A Question of Standards
Written by Travis Bouslog and Doug Houseman
With the announcement in 2021 by Ford and GM that their standard electric vehicle chargers (EVSE) will demand 19.2 kilowatt (KW) from now on, many utilities are running quick calculations on what the impact is on circuits and how many electric vehicles (EV) they will be able to support. Sadly, the answer on most circuits is, not nearly enough to be able to support the automaker's announced plans to electrify the majority of new vehicles they will be building within 8 years.
With the existing loads on US-style (60Hz) 5 kilovolt (KV)) residential distribution circuits, the number of chargers most circuits can support, assuming diversity of time and frequency of use, is under 10% of the total customers per circuit. Note that there is very little data available to support the assumption that EV charging will be spread out across time and days of the week. Some European communities (50Hz) secondary networks are showing that less than 10% of customers on a circuit can be supported at this level of EV charging demand even with charging diversity. It almost doesn’t matter where you are in the world, as existing power distribution grids are not set up to handle the expected level of demand from these chargers. Nor was the grid designed and built to handle even the previously specified and supplied 8KW EV chargers in quantity.
With the announcement made and the chargers (and the vehicles that will use them) now in production, 19.2 kW charging stations will start being installed by the spring of 2022. Ford has announced plans to produce 650,000 EVs in North America alone during 2022. Tesla, not to be outdone, has suggested they will release an “even faster” 25KW charger in 2022 while continuing to build as many EVs as they can. Nothing is being done to stop the commercial rollout of these chargers, so what will the electric power industry need to do to cope?
There are at least six options of varying cost and complexity that are reasonable to contemplate.
- The industry can split distribution circuits into smaller pieces and add substations as needed.
This is an extremely time consuming and expensive option. It will likely leave some areas without adequate distribution to support EVs until 2060 or later, which raises questions of social justice and how to globally allocate equipment or train enough workers to do the required construction.
- The industry can raise voltages on existing circuits, allowing more energy to flow over existing rights of way.
This will be less effective in 50Hz systems with large secondary systems. In both 50 Hz and 60 Hz systems, raising circuit voltage will create additional impacts on sub-transmission, transmission, and substation equipment. This option requires a complex dance of coordinated changes, including changes to the spacing and the size of conductors on overhead lines, upgrading hundreds of service transformers, and upgrading existing transformers in substations. In one project that has been studied, raising voltage requires upgrading an already overloaded 10 megavolt-amp (MVA) substation to 70 MVA.
- The premise owners can be encouraged to install solar plus storage to locally produce the energy to charge their vehicles.
For people at 45 degrees north latitude in Mid-December, 100 KW of solar would be required to produce enough power to charge a work truck at home with a 200 KWH battery and at least 200 KWH of on-premise storage. This is a cost most homeowners cannot easily afford and exceeds the available land area for many premises. This option is not legally available to most renters or those who live in attached homes such as condominiums or duplexes. In some countries, this much solar generation and storage at a single-family home will violate fire protection regulations without expensive renovations to install fire walls.
- Change the way people charge EVs to require or encourage daytime charging only. Don’t allow, or substantially increase the price of power used overnight for charging at home.
In 2021, 84% of current EV owners in the US and 74% in Europe surveyed exclusively charge their vehicles at home, at night. Globally there are only a few million current EV owners who would have to be retrained to change this pattern. However, most current EV owners are not willing to give up the convenience of charging at home. This change would probably negatively impact sales rates of EVs in areas that adopt it. California has already moved to lower daytime rates as part of their time of use rates for customers, which led to a corresponding increase in complaints from current EV owners.
- Insert communications and control into EVSEs at premises, allowing the utility to manage the rate of charge as well as the charging times of all the chargers on a single circuit (or secondary network).
Right now, EVSE under 50KW are largely dumb devices. Insert the wand into the vehicle and they charge; when the vehicle is full, they stop charging. Adding communications, cyber-security, and control will be a non-trivial effort that requires the development and enforcement of industry standards for grid-to-charger or grid-to-vehicle communications. SAE has created some of the required standards; IEEE 2030.5 is a key piece of the puzzle, and so is OpenADR. Getting these standards adopted by the more than 100 EV manufacturers and 400 EVSE manufacturers will be an uphill battle.
- Change the metering infrastructure to allow EV chargers (1 to N per customer premise) to be monitored and controlled by the utility separately from other loads.
While this can be accomplished within each premise’s breaker panel, that panel tends to be owned by the premise owner, not the utility. To overcome that challenge, the controls need to be accomplished by installing a new style of AMI meter with 2 to N modules that aggregate through a common control and communications module. Even with transactive energy or prices to devices type tariffs, measurement will need to be disaggregated. Further, Ohm’s law says that if the switch is closed and there is demand, that the electricity will flow. ANSI has a range of metering standards in the US, and IEC in Europe, but none of them have yet contemplated this type of evolution in AMI.
Other, smart people can devise other ways to do this, but no one yet knows all the possible methods that might work. Other methods take time to be modeled, prototyped and standardized. If there are better choices, they need to surface soon.
This is not a trivial matter. In mid-size commuter communities, widespread adoption of EVs will more than double the total amount of electric power consumed by and at residences within each community. Even if we achieve massive improvements in home energy efficiency and demand side management, on a cold winter night, switching a community from its current mix of energy usage to all-electric appliances will seriously impact existing grid infrastructure.
None of the adaptation methods will work without interoperable systems, which means we need strong standards with few or no options that allow the creation of incompatible equipment or control systems. For most of these options to work, additional standards or revisions to existing standards are urgently required. The standards covering interoperability will require testing standards that are clear, with no wiggle room for multiple incompatible implementations by different manufacturers. Governments and regulators will have to adopt these standards and enforce them, not an easy task to achieve.
IEEE has taken the lead in developing and revising many of the necessary standards. They cover the gamut of electric power system requirements from communications to cyber security, to physical devices, to other needs. Continuing to work with SAE and other standard-setting organizations to avoid a “not invented here” issue is critical, as is getting standards drafts approved and implemented before 2024, when Ford plans to be producing 3 million electric vehicles per year. GM is also close behind. Socializing these approaches with regulators and national governments must become a top priority.
This article edited by Doug Houseman.
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