A backup protection approach for multisection compound transmission lines

This paper proposes a backup protection technique for two-terminal compound untransposed transmission lines using synchronized phasor measurement units. The proposed technique can be applied for single or double circuit transmission lines considering the mutual coupling between the sequence circuits and adjacent circuits. Voltages and currents phasors in the phase domain at both ends of the transmission line are used for detection, location and classification of transmission line faults. The proposed technique has the ability to distinguish internal faults of transmission lines form others external faults or load change conditions and to determine the faulty line section and fault type, as well as the fault location. The technique considers the randomness of faults on transmission lines, measurement errors, different fault inception angles and fault resistances, as well as different fault types. Extensive electromagnetic transient simulation studies implemented using MATLAB software demonstrate that the proposed protection scheme can detect, classify and locate all transmission line faults precisely.