We’ve connected three shunt reactors to help the system operator manage voltages, reducing emissions and saving costs for consumers

The equipment – large transformer-shaped devices called shunt reactors – help regulate the complex movement of energy in an alternating current (AC), a movement which is influenced by ‘reactive power’.

Reactive power can be added into the grid by switching in shunt reactors to keep voltage levels stable, giving the ESO’s control room extra tools at its disposal to manage the electricity system securely.

We’ve installed three shunt reactors at our Stalybridge, Stocksbridge and Bradford West substations, with further reactor connections planned across our transmission network over the coming years.

This innovative engineering solution supports the ESO’s safe and secure operation of the system into the future, with significant savings for consumers

The installation was designed, developed and managed in-house by our Infrastructure Development and Delivery (ID&D) team, with construction works delivered by our Asset Operations (AO) engineers, saving on contractor costs. 

Two reactors at Stocksbridge and Bradford West were able to start early in May 2024, and have operated on a near continuous basis since, with the Stalybridge reactor coming online in August.

Historically reactive power services have been provided in large part by thermal generators like coal and gas, but as these plants come off the system and the volume of renewables grows, the ESO needs new ways to manage the changing patterns of reactive power and maintain voltage control.

The new reactors will help its control room avoid using more expensive and polluting options to keep voltages stable in Northern England, reducing carbon emissions and saving costs for consumers.

“Making sure electricity supplies are stable and reliable is paramount as Britain’s energy system decarbonises,” said Jon Davies, director of network operations and intelligence at National Grid Electricity Transmission.

“Our installation of these shunt reactors on our network as part of this innovative project is an engineering solution that supports ESO’s safe and secure operation of the system into the future, with significant savings for consumers.”

Julian Leslie, director of strategic energy planning and chief engineer at the ESO, said: “Delivering new services that can produce the reactive power tools such as voltage management that we use on a daily basis to keep the electricity network stable and secure is paramount to delivering our 2025 ambition and to deliver net-zero.

“The continuous use of these shunt reactors since May demonstrates their incredible value for the electricity network and their importance in keeping bills down for consumers as we decarbonise the electricity system.”