Detection of Contact Wire Irregularities Using a Quadratic Time–Frequency Representation of the Pantograph–Catenary Contact Force

As for the rapid expansion of high-speed electrified railway industry, the current collection quality of electric locomotives becomes one of the crucial technical issues for the stable operation of trains. The key measurement index that can characterize the quality of current collection is the contact force between the catenary and pantograph on the locomotive roof. One of the major factors that affect the contact force is the contact wire irregularity, which appears to be very difficult to be measured or detected at present. In recent years, the frequency-domain indicators of the pantograph–catenary contact force (PCCF) have been gaining importance to address this issue. In this paper, a recent quadratic time–frequency distribution is selected to describe the time–frequency representation (TFR) of PCCF signal based on its nonstationarity. The Zhao–Atlas–Marks distribution (ZAMD) shows high time–frequency resolution and cross-term suppression for PCCF signals. To investigate the deterioration of the PCCF under contact wire irregularity, a pantograph–catenary interaction model is presented and verified. Some synthetic contact wire irregularities are generated and added to the interaction model. Based on the characteristics of quadratic TFRs of PCCF signals, a detection and localization approach for contact wire irregularity is proposed in this paper. The simulation and real-life experimental results indicate that the different forms of contact wire irregularity could be effectively detected and localized with meter accuracy using the ZAMD.

I. Introduction

In the electrified railway industry, the power for locomotives is continuously transmitted through the contact between the overhead catenary system and the pantograph installed on the locomotive roof. More precisely, the sliding contact between the contact wire of the catenary and the slide plate of the pantograph in a high-speed interaction, which is schematically shown in Fig. 1, ensures the normal operation of electric locomotives. The level of stability and of continuity of the sliding contact determines the quality of current collection for the locomotive [1], which is crucial for all pieces of the on-board electrical equipment, especially for the traction drive system. In general, the major measurement that reflects the quality of current collection is the pantograph–catenary contact force (PCCF). At present, statistical indicators such as mean, standard deviation (SD), and maximum and minimum of the contact force, which are time-domain parameters, are adopted to evaluate the contact quality [2], [3]. The fact is that although these indicators can reveal the trend, fluctuation, and abnormal points of a series of contact forces directly, they tend to become observable after the pantograph–catenary interaction has deteriorated. The anomaly that could be reflected by the time-domain indicators already exists irrespective of whether the measurement is performed or not. In a reasonable way, these indicators certainly can be the proof of certain deterioration, but not the prediction of the deterioration. Fig. 1.

Schematic of the pantograph–catenary sliding contact.