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Accelerating Distribution Connections

Accelerating Distribution Connections Ahead of Transmission Reinforcement Works.

A key challenge faced across GB at present is the time being quoted to connect generation to the network due to the rapid expansion of the GB connections queue. At the end of 2023, about 500GW of generation was contracted to connect across GB transmission and distribution networks. For comparison, this is over eight times the GB electricity peak demand.

As a result of this rapid expansion of the GB connections queue, many of our GSPs now have connections subject to transmission works. Historically, customers could not be connected until transmission network reinforcements had been completed, with some customers currently having connection dates more than 10 years away.

As part of the Energy Networks Association’s (ENA) Strategic Connections Group (SCG), we have been working collaboratively with the Electricity System Operator (ESO), Transmission Owners (TOs) and the Distribution Network Operators (DNOs) to accelerate distribution connections through the establishment of Technical Limits on the transmission and distribution boundary. This allows DNOs to manage the flows at the interface points between the agreed limits and provide customers with a flexible connection on a temporary basis, ahead of transmission reinforcement works being completed. These accelerated connections will need to be managed through Active Network Management (ANM) and will be subject to uncompensated curtailment.

What are ‘Technical Limits’?

Technical Limits are operational limits agreed between the DNO, TO and ESO at the transmission and distribution boundary, to allow the DNO to manage the power flows at the Grid Supply Points (GSPs) and connect distribution customers at these GSPs ahead of transmission reinforcement works on a flexible basis.

Where are we rolling out Technical Limits?

As part of Phase 1A we have agreed Technical Limits at 4 of our GSPs in the SPM network, with offers issued to eligible customers enabling accelerated connection timescales. The accelerated connections timescales are subject to our Constraint Management Zones (CMZ) rollout plan for establishing ANM which will enable us to be manage the generation connections within Technical Limits.

We are currently working to further roll out Technical Limits at the remaining GSPs in our SPM network. We will be issuing an Expression of Interest (EOI) to the eligible customers for each of the Tranches during 2024. 

Phase 1APhase 2 Tranche 1Phase 2 Tranche 2Phase 2 Tranche 3Phase 2 Tranche 4Future
BirkenheadConnah's QuayFrodshamCarringtonCellarheadTrawsfynydd
CapenhurstPentirInceFiddlers FerryRainhillWylfa
KirkbySt.AsaphLister Drive   

Within the SPD network we have been employing Load Management Schemes (LMS) as a way of connecting customers to the distribution network earlier and ahead of transmission reinforcement works. LMS is a system comprised of geographically distributed measuring devices and site-specific customer interfaces to detect, in real-time, unacceptable overloading of transmission assets to disconnect the generation contributing to the overload in accordance with contractual agreements.

Further information about LMS.

Customer Eligibility for Technical Limits

To be eligible to receive a flexible connection at a GSP managed through Technical Limits, you must:

  • Require the connection of a Small or Medium Power Station.
  • Have an accepted connection offer which is subject to the delivery of transmission reinforcement works on a GSP where Technical Limits have been established.
  • Be able to operate your connection in accordance with SPEN’s ANM requirements.
  • Be connecting to an existing GSP.

Frequently Asked Questions

Are there any works associated with the implementation of Technical Limits?

The implemention of Technical Limits requires an Active Network Management (ANM) control system to monitor and manage the power flow at the GSPs within the Technical Limits. SPEN will install an ANM control system at the relevant GSPs with Technical Limits. An ANM outstation will also be installed at the customer’s substation, which is funded by the customer, to interface with their generators enabling full visibility and control to DNOs.

Is my current connection target date improving with Technical Limits?

The target date of connection will be accelerated with Technical Limits and this is why they are being rolled-out. However, the target date will vary from customer to customer, depending on the customer’s connection arrangements and requirement for any distribution network reinforcement.

What happens if I do not accept my variation for Technical Limits?

You can decide on whether or not to proceed with your flexible connection under Technical Limits. Where you decide not to pursue a flexible connection under Technical Limits, your connection will proceed based on your accepted connection offer and you would not be able to connect until the transmission reinforcement works are completed.

Should you wish to proceed with a flexible connection under Technical Limits at a later date, this could potentially be offered however, you will be placed at the end of the Technical Limits queue.

How much curtailment am I likely to see?

SPEN provides an indication of the level of curtailment that the proposed connection may see under Technical Limits to aid customers in their decision making process. This is provided on an indicative basis only. The actual curtailment will be dependent upon the Technical Limits and the real-time net flows through the GSP, which in turn will depend on import/export flows from existing and future customers, and operational running arrangements of both the distribution and transmission networks.

The curtailment will vary from customer to customer and GSP to GSP. The variation offer provides you the indicative level of curtailment including:

o    Estimation of curtailment results in megawatt-hours (MWh);

o    Estimated half-hours curtailed in percentage.

How is curtailment calculated?

SPEN have produced a Guidance to Technical Limit Curtailment Assessments which describes the methodology followed to produce curtailment assessments for Technical Limits. The indicative level of curtailment will be reviewed on an annual basis.

Will my flexible connection under Technical Limits change my contributions to transmission works and associated securities?

An earlier connection under Technical Limits will not change the securities (cancellation), the transmission connection asset or reinforcement charges associated with the connection.

Useful links

How we're improving grid connections – Energy Networks Association (ENA)

Open Data Portal



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