A grid-scale battery in the Scottish Highlands got a chance to prove its mettle in March when, 11 days after it started up, a massive wood-burning generator in northern England shut down unexpectedly. Suddenly 1,877 megawatts of supply was missing, causing the 50-hertz frequency of the grid’s alternating current to crash below its 49.8-Hz operating limit in just 8 seconds.
But the new 200-MW battery station leapt into action within milliseconds, releasing extra power to help arrest the frequency collapse and keep the grid running.
Conventional fossil-fuel generators have historically helped thwart these kinds of problems. With the inertia of their spinning rotors, their kinetic energy provides a buffer against rapid swings in frequency and voltage. But the response in the Highlands was one of the world’s first examples of a grid-scale battery commissioned to do this kind of grid-stabilizing job.
Without moving parts, the lithium battery storage site—the largest in Europe and located Blackhillock, Scotland—simulates inertia using power electronics. And in an innovative twist, the battery site can also provide short-circuit current in response to a fault, just like conventional power generators.
Four more of these battery sites are under construction in Scotland.
How Do Grid-Forming Inverters Work?
The batteries can deliver these stabilizing services thanks to their advanced grid-forming inverters that convert direct current from lithium batteries into alternating current for the grid, and vice versa when the batteries are charging. Rather than ‘following’ the grid’s frequency and voltage the way nearly all other grid-scale inverters do, grid-forming inverters march to their own drum, and can sometimes act faster than conventional generators.
“These grid-forming inverters that we’re installing in Scotland—nobody is doing that,” says Julian Leslie, chief engineer and strategic energy planning director for the National Energy System Operator (NESO), based in Warwick, England. Andy Hoke, an expert in grid-forming technology and principal engineer at the U.S. National Renewable Energy Lab, says Scotland’s additions definitely push the envelope. “They’re super exciting projects,” says Hoke.
Can the UK Operate Without Gas Plants?
NESO is relying on grid-forming batteries to help achieve an ambitious goal that it set for 2025: to show that the United Kingdom can live without its dextrous, stability-boosting gas-fired plants. The U.K. shut down its last coal-fired power plant last year, and by the end of this year NESO plans to demonstrate that it can also operate without gas plants.
“By the end of the year we’ll have a couple of hours with zero carbon operation, which is going to be amazing,” says Leslie. It would be the world’s largest demonstration of fossil-free grid operation.
This is no ‘eco ego’ stunt. Increased stability from power electronics means more solar and wind generators can connect to the grid, and
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The post “Grid-scale Batteries in Scotland Stabilize Power” by Peter Fairley was published on 08/04/2025 by spectrum.ieee.org