高频间谐波引起闪变的时频混合测量方法

A Hybrid Time and Frequency Domain Method for Flicker Measurement Caused by High-frequency Interharmonics

国际电工委员会(IEC)闪变仪无法准确测量高频间谐波引起的峰值波动闪变,为此提出了一种改进的时域和频域混合方法用于高频间谐波引起的闪变测量。在时域方面,采用一种同步解调方法替代IEC方法中的平方解调以提取高频间谐波引起的波动信号,该方法首先采用一种简单的方法提取基波同步信号,然后将该信号的奇次方进行配比运算得到同步的谐波信号集合,最后则通过谐波信号集合对原始信号进行运算以实现对高频间谐波信号的解调。在频域方面,则采用递推傅里叶变换对不同频率分量进行视感度加权的方法代替原有的视感度加权滤波器,以弥补视感度加权滤波器无法准确模拟视感度曲线的缺陷。在Labview中搭建了相应算法的模型,通过实验证明了所述算法能准确检测高频间谐波引起的闪变。最后还通过所述方法制定了单个间谐波和间谐波对决定的间谐波闪变曲线,分析了不同频段间谐波闪变限值的特点。

IEC flickermeter cannot accurately measure peak fluctuation flicker caused by high-frequency interharmonics,therefore,an improved hybrid time and frequency domain method for the flicker measurement caused by high-frequency interharmonics is presented here.In the time domain,a synchronous demodulation method is used to replace square demodulation of the IEC method to extract fluctuant signal caused by high-frequency interharmonics.Firstly,a simple method is used to extract the synchronizing fundamental signal,then ratio operation is performed to odd power of the signal to get synchronous harmonic signal set,and finally the high-frequency interharmonic signals are demodulated through operating the original signal with harmonic signal set.In the frequency domain,the recursive Fourier transform is used,and then,different frequency components are weighted according to a visual sensitivity curve.This process is used to compensate for the defect that visual sensitivity weighting filter cannot accurately simulate the visual sensitivity curve.Corresponding algorithm model is built in Labview,experiments are conducted to prove that the proposed algorithm can accurately detect the flicker caused by high-frequency interharmonics.Finally,the interharmonics flicker curve caused by a single interharmonic and a pair of interharmonics is obtained through the proposed method,and the characteristics of interharmonics flicker limits of different frequency bands are analyzed.