Metro Train-Network Integrated Optimization for Traction Power Supply System with Bidirectional Converter Devices

In order to improve the utilization of regenerative braking energy(RBE) generated by braking trains in urban rail transit(URT), bidirectional converter devices(BCDs) are gradually being applied in traction power supply systems(TPSS), which can feed surplus RBE generated from the DC sides of the network to AC grid. Based on its voltage characteristics, this paper utilizes current-vector iterative method to calculate the power flow of DC network. Furthermore, considering the impact of time-varying train loads and BCD parameters design on transmission, utilization and feedback process of electrical energy, this paper proposes a metro train-network integrated optimization model for TPSS with BCDs to optimize train trajectories, timetable and voltage characteristics of BCDs coordinately, which aims to minimize electricity costs. And a two-layer heuristic algorithm (GA-PSO) is designed to solve the problem. In the case study, the optimization method proposed in this paper can reduce electricity costs by 6.96%, the rate of RBE utilized by vehicles has increased by 8.85% compared to the original case without optimization. And the rate of electrical energy savings is 33.69% compared to actual scenario with conventional TPSS.