A Detection Method of Harmonic and Interharmonic Using Window Interpolation and Complex Modulation Refinement Algorithm

When there is interharmonics in the vicinity of the fundamental or harmonics, the serious spectral interference will affect the detection accuracy of harmonics and interharmonics. In this paper, a comprehensive analysis method combined window interpolation with multiple modulation zoom spectrum is proposed. Based on the phase difference between the maximum and the second largest lines in the mainlobe of the windowed signal, the method determines whether the peak line has mainlobe interference. If mainlobe interference exists, the multiple modulation zoom spectrum is refined in a certain frequency range with the maximum spectrum as the center frequency, and the harmonic and interharmonics parameters near the frequency band are obtained. If there is no mainlobe interference, the harmonic and inter-harmonic parameters at the frequency band are obtained directly by windowed interpolation. The other harmonics and interharmonic components of the signal are obtained by repeating the above steps. Finally, the simulation results show that the proposed method can effectively dispose the complex signals of harmonics and interharmonics with closing frequencies.