Wind farm developers and operators are preparing to switch over to 66kV from the current 33kV to get lifecycle cost-efficiency benefits such as the possibility of reducing the number of substations required as well as reducing the length of cables that need to be installed.
The 66kV technology has been demonstrated in three pilot projects; the Blyth Offshore Demonstrator (UK), Nissum Bredning Vind (DK) and Aberdeen Bay (UK) wind parks, which are all successfully connected to the grid and generating power. Nexans has played an important role in these projects by supplying a range of products and accessories including 66 kV sea cables (array and export cables), power cable accessories (equipment bushings, connectors, coupling connectors, surge arresters, dead-end receptacles, junction cabinets), GPH connection technology and pre-assembled cables.
These are pilot projects and the experience and results obtained will have significant impacts on future offshore wind projects.
The Blyth Offshore Demonstrator, 6 km off the UK coast, is a pilot plant constructed by the Renewable Energies Division of the French energy group EDF. With a total capacity of 41.5 MW, produced by five V164-8.0 turbines from MHI Vestas Offshore Wind, it has produced low-carbon power for about 34,000 homes since January 2018. Nexans delivered pre-assembled cable jumpers to connect transformers and switchgear, sea cables for the array cabling and connectors to connect the array cables to the wind turbine switchgear.
The transformers were assembled with EUROMOLD bushings and surge arresters and pre-assembled junction cabinets, export cables and connectors to connect the wind park to the existing power grid were used. The cable lengths were pre-assembled and electrically tested at Nexans Power Accessories in Hof, Germany. The sea cables, with a diameter of 127 mm, were produced in Hanover and delivered in one continuous length in 2017.