基于泄漏对消的电力谐波相角高精度估计算法

采用快速傅里叶变换(FFT)进行电力系统谐波分析时,受频谱泄漏和栅栏效应的影响,相角估计误差往往较大.为减小这类误差,提出一种基于频谱泄漏对消的谐波相角高精度估计算法,结合余弦组合窗时域和频域特性,综合考虑长、短范围频谱泄漏的影响,推导了基于余弦组合窗的插值FFT谐波相角计算式.该算法首先运用基于余弦组合窗的插值FFT方法获得频率偏差估计值,然后采用离散频谱泄漏对消方法进行信号谐波相角估计,实现简单,准确度高.非同步采样情况下,采用典型余弦组合窗(Hanning、Blackman、Blackman-Harris、Rife-Vincent(I)、Nuttall等)进行信号谐波相角估计的仿真实验与应用验证了本文算法的准确性和有效性.

High accuracy phase estimation algorithm based on spectral leakage cancellation for electrical harmonic

Due to spectral leakage and picket fence effect, the phase estimations are normally different from the real ones when using FFT method for power system harmonic measurement. In order to improve harmonic phase estimation accuracy, an algorithm based on spectral leakage compensation is presented. The expressions of phase estimations are derived considering the long-range and short-range spectral leakage based on the characteristics of the cosine-class windows. First, the displacement term of frequency is estimated by windowed interpolated FFT algorithm. Then the phase estimation is obtained by cancellation of spectral lines. Last, simulation and experimental results are presented, which show the effectiveness of the method in estimating phase with non-synchronous sampling using Hanning window, Blackman window, Blackman-Harris window, Rife-Vincent (I) window and Nuttall window.