Study of output impedance optimization for stationary super-capacitor energy storage applied in urban rail power supply system

The installation of stationary super-capacitor energy storage system (ESS) in urban rail transit can recycle the vehicle braking energy and improve pantograph voltage profile. Firstly this paper analyzes the control strategy and stability of super-capacitor energy storage system and the effect of load power on stability of super-capacitor energy storage system is researched. Then an improved control method is adopted to improve the closed-loop output impedance of super-capacitor energy storage device and the specific reasoning processes are also given. Simulation and experiment results demonstrate that the proposed method is effective.