An electric "supergrid" able to keep the power flowing in spite of multiple system faults could be demonstrated in New York City by the end of 2008. If the demonstration is successful, it will be deployed and commissioned by early 2010. The Dept. of Homeland Security is largely funding the project to strengthen the flexibility of large urban distribution networks.

DHS's Project Hydra will connect two area substations in Consolidated Edison Co. of New York Inc.'s midtown Manhattan grid with high-temperature superconducting (HTS) cable. Currently, power is fed from generation plants to a substation, where it is stepped down from 138 kV to 13 kV and delivered to customers in the distribution network. A fault current in a feeder, substation or distribution line can knock out power to the substation's entire network, as happened last summer in the city's borough of Queens.

The project will solve a problem of system design by interconnecting substations, says Steve Kurtz, Con Edison project manager. "The ability to interconnect substations allows you to put a transformer in either one of the substations and allows them to share it if they need it," he says. "The technology allows you to manage the fault current within the design capabilities of the equipment that's installed there."

HTS cables conduct electricity with negligible line loss via thin ceramic filaments embedded in a metallic matrix cooled with liquid nitrogen to virtually eliminate electrical resistance. "This is not only a superconducting cable. The fault-current limiter is integrated in it," says Jason Fredette, spokesman for American Superconductor Corp., Westborough, Mass. "It combines two very important products into one."

ASC signed a letter contract as prime contractor with DHS for Project Hydra on May 18. ASC is prime, and Con Edison will be ASC's subcontractor for the demonstration. DHS will fund up to $25 million of the total project cost, estimated at $39.3 million. Con Edison will fund $7.5 million, and ASC will provide the rest, says Kurtz.

The first phase, lasting 16 months, will involve laboratory demonstrations of the technology, aiming at a decision on deployment in August 2008. Under phase two, ASC would install 200 meters of 8-in.-dia "Triax" cable, which contains three phases of a circuit in one cable, and energize it by the first half of 2010.