High impedance fault detection based on Stockwell transform and third harmonic current phase angle

A new method for high impedance fault detection is proposed in this paper. Stockwell transform is used to extract the third harmonic current phase angle, measured only at the substation, whereas the moving standard deviation continuously monitor this parameter. The fault is detected when the standard deviation is below a self-adaptive threshold for a predetermined period of time. To validate the method, a real distribution network is adopted, considering a modeled stochastic noise based on real current signals. Results show that the proposed method is able to quickly detect high impedance faults in different types of contact surface and fault locations, without causing false positives. It can also differentiate high impedance faults from other distribution network disturbances such as capacitor banks switching, feeder energizing and low-impedance faults. Moreover, results suggest that the proposed method is not affected by fault location or inception angle, system loading and topology changes in the distribution network.