Construction of offshore wind farms has become the trend of exploitation of wind power incoastal areas in China. For improving efficiencies of power generations

the capacity of single wind turbine is increasing and distances of wind farms is expanding from inshore to more than 50 kilometers away. While in most offshore wind farms voltage-source-controlled high-voltage-direct-current technology（VSC-HVDC）is used to integrate into the shore-side power grid

voltage management and reactive power control must be considered in such two aspects as power grid and wind farmsin order to enhance the flexibility for voltage regulation of wind farms and integrated power grids. In this paper

planning methods and control strategies for reactive power in large offshore wind farms with VSC-HVDC technology access to the power grid are studied. By using the proposed reactive power control strategy

voltage quality during the operation can be effectively improved;voltage stability of integrated power grid can be effectively strengthened and possibilities for tripping wind farms caused by voltage fluctuations can be effectively reduced.