A DFT-based approach for efficient harmonic/inter-harmonic analysis under time-varying conditions

This paper presents a new approach for harmonic/inter-harmonic analysis in power systems. The method is based on phase error of discrete fourier transform (DFT) when an asynchronous sampling is performed. simple moving average filters (MAF) are used to eliminate the oscillatory results of DFT. Linear equations are used to estimate the frequency of each component present in the input signal. The estimated frequency is used to correct the DFT smoothed amplitude by means of a polynomial curve fitting of the frequency response of the DFT. This method takes advantage of the recursive formulation of DFT, resulting in a low cost computational algorithm.