Study On High-speed Railway Pantograph-catenary Current Collection Quality Under Environmental Wind Load

The rapid expansion of high-speed railway industry has brought a lot of technical challenges to its safe operation.One of them is the deterioration of pantograph-catenary current collection quality,which has been one of factors restricting the improvement of train speed,and affecting the safety of operation.On one hand,due to the long-span and high-flexibility of railway catenary,the effect of environmental wind on the pantograph-catenary interaction is nonignorable.The short-periodic and time-varying fluctuating wind can cause the forcedvibration of catenary,which can lead to the deterioration of current collection quality and aggravate the fatigue.Under extreme conditions,the environmental wind is able to enable a large-amplitude galloping,which causes the operation interruption.On the other hand,the increase of train's speed causes very complex wave propagation behaviour in the catenary,which also affects the pantograph-catenary contact quality.This paper focuses on the studies of wind-induced vibration behaviour of catenary and the wave propagation property.On the basis of a nonlinear FEM catenary model,the buffeting behaviour of catenary is investigated.And its influence on the current collection quality is studied.The active control strategy is proposed to improve the current collection quality under stochastic wind load.As for the galloping behaviour,the mechanism of catenary galloping is revealed.The self-excited force model is established.The wave diffraction and reflection are investigated.The matching between the wave frequency and sensitive frequency is studied.Through the above analyses,the mechanisms of buffeting and galloping,as well as the wave propagation property are investigated.The measures of suppressing the wind-induced vibration and regulating the contact force are proposed.The main works in this paper can be summarized as follows.Firstly,in order to describe the large-amplitude vibration behaviour of catenary caused by wind load,nonlinear cable and truss elements are adopted to establish the catenary model based on nonlinear finite element procedure.By introducing the shape-finding method,the static configuration of catenary is solved,whose validation is verified by comparing the results with existing literatures.By including a pantograph model,the dynamic interaction of pantograph-catenary is performed.Through several numerical examples,the validation of dynamic solution is verified.Secondly,considering the temporal and spatial correlations of stochastic wind,the timehistories of stochastic wind speed are generated.Based on the fluid-induced vibration theory,the aerodynamic forces acting on contact and messenger wires are derived.Considering the irregularity of contact wire cross-section,the computational fluid dynamics is performed to obtain the aerodynamic coefficients of contact wire.Through dynamic simulation,the windinduced vibration response is analysed.The effect of structural parameters on wind-induced amplitude is also investigated.The distribution of contact wire fatigue is studied under stochastic wind field.Then the effect of stochastic wind on pantograph-catenary interaction is studied.The results show that the wind-induced vibration amplitude increases with the increase of wind speed.The more the wind flows in a horizontal direction,the more significant effect on contact force can be observed.The registration and dropper points on contact wire are the most vulnerable points through the analysis of the contact wire fatigue under wind load.The decrease of span length and the increase of tension can effectively improve the anti-wind capability of catenary.Thirdly,active control strategy for pantograph is proposed to improve the contact quality between pantograph and catenary.A multi-body pantograph model is established to evaluate the control performance.Through placing the PD controllers on the upper and lower frames respectively,the control force and control moment are provided to regulate the contact force.The effect of control gains on control effect is investigated.And the controller sensitivity and time-delay are considered to evaluate the control performance.The control performance is evaluated under stochastic wind field.The results show that a positive proportional gain and a negative derivative gain should be included in a PD controller for reducing the fluctuation in pantograph-catenary contact force.The decrease of controller sensitivity and the increase of time-delay can exert negative effect on the control performance.The appropriate controller parameters can be designed with high controller time-delay and low actuator sensitivity.Fourthly,the mechanism of catenary galloping under extreme conditions is revealed.And the nonlinear finite element method is performed to realize the numerical simulation of galloping.Through the computational fluid dynamics,the aerodynamic coefficients of contact wire are calculated with different classes of wear.Based on the Den Hartog theory,the galloping region is determined.Considering the fluid-structure interaction,the numerical simulation method for galloping is proposed.The galloping response is analysed with different tension classes and stochastic wind load.The results show that the extreme wear of contact wire is able to cause the negative aerodynamic damping,which may enable the self-excited vibration of catenary.The upgrade of tension class can effectively decrease the galloping amplitude.The effect of stochastic wind on galloping behaviour can be neglected.Finally,based on the wave propagation analysis theory,the wave propagation model for catenary is established.The reflection and diffracted coefficients at dropper point are analysed with different structural parameters.Considering the Doppler Effect,the matching between the wave propagation frequency and the catenary sensitive frequency is studied.The results of FEM simulation are analysed based on the wave propagation analysis.The results show that the improvement of contact wire tension and the decrease of messenger wire tension can effectively decrease the reflection coefficient as well as improve the diffracted coefficient.The resonance may occur when the wave frequency is consistent to the structural sensitive frequency,which can lead to the deterioration of current collection quality.