High Impedance Fault detection based on harmonic energy variation via S-transform

Successfully detecting High Impedance Faults (HIFs) is a challenge for distribution systems’ protection specialists due to the random behavior and low magnitude of the fault current. To contribute to this problem’s solution, this paper proposes a new approach for HIF detection based on the energy variation of the low harmonic orders obtained by the Stockwell transform and an adaptive threshold used to ensure high sensitivity and secure detection. Tests with the IEEE 34-node test feeder were performed using actual HIF currents recorded experimentally at a test field, considering different soil types. The proposed method also considered the HIF distinction from other events, such as capacitor banks and lateral branches switching, transformer energizing, motor starting, and linear and non-linear loads (arc furnace and a rectifier) connection. A thorough analysis regarding false operation has shown that the proposed approach is effective for distinguishing HIFs from other events. Furthermore, test results indicated that the method is a secure and promising technique for HIF detection, even with noise in the current measurements.