Prysmian Group was awarded a contract to design, produce and install the power cable systems by 50Hertz Offshore GmbH for the West of Adlergrund offshore wind farm cluster in the German Baltic Sea. Longitude were instructed by Prysmian Power Link Services (PPLS) and AssoDivers to undertake a variety of engineering analysis scopes to support the installation of the 220kV high voltage alternate current (HVAC) cable installation. Longitude worked with PPLS, and several other interested parties such as MWS and other subcontractors to provide engineering support for various scopes including; joint laydowns for a range of water depths and a variety of vessels, mooring analyses, loading condition stability, deck layout arrangements, structural assessments and yard mobilization support.

West of Adlergrund: Project Overview

The connection projects will involve the design, supply and installation of 220kV HVAC cable between planned offshore wind parks, 40km north-east from the island of Ruegen to the Lubmin substation in North East Germany. The cable route includes approximately 90 km of submarine cable.

Longitude’s Scope of Work

Joint Deployment

  • Vessel and site specific shallow and deep water RAOs generation for laydowns using Skandi Neptune and 289 barge
  • Full dynamic analysis of the 220kV HVAC cable in OrcaFlex using displacement RAOs to assess all stages of the omega joint deployment including recovery, jointing and laydown stages at various locations
  • Dynamic analysis of joint at touchdown in OrcaFlex for deployment over stern chutes

Installation

  • Second end pull in dynamic analysis for the cable that will be installed on the 50Hz platform for the Wikinger OWF
  • Assessment of cable protection system (CPS) fatigue life
  • Shallow water and alongside mooring analyses

Infield Joint Mobilisation

  • Deck layout arrangement
  • Foundation and equipment seafastenings design and assessment
  • Lifting beam modifications design and structural assessment

Onsite Support

  • Field team onsite to survey vessels
  • Dedicated onsite team to provide of yard support during mobilisations

Engineering Support

  • Dynamic adaptation to changing project requirements
  • Through-project engineering support and high level of flexibility due to parametric modelling and automation procedures implemented by Longitude meaning changes to original plans could be implemented with limited additional time and cost