Supercapacitor Storage Design and Optimal Control of it for Energy Saving in Urban Rail Transit System

In this paper, an energy storage system is proposed for saving regenerative braking energy based on supercapacitor. This storage system includes a supercapacitor and two bidirectional half-bridge DC-DC converters. Since the metro network includes a forward path and a backward path, by using this proposed storage system it is possible to exchange energy between forward and backward lines. Also, it is affordable in terms of operating costs and reduction of losses because of using one storage devices for both paths. Therefore, the main purpose of this paper is designing storage system and also determination of its control parameters using Particle Swarm Optimization (PSO) algorithm with the objective of energy saving in metro network. Simulations has been done in MATLAB / Simulink software and based on actual data of Mashhad urban railway. The simulation has been done in two modes, with and without energy storage system. Some operational parameters including bus voltage and currents of substations have been obtained in these two modes. Comparison of simulation results shows the effectiveness of the proposed method.