Modeling Of High-speed Railway Vehicle Network Coupling System And Analysis Of Differential-Frequency Oscillation

In this paper,it is found that when the switching frequency of four quadrant rectifier in EMU deviates,it will lead to low frequency oscillation of AC side current,which is not conducive to the operation of EMU.In order to solve this problem,the matrix small signal model of four quadrant rectifier is established,and the reason and law of differential frequency oscillation are analyzed.Firstly,the model of vehicle network coupling system is established,which is composed of all parallel autotransformer traction power supply system and EMU.The principle of traction substation,autotransformer substation and traction network in the system and the establishment of their simulation modules are introduced.The topological structure of traction converter,the working principle and control strategy of four quadrant rectifier in CRH3 EMU are also introduced.The simulation model of vehicle network coupling system is built on MATLAB/Simulink simulation platform,and the difference frequency oscillation phenomenon is simulated by the model.It also introduces the RT-LAB hardware in the loop simulation platform,and uses it to test the effectiveness of the vehicle network coupling system.Secondly,the matrix small signal model of DC-DC converter and AC-DC converter is established.The matrix small signal model of PWM comparator in two kinds of converters is introduced respectively.Then,the converter model is derived by combining with the equivalent structure diagram of the converter,and the model is verified.In addition,the impedance model of DC-DC converter is established.Thirdly,the matrix small signal model of parallel four quadrant rectifier is established and its correctness is verified.In this chapter,the reason of differential frequency oscillation is introduced,and the influence of frequency difference,switch frequency,inductance,current-loop controller parameters on the oscillation is analyzed.Finally,a parallel four quadrant rectifier experimental platform based on NI c RIO-9030 is built.The important hardware and software design of the experimental platform are introduced in detail.Then,the phenomenon of differential frequency oscillation of the parallel four quadrant rectifier is verified by the experimental platform.