Simplified algorithms for removal of the effect of exponentially decaying DC-offset on the Fourier algorithm

The impact of exponentially decaying direct component on the Fourier algorithm is theoretically investigated first in this paper. A new algorithm to eliminate the error caused by this decaying component in the Fourier algorithm has been proposed. Furthermore, three simplified methods are proposed to alleviate the computation burden. The performance of the Fourier algorithm improved with these methods along with the least error squares algorithm is evaluated using a simple network and a real power system modeled by EMTP. The evaluation results are presented and discussed.

I. Introduction

THE Fourier algorithm is one of the most popular algorithms used for variety of measurements in control and protection applications [1]. It is used to accurately extract the harmonic components if the following assumptions are satisfied. •

The highest frequency of input signal is less than , where N is the number of sampling points per fundamental frequency cycle.

•

There is no exponentially decaying direct component.