Evaluation of Strategies to Reducing Traction Energy Consumption of Metro Systems Using an Optimal Train Control Simulation Model

Abstract

Abstract:Increasing attention is being paid to the energy efficiency in metro systems to reduce the operational cost and to advocate the sustainability of railway systems. Classical research has studied the energy-efficient operational strategy and the energy-efficient system design separately to reduce the traction energy consumption. This paper aims to combine the operational strategies and the system design by analyzing how the infrastructure and vehicle parameters of metro systems influence the operational traction energy consumption. Firstly, a solution approach to the optimal train control model is introduced, which is used to design the Optimal Train Control Simulator(OTCS). Then, based on the OTCS, the performance of some important energy-efficient system design strategies is investigated to reduce the trains' traction energy consumption, including reduction of the train mass, improvement of the kinematic resistance, the design of the energy-saving gradient, increasing the maximum traction and braking forces, introducing regenerative braking and timetable optimization. As for these energy-efficient strategies, the performances are finally evaluated using the OTCS with the practical operational data of the Beijing Yizhuang metro line. The proposed approach gives an example to quantitatively analyze the energy reduction of different strategies in the system design procedure, which may help the decision makers to have an overview of the energy-efficient performances and then to make decisions by balancing the costs and the benefits.

Comprehensive approach to modeling dynamic processes in the system of underground rail electric traction

“…The electric supply system and the electric rolling stock of underground rail system form a complex multi-factor system in which there occur the interdependent transient electromagnetic processes. Studying respective processes contributes to solving optimization problems related to control over rolling stock [3], reducing losses by improving the efficiency of traction equipment [4], enhancing indicators of quality and consumption modes of electrical energy [5]. That makes it possible to develop and improve technologies for onboard and stationary storage devices [6], protection against emergency modes and emergency situations [7] devices that improve electromagnetic compatibility [8], and others.…”

Optimization of Energetic Train Cooperation

“…The force R g (x) = mg p(x) due to the track gradient p(x) depends on the train mass m, the standard gravity g, and changes with the actual train position x along the track. Detailed descriptions of such traction calculations are included, among others, in the works [33][34][35][36].…”

Optimizing the Energy-Efficient Metro Train Timetable and Control Strategy in Off-Peak Hours with Uncertain Passenger Demands

“…The train traction energy consumption is mainly affected by the running time in each segment [43,51]. When a train departs from station i before the departure time of the timetable, there will be more running time for the train to drive in the segment, which will lead to less traction energy consumption.…”

“…In contrast, the energy consumption is evidently linearly increased with the increasing traction mass. Such an increase is accelerated by more traction force or a longer duration of traction applied to achieve the same train speed for a heavier train [43].…”

“…A more realistic model for the dynamic mathematical model of the metro train is formulated in this paper based on the assumption that a train is considered as a belt with uniformly-distributed mass instead of a mass point model [43]. The timetable optimization model formulated in this paper allows trains to drive as the optimal control strategy with a fixed running time of the section contributed by the reduction of dwelling time at the station, which has a significant reduction in energy consumption (more than 20%).…”