Low Frequency AC transmission for offshore wind power: A review

This paper provides a review of Low Frequency AC (LFAC) transmission, which is of significant interest for offshore wind farm integration at a range of 80-180 km. LFAC is an adaptation of HVAC transmission, operated at lower frequency, typically 16.7 Hz. The key advantage of LFAC compared to HVDC is the elimination of the requirement for an offshore converter station, thereby reducing offshore complexity and potentially increasing the operational life of the offshore wind farm. Design challenges are introduced surrounding the design of the 16.7 Hz transmission transformer and associated offshore platform for this potential transmission technology. A comprehensive review of existing research conducted on LFAC and a discussion centreing on the design considerations for offshore LFAC transmission components is presented. The frequency changing converter onshore, offshore LFAC substation and the wind turbine considerations are evaluated in detail. LFAC multi-terminal offshore grids are also considered, as this alternative to HVDC multi-terminal grids may reduce the requirement for multiple offshore converter stations.