一种基于离散小波变换的谐波分析方法

摘要

在离散小波变换的基础上,结合加窗插值FFT,提出了一种组合式谐波分析算法。该算法先用加窗插值FFT计算基波频率,然后对加窗信号进行频率调制,将谐波分量变换成直流或近似直流分量。用离散小波变换分离出这些分量后用于计算谐波幅值和相位。计算机仿真和实验结果表明,该算法可在高噪声污染情况下,准确计算谐波参数,尤其谐波相位角。DSP评估板上的实现证明了该算法可用于实时谐波分析。%This paper presents a new approach based on a combination of interpolating windowed FFT and discrete wavelet transform.In this approach,the fundamental frequency is firstly estimated,using interpolating windowed FFT.Then the input sampled signal is windowed and modulated by two signals with the same frequency as the harmonic frequency.Therefore the harmonic component is transformed into two dc-like components.These components are separated out by discrete wavelet transform to estimate harmonic phase angle and amplitude.Simulation and experimental results prove that the proposed algorithm can be used to estimate accurately harmonic parameters of power signal heavily distorted by noises,especially harmonic phase.Realization on the evaluation board justifies its real-time applicability for harmonic analysis in power systems.