Four electricity network companies have joined forces to replace the loss of mains protection systems for 800MW of distributed generation in the South of England.

The upgrades are expected to reduce network costs by £40 million annually.

Loss of mains protections are designed to take generators offline to prevent power islanding if the local electricity network is disconnected from the rest of the grid.

Modelling by National Grid found a standard protection system known as “vector shift” is highly sensitive to disturbances on the wider network and could cause generators, including wind and solar farms, to stop exporting power unnecessarily.

To resolve the issue, the firm teamed up with UK Power Networks, Scottish and Southern Electricity Networks and Western Power Distribution to fund the installation of a more resilient alternative at 70 sites across the region. The new system determines when to disconnect generators based on the rate of change of frequency.

Matt White, lead power system development engineer at UK Power Networks, said: “This is a standout example of partnership working, with the four utility companies coming together and successfully developing a solution for the benefit of all our customers.”

“There was a real imperative to make the short-term move to a more resilient type of protection in time for this summer, and we have come together to achieve it.

“The result means more renewable energy on the network and tens of millions of pounds saved in costs, which will ultimately save money for our customers.”