Research of power harmonic detection based on FFT and Wavelet Transform

This paper analyzes the theory of Fourier Transform and Wavelet Transform and analyzes their application and deficiency in power system. Then the paper introduces a new method that combines Fourier Transform with Wavelet Transform for the reason that the FFT has the advantage to analyze steady harmonic, while the Wavelet Transform has the advantage to analyze fluctuant and fast changing harmonic, and which can compensate with each other well. In this method the signals are put through binary wavelet transform into high frequency part and low frequency part. The high frequency part is analyzed to gain the transition characteristic through Wavelet transform; the low frequency is analyzed to gain the stable harmonics parameters through the Fourier transform, so we can not only obtain the stable harmonics parameters, but also determine sudden change signals. At last validity and feasibility of this method are proved by Matlab simulation.