Hornsea Offshore Substation

Kent completed the concept design and detailed design of three offshore substation platforms for DONG Energy’s Hornsea wind farm project and is now undertaking fabrication and installation support.

The OSS (Offshore Substation) locations are in the UK, approximately 120km off the coast of Yorkshire. Water depths in this area are 31.5, 29.1, and 17.7m, w.r.t. LAT. The Hornsea substations all consist of a steel topside installed on a piled jacket foundation.

The three OSS (3x400MW) function as collector stations from where export cables run to one Reactive Compensation Substation, from where the power is sent to shore. The three OSSs are inter-linked by HV cables to secure redundancy.

The OSS functional requirements are as follows:

• Carry equipment for high voltage transmission and distribution and other facilities such as diesel generator, batteries and panels for wind turbine control;
• Only be manned during service and repair work;
• All control and monitoring will be carried out from the onshore control station;
• The OSSs will have an emergency shelter and welfare facilities for a maximum of 12 persons,
• During commissioning the OSS shall be equipped with lifesaving appliances to allow for a maximum manning of 24 persons; and
• The primary access will be by helicopter.

The topside is built up as a multi-storey steel structure with five deck levels including the Roof Deck.

Kent successfully constructed this impressive structure in the North Sea. We devised the concept design, before the structure underwent fabrication and installation.