If the frequencies between bus bar and transmission line are much different,the sampling with the same time interval will bring about errors in the Fourier algorithm.

Currently, a number of methods proposed for calculating the phasors of harmonic components of signals using the Fourier algorithm seem to make electrical engineers puzzled as to which to choose from.

After introducing the correlative theory of phaselet algorithm and analyzing Fourier algorithm and improved Fourier algorithm,the ability of eliminating harmonic current and decaying direct current component of these algorithms are analyzed and compared,and conclusions are given.

Influence on some main-apparatus protection performance by adopting DFT-based digital relays;

In order to have fast responding time of microprocessor-based protection, the half-cycle discrete Fourier transform (HCDFT) has been most widely used for fast computing the fundamental frequency component.

Based on the split-step-Fourier-transform and the diffraction theory of hot-image model we made the simulation of the evolvement of hot-image in case of thick nonlinear medium.