Controlling EV charge loads to minimise impact on the grid

“I believe that EV charging is one of the top transformation opportunities for our customers and our industry. Being prepared for what is coming, actually what is already among us is crucial.”

That was the opening statement of Jay Hoffman, Customer Services Support Director at American Electric Power in a session hosted by Itron Inspire entitled ‘Electric Vehicle Charging Impacts on the Power Grid’.

The session focused on how the increasing adoption of EVs is impacting the grid, as well as how best to measure and manage load requirements in the most cost-effective way.

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Mark Braby, Global Head of EV, Payments and Partners, Itron, stated that even though EVs have been around for a while, now is the time to be thinking of the impact of EVs on the grid. “We are now at a pivotal point of the EV market, in terms of adoption.”.

Braby highlighted the main factors driving EVs in the US and emphasised that utilities should be considering strategies to get ready for what’s coming.

Factors driving EVs:

• Vehicles are coming to market, light and heavy-duty, and last-mile delivery vehicles. More auto companies getting into the market. This means that battery sizes are increasing across all vehicle sizes. This implies increased load and increased constraints on the grid.
• Accelerated investment from OEMs. OEMs are upping their commitment to going electric and accelerating their vertical integration around EVs and accelerating investment from the public market.
• Infrastructure bill. The government has made a commitment to electrify 50% of its fleet by 2030. 7.5 billion to advance EV infrastructure.

According to Itron’s 2021 Resourcefulness Report, utility execs consider EV integration as one of the top three priority challenges. Grid modernisation strategies now should be done with or considered alongside grid preparation for EV integration and renewables.

“The thinking should be to consider upgrading the grid, as well as thinking about the impact that these distributed energy resources will have on the grid,” stated Braby.

Manish Mohanpurkar, Senior Researcher, National Renewable Energy Laboratory, spoke about measuring the charge load needed for EVs.

Said Mohanpurkar: “There is now greater overlap between the electricity and transport sectors, where the transport fuel itself will be delivered by the electric grid”.

To understand the scale of load that utilities are facing, Mohanpurkar explained that an average light-duty EV battery range is 33-110kWh, and a typical heavy-duty EV battery ranges between 500-760 kWh. This indicates the energy needed in terms of AC (residential) or DC (high power) charging.

On the horizon are MegaWatt charging systems, which can charge a heavy-duty truck at a few MW charge rate. “As you can imagine, this could be a bit tricky, from the power quality standpoint, voltage flickers, and a host of other things associated with these challenges. This could also lead to trips in neighbouring grids,” said Mohanpurkar.

“There are several projections out there that tell us what EVs at scale means. In general, it means tens of millions of light-duty vehicles and a few thousand medium to heavy-duty vehicles. If I selected a particular projection scenario, I would select the EPRI projection, which says in the year 2030 there will be about 14 million EVs, which on an average of 12,000 miles travelled per year, roughly translates to about 60TWh a year, just in the US, for light-duty vehicles.”

Mohanpurkar continued: “Including medium and heavy-duty vehicles, about 100TWh would be needed for this particular scenario.”

There are typically two charge patterns, according to Mohanpurkar, ‘as soon as possible charging’ which causes an early evening peak and ‘as late as possible charging’, which leads to an early morning peak.

Charging in an uncontrolled fashion would create more significant peaks, said Mohanpurkar. However, there are enabling technologies available to help manage these loads, as well as aggregators, distribution management and station management systems.

“It’s about understanding what the utility and grid need and finding out what the EV user needs and trying to find the right balance.”

Mohanpurkar highlighted that maintaining voltage quality is very important and can be achieved by delaying charging in a smart manner.

Charging EVs with microgrids is another option that increases resilience, by allowing islanding options and operating as a single controllable entity.

Of course, there are economic impacts for utilities when it comes to utilising charging management, whether approaching it from the grid or end customer perspective.

Braby elaborated on how charging management can benefit the utility if strategies around time-of-charging and locational distribution management are implemented. He compared the total costs involved between upgraded grids to accommodate charging management and the costs of an unoptimised grid.

According to studies referred to by Braby, “The difference between unoptimised and optimised is roughly $3100 per vehicle over the next ten years.”

“It’s also important to think about the second-order impact of that, as those costs will need to be passed on to end customers. Impacts on rates can be significant.”

Strategic ways to implement managed charging are clearly needed and utilities need to weigh cost and benefit to find the sweet spot for an optimised grid.

The session is available on demand or you can find out about other Itron Inspire sessions here.