The waveforms of the current fault component of two phases are symmetrical according to an analysis of wrong-phase-coupling. This characteristic can be quickly extracted by correlation analysis. Based on the characteristic of the power traction system， a new protection scheme is developed by referring to the correlation analysis of the fault component. The MATLAB simulation results and the analysis of actual data on a short circuit fault show that， with its good discernment， this protection scheme can be equipped in the protection system of the traction power substation.