The Completion of DolWin5 Grid Connection Marks Milestone for Offshore Wind Energy

The laying of the subsea cable that connects the DolWin epsilon platform to land has been completed. The platform and the cables, part of TenneT’s DolWin5 grid connection, will transmit the electricity generated by Ørsted’s Borkum Riffgrund 3 offshore wind farm to the German grid on land.

The DolWin epsilon platform was installed this June. The export cable was installed by the cable supplier Prysmian using Jan De Nul’s vessel Isaac Newton. Prysmian has delivered the connection under an EPCI contract with TenneT, which includes design, procurement, construction and installation.

The DolWin5 offshore grid is scheduled to be connected to the German national grid later this year.

Power Transmission Technology

The 900 MW offshore grid connection uses extra-high voltage direct current (HVDC) transmission technology. The three-phase alternating current (AC) generated by the Borkum Riffgrund 3 offshore wind farm will be converted into direct current (DC) at DolWin epsilon and transported south to Hamswehrum near the river Ems in East Frisia via the 100-kilometer-long subsea cable.

From Hamswehrum, a 30-kilometer-long onshore cable leads to the converter station in Emden/East where the DC will be converted back into three-phase AC and fed into the extra-high voltage grid on land.

Wind Turbine Installation

Wind turbine installation at the Borkum Riffgrund 3 offshore wind farm was completed in January this year.

Borkum Riffgrund 3 comprises 83 Siemens Gamesa 11 MW turbines and, with a capacity of 913 MW, is Germany’s largest offshore wind farm.