基于加窗插值FFT的电力谐波测量理论（Ⅱ）双插值FFT理论

Power Harmonics Measurement Based on Windows and Interpolated FFT(Ⅱ) Dual Interpolated FFT Algorithms

本文用四项Ｂｌａｃｋｍａｎ－Ｈａｒｒｉｓ窗对采样数据加权，再用两次插值快速精密地计算出信号的谐波参数。与国外有关算法相比，达到相同的计算精度，本文提出的算法所需的采样频率约为国外通常使用的１／３左右。在信噪比大于４０ｄＢ时，一般信号谐波幅值、频率和相位精度分别可达０．５级、０．１级和１级。

This paper proposes a new power harmonics measurement. The 4-term Blackman-Harris window is used for windowing the sample data so that the spectral leakage errors are largely decreased, and then, dual interpolations are used to obtain harmonic parameters. Compared with the algorithms published previously, to reach the same precision,this algorithm only needs the sampling frequency of about one third. When signal noise ratio(SNR) is more than 40dB, the calculation precisions of the magnitude, the frequency and the phase of harmonics is better than 0.5%, 0.1% and 1%.