Modeling and stability analysis of a cascaded system composed of photovoltaic simulator and photovoltaic inverter

Photovoltaic (PVS) simulator is an important product for debugging the experiments of Photovoltaic products, such as photovoltaic inverters (PVI). Normally, Photovoltaic simulator works as a nonlinear source via cascading photovoltaic inverters. In this case, the whole system may be unstable when the impedance mismatching as the study of Middlebrook. Based on the existing conclusion of impedance of DC-DC converters, the output impedance of PVS which is controlled as single current loop is derived in this paper. Furthermore, the double-loop controlled PVI that is composed by a single-stage topology is studied to analyze its input impedance. The stability of the whole system is analyzed according to the Middlebrook´s stability criterion and the parameters are designed to make the system more stable. Experimental results show that the stability of the system can be guaranteed by proper design.