Application Prospects of Flexible Low-Frequency AC Transmission in Offshore Wind Power Integration

Global offshore wind farm is developing towards large-scale, clustered and long-distance deep offshore. The transmission and grid connection of large-scale offshore wind farm with a distance greater than 100 km has become a major trend of offshore wind energy development. Research shows that flexible low-frequency alternating current (LF AC) transmission by reducing the frequency can not only realize the growth of the ampacity of cable, but also significantly reduce the charging current in the AC cable. Taking practical engineering as an example, this paper makes a technical and economic analysis of 3 grid connection modes: high voltage alternating current (HV AC) transmission, voltage source converter-high voltage direct current (VSC-HVDC) transmission and LF AC transmission. The demonstration shows that LF AC has both technical and economic advantages on large-scale and middle-long distance offshore wind farm transmission and connection system with the transmission distance of LF AC increasing.