An On-Line Monitoring Method of Interharmonics Based on ANF and Interpolated FFT

Abstract

To detect interharmonics whose amplitudes are often small, a detection method based on ANF and interpolated FFT is proposed. In the method, the parallel structure of the ANF (adaptive notch filter) is firstly used to detect the fundamental and harmonic components, in which the fundamental frequency signal with high amplitude is detected with the main ANF and then the measured base frequency is output to sub-parallel ANF structure so as to extract the harmonic components. Then a separated interpolated fast Fourier transformation (FFT) analysis of interharmonic components will be effectively completed without the influence of the fundamental and harmonic components. A detection platform based on the proposed method is implemented in LabVIEW. The results of simulation and experiments show the effectiveness of the method.