Abstract: Aiming at the compensation of the arc suppression coil of the coal mine power grid, when a single-phase ground fault occurs, there is a problem that the fault information is weak and it is difficult to distinguish. This paper presents a method for locating fault sections in coal mine power grids based on instantaneous positive sequence current characteristics. According to the characteristic that the current signal distance value of the transient positive sequence real part on the different side of the fault point is larger, and the signal distance value on the same side of the fault point is smaller, the signal distance value at the branch node is compared in turn, Corresponding to the fault branch, to determine the fault path, the fault signal has the largest signal distance value in each section on the fault path. A large number of simulations show that the positioning method can effectively distinguish the fault section under different fault conditions and has certain applicability.