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.

We understand generators working under the Accelerated Loss of Mains Change Programme may be restricted by Coronavirus. If you are struggling to meet the deadline, keep in touch for updated advice to be published shortly.

Constraint Management requirement notifications 2021

East Anglia / North London August 2021

Constraint Management requirement notifications 2021

Estuary July-Aug 2021

Static Reactive Power - Pennine - 2024-2034

10 November 2021 - We have updated the Tender Information Pack confirming commercial submission documents and an updated legal agreement as the words "Settlement Periods" were excluded in the drafting of clause 14.1.1.

29 October 2021 - We have sent out a communication highlighting changes to the Pennine Reactive Power Contract Terms and Commercial Assessment Methodology. We have also provided clarity on documentation for the Programme Capability.

30 July 2021 - We have updated the FAQs, please see v1.4 below and issued an updated Pennine tender information pack (v1.2) to clarify the definition of liquidated damages

07 May 2021 - We have updated the FAQs, please see v1.3 below

29 April 2021 - We have published the West Yorkshire MVAr absorption at Transmission sites Analysis below

23 April 2021 - We have updated the FAQs , please see v1.2 below

21 April 2021 - We have issued an updated Pennine tender submission proforma to include Greystones as an option on the Transmission worksheet.

6 April 2021 - We have issued an updated Pennine tender information pack (v1.1) to clarify the effectiveness values found on slide 29.


A tender has been launched for reactive power services to meet a static need in the North East England and West Yorkshire areas of the Pennine region. The 10 year contract will start from 1 April 2024. The tender pack is below. You can make a technical submission up to 14 May 2021 to our mailbox [email protected].  

If you have any queries, please use our new mailbox [email protected].  

Constraint management requirement notifications 2021

East Anglia / North London August 2021

Reactive Power Mersey 2021/22

Please note we have provided an update in the letter below to the EOI responses that were received in Sept 2020 for the Short Term Static Reactive Power service for the Mersey Region.

An Expression of Interest (EOI) has been launched for a Reactive Power service to meet a static need in the Mersey region. The 1-year contract, starting 1st April 2021 with the potential for additional months. Please can you inform your interest by the 22nd September by responding to the EOI to [email protected]

Stability Pathfinder Phase Two - Scotland 2020

Updated 30 September 2020


We have published the Expression of Interest (EOI) for Stability Pathfinder Phase 2 which is our next step in finding new ways of keeping the grid stable and focuses on our long-term requirements in Scotland. This EOI invites providers to submit their proposals on possible solutions which would then be assessed. If successful, providers would then invited to carry out a feasibilty study ahead of the commercial tender. 

The EOI and associated documents can be found below. The deadline for responses is the 8th January 2021 and these must be sent to [email protected].


We will hold a series of webinars, details of which can be found in the Stability Pathfinder Phase 2 EOI V1 document.

Static Reactive Power - Mersey 2022 - 2031

11.12.20 Please find an updated results letter and table for the Long Term Mersey Reactive Service tender 2022-31 and Lessons Learnt from the Mersey Pathfinder.

22.05.20 Please find the results letter and table for the Long Term Mersey Reactive Service tender.

20.03.20 Please see latest update for the tender participants for the Long Term Mersey tender

13.03.20 We have provided an update for the tender participants for the Long Term Mersey tender.

28.02.20 We have provided an update for the tender participants for the Long Term Mersey tender and an updated contract terms below.

31.01.2020 We have updated the Long Term Mersey Tender in the Invitation to Tender documents below.

Note: Please direct all queries and tender submissions to [email protected]

We have launched a long term tender for a Reactive Power service to meet a static need in the Mersey region. The 9-year contract, starting 1 April 2022, is part of a new approach to procuring reactive power to determine whether a third party can deliver a more economic solution compared to the network asset alternative. This tender is open to potential providers embedded within the Distribution network as well as at Transmission level, including those that are not yet connected.

Stability Pathfinder Phase One - GB 2020

Last Updated 17/04/20

Thank you to all those who have participated or have taken an interest in Phase One. This tender is now complete and moving into the service delivery phase with contracts signed with the successful providers. The tender timeline was consciously ambitious for both providers and NGESO, and with an extension to the tender window and further due-diligence necessary ahead of signing contracts, has taken longer than initially anticipated. This has impacted the development of Phase Two and consequently we are not quite ready to publish an expression of interest (EOI) yet. We are now feeding lessons learnt from Phase One into the development of the timeline and approach for Phase Two. We are also now considering the potential implications of coronavirus on both our internal process and timelines, and the capability of prospective providers to participate in the next stage of procurement. Our system needs have not however diminished, and so we intend to commence Phase Two procurement later this quarter (Q2’20) with further details to be published as soon as possible.

Reactive Power - Mersey 2020/21

A tender has been launched for a Reactive Power service to meet a static need in the Mersey region. The 1-year contract, starting 1st April 2020, is part of a new approach to procuring reactive power including potential new providers. This tender enables embedded assets, for the first time, to participate in a tender to solve a transmission voltage system need.

Scotland Enhanced Reactive 2019

A tender has been launched for Enhanced Reactive Service in Scotland. The tender is to allow the Electricity System Operator to access reactive power capability beyond Grid Code Obligations. In this tender the focus is on reactive capability available when active power output is less than 20% of the rated active power output of the unit. 

South Wales and Mersey 2019/2020

Request for Information

3rd October 2018 - We have published a Request for Information for the provision of Reactive Power Service in both South Wales and Mersey areas. The Request for Information forms part of our commitment in the Product Roadmap for Reactive Power. Interested reactive power providers are requested to submit information with an outline of their capability by the 5th November as detailed in the Request for Information. Please use the South Wales Proforma or Mersey Proforma in response to the RFI. 

Next steps update

4th December 2018 - The next steps for Request for Information for the provision of Reactive Power Service in South Wales and Mersey are published. Thank you to all providers who responded to the RFI, the information provided helped to shape the next steps of the RFI. The next steps can be found here for South Wales and Mersey

Tender

Following the publication of the Request for Information for the provision of reactive power services published on the website on the 3rd October 2018 and the update published on the 4th December 2018, please see below information regarding the next steps for the tenders in South Wales and Mersey

For Information: Vector Shift - Loss of Mains Protection change

FAO: Distributed Generators: Loss of Mains Protection change, away from Vector Shift (VS)

In order to preserve the stability of the electricity system, loss of mains (LoM) protection settings on a limited volume of existing generators fitted with Vector Shift (“VS”) type protection must be changed immediately in targeted locations across the south of England.

In order to encourage your support, the transmission system operator (TSO) and distribution network operators (DNOs) have agreed to a compensation proposal outlined in the open letters on this page, subject to generating units meeting the relevant criteria.

  • Is your site located in the SSE, UKPN or WPD DNO areas?
  • Is your distributed generation scheme sized at >1MW?
  • Is your protection afforded by a discrete G59 relay which utilises Vector Shift as its loss of mains protection?

Context and additional information is outlined in the open letters below.

Results

181 submissions were submitted to the DNOs and assessed by us. These sites accounted for over 1.3GW of Vector Shift capacity. All applications were ranked by their effectiveness at reducing the Vector Shift capacity at risk of trip, accounting for the cost, location, capacity and load factor during risk periods of each.

Two applications with incomplete information were excluded from the assessment.

Submissions from 71 sites, with a combined capacity of 811MW, met the assessment criteria and fulfilled our requirement at least cost to the consumer.