The Research On Reliable Coefficient And The Least Protection Zone Of Distance Protection Ⅰ

Traditional setting for distance relaying I can't work efficiently with the developments of relay protection and constructions of the electric power system. The changes of the grid, the developments of the microcomputer and the more rigid requirements for distance relay have made the setting of distance protection I faced the new challenge. In this paper, thorough analyses about the factors, which affect the setting, are made in order to get the conclusions, which can be references to the actual setting. Recording to the conclusions, the protection zone varied with different system resistance and line length, both for single phase grounding distance relaying and inter-phase distance relaying. It gives the least protection zone for each example after the analyses. In the end, the adaptive technology is learned and will be used in the setting of reliable coefficient in distance relay.