The overhead contact line is a tensioned cable structure erected along the railroad to power the electric train. Under the wind load, the galloping of OCL caused by aerodynamic instability may form a large amplitude, which is a big potential threat to the normal operation of the electric railway. In this paper, a wind tunnel test is performed to investigate the aerodynamic coefficients of the contact line with two levels of wear. The aerodynamic instability of the contact line can be observed on a worn contact wire at around an 8° wind angle of attack. Employing a nonlinear finite element model of the OCL, the galloping is reproduced and analysed via several numerical simulations. The effect of the wear level and angle of attack on the galloping response is analysed. The galloping amplitude of the contact line spikes at the angle of attack of 8° and 9° at 20% and 30% wear levels, respectively. Then damping dropper is included in the model, and its effect on the suppression of the OCL galloping is quantified. The results indicate that a damping dropper of 100 Ns/m is recommended to be mounted on the railway OCL to reduce the detriment of galloping under a strong wind field.

The pantograph-catenary system is used in modern electrified railways to power electric trains. Common sense is that the increase of train speed leads to a deterioration of the interaction performance. But recent studies indicate that a higher speed may result in a better performance in some local speed regions. This paper is the first attempt to provide a theoretical explanation for this phenomenon. A validated pantograph-catenary model is built to reproduce this phenomenon. Referring the definition of critical speed in moving load problems, the catenary's critical speed is defined. The wavelength components can be extracted through the Fourier transformation to the contact wire's vertical mode shape. The speed that satisfies the resonance condition can be regarded as the potential critical speed. The corresponding contact wire amplitude is further evaluated to determine the critical speeds at a given mode. The analysis indicates that a good interaction performance happens when the speed falls in the transition procedure between the critical two speeds. Based on this idea, a simple indicator that describes the overall contribution of all modes subjected to a moving pantograph at a given speed is proposed to facilitate the determination of the local optimal speed. The variation of the proposed indicator with respect to the speed shows good consistency with the trend of the simulation results. The main finding in this paper can be used in the design phase to determine the optimal speed of the pantograph-catenary system in a local speed range.

In electrified railway systems, the localization performance of catenary support components (CSCs) in service status monitoring systems is crucial for downstream tasks such as anomaly identification and defect detection. However, CSCs detection faces challenges such as multiple categories, multi-scales, and tiny objects, which make it difficult for general object detection algorithms to improve their detection performance effectively. To address these challenges, this paper proposes a novel Anchor-Free Interactive Detector Based on Multi-Receptive Field Mamba (MRFM-IFCOS) to accurately and effectively detect all CSCs. First, a novel lightweight Multi-Receptive Field Mamba (MRFMamba) backbone network is proposed to extract high-frequency edge details and improve feature extraction efficiency by capturing dependencies between long-range regions in images and integrating multi-scale information from different receptive fields, achieving a compelling balance between detection performance and computational efficiency. Then, an Interactive Global Knowledge Distillation (IGKD) strategy is presented to foster more effective knowledge transfer and interaction within student-teacher learning paradigms, enhancing the student network’s feature representation and localization capabilities and reducing computing resource consumption. Finally, a Cross-layer Fusion Feature Pyramid Network (CLF-FPN) is developed to substantially improve multi-level feature fusion and capture fine-grained, high-frequency details crucial for small objects. Experimental results show that the proposed detection framework can achieve a SOTA detection accuracy of 52.52% (mAP) and 19.89% (AP_s) on the CSCs dataset while maintaining low computational complexity.

Overhead conductor rail (OCR) is an important power supply device in tunnel railway lines. The penalty method is widely adopted to model the dynamic interaction behaviour of the pantograph-OCR system (POCRs), while it is difficult to determine a proper contact stiffness value. This paper proposes a three-dimensional contact formulation for the POCRs based on the Lagrange multiplier method. Accurate contact forces can be obtained easily by this contact formulation without the trouble of determining the contact stiffness. Contact force is defined in the global coordinate system as a three-dimensional vector. Coulomb law of friction is adopted in this paper to describe the tangential contact force, and the train speed is included in the contact formulation. The central finite difference approximation method is utilised, and an iteration procedure is elaborated to calculate the accurate contact force vector. The proposed contact formulation is verified by comparing simulation results with in-line measured data. The maximum statistical relative error of the contact force is only 2.63%. The advantages of the proposed contact formulation are also demonstrated by comparing it with the penalty method.

Overhead Conductor Rail (OCR) is a power supply device in tunnel railways. This paper aims to investigate the influence of train speed and support stiffness on the pantograph-OCR system (POCRs) dynamic behaviour, and propose improvement measures to the existing power feeding system to accommodate higher speeds. Firstly, a field test is conducted to measure the equivalent stiffness of the supports currently utilised in the OCR system. The test results are adopted to modify the OCR model. Subsequently, a lumped mass model of the pantograph and the OCR model considering interlocking joints are developed. The analysis reveals that the contact force exhibits a nonlinear variation as the support stiffness increases, and good dynamic interaction can be achieved when support stiffness falls between 10 ⁴ and 10 ⁵ N/m. Then time-frequency analysis explains the origin and amplification factors of multiple frequency components of the contact forces. The results show that structural wavelengths such as span length, half span length and interlocking joint interval are the primary sources of contact force components. Finally, the resonance mechanism of the POCRs is revealed, explaining the occurrence of deteriorated interaction performance under specific support stiffness.

As a common disturbance to the railway pantograph–catenary system, the crosswind usually deteriorates the current collection quality and threats to operational safety. The main topic of this article is to evaluate the effect of crosswind on the interaction performance of pantograph–catenary considering the aerodynamic forces acting on both the pantograph and catenary. The pantograph–catenary system of the Chengdu–Chongqing passenger special line is adopted as the analysis object. The absolute nodal coordinate formulation (ANCF) is employed to model the catenary. The numerical accuracy is validated via the comparison with the field measurement data collected from an inspection vehicle operating at 378 km/h. According to the quasi-steady theory, the wind load acting on the catenary is derived. Computational fluid dynamics (CFD) is employed to calculate the lift and drag forces acting on each component of the pantograph, which are used to derive the equivalent aerodynamic force that can be applied in the lumped-mass model. A special spatial grid is defined for the pantograph–catenary system to generate the fluctuating wind field based on the empirical spectrum. The simulation results indicate that the pantograph–catenary system of Chengdu–Chongqing passenger special railway has an acceptable performance with a crosswind speed of 20 m/s. However, when the crosswind increases up to 30 m/s, some contact force statistics exceed the safety threshold with a turbulence intensity of more than 17%. Through the analysis of the operational safety, it is found that the contact wire always works within the safety range of the pantograph head with a crosswind speed of 30 m/s. However, some safety issues can be seen from the maximum uplift of the pantograph head with a turbulence intensity of more than 21%.