High-order Harmonic Suppression Technology And Development Of Device For Distribution System Of Traction Substation

In recent years,the type of AC-DC-AC trains have been widely put into operation and have become the main type of railway transportation.AC-DC-AC locomotives have the advantages of high traction power and high-power factor.And the low-order harmonics which inject the power supply system has been greatly reduced.However,compared with AC-DC locomotives,its high-order harmonics have increased significantly,which have caused many harmonics amplifications and even resonance accidents,and has seriously affected the safety of railway transportation.At present,passive filtering technology is regarded as the most effective means to control high-order harmonics,and there are many successful applications.Nevertheless,the filtering equipment installed in the 25kV power supply system covers a large area and costs a lot,so it encounters some difficulties in application.In order to give priority to the important equipment such as control and protection in traction substation,this paper focuses on the passive filtering technology of 400V AC distribution system in traction substation to solve the harmonics pollution problem of low voltage distribution system in substation.Firstly,this paper makes a thorough investigation and analysis on the high-order harmonics suppression technologies of traction network.Through the study of the source,characteristics and propagation mechanism of high-order harmonics,this paper describes the penetration characteristics of high-order harmonics to low-voltage distribution system of substations.By investigating existing governance schemes of the high-order harmonics,and analyzing its work principles and function characteristics,this paper will use the two-order high pass filter as the harmonics control method of the 400V low voltage distribution system.Then,the technical parameters of the second-order high-pass filter and the heat dissipation system of the device are optimized.Based on the feasibility analysis of the passive filter scheme used in traction substation and the field harmonics test,the basic data of equivalent harmonics impedance,power factor and harmonics voltage content of the domestic electrical equipment are obtained,and on this basis,the key technical parameters of the second-order high-pass filter are designed.In addition,the ANSYS FLUENT simulation software is used to calculate the distribution characteristics of the flow and heat field of the filter device under the conditions of fully enclosed,natural convection and fan installation,and the optimal heat dissipation scheme of the filter device is obtained.Furthermore,the design parameters and filtering effects of the second-order high-pass filters are simulated and verified.A complete simulation model of traction power supply system and low-voltage distribution system is established by using the simulation platform of MATLAB/Simulink.Furthermore,the simulation model validates the validity of the filter parameter design by analyzing its fundamental loss characteristics,harmonics suppression characteristics.Finally,the filter device is developed and assembled,which has been put into operation for harmonics level test.By comparing the measured results with the previous simulation results,the rationality and effectiveness of the second-order high-pass filter technology as harmonics scheme in this paper are verified.