Application of distance protection in mixed overhead-underground distribution feeders with distributed generation

摘要

This study applies distance protection to real mixed overhead-underground distribution feeders, as an alternative to conventional overcurrent protection schemes. The efficiency of the proposed distance-based protection scheme is examined both in the radial (normal state) and in the looped operation of the distribution feeders. Moreover, distributed generating units of various types are assumed connected to the feeders to investigate their effect on the efficiency of the protection scheme. The latter proved sufficient to coordinate properly with the other protection means in the system, following a fuse-blowing philosophy, providing reliable protection to the lines.