Security and Speed Assessment of a New Distance Protection Algorithm Based on the Wavelet Transform

Distance relay algorithms are typically based on the phasor-domain approach where the fundamental frequency phasors are computed using well-known methods such as: the full cycle discrete Fourier transformation (FCDFT), least error squares (LES) and the discrete wavelet transform (DWT). Instead of the phasor-domain approach, there are time-domain based algorithms that detect faults without calculating the phasors. In this paper a new distance relay algorithm based on the time-domain approach and DWT is introduced. The security of fault detection and the tripping time obtained when applying the proposed algorithm to a number of fault simulations is compared with the equivalent results obtained when applying the classical solution based on DFT.