Conference article

Catenary-free transportation system is in development and has been installed in several countries. Battery train is used as the train which can travel in catenary-free section using power supplied from an onboard storage system such as lithium-ion battery. However, as characteristics of this type of train, an energy consumption of battery train depends on the state of energy of the storage system. Furthermore, battery train needs rapid charging when running the long distance. Hence, energy efficient design of catenary-free transportation system is important. In consideration of these characteristics, in this research, we propose a generation method of the timetable including running time, dwell time and location of charging infrastructure which is the most energy-saving for catenary-free transportation system with battery trains. Firstly, we conduct a running simulation and reveal the relationship among running time, state of charge of the battery and energy consumption. The characteristic is derived as a two-variable function and nonlinear for each variable. Although this optimization problem can be defined as a nonlinear programming problem, we ease to solve this problem using linear approximation to the energy consumption characteristic. Specifically, we use a method of dividing the characteristic defined on the space as curved surfaces into fine lattice shapes and approximating it as a polyhedron composed of minute triangles. In the end, we carried out a simulation in a simple case so that we can show the effect of the proposed method.

battery train, lithium-ion battery, energy efficiency, train scheduling, optimization, MILP