Research On High Order-Harmonic Resonance Frequency Of Traction Network

In recent years, with a large number of operation model in AC-DC-AC electric locomotive and EMU. the old AC-DC electric locomotive rectifier are gradually being phased out. In the traction power supply system, although low harmonic content is greatly reduced, but new orthogonal transmission locomotives and EMUs in the converter switching frequency in the vicinity of the higher order characteristic harmonic content is obviously increased, and caused by the traction network harmonic resonance case increased, the normal operation of the railway to produce a threat.Therefore, in order to grasp the characteristics and laws of the harmonic resonance frequency of traction network, the main work is summarized as follows.Firstly, in order to grasp the impedance frequency characteristic of traction power supply system, the harmonic impedance of traction power supply system needs to be modeled accurately and completely. Based on the theory of parallel multi conductor transmission line, combined with the characteristics of the network topology of traction power supply system, a unified chain network model is established for traction network with different power supply modes, and introduce the calculation method of the line series impedance and shunt capacitance, as well as post-merger wire matrix equivalent degree reduction.Mathematical model of traction substation. briefly discuss the mathematical model of an external power supply. Then focus on the mathematical model and calculation methods of different impedance of traction transformer. According to the simplified circuit model, this paper describes the mechanism of the resonance, draw a few inferences provides a research idea for the later simulation analysis.Using MATLAB/Simulink software, based on the traction power supply system from the power supply, traction transformer and the traction network line to the load are simulated and modeled. M language programming and GUIDE image interface tools are used to complete the parameter input interface, which solves the problem of the large number of parameters caused by different structure and different components in the simulation.Based on the simulation platform, according to the characteristics of traction power supply system structure and parameters, respectively, to study load location, supply arm length, traction power supply, traction transformer, second order damped filter factors on the effect of harmonic resonance frequency characteristic of the traction. Summarize and analyze the rules of the change in resonant frequency of each influence factors, then According to the reasonable value range of the parameters in the traction power supply system, the approximate range of the resonance frequency of the traction network is given by the simulation.Finally, the paper introduces the high order harmonic resonance case of HXD1B locomotive in the XiangTang to Jiujiang West power supply section.which was measured under Nanchang Railway Administration. According to the measured data, the influence of different distances on harmonic resonance and the change of resonance point of traction network under different power supply are analyzed. The influence of load position and length of power supply arm on the resonant frequency is verified.