The string-type photovoltaic grid-connected cluster system using LCL type grid-connected inverter has high-frequency resonance. Aiming at this problem

this paper analyzes the resonance mechanism of the cluster system and proposes a high-frequency resonance suppression method. On the basis of conventional double closed-loop control

this method introduces high-frequency feedback of capacitive current and high-frequency feedforward of common connection point（PCC） voltage. The capacitive current high frequency feedback has a phase lead compensation function

so that the system will not cause high frequency resonance due to the decrease of the phase margin.The PCC voltage high frequency feed forward can increase the active damping of the system and reduce the high frequency resonance peak of the system. The simulation results of Matlab/simulink show that in single

two and three inverter grid-connected systems

compared with the method without resonance suppression

the total harmonic distortion rate of the grid-connected current of the proposed method is reduced by 83.2%

78.7% and 78.5% respectively

and the system′s higher harmonic content is reduced to less than 0.5%

effectively suppressing high-frequency resonance.