A Train Scheduling for Energy Optimization: Tehran Metro System as a Case Study

Energy efficiency is one of the main issues in designing and operating different electrical systems. Energy-saving in electrical railway systems is an important concern due to the high amount of used energy. In order to find optimum energy consumption, different methodologies shall be examined. In addition, various affecting factors should be determined, and suitable solutions should be adopted. This paper illustrates that proper train scheduling is one of the effective approaches to optimize the system energy. Accordingly, comprehensive modeling is proposed considering different affecting factors such as the slope of different lines, the speed limits in each section, the time limit between the arrivals of trains to each station, and different modes of operation such as motoring and braking. Using the proposed model, an optimization problem with the objective function of energy-saving is solved. To evaluate the effectiveness of the proposed method, the proposed scheduling scheme is applied to Line 2 of Tehran Urban & Suburban Railway Operation Company. Based on the results, using the proposed scheme causes a 3.2% energy-saving compared to the existing train movement schedule in the same line. The proposed train movement scheduling program is proceeding to the last verification steps and will be used as a part of Tehran Metro navigation system in the near future.