Needed: Car experts to fend off grid disaster By David Ferris, 06/12/2023, E & E News
One way to understand the kind of problems that can arise between an electric car and the electric grid is to consider the little-known history of a different appliance: the air conditioner. That machine first arrived on the radar of Eto, the Lawrence Berkeley scientist, in 2007, when his contacts at electric utilities reported something strange. “They were concerned about what they’d seen on their power systems,” he said.
In 2010, the Dept of Energy, aided by NERC, launched an inquiry. Researchers discovered a dysfunctional relationship between the residential air conditioner and the electricity system, something that neither grid managers nor air conditioning designers had seen coming, and that significantly raised the risk of power outages.
The problems start with what is called “voltage sag.” Voltage is essentially the amount of force available to transmit electricity. A voltage sag is a disturbance, or fault, that can happen when a tree rubs against a wire, for example. Voltage sags are rare. Nonetheless, grid planners are vigilant about them because the grid depends on constant balance.
Normally a sag is extremely short — 150 milliseconds is considered long — and recovery from one is routine. What utilities started seeing with air conditioners was voltage sags that didn’t snap back.
Left uncorrected, a voltage drop can ripple from its local distribution system (one that serves a neighborhood) and through the transmission lines into other distribution systems. A result can be “cascading voltage collapse” and “widespread blackouts,” Quint and others noted in the April report.
The problem, it turns out, were air conditioners — specifically, a whole lot of them all doing the exact same thing.
Hot days were the trigger. If a voltage sag affected an area where hundreds or thousands of air conditioners were cranking, the machines’ motors would all collectively spin to a stop. In an attempt to correct this malfunction, the phalanx of air conditioners all did what they were programmed to do: draw a torrent of electrical current, five or six times of what’s normal.
“For 10 to 15 seconds they are sitting there sizzling, using tremendous amounts of power,” Quint said.That’s where the problem reaches the control room of the utility.
The air conditioner’s monster current, Eto said, “depresses voltage and keeps it down.” As grid managers puzzle over what could be causing this potential disaster, another weird thing happens. Ten to 15 seconds after the event starts, the air conditioners all abruptly go offline. The electric current has made their motors so hot that they have shut down to avoid self-destruction.
But what saved the air conditioning spawned a new wave of grid chaos.
Air conditioning is by far the largest electrical load in a home. At full tilt, Eto said, it can account for 60-80& of electricity usage. When the air conditioners on a distribution system give up all at once, the utility sees its biggest load suddenly disappear. That’s a fresh emergency. Voltage zooms back up again and can crest above its original baseline, creating a second voltage disturbance while the grid is weak from the first one.
“This can lead to cascading system failure,” Quint, Eto and others wrote in an earlier 2021 report.In sum, Quint said, the problem with air conditioners is this: “The system is not designed for a lot of devices to go offline at the same time.”
This air conditioner phenomenon now has a name: a fault-induced delayed voltage recovery, or FIDVR. While FIDVR hasn’t yet caused a blackout, the prospect causes utilities plenty of worry. Low voltages can cause transmission lines to suddenly go dead, or can knock out a power plant.
The grid has had some close calls.
One hot August day in 1998, an event in Florida caused 825 megawatts to suddenly disappear. In 1999, south of Atlanta, 1,900 MW — the output of a sizable nuclear power plant — was dropped. Both of those were dwarfed by what happened in Southern California in the summer of 1997, when a plane hit a power line and caused a whopping 3,500 MW of power to vanish, leaving utility engineers scrambling to prevent a cascading blackout from the seesawing voltages.
Preventing such problems can be costly for utilities and their ratepayers. For example, Eto said that Southern California Edison, a major electricity provider in Southern California, spent $50 million to harden a substation against FIDVR problems. The utility did not respond to a request for more information.
According to Quint, all this was preventable; the air conditioners didn’t all have to act in concert and present these problems to the electric grid. The problem is that they were designed without the fine-grained operations of the grid in mind. That, he said, is a lesson that the automakers need to internalize as they prepare to push millions of EVs into America’s garages.
“In aggregate,” Quint said, “devices that act identically to each other can have an impact if they’re doing the same thing.”A pair of power pigs
----------------- With EVs, Quint and his colleagues say the air conditioner phenomenon might be repeating itself, but with greater intensity.
The worry is not just that EVs could borrow from the air conditioning playbook and misbehave in lockstep. Their biggest concern is that EVs could misbehave on precisely the same schedule, compounding the already severe consequences of a FIDVR event.
A typical home EV charger hogs even more electricity than a busy air conditioner. The two of them together — in a hotter world, with an electric car in every garage — makes the interaction between them highly consequential for the grid.
Two years ago, Quint, Eto and other researchers explored the scenario in a study for the Pacific Northwest National Laboratory. They simulated a situation that in the coming decades is unlikely but possible: a distribution system of 1,500 homes at the exurban edge of Phoenix where, at one moment, every air conditioner is running and every car is charging.
“Which is fine,” Quint said, “unless thousand and thousands of cars are all doing the same thing at the same time.”The study used input data from six EVs — a blend of actual models and simulated models — to see how they behaved.
What they didn’t want was for the EVs to act like air conditioners and continue to draw power when there’s a voltage sag. Instead, they were hoping the EVs would in essence say, “I’m getting off, and will get back on when the grid is at a good healthy spot,” Quint said.
Both options would be essentially unnoticeable to the EV’s owner. The pause would comprise only a few seconds or minutes of an hourslong charging session.
The study returned a mixed answer. Two EV models magnified the glitches caused by the air conditioners’ FIDVR habits. One split the difference, causing problems in one area but not another. Three others caused no problems.
However, this information offers Quint only the haziest hint of how future EVs will behave. Hundreds of versions of new electric SUVs, sedans, trucks and hatchbacks will roll off production lines in the coming years.
It’s possible their power systems will be designed to react at the intervals of millionths of a second and prevent headaches for power managers. Or it’s possible this bug is not even on automakers’ radar. Lacking information from the automakers’ engineers, Quint can only speculate.
“You could program the thing to be grid-friendly,” he mused, “or you could program the thing to be grid-unfriendly.”No one to call
--------------- To prepare for the coming onslaught of EVs, utility experts find themselves with a distressingly small list of contacts.
“We are talking to whoever will talk to us at this point,” said Eto.The task is complicated by the fact that the auto and utility industries are not just huge, but also hugely distributed. Quint, Eto and their colleagues are but a small band of overseers for the more than 3,000 U.S. electric utilities. The automotive side has fewer actors, but still plenty: The Alliance for Automotive Innovation, the main U.S. auto trade group, has 20 automaker members.
Even those well-connected in the auto industry wouldn’t quite know where to look.
“Some of these companies are very large,” said Frank Menchaca, the head of the sustainability-innovation arm of SAE International, one of the chief technical standards-making bodies for the global auto industry. “Responsibility can be really widely dispersed in large companies. It would take the chain of communications to find the answer,” Menchaca said, referring to the difficulty of finding the specific engineers overseeing electrical systems.SAE has a group that creates the very standards of interest to Quint and his cohort. Called J2894, it addresses power-quality issues for EV chargers. Like all of SAE’s groups, it is made up of volunteers, chiefly experts who work for automakers and their suppliers.
Like all standards bodies in competitive industries, SAE has internal tensions. Its engineer members may want to share information, but are on tight leashes by their employers, who don’t want to reveal the company’s strategies and secrets.
As if to prove the point, one of the heads of SAE’s J2894 group, an engineer for Nissan Motor Corp. based in Michigan, told E&E News he would try to speak after getting permission from his company — and then stopped responding to emails.
The growing nodes
--------------- One source of hope for Quint and NERC is that others in the utility industry have made inroads to the automotive world.
For example, EPRI, a nonprofit that guides utility technology and policy, has convened automakers and utilities since the early 1990s, and those conversations have shaped the EV and charging ecosystem we know today.
“You need to make sure the standards are very clear,” said John Halliwell, an executive on EPRI’s electric transportation team, “and you’re still seeing some growing pains.”Utility and automaker collaborations are getting more sophisticated. Last month in California, the utility Pacific Gas & Electric Co. and automaker BMW of North America LLC announced they are working on a project to integrate EV charging with the grid in a way that harnesses excess renewable energy.
Some big-picture cooperation are a couple years underway, like the EV Charging Initiative, a group that includes the Alliance for Automotive Innovation, along with utility, environmental and government officials.
Other forums are just getting started.
SAE, the auto standards group, will play a prominent role in the Biden administration’s ChargeX initiative that was unveiled last month. It will take the lead, alongside national laboratories, in establishing data rules that could resolve nagging reliability problems.
Still, the massive size and complexity of both the automaking industry and the electric grid makes the prospect of their integration a long one. It is unclear if they are moving fast enough, and the topics they have to address — like the vexations of voltage — keep popping up
“There will be more convening to do,” said Kelly Fleming, a fellow at the nonprofit research group the Institute for Transportation Decarbonization, “because these problems are going to continue to happen.”