Western HVDC Link
Domestic ReinforcementOperationalGB2,250 MW600 kV422 km2017
Also known as:WHVDC, WHVDC Link, WHVDC Link bipole, Western Link, Western Bootstrap
Status:Operational
Capacity:2,250 MW
Project Company:
NGET/SPT Upgrades Ltd
Type:domestic reinforcement
Expected Life:40 years
Website:www.spenergynetworks.co.uk
Western HVDC Link is a bilateral GB transmission reinforcement comprising a circa 2.25 GW bipolar HVDC subsea cable and converter stations connecting Hunterston (North Ayrshire/Scotland) to the Deeside/Connah’s Quay area (Flintshire/North Wales). Its strategic purpose is to increase transfer capacity across key transmission boundaries (notably B6, B7 and B7a), support...
Supply Chain (9)
Project Timeline (19)
20 Dec 2025Geophysical Survey Complete
The December 2025 geophysical campaign for the Western HVDC Link was completed on or about 20 December 2025 (subject to weather windows). The MV Scotia operated 24 hours to capture multibeam and ROV cable-detection data across designated locations; results were used to confirm cable integrity, burial depths and to inform any necessary follow-up inspections or interventions.
5 Dec 2025Geophysical Survey Start
A geophysical survey campaign along the Western HVDC Link cable route commenced on 5 December 2025, carried out by the survey vessel MV Scotia at 14 locations in the Firth of Clyde, North Channel and northern Irish Sea. The scope included ROV-based cable detection, multibeam echosounder mapping and marine mammal observations to assess seabed and cable condition ahead of routine inspection or maintenance activities.
5 Nov 2023Geophysical Survey Complete
The geophysical inspection campaign that started in October 2023 concluded on or about 5 November 2023 (weather permitting). The survey delivered multibeam and side-scan sonar data across the route to assess cable burial, identify seabed changes and record any features requiring follow-up intervention or monitoring.
2 Oct 2023Geophysical Survey Start
A detailed geophysical inspection survey along the operational WesternLink submarine HVDC interconnector began on 2 October 2023. The campaign — executed by dive-support vessel Curtis Marshall — mapped parallel survey lines along the cable route using multibeam echosounder and side-scan sonar to verify seabed condition, burial integrity and detect any exposures or anomalies along the full length of the 390 km route.
22 Nov 2019Commercial Operations Full Power
The Western HVDC Link reached full commercial handover on 22 November 2019, marking formal transfer to the operating parties and completion of commissioning activities required to deliver full commercial service. Prior to handover, the link’s full technical capability was progressively enabled (reported as ‘full use available’ from 16 October 2018 and providing full service by summer 2019); the completed link operates at a rated capacity of about 2,200 MW and was formally handed over to the operators to enter full commercial operation on 22 November 2019.
16 Oct 2018Onss Commissioned
After staged commissioning and remedial works, the Western HVDC Link was made available for full use on 16 October 2018. This milestone followed further work at the Hunterston converter site and represented the completion of key converter/substation commissioning activities required to operate the link at its intended capacity.
7 Dec 2017First Power
The Western HVDC Link (Western Link), a joint project delivered by SP Transmission (SP Energy Networks) and National Grid Electricity Transmission, was energised and entered service on 7 December 2017 at reduced capacity. Initial operation began with an approximate 900 MW capability while final commissioning works continued at the Hunterston converter site. The energisation brought the subsea HVDC connection between Hunterston (Scotland) and Flintshire Bridge/Connah’s Quay (Wales) into service so that power could begin to flow bi-directionally across the link to support north–south transfers of low‑carbon electricity.
7 Dec 2017System Testing
SP Transmission and National Grid placed the Western HVDC Link into service on 7 December 2017 at a reduced capacity (circa 900 MW) while further commissioning work at the Hunterston converter station continued. The partial energisation allowed the subsea HVDC link between Hunterston (Scotland) and Flintshire Bridge (Wales) to begin transmitting power during an extended commissioning and testing programme, while remaining works at the Hunterston onshore converter were completed.
2017Joint Venture Formed
SP Transmission (SP Energy Networks) and National Grid Electricity Transmission established a joint delivery and operating arrangement for the Western HVDC Link, a £1.2 billion, 2,200 MW bi‑directional subsea HVDC electricity link between Hunterston (Scotland) and Flintshire Bridge (Wales/England). The partnership delivered, commissioned and operated the asset, which entered commercial operation in 2017 to enable large‑scale transfer of Scottish renewable generation to England and Wales and to strengthen GB transmission capacity.
22 Aug 2016Cable Installation Complete
On 22 August 2016 contractor vessels completed Campaign 1 of the Western HVDC Link subsea cable works. The Giulio Verne recovered a 28 km wet‑stored section, joined it to the installed cable, laid it on the seabed and completed burial works; post‑lay survey activity by support vessel Go Pegasus was then scheduled. Notices to mariners and contractor progress updates recorded the recovery, jointing, laying and burial as completing the first installation campaign along the route.