Evaluation of High Impedance Faults in Delta 13.8 kV Distribution Network

Abstract

The detection of high impedance faults is a challenge for most Power Utilities Companies. This work presents the results of computer simulations of laboratory and field tests to verify the behavior of the currents and voltages to the detection and classification of high impedance faults. Waveform's data were produced by ATP (Alternative Transient Program) and oscillographs were obtained by laboratory and field tests related to broken cable on grass, asphalt, concrete, and clay surfaces. The test system is composed of a substation with 34.5-13.8 kV power transformer Wye-grounded-Delta., a 13.8 kV bus, and three rural distribution feeders. The 13.8 kV delta bus is connected to a Zig-Zag Grounding Reactor. The dataset obtained was evaluated and rules had been created for detecting and classifying high impedance faults. The residual current, residual voltage, and ratio V2/V1 show a characteristic behavior and allow create a method for high impedance fault detection and classification. The method performance was reliable, with true results higher than 80% for real feeder tests.