A class of half-wave symmetry characteristics of the grid harmonic detection method research

An improved FFT algorithm considering the half-wave symmetric characteristic of the power system signals is presented based on the conventional FFT method.The new FFT algorithm analyzes only the odd harmonics in its calculation and omits the need for calculation of the even harmonics.So the calculation of the algorithm just has a half amount of the traditional FFT.It can improve the speed of the analysis of harmonic.On the base of this,an adaptive frequency tracking algorithm and processes were proposed to achieve accurate frequency tracking and harmonic analysis,in order to solve the problem of non-synchronous sampling.MATLAB simulation and experimental results show that the new algorithm and processes increase the speed and accuracy of responsible,effectively suppresses the sudden change impacts of frequency and phase of the grid.So it is a practical engineering method over the conventional method.