Research On The Resonant Issue In Traction Power Supply System

With the development of electrified railway, the AC-DC-AC electric locomotives are widely used, however, the resonant problems between multiple AC-DC-AC locomotives and the traction power supply system have occurred for many times, which seriously affects the safety of the railway transportation. Aiming at this problem, in this paper, the mathematical model of the vehicle-grid system has been established to analyze the reasons of resonance, finally, resonance suppression strategies have been investigated. A series of studies on the whole vehicle-grid system be carried out.1) It establishes the Thevenin equivalent circuit model of traction power supply system, which contains the detailed model of the line in the railway system, traction power supply transformer and different operation modes of traction power system. Taking HXD2B locomotive as an example, it establishes the mathematical model of the locomotive converter. Then the simulation models of vehicle-grid system is built based on Matlab, which are static and considering the rolling motion of dynamic vehicle-grid system.2) Through the analysis, it is pointed out that the root reason of the low order resonance in the vehicle-grid system is the mismatch between the equivalent impedance of the traction network and the locomotive equivalent resistance which is influenced by the parameters of the locomotive control and hardware parameters. It were analyzed quantitatively by use of impedance ratio criterion, such as electric locomotive inductor and filter capacitor, voltage loop control parameters and current loop control parameters, finally, the effect of times resonance of many software and hardware factors were be found. Contrast suppression measures between lines and locomotive converter side3) For the resonance phenomenon, Contrast all kinds of suppression measures often taken to suppress from the line side and the locomotive converter side, analyzes the mechanism of various methods. A novel resonant suppression strategy is proposed to improve the system damping ratio by increasing the virtual impedance, the simulation results verify the effectiveness of the proposed resonance suppression strategy.4) The semi-physical simulation platform based on dSPACE is set up, the analysis results and suppression methods are verified by experiments.