Application And Study Of Optical Fiber Current Differential Protection In HV Power Grid

With the rapid development of the grid and power digital communication network, optical-based digital differential current protection has been the ideal choice for acting main protection of transmission lines because of its good performances. But there are some practical problems in operation, such as TA saturation,TA line-break,sampling synchronization of both sides of the protection devices, which can cause incorrect tripping and blocking of protection.Two practical problems of optical-based digital differential current protection have been raised in this paper. Some improvements have been introduced to the traditional criterion of differential current protection in order to provide a solution to TA saturation problem of weak feed transmission lines when it is introduced to them. Because the cost of synchronous devices of optical current differential protection is high, a simple low-cost synchronous method-synchronous method based on fault signal has been proposed in this paper. Simulation results show that the proposed method can meet synchronization requirements of differential protection presented in this paper.