Resonance analysis and suppression of system with multiple grid-connected inverters

The resonances of grid-connected system with multiple inverters would enlarge harmonics which bring challenges to the performance of inverters and power quality of the grid. The impedance model of the system is established and the resonant mechanism and characteristics is analyzed. From the analysis result, a global resonance suppression strategy based on virtual admittance is proposed which only reshapes the grid impedance around the resonance point, and it has little influence on fundamental wave control. The capacity of the harmonic suppression unit is decreased while the suppression effect is assured. The simulation results verified the correctness of theoretical analysis and the effectiveness of the proposed method.