Image: National Grid ESO

A 5MW ultracapacitor is to be deployed on the GB grid by system operator National Grid ESO to measure the system inertia.

The ultracapacitor, set to be the world’s largest, is to be constructed by Spanish technology group Ingeteam under contract to energy technology provider Reactive Technologies.

The ultracapacitor will form part of Reactive’s GridMetrix inertia measurement service, which will provide a real-time view of the power system stability into National Grid ESO’s control room.

Once operational, the ultracapacitor will be used to directly measure inertia by sending pulses of power through the grid, which will be recorded and processed by Reactive’s measurement devices and cloud platform. The technology can be likened to ‘sonar’ for the power grid and provides a step change in accuracy and granularity from the current estimation models.

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Increasing levels of renewable and other non-synchronous generation are leading to a decline in the level of power system inertia and the need for new methods of establishing and managing the system stability. Moving towards a system that provides a real-time view of inertia gives greater visibility on the stability of the network, enabling the integration of greater amounts of renewable energy.

“The electricity grid in Great Britain is changing rapidly, with increasing levels of renewable, decentralised power,” comments Rob Rome, head of national control at National Grid ESO.

“This pioneering measurement tool is part of a range of new world-first approaches to grid management and will boost our visibility of inertia across the system, helping to bring more renewable generation online. It’s exciting to see another significant step forward towards being able to operate a zero-carbon electricity grid by 2025.”

The ultracapacitor will be located at Wilton International on Teesside, an energy intensive industrial business site that has the ambition to become Britain’s first zero-carbon industrial cluster. Delivery is expected in Spring of 2021 with operation due to commence in the Summer.

Effective inertia measurement

The ultracapacitor is one of two new tools under development for National Grid ESO to measure and manage the inertia.

The other is an effective inertia measurement and forecasting software from GE Digital, which measures effective inertia non-intrusively and on a regional basis using measurements of grid frequency and power flows on a 20ms timescale.

Effective Inertia captures not only the physical inertia from rotating synchronous generation but also the inertia-like effects of the non-synchronous generation and passive responses from domestic and industrial demand.

This should give operators a real-time view of the inertia in each region of the grid as well as the total GB level. By applying advanced machine learning, the software also provides forecasts of effective inertia based on predictors such as levels of demand and different generation types, which should become an important tool for system planning.

The two tools will work side by side to provide a real-time view of the GB power system and a world-leading inertia management capability, says National Grid.