一种应用于电力系统谐波检测方法的理论研究

Theoretical Study on a Harmonious Detecting Method for Power System

提出了一种小波变换与傅里叶变换相结合的谐波检测方法。利用小波变换的奇异性优点,划分出谐波的高低频部分进而获得谐波信号的稳态与非稳态量。同时对低频部分采用快速傅里叶变换(FFT)法分析,在频域内可确定各次谐波的含量;高频部分信号存在大量的噪音与奇异信号,对此采用小波熵分析法,在时域内求出信号的相关信息。该谐波分析方法在获得信号发生突变的时刻点同时可以进一步将其噪音信号与奇异信号从信号源中剔除,从而提高了电力系统谐波分析的适用性和精确度。通过进一步仿真表明,所提出的谐波检测方案能满足测量各次谐波含有率标准的要求,为谐波检测的工程实际应用提供了理论依据。

A harmonic detecting method of Wavelet Transform and Fourier transform is proposed.With Wavelet Transform advantage of singularity,high and low frequency of harmonic wave were classified to get steady and non steady of harmonic wave.With FFT analysis for low frequency,content of every wave is determined;there is great noise and strange signal in high frequency,so use wavelet entropy to get related information in time domain.When signal has sudden change with this method,its noise and strange signal can be removed at the same time,therefore,applicability and accuracy of analyzing power system harmonic wave are improved.The further simulation showed that this method can meet the requirement of content standard of every harmonic wave,offering theory basis for detecting harmonic wave.