A new numeric technique of accurate frequency and harmonics estimation for power system protection and power quality applications

This paper presents a new method of a measuring a magnitude/frequency spectrum of periodical signals, based on discrete Fourier transform (DFT). The main purpose of this method is to reduce the leakage errors under condition of desynchronization between the signal and the generator of samples. Digital modeling of the suggested method shows that accuracy of the estimation of magnitudes of the signal frequency components increases by factor 10-100 if one compares this method with well known others based on the interpolation of samples. This method can be used especially in power system dynamics investigation (power quality, relay protection, UPS tuning, etc).