Realization of Single-Phase Ground Fault Line Selection by Self-Adaptive Choice of Decomposition Scale in Distribution Network

When single-phase ground fault occurring in distribution network, decomposition scale in which each feeder modulus maximum locate has much difference, because of the complexity of transient component and the effect of system parameter and fault mode. Matrix M_ij of modulus maximum is constituted according to each scale maximum value after decomposing zero sequence current by Coiflet4 wavelet. If the modulus maximum of each line correspond the same scale, this scale will be identified as the characteristic scale. Otherwise the scale in which square sum of column vector element is maximal will be identified as the characteristic scale. For comparing of modulus maximum, the concept of ¿fault probability¿ is introduced and fault probability formula is defined. Practical criteria are given, which select fault line in digital quantification way. Self-adaptive choice of decomposition scale solves the problem of wrong judgment by reason of scale selection wrong due to complex transient component. Simulation experiments prove that this method is effective and credible.