Fault Line Selection Method for Single Phase Earth Fault Based on Transient Signals in the Frequency Band

A novel approach in distribution protection technique of fault line selection is presented based on transient signals detected with the wavelet transform maximal module in this paper. The characteristic frequency band of each line, in which the maximal module is most concentrated, is chosen according to the view of maximum energy. For each case that the characteristic frequency band of each line lies in or out a same one, two types of numerical fault detecting criteria are proposed. The proposed method overcomes the blindness in determining the feasible frequency band that conventional methods cannot avoid. The effectiveness and practicality of the method proposed are demonstrated via field test results.