Adaptive non-communication protection for power lines BO scheme 1-The delayed operation approach

This paper proposes a new technique in power line protection, the "adaptive non-communication protection". In this technique, protection relays make operate or restraint decisions, adapting to system and fault conditions, without the need for communication links. Operation without communication links to signal the remote end relay is achieved by the detection and identification of the operation of the circuit breaker at the remote end of the protected line section. An algorithm based on symmetric components is proposed to detect and identify the balance condition of the power system during the fault. The paper is focused on one of the three protection schemes based on the new technique, the delayed operation scheme. Simulation studies carried out for various power systems and fault conditions have demonstrated its feasibility