Oscillation Analysis And Suppression Trategies Of DC Traction Power Supply System

With the rapid advance of urbanization construction, and the rapid expansion of the population in the cities, urban road traffic is becoming more and more congested, the construction of urban rail transit has become the preferred way to relieve traffic pressure. But the dense urban rail transport network system and the application of new power electronic devices have brought new problems to the safe and reliable operation of its traction power supply system. Based on the modeling of DC traction power supply systems including metro electric vehicle, the structural stability of the traction power supply system was detailed analyzed, which is of great significance for DC traction power supply system to ensure reliable and stable operation.In this paper, firstly, the characteristics of divergent oscillating current were analyzed in detail, the divergent oscillating current may cause DC traction power supply system feeder protection malfunction, it was compared with the short-circuit current, and a class of non-typical electromagnetic transient process was proposed during subway DC traction power supply system, namely, system oscillation process.Then, each modules composed of the subway DC traction power supply system was detailed analyzed and modeling, the structure and model of metro electric vehicles was deeply analyzed to determine the system oscillate train condition as regenerative braking process, the oscillation-equivalent circuit model of traction power supply system including of electric DC vehicles. The model was transformed to deduce the Differential Equations, by linear process at the equilibrium point, the stability of the system was analyzed by using the Lyapunov indirect method, and the structure of the system oscillation condition was determined. In Beijing Metro Line 1 parameter, for example, the oscillation process of system was simulated.Finally, the effects of changing the system parameters on the stability of the system were discussed, the oscillation suppression strategies were proposed through changing inverter input channels from the perspectives of controlling algorithms and adding equivalent resistance of the DC-link, and the corresponding simulation was done.