Heerema Installs Sofia Offshore Substation

August 29, 2024, by Adnan Memija

The high-voltage direct current (HVDC) offshore converter platform (OCP) has been installed at the Sofia offshore wind farm site in the UK.

The installation was carried out by Heerema Marine Contractors, using its Sleipnir heavy-lift vessel as a subcontractor to the GE Vernova/Seatrium consortium responsible for the OCP.

Credit: RWE

The platform, equivalent in height to an eleven-story building and weighing over 13,000 tonnes, was lifted onto the jacket structure, marking “the largest lift in offshore wind history”, RWE said.

“The successful installation of the OCP, the largest converter platform of its kind in the offshore wind industry, is a proud moment for RWE and everyone involved. This project not only highlights our commitment to leading the way on offshore wind, but demonstrates the scale and complexity of what can be achieved when we all work together”, said Sven Utermöhlen, CEO of RWE Offshore Wind.

The jacket structure, a welded tubular space frame, was first placed to support the topside facilities, which include supports for conductors, risers, and the topside itself.

The OCP topside took two and a half years to build and has required more than 13 million hours of work, according to RWE.

The platform was loaded out of the Batam yard in Indonesia and transported from there to the North Sea.

The use of HVDC technology is said to enable high-efficiency transmission of the wind farm’s electrical output, minimising power losses along the 220-kilometre cable route to shore.

The Sofia offshore wind farm is being built by RWE on Dogger Bank in the central North Sea, 195 kilometres from the North East coast of the UK, where monopile installation started in May this year.

The 1.4 GW wind farm will comprise 100 SG 14-222 DD wind turbines, of which 44 will be equipped with recyclable blades.

The renewable energy will be carried through subsea export cables to landfall in Redcar, Teesside, 220 kilometres away.

The Sofia offshore wind farm is scheduled to be fully operational in 2026, generating enough electricity to power approximately 1.2 million UK homes, according to the developer.