A technique for extracting time-varying harmonics based on an adaptive notch filter

An algorithm based on the concept of adaptive notch filter (ANF) is proposed for estimation of power system harmonics in time-varying conditions. The ANF is a second-order notch filter that is further furnished with a nonlinear differential equation to update the frequency. The proposed method adaptively decomposes the measured power signal into its constituting harmonic components. Performance of the method is highly immune to environmental and measurement noises. Its structural simplicity constitutes another advantage of the proposed method which renders it desirable from the standpoint of practical implementations