High Impedance Fault Location Characterized by Fourier, Stockwell and Wavelet Transforms
Gabriela Nunes Lopes1; Luiz Henrique Pessôa da Costa Trondoli1; José Carlos de Melo Vieira Júnior1; José Rubens Macedo Jr.2
1 Universidade de São Paulo - USP; 2 Federal University of Uberlândia
Resumo
The low magnitude and the erratic behavior of High Impedance Faults (HIFs) current in electrical distribution systems make its detection a challenging task, because it hinders a reliable and fast detection by conventional protection methods. Besides that, HIFs can cause danger and affect utilities quality of service. Thus, before proposing a detection method, characterizing HIF by viable tools is needed. Therefore, this work aims at characterizing this type of fault considering its propagation along a medium voltage distribution feeder - the IEEE 34 node test system. To reach such a goal, Fourier, Wavelet and Stockwell transforms were applied in the substation current during the fault period. The purpose is to highlight the essential characteristics obtained by each transform and, at the same time, evaluate their use as a promising tool for HIF detection at any location in the system. The results showed the presence of low-frequency harmonics in the current waveform, regardless the fault location. Besides that, considerable energy amplitude variation of the current frequencies during the fault period was identified. Thus, both the energy and the energy variation of the harmonic content enable the HIF characterization, even for situations where the fault location is far from the measurement spot.
Palavras-chave: high impedance fault; Fourier transform; Stockwell transform; Wavelet transform; electrical distribution systems