For the frequency spectrum leakage and fence effect generated in Fast Fourier Transform (FFT) during asynchronous sampling and integral period truncation affect the precision of harmonic detection, a new algorithm for harmonic analysis based on four-spectrum-line interpolation FFT with second-order self-convolution window with five-term Maximum-Sidelobe-Decay (MSD) was proposed and the polynomial fitting method was used to construct the four-spectrum-line interpolation correction formula. The simulation results showed that this algorithm could improve the detection accuracy of amplitude, phase and frequency by 1–2 orders of magnitude compared with other commonly used windowed interpolation algorithms.

针对异步采样和积分周期截断过程中快速傅立叶变换（FFT）产生的频谱泄漏和围栏效应影响谐波检测精度的问题，提出了一种基于二阶自谱四线谱插值FFT的谐波分析新算法提出了具有五项最大Sidelobe衰变（MSD）的卷积窗口，并采用多项式拟合方法构造了四谱线插值校正公式。仿真结果表明，与其他常用的窗口插值算法相比，该算法可以将幅度，相位和频率的检测精度提高1-2个数量级。