In the story of the three bears, Goldilocks repeatedly finds the happy medium that's "just right" — and researchers say there's a happy medium for electrical power grids as well. The problem is, their calculations suggest the U.S. power grid isn't just right.
In a study published online Tuesday by the journal Chaos, two physicists and an engineer say the nation's electrical distribution system would face a lower risk of severe outages if it were divided into scores of gridlets rather than the three major grids that exist today for the East, the West and a large chunk of Texas.
They came to that conclusion by building a computerized model that simulated the structure of the western U.S. grid. They found that bigger can be better: It's easier to transfer power between sections of the grid to even out variations in supply and demand, and respond if one part of the grid goes down.
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Researchers say the nation's three interconnected power grids may be larger than their optimal size.
But if the grid gets too big, the risk of a large-scale blackout cancels out the advantages — especially when the grid is running at close to capacity.
Such a blackout occurred in 2003, when a short circuit in Cleveland touched off outages affecting 50 million people in the northeast U.S. and parts of Ontario.
The Western grid has more than 16,000 electricity-converting nodes, which include generators, substations and transformers. In comparison, when the scientists subjected their simulated grid to a series of virtual outages, they found that the optimal grid size was just 500 to 700 nodes.
B.A. Carreras / BACV Solutions
The overall operational risk is plotted here as a function of the system size (N). The chart shows an initial reduction in risk as the system becomes more efficient with size, followed by an increase as the risk of large failures starts to dominate. The optimal size is the minimum point in the curve.
The researchers say that having a larger number of smaller grids would reduce the risk of cascading, catastrophic failures — and they suggest that the same right-sizing philosophy might apply to the Internet and financial markets as well.
"If we reduce the number of connected pieces, maybe we can reduce the societal cost of failures," University of Alaska physicist David Newman, one of the study's authors, said in a news release.
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In addition to Newman, the authors of "Does Size Matter?" include physicist Benjamin Carreras of BACV Solutions and Ian Dobson, an engineering professor at Iowa State University.
First published April 8 2014, 4:05 PM