In the large-scale grid-connected photovoltaic(PV)system

the multi-inverter paralleled structure is used to improve the capacity of the system. According to this structure

as PV capacity is increased

the value of grid impedance can be equivalently enlarged with respect to a single PV power generation unit

which will directly result in failure of the control strategy for inverters

and finally a failure of connecting the PV system to grid. Based on the switch averaged model of the grid-connected PV system

this paper analyzes the influence of grid impedance on inverter output current and voltage. Then

by the output current feedback method

the automatic coordination between reference current and actual output current is realized to equivalently eliminate the influence of grid impedance on the stability of grid-connected voltage and the power quality

so as to guarantee the normal operation of system. Finally

the correctness of the theory is verified by the simulation analysis and experiment.