A Comparative Study of Technologies for Wayside Energy Storage in DC Rail Transportation Systems

In this work, a battery energy storage system (BESS), a supercapacitor energy storage system (SCESS), and a hybrid of BESS-SCESS (HESS), have been investigated for application in DC rail transportation. These storage technologies recuperate regenerative braking energy from the trains, which facilitates energy saving and peak power reduction of the substations that power the transit system. The sizes of these technologies have been determined by following a two step process, in which the first step comprises development of detailed mathematical model that is optimized to reduce the total investment cost corresponding to certain percentage of energy saving. In the second step, the sizes obtained from mathematical modeling, are simulated by developing a comprehensive simulation model of the transit system, ESS and ESS management system (EMS) in MATLAB/Simulink. The mathematical model provides initial sizes in a large search space, while the dynamic simulation highlights practical system limitations that impose bounds on the cost-effective recovery of regenerative braking energy.