The first phase of testing has been completed for the Fault Current Limiter (FCL) II device, which was built under a U.S. Department of Energy (DOE) Superconductivity Partnership Initiative program for the design, fabrication and testing of a pre-commercial 15 kV-class superconducting current controller. The device incorporates three world record-sized high-temperature superconducting coils and was named the “Best Project” in the annual peer review of the DOE program. The project team was led by General Atomics, with Intermagnetics General Corp., DOE’s Los Alamos National Laboratory and Southern California Edison (SCE) as partners.
The fault current limiting function of the FCL II is designed to reduce fault current by 50 percent to 80 percent as required by the utility. In addition, while most existing electromechanical breakers operate only in 3 to 5 cycles, the FCL II can double as a 3/4-cycle (12-millisecond) opening switch. As a result, a system can be shut down before a fault becomes a problem.
“Our current controller concept combines cutting-edge power electronics and high-temperature superconducting (HTS) magnet technologies,” said Eddie Leung, General Atomics’ team leader and senior program manager. “It is one of several HTS power applications that should benefit the nation’s deregulated power industry significantly in the 21st century.”
Leung went on to say that the device’s main benefits for utilities are equipment upgrade deferral, power quality enhancement, system flexibility and reliability improvement. SCE manager Syed Ahmed said the current controller’s features will definitely help power utilities once the device proves to be reliable.
Embedded in the FCL II device are three huge HTS coils, each measuring more than 1 meter in diameter, 3/4 of a meter in height and weighing more than 1,500 pounds.
The compact power electronics subsystem, consisting of 96 thyristors, enables the Fault Current Limiter II to double as a sub-cycle fast opening switch for power utilities.