Optimization of Speed Profiles and Time Schedule of the Urban Rail Transit for Energy-Efficient Operation

Abstract

Various optimal control strategies based on dynamic programming (DP) have been devised with the primary objective of energy conservation in the operation of Metro systems. Essentially, the DP algorithms strive to define a speed profile that reduces energy consumption while meeting specific journey distances and targeted travel times, thereby optimizing the operational speed of a train traversing between stations within permissible limits. However, there has been a relative paucity of research dedicated to ascertaining the ideal travel time for each station segment in an optimal manner. In this regard, this study devised a DP methodology with the goal of optimizing both the speed and the travel time for each station section, taking into account a predetermined total running time for a line composed of multiple stations under single train circumstances. To verify its effectiveness, the proposed optimization approach was compared with actual train operational data, encompassing recorded speeds and energy usage. Simulations were carried out mirroring real-world constraints, and the resultant solution adheres to the same speed limitations, distance, and travel time. Additionally, a methodology was introduced to account for any discrepancies between the actual train system and the simulation model. This was validated by comparing the actual energy consumption with the modeled energy consumption for each operational segment, demonstrating a modeling error of less than 1%.

Keywords

• Dynamic programming
• energy efficient operation
• optimal control
• optimization of speed profile
• urban rail transit
• train