Relay protection operation for faults on Nysegʹs six-phase transmission line

This paper describes the performance of the protection system used for the first commercially operated six - phase transmission line in the world - New York State Electric & Gasʹs 93 kV (phase to phase and phase to ground) line from Goudey Station to Oakdale Substation during faults in the winter of 1993. The paper briefly describes the basics of the High - Phase Order Transmission Demonstration Project and the integration of available state of the art microprocessor based relays, with a programmable logic relay (designed for the protection of conventional three-phase systems) in a hierarchical six-phase protection system. The operation of the protection system during two faults on the line in January and February 1993 is reported. The modeling of the six-phase line in a conventional three-phase short circuit study program is also considered and a comparison between the measured and calculated fault currents is presented. The project was sponsored by Electric Power Research Institute (EPRI), the Department of Energy (DOE), Empire State Electric Energy Research Corporation (ESEERCO), New York State Energy Office (SEO), New York State Energy Research and Development Authority (NYSERDA) and New York State Electric & Gas Corp. (NYSEG).