Adaptive non-communication protection for power lines BO scheme3-The accelerated operation approach

摘要

This paper presents the accelerated operation scheme of thenadaptive noncommunication protection technique for power lines withncomplex configurations, such as multi-end feeders and ring mains. In thenscheme, the overcurrent directional relays are arranged in two operatingnmodes, the fixed time operation and accelerated operation. The relaysnwith faster operating time in the conventional time grading coordinationnremain unchanged. The new technique is employed to enable acceleratednoperation to be achieved for the relays which are in the positions fornwhich slow operating time is set when using conventional time gradingntechnique. For a fault occurring on the protected system, the relays ofnfixed time operation mode will operate at the preset time for the faultnwithin its protected direction. The relays which are programmed to usenaccelerated operation mode will determine whether a fault is on thenprotected section or not by using the BO technique, that is to detectnthe circuit breaker operation by determining whether the line section isnin a balanced operation condition or not. The relay makes acceleratedntripping decisions for a fault on its protected section. Simulationnstudies of the responses to various system and fault conditions shownthat the scheme can significantly increase the speed of the relaynresponses in the protection of power line systems with complexnconfigurations