Grounding line selection method for small current system

The invention relates to a grounding line selection method for a small current system. The method comprises the following steps: establishing a power distribution network fault simulation model; solving wavelet singularity entropy of zero sequence current of each line; classifying the wavelet singularity entropy by using a support vector machine; judging a failed line. The wavelet singularity entropy and the support vector are used as a basis, and a fault line section algorithm is optimized to improve the accuracy of single-phase grounding fault line selection of the small current grounding system.