National Grid ESO launches long term Mersey voltage tender

In April we shared our ambition to be able to operate the GB electricity system carbon free by 2025. In order to achieve that goal, we are finding new ways of managing system characteristics like voltage through reactive power services.

Today, Monday 25th November, we have issued a 9 year tender opportunity for reactive power absorption to solve a high voltage requirement in the Mersey region from 1st April 2022. This is the first time that we have offered a long term contract for reactive power and is part of a new approach to procuring the service from existing and new providers following on from the short term Mersey tender issued in October.

Reactive power services are how we make sure voltage levels on the system remain within a given range, above or below nominal voltage levels. Keeping the voltage steady requires careful management, a deviation as small as 5% above or below can have knock on impacts across the network, for example an increasing requirement to switch in and out our voltage control equipment more regularly and therefore increase the ongoing maintenance costs. We instruct generators or other asset owners to either absorb or generate reactive power. Managing voltage levels comes from maintaining a balance between elements on the system, which either absorb reactive power (decreasing voltage) or generate reactive power (increasing voltage).

The tender forms part of how the ESO is transforming how it manages transmission constraints, such as voltage, stability and thermal. The new approach aims to drive consumer value through determining whether there are more economic solutions to network asset investment. The tender is in two stages, a technical submission on 13 Dec ‘19 and commercial submission on 21 Feb ’20,