A new approach to fault location in a single core underground cable system using combined fuzzy logic and wavelet analysis

Electric utilities often face the problem of finding the exact location of a fault in a distribution cable. These faults often occur at the worst possible time and cause the maximum amount of inconvenience to the utility´s customers. Most fault location techniques in use today require the judgment of skilled operators, can also produce less than desired results for rapid fault location and thus may inflict additional damage to the cable. When a fault occurs in a cable, there are specific relationships between fault voltage, fault current, the resulting fault impedance and location. Thus, with regard to fuzzy logic which is an effective way to map an input space to an output space, it can be employed in fault location as an efficient, economic and adaptable method (compared with other artificial intelligence systems) by simply representing the aforementioned specific relationships as ´if-then´ rules combined with a set of common-sense rules. This paper presents the results of investigations into a new fault location technique using advanced signal processing technique based on wavelet technology to extract useful information and this is then applied to fuzzy logic in order to identify and locate the disturbances in a distribution system comprising of single core underground cables, through pattern recognition.