基于快速傅里叶变换和db小波变换的谐波检测

在电力系统谐波检测中,使用快速傅里叶变换法(FFT)可以得到平稳谐波信号中的频谱,从而可以确定该信号中谐波的频率和幅值等信息.但FFT局限于得到信号的频域信息,很难检测到谐波发生的具体时刻,而小波变换可以捕捉到信号中的细节部分.针对复杂谐波信号,提出了一种将快速傅里叶变换和小波变换相结合的检测方法.由Matlab仿真结果可知,该方法可以检测稳态谐波,确定暂态谐波的突变时刻.

Harmonic Detection Based on FFT and db Wavelet Transform

In the harmonic detection of power system,Fast Fourier Transform(FFT) is applied to get the Spectrum of the steady-state harmonic signals so that the frequency,amplitude and other information of the harmonics in the signal can be determined.Since the FFT is limited to obtaining the frequency domain information of the signal,it is difficult to detect the specific moment of occurrence of harmonics,but the Discrete Wavelet Transform (DWT)can capture the details of the signal part.Aiming at complicated harmonic signals,a method is presented to combine FFT and wavelet transform.The simulation results by Matlab show that the method can detect the steady-state harmonics and determine the sudden change of transient harmonics.