Research On Harmonic Resonance And Suppression Measures Of Heavy-Haul Railway Traction Network

With the rapid development of heavy-haul railway in China,overloaded railway transport has become an important way of transporting all kinds of raw materials.Compared with the traction power supply system of general speed railway,heavy-haul railway has the characteristics of large locomotive power and large traction current.Compared with the traction power supply system of high-speed railway,the current heavy load railway has the characteristics of multiple types and quantities of electric locomotives,mixed traction of DC and AC electric locomotives,and concentrated load distribution.These characteristics of heavy-haul railway determine that the harmonic resonance analysis of the traction power supply system of the heavy-haul railway is more complex,and the overvoltage and overcurrent problems caused by harmonic resonance and the power quality problems caused by harmonic resonance are more serious.In order to ensure the power supply reliability of long haul railway traction power supply system,the research on harmonic resonance characteristics and suppression measures of traction power supply system of heavy-haul railway is particularly important.The mathematical model of traction power supply system of heavy-haul railway is firstly established in this paper.Based on the established mathematical model,the generating mechanism of harmonic resonance and the influencing factors of harmonic resonance characteristics of traction power supply system are analyzed.The main influencing factors of resonance characteristics of traction power supply system are obtained as follows: equivalent impedance of system(including equivalent impedance of external power supply and equivalent impedance of traction transformer),traction network length,unit length equivalent impedance of traction network and admittance,etc.Against the hybrid traction operation mode of DC electric locomotive and AC electric locomotive in the traction power supply system of heavy haul railway,the harmonic characteristics of DC electric locomotive represented by SS4 B and AC electric locomotive represented by Shenhua are analyzed respectively,and the harmonic characteristics of some typical heavy-load railway traction substation are analyzed in the measured.The analysis of harmonic resonance characteristics of traction power supply system lays a foundation for the simulation analysis of traction power supply system and provides a basis for the selection of harmonic resonance suppression measures.Considering the actual parameters,a simulation model of a typical overloaded railway traction power supply system is built,and the accuracy of the simulation model is verified by the measured data.On the basis of the established simulation model,the influence of the above factors on the resonance characteristics is analyzed,and it is concluded that the short-circuit capacity of external power supply,the equivalent impedance of traction transformer,and the length of traction network will simultaneously affect the resonance frequency and resonance impedance of traction power supply system.The results show that the position,operating condition,type and quantity of electric locomotive only affect the amplitude of resonance impedance corresponding to resonance point of traction power supply system.In consideration of the harmonic characteristics of the traction power supply system of heavy-haul railway,a hybrid passive filter is proposed,which is composed of a high-pass stopper filter and a double tuned filter,and the parameters of the hybrid passive filter are selected.The simulation results show that the selected hybrid passive filter has both the characteristics of double-tuned filter and stop-wave high-pass filter,which can simultaneously filter low order harmonic and high order harmonic bands of a certain number of times in the traction power supply system,and the filtering rate and filtering efficiency keep a high level.Hybrid passive filter can also effectively suppress harmonic resonance of traction power supply system,eliminate the original resonant points of the system,and improve the impedance frequency characteristics of the system.