Operational characteristics of a 1000 MVA superconducting power transmission system

Over the last three years, the power transmission project at Brookhaven National Laboratory has been testing two flexible superconducting cables for the transmission of ac electric power. These cables are each 115 m long and are rated at 80 kV, 4100 A single-phase for a power rating of 333 MVA- (1000 MVA, 138 kV, 3 phase). They have been operated over the range of 7-12 K in supercritical helium at 14-15 atm. The cables have been tested at currents and voltages above their ratings and have also been operated with no coolant flow to study the effects of loss of refrigeration on cable performance. The insights gained from the operating of the system over this extended period will be presented. Finally, we will delineate those areas which will require further research before this technology can be integrated into the U.S. electrical power delivery system.