The basic principle of protective relaying of power systems has not changed for more than half a century. Almost all power system protective relaying algorithms are dominated by integral transforms such as the Fourier transform and the wavelet transform. The integral transform can only provide an average attribute of the s- nals or their components. The accuracy of the attribute extraction is signi?cantly sacri?ced by the assumption of periodicity of the signals if the integral transform is appliedto transientsignals. Itis also wellknownthatthe signalsare liable to bec-...