Research On Fiber-optical Single-phased Current Differential Protection

With the rapid development of the power system, the power grid changes day to day, such as: the number of parallel lines increases greatly, the transmission lines become much longer and the load is much more heavy. Furthermore, T lines and the multi-terminal lines are commonly used. The traditional protections, including the Phase Differential Protection Based on High Frequency, the Directional Protection Based on High Frequency and the Distance Protection cannot meet the demand of these developments.The thesis is focus on the research of the optical-fiber differential current protection that can adapt to the rapidly changing power grid. It mainly contains the following four parts: (1) Theoretical analysis of some operation criterions and some factors that influence the operation of the differential protection. (2) Simulation of a 500kv transmission line using EMTP software. The results were visually analyzed through Matlab software at length. (3) Analysis and comparison of some synchronization methods used by domestic and abroad companies. (4) Programming the software of the protection devices and having dynamical tested the devices.The devices have many merits. They can sensitively and reliably cut off all the faults occurring in the power system. Even under the critical situation, faulting on the long heavy load transmission lines through high ground resistances, the criterion based on fault components still has considerable sensibility. Wang Xiaoyu (Power System & It's Automation)...