Impedance Modeling and Output Impedance Coupling Analysis of Three-Phase Grid-Connected Inverters

The sequence-impedance-based analysis method is an available approach to analyze the interaction effects of grid–connected system, in which the grid-inverter system can be divided into positive-and negative-sequence subsystems. However, when power calculator and power controller are introduced into inverter controller, the positive-and negative-sequence output impedance of the inverter will be coupled. In this paper, the power meter block and the power compensator are analyzed, and the output impedance matrix model of grid-connected inverter is derived. The output impedance model of the grid-connected inverter is verified by the simulation results. Finally, the impedance stability criterion is adopted to analyze the interaction stability of the grid-connected-inverter system.