Choice of the Parameters of an EMI Monitoring System for an AC Traction Network

Abstract

The problem of ensuring the electromagnetic compatibility (EMC) of the traction network with railway signaling lines is of practical interest, since electromagnetic interference (EMI) from the traction network can cause malfunctions in the signaling systems. In order to ensure the EMC of traction current with track circuits, which are widely used as track vacancy sensors in front of a moving train, EMI in rails is periodically monitored in accordance with their maintenance schedule, which makes it possible to detect excessive increases in the level of interference in the rails in a timely manner and prevent possible failures in signaling systems. The problem of developing embedded systems for continuous monitoring of harmonics in the traction network lies in the need to ensure the necessary measurement accuracy of the interference monitoring system for a traction network in accordance with the strict requirements of standards. The correct choice of control system parameters is difficult because the traction current is a nonstationary random process. In addition, the alternating traction current has a large dynamic range of harmonic values, with their proximity to each other and to a powerful fundamental harmonic, as well as the limitations inherent in the discrete Fourier transform, associated with the impossibility of simultaneously improving the accuracy of measurements in the time and frequency domains. This leads to the need for compromises when choosing the parameters of the monitoring system. The work is devoted to the practice of applying the theory of analog-to-digital conversion and the windowed Fourier transform to develop a technique for correctly choosing the parameters of an EMI monitoring system for traction lines.