基于Blackman-Harris相位差校正信号谐波分析方法

Harmonic Analysis Based on Blackman-Harris Window and Phase Difference Correction

运用快速傅里叶变换(FFT)进行电力谐波分析时很难做到同步采样和整周期截断,造成的频谱泄漏将影响谐波分析精度。本文引入Blackman-Harris窗函数,分析其时域和频域特性,采用Blackman-Harris窗对谐波信号进行加权,结合相位差校正原理,用于谐波分析。推导了信号基波及各次谐波频率、幅值和初相角的计算式,对常规的频谱相位差校正方法进行了改进。仿真结果表明,应用Blackman-Harris窗相位差校正信号谐波分析法的运算时间与加其他余弦窗的运算时间相比没有明显增加,计算精度却显著提高。本文提出算法实现简单,精度高,通用性强,可应用于高精度电能计量和电能质量分析。

It is difficult to perform synchronized sampling and integral period truncation in the harmonic analysis of power system with the fast Fourier transform （FFT） technique. However, without the satisfaction of both these conditions, the acecracy can be influenced by the frequent leakage. Therefore, the Blackman-Harris window function is introduced to analyze the characteristics of time and frequency domains. Harmonic signals are weighteed by the Blackman-Harris window, and analyzed by combining the principles of phase difference correction. Then the calculation formulae of fundamental and harmonics of the signal frequency, amplitude and initial phase are deduced. Moreover, the spectrum of the conventional phase difference correction method is improved. Simulation results show that there is no obvious increase in the computing time comparing the Blackman-Harris window with other cosine window, while the accuracy of calculation is significantly improved by applying Blackman-Harris window. It can be concluded that the algorithm proposed in this paper is simple with high accuracy and versatility which can be applied to high-precision energy measurement and power quality analysis.