Kensal Green 400kV GIS Substation

First use of compact GIS switchgear with double bus bar in a U-formation in the UK

Part of National Grid’s project to future proof London’s energy supply

Bespoke solutions to work with the limited spatial confines of the site

Cost savings through customised designs 

Client: National GridMorgan SindallInternational OEM
Value: £37m

First of a kind

A complex and first of a kind project, the new 400kV GIS substation at Kensal Green will help London meet increasing electricity demand and access renewable energies. Built as part of National Grid’s seven year project to rewire London via 32km of deep underground tunnels carrying the HV cabling that connects new and existing substations, Kensal Green was one of the new 400kV substations constructed. It saw the first use of compact GIS switchgear with a double bus bar in a U-formation in the UK, enabling the new substation to be constructed within the confines of the existing site.

BakerHicks provided architectural, civil and structural engineering and HV cabling design services on the project, including:

  • Design of the new GIS building, CSE structures, amenities building, Distribution Network Operator’s (DNO) building and their foundations
  • Design of surface water drainage system, security fence foundations, new access roads and foundations of water tank and flood pump house
  • Design of HV cables for Network Rail connections, in-situ HV underground cable troughs, LV cables, communications and services duct systems, and HV support structure for London Power Tunnel circuits
  • 3D structural analysis and Finite elements analysis
  • Management of National Grid verification and assurance process for all drawings and calculations

Bespoke solutions

A UK-first, the use of compact GIS switchgear created a number of design challenges for the HV cables and their support structure to limit the thermos-mechanical forces in play. To help overcome this, our engineers designed secondary steelwork to support the GIS and control building over-cladding. Programme constraints also required the GIS equipment to be installed before the over-cladding, so our experts developed a stub solution to allow this to take place and enabling the build to remain on-track.

Working within the limited spatial confines of the existing substation and with planning permission restrictions in place, the design was carefully coordinated in order to facilitate construction. The congested nature of the site also required bespoke design solutions to a number of elements, including the single pile foundations for the category two fencing and the complex shapes and layouts designed for the in-situ cable troughs and Cable Sealing End structural foundation design. These one-off solutions allowed the new substation to be constructed without impacting the existing site.

With planning permission restrictions in place, the design is sympathetic to the surrounding area to allow for future development. Architectural features such as false walls and doors were built into the design to ensure the DNO building met the planning requirements. Many of these features required bespoke civil and structural designs, our multi-discipline team worked collaboratively to produce solutions that support the architectural and planning requirements.

The project was completed to schedule and safely, delivering a key element towards securing London’s electricity supply.