Frequency Control Strategy of Grid-Forming Direct-Drive Wind Farms Transmitted Through the HC-HVDC System

With the continuous rise of wind power grid-connected capacity, more and more desert areas will be developed and constructed as new resource bases for wind power in the future. Since this type of wind power base is similar to the island energy network, there is no planning of synchronous generators such as thermal power and hydropower, therefore, the grid-forming control mode is generally adopted. In this paper, a topology of Hybrid Cascaded High Voltage Direct Current (HC-HVDC) transmission system for grid-forming direct-drive wind farms without synchronous power support is constructed. Further, a frequency control strategy for the wind power grid-connected system is proposed. Finally, based on the PSCAD/EMTDC, the electromagnetic transient simulation of the proposed control strategy is carried out to verify its effectiveness.