DFT based phasor estimation algorithm for numerical digital relaying

A novel phasor estimation algorithm is proposed, by means of an innovative modification of the traditional full cycle discrete Fourier transformer (FCDFT) algorithm. The main idea is to combine the FCDFT outputs for even and odd sample-setsobtained for one cycle data window decimated by two and by four. Its performance was compared with the ones of other full cycle algorithms reported in the late literature on the subject. The obtained results reveal the proposed algorithm leads to the best performance, even considering both the decaying DC component of the fault current and the one caused by the current transformer secondary circuit.