Device for realizing low voltage ride-through capability of wind turbine generator system

The invention discloses a device for realizing low voltage ride-through capability of a wind turbine generator system, which is characterized by comprising a voltage-4-quadrant converter, a DC side capacitor, a bi-directional DC converter and a super capacitor bank, wherein the voltage-4-quadrant converter is cascaded with the bi-directional DC/DC converter. The device is connected to a common connection point of a wind power station; when the wind speed change causes the fluctuation of the output power of the wind power station, the super capacitor bank outputs or absorbs certain active power through the voltage converter so as to level the fluctuation of the power; and when the failure of a power network causes voltage drop, the power of the wind power station output to the power network is reduced, the mechanical power input to the wind power station is basically unchanged, the super capacitor bank is controlled to absorb certain active power, and a series of problems of DC link capacitor charging, DC voltage quick rise, motor rotor acceleration, electromagnetic torque sudden change and the like caused by inner digestion of excess power are avoided.