基于Pisarenko谐波分解的间谐波估算方法

随着电力系统的发展以及非线性电力元件的大量应用，电网中的谐波状况更加复杂化，非整数次谐波分量——间谐波和次谐波变得较为突出。文章应用Pisarenko谐波分解(PHD)原理来计算谐波和间谐波的频率和幅值。该方法基于信号自相关估计将信号的特征空间划分成信号子空间与噪声子空间，根据这两个子空间正交的原理构建特征多项式和代数方程组，从而计算出各种谐波分量的频率和幅值。由于该方法假设各频率分量的相位是随机分布的，无法给出谐波的相位信息。文章还结合整数次谐波、间谐波和次谐波估算仿真实验分析了PHD方法的敏感因素。并针对电力系统中谐波分量和基波分量能量相差较大影响估计结果的问题，提出了低通差分预处理的解决方法，取得了较好的估算效果。

INTER-HARMONICS ESTIMATION BY PISARENKO HARMONIC DECOMPOSITION METHOD

Along with the development of electric power system and the wide application of nonlinear equipments or devices, the harmonics in power networks became more complicated, besides the harmonics of integer times to fundamental component the inter-harmonics and sub-harmonics exist and are in special status. Here, the Pisarenko harmonic decomposition (PHD) method is applied to calculate the frequencies and magnitudes of various components. Based on the signal auto-relation matrix the PHD method divides the eigen-space partition into signal subspace and noise subspace and according to the principle that the two subspaces are orthogonal the eigenpolynomial and algebraic equations are constructed to obtain frequency and amplitude of each order of harmonics respectively. Because in PHD method it is assumed that the phase angles of various frequency components of harmonics are randomly distributed, so the phase angle information cannot be obtained. Combining the given example, the susceptibility factors of PHD method are analyzed. For the phenomenon that the estimation results are affected by the difference between the energy of harmonic components and that of the fundamental component, a solution of low-pass differentiator are proposed and a better result is obtained.