A Simplified Wide-Bandwidth Generalized Impedance Model for Single-Phase Grid-Connected Inverter in Polar Coordinate System

With the continuous expansion of new energy grid-connected power generation, the utilization of a large number of power electronic inverters results in the aggravating interaction between new energy power generation and the grid, which led to critical wide-bandwidth oscillation. Therefore, this paper proposes a simplified wide-bandwidth generalized impedance model by modeling the single-phase grid-connected inverter in the polar coordinate system. Firstly, the small-signal dynamic model of the inverter in the polar coordinate system based with second-order generalized integrator (SOGI) is obtained. Then a frequency division basis of 10 Hz to 1 kHz is proposed because the dynamic response of each link varies with frequency. Finally, generalized impedance models of the inverter in the different frequency band are established respectively. The good agreement of the simulation result and the theoretical model verifies the feasibility and correctness of the model. The proposed model lays a good foundation for wide-bandwidth modeling of the three-phase system.