Research On The Impact Of SS4 And CRH5 Mixed On Power Quality Of Traction Network

Along with the transformation and upgrading of the existing of electrified railway from Harbin to Dalian,traction load has also become the SS AC-DC type of electric locomotive,HXD AC-DC-AC type of electric locomotive to the series of CRH EMU,there inevitably exist passenger and freight transportation and EMU which is mixed the same line in the existing railway system.Traction load has the characteristics of single phase of nonlinearity,randomness and fluctuation,caused by the voltage fluctuation,harmonics,negative sequence and a series of the power quality of traction network,which will affect the safety and reliability of the power supply system.This paper firstly analyze the working principle of rectified circuit which is unequal three winding and phase-controlled,and derive in detail the calculation process of back EMF and thyristor trigger angle at different levels and at different speeds.The simulation models of SS4 was established by using Matlab/Simulink software,and the harmonic analysis of grid side verified simulation model which is reasonable and effective.Secondly,this paper make a detailed analysis of the CRH5 AC-DC-AC EMU traction drive system of the main circuit structure and working principle,and focus on the transient direct current control of the four-quadrants pulse rectifier,and analyse inverter and traction motor the indirect rotor flux oriented vector control strategy and modulation mode,and build CRH5 simulation model of traction drive system.The running characteristics of locomotive traction condition are simulated,the simulation results show that the parallel duplicated carrier phase-shift technology can reduce the grid side of total current harmonics and improve the grid side of power factor,making better the output voltage waveform and being helpful to optimize the grid side of power quality.Again,four-quadrants pulse rectifier of high and low harmonic generation mechanism is derived theoretically,simulation model of SS4 and CRH5 mixed was established under the same power supply arm,analyzing the changes of traction network current with traction condition and the condition of CRH5 regenerative-braking at stable operation of SS4 and SS4 stable operation of CRH5 under different power,the analysis and summary of mixed running traction power quality.Finally,the section of power quality supply of SS4 and CRH5 measured and analyzed by using UP-2210 online power quality monitor and PQ secure power quality of monitoring and assessment software,the actual measurement results verify the correctness of the theoretical analysis and simulation.At the same time,aiming at the problems of power quality in this kind of mixed running,the concrete improvement measures are given.