Transient arcing often occurs as an electric locomotive traverses an electrical sectioning overlap (ESO), deteriorating current collection stability and reducing the durability of the pantograph–catenary (PC) system. In this study, the formation mechanism and electrical evolution characteristics of transient arcing in the ESO region are investigated through theoretical analysis and numerical simulations. First, based on the dynamic motion of the locomotive passing through the ESO, the transient arcing mechanism of the ESO is clarified, and the plasma characteristics of the arc are described. Then, the electromagnetic, airflow, and thermal field interactions within the PC contact gap during arc ignition are analyzed. A Multiphysics coupled PC arc model is developed, incorporating aerodynamic, electromagnetic, and heat transfer effects. Subsequently, finite element meshing and boundary conditions are applied to simulate the transient evolution of the ESO arc. Finally, the transient arcing characteristics of the ESO are analyzed. The results indicate that the current density is highly concentrated at the initial arcing stage and gradually forms an axially symmetric conductive channel (approximately 107 A/m2), which shifts upward as the contact gap increases. Moreover, due to the geometric discontinuity of the ESO, a strong localized electric field develops near the wire edge, leading to arc root migration and reignition.

The catenary system is the power source of high-speed trains and it contains critical components such as droppers and messenger wires. During train operation, the messenger wire vibrates in conjunction with the catenary. In order to obtain a more realistic vibration performance of the droppers, it is necessary to consider the vibration of the messenger wire. In this paper, the vibration equation of the messenger wire is first derived and solved, and the obtained solution is used as the boundary condition of the differential equation of the vibration of the dropper. By solving the differential equation of the dropper using the numerical method, the stress time diagrams of the dropper with and without considering the messenger wire are obtained. The results show that the maximum stresses of droppers I, II, III, IV, and V with the messenger wire are, respectively, 173, 154, 170, 222, and 164MPa; however, those without the messenger wire exceed 300, 500, 400, 500, and 300MPa. It can be seen that the maximum stress value of the dropper becomes lower after considering the effects of the messenger wire. It indicates that the messenger wire can attenuate the degree of vibration of the droppers, thus improving the overall vibration performance of the droppers.

Infrared thermography techniques have proven to be very effective for assessing the fatigue limits of metallic materials with obvious temperature variations. But for some materials, it has been shown that the temperature variation is very limited, and the accuracy of infrared thermographic techniques is not verified. In this study, the fatigue properties of a high-strength steel (SAE52100) were evaluated with traditional fatigue-loading techniques and infrared thermographic methods. The traditional fatigue experiments were loaded at a frequency of 80 Hz with a stress ratio of R = -1, and the fatigue limit at the fatigue lifetime of N = 107 cycles was about 800 MPa. Besides, three additional specimens were loaded with step-by-step increasing stress-loading amplitude, where the maximum temperature increments and temperature distribution were recorded via infrared thermographic techniques. The infrared detections revealed that the maximum value of the temperature increase was only about 1 °C. The fatigue limit was first evaluated based on the maximum temperature variation, then the prediction was refined based on fatigue intrinsic dissipation. The fatigue limits predicted with maximum temperature variation were shown to be 841 MPa, 772 MPa, and 787 MPa, respectively, while the fatigue limits predicted based on fatigue intrinsic dissipation were 793 MPa, 791 MPa, and 789 MPa. Finally, an FEM simulation of temperature variation during fatigue loading was implemented to verify the experimental results. This study provides a solid foundation for the applications of infrared thermography techniques for materials with lower energy dissipations.

In this paper, numerical computation of dropper stress and fatigue life in a catenary system under fluctuating wind load is performed. We take contact wire as a beam element and obtain the response equation under the action of moving load and fluctuating wind load. Thus, we determine the initial boundary value conditions of the vibration equation of the dropper and calculate dropper stress and fatigue life under different conditions. The results show that when contact wire is subjected to fluctuating wind load with a constant wind attack angle, the higher the wind speed, the more serious the fatigue damage caused by fluctuating wind to the dropper. When the wind speed is constant, the smaller the wind attack angle is, the smaller the adverse effects of fluctuating wind on the dropper are. Under the fluctuating wind, fixed wind attack angle and wind speed, the higher the amplitude of the sinusoidal force is, the more likely the dropper is to break, and dropper IV is more sensitive to the amplitude increase. Under the conditions of different wind speeds, attack angles, and amplitudes, dropper IV is most likely to break. This work is helpful to analyze the train safety problems caused by droppers, so as to reduce the safety risks.

The dropper load directly influences the fatigue mechanism of the high-speed catenary system. A proper dropper model for a pantograph–catenary system can be used to accurately and efficiently investigate this phenomenon. In this work, the influence of different dropper models in pantograph–catenary systems on dropper load simulations is investigated. Based on the Euler beam element, a finite element model-based pantograph–catenary system is formulated, and beam, rod, and spring dropper models are considered in this model. After the validation of the present model, the influence of different dropper models on dropper loads and pantograph–catenary interaction dynamics is studied. The calculation efficiency of different dropper models is also analyzed. Based on the investigation results, different dropper models can accurately simulate the pantograph–catenary interaction dynamics, but the spring model is not as accurate as the beam and rod models for dropper loads, and the calculation time of the beam model is much longer than that of other models. Therefore, the use of a rod dropper model in a pantograph–catenary system is suggested for dropper dynamic analysis.

The electrified railways in mountainous areas are faced with multiple difficulties such as weak power grids, special climatic environments, complex, and dangerous geographical conditions, which poses a great challenge to the reliable power supply of the traction power supply system (TPSS). In order to ensure that the overall reliability level of the TPSS meets the design requirements, this paper proposes a reliability allocation method for the TPSS of electrified railways in mountainous areas. Firstly, based on the characteristics of the interconnected power supply system of traction substation group (TSG) of the electrified railways in mountainous areas, the special topology of the TPSS, as well as the logical relationships between each power supply area and each equipment are sorted out. Secondly, the reliability allocation model of the interconnected power supply system of the TSG is established, and the reliability index of the system is allocated layer-by-layer from the whole system to the TSG according to the design requirements of the overall reliability level of the system. Finally, the reliability allocation model of the traction substation is established, and the reliability index is allocated to the underlying equipment of the traction substation, so as to clarify the reliability requirements of each power supply area and equipment. The results indicate that the reliability allocation results calculated by the proposed method can assist designers to be informed of the reliability objectives of each subsystem and power supply equipment, and can provide insights for related reliability design.

The frequent occurrence of the pantograph–catenary (PC) arc seriously threatens the safe and stable operation of electric multiple units (EMUs). In order to investigate the primary factors affecting the electrical characteristics of the PC arc, this paper first reveals the mechanism of arc generation when EMUs leave the split-zone insulator according to the actual mechanical structure of the PC articulated split-zone insulator. Then, based on the Habedank black box arc model, considering the dynamic changes in arc length during the actual operation of EMUs, a numerical simulation model suitable for describing the PC articulated split-zone insulator arc is established. Furthermore, by comparing with existing research results, the effectiveness of the proposed model is verified. Next, a series of simulation experiments were conducted to analyze the influence of different operating parameters of the EMUs on the electrical characteristics of the PC arc. More importantly, the paper proposes using the entropy weight method to calculate the impact strength of different operating parameters of the EMUs on the arc duration time of the contact wire split-zone region. The research results of this paper can provide some technical references for reducing the erosion of the PC contact wire and slide caused by arcs when the EMUs pass through the split-zone insulator.

Steady device is an important component in a catenary for a high-speed railway. It plays an important role in ensuring the current collection quality and stable and reliable operation of the train. In this paper, the strain distributions of positioner tube, column and pin sleeve in the positioning device are measured by strain gauges in our laboratory, and the variation laws of axial and transverse strains, and axial stresses of the three key components under different horizontal and oblique loads, and lifting heights of positioner are studied and analyzed. It is found that the strains and axial stresses of all measuring points basically have a linear relationship with the horizontal load, which are little affected by the oblique load. There is an 'arch' change law between these strains/stresses and the lifting height of positioner. For the stresses of two measuring points at the same section, the tensile stress is generally higher than the compressive stress. The maximum tensile stress occurs on positioner tube, which is the weakest part. This work provides the technical support for the material selection, structural design and detection of the positioning device.

The continuous movement of high-speed train results in the pantograph interacting with a long catenary structure. The traditional methods based on the Lagrangian description can only model the whole long catenary structure, which decreases their calculation efficiency. In this work, a reduced pantograph–catenary interaction model is developed to accurately and efficiently simulate the pantograph-catenary interaction with the long catenary structure. In the model, the long catenary is reduced to a small region around the moving pantograph, and the arbitrary Lagrangian‒Eulerian (ALE) method and modal superposition method (MSM) are used to model this small area. The pantograph is modeled as a multi-rigid body system. The pantograph and reduced catenary model formulate the reduced pantograph–catenary interaction model. Because the long catenary structure is reduced to a small moving region, the number of degrees of freedom (DOF) of the model is significantly decreased. The present model is validated by the EN 50318:2018 standard with a long catenary structure considered. The calculation results show that the present model is accurate and efficient in the investigation of long-term pantograph-catenary interaction dynamics.

Wheel flat can seriously affect the wheel–rail contact performance and cause impact vibrations, which significantly threaten the safe operation of railway vehicles. It is crucial to accurately assess the effects of wheel flats on the wheel–rail contact performance and the vibration impact on the traction drive system. However, studies related to wheel flats have focused on the mechanical part and have yet to fully consider the electrical and mechanical parts of the entire traction drive system. Therefore, this paper first builds an electromechanical coupling model based on the electric traction drive system and the locomotive-track coupling dynamics model. Then, based on this model, the impact of the wheel flat on the electrical and mechanical parts of the traction drive system under different flat lengths, different flat depths, and different vehicle speeds was analyzed. The results indicate that with the increasing depth of the flat spot, the wheel–rail dynamic response, motor rotor speed, and motor torque exhibit more significant fluctuations. Additionally, as the locomotive speed increases, the impact of the flat on the wheel–rail contact performance intensifies. Wheel flats can excite the 1st bending mode of the wheelset, resulting in vibration shocks at 90 Hz.

The off-line discharge between the pantograph and catenary (PAC) occurs frequently in the actual operation of an electric locomotive, which affects the quality of the received current and the service life of the pantograph. The current experiments on the off-line discharge between the PAC are mainly low-power ones and the models established are static. To study the electrical behaviors during the PAC relative motion under the actual working conditions, in this paper, the voltage and current of the contact wire (CW) during its motion are measured. And the electrical behaviors during the rise, fall and reciprocating motions of the pantograph are investigated by combining a finite element method (FEM) model based on the magnetohydrodynamics with the auto transformer (AT) traction network circuit and moving mesh method. It is found that the harmonic frequencies are mainly in the range of 0-30 MHz. The voltage distortion is more obvious during the fall of the pantograph. And the negative polarity spike pulse has a larger amplitude and occurs more frequently. The novelty of this paper lies in the experimental test with the high current and high power, as well as the systematic analysis of the electrical behaviors and multi-physical field evolution during the motion of the pantograph under the working conditions. Its contribution is to present an effective method to study the dynamic behaviors of the PAC. The research results can provide an important reference for the identification of the electrical characteristics of the PAC and the protection of the PAC equipment.

The effective vibration area includes most of the catenary vibration caused by pantograph–catenary interactions and is the basis of the real-time catenary model for hardware-in-the-loop simulation. However, while the length of the effective vibration area is one of the most important parameters of the real-time catenary model, it has not been fully studied at present. In this paper, the length of the effective vibration area is first investigated. A pantograph–catenary interaction model is developed based on the modal superposition method. After the validation of the model, the vibration energy distribution of the catenary is used to determine the length of the effective vibration area based on the converged total energy. The influence of vehicle velocity and contact wire tension on the vibration energy distribution and length of the effective vibration area is investigated. The obtained appropriate length of effective vibration area is validated by a real-time catenary model and online measurement data of the contact force. The investigation results show that the energy distribution of the catenary can accurately determine the length of effective vibration area, and it increases with increasing vehicle velocity but decreases with increasing contact wire tension. The appropriate length of effective vibration area should be at least 160 m (approximately three spans) in the pantograph–catenary system.

Dropper failure seriously threatens the operation safety of a high-speed railway. In this work, for a simple chain suspension catenary, one span with five droppers is performed to establish a model and thus the effects of the moving load speed on dropper stress are investigated. First, the partial differential vibration equation of dropper is obtained through the mechanical analysis and converted into the finite difference equation. Then, we consider contact line as a beam element to obtain its motion equation. Furthermore, the boundary and initial conditions of five droppers are determined. Finally, the stresses of five droppers are numerically calculated and the effects of the moving load speed on dropper stress are investigated by writing a MATLAB code. The results suggest that the dropper location significantly affects its stress. Compared with other droppers, droppers II and IV have much more severe vibration amplitudes. Different moving load speeds could cause different stress change of each dropper. With the increasing speed, dropper experiences longer bending compression stage and the bending amplitude increases. The impact of the moving load speed on dropper stress is significant.

As a key component, the performance of pantograph slide plate is directly related to the normal operation of train and the stability of power supply. The pantograph slide plate is exposed to the complex environment and thus it would face mechanical impacts. In this paper, two types of slide plate models (wide and narrow) are constructed to explore the mechanical behavior of pantograph slide plate under impact using the finite element method. The results show that the slide plates rapidly deform at the beginning of the impact, and then the stress variation speed gradually slows down and tends towards a stable and low amplitude of self vibration. Under strong impact, the vibration frequency and amplitude of the slide plate significantly increase. The stress level of wide slide plate is lower than that of narrow slide plate. Narrow slide plate exhibits higher sensitivity and instability. This indicates that when the train is running at a high speed, factors such as track irregularities and airflow disturbances have a more significant impact on the narrow slide plate. This work provides valuable references for subsequent optimization design.

There is a pronounced coupling vibration between the catenary and pantograph during operation for high-speed railways. In this paper, a pantograph–catenary coupling vibration model is constructed to investigate the vibration characteristics under various working conditions. Two different types of catenaries (simple and elastic chain types) are simulated and compared using the finite element method. The pantograph is simplified into a mass–spring–damping combination member, the contact and messenger wires are set to linear beam cells, and the dropper and stitch wire are set to truss cells. The results suggest that the vibration characteristics of the two types of catenaries and pantograph exhibit different trends. The maximum stresses of the messenger wire, dropper, and contact wire do not follow a monotonically increasing trend with the train speed. The maximum stress of the messenger wire under the simple chain type of catenary is higher when the initial contact force increases from 80 to 120 N. However, the maximum stress under the elastic chain type of catenary is higher when the initial contact force is 60 or 140 N. Except for the initial contact force of 140 N, the maximum stresses of the dropper and contact wire under the simple chain type of catenary are lower than those under the elastic chain type. This work provides a valuable reference for optimizing the design of pantograph–catenary systems.

With the increase in the speed of locomotives, the offline discharge between the pantograph and catenary (PAC) occurs occasionally, which generates the electromagnetic disturbance. The main purpose of this article is to study the electrical behaviors of the offline discharge between the contact wire (CW) with a high current and the pantograph under their relatively high-speed motion, including the characteristics of the discharge voltage, current, and electromagnetic disturbance. By analyzing the experimental data measured by advanced high-power PAC equipment, two discharge forms were found macroscopically. Under different supply currents and speeds, the time and frequency domain characteristics of the discharge voltage, current, and surrounding electric field (EF) were obtained. The main factors causing electromagnetic disturbance were discussed. Then, from the perspective of the migration-diffusion motion of the particle, the main reasons for the pulsation of the discharge current during the PAC offline were explained. Depending on the frequency distribution of the measured results, a 3-D model was built for the research on the PAC offline electromagnetic disturbance. Also, the variation laws of the electromagnetic field in the near and far-field were got. The research results of this article provide the references for the electromagnetic protection of the railway wireless equipment.

The dropper through bends and bears dynamic impact load before and after the train passes in actual service, which has an important impact on the fatigue life of the dropper. In this paper, a simulation model which can simulate the interaction between pantograph and catenary is established by using the numerical simulation method. A dropper model which can simulate the dynamic stress of the dropper is established through the beam-link combination element. The simulation result shows that among the six droppers in a span, the dynamic force of No. 1 and No. 6 droppers is the smallest, and the dynamic force of No. 3 and No. 4 droppers is the largest. The dynamic load variation characteristics of the dropper are characterized by the dynamic coefficient. When the front and rear pantograph pass through, the maximum dynamic force of the dropper appears when the rear pantograph passes through. The maximum dynamic force is located in the middle of the dropper. Through the research of this paper, the simulation method of catenary and dropper is established, and the dynamic stress process of dropper is analyzed, which lays a technical foundation for the subsequent research on the fatigue failure mechanism of dropper.

In this paper, the influence of wind load on the stress characteristics of dropper for a high-speed railway is studied. The section method is used to obtain the vibration equation of the dropper, and the finite difference method is used to convert the partial differential equation of the dropper vibration into a finite difference equation. Through the force analysis of the contact line section upwind, the vibration equation of the contact line with air damping is obtained. Thus, the partial differential equation of the motion can determine the initial and boundary conditions of each dropper. The MATLAB program is written to obtain the stress change diagram of each dropper, and the influence of wind load on the stress characteristics of the dropper is analyzed. The results show that the maximum tensile and compressive stresses of each dropper are different due to the difference of wind load and dropper location, and the dropper in the middle location is most sensitive to the change of wind load. At a low wind speed, there are immediate rebound and obvious attenuation vibration stages during the stress change of dropper. In addition, with the increasing speed of wind load, the stress amplitude and the maximum tensile stress of dropper do not almost change or decrease except the middle dropper.

Dropper is the key component of in a catenary system and it is prone to fatigue fracture. Dropper stress directly affects the operation safety of high-speed railway. In this paper, a span of dropper in a catenary system is modeled to investigate the effects of contact wire tension on dropper stress. The response equation of contact wire and the theoretical equation of dropper stress are deduced. The initial and boundary conditions of each dropper are determined, and then the stress of each dropper is calculated by the finite difference method using a MATLAB program. The results show that the stress amplitude and the maximum tensile stress of the dropper decrease significantly with the increase of contact wire tension. When the tension is low, the stress changes of dropper near the load location experience three stages: instant rebound, attenuated vibration, and bending compression. However, the attenuation vibration stage disappears when the tension is increased to a certain extent. Therefore, the control of the vibration response of the contact wire can effectively reduce the stress amplitude and the maximum tensile stress of the dropper, so as to improve the working reliability of the dropper.

推导吊弦的振动方程,用数值方法求解振动方程,模拟位移,横截面作用力和弯矩的动态变化规律.根据吊弦的应力时程、利用MATLAB数值计算程序分析影响吊弦疲劳寿命的因素(如振幅和频率).数值计算结果表明:吊弦疲劳寿命的对数值随着频率和振幅的增加呈现出线性降低的趋势.