Modeling and Nonlinear Dynamic Behavior Analysis of Photovoltaic-Energy Storage DC Microgrid

In the DC microgrid cluster system, due to the large number of converters, there are many operation modes and switching frequencies. The traditional modeling methods are difficult to balance the accuracy of the model and the simplicity of calculation and are not suitable for different switching frequency systems. In view of the above problems, this paper uses simplified discrete time mapping model to model the system. It combines the state space average model with the discrete time mapping model, which greatly improves the simplicity and accuracy of modeling. Taking the photovoltaic-energy storage system as an example, this paper analyzes the nonlinear behavior of the system and predicts the critical control parameters when the Hopf bifurcation occurs in the system. The eigenvalue sensitivity analysis is used to determine the eigenvalue change rate and change trend when the control parameters change, which provides guidance for the selection of parameters in practical applications. Finally, the high precision of the model is verified by simulation, and the applicability and effectiveness of the method in different switching frequency systems are verified by experiments.