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Carillion, Cilfynydd 400kV Substation

Morson Praxis were appointed by Carillion to deliver engineering support for the installation of a new shunt reactor bay at Cilfynydd 400kV Substation, forming a key extension to the existing high-voltage network infrastructure.

Client Brief

Supporting a Major Substation Expansion

National Grid commissioned Carillion to deliver a new 400kV, 200MVAr shunt reactor bay to enhance voltage control and network stability.
Morson Praxis were engaged to provide engineering design expertise for the new bay, which required full integration with the existing Main and Reserve Busbar 2 systems, including complex civil, protection, and control interfaces.

Project Overview

Integrating New Systems with Existing Assets

The project involved the installation of a new shunt reactor bay complete with associated civil works, mechanical and electrical interfaces, and protection and control systems.
Equipment for the bay included: 400kV 200MVAr Shunt Reactor, Alstom GL316X Circuit Breaker, Pantograph Disconnectors with Integral Earth Switches, Surge Arrestors, Current Transformers & Post Insulators, New bunds, plinths, and a noise enclosure, Extended electrified boundary fencing and New Protection & Control Relay Panels with DC Systems.

The new circuit was connected to an extension of the Main and Reserve Busbar 2 at the substation’s north-east corner, with the works delivered under carefully managed busbar outages to ensure minimal disruption.

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Powering progress through precision substation engineering.

Our Solution

Engineering Excellence in Complex Substation Environments

Morson Praxis’ engineering teams undertook comprehensive design and integration services, covering:

Full protection and control design
Remote end design and SCADA control modifications
Busbar protection and synchronising system upgrades
Electrical and mechanical interlocking for the new bay

All works were completed to National Grid standards, with seamless coordination between ABB (who supplied and installed the reactor) and Carillion. The project also included temporary works and delivery logistics to support the safe installation of the large reactor equipment.

Results

A Seamless Integration into the National Grid Network

The Cilfynydd 400kV Shunt Reactor Bay was successfully integrated into the existing substation network, enhancing voltage stability and operational reliability across the region.
Through Morson Praxis’ engineering expertise and collaborative approach, the project was delivered on time, safely, and to the highest technical standards, ensuring a future-ready expansion of the UK’s transmission infrastructure.