Wisconsin Public Service (WPS) has been shoring up its grid using a distributed superconducting magnetic energy storage (D-SMES) system, which contains six individual SMES units that WPS is installing at five different substation locations. They’re looking to improve reliability and capacity at geographic locations with voltage stability problems. SMES is a short-term solution, a temporary fix until WPS can get a new high-voltage transmission line connected to the area. While WPS has a three-year projection for the SMES units, they could be used longer, if construction or regulation issues arise.
Larry Borgard, vice president of transmission and engineering, said things are going very well. He heralded the system’s portability, which allows WPS to shift the SMES units, if necessary, in order to cover problems created by storms or other disasters–not simply overloaded grids. So, in the end, Wisconsin’s SMES use depends almost entirely on the unpredictable.
“They just sit there in a stand-by mode until such time as they’re called upon–like during lightning storms, things like that. It isn’t a situation where they’re active in the grid 24 hours a day; they really require some event to trigger them, to charge the system with both real and reactive energy. So, it all depends on how many lightning strikes we get,” he said.
Borgard stated that WPS had compared a number of different systems, both traditional (converting a lower voltage transmission line to a higher voltage) and nontraditional (static bar compensation), and found that the D-SMES offered by American Superconductor provided the best of both monetary considerations and quality.
“The performance [of D-SMES] is superior to the other things that we looked at, and, ultimately, the economics turned out to be superior as well,” Borgard commented.
Wisconsin Public Service is deploying the D-SMES system in its northern transmission loop, a network approximately 200 miles in circumference that is located in the Wausau and Eagle River areas of Wisconsin.