Seaway Offshore Cables
Nordsee One Offshore Wind Farm
Export Cable System
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Nordsee One OWF (ECS)

155kV Export Cable System

Seaway Offshore Cables was awarded the contract for the turnkey engineering, procurement, installation and commissioning (EPIC) of the 155kV grid connection system for the Nordsee One Offshore Wind Farm (OWF) project as part of the DolWin 2 HVDC grid connection system project in cooperation with J-Power Systems (JPS) by TenneT Offshore.

The Nordsee One OWF is situated approx. 40 km north of the island of Juist within the German Bight sector of the North Sea. The cable system consists of two 155kV high voltage alternating current (HVAC) 3-core submarine composite cables, which were installed in-between the offshore substation (OSS) of the Nordsee One OWF and the offshore converter platform (OCP) DolWin beta, as part of the DolWin2 cluster within the German exclusive economic zone (EEZ).

The HVAC submarine composite cables were manufactured and supplied by J-Power Systems (JPS) and were subsequently installed by Seaway Offshore Cables utilising dedicated in-house resources such as the Cable Lay Vessel Seaway Aimery and Installation Support Vessel Seaway Moxie.

Facts & Figures
  • 1 Offshore Converter Platform (OCP)

  • 15 km of submarine cables

  • 1 Offshore Substation (OSS)

  • 351 W2W Connections

  • 332 MW installed capacity

  • 1,394 Personnel Transfers

SOC was highly complimented by TenneT and Nordsee One in their professional, solution-oriented and flexible approach.”

Dániel Kajtár
Senior Electrical Engineer

The project presented a challenge with the HV jointing at the DolWin beta platform. SOC used out of the box thinking to find a solution at short notice with tight time and space constraints. Working safely and with the support TenneT, a total 32 HV terminations were installed between Nordsee One and DolWin beta to allow the grid connection to be energized on time.

Client: TenneT Offshore, Germany
Location: North Sea, German Sector
Water Depth: Up to 34 m
Scope: Supply of submarine composite cables
Supply of submarine cable accessories
Supply of cable protection systems
Supply of shunt reactors
Pre-lay grapnel run and route clearance
Cable installation, termination, testing and pre-commissioning
Type of Cables: 3-core submarine composite cable
Voltage Level: 155 kV
Conductor: Copper
No. of Cables: 2
Length of Cables: 15 km
Schedule: One (1) continuous campaign in 2016
Vessels: CLV Seaway Aimery
ISV Seaway Moxie
W2W Connections: 351
Personnel Transfers: 1,394

Website: TenneT

More information: 4C Offshore

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Lars Muck
Commercial Director