by David Callis, Vice President of Statewide Services for the Tennessee Electric Cooperative Association
There are several misconceptions on what a “smart grid” is and the extent of its capabilities. One of the most troubling within our industry is the idea that our current grid is not already fairly intelligent in the way it operates. New technologies that are being deployed will greatly enhance the abilities of our current electric distribution network. But our existing network in the Tennessee Valley is reliable, durable and monitored around the clock by both man and machine. In particular, the high-voltage electric transmission system operated by the Tennessee Valley Authority is extremely reliable.
TVA balances generation and delivery and deals with challenges of weather extremes and unexpected emergencies. Add to those challenges maintaining interconnections with 13 neighboring utilities, providing power to a number of large, directly served customers and keeping 15,900 miles of transmission lines in service.
How good of a job does TVA do? Every year since 2000, it has achieved a transmission reliability rating of 99.999 percent. Just as your co-op’s goal is make sure that your lights come on when you flip the switch, TVA operates the transmission system with one goal: providing a stable power supply to the 155 distributors throughout the Valley.
Residents of southern California would certainly like to have our level of reliability. During the second week of September, a cascading failure in the independently operated transmission grid caused power outages that affected, by some estimates, 6 million people.
The culprit? A transmission path called the Southwest Power Link. The Wall Street Journal reports:
“Something happened at approximately 3:30 p.m. Pacific time to cut off the flow of power through the North Gila substation, triggering the disturbance. ‘It looks like operator error caused a short-circuit on a heavily loaded line,’ said Michael Niggli, president of San Diego Gas & Electric.
“A spokesman for Arizona Public Service said it is premature to pin blame on workers, saying it still wasn’t clear exactly what happened. But in a news release Thursday, the utility said the outage ‘appears to be related to a procedure an APS employee was carrying out at the North Gila substation.’”
We depend, rightly so, on hardware and software that make millions of decisions per second. Equipment is constantly checking and rechecking for problems that arise on the power grid.
What is too often overlooked in the smart grid conversation is the role played by the most technically complex component found at all utilities — humans
Skilled workers monitor the generation and flow of every kilowatt-hour that travels through the TVA transmission grid. The control center is in a protected, secure location and staffed 24 hours per day. A backup center is also available should some catastrophe occur. Many of Tennessee’s larger cooperatives have similar types of centers for their distribution systems.
TVA’s transmission crews and operators demonstrated their abilities by returning power to most areas within seven days following that destructive April outbreak of tornadoes across the Southeast. The storms caused unprecedented damage to the transmission system that delivers power to your local distributor’s substations.
“Immediately following the tornadoes we identified the lines that could be fixed quickly and restored power to customers using these lines,” said Rob Manning, TVA executive vice president of power system operations. “In a week’s time, 95 percent of the affected customer connection points were reconnected, yet only about a quarter of the structures were repaired. After a month, 102 lines were back in service.”
In the next month and a half, TVA’s employees and contractors continued the work, rebuilding 108 transmission lines and 375 steel structures, using 235 miles of wire and 1.4 million pounds of steel. What nature tore down overnight had taken literally years to build. Putting it back up took 74 days.
While we can’t say that what happened in California could never happen here, we’re confident in the technology and equipment, human and mechanical, that run the transmission and distribution network in the Tennessee Valley — a partnership of TVA and your local cooperative.
A slogan used by the Kentucky Association of Electric Cooperatives probably says it best: “Our Power is our People.”
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