South Australia has one of the world’s highest shares of wind and solar. As synchronous generators retired or ran less during windy, sunny periods, inertia and system strength reduced with them. AEMO needed new sources of stability. Hornsdale, an existing 150 MW battery, was an obvious place to test whether an inverter could do the stabilising job of a spinning machine.

Hornsdale was already operating when its inverters were upgraded from grid-following to grid-forming, without new hardware. It now runs below about half its rated power most of the time, to keep headroom for the stability services it is contracted to provide. The battery can:

• Set the grid’s voltage and frequency, does not need a grid reference to operate
• Provide response imitating inertia of a synchronous machine
• Deliver FFR
• Improve system strength

The lower Yorke Peninsula is supplied by a single transmission line, so an outage on that line cuts supply to the whole region. There is also local wind and solar, including the 90 MW Wattle Point wind farm. The usual fix would be to reinforce the network or to add a synchronous machine. Instead, a battery was installed to hold this part of the grid up on its own when the line goes down.

When the transmission line goes down, the battery keeps the peninsula running on its own, with no synchronous generation. It is deliberately short duration, sized for network support rather than energy trading, so it has a lot of power relative to its storage. It can:

• Set the grid’s voltage and frequency, does not need a grid reference to keep running
• Provide response imitating inertia of a synchronous machine
• Improve system strength
• Provide FCAS
• Support restoration after a blackout on the peninsula

The eastern part of Michigan’s Upper Peninsula is fed through undersea cables across the Straits of Mackinac. As wind generation grew further west, power pushed east and overloaded those cables. ATC often had to split its system in two to cope. This converter station was built to control that flow. On the Upper Peninsula side, it runs grid-forming controls, with the stronger Lower Peninsula grid behind it acting as a buffer.

The station converts the power to direct current and back again, which breaks the synchronous connection between the two sides and lets the operator dictate the flow. It can:

• Control exactly how much power flows, and which way
• Control voltage independently of that power flow
• Deliver dynamic voltage support
• Damp power oscillations
• Operate stably when the Upper Peninsula’s grid is weak
• Form and sustain an electrical island on the Upper Peninsula
• Support restoration after a blackout on the Upper Peninsula

Scotland has some of the highest concentrations of wind generation in Europe. Wind connects through converters, which normally follow the grid rather than hold it up. The coal plants that did hold it up have closed. Now NESO buys stability through competitive tenders. Blackhillock was built to sell those services rather than energy.

Blackhillock won a long-term contract to supply stability, the first time a battery had been paid for this in Great Britain. It can:

• Set the grid’s voltage and frequency and does not need a grid reference to operate
• Provide response imitating inertia of a synchronous machine
• Improve system strength
• Deliver dynamic voltage support
• In addition to stability supply, it can engage in energy arbitrage and balancing services

FCR in Germany has always come from thermal and hydro generators. As those retire, the country needs faster and more accurate ways to hold frequency steady. The town of Bordesholm built a battery to earn revenue in that market. It also does something no German battery had done before, keeping the town supplied on its own when the main grid is not available.

Bordesholm battery participates in the frequency market, and can supply the town on its own if the main grid goes down. It can:

• Set the grid’s voltage and frequency, does not need a grid reference to operate
• Provide response imitating inertia of a synchronous machine
• Provide FCR
• Keep the town supplied on its own when the main grid is unavailable
• Support black start

When the San Juan coal-fired power station closed, PNM lost a major source of voltage support and fault current, while solar and wind kept growing across New Mexico. The developer needed the new solar and battery plant to run stably in a system with declining spinning generation. Late in the design, they decided to make the battery grid-forming.

Shallow Basket pairs solar with a battery, and the battery is the part that forms the grid, holding the whole plant steady. It can:

• Set the grid’s voltage and frequency, does not need a grid reference to operate
• Deliver dynamic voltage support
• Improve system strength
• Keep both the solar and the battery connected through grid faults

South Fork was the first utility-scale offshore wind farm in the United States, bringing 132 MW ashore on Long Island, which has weak connections to the rest of the grid. Long offshore cables meeting a grid like that can cause harmonic instability and voltage spikes at switch-on. The wind farm’s inverters follow the grid rather than setting it, so a separate device was installed to hold the voltage steady.

A STATCOM is a stability device on its own, with no generation or storage behind it, so it can support voltage but not frequency. This STATCOM runs grid-forming controls, while the wind farm’s own inverters do not. It can:

• Set the grid’s voltage, rather than following it
• Inject or absorb reactive power within milliseconds
• Improve system strength
• Operate stably where the grid is weak
• Help the grid recover after a fault

Oahu is an island grid with no neighbours to lean on, so when a generator trips, there is nothing to import to replace it. Closing the island’s 180 MW coal plant took away not just power it was producing but the stability that came with it. Hawaiian Electric went looking for a replacement that could do both jobs, and chose a battery built in two parts, one to hold the grid up and one to react fast when frequency moves.

The plant totals 185 MW and 565 MWh, split in two parts. A 135 MW grid-forming section sets voltage and frequency, and a separate 50 MW section delivers FFR in grid-following mode. Together they can:

• Set the grid’s voltage and frequency, does not need a grid reference to operate
• Imitate the inertia of a synchronous machine, from the 135 MW grid-forming section
• Deliver FFR from the separate 50 MW section, with full response within 250 milliseconds
• Provide transmission voltage support, shift solar PV output to peak demand and support black start

Finland is adding wind quickly while its conventional generation declines. Fingrid moved early to prepare for this. From 2023 it required grid-forming for new batteries in weak parts of the grid, and from 2025 has required all new grid-scale batteries to be grid-forming. Other system operators are moving the same way, with grid-forming requirements now being written into European network rules. The Alpiq battery was one of the first built under this rule.

Because grid-forming is a requirement in Finland rather than an option, Alpiq had to demonstrate the full set of capabilities before it could connect. It can:

• Set the grid’s voltage and frequency, does not need a grid reference to operate
• Provide response imitating inertia of a synchronous machine
• Improve system strength
• Improve voltage stability

Southwest New South Wales has one of Australia’s highest concentrations of solar and wind, and system strength has fallen as a result. In the early 2020s, developers were wary of grid-forming. It was seen as riskier, harder to get approved, and likely to interfere with trading. Darlington Point was designed to test whether a battery could provide system strength and still operate normally in the market.

Darlington Point was one of the first Australian batteries to connect with grid-forming controls under AEMO’s new framework, at a point in the network where system strength was short. It can:

• Set grid’s voltage and frequency, no need for grid reference to operate
• Provide response imitating inertia of a synchronous machine
• Improve system strength and voltage stability, provide FCAS and participate in energy arbitrage

Germany’s coal and nuclear phase-out is removing the spinning machines that supplied stability services such as inertia, voltage support, and fault current. Mehrum sits where two major north-south transmission corridors meet, carrying growing volumes of wind and solar south. TenneT needed a device that could replace stability services, and do it for frequency as well as voltage.

An E-STATCOM is a STATCOM with supercapacitors added. Energy stored in supercapacitors lets it inject short bursts of real power, so unlike a conventional STATCOM it can work on frequency not just voltage. It can:

• Set the grid’s voltage and frequency, does not need a grid reference to operate
• Provide response imitating inertia of a synchronous machine
• Deliver ±200 MW of real power within milliseconds
• Provide ±300 MVAr of reactive power to hold voltage steady
• Improve system strength
• Damp oscillations

Scotland generates far more wind power than it uses, and the surplus flows south to England over a corridor that is often constrained. Kilmarnock sits on that corridor. NESO contracted this battery through Phase 2 of its Stability Pathfinder programme, explicitly buying stability as a service. At 300 MW it is the largest contracted in that phase.

At 300 MW, Kilmarnock is the largest battery contracted in Phase 2 of the Stability Pathfinder, and it sits on the corridor that carries Scottish wind south. It can:

• Set the grid’s voltage and frequency, does not need a grid reference to operate
• Provide response imitating inertia of a synchronous machine
• Improve system strength
• Deliver dynamic voltage support
• Participate in energy arbitrage and balancing services

Broken Hill sits at the far western edge of the Australian National Electricity Market, about 700 km from the nearest major generation, on one of the country’s weakest transmission systems. When large solar and wind farms connected nearby, the region developed system strength problems and unstable power swings, and generation had to be cut back. The battery was put here precisely because the grid is so weak.

Broken Hill sits far from any large spinning machine, so the battery has to hold the local grid up largely on its own. It can:

• Set grid’s voltage and frequency, no need for grid reference to operate
• Provide response imitating inertia of a synchronous machine
• Improve system strength, damp power oscillations and provide energy services and FCAS

New South Wales knew it would lose inertia when the Liddell and Vales Point coal-fired power stations closed, and Transgrid, which owns the transmission network, had to find something to replace it. Wallgrove was the answer, and unusually it is owned by the network company itself, built to test whether a battery could supply inertia as a network service and still trade in the market.

Just under 5% of its storage is reserved for inertia and fast frequency response, so most of it remains available for trading. It can: 

• Set grid’s voltage and frequency, no need for grid reference to operate
• Provide response imitating inertia of a synchronous machine, deliver FFR, improve system strength and provide FCAS
• Participate in energy arbitrage

The 2 GW Liddell coal-fired power station closed in 2023, taking with it one of the largest sources of inertia and system strength in New South Wales. The Wallgrove battery had already been built to cover part of that gap. Now a 500 MW grid-forming battery is being built on Liddell’s own site, as part of AGL’s redevelopment of it into an energy hub, to replace the services the coal plant used to provide.

Liddell is being built on the site of the coal plant it replaces, and at 500 MW it is meant to show that grid-forming works at the scale of the machines it stands in for. It will:

• Set the grid’s voltage and frequency, does not need a grid reference to operate
• Provide response imitating inertia of a synchronous machine
• Deliver FFR
• Improve system strength
• Provide FCAS
• Participate in energy arbitrage

The Victorian Big Battery was not built for stability. It was built in 2021 to increase the amount of power that can flow between Victoria and New South Wales, and is contracted to do this in the summer. While most grid-forming battery projects are built that way from the start, this battery was retrofitted to be grid-forming.

The batteries and inverters stay in place. Grid-forming is added through control software, new protection equipment and metering, and the studies to prove it is safe. Once enabled, it will:

• Set grid’s voltage and frequency, no need for grid reference to operate
• Provide response imitating inertia of a synchronous machine, deliver FFR, improve system strength and provide FCAS
• Participate in energy arbitrage

Victoria is preparing to retire its large coal-fired power stations along with the stability services they provide, including Yallourn and Loy Yang. The battery sits at a 500 kV substation where the links to New South Wales and South Australia meet, so what happens there affects three states. It was built to hold that point steady as well as to store energy.

At 600 MW this is the largest grid-forming battery operating in Australia, and it sits at one of the most heavily used points on the national grid. It can:

• Set the grid’s voltage and frequency, does not need a grid reference to operate
• Provide response imitating inertia of a synchronous machine
• Deliver FFR
• Improve system strength
• Provide FCAS
• Participate in energy arbitrage

Almost all grid-forming batteries connect to the high-voltage transmission grid with only a few on distribution networks. That matters in Germany, where a growing share of generation connects at distribution level and the machines that used to hold the system steady are closing. Föhren was built to earn money on the energy market and to test whether a battery can hold up a distribution grid and restart it.

Föhren is connected straight into a substation on the distribution network, which is what lets it restart a section of that network on its own. It can:

• Set the grid’s voltage and frequency, does not need a grid reference to operate
• Provide response imitating inertia of a synchronous machine
• Support frequency regulation
• Improve voltage stability
• Support black start of a local section of the network

Suizhou has about 2,950 MW of wind and solar but only around 850 MW of local demand, and increasingly less room to export the surplus. The Baolin solar station, built in 2016, is part of a project to run the county of Guangshui on renewables alone, serving more than 200,000 people. To do that, its inverters were retrofitted to hold up the grid themselves, with no battery added.

About 60% of the station’s 50 MW of inverters, 27 in all, were converted to grid-forming control. Because there is no battery, the plant holds back a little of its solar output so it has something in reserve. It can:

• Set grid’s voltage and frequency, no need for grid reference to operate
• Provide response imitating inertia of a synchronous machine, switch seamlessly between grid-following and grid-forming operation, supply reactive power, form an electrical island and support black start

Gêrzê sits at 4,600 metres in western Tibet, on a grid that is both remote and weak. The solar plant was built at 30 MW but allowed to export only 1.5 MW, so most of its output was wasted. The battery is not there to shift energy in time. It is there to make the grid strong enough to accept the solar already built. Running it in grid-forming mode raised the export limit to 12 MW.

Only the battery runs in grid-forming mode. The solar PV keeps its standard inverters and gains from the stability the battery provides. The storage is split into many small units that work together. It can:

• Set the grid's voltage and frequency, does not need a grid reference to operate
• Provide response imitating inertia of a synchronous machine
• Inject fast reactive power to hold voltage steady
• Damp oscillations across a wide frequency range
• Improve system strength so the grid accepts more solar

Golmud sits in a remote part of Qinghai, with an enormous concentration of wind and solar on a weak transmission network. The site combines wind, solar, solar thermal and a battery in one coordinated plant, rarely built on one site. The battery was made grid-forming to set the voltage and frequency the rest of the plant follows, and the site was chosen deliberately, because the network there is weak.

The battery is the grid-forming part of a plant that also has wind, solar and solar thermal behind it, so it has to hold steady a mix of very different generators. It can:

• Set the grid’s voltage and frequency, does not need a grid reference to operate
• Provide response imitating inertia of a synchronous machine
• Support frequency regulation
• Provide fast reactive power support
• Improve system strength
• Give wind and solar a stable local reference

As coal plants retire, Great Britain is losing the spinning machines that supplied inertia, fault current and voltage control. Gas peaking plants only run when the demand is high, so most of the year they contribute nothing to stability. Immingham B was built so that its generator can keep spinning with the grid even when the turbine is shut down and burning no fuel.

A synchronous self-shifting (SSS) clutch between the turbine and the generator disengages on its own when the turbine slows down. The generator keeps spinning with the grid, and the plant switches from producing power to supporting it. It can then:

• Provide physical inertia
• Supply fault current
• Improve system strength
• Supply reactive power to regulate voltage
• Support black start
• Return to generating power quickly when needed

Ireland has one of the highest wind shares in the world, and aims to run at times with 95% of demand met by inverter-based sources (SNSP). As conventional plants retire, it needs new sources of inertia, fault current and voltage support. At Moneypoint, ahead of the closure of its coal units, a synchronous condenser was installed with a flywheel to store extra rotational energy.

The machine spins without generating any electricity, and a large flywheel on the same shaft stores extra rotational energy, giving Ireland more inertia from one unit than a synchronous condenser can provide on its own. It can:

• Provide physical inertia, boosted by the flywheel
• Supply fault current
• mprove system strength
• Supply reactive power to regulate voltage

The Western Cape draws most of its power over long lines from coal plants at the other end of the country, with little local generation beyond the Koeberg nuclear power station. Blackouts in 2005 and 2006 showed how exposed that left the region. Eskom needed peaking capacity quickly for the winter of 2007, and it also needed local voltage support at times when the turbines were not running.

Ankerlig has nine turbines totalling 1,338 MW, and four of them, 592 MW in all, have a clutch between turbine and generator. The synchronous self-shifting (SSS) clutch disconnects on its own when the turbine slows, leaving the generator spinning with the grid. Those four units can:

• Supply reactive power to regulate voltage
• Provide physical inertia and fault current
• Improve system strength
• Deliver these services without burning fuel
• Return to generating power quickly when needed

Southern Italy is losing the synchronous machines that used to hold voltage steady, as thermal plants close and wind and solar grow. The Brindisi Nord coal plant stopped generating in 2012 for economic reasons and sat idle. After winning a Terna tender for voltage regulation, A2A converted the generators of two of its units into synchronous condensers, and put them back into service in 2020.

Nothing new was built here. The coal plant’s own generators were left in place, disconnected from their turbines and reconnected to the grid, where they now spin without producing electricity. They can:

• Supply reactive power to regulate voltage

• Contribute fault current and inertia

• Run with no fuel and no emissions

Hydropower has always been a source of stability, because its machines spin in step with the grid. Newer variable-speed units are different. They connect through power electronics, which gives them more flexibility but means they usually follow the grid rather than help hold it up. At Z’Mutt pumping station, one unit was rebuilt to form the grid instead.

All of the machine’s power flows through its converter, so the converter is what connects it to the grid. Controlling that converter differently is what makes the unit grid-forming. It can:

• Set the grid’s voltage and frequency, does not need a grid reference to operate
• Inject or absorb power quickly
• Switch quickly between pumping and generating
• Run across the machine’s full speed range

Portugal has one of the highest wind shares in Europe, and needs plants that can balance it. Frades 2 can vary its power while pumping, not only while generating, unlike a conventional plant. It follows the grid rather than forming it, but it shows how much a modern pumped hydro plant can do within that limit.

The plant is 780 MW across two units. In pumping mode each unit can adjust its power by about ±45 MW, and by running pump and turbine together the plant can reach around 231 MW of frequency reserve. Each unit can deliver up to 110 MW within 1.3 seconds. It can:

• Adjust power while pumping, not only while generating
• Deliver fast active power and frequency response
• Inject reactive current within milliseconds during grid faults
• Optimise service provision through digital controls developed by EPFL

Wind turbines connect to the grid through converters, which normally follow the grid rather than help form it. Restarting a grid after a blackout has been a job for large synchronous plants. At Dersalloch, ScottishPower Renewables and Siemens Gamesa changed the control software across the whole wind farm, first to hold up an electrical island on its own, then to re-energise a section of network from a standing start.

Nothing was changed on the turbines themselves. Virtual synchronous machine (VSM) control was added in software across all of the farm’s turbines. They can:

• Set the grid’s voltage and frequency, does not need a grid reference to operate
• Provide an inertial response through VSM control
• Form a stable electrical island
• Re-energise part of the grid after a shutdown

Data centres are usually discussed as a problem for Ireland’s grid, because they consume so much and are growing so fast. But every data centre already holds batteries for backup power, sitting idle most of the time. At its Dublin campus, Microsoft changed the controls on that backup system so the batteries would also respond when grid frequency moves, without losing their backup role.

The batteries were already there, installed to keep the servers running if the grid fails. The change was in the controls, which now let power flow out to the grid as well as in. They can:

• Deliver FFR within milliseconds
• Keep full backup protection for the site
• Take part in EirGrid’s market through Enel X’s virtual power plant

DongSu sits in Inner Mongolia, where wind and solar have grown faster than local demand and there is limited capacity to export the surplus. The grid there needs both storage and stability. The station is made up of about 800 battery units across 28 hectares and was connected to the grid in August 2026 at the first attempt.

t 1,000 MW and 4,000 MWh, DongSu is large enough to hold up the local grid on its own while shifting surplus wind and solar. It can:

• Set the grid’s voltage and frequency, does not need a grid reference to operate
• Provide response imitating inertia of a synchronous machine
• Improve system strength
• Reduce curtailment of wind and solar

The Outer Cape depended on a single 21 km distribution network supply path, which left Provincetown exposed to outages from storms and equipment failures. The conventional fix would have been to build a second distribution line. Eversource built a grid-forming battery instead, able to supply the local network on its own when the rest of the grid is unavailable.

The grid-forming battery can energise and operate the local distribution network as an islanded microgrid when the Outer Cape separates from the main grid. It can:

• Set voltage and frequency inside the island
• Supply local load during grid outages
• Provide local voltage support
• Reduce outage duration
• Support automated islanding and restoration
• Peak shave during grid-connected operation
• Resynchronise the microgrid to the grid