American Superconductor (AMSC) and the Tennessee Valley Authority (TVA), the largest public power provider in the U.S., have announced the start of production of two 12 megaVAR (MVAR) SuperVAR dynamic synchronous condensers.  When the first of these machines ships the first of the two machines in late 2006, the superconductor community will at last be able to point to a high temperature superconductor (HTS) device installed as part of a permanent electrical power system.

The SuperVAR is designed to stabilize grid voltages and increase service reliability, and can help maximize transmission capacity.  The device, which is effectively a superconducting electric motor designed to provide reactive power (VARs) to a power grid, is one of several tools in the toolbox of flexible AC transmission system (FACTS) technologies.  FACTS is seen by engineers as key to meeting electric power delivery, reliability, and quality requirements for the nation’s aging grid.  They are also seen as essential tools for integrating distributed and renewable energy generation into power systems.  

TVA’s decision to take on the 12MVAR machines follows extensive testing of the prototype DSC on a 13.8kilovolt circuit serving a 50MVA steel mill operated by the Hoeganaes Corporation.  Since it was first synchronized with the grid in January 2005, the device has reportedly operated successfully through over five million voltage sags and surges.

While propriety between partners can sometimes obscure a darker truth, it appears that Hoeganaes was a solid success, technically speaking, and that the additional devices were indeed not ordered as further proof technology and functionality.  Mike Ingram, Senior Manager of Transmission Technologies at TVA told Superconductor Week the devices on order “will solve a real problem on our system.”  

At 12MVAR, the two systems commissioned by TVA will each be rated 33% higher than the 8MVAR prototype, and will include a number of technology and engineering improvements.  With commercial applications typically calling for systems in the 50 to 150MVAR range, the 12MVAR DSCs will still be far smaller than the large-scale devices sought for most commercial applications.  

Scaling these machines to larger power ratings will likely involve real technical challenges, and whether the commercial rewards to such risks are worthwhile remains to be seen.  However, in addition to reaching a broader market, AMSC expects larger machines to cost less in terms of cost per kVAR, making them more competitive with other solutions such as STATCOM.  

With luck, the SuperVAR could provide AMSC with a real commercial (rather than R&D) driver for HTS wire demand, helping to generate the long-awaited economies of scale that could bring HTS wire costs closer to targets set by the DOE and others.  We covered some cost and technical details in Superconductor Week issue 2002, and provide an analysis in a forthcoming issue of how the SuperVAR fits in terms of functionality and economics within the FACTS market.  Regarding FACTS in general, one expert was unambiguous about the future: “The market will grow, and trends both in energy generation and in consumption will push that growth.”

Mark Bitterman, Executive Editor, Superconductor Week
http://www.superconductorweek.com