Modern Spectral Analysis of Non-stationary Signals in Electrical Power Systems

– A novel approach to harmonic and interharmonic analysis, based on the “subspace” methods, is proposed. Min-norm harmonic retrieval method is an example of high-resolution eigenstructure-based methods. The Wigner-Ville representation was also tested for timefrequency analysis of electric signals. The high-resolution methods do not show the disadvantages of the traditional tools and allow exact estimation of the interharmonic frequencies. To investigate the methods several experiments were performed using real and simulated signals, current waveforms at the output of a simulated frequency converter, shunt reactor compensated transmission lines, and compensated AC arc furnace installation. For comparison, similar experiments were repeated using the FFT. The comparison proved the superiority of the new methods.