Optimal energy management of a DC power traction system in an urban electric railway network with dogleg method

Abstract

ABSTRACT Today, due to the several benefits of using the subway as a clean transportation system and also its expansion in many cities around the world, electrification to urban and suburban railway systems is experiencing a very important development procedure. Optimal power supply and management of energy that is economically viable is one of the important issues in the design of such systems. In this paper, in order to provide an optimal energy management and to determine the location of rectifier substations (RSs), and also to calculate power supply capacity (PSC) of the traction units, an optimal design and simulation of a DC railway traction power supply system (RTPSS) in urban area is proposed. In this regard, first, the structure of power system of RSs used in urban area is presented and analyzed in detail. Then, considering the importance of the standard criteria in designing the dynamics of a city’s RTPSS, an equivalent circuit for the desired network is provided. After defining the governing equations of the network and using the dogleg optimization method, to ensure convergence, the speed of solving equations is improved. In this study, in order to verify the performance of the presented method, the cost-based convergence characteristic curve for Dogleg optimization method is compared to the particle swarm optimization (PSO) approach. In order to confirm the robustness, applicability, and superiority of the proposed approach for optimal design and energy management in a city railway power system, the presented method is applied to a real study case. The obtained results through the simulation approve the effectiveness of using the Dogleg optimization method in power consumption by approximately 255 kWh in reducing energy compared to the practical energy consumption for one train during the trip in normal condition.