Optimized configuration and economic evaluation of on-board energy storage system for subway vehicles

The on-board supercapacitor energy storage system for subway vehicles is used to absorb vehicles braking energy. Because operating voltage, maximum braking current and discharge depth of supercapacitor have a great influence on its rational configuration, there are theoretical optimum values based on the analysis of vehicle regenerative braking theory, whose mathematical models for the supercapacitor bank power and capacity requirements are established. To meet braking energy recovery, constrained configuration method is based on the power, capacity and discharge depth of the supercapacitor bank. The supercapacitor bank optimization process is given, and then the effect of operating voltage and temperature on the life of supercapacitor is analyzed from the view of economy. Calculation models of initial investment, operation–maintenance cost and economic benefit of the system are given. The simulation results show that the supercapacitor bank based on power, capacity and discharge depth can meet the requirement of braking energy recovery for subway vehicles. Meanwhile, the economic evaluation of the project shows that the project will achieve good social and economic benefits.