Research on Harmonic Detection Algorithm Based on apFFT

With the improvement of train speed of high-speed railway, the traction power and traction current are increasing. In order to evaluate the influence of traction current harmonic and inter-harmonic on train signal system, accurate detection of harmonic and inter-harmonic is urgently needed. This paper proposed an algorithm based on the all-phase fast Fourier transform method (apFFT) to realize accurate detection of harmonic and inter-harmonic. Firstly, the harmonic and inter-harmonic steady-state model are constructed, and the continuous and discrete time characteristics of the signal are analysed. Secondly, on the basis of theoretical analysis, the apFFT method has the characteristics of high amplitude accuracy and phase invariance by comparing with the traditional FFT method. Finally, the detection results of harmonic signal and inter-harmonic signal show that the apFFT method is significantly improved in frequency accuracy, amplitude accuracy and phase accuracy comparing with other FFT algorithms.