Direct-driven wind turbine generator modular control strategy considering symmetric fault ride-through

The invention discloses a direct-driven wind turbine generator modular control strategy considering symmetric fault ride-through. According to the method, control strategies are provided for a wind turbine, a machine-side converter and a grid-side converter respectively aiming at the phenomenon that a direct-driven fan requires continuous grid connection and reactive support is provided to realize low voltage ride through when symmetrical fault grid-connected point voltage drops. Specifically, firstly, a wind wheel shaft system, a synchronous generator and a machine side/grid side converter part in the direct-driven fan are considered, control links including a phase-locked loop, a current loop, a voltage loop and the like are included, and a 13-order simplified time domain model of the direct-driven fan system is established; secondly, based on the model, an operation mechanism of the wind power generation system is analyzed, and a corresponding control strategy is provided; and finally, analyzing a full-pow