Vibration Characteristics And Wave Propagation Law Of Pantograph-Catenary System In High-speed Railways

The sliding contact between the pantograph and the catenary is the only power supply for the electrified locomotive.However,due to the high flexibility and the complex operation environment of the system,there exists the complicated wave propagation in the catenary.And the wave propagation plays an important role in affecting the contact quality with pantographs.In this paper,a series of analyses are carried out to investigate the wave propagation mechanism in the pantograph-catenary system(PCs),including the study of the PCs modeling procedure,the analysis of the wave propagation in the catenary and the non-contact measurement method of catenary dynamic uplift.Besides the theoretical studies,the single contact wire(CW)test and the full-scale catenary test are designed to furtherly investigate the wave propagation and reflection.The main contributions of the paper can be listed in the followings.Firstly,a finite element model(FEM)of the PCs is developed based on the nonlinear cable and truss elements to describe the large-amplitude behavior of the system.And being different from the traditional segregated method,the nonlinear integration procedure is adopted into the model to simulate the continuous change of the PC interaction more precisely in every integral step.In order to verify the PCs model and the proposed segregated method,several numerical examples are given to be compared with the related standard and some published literature.Secondly,the transmission coefficient of the catenary is derived,which is defined as the wave component transmitting from the CW to the messenger wire(MW)via the dropper.Then the PCs model is utilized to analyze the influences of the wave propagation parameters on the current collection.The results indicate that,the raito of the locomotive speed versus the wave speed has a magic influence on the abnormal value of the contact force.And both the decrease of the reflection coefficient and the increase of the transmission coefficient lead to the amount of the abnormal value decreasing.Thirdly,the vibration tests of the single CW with lumped masses attached are designed,which are aimed to investigate the wave reflection caused by the the waveguide-discontinuity of the catenary.It is told by the test results that,the reflection coefficient caused by the mass discontinuity increases with the tension increasing.And the higher-frequency wave components are more sensitive to the tension change.It is also suggested by the results that the dropper mass has negligible influence on the wave reflection,which indicates that the wave transmission supported by the dropper deserves the more attention.Fourthly,in order to obtain the dynamic uplift of the catenary more accurately,the non-contact measurement method based on the neural network algorithm is proposed to address acquisition errors caused by the noisy background.The proposed method is proved effective on the catenary uplift extraction considering the different illumination conditions.Finally,the full-scale catenary tests are carried out to study the actual wave propagation and reflection occurring in the catenary.An analytical method considering the back-and-forth reflections between the adjacent droppers and the wave transmission between the CW and the MW is proposed to identify wave components in the tests.The full-scale catenary test suggests that,the wave reflection occurring in the catenary is the combined effect of the wave transmission and the waveguide-discontinuty reflection caused by the dropper.And the measured data can be decomposed into wave components with different reflection order,in which the higher-reflection-order component has the fewer energy to be kept within.In conclusion,this paper is focused on the research of wave propagation characteristics in the high-speed catenary,including the pantograph-catenary modeling approach,the catenary uplift measurement method and the wave reflection occurring on the catenary lines.The results in the paper are beneficial to the further investigate of the pantograph-catenary dynamics and design.