Abstract: In order to solve the problem of voltage and frequency fluctuations at the grid-connected point of the

permanent magnet wind turbine during high and low voltage ride-through，a virtual synchronous generator（VSG）was proposed to control the grid-side converter to improve the inertia and damping of the permanent magnet wind  power generation system，so that the voltage and frequency recovery of the grid-connected point could be supported.Through the active power-frequency adjustment function of the VSG，the active power output capacity of the gridside converter was adjusted according to the system frequency variation，and the frequency fluctuation was suppressed under the action of the moment of inertia and damping coefficient. The virtual electromotive force was adjusted by adjusting the reactive power command of the VSG，so that the dynamic reactive power support could be provided for the grid during the voltage ride-through period，and the voltage of the grid-connected point could be adjusted. The continuous fluctuation of system power and frequency was effectively suppressed during the continuous high and low voltage ride-through period，and the grid-connected stability of the system was improved.Finally，the effectiveness of the proposed control strategy was verified by system simulation.

      Key words: permanent magnet wind turbine；virtual synchronous generator（VSG）；high and low voltage ridethrough；frequency fluctuation；continuous high and low voltage ride-through