|Simple block diagram of an EV with V2G. Source: Chakraborty et al. Click to enlarge.|
Researchers at the US Department of Energy’s National Renewable Energy Laboratory (NREL) released a technical report that provides an interim test plan for evaluating vehicle-to-grid (V2G) applications. The test plan is designed to test and evaluate the plug-in vehicle’s capability to provide power to the grid, and to evaluate the vehicle’s ability to connect and disconnect from the utility according to a subset of the IEEE Std. 1547 tests.
The intent of the report is to provide a way to evaluate V2G applications for utility interconnection, helping to pave the way for wider use of EVs and plug-in hybrids, as well as clean renewable energy for transportation in the future. Once validated, these procedures could become the basis for testing standards for V2G applications.
The test plan does not include all the tests required to meet the 1547 standard due to the uniqueness of the battery-based V2G power electronics that makes some of the IEEE Std. 1547 tests unfeasible or impractical, the NREL team said. In exchange, some additional performance tests are included in the test plan to verify the V2G-capable vehicle’s continuous output power, efficiency and losses.
Almost all the tests described in the document are for V2G modes only, the authors emphasized, not for modes in which the vehicle is charging its batteries from the grid. Only one test is provided for grid-to-vehicle battery charging, and is included to estimate the time it takes to charge the battery based on varying conditions as the amount of time and power required to charge will be of interest to utilities who must provide the infrastructure to provide electricity to plug-in vehicles.
|Example of V2G test setup. Click to enlarge.|
Engineering vehicles capable of interconnecting to the power system for bi-directional power flow is a key component of emerging vehicle-to-grid systems, in which plug-in EVs communicate with the power grid to deliver electricity or modulate their charging rates. The global vehicle-to-grid (V2G) market is expected to grow at a rapid pace, reaching the $2.25 billion mark in 2012 and accelerating to $40.4 billion by 2020, according to a new market analysis from GlobalData.
This report offers the first nationally available set of test procedures for V2G applications. Unleashing the potential of electric vehicles to optimize grid performance will be instrumental as the world moves to a smart grid with much higher use of renewables, energy storage and load control.—NREL Director of Energy Systems Integration Ben Kroposki
The report includes a general discussion on safety requirements and general test setup, as well as an overview of vehicle characteristics and test equipment. Each test scenario discusses the purpose of the test, test procedure, corresponding standards, and how the results are reported.
NREL has developed these procedures based on our experience testing V2G-capable electric and hybrid vehicles. As we test additional vehicles, we expect that the test procedure will evolve to become more universal.—Sudipta Chakraborty, NREL research engineer and lead author of the report
Funding for the development of the test procedures was provided by the US Department of Energy’s Office of Electricity Delivery and Energy Reliability.
S. Chakraborty, W. Kramer, B. Kroposki, G. Martin, P. McNutt, M. Kuss, T. Markel, and A. Hoke (2011) Interim Test Procedures for Evaluating Electrical Performance and Grid Integration of Vehicle-to-Grid Applications (NREL/TP-5500-51001)