February 1, 2009

HTS Cables Speed up the Electric Superhighway

Angela Neville, JD

From the Lab to the Real World

U.S. commercial power grids are beginning to use the new HTS power transmission cable system.

"HTS cables have been well demonstrated at electric utilities and are now being deployed in the grid," McCall said. "Over the past two years, three HTS cables have been energized in the U.S. Today HTS cables by Southwire carry up to 3,000 amps at 13.2 kV in the grid that American Electric Power manages in Columbus, Ohio. National Grid energized a distribution voltage HTS power cable system by Sumitomo Electric in Albany, N.Y., in the summer of 2006. Other cables have been energized by LS Cable and KEPRI in Korea and Innopower and Changtong Cable in China."

In April 2008, LIPA installed and energized the world’s first HTS power transmission cable system in a commercial power grid, he added. The Nexans 138-kV cable system installed in LIPA’s grid runs nearly a half mile in length and is the longest and most powerful HTS cable system to date (Figure 3).

3. Lighting Long Island. This photo shows the first cable phase being pulled through a conduit in Long Island Power Authority’s Holbrook transmission right of way. Courtesy: American Superconductor Corp.

At 574 MW, the LIPA cable system is able to serve 300,000 residents and businesses in New York’s Nassau and Suffolk Counties. The 138-kV system, which consists of three individual HTS power cable phases running in parallel, was commissioned in April 2008 and is operating successfully in LIPA’s Holbrook transmission right of way (Figure 4).

4. Power pioneer. The world’s first HTS power transmission cable system energizes the Long Island Power Authority’s Holbrook transmission right of way. This system, which consists of three cables running in parallel in a 4-foot-wide underground right of way, is capable of carrying 574 MW. The three cables shown entering the ground can carry as much power as all of the overhead lines on the far left. Courtesy: American Superconductor Corp.

According to McCall, Con Ed in New York City is in the process of installing a 4,000-amp, [correction: 13.8-kV] fault current limiting HTS cable in downtown Manhattan, and Entergy is in the early engineering stages of installing a 2,000-amp, [correction: 13.8-kV] cable in the New Orleans area.