Aiming at the problem that the topology of low-voltage distribution network is complex and leads to low fault segment localization accuracy

a fault segment localization method based on voltage difference network mapping and a posterior probability checking is proposed. Firstly

a reachable matrix is constructed to describe the topology of the distribution network to accurately reflect the connectivity of each node of the network; according to the change of the node voltage before and after the fault

the node fault voltage difference is calculated and clustered using the K-mean clustering algorithm to obtain the fault voltage difference matrix; the line segment state matrix is calculated by deducing the relationship between the reachable matrix and the fault voltage difference matrix. Finally

the Markov chain Monte Carlo (MCMC) algorithm is used to calculate the a posterior probability of faults in each segment

and the results of fault segment determination are checked. The results of several examples in distribution network show that the proposed method achieves a single fault recognition rate of 100% under different distribution network topologies. Under the same conditions

compared with the traditional methods

the convergence speed is increased by 40%

significantly improving the accuracy and reliability of fault segment localization.