Pantograph-catenary Interaction Research Articles

Active Displacement Control of Pantograph-catenary System for a Half-body Railway Model

The pantograph is an essential component that provides electrical contact between the overhead wires and the electric train. The quality of the current collection in high-speed trains is directly influenced by the mechanical interaction between the pantograph collector head and the overhead contact line. To overcome these challenges and improve pantograph performance, researchers and engineers have explored innovative solutions, including the introduction of active control mechanisms. Excitation by the vehicle is one of the normal disturbances in the dynamic interaction of the pantograph and the overhead line. The vertical effects of vehicle-track vibrations on the interaction between the pantograph and the overhead contact line have not yet been adequately researched. To fill this research gap, this study establishes models for both the pantograph-catenary interaction and the vehicle-track system. In this study, the performance of the modified Skyhook-Proportional-Integral-Derivative (PID) controller was investigated for a half-body of a railway pantograph-catenary system. Track irregularities such as step, sine, and random were applied to perturb the suspension system. The performance of both passive and active systems was investigated by considering the track irregularities as a basis. The root mean square analysis (RMS) found that active displacement control of pantograph-catenary systems for a half-body railway model equipped with modified Skyhook-PID controllers performed better than the passive systems. In summary, the future experimental approach for active half-body railway model could incorporate this simple modification of the Skyhook-PID controller.

A comparative study on the influence of typical track failures on high-speed pantograph-catenary interaction dynamics

Different track failures are proven to have different influences on train-track interactions, but their influence on pantograph-catenary interactions has not been investigated thus far. In this work, the influences of typical track failures on pantograph-catenary interaction dynamics are first investigated. A reduced train-track-pantograph-catenary interaction model is developed to study these effects. In this model, the long catenary is reduced to a small moving area around the moving pantograph, and this area is considered and modelled as the reduced catenary model based on the arbitrary Lagrangian–Eulerian method. The reduced catenary model and moving pantograph are formulated as the reduced pantograph-catenary interaction model, and it is further unidirectionally connected with the existing reduced train-track interaction model to formulate the reduced train-track-pantograph-catenary interaction model. The present reduced pantograph-catenary model is first validated by the EN50318-2018 standard, and the influences of track irregularity, track buckling, fastening failure, and track settlement on pantograph-catenary interaction dynamics are studied. The investigation results first show that the track settlement with a long wavelength has a significant influence on the pantograph-catenary interaction dynamics and can even cause contact loss with a good train-track interaction behaviour. Thus, it should be further mentioned in the maintenance of the track structure.

Pantograph–Catenary Interaction Prediction Model Based on SCSA-RBF Network

As a traditional numerical simulation method for pantograph–catenary interaction research, the pantograph–catenary finite element model cannot be applied to the real-time monitoring of pantograph–catenary contact force, and the computational cost required for the multi-parameter joint optimization of the pantograph–catenary system with the finite element model is very high. In this paper, based on the selective crow search algorithm–radial basis function (SCSA-RBF) network, the time-domain signal of the panhead acceleration, which can be obtained in real-time through non-contact test technology, is taken as the boundary condition to directly solve the pantograph dynamic equation and a data-physics coupling model that can quickly predict the pantograph–catenary interaction is proposed. The prediction model is trained and verified using the dataset generated through the finite element model. Furthermore, the prediction model is applied to the multi-parameter joint optimization of six pantograph dynamic parameters and nine pantograph dynamic parameters, considering nonlinear panhead stiffness, and optimization suggestions under various speeds and filtering frequencies are given.

Assessment of railway pantograph-catenary interaction performance with realistic pantograph strip imperfection

In high-speed rail operations, the pantograph-catenary system is commonly utilised to transmit electricity to the high-speed train. This is achieved through a sliding contact between the pantograph strip and the contact wire of the catenary. The pantograph strip, typically made of softer carbon material, is designed to experience wear, ensuring that the replaceable and cost-effective strip is more likely to deteriorate than the contact wire. However, imperfections in the pantograph strip can adversely affect the interaction performance of the pantograph-catenary system. To quantify the effect of pantograph strip imperfections on the interaction performance, this paper aims to incorporate the measurement data of pantograph strip wear into the numerical simulation of pantograph-catenary interaction. The study collected 58 sets of measurement data on pantograph strip wear from Shanghai Hongqiao station. By employing a well-developed pantograph-catenary model, several numerical simulations were conducted to investigate the dispersion of dynamic behaviours caused by strip wear. The results demonstrate that the inclusion of strip imperfections introduces a certain level of dispersion in the interaction behaviours of the pantograph-catenary system. Specifically, at the operating speed of 300 km/h, strip imperfections can lead to a 16.62% increase in the standard deviation of the contact force and an overall decrease in the minimum contact force. Consequently, it is crucial to update the technical specifications to account for the impact of pantograph strip disturbances. Furthermore, each strip's wear induces a comparable level of dispersion in the contact force standard deviation. However, the contact force on the rear strip typically exhibits greater fluctuation, making it a significant contributor to the overall interaction performance.

Railway catenary optimisation with span variability by an iterative optimisation algorithm for large numbers of parameters

Optimising the catenary topology to improve the pantograph–catenary interaction is computationally expensive. Especially in the case of large numbers of parameters. Unfortunately, varying span lengths and dropper distribution in realistic systems requires the inclusion of a vast number of parameters, making the optimisation problem extremely complicated. Published optimisation works assume that the catenary is a perfectly periodical structure to reduce the number of parameters involved in the optimisation and keep the computational cost below a feasible limit. This paper attempts to deal with the scientific challenge of optimising a realistic system by proposing an iterative optimisation strategy consisting of optimising groups of parameters separately and repeating the optimisations iteratively to consider the dependence between parameters that otherwise would need to be optimised together. This solution performs topological catenary optimisation in catenary zones with span variability or transition zones in which optimisations that assume periodicity are no longer valid.

Dynamic Parameter Optimization of High-Speed Pantograph Based on Swarm Intelligence and Machine Learning

Good pantograph–catenary interaction quality is a fundamental premise for ensuring stable and reliable current collection of high-speed trains, and the optimization of dynamic parameters of high-speed pantographs provides an effective approach to improve the current collection quality of the pantograph–catenary system. In this paper, with the objective of minimizing the standard deviation of the pantograph–catenary contact force, the multi-parameter joint optimization for pantograph at different filtering frequencies and running speeds was carried out by using swarm intelligence optimization algorithm and artificial neural network method. First, the selection operator in genetic algorithm (GA) was introduced into crow search algorithm (CSA), and the selective CSA was proposed, which can effectively improve the solution accuracy and convergence rate of multi-parameter optimization. Second, a radial basis function (RBF) neural network was used to construct a surrogate model of the standard deviation of contact force with respect to the running speed and pantograph dynamic parameters, and a method for optimizing the upper limit of mapping interval of the decision variables by the selective crow search algorithm (SCSA) was proposed, which effectively improves the generalization ability of the surrogate model. Finally, by combining the surrogate model and SCSA, optimization iterations for a total of 630 combined conditions such as cut-off frequency, running speed and pantograph dynamic parameters were conducted, and an optimization method for high-speed pantograph dynamic parameters with universal applicability was proposed.

Effects of Crosswind on Pantograph–Catenary Wear Using Nonlinear Multibody System Dynamic Algorithms

In this study, a multibody system (MBS) computational framework is developed to determine the exact location of the contact point and wear prediction resulting from the pantograph–catenary interaction. The railroad vehicle models in the MBS computational framework comprise rigid-body railroad vehicles, rigid-body pantograph systems, and flexible catenary systems. To avoid incremental rotation, the nonlinear finite element absolute nodal coordinate formulation is used to model a flexible catenary system in the MBS computational framework. To avoid co-simulation processes, the rigid-body railroad vehicle and the pantograph and flexible catenary systems were integrated into the MBS algorithms. The pantograph–catenary interaction is modeled using an elastic contact formulation developed to include the effect of pantograph–catenary separation and sliding contact. The proposed MBS approach evaluates the location of the contact point, contact force, and normal wear rate (NWR) from the mechanical and electrical contributions. This investigation considers the vibration caused by a crosswind scenario and determines the numerical result in the case of a steady crosswind scenario. The steady crosswind scenario contains the advantage of pantograph–catenary aerodynamic design, and the vibration of the catenary system remains significant after the excitation of a steady crosswind. In the case of a steady crosswind, the higher value of the steady crosswind effect significantly increases the mean contact force and the NWR from the mechanical contribution. After crosswind load disturbances, the mean contact force decreases, but the standard deviation of the contact force increases. Therefore, the NWR from the electrical contribution increases significantly. However, the total NWR increases with the crosswind velocity.

Assessment of catenary condition monitoring by means of pantograph head acceleration and Artificial Neural Networks

Measuring the pantograph–catenary interaction force is crucial for homologation and maintenance purposes. However, this is an intricate procedure that requires a specially-instrumented pantograph. As an alternative to the traditional method of measuring the interaction force, we propose in this paper a new procedure to predict the current collection quality (usually quantified by the standard deviation of the interaction force) from the vertical acceleration measurements of the pantograph collector head.The proposed approach consists of properly preprocessing the acceleration signals to train and validate Artificial Neural Networks (ANNs) to predict the standard deviation of the interaction force. First, the proposed method is defined with academic examples in which different ANNs identify dropper defects and severe contact wire wear from numerically generated pantograph accelerations. The normalization of the input data and proper resampling to make samples independent of the train speed are revealed as key aspects in the success of the proposed approach.Also from a numerical point of view, the method is then applied to predict the standard deviation of the contact force. The results obtained show that these predictions have an error of less than a 10%. The analyses of other potential scenarios such as different train operating speed ranges and the use of displacements instead of acceleration as input, show a poor generalization power of the ANNs used. They provide accurate results only when fed with input samples with the same features as those used in the training stage.Finally, the proposed approach is applied to the experimental data obtained from a pantograph lab test bench. In this case, the ANNs are able to predict the current collection quality with less than a 10% error in almost 95% of the cases. This work aimed to be an intermediate step between pure numerical analysis and real data measured on track.

Track and catenary reconstruction from aerial images for the realistic analysis of rail electrification systems

Currently, the modelling of the railway catenaries for straight tracks is well understood and demonstrated via an accepted number of applications and an international benchmark. However, in the presence of a general track geometry, including curved tracks, challenges still remain. The fundamental difficulty is how to address the catenary layout in the presence of curves for a long railway track in which a large number of catenary sections are defined. To support the catenary design, e.g. in new electrification projects, it is fundamental to identify the track geometry, which is not always accessible to the overhead line engineers. This work purposes a novel approach for track geometry reconstruction using aerial views. The reconstruction methodology is based on the general geometry rules for track design. The track geometry obtained is then used as the reference to define the layout of the catenary. The Network Rail Series 1 overhead equipment is used here and the 3D finite element model of the catenary is built on the curved track geometry. The results of this work demonstrate, not only the advances proposed to study more realistically the pantograph-catenary interaction, but also the need to consider general curved tracks in acceptance and interoperability studies.

1D CNN Based Detection and Localisation of Defective Droppers in Railway Catenary

Defective droppers pose a significant threat to the performance of the contact between the train pantograph and railway catenary. In this paper, the impact of damaged droppers on the performance of pantograph–catenary interaction behaviour is analysed, and the impact of varying degrees of damage to each dropper is labelled. To improve the classification accuracy when both the damage degree and position are considered, a model integrating multiple 1D CNNs is proposed. Approaches including randomly searching the optimal hyper-parameters and K-fold cross-validation are used to prevent overfitting and to ensure model performance regardless of the training data subset selected. Compared with a conventional 1D CNN, the classification performance of the integrated method is demonstrated using the metrics accuracy, F1-score, precision and recall. It is concluded that, through the use of the integrated 1D CNN, damaged droppers can be detected and localised based on the pantograph–catenary contact force. Hence, intelligent catenary inspection can be enhanced.

Surrogate modelling of railway pantograph-catenary interaction using deep Long-Short-Term-Memory neural networks

The interaction performance of the pantograph-catenary is of great importance as it directly determines the current collection quality and operational safety of trains. The finite element method (FEM) is dominantly used for simulating pantograph-catenary interaction, which is normally computationally heavy. In this work, addressing the tremendous computational cost of FEM models, a surrogate model for fast simulations of pantograph-catenary interaction is proposed using deep learning. A dataset containing 30,000 cases of pantograph-catenary interaction is generated by a validated FEM model. A Long-Short-Term-Memory (LSTM) neural network is proposed to learn the inherent nonlinearity between the input model parameters and the output pantograph-catenary contact force from data. The resulting prediction performance indicates that contact forces predicted by the surrogate model are consistent with those simulated by FEM, while the computational efforts of the surrogate model are negligible compared with FEM. Prediction performances using different network architectures and configurations are compared to determine the optimal setting for a pantograph-catenary system. The LSTM-based surrogate model shows high efficiency for simulating pantograph-catenary interactions and promising practicability in optimising catenary structural parameters for design or upgrade.

A study on the optimal spatial damping distribution in railway pantograph-catenary interaction

Railway overhead contact lines are very low-damped structures with a high modal density in the low-frequency region. This has a significant impact on the interaction with the pantograph, especially in the high-speed case and in multiple pantographs operations. This paper studies the optimal spatial damping distribution in overhead contact lines obtained by introducing localised damping connections, resulting in a non-proportional damping distribution. To this end, the simulation software Cateway is presented and adopted in conjunction with evolutionary multi-objective optimisers to seek for the most efficient spatial damping distribution. The study is conducted on a high-speed reference model considering two different train speeds. The final goal of this optimisation is to obtain useful hints about the most and least sensitive regions to damping modifications. A dedicated study on the locus of the poles of the system is also proposed to corroborate the findings of the analysis. Results show that significant improvements on the current collection quality can be achieved by carefully designing the spatial damping distribution, especially for the rear (trailing) pantograph. On the other hand, wrong design choices can lead to a degradation of the contact forces.

Effect of Ambient Temperature on Current Collection Quality in Pantograph–Catenary Interaction

This paper investigates the effect of the ambient temperature change on the dynamic interaction between pantograph and catenary (PAC). Thermal expansion/contraction of the components of the overhead contact system (OCS) is considered. Simulation results show that the thermal stress has a much greater influence on the longitudinal positioning of the contact wire than on the horizontal and vertical positioning. When ambient temperature reduces to [Formula: see text] from design temperature of [Formula: see text]C, the maximum longitudinal displacement of the positioner can reach as high as 301 mm, while the maximum horizontal and vertical displacement of the positioner is within 4[Formula: see text]mm. The change of ambient temperature results in the uneven tension distribution of the contact wire, especially near the central anchor. With the increase in temperature, the tension of contact wire decreases; vice versa, with the decrease in temperature, the tension of contact wire increases. For nine-span OCS, the tension change caused by ambient temperature change shall not exceed 2%. The variation of ambient temperature also leads to the deterioration of current collection quality. It is shown that a decreasing ambient temperature results in more significant changes in contact force, close to 5%. An increasing ambient temperature environment leads to a higher uplift of pantograph, close to 30%.

Hardware-in-the-Loop Test Bench for Simulation of Catenary-Pantograph Interaction (CPI) with Linear Camera Measurement.

Catenary-pantograph contact force is generally used for assessment of the current collection quality. A good current collection quality not only increases catenary lifetime but also keeps a stable electric supply and helps to avoid accidents. Low contact forces lead to electric arcs that degrade the catenary, and high contact forces generate excessive wear on the sliding surfaces. Railway track operators require track tests to ensure that catenary-pantograph force remains between safe values. However, a direct measure of the contact force requires an instrumented pantograph which is generally costly and complicated. This paper presents a test bench that allows testing virtual catenaries over real pantographs. Therefore, the contact point force behavior can be tested before the track test to guarantee that the test is passed. Moreover, due to its flexibility, the system can be used for model identification and validation, catenary testing, or contact loss simulation. The test bench also explores using computer vision as an additional sensor for each application. Results show that the system has high precision and flexibility in the available tests.

Review of Perspectives on Pantograph-Catenary Interaction Research for High-Speed Railways Operating at 400 km/h and Above

Review of Perspectives on Pantograph-Catenary Interaction Research for High-Speed Railways Operating at 400 km/h and Above

Railway pantograph-catenary interaction performance in an overlap section: Modelling, validation and analysis

The overlap section is a railway catenary arrangement where the pantograph transfers from one section to another. In the overlap section, the unsynchronised vibration of two contact wires, contact wire height variation, and elasticity unevenness destabilise the pantograph-interaction performance. This paper presents a systematic investigation of the dynamic behaviours of the pantograph-catenary in an overlap section, including the mathematical modeling, model validation and numerical analysis. In combination with the traditional shape-finding method, an initialization procedure is proposed to accurately describe the crossing point height in an overlap section of a catenary. The measurement data of the maximum uplift of the crossing point collected from the field test in the Gardemobanen line is utilised to validate the pantograph-catenary model in the overlap section. The numerical analysis mainly focuses on the effect of the crossing point height and the inclusion of steady arm damping on the interaction performance at different speeds. The results indicate a strong dependence of the dynamic behaviour in an overlap section on the train speed. A good performance can be achieved with a low crossing point when the speed is much lower than the design speed, while a high crossing point can benefit the transition distance and maximum contact force at high speed. The inclusion of a steady arm damper can improve the pantographs' performance at a low speed. However, the effectiveness degrades with the increase of the train speed, especially for the leading pantograph.

Design optimisation of railway pantograph-catenary systems with multiple objectives

Both the mean contact force difference and the standard deviation of the contact force were minimised in the presented optimised design of a pantograph–catenary system for the purposes of improving of the current collection quality and the reduction of the contact wear. The non-dominated sorting genetic algorithm-II (NSGA-II) was applied to optimise the pantograph–catenary interaction system. The adopted NSGA-II algorithm was improved by avoiding repetition of FEM simulations with the duplicated input parameters and retaining only one of the duplicated results for the next generation selection. Either the catenary or the pantograph can be optimised individually by using the proposed versatile approach. In this research, the design optimisation of the catenary system was conducted first. After that, the pantograph was further optimised based on the optimised design of the catenary system. A case study indicated that the standard deviation of the contact force was reduced by 33.4% in the optimised catenary design and 39% in the optimised pantograph design, and the contact force differences were reduced by 98.3% and 99.9% in the optimised catenary design and the optimised pantograph design, respectively. Highlights Both the standard deviation of the contact force and the difference between the actual mean contact force and the ideal mean contact force are minimised in the optimisation design of a pantograph–catenary system. Either the catenary or the pantograph can be optimised separately by using the proposed versatile approach. Non-dominated Sorting Genetic Algorithm-II (NSGA-II) was improved by avoiding repetition of finite element method simulations with the same input parameter combinations and retaining only one of the same results for the next generation selection. A case study indicates that the standard deviation of the contact force can be reduced by 33.4% in the optimised catenary design and 39% in the optimised pantograph design, and the contact force difference can be reduced by 98.3% and 99.9% in the optimised catenary design and the optimised pantograph design, respectively.

Assessment of pantograph-catenary interaction in a railway overlap section via a novel optical-based method

• Pantograph-catenary interactions at an existing overlap span are investigated. • A novel optical-based method is proposed and implemented at the overlap span. • Single- and double-pantograph train passages are obtained and studied. • Dynamic effects rendering high contact forces, contact loss and arcing are studied. • Peak contact force, transition distance and train speed show a strong correlation. Smooth pantograph-catenary contact is essential for regular train operation. However, catenary section overlaps are locations where peak contact forces occur, which significantly affects current collection quality. This work studies pantograph-catenary interaction and transition at an existing overlap span by using a novel optical-based measuring method. Image sequences of eleven single- and two double-pantograph train passages were processed to obtain wire displacement responses. The unsynchronised vibration of two contact wires was found, and the first contact wire exhibits different modal responses. The spatial motion paths of contact wires were obtained to estimate the pantograph-catenary interaction. Dynamic effects rendering high contact forces, contact loss and arcing were investigated. The results show that pantographs with a long transition distance and a high intersection gradient cause a serve impulse with the second contact wire, resulting in contact loss and arcing. Finally, this study successfully estimated the transition distance and found it has a strong positive correlation with peak contact forces and train speeds. The transition distance exhibits an increasing tendency with increasing train speed. The longer transition distance results in a higher peak contact force.

An improved full Fourier series method approaching the stitched catenary in high-speed railway

ABSTRACT The railway catenary is the typical tensioned beam structure arranged along the railway lines, supplying power to the moving high-speed trains. The accurate static form-finding and dynamic behaviour prediction of the structure are the fundamental problems. An improved full Fourier series (IFFS) method is proposed to describe the mechanical behaviour of the stitched catenary. Different from the conventional Fourier series method, both the sin and cos series are adopted, and the proportional and constant terms are added. The initialization process and the static characteristics of the stitched catenary are given and compared to the finite element method (FEM). The effects of the expanding orders are discussed, considering the calculation efficiency and accuracy. The differences caused by the stitch wire are analysed, consisting of the static state and the dynamic performance in pantograph–catenary interaction, supporting the structural design of the high-speed railway catenary.

A Study on the Vibration Characteristics and Damage Mechanism of Pantograph Strips in a Railway Electrification System

This paper presents the vibration characteristics of a pantograph–catenary interaction in a rigid catenary system. Both computational simulation and laboratory tests are carried out to evaluate the frequency contents of pantograph strips. Based on the observation that irregular wear is characterized by the consistency between the pantograph strips’ wear pattern and the mode shape of their dominant modal frequencies, it is deducted that resonance occurs at the pantograph strip and the contact wire interface in the high frequency range. By applying damping treatment to the pantograph strip, and hence improving its damping property, a reduction of 7 dB in the total vibration level at the sliding contact can be achieved, as verified through field tests. It is also found that the worse the initial condition of the pantograph–catenary system, the more prominent the damping effects on the control of high-frequency vibration for irregular wear problems.