Uhv Transmission Line Protection Principles Study

The UHV transmission line usually carries heavier power , it acts an important role to the security and stabilization of power system operation. The requirements of the protective relaying are stricter than ever. This paper summaries roundly about the development and current situation of UHV transmission line protection. Its specialty and requirements are also introduced. We mainly dress the following aspects of UHV transmission line protection theory:(1) Based on some of papers and books, introduced the basic theory of UHV transmission line protection, especially on current differential protection and its strongpoint and problems. At the same time, distance protection is introduced briefly.(2) Current transformer is a very important part of current differential protection. Introduced different types of TA, including their characteristics. Studied on the model and simulated the excitation curve of TA. Based of the research of the characteristic of TA saturation, the methods for TA saturation detecting and resisting are proposed.(3)Expatiated different kinds of restrain measures, and analyzed the operating characteristic, sensitivity and ability of resisting TA saturation of them. Some conclusions are gained after simulation by ATP-EMTP software.(4)Against of the problem of distance protection occurred in the reactive fault of transmission line, analyzed the operating characteristic of relay and proposed a method and practical solution. The relay is proved and some conclusions are gained after simulation.