Electric power line distance III-section protection misoperation hidden danger eliminating method and device

The invention discloses an electric power line distance III-section protection misoperation hidden danger eliminating method and device. The electric power line distance III-section protection misoperation hidden danger eliminating method comprises the following steps that phase-to-phase distance III-section protection or ground distance III-section protection enters start-up logic; whether an unsymmetrical fault occurs is judged according to the electrical characteristics of an electric power line, trip of the ground distance III-section protection directly happens when the unsymmetrical fault occurs; trip of the phase-to-phase distance III-section protection directly happens when a symmetrical fault occurs; the electric power line is judged to be overloaded, the phase-to-phase distance III-section protection or the ground distance III-section protection is blocked, and misoperation of the phase-to-phase distance III-section protection or the ground distance III-section protection is avoided when the symmetrical fault occurs. According to the electric power line distance III-section protection misoperation hidden danger eliminating method and device, trip of the phase-to-phase distance III-section protection or the ground distance III-section protection happens when the unsymmetrical fault or the symmetrical fault occurs and the phase-to-phase distance III-section protection or the ground distance III-section protection can be blocked and misoperation of the phase-to-phase distance III-section protection or the ground distance III-section protection can be avoided when the electricity power line overloads.