “isolated grid” in Australia to test the technology at a scale of 100 MW or more. The findings will be important, because inverter companies say that the services can be delivered at a fraction of the cost of syncons.

Mining giant Fortescue has reported that its grid forming inverters – while supporting around 80 MW of load – have successfully responded to potentially catastrophic events in the absence of fossil fuel generation, and that is the experience of many smaller, isolated grids.

Sungrow’s announcement is notable as the company has shown the detailed results of this capability under a range of extreme conditions rather than relying on data from simulations or smaller-scale grid testing scenarios.

Among these results, highlighted by Sungrow at their recent Global Renewable Energy Summit (GRES) in Hefei, were a 10 millisecond response time during a short-circuit test, where it provided reliable fault support.

“A short-circuit test was conducted using real arc-fault equipment to simulate the most severe fault conditions,” it says.

“Under identical fault scenarios, the grid-forming system remained connected and continuously supplied fault current, while conventional systems are more likely to disconnect.”

Other tests noted the ability to maintain stable frequency during disturbances, and a “black start” demonstration where the system restored voltage within 19 seconds before restarting the entire facility and infrastructure without external support.

The company also says the test scenarios included “on/off-grid switching, load switching, and oscillation dampening.”

These tests reflect a broader shift that’s underway in energy systems worldwide; from grids stabilising mechanically by spinning machines to grids increasingly being managing electronically by inverter based resources.

“As demand for grid-forming technologies continues to grow, validating their real-world performance is becoming increasingly important,” says Henry Liu, the general manager of the microgrid and grid solutions center at Sungrow.

“These results demonstrate grid-forming capabilities and mark a critical step toward the large-scale deployment of grid-forming technologies.” 

Note: The author travelled to China to attend the Global Renewable Energy Summit as a guest of Sungrow.

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