Research on a Novel Traveling-Wave Protection Using Mathematical Morphology for Transmission Line Unsymmetrical Grounded Faults

There are two primary troubles having effect on reliability in tradition traveling-wave distance protection schemes. One is reflection wave identification for single-ended traveling-wave protection (A-type), and another is time synchronization for two-ended traveling-wave protection (D type). This paper proposes a novel protection for transmission line unsymmetrical grounded faults, which only needs initial traveling wave. The protection principle is based on the propagation time difference between aerial- and zero-mode traveling waves. The propagation time difference rises monotonously with the fault distance increasing. The protection scheme is designed both single- and two-ended type. The protection algorithm is implemented with Mathematical Morphology Gradient (MMG), which detects the traveling-wave arriving time. The performance of the traveling-wave protection scheme is investigated with a number of PSCAD/EMTDC simulation data under various fault situations. Theoretical analysis and testing results demonstrate the proposed novel protection scheme is feasible, and has a certain potential in fault location.