E.ON has installed the electric offshore transformer station of the 385 MW Arkona offshore windfarm in the German Baltic Sea.

The station has been successfully installed at a water depth of almost 30 meters, 35 kilometres northeast of the island of Rugen.

Moving the topside from a barge onto the foundation with the crane ship Oleg Strasnov marked the installation of the world’s heaviest alternating current platform, which had previously been lifted in one block out at sea.

The largest single component of the €1.2bn project, the transformer weighs more than 5000 tonnes and consists of the jacket foundation anchored in the seabed and the topside with the electrical switchgear and transformers.

It is the size of an eight-storey building and has a helipad at an altitude of 70 metres above sea level. The construction of the transformer station at the French shipyard STX required more than 500,000 working hours.

The Arkona windfarm is a joint venture between E.ON and Statoil who will use the platform with the transmission grid operator 50Hertz. It will export power to the grid via the 93km Ostwind 1 cable system and 50Hertz’s onshore substation in Lubmin.

The unmanned station is located in the middle of the construction site of the windfarm and will bundle the electricity produced by 60 of Siemens’ 6 MW wind turbines, which is then transported to the mainland by sea cable.

The substation is operated from the operating station of the windfarm in the port of Mukran Port in Sassnitz on Rugen island, while E.ON’s Offshore Marine Coordination Centre in Hamburg monitors and controls the operation.

The next step in the construction phase will be the laying of the internal parking cabling. This will be followed in late summer by the installation of the wind turbines on the foundations. The complete commissioning of the entire windfarm is planned for 2019.

VIDEO: Arkona transformer substation