UK, London: National Grid has launched its North West London Upgrade (NWLU), a major transmission programme designed to strengthen network resilience and create capacity for new electricity connections across London, Hertfordshire and Bedfordshire.
The programme stretches from Sundon substation in Bedfordshire through Elstree in Hertfordshire to St John’s Wood in London. It includes new and upgraded substations, cable infrastructure and reinforcement of existing overhead transmission lines.
At Elstree, National Grid will extend the existing 400 kV GIS substation and build the new 132 kV Letchmore Heath GIS substation. Together, the works will enable connections for five new data centres with combined demand of 1 GW.
The project also includes a new 400 kV cable circuit between Elstree and St John’s Wood. Around 60 km of new cable will be installed within the existing 20 km transmission tunnel, which was originally designed to accommodate an additional circuit.
Between Sundon and Elstree, National Grid will reconductor a 35 km overhead-line route, involving upgrades to more than 200 km of overhead conductors. Reinforcement works are also planned at Sundon and St John’s Wood substations.
Laing O’Rourke will deliver substation works at Letchmore Heath, Elstree and St John’s Wood, while Hochtief-Murphy Joint Venture will carry out cable installation and tunnel upgrades. Hyundai Electric will supply and install transformers and other major electrical equipment, and Siemens Energy will provide shunt reactors at Elstree.
National Grid said the programme will increase transmission capacity, support future electricity demand and reduce network constraint costs.
Source: National Grid
