闪变FFT检测算法的误差分析及修正

摘要

The fast Fourier transform (FFT) method is an algorithm than most commonly used in practical applications,but the traditional FFT method to measure the flicker caused by multiple modulation is not accurate enough relative to the method recommended by International Electrical Commit (IEC).In order to accurately measure the flicker,ithis paper proposed an improved fast FFT method.Using the single-frequency modulation wave and double-frequency one for flicker detection input signal,it compared each processing step between the FFT-based method and the IEC method,found out the error of the FFT-based method,and then proposed correction method.The simulation results show that the flicker estimating results by the modified FFT-based method are consistent with the IEC method,and meet the requirements of IEC standard.The correction method is also applied to flicker estimation containing three-frequency modulation wave.%快速傅里叶变换(FFT)是在实际应用中测量闪变最常用的一种算法,但是传统的快速傅里叶变换算法对于测量含多个调幅波所引起的闪变结果与国际电工委员会(IEC)推荐的测量闪变的方法相比不够准确,存在比较大的误差.为了准确测量闪变,提出了一种基于改进的快速傅里叶变换算法.以单频率调幅波和双频率调幅波为闪变检测输入信号,对FFT法检测闪变的各实现环节与IEC方法进行对比分析,发现FFT检测算法所得的瞬时闪变值与IEC所得的瞬时闪变值有一定的差距,从而找出FFT检测法的误差来源,通过修正瞬时闪变值来达到准确检测的目的.通过MATLAB仿真分析可以看出,基于改进FFT的闪变检测结果与IEC法基本一致,达到IEC闪变测量精度要求.该检测方法实现简单,并且可以拓展应用于含三个及以上的调幅波的闪变检测.