Implementation of Quasi-Real-Time Rating Software to Monitor 525 kV Cable Systems

In 1999, BC Hydro installed optical fibers in the fluid channel of 525 kV self-contained fluid-filled submarine cables originally installed in the 1980s that connect substations in the Vancouver area of British Columbia, Canada, for the purposes of monitoring temperatures. In combination with this work, a real-time monitoring was used to collect load data and measured temperatures in an effort to optimize the ratings of the cables. The dynamic thermal circuit rating system developed by the Electric Power Research Institute was applied to the 525 kV cables as part of a project to modify the system for support of the unique characteristics of the cable system installation. Specifically, the submarine cables utilize a parallel pipe water cooling system for the shore zones. This paper describes the software modifications that were implemented to enhance the dynamic rating system to model the unique characteristics of the 525 kV cable system and discusses how recorded data collected over several seasons were used to verify and refine the cable rating model. The resulting evaluation showed good agreement of the dynamic rating system calculations with measured results and helped the utility better understand the ratings on these circuits and permitted the utility to perform simulations to evaluate various loading conditions.