Electric cars and the grid
Car owners in the United States last year bought more than 96,000 plug-in electric cars, a year-on-year increase of 84 percent from 2012. However, this growing fleet will put a lot of new strain on the nation’s aging electrical distribution systems, like transformers and underground cables, especially at times of peak demand — in the evening when people come home from work.
How to manage all these cars seeking a socket at the same time — without crashing the grid or pushing rates to the roof — has some utilities wondering, if not downright worried.
Now a team of University of Vermont scientists has created a novel solution.
"The key to our approach is to break up the request for power from each car into multiple small chunks — into packets," says Jeff Frolik, a professor in the College of Engineering and Mathematical Sciences and co-author on the new study.
By using the nation's growing network of "smart meters" — a new generation of household electric meters that communicate information back-and-forth between a house and the utility — the new approach would let a car charge for 5 or 10 minutes at a time. And then the car would "get back into the line," Frolik says, and make another request for power. If demand was low, it would continue charging, but if it was high, the car would have to wait.
"The vehicle doesn't care. And, most of the time, as long as people get charged by morning, they won't care either," says UVM's Paul Hines, an expert on power systems and co-author on the study. "By charging cars in this way, it's really easy to let everybody share the capacity that is available on the grid."
Taking a page out of how radio and internet communications are distributed, the team's strategy will allow electric utilities to spread out the demand from plug-in cars over the whole day and night. The information from the smart meter prevents the grid from being overloaded. "And the problem of peaks and valleys is becoming more pronounced as we get more intermittent power — wind and solar — in the system," says Hines. "There is a growing need to smooth out supply and demand."
At the same time, the UVM teams' invention — patent pending — would protect a car owner's privacy. A charge management device could be located at the level of, for example, a neighborhood substation. It would assess local strain on the grid. If demand weren't too high, it would randomly distribute "charge-packets" of power to those households that were putting in requests.
Read more at ENN affiliate Click Green.