Increasing Energy Efficiency in Urban Rail Transit by Integrated Speed Profile Optimization and Traveling Time Distribution

High consumption of electric energy in urban railway systems have prompted many researchers to look for strategies of energy saving. Suitable service with high speed and accuracy is what passengers, as the main costumers of these systems, anticipate. In this regard, energy-efficient train operation due to its considering energy saving and punctuality simultaneously, is very important. In this paper, a solution for energy saving is proposed, so that the constraints related to traveling time are met. Meanwhile, the effect of employing variable regenerative energy recovery rate for each inter-station distance was shown in reducing total input energy of network. This work is conducted over a two-stage optimization process. First, considering the net energy of train and inter-station trip time as the objective functions, optimal speed profiles were provided for single train system. Then, by distributing traveling time over the inter-stations and using predetermined optimal speed profiles, the total input energy of the upstream network is minimized. The simulation results, based on actual operating data of line 1 Mashhad urban railway system confirm the effectiveness of proposed method.