基于五项Rife-Vincent(Ⅰ)窗的四谱线插值FFT谐波分析方法

Quadruple-spectrum-line interpolation FFT harmonic analysis method based on five-term Rife-Vincent(Ⅰ)window

目前,在电力谐波分析中快速傅里叶变换(FFT)应用得最为广泛,但是在非同步采样时,应用该变换容易产生频谱泄漏,出现栅栏效应。为减小非同步采样对FFT的影响,对旁瓣峰值电平小且下降速率快的五项Rife-Vincent(Ⅰ)窗进行了分析,并将它应用于FFT算法中,提出了基于五项Rife-Vincent(Ⅰ)窗的四谱线插值FFT谐波检测算法。经过多项式函数的拟合,得到了简单实用的四谱线插值修正公式,使计算过程更为简单。结果表明,与Hanning窗、Nuttall窗和四项Rife-Vincent(Ⅰ)窗插值FFT相比,相同条件下,五项Rife-Vincent(Ⅰ)窗具有更高的准确度,其幅值相对误差EAh≤6.524×10-5%,相位相对误差Eφh≤7.751×10^(-3)%。

Fast Fourier transform(FFT)is the most widely used method in power harmonic analysis recently.However,in the case of asynchronous sampling,it is easy to generate the spectrum leakage and the fence effect.In order to reduce the influence of asynchronous sampling on FFT,the five-term Rife-Vincent(Ⅰ)window with low side-lobe peak level and fast descent rate are analyzed and applied to FFT algorithm,and quadruple-spectrum-line interpolation FFT harmonic detection algorithm based on five-term Rife-Vincent window is proposed in this paper.Based on the polynomial function fitting,a simple and practical interpolation correction formula of four spectral lines is derived,which makes the calculation process easier.The results show that compared with Hanning window,Nuttall window and four-term Rife-Vincent(Ⅰ)window interpolation FFT,five-term Rife-Vincent(Ⅰ)window has the higher accuracy under the same conditions,and its amplitude relative error E A h≤6.52434×10^(-5)%,and phase relative error Eφh≤7.75054×10^(-3)%.