Approximately 20% of the vehicles sold last year were electric vehicles (EVs). While they present advantages — such as no tailpipe emissions, reducing sound pollution, and less dependence on foreign fossil fuels — they may also carry certain disadvantages. Electric vehicles could put pressure on the power grid.
In the Electrical and Computer Engineering Department at Texas A&M University, Dr. Thomas Overbye, a professor and director of the Texas A&M Engineering Experiment Station’s Smart Grid Center, along with Dr. Jonathan Snodgrass, a senior research engineer, are aiming to comprehend the implications of the rising quantity of EVs on the power grid — as well as how to potentially turn EVs into an asset for the grid.
“If all individuals owned an electric vehicle, it would approximately double the grid’s consumption, which is significant,” Snodgrass remarked. “The real challenge is, how do we harness the adaptability of residential charging? Because if EVs are adaptable, they can actually serve as a benefit to the grid, not merely a burden.”
Adaptive charging is utilized to preserve equilibrium, Snodgrass added. For example, currently, when an individual plugs in their vehicle overnight, charging begins right away, which adds pressure on the grid, as the grid typically experiences peak load between 4–7 p.m. However, if the intelligent features of an EV charger are leveraged to let the utility manage when charging occurs, the EV can genuinely act as a flexible load.
Known as a price-responsive load, the EV could charge during the initial three hours, halt, and then resume based on the grid’s capacity. All of this would take the driver’s requirements into account and ensure their vehicle is charged prior to their morning departure.
“Consider if you arrive home at eight or nine in the evening after running errands and collecting your children,” he explained. “When you connect your vehicle, you likely do not mind when it charges; you just want to ensure it has enough power to get you to work and school in the morning.”
Charging Levels
Typically, charging EV batteries can vary from hours to days, depending on the rate of charging. Level 1 operates on standard 120-volt home outlets and can take days to completely charge a vehicle. Level 2 utilizes a 240-volt system, similar to what water heaters require, capable of charging most electric vehicles overnight.
If a user desires to charge their EV rapidly, Level 3 fast chargers are employed, which are high-velocity charging stations. A fast charger operating at 50 to 350 kilowatts places the same electricity demand as 25 to 50 households and can replenish a vehicle in 30 to 60 minutes. As these stations possess their own converters, the vehicle does not need to depend on its slower internal converter. Nonetheless, it significantly burdens the grid.
Envision a scenario where multiple individuals simultaneously arrive at a charging station and connect their EVs to DC fast chargers. A megawatt of demand would be imposed on the power grid almost instantly, leading to fluctuations in the grid’s frequency since the equilibrium between electricity supply and demand is disrupted. The grid favors a load that varies in a predictable and gradual manner.
“The power grid can accommodate several megawatt loads, switching in and out, but it creates stress on the grid,” Snodgrass stated. “It’s not tailored for that. Imagine dropping a glass on the floor—sure, it can be done. But it’s not intended for that. It was designed to be placed down gently and picked up carefully.”
Collaborations
The research group is collaborating with the Texas A&M Transportation Institute (TTI) and ElectroTempo, a prominent software company and a startup emerging from TTI.
“TTI ranks among the finest transportation hubs globally, complemented by one of the leading grid modeling teams in the nation led by Professor Overbye, the head of energy and power in the electrical and computer engineering department. For a university, our grid modeling and simulation capabilities are among the best worldwide,” Snodgrass commented.
ElectroTempo leverages actual transportation data (i.e., genuine miles traveled) and translates it to EV miles to forecast load demands. They relay the data to Overbye’s team, who conduct grid simulations to predict the effects of a hypothetical percentage of people transitioning to EVs.
Armed with this information, they can alert utility companies regarding potential upgrades needed for distribution, transmission lines, or transformers, or if certain areas might face overload issues. Some of these challenges could be mitigated by adjusting the EV load or upgrading power lines or transformers before they reach a critical overload.
“In some scenarios, it may not be feasible to electrify a certain region. For instance, utilities should inform residents that if they genuinely want electric vehicles, the first 10% of customers can electrify without issue. Beyond that, they may need to pay an extra fee since utilities will need to upgrade your line. It varies based on how utility companies choose to manage it,” Snodgrass explained.
Funding for this investigation is overseen by the Texas A&M Engineering Experiment Station (TEES), the official research entity for Texas A&M Engineering.
The article What Can Electrifying Your Ride Do To The Grid? was first published on Texas A&M Today.