Electric and Plug-In Hybrid Electric Vehicles in Smart Grids: A Review of Benefits and Challenges

Electric Vehicles (EVs) and Plug-In Hybrid Electric Vehicles (PHEVs) are gaining increasing attention owing to some unique features such as being environmentally friendly, depending on Renewable Energy Sources (RESs), having quiet operation, etc. These types of vehicles can be treated as system loads in a concept known as Grid-to-Vehicle (G2V) and/or distributed energy and power resources in a concept known as Vehicle-to-Grid (V2G). The main concern for operation of the EVs in G2V mode is that it potentially increases the daily peak load, unless an intelligent charging technique is adopted. Moreover, the charging infrastructure injects voltage and current harmonics to the distribution grid. On the other hand, the V2G mode provides reactive power control, load balancing, etc. and enables secondary services such as spinning reserve and frequency control. In this paper, the benefits and challenges arising from collaboration of the future EVs and smart grid are reviewed in details. A number of scenarios are evaluated by simulating a typical distribution grid. Although the EV charging during peak load is a serious concern and must be intelligently managed, it is shown the V2G mode has several advantages from the system perspective.