Pantograph-catenary System Research Articles

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.

Active pantograph in high-speed railway: Review, challenges, and applications

The pantograph–catenary system (PCS) vibration causes the pantograph–catenary contact force (PCCF) to fluctuate, deteriorating current collection quality and damaging the electrical equipment. The active pantograph is one of the most promising methods for suppressing PCS coupling vibration and improving the current collection quality of high-speed trains. This paper first summarizes the research progress of five critical links in the active pantograph, including PCS modeling, control algorithm, hardware support, and HIL test verification. Then, the impact of the PCS model on numerical simulation accuracy and calculation time, the pros and cons of different control algorithms, and the execution mechanism selection are discussed. Finally, the active pantograph’s future development trend and research direction are prospected, such as model optimization, algorithm design, and signal correction. The analysis results show that establishing the PCS model should consider the representation of system dynamics and calculation efficiency. Control targets need to reflect the current collection quality comprehensively, and the measurement system needs to minimize the effect of locomotive disturbances on the observation results. The actuator structure needs to execute the control commands efficiently and quickly without affecting the operation of the raising mechanism. These factors, together with the real-time control algorithm, determine the practical effectiveness of the active pantograph.

Study on Friction and Wear Properties of Copper-Impregnated Carbon Slide Plate Under Different Humidity Conditions

The pantograph–catenary system is one of the most commonly used power-receiving modes of metro trains. Its friction and wear performances are related to the safety and stability of train operation. In this study, a copper-impregnated carbon slide plate material, widely used in numerous metro lines in China, is considered as the research object. The problem of abnormal wear of slide plates caused by the decrease in relative humidity in the autumn and winter in tunnels is studied. Current-carrying friction and wear tests under humidity conditions of 20%, 30%, and 40% relative humidity (RH) are performed to reveal the mechanism of seasonal abnormal wear of slide plates and provide a reference for the service of pantograph slide plates under low-humidity conditions. The results reveal that relative humidity significantly influences the wear process of slide plates; further, the wear rate decrease with an increase in relative humidity. As observed by laser scanning confocal microscopy, with an increase in the relative humidity, the mechanical wear of the slide surface is weakened, arc erosion is enhanced, and surface roughness is increased. The Raman spectral scan showed that with the increasing humidity, the graphitization of the surface material decreased significantly, and the molecular structure changed greatly. Scanning electron microscopy (SEM) and energy-dispersive spectrometry (EDS) analysis reveal that under high humidity conditions, a relatively complete oxide film forms on the slide plate and plays a role in lubrication and protection.

Effect and behaviors of ambient humidity on the wear of metal-impregnated carbon strip in pantograph-catenary system

The causes of abnormal wear in contact strip of pantograph have been extensively investigated. Initially, based on field data analysis, the wear rate of strip was found to be strongly correlated with ambient humidity. Subsequently, a series tests of the strip was conducted, and the micromorphology was preformed post-tests, which indicated the evolution law of wear rate under different ambient humidity conditions. Finally, through grey relational analysis, it was observed that the degree of correlation between different influencing factors and wear rate at low humidity was greater than that at high humidity. Based on the findings of the aforementioned study, it is concluded that the abnormal wear of strip is caused by a decrease in ambient humidity.

Comparative Investigation Into the Current-Carrying Wear Properties of Two Kinds of Carbon Skateboard/Wire Contact Under Different Conditions

The poor matching performance of a carbon skateboard and contact wire leads to abnormal wear of a rigid pantograph–catenary system. However, an effective response strategy for reducing the frequency of abnormal wear of the arch network has not been achieved. In this article, the friction and wear properties of pure carbon and copper-impregnated carbon skateboards are used to investigate and compare the friction properties under different working conditions. The experimental results show that the contact resistance of the pure carbon skateboard/contact wire increases from 12 mΩ to 45 mΩ with increasing current and shows an overall low friction coefficient. The contact resistance of the copper-impregnated carbon skateboard/contact wire fluctuates in the range of 4 mΩ to 16 mΩ, with a relatively high friction coefficient. A high current density accelerates the electrical wear behavior and temperature increase of the interface of the pure carbon skateboard/contact wire. A matching strategy of carbon skateboard and contact wire is proposed by comparing the friction coefficient, contact resistance, and wear rate.

Structure Improvement and Control Algorithm Optimization-Based Ground Automatic Neutral-Section Passing Method for Train

Passing the neutral section can causes transient impact and speed loss of the train. Therefore, whether the potential danger of the pantograph-catenary system can be eliminated under the condition of full load operation becomes one of the essential factors for the safe and efficient operation of electric locomotives. This paper proposes an advanced method to optimize the structure and control algorithm, according to the drawbacks of existing methods, such as miniature circuit capacity, poor output driving ability, low control accuracy, and slow system response speed. In this method, the pantograph-catenary arc is restrained by controlling the dynamic alternating transfer of instantaneous power. Besides, the voltage pre-modulation algorithm is used to realize flexible voltage switching between different adjacent power supply arms. Compared with the existing methods, this method can provide better system response output capability. And this can effectively suppress transient impact and ensure full load train operation safety. Finally, in terms of transient suppression effect and resistance to external environmental interference, a series of functional verification and horizontal comparison experiments have proved the feasibility, superiority and robustness of this method.

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.

Study of pantograph-catenary system dynamic in crosswind environments

To study the evolution of the pantograph-catenary system dynamic under crosswind environments, this paper examines the effect of crosswind on the quality of the current collection and explores the wind stability of different longitudinal suspension forms of the catenary system. Firstly, the catenary with different longitudinal suspension forms is established based on the absolute node coordinate formulation, and the initial equilibrium configuration are accurately obtained. Secondly, the pantograph model is derived, and the pantograph-catenary system coupling model is established according to the standard EN 50318:2018 and passed the verification. Then, the random wind speed spectrum of the simulated environment is built based on the Davenport spectrum and is validated. Finally, the pantograph-catenary system dynamic behavior under the crosswind environments is simulated. The results show that the crosswind affects the low-frequency vibration part of the pantograph-catenary system, with the increase in wind speed and the standard deviation of contact force, the worse current collection quality. Different longitudinal suspension forms of catenary systems have various wind stability. Semi-inclined and inclined longitudinal suspension forms have better wind stability, and the maximum reduction of contact force standard deviation is 14.05%, which can effectively improve the current collection quality in crosswind environments.

Experimental research on the mechanism of the delamination extension of the carbon strip with heavy electrical current at the speed of 360 km/h

Delamination wear leads to a surge in the wear loss of the carbon strip. It also has a significant influence on the physicochemical properties of the contact pairs in the pantograph-catenary system (over 250 km/h). In this paper, the pure carbon/copper-alloy friction pair was chosen as the research object to study the wear evolution mechanisms and the law of delamination wear extension of the carbon strip, using a ring-on -block wear tester with a design speed of 400 km/h. And the arc discharge energy was calculated to investigate the quantitative relationship between the delamination wear and the arc discharge in the process of the test. The experimental results show that the frictional coefficient increases gradually with the experiment. The frictional coefficient with electric current is much bigger than that without electric current under the same test conditions. Under the intense arcing (when the average single arc discharge energy e > 76J), the delamination wear initially appears on one edge of the strip and gradually extends to the middle of the strip when sliding time t exceeds a certain value, which results in the increase of the wear of the strip and the further enhancement of the arc discharge. The result also indicates that delamination wear and its extension are occurred by the cumulative effect of the heat caused by the long-time strong arc discharge.

Simulation and Verification of Effect of Arc Duration on Arc Temperature Based on COMSOL

The pantograph–catenary arc of urban rail has the characteristic of high temperature, which directly acts on the surface of the pantograph–catenary system, will seriously ablate pantograph and contact line, and affect the flow of the pantograph–catenary system. In this paper, based on MHD, a mathematical model of the arcing of urban rail pantograph–catenary system is established. COMSOL finite element software was used to simulate the arc temperature field of the pantograph–catenary arc. Through the temperature distribution cloud diagram and related images, the relationship between the arc central temperature, the duration, and the gap of the pantograph arc were studied. It is found that the arc temperature increases with the increase in arc duration when the arc gap is fixed. When the arc duration is fixed, the arc center temperature changes inversely with the increase in the arc gap. The feasibility of the simulation model is verified by the pantograph–catenary arc experiment platform. The research conclusion of this paper can provide a certain basis for the research of arc erosion on the surface of the pantograph–catenary system.

Pantograph Catenary Contact Force Regulation Based on Modified Takagi-Sugeno Fuzzy Models

In this paper, a new contact force control technique, based on the modified Takagi-Sugeno model and the parallel distributed compensation concept is developed to suppress vibrations between the pantograph and the catenary by regulating the contact force to a reference value, thereby achieving stable current collection. The proposed method uses simple and standard PID and modified Takagi-Sugeno fuzzy controllers. The two controllers guarantee the designed system's robust stability. Furthermore, based on a simplified pantograph–catenary system model, the comparative simulation results show that variations of the contact force can be almost attenuated. As a result, the system stability is guaranteed, and the performance robustness is verified.

Review on Test Benches Studying Sliding Electrical Contact and Synthesis of Experimental Results

Sliding electrical contacts are commonly used with a slip ring to collect the current in moving system generators, alternators, or electrical motors. These contacts are also found in electrical transports without batteries, which are mostly supplied by means of a pantograph–catenary system. These systems are fraught with numerous issues. Among them, it is worth highlighting wear and heating, which lead to failures and pre-worn materials. Moreover, with the increase in speed and improvements in technologies and materials, new problems emerge. This is the case with the substitution of the classic copper strip with graphite or copper-impregnated graphite. Multiple works that studied sliding electrical contacts have been achieved recently, some by trying to create a model of the system based on experimental results, and others only based on experimental works and measurements. This paper aims to review articles from this last category by making a synthesis of different test benches used and then by opening a discussion based on different results highlighted by scholars. This discussion is divided into five points that constitute the system inputs. These are the environment, material, normal load, sliding speed, and current. Based on this discussion, a conclusion attempts to evaluate topics where results and trends are commonly established by authors and topics where there is a lack of work or some conflicts in the results or trends between different articles. For this last point, some perspectives are given for further experimental works.

Development of surrogate models for evaluating energy transfer quality of high-speed railway pantograph-catenary system using physics-based model and machine learning

High-speed railway pantograph-catenary system is the only energy transfer pathway to drive a train operation. Energy transfer quality deteriorates with the increasing train speed and harsh service environment, thereby quickly and accurately evaluating the energy transfer quality is very important to guarantee the normal operation of a train. In this study, firstly, the physics-based model to simulate the dynamic interaction of pantograph-catenary system is established and validated. Eleven input parameters involve the essential line design and train operation parameters, and the output parameters that are crucially responsible for energy transfer quality are obtained by feature extraction. Secondly, a sampling strategy is employed to construct the input sampling points, based on which the outputs are computed via physics-based model, then combining them the dataset is obtained. Thirdly, five tree-based classification surrogate models are developed and compared to assess the level of energy transfer quality. Finally, eight regression surrogate models are developed in replacing physics-based model to evaluate the essential values of energy transfer quality. It is found that the gradient boosting decision tree (GBDT)-based surrogate model is the optimal classification model and the multi-layer feed-forward deep neural network (MLF-DNN)-based surrogate model for the optimal regression model. The two surrogate models are expected to quickly find the optimal design parameters and improve the operation control of trains of high-speed railway for the purpose of enhancing the energy transfer quality if coupled with optimization procedure.

Deep Reinforcement Learning Based Active Pantograph Control Strategy in High-Speed Railway

The pantograph-catenary system (PCS) is the essential power supply system in the high-speed railway, but its coupling performance is influenced significantly by the rapidly increasing train speed. The actively controlled pantograph is one of the promising technologies to suppress the fluctuation of the pantograph-catenary contact force (PCCF). In this paper, we propose a novel pantograph control strategy based on deep reinforcement learning (DRL) to overcome the complex time-varying characteristic of PCS, which distorts the system identification of the classical control methods. First, a non-linear pantograph-catenary system model is established based on the finite element and multi-body dynamics theory as the simulation environment in DRL. Then, the state space, action space, and reward in DRL are redesigned to train the agent, which is suitable for PCS. Finally, the effectiveness and robustness of our proposed method are verified under various working conditions and parameter disturbances. The experiment results show that our control strategy can reduce the PCCF fluctuation up to 40% and reject parametric perturbation while achieving state-of-the-art performance on the benchmarks.

A Novel Arcing Detection Model of Pantograph–Catenary for High-Speed Train in Complex Scenes

The Pantograph-catenary system is crucial for transferring electrical power from catenary lines to electrified train and the occurrence of arcing could damage railway operations, thus, it is important to detect arcing. Detecting arcing in complex scenes and detecting different size and shape of arcing is still a challenge. To overcome these issues, a robust image-based semantic segmentation model named ArcMSF is proposed for arcing detection of pantograph-catenary, which designs a novel hybrid multi-scale feature fusion model that aggregates Transformer with CNN to realize arcing pixel segmentation. A down-top decoder for combining low-level features with high-level features is designed to achieve multi-scale level arcing feature detecting in complex scenes. Inspired by the arcing image properties that arcing is always the brightest, the global max features and global threshold features are designed to augment the arcing features. Experiments on dataset IVAIS-PCA2021 and comparative experiments are conducted to demonstrate the effectiveness of the ArcMSF, which can achieve 89.13% segmentation accuracy and the fast inference speed of 23.84ms. Moreover, the detection results have a clear depiction of edge details.

Status Analysis and Prevention-treatment Technology Study of Abnormal Wear of Pantograph Catenary System in Urban Rail Transit

Status Analysis and Prevention-treatment Technology Study of Abnormal Wear of Pantograph Catenary System in Urban Rail Transit

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.

A new method for solving arcs of pantograph network based on Newton’s iterative method

It has been verified that the discharge pulse generated by the pantograph-catenary system has the biggest impact on the high-speed EMU as the electromagnetic interference source. But the spectrum obtained from the existing pantograph discharge model does not contain high frequencies and is far from the measurement results. In this paper, a novel scheme based on Newton’s method and finite difference time domain (FDTD) algorithm was presented to solve this problem. Firstly, Newton’s method was utilized to solve the Habedank model, and the dynamic conductance of the arc was obtained. Then, the equivalent distributed parameter circuit model of the traction power supply system was established, which was solved by the FDTD and state variable method to obtain the time-domain waveform of the arc voltage. The significant features of this scheme are that it can realize the synchronous calculations of the arc dynamic conductance and the voltage responses along the catenary. Through this scheme, a stable arc voltage time domain waveform can be obtained, and the arc voltage spectrum is highly consistent with the test results.

Stability Analysis of Fractional-Order Mathieu Equation with Forced Excitation

The advantage of fractional-order derivative has attracted extensive attention in the field of dynamics. In this paper, we investigated the stability of the fractional-order Mathieu equation under forced excitation, which is based on a model of the pantograph–catenary system. First, we obtained the approximate analytical expressions and periodic solutions of the stability boundaries by the multi-scale method and the perturbation method, and the correctness of these results were verified through numerical analysis by Matlab. In addition, by analyzing the stability of the k’T-periodic solutions in the system, we verified the existence of the unstable k’T-resonance lines through numerical simulation, and visually investigated the effect of the system parameters. The results show that forced excitation with a finite period does not change the position of the stability boundaries, but it can affect the expressions of the periodic solutions. Moreover, by analyzing the properties of the resonant lines, we found that when the points with k’T-periodic solutions were perturbed by the same frequency of forced excitation, these points became unstable due to resonance. Finally, we found that both the damping coefficient and the fractional-order parameters in the system have important influences on the stability boundaries and the resonance lines.

LQR Active Control of Fractional-Order Pantograph-Catenary System Based on Feedback Linearization

Fractional-order calculus has exclusive advantages in modeling the viscoelastic components with obvious fractional-order characteristics such as air springs and metal rubbers in the pantograph structure. In this paper, the air spring is tested, and fractional-order calculus is applied to the modeling of pantograph-catenary system of the high-speed train. The parameter identification method of fractional-order derivative is analytically derived. The traditional lumped mass model is improved and a coupling two-degree-of-freedom model of the fractional-order pantograph-catenary system is established. The fractional-order derivative term in the pantograph-catenary model is approximately calculated by the Oustaloup filter algorithm. Taking the time-varying nature into consideration, the catenary is treated as an extended variable to obtain an augmented model. On this basis, the system is linearized based on differential geometry theory, and an LQR controller is designed to control the pantograph-catenary system. The feedback linearized LQR control and PID control are used to control the same type of traditional pantograph, and the results are compared. Meanwhile, the control effects of feedback linearized LQR control under different pantograph parameters and at different train speeds are analyzed. The results show that the feedback linearized LQR control can present a much better control performance than PID control, and the pantograph-catenary contact force and pantograph head vibration amplitude are both reduced obviously. Even at different train speeds or under different pantograph parameters, it can also effectively reduce these control indexes and provide more robust control performance. These results help to put forward new control ideas and theoretical basis for the vibration control of the pantograph-catenary or similar dynamical system.