Proposição de um método de detecção de FAI baseado nos componentes harmônicos de baixa frequência.

Abstract

A method to detect high impedance faults (HIF) based on the low order harmonics is proposed on this dissertation. The Short-Time Fourier Transform (STFT) is used to extract the main harmonic components of the phase current, which are used to identify a HIF occurrence. Additionally, the work presents an analysis on the window size and type used in the STFT and its suitability for the application. The method is validated using two databases: one containing HIF simulated signals mixed up with capacitor banks switching and feeder energizing singals, and another containing only actual HIF oscillograms. The proposed method is able to detect HIF occurring in various points of the test-system, as well as HIF happening on different types of soil surfaces. It is also able to distinguish HIF from the other tested disturbances. Futhermore, the method tolerates typical noises present on real signals, since it proved to be effective in all the applied cases.