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August 2, 2022

Twenty years ago, the power grid was run mostly on fossil fuels and nuclear power. Vijay Vittal, a Regents Professor of electrical engineering in the Ira A. Fulton Schools of Engineering at Arizona State University, was an influential voice in power grid research during that time.

Working with other electrical engineers, he defined stability criteria for the power grid as it existed in 2004. Along with his co-authors, Vijay Vittal, a Regents Professor in the Ira A. Fulton Schools of Engineering at Arizona State University, won the 2022 IEEE PES Prize Paper Award for his contribution to redefining power grid stability. Photo courtesy Shutterstock Download Full Image

Since then, the grid has evolved rapidly and renewable power has played an increasingly larger role in producing electricity. To account for these changes, Vittal and his colleagues reconvened to revisit their earlier work and redefine stability for the modern era.

The resulting paper, “Definition and Classification of Power System Stability – Revisited & Extended,” published last year, won the Institute of Electrical and Electronics Engineers’ Power & Energy Society Prize Paper Award.

Redefining stability in the age of renewable energy

Renewable power sources can operate differently than traditional fossil fuel and nuclear power generation methods, which affects the stability of the grid they supply.

Traditional methods use synchronous generators, which spin alternators with the force created by the combustion of gasses or steam to generate electricity. The alternators then produce electricity, much in the same way a car’s alternator powers its electrical system and keeps its battery charged. Since 2004, synchronous generators have a reduced level of prominence as renewable energy technologies have taken a greater role in power generation.

Solar and wind power, which have become more commonplace in power grids around the world, can’t simply be turned on or made to generate more power at will by giving them additional fuel. They also have different characteristics and tolerances for deviation from normal operating conditions.

Vittal says that synchronous generators have a high tolerance for faults in the system, such as short circuits. When synchronous generators do encounter changes in system operation, their inertia allows them to overcome these changes by utilizing the stored kinetic energy in their large rotating mass.

“The kinetic energy allows the system load or generation to vary a little,” Vittal says. “This inertia allows the kinetic energy cycle to slow down or speed up a little bit, depending upon whether there is a drop in load or an increase in load.”

In contrast, many renewable systems, such as solar generation, have no inertia in their systems to keep things spinning. This leaves them susceptible to issues like low voltage in the generation system, which can shut down an entire power grid.

Setting modern power grid stability standards

Vittal and his collaborators set out to address this conundrum: With such sensitive equipment, how do you set criteria for stability that power grid operators can use to guide renewable power generation techniques?

Over the course of eight months, Vittal and his colleagues around the world shared their knowledge and discussed the best ways to define power grid stability. This work resulted in their award-winning paper and continues to demonstrate Vittal’s leadership in the field.

Vittal says this accolade has been one of the most rewarding in his 40-year career.

“It’s very gratifying that something I played a part in was recognized by our peers,” says Vittal, who was presented the award alongside his co-authors on July 19, in Denver. “That’s always a good feeling.”

Stephen Phillips, director of the School of Electrical, Computer and Energy Engineering, one of the seven Fulton Schools, praises Vittal’s research as vital for those in electrical engineering.

“Professor Vittal’s recognition by his peers at other institutions shows the importance of his work among the entire research community in this field,” Phillips says.

The power of ASU’s electrical engineering program 

Vittal credits his students in the School of Electrical, Computer and Energy Engineering and their research in wind and solar power and grid stability to helping make the discoveries needed for the paper.

Since its original publication, this paper has become widely used as a reference for other research. Raja Ayyanar, a professor of electrical engineering in the Fulton Schools, says that it is the most downloaded and read paper in the IEEE’s Transactions on Power Systems section.

“Awards like these also help shine the spotlight on our electric power and energy systems program, giving high visibility to our extensive research on renewable energy and smart grid,” Ayyanar says.

Kory Hedman, a professor of electrical engineering in the Fulton Schools and director of the Power Systems Engineering Research Center, says Vittal’s award shows the strength of ASU’s electrical engineering program for students.

“Incoming students say that their previous professors told them if Vijay Vittal is a faculty member there, then ASU must be a top program,” Hedman says.

Anamitra Pal, an assistant professor of electrical engineering in the Fulton Schools, says the concepts outlined in the paper are important not only for Arizona and the United States, but for the world as a whole — to design power grids of the future.

Pal says Vittal is an inspiration for younger faculty through such groundbreaking research: “He truly epitomizes the adage: Lead by example.”