Multi-terminal network options for the interconnection of offshore wind farms: A case study between Britain and The Netherlands

The increasing global energy needs have led to the realization of interconnectors to strengthen regional electricity systems. As interconnectors are often placed offshore, combining those with wind farm grids can increase profitability compared to separate infrastructure and improve the grid integration, offering higher security of supply and controllability. However, a systematic approach for selecting the best transmission options for offshore multi-terminal networks is still missing in literature. This paper investigates options for interconnecting two offshore wind farms (OWFs) to two onshore asynchronous grids in a multi-terminal network. The options are presented for a case study comprising the Dutch and the British grid along with two OWFs in the coastal zone of each country. A review of the available technologies regarding high-voltage ac (HVac) and high-voltage dc (HVdc) transmission systems is given and, on this basis, six technical scenarios are identified and evaluated. For each scenario, the technical specifications are elaborated and a rough cost calculation is made. Based on the design possibilities for a four-terminal network, the technical bottlenecks and the most important research challenges for its realization are presented.