Research And Suppression Of High-frequency Interference On Railway Control Signals Cause Of High-order Harmonics In Feeder Cables

With its advantages of high efficiency,safety and convenience,the electrified railway has become an indispensable means of transportation for people's travel and the lifeline of national economic development.However,the quality of power generated by electrified railways has become increasingly strict,and harmonic problems in traction networks are included.Electric locomotives are the main source of harmonics in the traction network,and the high harmonic content generated by electric locomotives will affect the railway signal equipment along the line in various forms,resulting in a series of effects such as unstable operation of the signal equipment and malfunction.Train driving safety issues.Based on the actual engineering case,this paper analyzes the high-frequency interference of the armored feeder cable to the track circuit,analyzes the mechanism of the interference source,the interference path and the corresponding high-frequency interference control measures,and verifies the analysis by simulation analysis.The correctness of the interference analysis and the feasibility of the interference measures.The main results are as follows:Firstly,the working principle of the electric locomotive traction drive system is introduced.The working principle and control strategy of the three-level pulse rectifier used in the CRH2 electric locomotive are described.The harmonic generation mechanism and harmonic mathematical model of the grid side are carried out.Theoretical analysis;establish a three-level pulse rectifier model based on transient current direct control strategy to simulate various operating states of CRH2 electric locomotive,and analyze the magnitude and harmonic distribution of harmonic current of electric locomotive side under various working conditions.Then based on the composition,parameters and principles of each module of ZPW-2000A,mathematical analysis is carried out for each module,and the corresponding four-port model of each module is established to complete the calculation of the four-port matrix;the ZPW-2000A adjustment state and branching are established without interference.The equivalent circuit in the state,and calculate the voltage value of the receiving terminal in two cases;analyze the interference path of the high-frequency interference in the track circuit,set the equivalent harmonic current source,establish the equivalent circuit of the high-frequency interference superimposed voltage,calculate The influence value of the harmonic current source on the voltage of the receiving terminal is discussed,and the threshold value of the relay malfunction caused by the harmonic current source is discussed.The corresponding simulation is established to simulate and analyze the influence of the equivalent harmonic current source on the rail surface voltage and the receiving terminal voltage.In the case,the interference analysis of the harmonic current is obtained in comparison with the interference-free situation.Finally,the method of using LCL filter instead of L filter is proposed and analyzed,and its advantages and disadvantages are analyzed.For the resonance of LCL filter,the virtual damping control of filter capacitor current feedback and the passive damping control based on split capacitor are discussed.The damping control BODE diagram analyzes the suppression ability of the resonance point and the filtering ability of the higher harmonics;designs the LCL filter parameters,sets the control system and related parameters of the two different damping controls;The Matlab/Simulink toolbox uses two different damping controls for the single-phase three-level finisher based on LCL filter to simulate and analyze the two kinds of damping control simulations,and then proposes an application scenario for electric locomotives.The advantages and disadvantages of the two damping controls are analyzed.