Directional Traveling-Wave Protection Based on Slope Change Analysis

This paper presents a new approach that deduces the fault direction based on the traveling-wave directional principle. The algorithm by means of wavelet transforms decomposes the voltage signals and calculates the spectral energy at selected detail which allows detecting the fault and to choose the phase to make the slope change analysis. This analysis provides a clear indication of fault direction from the comparison of the slope change polarities of the voltage and current at selected phase during quite a short time. The algorithm, which belongs to the ultra-high-speed protecting relaying, is able to discriminate the direction for all kinds of faults and is not affected by the change of the fault angle inception.