基于四项余弦窗四谱线插值FFT的电力谐波算法分析

发布时间：2018-03-31 16:57

本文选题：谐波分析　切入点：快速傅里叶变换　出处：《沈阳农业大学学报》2016年06期

【摘要】：快速傅里叶变换是谐波检测中的主要方法,但在谐波分析中很难做到同步采样、整数周期截断,从而造成频谱泄露影响谐波测量的准确性。为了提高谐波的检测精度,利用FFT分析了Nuttall窗的旁瓣特性和四谱线插值算法。提出了一种基于4项3阶Nuttall窗四谱线插值的电力谐波检测算法,该算法通过分析加Nuttall窗信号傅里叶变换的频域表达式,利用谐波频点附近的4根离散频谱的幅值确定谐波谱线的准确位置,进而得到谐波的幅值、频率及相位。通过用曲线拟合函数求得实用的修正公式,简化了复杂的计算过程,并对修正公式进行了Matlab仿真。仿真结果表明:所提出的算法在非同步或非整周期采样时对谐波幅值和相位的检测精度较高,应用该算法处理信号的幅值相对误差小于4.29×10~(-6)%,相位相对误差小于5.7×10~(-4)%。相对于双谱线Hanning、三谱线Blackman-harris算法精度得到了显著提高。并结合沈阳农业大学光伏电站并网算例,将研究检测方法对用户型光伏电站谐波进行分析,并且与分析检测结果进行对比来验证本研究方法的有效性。更加有效的检测谐波幅值和相位,有利于更好的减少农业用户光伏电站对电力系统稳定运行的影响。
[Abstract]:Fast Fourier transform (FFT) is the main method in harmonic detection, but it is difficult to perform synchronous sampling and integer period truncation in harmonic analysis, which results in spectrum leakage affecting the accuracy of harmonic measurement.In order to improve the accuracy of harmonic detection, the sidelobe characteristics of Nuttall window and the interpolation algorithm of four spectral lines are analyzed by FFT.A power harmonic detection algorithm based on 4-item third-order Nuttall window four-line interpolation is proposed. The expression of Fourier transform of signal with Nuttall window is analyzed in frequency domain.The accurate position of harmonic lines is determined by the amplitudes of four discrete spectrum near harmonic frequency points, and the amplitude, frequency and phase of harmonics are obtained.By using the curve fitting function to obtain the practical modified formula, the complicated calculation process is simplified, and the modified formula is simulated by Matlab.The simulation results show that the proposed algorithm has a high accuracy in detecting the amplitude and phase of harmonics in asynchronous or non-integral periodic sampling. The relative error of amplitude and phase is less than 4.29 脳 10 ~ (-1) ~ (-6) and 5.7 脳 10 ~ (-1) ~ (-4).The accuracy of the three-line Blackman-harris algorithm is significantly improved compared with the two-line algorithm.Combined with the grid-connected example of photovoltaic power station in Shenyang Agricultural University, the harmonic analysis of user type photovoltaic power station is carried out, and the effectiveness of this method is verified by comparing with the analysis and detection results.More effective detection of harmonic amplitude and phase is beneficial to reduce the impact of agricultural photovoltaic power station on the stable operation of power system.
【作者单位】：沈阳农业大学信息与电气工程学院;
【基金】：辽宁省博士启动基金项目(20131098)
【分类号】：TM711

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