National Grid ESO Mersey Pathfinder

A new approach to managing voltage and reactive power

We’re finding new ways to operate the electricity grid which are more cost effective for consumers. In this blog, our Head of Networks Julian Leslie, outlines our new approach to managing voltage and reactive power, including our new contracts in the Mersey region.  

National Grid ESO Julian Leslie

What is reactive power and why is it important?

At National Grid ESO, we manage the electricity flowing across the transmission network from generation to demand. This electricity is transported at voltages much higher than what is delivered to your home. We must make sure that the voltage remains within safe limits across the whole network. We do this by using equipment and generators across the transmission system to absorb or inject reactive power. Too much reactive power increases voltage levels, and too little reduces it.

What’s changing and why?

Traditionally, reactive power services are provided by large generators and equipment owned and maintained by the transmission owner (TO). As we transition to a world where energy comes from low and zero carbon sources and access to large generators is reduced, we need to find new sources and providers of reactive power.

We have seen a continual increasing need to absorb reactive power and prevent high voltage levels. The Mersey High Voltage Pathfinder sought to find the most cost-effective solution to a need in the Mersey region. To deliver greatest value for the consumer, for the first time, we have compared new commercial providers of reactive power to a traditional asset provided by the TO. Partnership with the local distribution network operator (SPManWeb) also allowed providers on the distribution network to participate.

In total we received 15 applicants to the tender process and after a tough review process, we decided on the successful partners.

The pathfinder has today awarded contracts to commercial providers PeakGen and Zenobe (equipment and battery respectively). The total cost of the contracts is £8.67m over the nine-year term starting in April 2022 and represents the best value for the consumer.

The contracts will result in the building of a reactor which absorbs reactive power, and a battery which will be able to operate in additional markets alongside its reactive power contract.

How does this fit into the bigger picture?

A complex set of processes are involved in keeping the power system stable – ensuring secure and reliable operability in real-time. Currently those processes, the foundations of the electricity system, rely to some extent on the intrinsic nature of traditional fossil-fuelled generation.

Over the past year we have begun transforming these foundations, designing new approaches through our Pathfinder projects. New technology means that as well as wind and solar providing power, they can also be used to manage key properties of electricity such as frequency and voltage. We’re also designing new commercial frameworks too, widening access to the electricity market and making it easier for smaller, renewable sources of power to play a role.

New technology and a more intelligent use of energy is also playing its part, with recent examples, particularly in electric vehicle charging, helping to shift patterns of domestic electricity demand to accommodate increased levels of renewable power. Each little change means the grid is getting greener, and cheaper than the alternative option too, meaning savings are ultimately passed on to consumers.  

The progress is exciting, but the biggest change is yet to come – in just five years, when there is enough zero carbon generation available, we will be able to operate Great Britain’s electricity network without using any fossil fuels for electricity generation.