Bifurcation-Based Stability Analysis of Photovoltaic-Battery Hybrid Power System

Photovoltaic-battery hybrid power system (PBHPS) is a good candidate for rural electrification in remote areas. In this system, multiple energy sources are combined together to power the user loads under various system structures. We identify and analyze the bifurcation process when the system enters unstable operation states. Then, a small signal stability criterion is derived for the system based on reasonable simplification of the bifurcation analysis. Furthermore, according to the nonlinear dynamics of the interconnected system with closed-loop control, a large-signal stability criterion is derived with mixed potential theory. The criterion that is straightforward with the dual-loop control can be considered and easily extended to multiple connected converter systems. The criterion is also coincident with the result of bifurcation analysis. Finally, the validity of proposed criteria is verified by simulation and experimental works in a practical PBHPS of 1 kW.