LCL active power filter（APF）

as a three order system

is adopted widely in the distribution grid because

it can not only ensure to eliminate high frequency switching components

but also

reduce greatly the value of inductance at the same capacity. However

with the large number of LCL APF parallel access to the distribution network

the problem of its resonance will not be ignored. In view of the interaction problem between the parallel LCL APF and thepower grid in this paper

the equivalent circuit model of the parallel LCL APF system is set up and parallel resonance characteristics analysis of the parallel LCL APF system is performed so to obtain the expression of the parallel resonance. A kind of capacitive damping current feedback active damping strategy instead of the passive damping is proposed to suppress grid resonance in APF parallel system.The effects of different active damping parameters on the suppression of parallel resonance is analyzed further.Finally

the correctness of above theoretical analysis and the effectiveness of the control strategy are verified by the RT-LAB simulation.