Julio Gonzalez, left, Dr. Abdel Karrar, Mark Bowman and Andrew Adams stand with their IEEE Prize Paper award at the recent IEEE Power & Energy Society General Meeting. Photo credit: Kim Casteel Bowman.
A research collaboration between the University of Tennessee at Chattanooga and the Tennessee Valley Authority earned international recognition this summer from the Institute of Electrical and Electronics Engineers (IEEE), the world’s largest technical professional organization for advancing technology.
The UTC-TVA research team’s paper, “Offsite Power Grid Strength Determination for Nuclear Power Plants: Improved Calculations and Practical Implementation”—co-authored by Dr. Abdel Karrar, professor of electrical engineering and associate dean of the UTC College of Engineering and Computer Science; UTC undergraduate students Andrew Adams and Julio Gonzalez; and Mark Bowman, senior program manager of Power System Analysis at TVA—was selected as one of four Prize Conference Papers at the 2025 IEEE Power & Energy Society General Meeting (PES GM) in Austin, Texas.
Out of more than 1,600 papers submitted to the IEEE PES GM, considered the largest global forum for power engineers, only about 5% were chosen as Best Papers. From that elite group, four were selected as Prize Papers—one from each of the conference’s major technical tracks.
For Karrar and Bowman, the recognition in Austin marked a rare professional milestone: their second co-authored IEEE PES GM Prize Paper. Their first shared honor came at the 2016 conference in Boston.
“It’s one thing to have your work accepted to the IEEE Power & Energy Society General Meeting, but to be chosen as one of four prize papers in the world is an entirely different level,” said Karrar, a member of the UTC faculty since 2014. “This premier conference brings together practicing power engineers and academics from all over the world who teach and research power systems, and we went in and came out on top. We were ecstatic.”
The project stemmed from a long-running research partnership between UTC and TVA.
“This kind of research model really works,” Bowman said. “We collaborate on real problems with researchers and students. The result creates an ecosystem where innovation can happen.”
The research addressed a significant challenge in the nuclear power industry: how to measure the strength of the electrical grid—technically known as grid impedance—when real-time visibility is lost due to severe weather or emergency conditions.
As Karrar and Bowman explained, under normal operations, grid operators use supervisory control and data acquisition systems to provide nuclear power plants with continuous updates on grid health. If those systems fail or communications go down, power plant operators must still determine whether the grid is strong enough to safely supply offsite power during emergency shutdown or cooling events.
“Losing visibility of the grid is very concerning to a nuclear plant,” Bowman said. “Having a strong grid supply is so important to reactor safety that the nuclear plant must shut down until grid strength can be determined.”
The team developed a method for estimating grid strength based on localized measurements taken at the power plant itself. The approach used simulations of normal load fluctuations—“gentle nudges,” as Bowman described them—as a way to gauge whether the grid was capable of supporting critical safety loads.
The research was conducted using the College of Engineering and Computer Science’s Smart Grid Lab and its real-time digital simulator, which mimics the behavior of an actual nuclear power plant auxiliary power system under a variety of grid conditions.
“There are offline simulations that solve equations without time pressure,” Karrar said, “but in our lab, we use real-time simulation—meaning every second of simulated time corresponds to an actual second. It generates waveforms just like those in the real grid. That allows us to test real hardware in a loop with the simulation.”
TVA contributed equipment, software and testing support throughout the project. The simulator was initially developed to test and validate monitoring systems in advance of field implementation, but this project expanded its role to include the grid strength estimation model.
“Is this feasible? That was the question,” Bowman said. “Can we really estimate grid strength accurately from the plant’s point of view when upstream visibility is lost? The answer was yes. No one had ever tried this before and the conference saw something novel in that.”
For Gonzalez, a senior electrical engineering major graduating from UTC in December, participating in the project—and attending the IEEE PES GM in person—has quickly become an unforgettable experience.
“It was incredible. I would’ve never thought going into college I’d be a part of something that would be recognized nationally, if not internationally,” said Gonzalez, who grew up in northwest Georgia. “People from Hong Kong were there. Brazil. All the European countries.
“It is crazy to think that out of everyone in the world who submitted a paper, ours was chosen.”
Gonzalez helped build motor simulation models and processed data as part of the team’s test scenarios. He said he didn’t fully grasp the magnitude of the work until other industry professionals at the conference started congratulating the team.
“I was just excited to be chosen for the research in the first place. I didn’t even know what we were building would turn into something like this,” he said.
The recognition reaffirmed what Gonzalez had already learned at UTC. He didn’t have to leave Chattanooga to get a first-class engineering education.
“Have you ever watched the movie Monsters University?” Gonzalez asked with a laugh. “In the movie, the students all go to Monsters University because they want to work at Monsters Inc., which generates all of the power.
“As students, that’s kind of how we look at it: UTC is like a mini Monsters University and TVA is like Monsters Inc. generating power. We have world-class industry leaders right here locally. You don’t have to go across the world to get that kind of education.”
Adams, a senior electrical engineering major and a 2022 graduate of Chattanooga Christian School, joined Gonzalez in handling much of the project’s simulation work.
“The main part that Julio and I were working on was the simulation,” Adams said. “There was obviously a theory behind the work, but we weren’t sure if it was feasible.
“Julio and I were working in MATLAB and Simulink; it was the Watts Bar Nuclear Power Plant, fully simulated inside of Simulink. We ran different tests based on the theory to see if our method was feasible.”
When asked how he would explain the project to someone unfamiliar with power engineering, Adams pointed to an analogy Bowman had shared with him.
“It’s like trying to measure grains of sand on a springboard,” Adams said. “In order to shut down a nuclear plant, you have to have power—and if you don’t know if you have capable power, then your power plant is at risk.
“If I were to explain it to someone that doesn’t know about power, I’d probably say, ‘We’re just trying our best to keep the world safe.’”
Karrar said the success of the project reflects the broader strategy UTC’s College of Engineering and Computer Science has adopted to expose students to real-world engineering problems while building deep connections with industry partners.
“We’re always trying to get students excited about power systems,” he explained, “and this is one of the ways we do it. We bring real problems into the classroom and into the lab. We bring in professionals from TVA, EPB, General Electric and consulting firms to talk directly to students and show them how the knowledge they’re learning applies in the field.”
Bowman, who has worked in the nuclear power industry for more than 35 years, called the UTC partnership one of the most unique and valuable collaborations he’s been part of.
“There’s freedom in this kind of work. You’re not on a strict schedule with deliverables. You can brainstorm, throw ideas around and evolve something over time,” he said. “And when you finally get to present it and it gets recognized on a stage like this? It’s just fun and exciting. That’s what it’s like to work with UTC.”
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