Modern trends in line and network protection systems

This paper presents the impact of exploding developments in communication technology on protection systems, especially as applied to line and network protection. Classical line distance protection systems exhibit problems in handling special application cases such as: high impedance grounded systems; high impedance faults; cable protection; short lines; series compensated lines; presence of distributed generation; multiterminal lines; etc. Current only, longitudinal protection systems such as current differential and phase comparison systems solve these application problems simply and elegantly. The deregulation of the energy market forces the owners to operate the system close to network capacity limits, the system stability and wide area protection issues become paramount. Existing and emerging communication technologies provide dependability, low cost and omnipresence of data links needed to operate these systems.