The traditional single line-to-ground fault phase selection method for distribution network generally ignores the influence of the parameter asymmetry. When the transition resistance is large enough, it will cause the wrong selection of the fault phase and result in a phase-to-phase short circuit. By measuring the neutral point voltage to divide the coordinate system, a new fault phase selection method is proposed. The proposed method has strong adaptability to the transition resistance and the asymmetry of the three phase parameters of the distribution network. The fault phase can be correctly selected under various neutral grounding modes. Simulations in MATLAB/Simulink verify the effectiveness of the method.

single phase-to-ground fault; fault phase selection; parameter asymmetry; voltage trajectory