Fast and Selective Protection Technology in Low Voltage Distribution Systems

Because of the limited information interaction between protective electrical apparatuses in different distribution levels, rapidity and global selectivity are difficult to achieve concurrently in short-circuit fault protection. Based on short-circuit fault early detection, a fast and selective protection technology in low voltage distribution systems was presented, in which the effective interaction of short-circuit fault information between fault detection modules and central control module could be achieved through CAN bus communication. The overall protection scheme was illustrated, then short-circuit fault early detection method and its key role in fast and selective protection was analyzed, and the flexible and reliable selective protection mechanism based on CAN bus was designed. Finally the scheme was applied in simulated short-circuit fault selective protection experiments to test the completion time of selective protection and observe detailed interaction processes. The results show that the selective protection technology combining fault early detection and CAN bus communication can find the fault level fast and accurately, and give a breaking command to the relevant protective electrical apparatus reliably, which contributes to the fast and global selective protection in low voltage distribution systems.