Marine substation

The offshore substation was successfully completed in July 2022, being manufactured in Belgium by a joint venture between Smulder (a subsidiary of Eiffage Metal) and Equans, with former carrying out the engineering and construction of both the foundations and the platform that houses the transformers and other electrical gear, while the latter carried out their assembly and commissioning.

The structure supporting this substation comprises a foundation (jacket) 63 metres high and weighing 1,630 tonnes, and a platform 55 m long, 31 m wide and 23 m high, weighing approximately 3,400 tonnes. Over the course of 2022, the piles, cables and the electrical substation were installed. Offshore construction work was carried out during 2023 to integrate all the elements. 

Iberdrola awarded GE Renewable Energy Grid Solutions the supply and installation of the major electrical equipment for the substation. The company was. responsible for the design, construction, installation and commissioning of the high-voltage electrical equipment, as well as the control and protection system for the substation. To do this, it designed and manufactured the 72.5 kV and 225 kV gas-insulated switchgear (GIS) at its factory in Aix-les-Bains (France).

 Transport and installation

For its part, the Dutch maritime services company Van Oord was responsible for the transport and installation of the 62 jackets and the offshore substation. Van Oord started work on the open sea in 2021 with the installation of the anchor bolts, for which it deployed its high seas support boat, Aeolus, specifically designed for the construction of offshore wind farms, which was assisted by a second vessel from 2022.

 Cabling

As for the undersea cabling connection systems, they were provided by Prysmian Group, world leaders in the business of power cabling systems and telecommunications with whom Iberdrola has already worked on Wikinger and Vineyard Wind, which installed and commissioned 90 km of high-voltage 66 kV AC connection cables and three hubs with XLPE insulation.

Following tests carried out in summer 2020, the undergrounding of all cables between the wind turbines was confirmed, which is a giant step forward for navigational safety and for the continuation of fishing activity within the park. Delivery and commissioning were completed in December 2023.

 Communication and coordination

A consortium led by Atos – in partnership with SeaRenergy, a leader in engineering, marine solutions, QHSE and personnel services for the offshore wind industry – was responsible for implementing critical communication solutions and ensuring maritime coordination activities.

Specifically, a maritime coordination centre was set up in the coastal city of Pleudaniel (France) to coordinate, monitor and document all the movements in and around the construction area, 24 hours a day, seven days a week during the construction phase. They also established a unified critical communications platform that enables the helicopters, ships and operational teams working on the offshore wind farm to communicate with each other and with the coordination centre, within and around the park.

Both systems were retained after the construction phase and will support the wind farm throughout the operational phase.

In addition, in order to inform inhabitants, in particularly sea users, an online information service dedicated to the works was opened and compensation measures were put in place for fishermen whose activity could be affected during the construction phase.