A De-nosing Algorithm of Power Quality Signals Based on Decision Criterion of Likelihood Ratio
Qi Bing · Proceedings of the CSEE · 2006
De-nosing of power quality signals is the base of detecting and locating power quality disturbances.In the electric power system,most power quality signals contain obvious break points.Firstly shortcomings of various kinds of present de-noising methods are analyzed.Then a local sliding window is designed for second derivative signals,what'more,it is divided into two windows and the length of the left window is equal to the right one.Finally,the likelihood ratio of mean difference between the left window and the right one is taken as a decision criterion to detect break points and a novel filter based on it is designed.Two usual signals-voltage interruptions and voltage notches are processed with this method,and the results are compared with the ones of the average filter and the median filter.Experiment results show that the de-noising effect of this method is good and it preferably solves the contradiction between protecting local character of signals and restraining noises.In most de-nosing fields of power quality signals,this method has prominent advantage.