Ensuring power quality in power systems demands fast calculation of harmonics. In this paper, a recursive algebraic approach to the calculation of current transformer (CT)-derived current signal frequency and harmonics is proposed that is based on a fast but accurate recursive algorithm whereby in any stage of sampling in a given cycle the variables are calculated on the basis of their values in the previous stage. Comparison with the discrete Fourier transform (DFT) approach shows the superiority of the proposed approach. It is shown that when the number of samples used in the DFT approach is increased, the results obtained approach those ofthe proposed recursive algebraic method.

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