Self-Synchronized Current Differential Protection Scheme for Transmission Line

Current differential protection is simple and reliable in principle. But it has a strict requirement for data synchronization, and mal-operation will happen for a large synchronization error. Aiming at common criterion used in line current differential protection, this paper analyzed its ability against synchronization error for internal and external faults firstly. Then refer to fault occurring time, self-synchronized scheme was put forward for transmission line current differential protection. Meanwhile its error sources, feasibility and application conditions were analyzed and demonstrated in detail. After that, using on-site recorded fault data and simulation data, the paper verified the viability of this scheme. Principle investigation and simulations indicate that the proposed scheme can get rid of the dependence on synchronous clock, and be free of the influence of transmission delay and routing change of multiplex channel. Under current technology condition, this scheme's synchronization error is in the allowable range. Therefore it can be a new choice for realization of line current differential protection. © 2019, Electrical Technology Press Co. Ltd. All right reserved.