A Creative Line Differential Protection Scheme for the Hudson River Crossing Section of a 345kV Transmission Line
Six 3-phase HPOF cables comprise the 1.3 mile Hudson River underwater section of NYPA’s 345kV RFK- 305 transmission line. The original protection, used to detect a fault in the cable portion, and to identify the actual faulted cable, consisted of 18 obsolete solid state differential relays, and these were replaced with six numerical line differential IEDs, utilizing the existing CT cable wiring as the communication medium. The six numerical IEDs provide the protection for the six cables, two per cable pair. A firm requirement was also the ability to identify not only the faulted cable pair, but the actual cable in which the fault had occurred, necessitating additional functionality to achieve this.