By laying in the first power cable between the monopiles “SB 28C” and “SB 29C”, Vattenfall and Stadtwerke München (SWM) have started the inter array cabling of the Sandbank offshore wind farm, 90 km west of the coast of German island Sylt.
Approximately 96 km of cables are to be installed within the wind farm. The cables are produced by JDR Cables in Hartlepool, Great Britain. The main contractor of the inner park cabling is VBMS, based in the Netherlands.
The cables contain an optical fiber that not only allows for the data exchange between each wind turbine and the offshore substation, but also the remote control and surveillance of the wind farm by the Vattenfall Control Center in Esbjerg, Denmark.
The cables are placed on the seabed and later they are injected at a minimum depth of 0.6 meters up to more than a meter into the bottom of the North Sea. This work is implemented by the cable-laying vessel Stemat Spirit . The vessel also transports the cables from Great Britain to the Sandbank offshore construction site.
The wind farm’s offshore substation is currently being built by companies in Denmark, Poland, and Germany, the responsible main contractor being Bladt Industries A/S of Denmark. Within the offshore substation, the power produced by the wind turbines is transformed from 33 kilovolt to a voltage level of 155 kilovolt. Then it is passed on to the converter station SylWin alpha.
The investment costs for the offshore wind farm Sandbank are around EUR 1.2 billion. Vattenfall holds a 51% stake in Sandbank Offshore Wind GmbH, which was set up to implement the project, while SWM holds a 49% stake.
Sandbank will feature 72 Siemens 4MW wind turbines, providing a total installed capacity of 288 MW. The wind farm is planned to be fully commissioned in 2017.
Image: Vattenfall