Traveling Wave Based Single-Phase-to-Ground Protection Method for Power Distribution System

Correct detection and identification of single-phase to-ground faults not effectively grounded in distribution systems is a major challenge for protection engineers. This paper proposes a novel traveling wave based protection method to solve this problem. The proposed method compares the polarities of current and voltage traveling waves measured immediately after the fault inception to determine the fault direction. Nuisance tripping is avoided by using the power frequency voltages detected on the busbar to inhibit operation. The power frequency voltages ensure that the system does not mal-operate due to noise and also provide discrimination for phase-to-phase and three-phase faults. The wavelet transform and modulus maxima theories are used to extract the polarity of traveling waves measured at the relaying point. The simulation studies demonstrate correct operation of protection, which is independent of fault distance, fault inception angle, fault path resistance, and the method used for neutral grounding.