The HelWin 2 project is the third connection in the eastern region of the North Sea and is one of the 10 operated/owned by TenneT projects enabling the transport of offshore wind power. This 690MW grid link near Helgoland, which i to be operational as of spring 2015, will be able to power over 500,000 homes in Germany.

As part of this project, the HelWin beta platform will receive alternating current from wind farms and convert it into direct current before transporting it onshore through the subsea cable. The route of the grid connection runs 45 kilometers across land from the converter station in Büttel to the coast, and from the landing point in Büsum a further 85 kilometers directly to the offshore converter station.

Worthy of note is the fact that the HelWin 2 offshore converter platform will be directly connected to HelWin alpha with a bridge, in order to allow the common usage of the helicopter desk and the crew quarters.

In the course of the abovementioned project, Prysmian awarded ASDG with a subcontract for the loading, transfer to worksite, laying, protection and pulling in platform of the HelWin 2 subsea HVDC cable system. The SoW included the utilization of CLB 'Atalanti' for the loading of 2x68.3km of HVDC cables from Pikkala, Finland, 1x68.3km of FOC and 1x68km of LV cable in a single basket from Bremerhaven, Germany, and simultaneous laying and burial of the bundled cables using 'Hydroplow' underwater burial vehicle, from the shallow water section up to the end of the cable route. The SoW also included assistance to cable jointing operation with the previously laid shallow water section cable.

 

 

Project Specifications

HelWin 2

Year:
2014
Contractor:
Prysmian PowerLink Srl
Cable Type:
Power 2 x320kV HVDC & 1 FO & 1 LV bundled
Cable Weight:
Power: 32Kg/m FO: 3Kg/m LV: 0.267Kg/m in air
Cable Diameter:
Power: 117mm FO: 35mm LV: 11.5mm
Service Provided:
Cable Transportation - Simultaneous Laying/Burial
Laying Length:
67,426m
Owner:
TenneT
Jetting Length & Cover Depth:
47,401 @ 1.7m / 19,589 @ 1.5m
Location:
North Sea, Germany
Max Water Depth:
24m