Analysis of Traction System Time-Varying Signals using ESPRIT Subspace Spectrum Estimation Method

Auxiliary static converters in transportation power systems generate non-stationary waveforms, which contain not only characteristic harmonics but also non-characteristic harmonics and interharmonics. Standard tools of harmonic analysis based on the Fourier transform are not suitable for its analysis. Representation of signals in time and frequency domain has been of interest in signal processing areas for many years, especially taking into account time-varying non-stationary signals, which appear in industrial power converters. In this paper, the ESPRIT method is tested for accurate and detail-rich estimation of parameters of currents in the power supply of auxiliary devices in traction systems, also interharmonic frequencies with their changes in time