The grid-connected system of photovoltaic power generation is connected to the grid through the common coupling point. In case of short circuit on the grid side

the grid-connected system will cause such serious accidents as equipment off grid due to voltage leap. After the fault is removed

the risk of overvoltage and over-current on DC side of inverter is increased due to the voltage swell of grid. The virtual impedance is introduced in this paper to change the reference signal of voltage control linkso as to play a role of voltage support during the fault period. The virtual impedance amplitude and impedance ratio are obtained through analyzing the positive and negative sequence voltage and current after symmetrical and asymmetrical short-circuit fault. In view of the transient impact due to voltage swell after the removal of the fault as well as the analysis of variation of the active and reactive power

a kind of reactive current control strategy is proposed to stabilize bus voltage of the grid-connected point. It is verified by Mattab/Simulink simulation and test of above control strategy that the scheme in this paper can make the photovoltaic grid connected system pass through the grid side fault smoothlyand no voltage oscillation phenomena is appeared after removal of the fault.