Multicycle Incipient Fault Detection and Location for Medium Voltage Underground Cable

Early and accurate detection of incipient cable faults is of a great interest to the utility industry. Such faults can be classified into subcycle and multicycle types. Although a lot of research has been conducted on subcycle types of faults, little work has been done for multicycle types of faults. This paper proposes a novel method for detecting and locating a multicycle incipient fault in a cable. The incipient fault is modeled as a self-clearing arcing fault. The distortion degree of calculated voltage is used to detect the occurrence of an incipient fault. The degree of match between the measured and calculated waveforms is used to guide the search for the fault distance. The accuracy is further improved by taking into account the incipient fault angle as seen in the voltage waveform and the power loss characteristics. The proposed method has been verified by PSCAD/EMTDC simulations. Lab experiments are also conducted to further validate the proposed detection method.