Western HVDC Link
| Western HVDC Link | |
|---|---|
| Location | |
| Country | United Kingdom |
| From | Hunterston, Scotland 55°43′16″N 4°53′7″W / 55.72111°N 4.88528°W |
| To | Flintshire Bridge, Wales 53°13′54″N 3°1′58″W / 53.23167°N 3.03278°W |
| Ownership information | |
| Partners |
National Grid plc ScottishPower Transmission |
| Construction information | |
| Manufacturer of conductor/cable | Prysmian |
| Installer of conductor/cable | Prysmian |
| Installer of substations | Siemens |
| Construction started | 2013 |
| Expected | 2017[1] |
| Technical information | |
| Type | Submarine power cable |
| Type of current | HVDC |
| Total length | 422 km (262 mi) |
| Power rating | 2,200 MW[1] |
| DC voltage | 600 kV |
The Western HVDC Link is a high-voltage direct current (HVDC) electrical link currently under construction between Hunterston in Western Scotland and Flintshire Bridge (Connah's Quay) in North Wales, routed to the west of the Isle of Man. It has a transmission capacity of 2,200 MW, and was expected to cost £1bn. The link entered operational service on 7 December 2017 at an initial reduced capacity of 900 MW pending further work at Hunterston.[2]
It consists of 422 kilometres (262 mi) of cable, of which 385 kilometres (239 mi) is underwater.[1] It is the first subsea link at 600 kV.[3]
There are two cables, which in shallow water are laid in a paired bundle, and in deep water laid about 30 metres apart, generally buried about 1.5 metres below the seabed. The cables are jointed in 120 km sections.[3]
Line commutated converter technology is used at each HVDC converter to maximise the capacity of electrical power, generated predominantly by renewable sources in Scotland, which can be transferred across the B6 boundary[notes 1] in parallel to two existing double-circuit AC transmission lines. This type of HVDC conversion technology means that large filter halls are required at each converter station.[4] Gas-insulated switchgear is used at the Hunterston converter station to save space.
Routing the connection through the Irish Sea as opposed to a land-based route limits the impact of the link on the visual environment and circumnavigates potential problems associated with the rising cost of land on the overall project costs. For the given distance, it is necessary to use a DC transmission technology for a subsea route, as the capacitive current required for an AC connection would be too high. Due to the proximity of converter stations to the coastline, a decision was taken to host electrical infrastructure within built structures in order to reduce the effects of the coastal air on sensitive electrical assets.
Power can be transferred in either direction (which might become more likely due to the closure of Longannet power station), but it is necessary for the link to be offline for a sufficient time prior to reversing the direction. Mass impregnated non-draining (MIND) cables are used in a bipolar arrangement, but no sea- or earth-return path is permitted for environmental reasons, meaning that both cables must be in service for the link to be operational. The cables are spaced apart to minimise thermal interference, but not so far as to materially impact any marine life which navigates using the magnetic field of the Earth.
Engineers working on the project discovered the almost intact wreck of the World War I German submarine UB-85.[5]
Notes
- ↑ The UK transmission grid is often analysed in terms of flows across fictitious "boundaries" which divide the network in two. Where the lines which across a boundary struggle to accommodate projected flows, the boundary needs strengthening. Though most boundaries do not correspond to geographic or political features, the B6 boundary runs along the England/Scotland border.
References
- 1 2 3 "Q&A". Western HVDC. Retrieved 28 March 2015.
- ↑ "Welcome". Western Link. Retrieved 5 December 2017.
- 1 2 "Marine cable". Western HVDC. Retrieved 28 March 2015.
- ↑ "Hunterston converter station & cable". Western Link.
- ↑ "Wreck of German U-boat found off coast of Stranraer". BBC. 19 October 2016.
External links
