High impedance fault detection method based on the short-time Fourier transform

A method to detect high impedance faults (HIFs) based on low-order harmonics is proposed. Short-time Fourier transform (STFT) is used to extract the main harmonic components of phase current, as magnitude and phase of the third harmonic and magnitude of the second and fifth harmonics, which are used to identify HIF occurrence. In addition, this study presents an analysis of the window length and type used in STFT and its suitability for the application. The method proposed is able to detect HIF occurrence at various points of the test system, as well as HIF happening on different soil surfaces. It is also capable of distinguishing HIF events from similar distribution system disturbances such as capacitor banks switching and feeder energising. Furthermore, it is effective when real HIF oscillography is applied, indicating its tolerance to typical noises present on real signals.