High impedance fault detection using orthogonal transforms

High impedance fault (HIF) detection is very important to utility companies in terms of safety (a threat on human lives), specifically, in power systems and power delivery. In this paper, two groups of fault events from official websites of DOE/EPRI National Database Repository of Power System Events are studied, and a heuristic approach specified for these particular groups of events is applied for developing a reliable detecting method. We investigate two HIF detection methods by applying sliding orthogonal transforms such as fast Fourier transforms (FFTs) and Walsh Hadamard Transforms (WHTs) to its harmonic-current content. The criteria to declare the existence of fault currents are based on the threshold and shape of the magnitude and phase responses of orthogonal transformed results. Simulation shows that both sliding FFT and WHT are effective techniques for HIF detection in studied cases.