Reactive Technologies gets €19m to measure a changing electricity grid
A power station trips. Electricity supply drops in an instant, while homes, factories and offices keep drawing power. The grid’s frequency begins to fall. Other equipment must respond before the disturbance spreads.
Grid operators prepare for events like this every day. But as the sources supplying electricity change, they need a better answer to one question: how much inertia does the system have right now?
Much of a conventional electricity grid’s inertia comes from heavy machinery spinning inside power stations. Those rotating parts store energy. When supply and demand suddenly fall out of balance, that energy briefly slows the change in frequency, buying time for other equipment to respond.
Solar panels and most modern wind turbines connect through electronic converters, so they do not automatically contribute inertia in the same way. Batteries and specially controlled inverters can provide other forms of stability support. For operators, the challenge is knowing what support the grid already has, what it needs, and where.
Reactive Technologies, headquartered in London with a research centre in Oulu, Finland, specialises in measuring that changing grid. On 23 September, the European Investment Bank (EIB) announced €19 million in venture debt for the company. Up to €7 million will support research and development in Oulu; €12 million will support deployment of its technology in the European Union.
So what makes Reactive particularly interesting?
How Reactive Technologies measures grid inertia
Grid operators have long estimated inertia using information about which generators are running, supplemented by estimates for other contributions to the system. Britain’s National Energy System Operator (NESO) has also adopted software from GE Digital that analyses changes in frequency and power flows to assess what it calls effective inertia. That software can forecast conditions ahead of time.
Reactive uses a different method. Its equipment sends a controlled pulse of power through the grid, then measures the system’s response. NESO has compared the principle to sonar: introduce a known signal and learn from what comes back. Reactive’s sensors and software use that response to calculate inertia directly.
An early British demonstration showed why testing the grid could be useful. On one day of the project, Reactive’s measurement found significantly less inertia than the system operator had estimated. The measured level came close to 130 gigawatt-seconds, described in the project presentation as a critical limit at the time. The presentation does not say that the finding prompted a particular change in how the grid was run. It does show that an estimate and a direct reading can give operators materially different pictures of their margin for error.
GE Digital’s and Reactive’s approaches can work together. One observes changes already occurring on the grid and produces forecasts; the other introduces a signal to test its response. NESO has used both to develop a clearer view of inertia than generator-based estimates alone can provide.
Reactive launched its inertia measurement service with Britain’s system operator in 2021 under the name GridMetrix. The company now calls its wider measurement platform GridVerix. Alongside inertia, the platform addresses system strength and oscillations: other aspects of stability that become important as the equipment connected to a grid changes. Inertia concerns how quickly frequency may change after a disturbance; system strength concerns how firmly parts of the network can maintain their electrical behaviour as equipment connects or conditions shift.
Why the EIB is financing its expansion
The EIB’s case rests on a problem facing electricity systems across Europe. More wind and solar generation is connecting to networks built around a different mix of power plants. Meanwhile, large electricity users, including data centres, are adding demand. Operators must accommodate both while keeping the system secure.
Better measurements could make some decisions less reliant on conservative estimates. An operator with a clearer view of inertia can judge how much additional stability support it needs to withstand a fault. Information about conditions in different parts of the network can also help with connection and investment decisions. The EIB says Reactive’s technology could help integrate more renewable electricity, reduce the deliberate curtailment of wind and solar generation, and lower operating costs. Those are intended benefits, rather than savings established by the new financing.
The bank is funding a specific next stage: further development in Finland and deployment within the EU. Venture debt gives a growing company capital without requiring it to sell the same ownership stake it would in an equity round. Reactive has already worked on a major electricity system in Britain and participated in an inertia measurement demonstration in Australia with the Australian Energy Market Operator and the University of Melbourne. The EU rollout will test how the platform fits other networks and operating practices.
From a measurement to a decision
A measurement can reveal a problem; it cannot fix it on its own. If a grid needs more stability support, operators still have to obtain it from suitable equipment or services. Reactive’s value depends on whether its readings help them make those choices more accurately.
That step remains an active area of work. NESO completed a project on validating inertia measurements in 2024 and is now developing methods to incorporate real-time readings into operational practice. Even on a grid where Reactive’s technology has been deployed, producing a number and deciding how to act on it are distinct tasks.
Nor does better stability monitoring remove every limit on renewable power. A wind farm may still need a new transmission line. A congested network may still need reinforcement. Reactive’s platform addresses what operators can learn about the grid’s behaviour, not how much electricity every cable can carry.
As GridVerix reaches more European networks, the test will be whether operators can show that its measurements changed how they ran the system: allowing more clean power onto the grid, securing it at lower cost, or identifying a risk they would otherwise have missed. The early British result shows that a direct reading can reveal something an estimate missed. The wider rollout must establish how often that knowledge changes the decisions that follow.
Liked this article? You can support our independent journalism via our page on Buy Me a Coffee. It helps keep MoveTheNeedle.news focused on depth, not clicks.