First DolWin Kappa Steel Cut

Transmission system operator TenneT has cut the first steel for the DolWin kappa offshore converter platform, the centerpiece of the 900MW DolWin6 HVDC connection.


Spain’s Dragados Offshore is responsible for the design, supply, construction, transportation and installation of the DolWin kappa platform and the accompanying jacket foundation.

Siemens will supply the entire technology for the DolWin6 connection, as well as design and build an onshore converter platform in the region of Emden.

The 155kV alternating current supplied by wind turbines will be converted into 320kV direct current on the DolWin6 offshore platform and transported to Hilgenriedersiel on the mainland via a 45-kilometer subsea cable. On the ocean, the cable will pass underneath the island of Norderney by means of horizontal bore holes.

Once on land, the electricity will be transported by another 45-kilometer underground cable to Emden, East Frisia, where Siemens is building the converter station for converting the direct current back into three-phase current and feeding it into the high voltage grid. Nexans will supply the direct-current cables.

TenneT plans to have the 900MW DolWin6 connection commissioned in 2023.