Harmonic analysis method based on multiple modulation zoom analysis and interpolating windowed FFT method

Since many power electronics equipments and nonlinear loads were accessed, more and more harmonics and inter-harmonics occurred in power system. But when the analyzed signal contains components with frequency close to each other, precise analysis can not be made by traditional harmonics analysis methods such as interpolating windowed FFT method. In this paper, first a new method-multiple modulation zoom analysis based on complex analytic bandpass filter is adopted to make an accurate analysis to this kind of components. Then the remaining components are also analyzed by traditional method. Simulations compared to direct interpolating windowed FFT method show that the proposed method can make a much better analysis with higher frequency resolution and so effectiveness of this method is demonstrated.