Fast harmonic computation for digital relaying

It has been shown that the fast Fourier transform of a sequence which slides over a time-limited rectangular window can be carried out in a nonrecursive manner by means of O(N) computations. The same idea is applied in this paper to the digital relaying field, where only certain isolated harmonics, rather than the full spectrum, are needed, leading to O(log₂N) computations per harmonic. The particular case N=16 has been used for comparison purposes, showing that the new technique is less expensive than other nonrecursive algorithms in the literature