Cross Skagerrak

Historie

Skagerrak is the name of a 1,700 MW 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 lines connect the hydroelectric-based Norwegian grid and the wind and thermal power-based Danish grid. In operation it enables more renewable energy in the energy mix, and more efficient use of electricity.Technical featuresThe 240km Skagerrak 1–3 scheme consists of a 113km overhead line and a 127km 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 overhead lines in Denmark are set to be renovated in 2016 for increased lifespan. The towers were originally constructed for four poles, but were rebuilt for three conductors (three poles) when Skagerrak 3 was established. Near Aggersund HVDC Skagerrak crossed Aggersund strait overhead on 70m towers with a 470m span, but were later converted to underground cables. The pylons of this span were 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, and the power systems in Norway and Jutland are not synchronous.The transmission has a loss rate of 4%.