Abstract:Starting from the power supply and distribution power flow and the configuration of the relay protection device, combined with the fault cases in the actual operation of the power supply and distribution system, check the protection value and protection time limit in the power supply flow, and adjust some inconsistent lines in the power flow. The relay protection action level is poor, and the risk of the leap-level action is eliminated. The action logic and alarm logic of the line SEL protection device are analyzed, and the zerosequence over-current and phase-to-phase over-current protection early warning logic is added to realize the early warning function during the fault, and the reliability and fault location capability of the power supply side relay protection are improved.