By Marlene Cimons, National Science Foundation
Consumers know all too well the inconvenience, expense and discomfort of a power failure in the aftermath of a severe thunderstorm, or the disturbances that result from brownouts during an extended heat wave. In our energy-hungry society, it can be unnerving even when the lights start to flicker.
Help is on the way. So-called smart transformers now under development potentially could transform the power grid in ways that will make power more reliable, cost-efficient and environmentally friendly, allowing consumers to both store and generate energy in addition to what they do now, which is just to use it.
“There will be a benefit to society, to the consumer and to the utility companies,” says Alex Huang, director of the FREEDM (Future Renewable Electric Energy Delivery and Management) Systems Center at North Carolina State University, which is developing these new smart solid state transformers. “They will be crucial to improving power quality and reliability for residential users and industry customers, and bringing more renewable energy onto the electricity grid.”
The nation’s power grid currently operates one way—power flows from the utility to the consumer--and traditional transformers simply change voltage from one level to another. But smart transformers, based on power semiconductor switches, are more versatile. Not only can they change voltage levels, but also can effectively control the power flow in both directions. Furthermore, they are less vulnerable to such issues as flickers and momentary voltage collapse.
With communication capability and powerful software embedded, they can communicate with each other and with the rest of the grid, making them intelligent gateways for connecting not only just electric loads, but also renewable energy generators and energy storage devices. They can monitor and control power and energy consumption, and also can change residential supply voltage and frequency as needed in response to load demand.
Most importantly, these transformers will likely change the very nature of how the country uses power. “Today, we just consume electricity,” Huang says. “With these, consumers can buy generating devices and storage devices, and your electric vehicle will be one of those storage devices. The smart transformers enable easier integration of generating and storage devices, you just plug and play. Today, if you want to do this, it is not feasible. It requires a lot of permissions and paper work to integrate these devices. Furthermore, the grid will not be stable if we have a lot of these devices without smart control.”
This means that consumers ultimately will be able to hook up a solar panel or electric car to the grid, charging electric vehicles more conveniently and economically, making them a good investment, and thus promoting the use of cleaner energy sources.
Giving utility companies the ability to incorporate large amounts of solar and wind power into the grid will “help the utility achieve the renewable energy portfolio currently required by legislation in many states,” Huang says. “Doing clean generation and storage at consumer level will also take pressure off the grid, because most power will be locally generated and locally consumed, allowing the grid to delivery power to other consumers who have not yet been able to generate and store energy on their sites.”
Huang believes the devices could be ready within five years, although it will likely take longer for the overall grid system to adapt them.
“We all plug in something to the grid every day and we take electricity for granted,” says Louis Martin-Vega, dean of NC State’s college of engineering. “These new transformers have blockbuster potential. And if gas prices keep going up, we’ll see them sooner rather than later.”
MIT’s Technology Review, in fact, recently listed the FREEDM Systems Center’s smart transformers among the world’s ten most important emerging technologies. In a statement, Stephen Cass, special projects editor for the Technology Review, says that the “rapid and precise control over electrical power could balance supply and demand better, eliminate spikes, and reduce the number of power plants required, as well as make it easier to support things like residential solar installations, or large fleets of hybrid and electric vehicles.”
The center, headquartered at NC State, was established in 2008, by a five-year $18.5 million Engineering Research Center grant from the National Science Foundation. In addition to NC State, the center also includes additional faculty and facilities from other universities, including Arizona State, Florida State, Florida A&M, Missouri University of Science and Technology, and RWTH University in Aachen, Germany.
Huang, who also is the Progress Energy Distinguished Professor of Electrical and Computer Engineering at NC State, initially used silicon based components for his early transformers, but found them unreliable and bulky at high voltages for large-scale use. So he switched to developing transformers with semiconductors made of combinations of silicon and carbon, or gallium and nitrogen, which perform better and also are smaller.
“Every home should have a smart transformer,” Huang says. “This will replace the conventional transformer located on your neighborhood utility pole. This device also is broadband-based, making your home automatically broadband enabled. You could even get rid of your current router.” More importantly, “when we have a lot of these smart transformers, our grid will perform like an energy internet, people can participate in the exchange of electrons, that is, energy,” he adds.
“Today’s power grid, which is a huge achievement, only allows power to flow in one direction,” Martin-Vega says. “Here, you’re talking about having this flow go in the other direction as well. People who are consumers of energy can also be generators of energy. It’s a lot like once upon a time, you had mainframe computers. Then PCs came along, and now there is information going in both directions.”
Ultimately, intelligent transformers will result in better power quality, fewer outages, lower costs, less reliance on fossil fuels, and greater integration of new emerging electronic devices that store energy, they say. “As soon as you have connectivity with renewable energy, you will motivate more use of renewable energy,” Martin-Vega says.
Huang agrees, adding: “This will promote green technology in a way we may not be able to predict, it will allow consumers to go out and buy things that generate and store energy, go home and plug them in and start to participate in the exchange of power. This helps both consumers and the utility companies. With these smart transformers, your home will be able to do things other than just consume energy. This will really unlock the power of people, a key ingredient for innovation.”
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