Cross-Skagerak

Cross-Skagerak is the name of an high-voltage direct current (HVDC) transmission facility between Tjele (Denmark) and Kristiansand (Norway).

kagerak 1 and 2

Cross-Skagerrak went in service in 1977 as a bipolar HVDC scheme. This facility was built with thyristor valves. In its initial configuration it had a capacity of 1000 megawatts (MW) across a distance of convert|250|km|mi. The convert|230|km|mi line of Cross-Skagerak consists of a convert|100|km|mi overhead line and a convert|130|km|mi underwater cable. When installed this underwater cable was the world's longest underwater HVDC power cable. The cable is laid in a water depth of convert|500|m|ft.

kagerak 3

In 1993 the scheme was extended by HVDC Cross-Skagerak 3. Cross-Skagerak 3 is a monopolar line for a voltage of 350 kV with a capacity of 500 MW. In installing Cross-Skagerak 3, the old poles Cross-Skagerak 1 and Cross-Skagerak 2 were converted to monopolar HVDC schemes, which run with opposite polarity to Cross-Skagerak 3.

Technical features

HVDC Cross-Skagerak uses electricity pylons with three conductors, mounted on pylons with two crossbars. In Denmark these pylons are designed for carrying a fourth conductor. Near Aggesund HVDC Cross-Skagerak crosses Aggesund strait overhead on tall pylons with a convert|470|m|ft long span.

The use of three underwater cables allows the interchange of hydroelectric power, thermal generation, and wind generation between Norway and Denmark, allowing overall lower cost of electricity production. For such a long underwater 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. HVDC makes long underwater power transmission cables economically feasible.

kagerak 4

In June 2008, the Norwegian transmission grid operator Statnett and the Danish transmission grid operator Energinet.dk agreed to construct Cross-Skagerak 4 submarine cable. The capacity of the new cable will be 600 MW and it expected to be operational by the end of 2014. The cable consists of two substations in Kristiansand and in Tjele. The land cables on the Danish side are approximately convert|90|km|mi and in Norway, a combined cable and overhead line is approximately convert|30|km|mi.cite news
url = http://www.energinet.dk/en/menu/News/Newsarticles/The+electrical+interconnections+to+Norway+and+Germany+to+be+expanded.htm
title = The electrical interconnections to Norway and Germany to be expanded
publisher = Energinet.dk
date = 2008-06-17
accessdate = 2008-06-24]

References

External links

* [http://www.statnett.no/Files/Open/c_hvdc_skagerak3.pdf Description of Cross-Skagerak 3]
* http://www.transmission.bpa.gov/cigresc14/Compendium/SKAGERR.htm
* http://www.transmission.bpa.gov/cigresc14/Compendium/Skagerr%20Pictures.pdf
* [http://www.abb.com/GLOBAL/GAD/GAD02181.NSF/viewunid/C1256D71001E0037C1256C7900298FF1!OpenDocument&v=17EA&e=us The ABB Group]