基于Nuttall窗的三峰插值谐波算法分析

针对快速傅里叶变换(FFT)在非同步采样下存在检测精度低的问题,根据Nuttall窗的旁瓣特性以及FFT后信号的谱线特点,提出一种基于Nuttall窗三峰插值的电力系统谐波检测算法。用曲线拟合得到修正公式,并基于修正公式进行了Matlab仿真。仿真结果表明,在同等条件下,该算法处理信号的幅值修正相对误差小于2.44×10-5%,相位修正相对误差小于0.004%。该算法相对于单峰及双峰插值精度更高,相比于五点、九点算法,所提算法可以提前得到修正公式无需对离散序列重新组合。

An approach for harmonic analysis based on Nuttall window and triple-spectral-line interpolation

It is difficult to perform accurate harmonic analysis with Fast Fourier Transform (FFT) under the unsynchronized sampling conditions. According to the components of the sidelobe characteristic of the Nuttall window and signal discrete spectrum characteristic by FFT, an approach for power harmonic analysis based on Nuttall window and the triple-spectral-line Nuttall window interpolation is proposed. The modified formula is obtained by using polynomial fitting method and Matlab simulation of the power harmonics is made based on it. The simulation results indicate that under the same condition, the amplitude correction errors are less than 2.44×10-5 %, as well as that of the calculation phases no more than 0.004%. It has higher analysis accuracy comparing with single-spectral-line interpolation and double-spectral-line interpolation. Compared to the five points' and the nine points' algorithm, the application rectification formulas is obtained without the need to get the spectral sequence.