Architecture and design of floating offshore substation for direct current applications

Duration: 36 months (2022-2025)


The increasing distance to the coast of future offshore wind farms and the energy losses inherent in this configuration make high voltage direct current (HVDC) an alternative and competitive solution. The design of floating substations operating with this technology raises a number of issues requiring R&D. These include defining the electrical components for HVDC applications in terms of weight, volume and sensitivity to float motion, as well as estimating the typical movements and vibrations of the structure. It will be crucial to design the HVDC dynamic cable and its connection system. A methodology will have to be defined regarding cyber security issues specific to floating offshore substations. In addition, the qualification process and the specifications of the required test infrastructure will have to be clarified.


To study the HVDC floating offshore substation as an integrated system through analyses of functional requirements, integration constraints, risk and reliability

Scientific and technical content

  • Design basis: global market analysis, definition of geographic sites and collection of metocean data, definition of farm and grid connection scenarios
  • Electrical systems and topside: functional analysis, electrical components list, electrical architecture definition, topside arrangement, calculation of the movements of the assembly
  • Semi-submersible platform: design, motion and vibration analysis
  • TLP platform: advanced and comparative design, motion and vibration analysis, basin testing
  • Dynamic cables: design of a cross section, definition of their arrangement and connection
  • Cybersecurity: architecture and mapping, risk analysis, mitigations measures
  • System integration: risk and reliability analysis, maintenance optimisation, OPEX calculation
  • Qualification: validation and qualification strategy, rules and regulation gap analysis, recommendations


AFOSS-DC project sheet (PDF)

Partners and financing

This project is led by France Energies Marines.

Total Energies logo
centrale mediterranee logo

The total project budget is €1,491K.

This project receives funding from France Energies Marines and its members and partners, as well as French State funding managed by the National Research Agency under the France 2030 investment plan. It also benefits fom financial support of Pays de la Loire, Occitanie and SUD Provence-Alpes-Côte d’Azur regions.

France 2030 logo

Photo credit: Yohann Boutin

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