Site and Characteristic Optimization of Retrofitted Bidirectional Converters in Subway Traction Substations Considering Integrated Cost

The rectifier traction substations used in subway power supply systems cannot feed back regenerative energy (RE), leading to high energy consumption. The subway power supply system is retrofitted to effectively feed back and utilize RE based on bidirectional converters (BC) to achieve real-time energy sharing in traction substations. This study conducted a collaborative optimization of the site and characteristics of adding BC to subway substations, reaching the lowest economic cost for the subway system. First, a power flow calculation platform compatible with different types and parameters of substations is established to calculate the parameters of the subway power supply and train operation processes. Then, a minimum-cost objective optimization model is designed, which comprises the equipment and power consumption costs associated with adding BC. A dual-population fusion algorithm based on the red-billed blue magpie optimizer algorithm and rime algorithm is proposed to obtain BCs’ optimal site and characteristics scheme. Finally, the effectiveness of the model is verified through a detailed case study, showing that the comprehensive cost can be reduced by 22.32% compared to traditional rectifier traction substations, and the voltage fluctuation of the overhead contact line is effectively suppressed, ensuring the economical and reliable operation of the subway power supply system.