Aiming at the shortcomings of large computing capacity about the commonly used interpolation FFT algorithm that combined with complex window function, by comparing different windows and analyzing a good side lobe characteristic of Rife-Vincent window, an improved algorithm of multi-spectrum-line interpolation based on 4-term Rife-Vincent (I) window is proposed. After analyzing the signal model in frequency domain, and using the phase characteristic of adjacent spectrum lines in main lobe of window, the amplitudes of three neighboring spectrum lines near the harmonic frequencies are used to locate the accurate position of the harmonic spectrum lines, eventually, the correction formulas of amplitude and frequency deviation can be obtained, which can greatly reduce the computing capacity and improve the real-time performance, as well as satisfy the requirement of accuracy of harmonic analysis. The simulation results show that the proposed method in this paper can effectively overcome the influence of frequency fluctuations, enhance the accuracy of harmonic measurement, and can effectively restrain the influence of white noise.
