Abstract

In recent years, the number of electric vehicles has been at least doubling year after year. As a result, today electric vehicles already account for approximately 10% of the global automotive market, which positively affects environment in urbanized areas. However, to take full advantage of the EV integration it is necessary to use renewable sources for their charging; optimally place charging stations/terminals; optimally manage charging processes, taking into account the cost and load on the power grid; use modern power electronics technologies with increased efficiency. Nonetheless, there are several problems associated with the mass introduction of charging stations. First of all, they require the installation of additional infrastructure–substations connected to urban medium-voltage lines, transformers and converters, which is costly and it is not always possible to install them in densely populated urban areas. To remedy this, public slow charging stations that use on-board EV chargers and utilize existing low voltage grids are used. Using the same low voltage grids with fast charging stations, however, is problematic, due to increased load on the network, which can reduce power quality, the life of installed grid transformers etc. To overcome this problem, many different measures are being taken. Most of them are based on optimization of EV chargers connection points and implementation of “smart” energy management systems in order to optimize charging profiles. Additionally, as a result of the continuously growing number of grid connected EVs, their batteries can also be considered as part of a smart grid. In this case, the battery of an electric car can store energy when there is excess generation (for example from renewable sources), and supply it to the grid when there is a lack of generation, realizing the functions of vehicle to grid (V2G). Further, services like vehicle to home (V2H), vehicle to load (V2L) and vehicle to industry (V2I) can be utilized, which might positively impact grid power quality. Moreover, such solutions may be especially relevant for areas that are not connected to a centralized power network or have serious problems with network stability.

Citations

Authors (4)