Pantograph Catenary Dynamic Interaction Research Articles

Hardware-in-the-loop simulations of a railway pantograph with a finite element periodic catenary model

The pantograph-catenary dynamic interaction problem is addressed by Hardware-in-the-Loop (HIL) tests to simulate the dynamic interaction between a numerical model (the catenary) and a physical device (the pantograph). The real-time simulation requires a computationally efficient numerical model and an on time and accurate transference of the response to the pantograph, for which a Periodic Finite Element Model (PFEM) of the catenary is considered. Firstly because of the acceptable computation time required to solve it, makes it suitable for real-time simulations and, secondly, its ability to allow for the delay caused by the transfer of the numerical model response. The catenary PFEM we used considers the non-linear behaviour of the dropper slackening, leading to highly accurate HIL test results, which were validated up to a frequency of 25 Hz.

Analytical model of the pantograph–catenary dynamic interaction and comparison with numerical simulations

Catenaries are large cable structures which transmit electric current to trains through sliding contact with a pantograph. The finite element method is widely used to model this dynamic interaction problem and obtain the contact force between the pantograph and the catenary. As an alternative, analytical models can also be used to study catenary dynamics, although they require certain simplifications of the features considered in numerical models. In this paper, an analytical model composed of an infinite string and a visco-elastic support is introduced and enhanced by considering a Kelvin-Voigt damping model and the initial height of the contact wire. Considering the finite element (FE) model as a reference, the analytical model parameters are properly adjusted through static and wave propagation analyses to achieve similar behaviour in both the analytical and the FE models. To check the performance of the proposed model, the steady-state response of the pantograph–catenary coupled system is calculated and compared with the results of the FE model. Finally, the analytical model is used to analyse the interference phenomenon produced during two-pantograph operation.

An influence of track stiffness discontinuity on pantograph base vibrations and catenary–pantograph dynamic interaction

Abstract In this article, the computational methodology of the catenary–train–track system vibration analysis is presented and used to estimate the influence of vehicle body vibrations on the pantograph–catenary dynamic interaction. This issue is rarely referred in the literature, although any perturbations appearing at the pantograph–catenary interface are of great importance for high-speed railways. Vehicle body vibrations considered in this article are induced by the passage of train through the track stiffness discontinuity, being a frequent cause of significant dynamic effects. First, the most important assumptions of the computational model are presented, including the general idea of decomposing catenary–train–track dynamic system into two main subsystems and the concept of one-way coupling between them. Then, the pantograph base vibrations calculated for two train speeds (60 m/s, 100 m/s) and two cases of track discontinuity (a sudden increase and a sudden decrease in the stiffness of track substrate) are analyzed. Two cases of the railway vehicle suspension are considered – a typical two-stage suspension and a primary suspension alone. To evaluate catenary–pantograph dynamic interaction, the dynamic uplift of the contact wire at steady arm and the pantograph contact force is computed. It is demonstrated that an efficiency of the two-stage suspension grows with the train speed; hence, such vehicle suspension effectively suppresses strong sudden shocks of vehicle body, appearing while the train passes through the track stiffness discontinuity at a high speed. In a hypothetical case when the one-stage vehicle suspension is used, the pantograph base vibrations may increase the number of contact loss events at the catenary–pantograph interface.

A modal coordinate catenary model for the real-time simulation of the pantograph-catenary dynamic interaction

The computational cost required to simulate the pantograph-catenary dynamic interaction can be a limiting factor in certain applications. Specifically, for Hardware-in-the-Loop (HIL) simulations, real-time capabilities of the software are imperative. In this paper a combination of a modal coordinate approach with an offline/online strategy to build a very efficient simulation strategy is proposed. This novel approach preserves the accuracy of the results, compared with those obtained by classical finite element strategies. Furthermore, a procedure to define and validate a criterion for a priori truncation of the modal basis and an analysis of the effect of explicit treatment of the interaction force are also presented. The results show that the method proposed could be used to perform pantograph HIL tests.

Stochastic Monte Carlo simulations of the pantograph–catenary dynamic interaction to allow for uncertainties introduced during catenary installation

ABSTRACTThe simulation of the pantograph–catenary dynamic interaction is at present mainly based on deterministic approaches. However, any errors made during the catenary stringing process are sources of variability that can affect the dynamic performance of the system. In this paper, we analyse the influence of dropper length, dropper spacing and support height errors on the current collection quality by applying a classic Monte Carlo method to obtain the probability density functions of several output quantities. The effects of installation errors are also studied for a range of train speeds. Finally, the pre-sag that, on average, produces the best behaviour of the system is identified, allowing for the uncertainty in the catenary installation. The results obtained show the convenience to consider variability in pantograph–catenary dynamic simulations.

Analysis of the evolvement of contact wire wear irregularity in railway catenary based on historical data

ABSTRACTThis paper studies the evolvement of the wear irregularity of contact wire using wire thickness data measured yearly from a section of railway catenary. The power spectral density and time–frequency representation based on the wavelet transform are employed for data analysis, with an emphasis on local wear irregularities that are crucial for contact wire condition assessment. To investigate the cause of wear irregularity evolvement and the mutual influence with the pantograph–catenary dynamic interaction, simulations considering the influence of wear irregularity are carried out based on the finite element method. Analyses of the actual wear irregularities and the dynamic contact force under singular and complex wear irregularities are performed. Although the wear irregularity has limited impact on the pantograph–catenary interaction, it can induce the vibration of pantograph and contact wire that will lead to a notable increase of contact force standard deviation. The evolvement of wear irregularity is closely associated with the span length and dropper distribution of catenary structure and the running direction of pantograph. In addition, it is found feasible to detect the wear irregularity based on contact force, on condition that the sampling frequency is high enough to reflect the indicative frequencies.

Fast simulation of the pantograph–catenary dynamic interaction

Simulation of the pantograph–catenary dynamic interaction has now become a useful tool for designing and optimizing the system. In order to perform accurate simulations, including system non-linearities, the Finite Element Method is commonly employed combined with a time integration scheme, even though the computational time required may be longer than with the use of other simpler approaches. In this paper we propose a two-stage methodology (Offline/Online) which notably reduces the computational cost without any loss in accuracy and makes it possible to successfully carry out very efficient optimizations or even Hardware in the Loop simulations with real-time requirements.

An investigation into multi-domain simulation for a pantographcatenary system

There is a need for modelling various phenomena present in a pantograph-catenary structure, (e.g. wave propagation and its reflections, friction, aerodynamic and electromagnetic forces), which allows for a more reliable study on the dynamic behaviours of a railway pantograph, particularly in the case of high-speed trains. Hence, the creation a complex pantograph-catenary multi-domain model should help to effectively meet the above-mentioned requirements. The work presents a co-simulation approach to investigate the pantograph-catenary dynamic interaction. The elaborated co-simulation algorithm assumes data exchange between multibody models of a pantograph and finite element model of a catenary. The presented approach explores multi-domain phenomena that have an influence on the pantograph-catenary interaction. The nonlinear finite element catenary model takes into account the slackening of droppers, relatively large displacements and contact with the pantograph’s slider, while the multibody model of the pantograph considers friction forces and suspension springs. Additionally, aerodynamic forces caused by wind acting on the pantograph were computed using the fluid structure interaction method and implemented in the dynamic simulation. The influence on the pantograph-catenary interaction caused by electromagnetic force acting on the pantograph was investigated, along with the influence of the locomotive’s vertical vibrations and tilt.

Finite element analysis of pantograph-catenary dynamic interaction

Numerical simulations of the pantograph-catenary dynamic interaction allow for assessment of the current collection quality provided by this subsystem at the design stage of the pantograph or the catenary system. In this paper, the authors present numerical results of simulations of the dynamic interaction between a pantograph and a catenary. Adopted catenary and pantograph models are consistent with the reference model presented in the EN 50318:2002 document, which describes the validation procedure of the simulation for the dynamic interaction between pantograph and overhead contact line. Authors have used the Finite Element Method to analyze this complex system. Ten catenary spans of simple catenary (one messenger wire and one contact wire) are modelled, each of them is 60m long. The pre-sag of the catenary is 0mm and the model of the catenary includes the stagger which equals ±200mm. The pantograph model consists of lumped masses which are connected each other with spring-damper elements. First, the static initial configuration is obtained (under gravity and tensioning loads), after which the dynamic transient simulation is conducted. Obtained results for the contact force and uplifts at supports are within the reference ranges presented in the EN 50318:2002 document, therefore it can be considered that the adopted model correctly reproduces the dynamic behaviour of the pantograph-catenary dynamic interaction.

Influence of a high-speed train passing through a tunnel on pantograph aerodynamics and pantograph–catenary interaction

Aerodynamics of trains running inside tunnels change more significantly in comparison with open air scenarios. It has been confirmed that the lateral vibration as well as the aerodynamic drag of the trains is increased and the micro-pressure wave is produced at the tunnel exit when the trains are passing through tunnels. The aim of this article is to explore the impact of a high-speed train passing through a tunnel on the pantograph aerodynamics and the dynamic behavior of the pantograph–catenary interaction. The aerodynamic forces acting on the pantograph are investigated thoroughly by extensive numerical simulations as well as systematic field tests. To investigate the effects of the aerodynamic forces of pantograph on the quality of current collection, the numerical simulations of the pantograph–catenary dynamic interaction are conducted with our proposed model, taking into consideration the action of the aerodynamic uplift forces obtained by the numerical simulations on the pantograph. Then, a series of numerical simulations are also carried out to analyze the effects of the train speed and the blockage ratio on the aerodynamic uplift forces of the pantograph, on the contact forces, as well as on the displacement of the contact wire, while the train is passing through a tunnel. The results reveal that compared with the open air scenarios, the aerodynamic drag and uplift forces of the pantograph, the mean value of the contact force and the displacement level of the registration arm can considerably increase as the train runs inside a tunnel. Moreover, the statistical values of the contact forces and the displacement level of the contact wire become larger while the train is passing through the tunnel at different speeds. On the other hand, the quality of current collection decreases with the increasing of the blockage ratio.

A mathematical model for pantograph-catenary interaction

ABSTRACTModelling the interaction between the pantograph and the catenary is an active field due to the development of high-speed trains. In this article, a 3D mathematical model based on finite element method is proposed to study the dynamic behaviour of the pantograph–catenary system. The equations of motion for a beam element have been discretized to obtain the weak form associated to each element of the catenary. The pantograph–catenary dynamic interaction model is implemented as a numerical simulation tool. The proposed model is compared to the performance of a commercial 3D simulator and it is faced to the requirements of the European Standard EN50318.

PantoCat statement of method

The pantograph–catenary dynamic interaction analysis program (PantoCat) addresses the need for a dynamic analysis code able to analyse models of the complete overhead energy collecting systems that include all mechanical details of the pantographs and the complete topology and structural details of the catenary. PantoCat is a code based on the finite element method, for the catenary, and multibody dynamics methods, for the pantograph, integrated via a co-simulation procedure. A contact model based on a penalty formulation is selected to represent the pantograph–catenary interaction. PantoCat enables models of catenaries with multiple sections, including their overlap, the operation of multiple pantographs and the use of any complex loading of the catenary or pantograph mechanical elements including aerodynamic effects. The models of the pantograph and catenary are fully spatial being simulated in tangential or curved tracks, with or without irregularities and perturbations. User-friendly interfaces facilitate the construction of the models while the post-processing facilities provide all quantities of interest of the system response according to the norms and industrial requirements.

PACDIN statement of methods

PAntograph–Catenary Dynamic Interaction (PACDIN) is a code developed by the vehicle technology research centre (CITV) of the Universitat Politècnica de València in collaboration with the railway company Talgo S.L. The model of the catenary is a finite element model using absolute nodal coordinates. It is based on a general formulation that can be applied for analysing a wide range of catenary configurations, including stitch wire, transitions or non-straight path tracks. The formulation is fully non-linear and includes large deformations, dropper slackening and contact interaction. The model is linearised when deformations are small, as in the case of the benchmark dynamic analysis. The results of the PACDIN code show a good agreement with the average results of other benchmark codes.

Pantograph-catenary Dynamic Interaction for a Overhead Line Supported by Noise Barrier

Subject of the paper is a particular configuration of overhead line, in which noise barrier structure is used as supports of the catenary instead of standard poles. This configuration is foreseen in case the noise barrier position is in conflict with the poles location. If the catenary is supported by the noise barrier, the motion that the latter undergo due to wave pressure associated to train transit is transmitted to the overhead line, so that potentially it influences the interaction between the catenary itself and the pantograph of the passing train. The paper focuses on the influence of such peculiar configuration on the quality of the current collection of high speed pantograph, for single and double current collection. The study has been carried out first with an experimental investigation on the pressure distribution on noise barrier, both in wind tunnel and with in-field tests. Subsequently a numerical analysis of the dynamics of the barrier subjected to the wave pressure due to train transit has been carried out, and the output of such analysis has been used as input data for the simulation of the pantograph-dynamic interaction at different speeds and with front or rear pantograph in operation. Consideration of structural modifications was then highlighted, in order to reduce the influence on the contact loss percentage.

Effect of collector deformable modes in pantograph—catenary dynamic interaction

The aim of the paper is to highlight the influence of the deformable modes of the collector of high-speed pantograph on the quality of current collection. The study was first conducted with an experimental survey on a few collectors for high-speed pantographs, in order to determine their modal parameters and dynamic responses in relation with their structures. Subsequently, a comparison with finite-element modelling was performed, comparing the calculated natural frequencies and mode shapes with the measured ones. Finally, the influence of the deformable modes on the dynamic interaction between pantograph and catenary was analysed, using a simulation model developed in previous works, incorporating the deformable modes of the collector into the model of the pantograph, by means of the experimentally defined modal parameters. The objective of this analysis was to investigate, in particular, the effect of the contact wire irregularity on the contact force up to 100 Hz.

On the use of a hardware in the loop set-up for pantograph dynamics evaluation

The operation of high-speed trains requires higher performance of the pantograph–catenary dynamic interaction, in order to ensure a satisfactory quality of the current collection. Both numerical and experimental approaches are available to assess the dynamic performance of a pantograph coupled with a catenary. In order to reduce the duration of in-line tests, it would be desirable to perform dynamic laboratory tests on the pantograph, that to some extent reproduce the basic features of the real environment. This paper presents a hardware in the loop test-rig, which allows to reproduce the dynamic interaction between pantograph and catenary. In particular, a real pantograph is coupled with a virtual simulated catenary. Using this laboratory set-up, the pantograph dynamics can be evaluated in conditions close to real ones. Some examples of application of the proposed test-rig are also presented.

Pantograph aerodynamic effects on the pantograph–catenary interaction

Some aspects about the influence on the current collection of the aerodynamic action on a pantograph, due to the incoming flow generated by train speed are investigated considering pantograph–catenary dynamic interaction. Starting from the quasi-steady theory formulation of the drag and lift forces on the collectors, and considering the turbulence of the incoming flow, the dynamic variation of the contact force between pantograph and catenary is taken into account, within an already developed simulation model. Aerodynamic coefficients of the collectors are obtained from wind tunnel measurements, and the aerodynamic forces are applied to the collectors of the pantograph. The interrelation among the geometry of the collector suspension, the collector shape, and the level of the incoming wind turbulence, and their effect on the contact force, are all considered in this article by means of numerical simulation. Results concerning the advantage of modifying the shape of the collector are outlined.

Numerical Simulation of Pantograph-Overhead Equipment Interaction

Summary The main features of a mathematical model for the simulation of pantograph-catenary dynamic interaction are presented and, in particular, some aspects related to the catenary and pantograph schematisation are outlined. The model enables to investigate the behaviour of the system in a relatively large frequency range (up to 100 Hz), due to the inclusion of the bending modes of the collector head. In order to simulate the contact between wire and collector, a procedure based on the penalty method is adopted, and it is shown by means of a numerical test case that the method reproduces the constraint acting at the pantograph-catenary interface over a wide frequency range with high accuracy, provided that suitable values are given to the contact parameters. The problem of minimising the numerical disturbances due to the discretisation of the contact wire is also discussed, showing that the entity of these disturbances can be reduced to acceptable values by adopting a proper discretisation of the contact wire, so that no post-filtering of simulation results is required. Applications to some specific aspects of current collection are presented, and comparisons with available experimental data from line tests are shown.

On the prediction of wear of contact wire in OHE lines: a proposed model

SUMMARYThe main features of a procedure for the prediction of the wear of contact wire in overhead equipment for railway traction is presented. The procedure is based on the simulation of pantograph-catenary dynamic interaction, coupled with a wear model of the contact wire. The wear model takes into account, in a first approximation, the electrical and mechanical contribution to wear, generating a worn contact wire profile, introduced as wire irregularity for subsequent simulations. In this way, it is possible to follow the evolution of wear, considering each simulation representative of a given number of pantograph passages.