Washington, August 17 : A theory that may help build future superconducting alternating-current fault-current limiters for electricity transmission and distribution systems has been developed, thanks to the efforts of a physicist at the U.S. Department of Energy's Ames Laboratory.
John R. Clem says that he has basically identified design strategies that can reduce costs and improve efficiency in a bifilar fault-current limiter, a new and promising type of superconducting fault-current limiter.
Just like household surge protectors that save equipment like televisions and computers from damage during a lightning strike, fault-current limiters protect power grids from sudden spikes in power.
During the study, Clem analysed a type of fault-current limiter, called a bifilar fault-current limiter, developed by Siemens and American Superconductor Corporation.
"I was able to theoretically confirm that planned design changes to the current bifilar fault-current limiter being developed by Siemens and American Superconductor would decrease AC losses in the system. My calculations are good news for the future of the device," he said.
"I modelled the bifilar design as an infinite stack of superconducting tapes, in which adjacent tapes carry current in opposite directions. I was able to find an exact solution for the magnetic fields and currents that are generated in such a stack of tapes.
Once I calculated how the magnetic flux penetrates into the tape, I then could calculate how much energy is lost in each current cycle for different tape widths and spacings between adjacent tapes," the researcher added.
A research article describing this work has been published in a recent issue of Physical Review B.