Impact of G2V on Grid

First-generation mass-market PHEVs, such as the Chevrolet Volt and Nissan Leaf [10, 11], connect to the grid for only battery charging, which is the most basic configuration. G2V includes conventional and fast battery charging systems, and the latter can stress a grid distribution network because its power is high, as a typical PHEV requires more than double an average household’s load [25]. Charging practices in different locations also have an effect on the amount of power taken from an electric grid by a fleet of PHEVs; for example, charging at work in congested urban centres can lead to undesirable peak load [12], which could require significant investments in expensive peak generation. Injected har­monics and a low power factor can be serious problems if the charger does not employ a state-of-the-art conversion for charging PHEVs at night, which has minimal impact on the power grid given suitable choices for intelligent controls [5, 13-17]. The increasing exploitation of PHEVs is still a topical area of research. One of the foremost recent studies of smart-grid development with PHEVs is [18] that recognized the complexity of studying the impact of PHEVs on a smart grid, with the results depending on many factors (power level, timing, duration of PHEV connection to the grid) and possibly affecting several variables (capacity needs, emissions generated). As mentioned above, as a charging PHEV may present a load to an electrical grid twice the order of magnitude of that of a typical home, connecting it may create power quality problems, such as momentary voltage drops. An interesting point about the simulations in [19], which assumed no control over the charging of vehicles, is that they showed voltage drops between 5 and 10.3 % depending on the time of day and season. The simulation results showed how the voltage supplied to a house changed without and with PHEV charging where, for the latter, the drop in it increased from 1.7 to 4.3 % while, for the former, much more random behaviour was exhibited with average voltage drops of around 4 % (although this eventually reached a value close to 1.7 % once the PHEV was charged). These results point to a need to improve the quality of electrical energy delivery by utilizing smart technology to coordinate the charging of PHEVs. The study in [19] was based on simulations using residential power consumption profiles. The shorter period of AC power consumption became a switched load, with levels similar to what would be expected to be observed in PHEVs with Level 2 charging profiles, that is, the notion that the grid had not experienced high-magnitude loads with a random switching profile was not true. This switching high-power AC consumption profile was masked by its aggregated effect on the grid. One other important aspect when studying the effect of PHEVs on an electric grid is the grid’s stability for which damping components will need to be introduced into future designs for controlling PHEV charging.