Application and control of super capacitor in high-speed railway regenerative braking energy storage

In order to deal with the inefficient utilization of regenerative braking energy generated by high-speed trains during braking process, a regenerative braking energy storage scheme for highspeed railway based on super capacitor (SC) was proposed. In the scheme, railway power conditioner (RPC) was used as the interface circuit to connect the energy storage device with the traction power supply system. The super capacitor, used as the energy storage medium, was connected with the DC link of the railway power conditioner through the bi-directional DC/DC converter, so as to achieve the function of energy storage and compensation of negative sequence current. On the basis of studying the topology of energy storage scheme, the compensation principle of negative sequence current was analyzed, and the control strategy of energy storage scheme was studied according to the compensation principle. In the strategy, hysteresis control method was used for RPC two converters and current closed loop control method was used for bi-directional DC/DC converters in energy storage device. The simulation results show that the proposed storage scheme can effectively recycle the regenerative braking energy generated by high-speed trains and compensate the negative sequence current to improve the power quality of the grid side.