ABSTRACT
Transmission lines are the backbone of power systems. Short transmission lines may be less than one mile long. Long transmission lines may be hundreds of miles long. Transmission systems are designed with sufficient redundancy to tolerate single failures. Even so, with generating stations located in rural areas and load centers in urban areas, system stability (resilience to fault-induced grid collapse) is a major concern. When the need for redundancy and stability considerations are addressed, the result is that transmission-line protection is more complex than distribution-line protection.
