Pantograph-catenary systems are the key equipment for current conduction from power grids to electric locomotives, and within such a system, the property of the slide, especially the contact resistance ( R_j ), directly affects its current collection performance. Compared to previous studies, this paper focuses on the microscopic roughness parameters which affects R_j greatly. The changing rule of R_j under different roughness conditions is studied on 128 groups of data collected from experiments. More importantly, the second-order partial correlation coefficient is introduced to quantify the impact strength of different roughness parameters on R_j . Based on this, a multi-parameter influence model of R_j is established and verified by non-linear fitting. The results show that the impact strength of the relevant roughness parameters is ranked as R_pc > R_p > R_sm . The conclusion provides a theoretical basis for minimizing pantograph-catenary R_j and improving current collection quality. Moreover, it facilitates slide material selection and contributes to new prototype design.

In the pantograph-catenary system, the change of the surface roughness of pantograph sliding plate directly affects the current collection quality of electric locomotive. In this paper, a large number of current-carrying friction experiments have been carried out on the self-developed high-performance sliding electric contact experimental machine, and the effects of the surface roughness of the sliding friction pair on important performance parameters have been studied, including pantograph-catenary contact resistance ( $R_{j}$ ), current carrying efficiency ( $\eta$ ), current collection stability ( $\delta$ ) and the friction coefficient ( $\mu $ ). Further, the current conduction mechanism is revealed by the microscopic approach. In order to quantitatively reveal the effect of roughness on each evaluation index of current collecting performance, the paper formulates the functional relationship between $R_{a}$ (arithmetic mean height of contour) and $R_{j}$ , $\eta $ , $\delta $ , $\mu $ by nonlinear fitting. On this basis, a comprehensive evaluation equation is established by the entropy weight method, and then the optimal $R_{a}$ value is derived for the best pantograph-catenary current collecting performance. The experimental results show that with the increase of the surface roughness $R_{a}$ of the sliding plate, $R_{j}$ decreases first and then increases, while $\eta $ increases first and then decreases, $\delta $ increases monotonically, and $\mu $ gradually increases. The optimal pantograph-catenary current collection condition can be achieved by reconciliation of these indices. The research results of this paper provide a theoretical basis for improving the current collection quality of pantograph-catenary systems, and is useful for material selection or new type design of pantograph sliding plates.

The dynamic interaction between the pantograph and the overhead conductor rail (PC) system directly affects the current collection stability of electric locomotives. Distinct from previous work centered on transient arcing behaviour, this paper investigates the phase-change-induced melting and ablation characteristics of the rigid contact wire during a single complete PC dynamic separation process. Firstly, a multiphysics-coupled model of the PC offline arc is developed that accounts for energy transfer mechanisms during the transient arcing process, including Joule heating, thermal conduction and radiation. Subsequently, a phase-change melting model of the contact wire is established by incorporating the latent heat effects induced when the contact wire surface temperature reaches its melting point. Then, based on the dynamic simulation model, the obtained separation trajectory of the PC contact pair is applied to the numerical model to conduct a series of transient arcing simulations. Finally, the phase-change melting characteristics of the contact wire and their evolution are revealed under varying separation distances, current intensities and crosswind conditions. The results indicate that a larger separation distance leads to a greater liquid-phase area in the contact wire. Unlike the initial liquefaction time, the liquid-phase area is positively correlated with the current and negatively correlated with the crosswind speed. Additionally, compared to the PC separation process, transient arcing during the PC re-contact process induces a more pronounced thermal accumulation effect.

As many Electric Multiple Units (EMUs) integrate into the traction network, low-frequency oscillation issues may occur in railway systems. Impedance-based frequency-domain stability analysis is a common method used to analyze the stability of vehicle-grid systems. However, the vehicle-grid system is a complex single-phase system with numerous nonlinear components, making it difficult to establish accurate and online-analyzable impedance models. To address these challenges, this paper proposes the Residue Feedforward Neural Network (ResFNN) suitable for EMU impedance identification. The ResFNN integrates residual connections into the deep Feedforward Neural Network (FNN), which can improve the model prediction accuracy and get rid of the complex model derivation process. To explain the contribution of the input parameter to the model, the SHapley Additive exPlanation (SHAP) method is adopted in this paper. Further, according to the above contributions, the paper proposes an unequal step size data collection method to optimize the operating point parameter step size and obtain a small but high-quality dataset. Then, combined with the vehicle-side and grid-side impedance models, this paper can realize online vehicle-grid system stability analysis. Finally, actual case studies are conducted with multiple vehicles connected to the vehicle grid system to validate the feasibility and accuracy of online stability analysis.

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.