The “Plug and Play” Parallel Operation Strategy for the Converter-Based Traction Substations

Based on the research in the previous article, this paper focuses on the parallel operation among the multiple substations. Aming at the particularity of traction power supply systems where the resistance component can not be ignored, we improve the traditional droop control model, and consider the influence of resistance component. Combining with the topology of the traction substation, we propose the control scheme for the parallel operation among ac-dc-ac traction substations based on the impedance characteristics of traction network. A simulation model composed of three ac-dc traction substations is established and verified under no-load and load conditions. The results show that the system can achieve “plug and play” for the power supply and load, and distribute load flow automatically. The system shows good dynamic performance, and exists no impact current in the process of parallel operation. In addition, it can improve the traction network voltage level, and shows nice current sharing performance at the output side of the substation.