Horns Rev 3, Denmark

The Danish transmission system operator, Energinet, is an independent public enterprise owned by the Danish state. Energinet was looking for an AC (alternating-current) power cable system solution to integrate and transmit power from the Horns Rev 3 offshore wind farm.

The Horns Rev 3 wind farm is located in the North Sea, about 30 km off the western-most point of Denmark, Blåvands Huk, and not far from the city of Esbjerg. The 400 MW (megawatt) wind farm has the capacity to supply electricity to around 400,000 households.

In order to turn this ambitious energy project for a sustainable development into reality, Energinet had to establish a reliable power transmission link to the mainland.

The execution of such a demanding production and installation project requires great technical knowhow, excellent project management capabilities and extensive experience. We have a history of good partnership with Energinet and we had previously delivered high-voltage cables for several of their projects.

The renewable power generated by the offshore wind farm is brought to shore via this large 32 km long 220 kV (kilovolt) three-core polymeric insulated submarine cable with integrated fiber optics cables for data communications and temperature monitoring of the power cable.

Our project scope included the technical design, engineering, type testing and production of the high-voltage cable system including accessories and installation. It was the world´s second largest submarine cable with a diameter of almost 30 cm, and it weighed approximately 3,400 tons.

The entire cable system was manufactured at the state-of-the-art high-voltage cable factory in Karlskrona, Sweden. It was a challenge to produce continuous lengths of such a large cable, but everything went according to plan.

During the summer of 2016, the cable system was transported and pulled up to the offshore transformer platform and then laid on the seabed while gently moving towards land. The last part of the cablelaying was performed in the opposite direction due to the shallow waters.

Thanks to a great preparation work, the installation and the final test were successful. The project was finalized and handed over to Energinet according to schedule in June 2016.