Reactive power services

Reactive power services are how we make sure voltage levels on the system remain within a given range, above or below nominal voltage levels. 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).


Update: 16th May 2022 - Request for Information
Accessing Additional Voltage Capability 2023 - 2026

National Grid ESO are today issuing a request for information (RFI) to look at accessing additional reactive capability across England and Wales between 2023 and 2026. 

We are at a very exciting time in the electricity industry as we move to a decarbonised electricity system and as we transition, we need to think differently about how the network is operated. One of the key technical challenges is in voltage management. This RFI sets out the challenge that we see in the short to medium term and is asking for existing and new providers that are capable of providing additional voltage services to come forward and express an interest in participating in a potential voltage contract. 

Within the RFI we set out the technical need in multiple zones across England and Wales and explain what information we need in order to make an assessment and determine the next stage which if appropriate would be to run a commercial tender process. 

If you are a new or existing provider of voltage services where you believe you can offer a new or enhanced service, then please respond by 5pm on 13/06/22

RFI - Reactive Power Capability 2023-2026

Pro-Forma RFI Reactive Power Capability 2023-2026


We use the services set out below to manage voltage levels:

National Grid ESO - Early Competition Plan - Mermaid street

Obligatory reactive power service (ORPS)

Provision of varying reactive power output. At any given output generators may be requested to produce or absorb reactive power to help manage system voltages.

National Grid ESO - RIIO 2 business plan - Shard view from the river

Enhanced reactive power service (ERPS)

Provision of voltage support that exceeds the minimum technical requirement of the obligatory reactive power service (ORPS).

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Reactive Reform – Market Design

We are now exploring potential solutions to reform the reactive power services which will help to address the challenges we face for system voltage control.

Reactive power describes the background energy movement in an alternating current (AC) system arising from the production of electric and magnetic fields. Devices that store energy through a magnetic field produced by a flow of current are said to absorb reactive power; those that store energy through electric fields are said to generate reactive power.

The flows of reactive power on the system will affect voltage levels. Unlike system frequency, which is consistent across the network, voltages experienced at points across the system form a 'voltage profile', which is uniquely related to the prevailing real and reactive power supply and demand. We must manage voltage levels on a local level to meet the varying needs of the system.

Without the appropriate injections of reactive power at the right locations, the voltage profile of the transmission system will exceed statutory planning and operational limits.