应用FFT进行电力系统谐波分析的改进算法

采用快速傅立叶变换(FFT)进行电力系统谐波分析时很难做到同步采样和整数周期截断，由此造成的频谱泄漏将影响到谐波分析的结果。通过加窗以及采用插值修正算法可以改善计算谐波频率、相位和幅值的准确度。该文针对已有算法存在的问题，提出了一种基于两根谱线的加权平均来修正幅值的双峰谱线修正算法，利用距谐波频点最近的两根离散频谱幅值估计出待求谐波的幅值；同时，利用多项式逼近方法获得了频率和幅值修正的计算公式，这些改进能够进一步降低泄漏和噪声干扰，提高谐波分析的准确性。基于该改进方法，文中推导了一些常用窗函数的实用修正公式。仿真结果验证了该改进算法的有效性和易实现性。

AN IMPROVED ALGORITHM FOR HARMONIC ANALYSIS OF POWER SYSTEM USING FFT TECHNIQUE

There are difficulties in performing synch-ronized sampling and integral period truncation in the harmonic analysis of power system with the fast Fourier transform (FFT) technique. However, not to satisfy these conditions, the results will be disturbed by the frequency leakage. Some efforts have been made including the utilization of window functions and interpolation algorithms to correct the measured frequency, phase and amplitude by FFT. In order to overcome some shortcomings of existing correction methods, an improved algorithm is present in this paper, with which the amplitudes of harmonics can be estimated from the two neighboring spectral lines. The polynomial approximation method is also employed to obtain simple formulas for frequency and amplitude correction. By these methods, the disturbance of the frequency leakage and the noise can be reduced and the accuracy of the harmonic analysis can be improved. Based on the proposed algorithm, the practical correction formulas for some typical window functions are developed. The simulation results have verified the effectiveness and practicability of the algorithm.