The algorithm of interpolating windowed FFT for harmonic analysis of electric power system

The Fast Fourier Transform (FFT) cannot be directly used to the harmonic analysis of electric power system because of its higher errors, especially the phase error. This paper discussed the leakage phenomenon of FFT and presented a new amending algorithm, poly-item cosine window interpolation, which based on the interpolating algorithm proposed by V. Jain and T. Grandke. This new algorithm obviously improves the accuracy of the FFT, so it can be applied to the precision analysis for electrical harmonic. The simulating result shows that applying different windows has different effects to the accuracy, and the Blackman–Harris window has the highest accuracy.