Low/high Voltage Ride Through (L/HVRT) fault problems seriously affect the safe and stable operation of Permanent Magnet Synchronous Wind Turbine Generator (PMSG). In order to improve the L/HVRT capability, an improved optimization strategy is proposed based on the conventional control scheme, in which the multi-mode operation control scheme is adopted for the normal and fault transient process of the wind turbine respectively, that is, the Maximum Power Point Tracking (MPPT) is realized in the steady state process of the rotor. When the fault is transient, the speed value of the input and output power difference is adjusted, the rotor speed is changed, and the active input value on the side of the machine is suppressed. Based on the degree of voltage swell on DC side, dual-mode unloading resistance switch scheme is proposed to stabilize bus voltage value and voltage fluctuation. The reactive power compensation scheme and Static Reactive Compensator (STATCOM) are put forward on the grid side to provide the maximum reactive support for the power grid. The simulation model is built through the Matlab/Simulink platform to verify the validity and rationality of the proposed scheme. This work is supported by National Natural Science Foundation of China (No. 51675354 and No. 51665052).