Transmission Clusters in Northern Ireland – Optimising the Connection of New Renewable Generation

Northern Ireland has to date taken a developer-led approach to connections. Network operators must deal with each generator application on an individual basis, issuing offers within 90 days.

This approach worked well in the past, however it increasingly leads to network planning which is reactive rather than proactive, and therefore inefficient. A new approach is required.

The Northern Ireland transmission network was designed to efficiently transfer power from a small number of large power stations – not to facilitate numerous connections of geographically dispersed renewable generators. Connecting to the existing transmission system is therefore challenging due to a rapidly diminishing number of available substation bays, and limited network capacity during periods of high renewable generation output.

SONI, Transmission System Operator (TSO) for Northern Ireland, has developed a new

Transmission Cluster policy. This policy will allow anticipatory development of new, large scale transmission infrastructure to connect and integrate renewable generation. These new

Clusters will be designed to maximise network access from the outset, reducing the need for further network reinforcement.

The key aim of this policy is to deliver infrastructure ahead of need, with costs initially borne by the network owner. Upon connection, generators will pay this development cost back in proportion to their use of the capacity created. This paper details the design of this Policy, and an example of its implementation.