Abstract:Windowed interpolation fast Fourier transform (FFT) algorithms are currently the most commonly used method for harmonic analysis.When the signal contains harmonic/inter-harmonic components with closing frequencies,the main-lobe jamming usually exists in the frequency spectrum,which seriously affects the accuracy of windowed interpolation FFT.To solve this problem,the phase-frequency characteristics of main lobes are studied and a method for checking whether the main-lobe jamming exists is proposed,which can identify harmonic/inter-harmonic components with closing frequencies.Simulation experiments verify the effectiveness and accuracy of the proposed method.