Abstract: Aiming at the problems of grid-connected H-bridge photovoltaic inverter grid-connected current distortion and high low-order harmonic content caused by non-ideal grid voltage conditions, the control strategy of energy storage converter of cascaded H-bridge under the condition of non-ideal grid is studied. First, the topology and mathematical model of the three-phase cascaded H-bridge energy storage converter are analyzed and introduced. Secondly, on the basis of quasi-proportional integral-harmonic resonance(PI-HR) regulator, when the grid voltage is unbalanced and harmonic- pollution, the dual current closed-loop control system under the synchronous rotating coordinate system is established, a specific control structure block diagram is given, and considering the stability of the system, the phase margin, amplitude margin, and fundamental frequency gain of the system are taken as the stability constraint conditions, the constraint equations for the controller parameters are established. Finally, a Matlab/Simulink simulation model of three-phase cascaded H-bridge multilevel energy storage converter system is built. Simulation analysis verifies the correctness and effectiveness of the control strategy designed in this paper.