Circuit inter-phase fault single-end ranging method

The invention discloses a circuit inter-phase fault single-end ranging method, which comprises the following steps of: measuring a fault inter-phase voltage phasor, a fault inter-phase current phasor and a fault inter-phase negative sequence current phasor serving as input quantities of a circuit at a transformer substation protection installation position; calculating the voltage phasor at a fault position by using protection measured electric quantity; sequentially calculating matching error data of each point on the circuit by gradual step length increment from the beginning end of the protected circuit till a setting range of emitting a trip signal; if the protective trip signal cannot be acquired, searching the overall length of the protected circuit; and taking the point corresponding to the minimum matching error datum value as a fault point, wherein the distance between the point and the circuit protection installation position is a fault distance. The method is not affected by distributed capacitors, load current, fault resistors and operation mode of a system, has no false root problem of solving an equation or non-convergence problem of an iteration method, and has strong practical value.