Study On Hybrid Energy Storagy System Based On Super Capacitor And Battery

Faced with the energy crisis,the development of new energy sources,such as solar photovoltaic power generation,has more and more attracted.Due to the randomness and intermittence of the solar rays,the output power of the photovoltaic power system is fluctuating.In order to suppress the power fluctuation,the energy storage unit is one of the common methods.In this paper,the energy storage system is composed of super capacitor and battery mixed energy storage medium and bidirectional DC/DC converter,based on the small DC micro grid with photovoltaic power generation system,the energy storage system and the load.The role of hybrid energy storage system in suppressing DC bus voltage fluctuation and the energy management strategy of the system are studied.Firstly,based on the working principle of the super capacitor and the lead-acid battery,the mathematical model is established.And then the charging and discharging characteristics are analyzed,and the state of charge of the battery is obtained.Secondly,the bidirectional DC/DC converter circuit and its working principle are analyzed in detail.According to the mode selections,the mathematical model of the bidirectional DC/DC converter is established in the Buck mode and Boost mode.According to the characteristics of hybrid energy storage,,the topological structure of super capacitor and battery are respectively connected with the bidirectional DC/DC converter parallel to the DC bus is selected.According to the functions that need to be realized in this picture,the high and low frequency separation strategy of the hybrid energy storage is made,and the corresponding charging and discharging control strategy and the coordinated energy management strategy are developed.The circuit model of the hybrid energy storage system is built in the PSIM simulation software.The effectiveness of the control method of the super capacitor and battery and the feasibility of the control algorithm is verified.Finally,the software and hardware realization scheme of the system is given.The experimental platform is built based on Infineon XE164FN microcontroller,control algorithm program is compiled by Keil4 software,and the rationality and feasibility of the control strategy are proved by the experimental results.