Transmission constraint management

Constraint management is required where the electricity transmission system is unable to transmit power to the location of demand, due to congestion at one or more parts of the transmission network. Here you can find out how to provide this service.

This service is geographically defined, so only certain providers will have the required technical capability to deliver the service.

If the system is unable to flow electricity in the way required, we will take actions in the market to increase and decrease the amount of electricity at different locations on the network.

25 November 2019 - We have published a tender for a 9 year Reactive Power Service contract in the Mersey region starting in April 2022. The Invitation to Tender, Information Pack and associated documents can be found on the Market Information tab. Technical data must be submitted by 17:00 on Friday 13th December 2019. Commercial tender must be submitted by 17:00 on 28 February 2020.

05 November 2019 - Potential providers are invited to tender for our first of a kind stability service. The Invitation to Tender Letter, Information Pack and associated documents can be found on the Market Information tab. Tenders must be submitted by 17:00 on Friday 29th November 2019.

14 October 2019 - We invite transmission or distribution connected providers to tender for the provision of a Reactive Power Service in the Mersey region from April 2020 - March 2021. The Invitation to Tender, information pack and associated documents can be found on the Market Information tab. Tenders must be submitted by 17:00 on Friday 8th November 2019.

Ahead of time contracts

We can enter into contracts to agree output with a service provider ahead of time.

  • Constraint management contracts enable us to agree in advance technical parameters with connected parties to facilitate the management of a constraint.
  • The most common style of contract is to agree either a cap or collar on the output of a power station.
    While other commercial tools are available to manage the output of a power station, constraint management contracts are considered where the cost of the action is more economic than other commercial tools.

There are multiple different styles of constraint management service that we may use to resolve a specific requirement.

Situations that can cause a transmission constraint

Import

The energy demand cannot be met by localised generation and the flow on the circuits into that area is limited by the capacity of the circuits; or into that area is limited by the capacity of the circuits

Export

The generation in the area is not offset by the localised demand and the flow on the circuits out of the area is limited by the capacity of the circuits

These constraints can be further broken down:

Thermal

Where the amount of energy that would flow naturally from one region to another exceeds the capacity of the circuits connecting the two regions.

Voltage

Where generation is needed in a particular area to support the local voltage.

Stability

Where particular circuit configurations have to be avoided because of the risk of oscillations in voltage or current.