Usually when talk turns to artificial intelligence (AI) and electric vehicles (EV), it seems natural for the discussion to focus on self-driving cars. Autonomous vehicles are one of the hottest topics in the media today. Sure, it would be great to sit back on the morning commute and read the latest copy of T&D World magazine while enjoying a cup of coffee and ignoring the traffic congestion. For the power gird, however, there are many more important subjects to explore when AI and EVs are combined than driverless cars. Probably the most pressing problem is the growing number of EVs. A study by the Edison Electric Institute (EEI), estimates that the annual sales of plug-in electric vehicles will exceed 1.2 million vehicles by 2025 in the United States alone. EEI said the number of plug-ins on the road would reach 7 million by 2025 and would require about 5 million charge ports to support them.
It’s an infrastructure issue that is causing utility planners some sleepless nights. The Utility Analytics Institute (UAI), a sister brand to T&D World, reported, "In mid-April, Oregon regulators adopted a new rule to compel utilities in that state to increase the speed and degree of their support for EV adoption." The story went on to say, "Other utilities and regulators are pursuing similarly ambitious EV infrastructure and adoption support agendas."
In addition, UAI sees many states reporting 100% yearly growth in electric vehicle sales. Of course, California is the largest market for EVs in the U.S. accounting for 5.02% of all EVs sold in 2017. Interestingly, UAI points out that California leads the country in time-of-use (TOU) rate programs too. In addition, utilities across California are actively promoting both EVs and TOU programs. Arizona, Rhode Island and Minnesota are also planning to offer TOU rates.
So, what are the infrastructure problems? Probably one of the biggest coming to mind is balancing load with supply during the peak times with the numbers of EVs projected to be added to the grid. TOU programs do offer help, since they encourage EV owners to charge their vehicles during off-peak periods, but regulators and policymakers have to get on board first. Then there are other issues; padmounted and pole-mounted transformers are going to be stressed when the neighborhood goes EV-happy, and what about harmonic currents and power factor issues.
Also, there are concerns that conductor and cable will have to be upgraded to handle the increased power flow over distribution circuits. Another issue is the discharge of stored energy into the distribution network when the EV is being used as a distributed resource. Some of these issues are valid, some are hype from EV cynics, and some will be handled by emerging technologies. Since EVs are gaining acceptance throughout the world, there is one certainty — the grid will have to be ready for them.
Electric Vehicle Technology
Before going on, let’s look at the types EV technology in use today. It is a bit confusing with all the terms and abbreviations being tossed around. The Department of Energy’s (DOE) Office of Energy Efficiency & Renewable Energy breaks EVs into two categories all electric (AEV) and the plug-in hybrid (PHEV). The AEV includes battery electric vehicles (BEV) and the fuel cell electric vehicle (FCEV). Other groups divide these categories into some other offshoots, but DOE’s report keeps it simple and that’s good for an overview discussion of the technology. Things get a little complicated when discussion moves to charging choices and types of plugs.
Without getting into a lot of theory, there are three types of charging: slow, fast and rapid. The time required depends on several factors such as the maximum current available and how fast the vehicle can accept the charge. There is a lot of research and development (R&D) under way on charger technology by the major grid suppliers like ABB, Siemens, Schneider Electric, Tesla Motors, Leviton Manufacturing, ChargePiont Inc., and others.
Basically EV chargers are grouped by voltage levels into three categories. Level 1 chargers use 120 V, level 2 chargers use 208 V or 240 V, and level 3 are the direct current (DC) fast charging systems. In general terms, level 1 is usually found in homes requiring eight to 12 hours to fully charge. Level 2 are found at homes and public charging facilities and typically take about four hours to charge. Level 3 are found at dedicated charging stations and take about 30 minutes to charge.
When it comes to connectors (the plug), there doesn’t seem to be a standard. As a matter of fact, some groups are calling it the plug wars as EV manufacturers vie for market control. The level 1 charging stations have at least four plug configurations, and level 2 uses four plug types. Fast DC charging stations use three entirely different plug types. It seems all technologies go through this type of shake out — remember the format battle when digital recorders first came into the marketplace.
EV charger R&D has also been focused on improving the grid interaction by combining charger technology with artificial intelligence (AI). It’s being called a smart charger. These devices come with varying abilities. Some are little more than clock-controlled switches that the EV owner plugs the EV into and sets a time for charging to begin and end. The timers rely on input from a human and can’t take advantage of rate variations. As previously mentioned, various TOU programs are gaining interest from utilities and regulators. Smart meter technology has made real-time TOU possible, but it’s hard to say if that will come to pass.
So let’s look at what is happening with smart chargers. They are being networked with smartphones, which allow customers to start and stop the charging process when utilities offer incentives. Another variation of this concept was recently announced by SolarEdge Technologies and Google. They have formed a collaboration to improve the EV charging experience for the customer with solar panels. By integrating Google’s AI powered Assistant with the SolarEdge EV charging solar inverter, they have given users control of SolarEdge’s EV charging solar inverter using familiar Google Assistant commands. SolarEdge said this is the world’s first EV charging solar inverter and is six times faster charging than standard level 1 chargers.
Another aspect is the smarter charger infused with AI technology using smart grid interconnectivity for load management. There is R&D in AI-powered smart chargers to control when the charging takes place by analyzing grid data to select the most opportune times for the grid. Some of these systems include machine learning to look at the feeder and spread charge times across multiple EVs to reduce stress to the feeder’s components. The algorithms help the chargers adapt to what is happening on the grid and know when not to add to the peak demand. These AI-powered smart chargers should be a tremendous tool when dealing with EV fleets or parking lots full of EVs connected to the grid.
There are a couple of technological wrinkles of interest in the enhanced charger field. These devices are interactive with smart grid technology and called vehicle-to-grid (V2G) and grid-to-vehicle (G2V). These are bidirectional systems, giving the EV owner the ability to draw electricity off the grid when it is cheap or to sell it back during peak hours. Currently they are only available in level 1 and 2 chargers, but you have to start somewhere. EV owners can buy V2G/G2V devices individually or they can work with established aggregators for improved returns. The goal for the typical EV owner is to balance their electricity purchases with electricity sales letting them drive for free, but it helps the grid too.
In late 2018, Enel X’s eMotorWerks subsidiary issued a press release that said they have installed more than 6,000 network connected EV chargers in California. This represents a 30 MW/70 MWh virtual battery. These EV chargers are placed mostly in homes and are connected using their JuiceNet cloud software platform as the battery management system. eMotorWerks’ press release said, "The eMotorWerks virtual battery is active in California Independent System Operator (CAISO) wholesale day-ahead and real-time markets, dynamically managing charging loads to balance grid demand, reduce wholesale energy costs and mitigate the intermittency of renewables."
Batteries on Wheels
It’s estimated there were more than 4 million EVs on the roads worldwide in 2018. The battery capacity of EVs range from about 30 kWh to 100 kWh. Several reports say that 60 kWh is a good average figure. Multiply that 60 kWh by 4 million and you have a great deal of load and an extremely large amount of energy storage. They promise to improve distributed energy resources, provide storage for renewables, improve with load management, increased bidirectional power flows and many other grid enhancing benefits, but there are issues.
Utilities must prepare for an increase in EVs. EEI said it best, "Electric transportation is a win-win. It meets customer needs, provides environmental benefits, and supports America’s energy security."