基于VSS窗的改进相位差电力谐波分析方法

Improved Phase Difference Method Based on Variation Semi-Sinusoidal Window for Power Harmonic Analysis

利用快速傅里叶变换(FFT)进行谐波分析时,在非同步采样和非整数周期截断条件下存在频谱泄露和栅栏效应,影响谐波的分析精度。采用传统的窗函数对信号进行加权,虽然可以减小频谱泄露和栅栏效应的影响,但其效果受到窗函数旁瓣特性的制约。提出一种基于衍生半正弦窗的改进相位差电力谐波分析方法。该方法引入一种新的窗——衍生半正弦窗,对信号进行加权,然后采用改进相位差算法分析谐波参数——幅值、频率、相位。衍生半正弦窗可以通过调整指数获得满足要求的旁瓣特性,能较好的抑制频谱泄露,在工程应用中具有很大的灵活性。推导了信号基波及各次谐波频率、幅度、初相位的求解公式。仿真实验结果表明,提出的基于衍生半正弦窗的改进相位差算法具有较高的计算精度。

When Fast Fourier Transform（ FFT）is adopted to realize harmonic analysis,there is a spectrum leakage problem and the occurrence of the picket fence effect in the harmonic analysis of power system under asynchronous sampling and non-integral period truncation conditions,which will affect the analytical precision of the harmonic. Although the signal weighted by traditional windows can suppress the spectrum leakages,the analysis result is restrict-ed by the sidelobe characteristics of these windows. An improved phase difference method based on variation semi-sinusoidal window for power harmonic analysis is proposed in this paper. A new variation semi-sinusoidal window is applied to weight the signal by this method. Then,the improved phase difference method is employed to calculate the parameters of the signal,such as frequency,amplitude and phase. The satisfying performance of the sidelobe of varia-tion semi-sinusoidal window can be obtained by adjusting the index value,which will suppress spectrum leakage and possess flexiblility in practical engineering. Moreover,the calculation formulae of the frequencies,amplitudes and ini-tial phases of fundamental and harmonics are deduced. The simulation results indicate that the proposed method can estimate harmonic parameters with high accuracy.