A Novel Fast Filtering Algorithm for Removing Decaying DC Component

摘要

The Fourier Algorithm can not remove the influence impacted by the decaying DC component to the computation precision of fundamental frequency* component The improved Fourier algorithms have the capability of eliminating the influence impacted by the decaying DC component to the computation precision of the fundamental frequency component, but can't meet the need of high speed protection because of requiring long data window. High speed protection algorithms, such as variable window algorithm and phaselet-based algorithm, are severely affected by decaying DC component and high frequency components because of calculating the fundamental frequency component via short data window. P re-low-pass filter can remove high frequency components but can't remove decaying DC component. A novel fast filtering algorithm for removing decaying DC component is presented in this paper. The presented algorithm can only use three samples to extract fundamental frequency component directly from the sample signals thus can be employed by various high speed protection algorithms. Based on the analysis to the influence impacted by the estimation error of time constant to the computation accuracy, a method is given how to calculate the value of time constant when the algorithm is put into practice. The presented algorithm requires small calculation, but has high accuracy and is not sensitive to the estimation error of the time constant. The presented algorithm has no limitation to the protection algorithms. The validity of the presented algorithm is tested via numerical example.