Energy-Efficient Control Optimization of Subway Train with Bidirectional Converter Substations

The energy consumption of the subway has attracted much attention. Applying bidirectional converter substations (BCS) and researching energy-efficient train control (EETC) strategies can effectively reduce the energy consumption of the subway system. This paper analyzes the coupling model of power supply-train operation with rectifier substations (RS) and BCS. To minimize the energy consumption of substations, an optimal control problem model of EETC is established, and a multi-stage dynamic programming algorithm with state space reduction is designed to solve the train energy-saving speed profile. The EETC results of different line conditions with RS and BCS are presented. The results indicate that the EETC changes with the type of substations, where trains with BCS adopt regenerative braking conditions matched with the inverter turn-on voltage to feed back energy. The relationship between train running time and energy consumption is analyzed, showing that EETC with BCS has superior energy-saving effects and operational efficiency to EETC with RS. Results demonstrate the effectiveness and energy-saving effects of the optimization methods presented in this paper.