Adaptive non-communication protection scheme for power lines

This paper presents a new technique in power line protection, the "adaptive non-communication protection". In the proposed technique, the protective relay makes an instant or delayed tripping and reclosure operation decision adapting to the system and fault condition. The avoidance of communication links is achieved by detecting whether system is in a balanced operation or not to determine the breaker operation at the remote end of the protected line section, from which the location of the fault, inside or outside the protected line section, can be derived. The technique is simply referred to as "BO" protection. This paper presents the application of the combination of two main BO schemes for power line protection: (i) delayed operation scheme and (ii) instant operation scheme. An algorithm based on the symmetric components is proposed to detect and identify the balance condition of the system during the fault. Simulation studies of the scheme with respect to different system and fault condition are included in the paper and results show that the proposed technique and scheme is able to correctly discriminate between an internal and external faults while maintaining the operating speed, without the need for a communication link.