含分数次谐波环境下提取整数次谐波信息的新方法

Multiple harmonics extraction from signal with fractional harmonics

提出了一种在含有分数次谐波环境下,以一定的规律逐渐降低的频率序列依次作为基频,利用傅里叶级数展开电力系统中实际的电压、电流信号,再通过迭代算法从中提取出工频量及其整数次谐波分量信息的新方法。该方法回避了现有的加窗DFT算法中选取窗函数困难的问题。新方法的原理进行了详细的数学推导和说明,并给出程序框图。为了验证方法的正确性,利用程序对一实际信号进行了分析。实例结果表明,与传统的FFT算法比较,新方法在富含间谐波和次谐波环境下依然能够提出基波和整数次谐波的幅值和相角,且精度满足工程需求。同时,该方法还具有实现简单等优点,易于在工程实际中应用。

A method is proposed to extract the power frequency fundamental and its multiple harmonics from the signal with fractional harmonics,which decreases the frequency successively as the fundamental according to a specific law to expend the real voltage and current signals of power system based on the Fourier analysis,and then extracts the needed fundamental and harmonics by iterative algorithm,avoiding the window function selection of windowed DFF. Its principle and flowchart are given. Analysis of a real signal shows that,compared with the conventional DFF,this method extracts the power frequency fundamental and its multiple harmonics from the signal with rich inter-harmonics and sub-harmonics,meeting the engineering requirements for accuracy. It is simple in implementation and easv in engineering application.