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Powell Valley Electric Cooperative may have just dodged a weather bullet by implementing a plan to conserve energy in 15-minute increments during the recent unprecedented cold snap. The ‘rolling blackout” likely saved the power grid and the people served from prolonged and widespread outages.

The Tennessee Valley Authority (TVA) mandated that its local power companies use the plan in short spurts to offset electric consumption.

The plan reportedly did the job in and around Claiborne County as PVEC reports lower than normal “regular” outages during the Dec. 22-25 period.

Brad Coppock, PVEC General Manager, said during an interview that some 2,000 megawatts – equal to a nuclear plant – were “shed” off TVA’s power load because of the willingness of the 153 local power companies to use the rolling blackouts.

Coppock said the frigid temperatures presented the opportunity to use the idea which, although included in TVA’s Emergency Load Curtailment Plan, had not until now been necessary. The plan had just been updated the first of December.

Coppock described what would occur if TVA were to call for the activation of specific steps detailed in the plan.

“TVA might call for a ‘step 10’ which means they’re asking the utilities to turn off any non-essential lines and to turn thermostats down in all utility-owned buildings.”

A “Step 20” could involve local power companies requesting its member customers to conserve energy by curtailing the use of dishwashers, washers, dryers and other high-energy consuming appliances. Customers would also be asked to adjust thermostats upward or downward depending on the time of year.

“Those two steps are not all that uncommon. When you get into steps 30 and 40 that gets into voltage reduction. Through our computer system, we can lower the voltage at our substations. That conserves the energy somewhat without it really affecting the consumers.”

Coppock says a call to implement Step 40 involves appealing to the largest customers to reduce the use of heating and cooling.

“I’ve been here for 21 years, and that’s the first time I’ve ever been involved in Step 40. Step 50 is rolling blackouts. Never in TVA’s history – and they’ve been around for nearly 90 years – have they called for rolling blackouts,” said Coppock.

The utility company uses a Supervisory Control and Dated Acquisitions System that allows PVEC to control breakers throughout its coverage area. This system allowed the rolling blackouts for a limited time on Dec. 23 into the morning of Dec. 24.

Coppock says the manufactured blackouts ran for just 15 minutes and, in most cases, rotated through just the one time. Those who experienced more than one manufactured blackout, he said, can attribute it to TVA’s upping the percentage of power needed to be “shed”, particularly on Christmas Eve.

“If the blackout lasted more than 15 minutes, it was an outage. I can attest that our (PVEC) blackouts lasted just 15 minutes because I was the one that was pushing the button.”

According to Coppock, about 30,000 meters were affected. Hospitals and other emergency agencies were exempted.

“Whatever the system load is, let’s say it’s 100 megawatts, TVA would say ‘we need you to reduce five percent of your load.’ Using this just as an example, Powell Valley would need to shed five megawatts off our system for 15 minutes.

“We looked at the devices that had that type of load going through them. Say, we picked one in Harrogate that had five megawatts going through it and we cut it off. Right before the 15 minutes was over, I’d pick one in Virginia. I would cut it off then I would cut the one in Harrogate back on. Then, before the 15 minutes was over, I’d pick one in Tazewell. This would continue on with my keeping a record of it,” said Coppock.

He compared loads experienced during this latest cold spell to frigid temperatures in the past.

“We haven’t had an event like this since 2014-15. We had the polar vortex and then, in 2015 we had some extremely cold weather – I think minus five or minus ten, in February. That was our all-time peak at 207 megawatts. What just happened here, I’m certain would have surpassed that if our industrial customers had been working and the schools had been open,” said Coppock.

During the latest cold snap, power usage reached its peak of 191 megawatts on Christmas Eve night, he said.

Residential homes affected by a true outage were, for the most part, due to the tripping of transformers during the extreme cold. A few occurred during the overnight hours of Dec. 22-23. Coppock attributes the lowered number of true outages to “constant improvements” and “staying vigilant.”

He said he is extremely proud of every employee.

“My hat’s especially off to the linemen. It takes a special person to do what they do – to be on call, leave their homes and families to face all kinds of weather. During the coldest part of the event, I made the rounds taking breakfast biscuits for the crews on the job. I was at one location and got to talking with a couple of the men in the bucket. I noticed one had ice forming in his mustache and the other in his beard.”

The Tennessee Valley Authority says it is using this event as a learning experience, reviewing the “what and why” and sharing with the public the lessons learned along with the subsequent corrective actions.

“We at TVA take full responsibility for the impact we had on our customers. This is not the way we want to serve our communities and customers,” reads a news release, in part.