NEW YORK, August 1, 2012 — In terms of number of people affected, the largest power grid failure in history occurred in India this week, and it raises a question for America: Is the U.S power grid susceptible to a nationwide collapse?

To answer that question, we must understand the layout of the North American power grid. It is divided into four regional power systems, called interconnections, as depicted in the main picture above. On the west coast there is the Western interconnection. On the east coast, you guessed it, the Eastern interconnection, as well as the Quebec interconnection. The last is the ERCOT interconnection (the Electric Reliability Council of Texas). Texans always seem to do things their way, and electricity is no different. They chose to operate differently than the rest of the grid, and that decision has been both an asset and a liability. But that is another story.

These three main interconnections (Western, Eastern and ERCOT) are electrically isolated from each other. They are electrical “islands,” with no wires making connections between each region. If the Western Interconnection were to blackout, it would not have an impact on the ERCOT or Eastern interconnections. If ERCOT were to go dark, only the Texans would complain. The Eastern interconnection has had its share of difficulties over the last 60 years because it is so highly interconnected (this explains why the Eastern interconnection system frequency was affected by the loss of transmission lines in Florida), but again, there is no tie operationally and its operations do not affect the Western or ERCOT interconnections. This inherent isolation is the saving grace of our power network, but it was born that way out of logistical hurdles, not ingenious forethought. Crossing the north-south running Rocky Mountains with east-west transmission lines would prove too costly to build and maintain in the long run, creating a “natural” segregation in the power grid.

Outside of the isolation of the regions, the U.S. has plenty of generating capacity online, and plenty of capability on standby called “operating reserves.” The grid operators have a reserve margin calculation and keep approximately 14 to 17 percent of the forecasted peak load available as generation on standby, in case a large transmission line or a large generator unexpectedly shuts down, or “trips.” Grid operators look at these large facilities and model them in their networks as contingencies that must be taken into consideration at all times. They must know how the system would react if a tornado took down a large transmission tower that was delivering massive amounts of power, or knocked a large generating station, like Indian Point Energy Center, offline. 

It will take some time to discover the cause of the blackouts in India, just as it did to discover the cause of the August 2003 blackout which rendered much the northeast powerless. Some blackouts are necessary to avoid equipment failure, and some can be prevented by proper communication and operations. As a result of the August 2003 blackout that left some 50 million Americans without power, the National Electric Reliability Corporation mandated that companies follow reliability protocols that were, up until the blackout, voluntary.  

If the entire U.S. were to go dark, it would not be the result of regional connectivity, or cascading interconnection issues. All three interconnections, along with Quebec would have to suffer a catastrophic failure simultaneously. Could it happen? Yes, anything is possible. Is it likely to happen? No, not likely at all.

 

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