Operation evaluation of DWT-based earth fault detection in unearthed MV networks

A novel selectivity technique to estimate the faulty feeder in MV networks was introduced in [1]. This technique depended on the directionality of discrete wavelet transform (DWT) detail coefficient of a residual current of each feeder with respect to the DWT detail coefficient of the residual voltage. The algorithm efficacy has been examined with high impedance arcing fault due to leaning trees. In this paper, the algorithm performance is tested with resistance earth faults over a wide range of the fault resistance values (1 mOmega to 100 kOmega) as well as concerning practical fault cases such as arcing faults. The fault cases occurring at different locations in an unearthed 20 kV network are simulated by ATP/EMTP. Test cases confirm the efficacy of the proposed technique.