Study Of The New Fiber Differential Protection Principle And Device

High voltage transmission lines have a greater probability and variety of fault than any other components in power system. Nowadays microprocessor has been widely used in relay protection, differential protection has been the primary choice for the main protection of transmission lines and others, surpassing other choices of relaying with its obvious natural characters. This dissertation discusses the principles of differential protection and synchronized sampling and several special issues in details. A digital protection device based on them is developed. Considering the principle of protection, the development and several special issues of the protection for extra high voltage(EHV) transmission lines and the principles and character of differential protection based fiber are studied at the beginning of the dissertation; several traditional principles of differential protection are introduced, analyzed and compared in the following section; adaptive protection applied in power system has been also introduced, then a new adaptive differential protection is studied, and tested with Electromagnetic Transients Program (EMTP) modeling. Considering synchronized sampling, several traditional ways of synchronized sampling are discussed, analyzed and compared in the following section. Considering practice and character of the protection system, a amendatory synchronized way based on adjusting sampling time is used. Considering the development of the protection device, the design of a digital differential relay of based Digital Signal Controller (DSC) for EHV transmission line is introduced, the design of hardware, the configuration of protection functions, fiber communication, disturbance mitigation and special problem are presented in detail.