Report Says Industry Collaboration Needed to Ensure Reliability as EV Use Grows

by Peter Maloney
APPA News
April 15, 2023

A new report by the North American Electric Reliability Corp. and utility groups highlights the need for collaboration between electric utilities and the electric vehicle industry to ensure electric system reliability.

The report, Electric Vehicle Dynamic Charging Performance Characteristics during Bulk Power System Disturbances, was jointly developed by the California Mobility Center, the North American Electric Reliability Corp., and the Western Electricity Coordinating Council.

The report focuses on electric vehicle charging behavior during infrequent disturbances that originate from the high-voltage bulk power system. The events last no more than a few seconds, but if left unchecked they have the potential to cause catastrophic consequences for electric system reliability such as cascading blackouts and widespread power interruptions, the report said.

The report stresses the need for early engagement, collaboration and information exchange between electric utilities and the electric vehicle industry in anticipation of a projected increase in electric vehicle adoption and charging.

The Energy Information Administration forecasts that electricity consumption by the transportation sector will increase by more than a factor of 12 between 2021 and 2050 – from 12 billion kilowatt hours in 2021 to more than 145 billion kilowatt hours in 2050.

“By forming a working group to bring all EV stakeholders together, we can better accelerate innovation and help prevent grid reliability challenges before they happen,” Arlen Orchard, California Mobility Center chair, said in a statement. “This is precisely the type of cutting-edge cross-sector collaboration that the CMC seeks to foster.”

The rapid growth of electric vehicle charging is “unprecedented” and taking place at the same time electricity system operators and planners are addressing rapidly growing levels of inverter-based generation resources, extreme weather impacts, and increasingly malicious security threats, the report noted. The effect of these changes on the electric power system “will only intensify as the penetration of EVs on the grid increases,” the report’s authors said.

The report highlighted several potential effects from the rapid growth of electric vehicle charging stations, including:

• Demands on distribution providers to process electric vehicle charging load interconnection requests may increase faster than can be managed by providers and lead to delays in new interconnections.
• A significant increase in distribution system hosting capacity may cause operational problems in distribution systems requiring expensive, last-minute upgrades in order to accommodate EV charging demands.
• Large-scale changes to demand profiles due to unmanaged EV charging behavior, time-of-use rates, and distributed renewable energy resources may lead to resource adequacy shortfalls and create needs for short-term, emergency rationing, such as planned, rolling blackouts.
• The need for flexible ramping resources and reserves carried by balancing authorities and transmission operators may grow faster than has been anticipated in long-term planning studies.

The report put forward several recommendations that could provide a basis for further testing of for “grid friendly” electric vehicle charging practices, including:

• The electric vehicle industry should employ a steady-state control strategy that uses constant current control rather than constant power level control during normal operations.
• Electric vehicle chargers should operate with a power factor of 0.985 or higher, which should be maintained for alternating current voltages from 80 percent to 110 percent of nominal voltage.
• Electric vehicle chargers and supply equipment should have a programmable current consumption droop characteristic with a programmable range and a default value of 5 percent.

Ride-through performance and capability is also an important consideration, the report said. The authors recommended that electric vehicle chargers and supply equipment should remain connected during grid disturbances and should not require any advanced communications between devices or with the grid operators. Instead, converter protection and controls should respond automatically to modify electric vehicle charging behavior and operation.

However, the report’s authors also noted, “preliminary testing has confirmed that some EV chargers already appear to behave in a manner that is grid friendly during the very infrequent, short-lived times (lasting no more than seconds) when the grid is under stress. This is encouraging because it suggests that only modest changes might be required to make all EV charging and EVSE technologies operate in a grid-friendly manner.

In terms of next steps, the North American Electric Reliability Corp. and its industry stakeholders are developing and testing a new aggregate electric vehicle charging load model that can be used in bulk power system grid reliability studies. The report’s authors said the North American Electric Reliability Corp. would soon be releasing its findings on the usability of the aggregate electric vehicle charging load model, as well as the possible impacts to bulk power system grid reliability that will occur with rapidly growing electric vehicle charging loads across North America.