|Manufacturer of conductor/cable||Alcatel
|Manufacturer of substations||ABB|
|Type of current||HVDC|
|Total length||240 km (150 mi)|
|Power rating||1,700 MW (Skagerrak 1–4)|
|Number of poles||4|
Cross-Skagerrak is the name of a high-voltage direct current (HVDC) transmission facility between Tjele (Denmark) and Kristiansand (Norway). It is owned and operated by Statnett in Norway, and Energinet.dk in Denmark.
The 240-kilometre (150 mi) Cross-Skagerrak 1–3 scheme consists of a 113-kilometre (70 mi) overhead line and a 127-kilometre (79 mi) underwater cable. It has a capacity of 1,050 megawatts (MW). Both land parts in Denmark and in Norway uses overhead lines from the cable landing point to the converter stations. The towers were originally constructed for four poles, but were rebuilt for three conductors (three poles) when Skagerrak 3 was established. Near Aggersund HVDC Cross-Skagerrak crosses Aggersund strait overhead on 70-metre-tall (230 ft) towers with a 470-metre-long (1,540 ft) span. The pylons of this span are the tallest electricity pylons of an HVDC line in Europe.
For such a long submarine cable, an AC transmission scheme would not be feasible since too much of the cable's capacity would be consumed by the capacitance of the cable itself.
Skagerrak 1 and 2
Cross-Skagerrak went in service in 1977 as a bipolar HVDC scheme. This facility was built with thyristor valves. When installed this underwater cable was the world's longest and deepest underwater HVDC power cable. The cable, manufactured by Alcatel, is laid in a maximum water depth of 530 metres (1,740 ft).
Both cables have a capacity of 250 MW at 250 kV.
In 1993 the scheme was extended by HVDC Cross-Skagerrak 3. Cross-Skagerrak 3 is a monopolar line for a voltage of 350 kV with a capacity of 440 MW at 350 kV. In installing Cross-Skagerrak 3, the old poles Cross-Skagerrak 1 and Cross-Skagerrak 2 were converted to monopolar HVDC schemes, which run with opposite polarity to Cross-Skagerrak 3.
In November 2009, Statnett and Energinet.dk signed the agreement to construct Skagerrak 4. Capacity of Skagerrak 4 will be approximately 700 MW. It has been in a test phase since 1 October 2014 and is expected to be operational by the end of 2014. As for the existing Skagerrak 1-3, the grid connection points will be Kristiansand and Tjele. Differently from Skagerrak 1–3, for Skagerrak 4 a cable solution is chosen for the complete route length. The 300 million DKK Prysmian land cable on the Danish side is approximately 90 kilometres (56 mi), while the 137 kilometres (85 mi) subsea cable and the 12 kilometres (7.5 mi) Norwegian land cable is to be made by Nexans for 638 million DKK. Converter stations will be built by ABB, as for Skagerrak 1–3. The combined budget is 2.8-3.2 billion DKK.
The technology used will be VSC, capable of black start. Although thyristor-based converters have a loss of only 0.7%, the IGBTs of VSC get close with a loss of 0.8 to 1%. Skagerrak 1 and 2 currently use Skagerrak 3 as a return cable, but 1 and 2 will be coupled so that Skagerrak 4 can use number 3 for returns.
|Tjele HVDC Static Inverter|
|Denmark Overhead Electrode Line Terminal|
|Aggersund Crossing Tower South|
|Aggersund Crossing Tower North|
|Danish Cable Terminal|
|Norway Cable Terminal|
|Norway Electrode Line Terminal|
|Norway Electrode Line Branch|
|Kristiansand HVDC Static Inverter|
- "Skagerrak 1-3 HVDC Interconnections". ABB. Retrieved 2011-02-13.
- "The Skagerrak HVDC Scheme". Bonneville Power Administration. Archived from the original on 2005-02-08. Retrieved 2011-02-13.
- "Submarine power cable to connect Jordan, Egypt". PowerGen Worldwide (PennWell Corporation). 1995-01-01. Retrieved 2011-02-13.
- "Kommersiell drift av SK4 utsatt" Statnett, 15 December 2014. Accessed: 16 December 2014.
- "Demark, Norway to build fourth interconnector". PowerGen Worldwide (PennWell Corporation). 2009-12-09. Retrieved 2011-02-13.
- Mikkelsen, Søren Damsgaard. Billion kroner cables Energinet.dk, 7 January 2011. Accessed: 9 January 2011.
- "ABB wins $180m order for Norway-Denmark power transmission link". PowerGen Worldwide (PennWell Corporation). 2011-02-11. Retrieved 2011-02-13.
- 130 mio. euro for new technology on Skagerrak 4 Energinet.dk, 10 February 2011. Accessed: 29 November 2011.
- Godske, Bjørn. New cable to Norway secures grid against faults (in Danish) Ing.dk, 11 February 2011. Accessed: 11 February 2011.