Mechanism and Quantitative Analysis of Harmonics for Grid-Connected Inverter During Asymmetrical Grid Fault

Under the condition of asymmetric fault of power grid, the voltage of power grid has negative sequence component, which seriously affects the quality of output voltage and current of grid-connected inverter. Based on the analysis of model and control strategy of grid inverter under asymmetric fault, this paper studied the influence on the output voltage, the output current and the voltage on DC bus made by negative sequence component, revealed the mechanism of grid inverter output current harmonic component and quantitative analysis of each order harmonic, put forward the measurements to restrain the harmonics and voltage fluctuation on DC bus. The effect of negative sequence voltage and the mechanism of harmonic generation are validated by PSCAD simulation and results.