Power systems are entering a new era shaped by rapid electrification, net-zero targets, and the rise of inverter-based resources. These changes bring extraordinary opportunities, but also new challenges for grid stability. In the past, large industrial facilities used synchronous motors that naturally contributed inertia to the grid. Today, many very large loads, often data centres, are dominated by power-electronic interfaces and typically provide no rotational inertia at all. As a result, operators face inertia and system-strength conditions that fluctuate more quickly and with far less predictability. While they try to avoid running systems near stability limits, the pressure to integrate more renewables and use the network more efficiently is pushing the industry towards operating closer to physical limits, provided they have real-time visibility and measurement to do so safely.
Across regions, these pressures are visible in operational costs and incident trends. Great Britain’s balancing costs reached more than £4 billion in 2022 and are forecast to rise to £8 billion by 2030. Events such as the April 2025 Iberian system collapse illustrate how quickly disturbances can spread.
Traditional stability management relied on models and heuristics developed for predictable synchronous generation. These tools remain central to planning and risk analysis. However, they are less effective in a system shaped by advanced electronic systems that adjust power flows almost instantly. Distributed resources change continuously, adding complexity. Operators need to understand the system’s true dynamic state at any moment. Without that insight, they often resort to increasing reserve procurement or curtailing renewable generation to maintain security.
Reactive Technologies addresses this challenge head-on. Our GridMetrix® platform actively measures system inertia in real time by introducing small, precisely designed energy pulses into the network (modulation) and capturing the grid’s frequency response with high-fidelity sensors. These measurements provide clarity during periods of low inertia and high renewable output, conditions where models carry the greatest uncertainty. For operators, this means running closer to true limits safely and keeping more renewable generation online without compromising reliability.
An integrated view of system stability
Over time, GridMetrix® has evolved into a comprehensive stability measurement system, offering visibility of three linked pillars of dynamic operability: inertia, system strength, and oscillations, in one integrated view. By viewing these parameters together, operators gain a complete picture of grid stability, enabling faster and more confident decisions.
Reactive’s grid-edge measurement devices measure the voltage waveform 48 000 times per second with full GPS time alignment. This precision gives operators confidence to act quickly. It also enables rapid rollout in areas of concern. While primarily designed for inertia measurement, the measurement devices also capture oscillations, offering operators a multi-purpose tool for dynamic stability monitoring. Analytical tools present these measurements in both live dashboards and post event analysis, giving operators the data needed for immediate response and longer-term planning.
Real-time grid measurement does not replace planning models. Instead, it helps calibrate them and enhances model accuracy by anchoring them in measured system behaviour. As inverter-based resources grow, controller settings and plant performance can deviate from assumed values. Measured data reveals where these deviations occur and helps engineers adjust planning studies, dynamic models, and security limits accordingly. For operators, this means fewer conservative margins and more renewable generation online; without compromising reliability.
The combination of active measurement and traditional monitoring tools, eg, PMU-based passive observation, produces a more robust understanding of stability than either approach alone.
Real, measurable global impact
From Great Britain to Japan, leading operators are adopting Reactive’s solutions to unlock renewable hosting capacity and cut carbon emissions.
The National Energy System Operator (NESO) in the UK was the first to deploy real-time inertia measurement at scale, enabling up to 30% more renewable hosting capacity, and supporting an estimated reduction of 18 million tons of carbon dioxide each year. The project is expected to deliver $92.5 million in operational savings over 5 years. It has also been able to lower the minimum inertia required at national level, which has a significant cost benefit.
In North America, real time measurement supported a NYSERDA Future Grid Challenge project aimed at meeting New York State’s Climate Act targets. A major East Coast utility is deploying the technology for system strength measurement, with early results expected in 2026.
In Japan, HEPCO (Hokkaido Electric Power Company) is using real time oscillation monitoring and inertia measurement to support the country’s transition to carbon neutrality by 2050.
In Taiwan, Taipower’s deployment reveals that 34% of system inertia is residual (ie, inherent or ‘embedded’ in the system) and was previously unaccounted for. This insight informs renewable integration planning and enables the world’s first use of a battery energy storage system as the modulator for active inertia measurement.
In Australia, AEMO, with validation from the University of Melbourne, documented operational and planning benefits from real time inertia measurement in a market with rising renewable penetration. The study revealed that on average there is approximately 38% more inertia in the system than AEMO was able to estimate.
These examples show a common pattern: operators use real time measurement to
validate models, refine stability limits, and reduce precautionary actions, cutting costs and accelerating renewable integration.
Why local dynamics matter for system stability
Stability is no longer just a transmission-level concern. Increasingly, risks originate at the distribution level, driven by data centres, electronic loads, and distributed energy resources. A disturbance at a single node, such as oscillations from inverter-based resources or sudden demand changes from large loads, can propagate through the network and amplify into wider instability. Local variations in inertia and system strength influence how the entire grid responds to frequency and voltage changes. When these parameters fluctuate unpredictably, operators risk misjudging stability margins.
As mentioned previously, Reactive Technologies’ GridMetrix® platform provides an integrated view of dynamic operability, measuring inertia, system strength, and oscillations across the grid. Looking ahead, this capability is expanding to include power quality indicators such as flicker and harmonics, ensuring operators can manage emerging challenges at every level of the network.
Real-time measurement at the local level provides the high-resolution data needed to detect emerging risks early, prevent cascading effects, and maintain security across the whole system. Addressing these issues early helps operators avoid expensive grid upgrades and maintain service quality.
From measurement to prediction: the next frontier
Looking ahead, the next frontier is prediction rather than reaction. Real-time measurement provides the foundation, but operators increasingly need to anticipate stability risks before they emerge. Combining high-definition grid measurement with forecasting and AI-driven analytics enables this shift. Machine learning models use historical and live data to predict inertia, system strength, and oscillatory risk under changing conditions such as weather, dispatch schedules, and grid topology.
High-resolution performance data is critical to this process. It ensures predictive models are anchored in accurate, granular observations, allowing operators to trust forecasts and act decisively. These insights enable earlier scheduling of the right services, validating their impact in real time, and reducing reliance on precautionary actions.
Planning and operations are converging. The same data that informs control-room decisions will increasingly guide outage planning and long-term reinforcement studies. By aligning predictive analytics with established planning processes, we can shorten the loop between observed risk, operational mitigation, and structural investment, unlocking more grid capacity while ensuring a stable and resilient system.
Delivering a stable, low carbon grid
Grid stability and power quality are twin pillars of a reliable, low-carbon system. Global grids are not in crisis; they are transitioning to new conditions shaped by renewable generation, emerging load types, and tighter security margins that require high resolution measurement strategies.
Operators require tools that reduce uncertainty and provide clear visibility of dynamic behaviour. Real time measurement of inertia, system strength, and oscillations offer that visibility. It transforms uncertainty into actionable information, enabling operators to run stable grids closer to limits without compromising security while providing critical insights to planning teams as they design the future grid. If we are to achieve our ambitious goals for the future, then real-time stability measurement is one of the foundational elements it will be built on.
