## 4 Results and Analysis
### Fast Charging Station  
The latest set of simulations was performed with the aim of assessing how much the installation of ultra-fast charging infrastructures, characterised by a rated power of up to 150 kW, could affect the elements of a commercial network. Figure 17 presents the commercial network on which the simulation has been performed, putting in evidence where the charging stations were installed.  
In fact, the installation of this kind of charging station is still mainly located in points of interest such as shopping centres, interchange parking lots and highways. The goal is to allow recharges of up to 80% of the total battery capacity in about half an hour. However, in urban centres, the implementation of this technology is not yet widespread, but several studies [57] assume that service stations within urban centres can be converted into hybrid stations, allowing both the recharging of electric vehicles and the refuelling of those with internal combustion engines. The presence in several points of interest of a high-power multi-standard fast charging station capable of delivering DC power of up to 150 kW DC and additional 65 kW of AC power for vehicles without DC charging option and built in inverters has been assumed. According to the technical documentation of the chosen column [58], the power needed to charge the vehicles is distributed, through the dynamic power management, guaranteeing the first connected vehicle a continuous power of 120 kW, reduced to 60 kW and maintained in case of the connection of additional vehicles.  
\begin{table}
\begin{tabular}{c c c c c} \hline
**EV Penetration** & **Max. Loading (\%)** & **Time Point Max.** & **Min. Loading (\%)** & **Time Point Min.** \\ \hline
20\% & 86.531 & 19:00:00 & 24.484 & 08:00:00 \\
40\% & 102.213 & 19:00:00 & 20.961 & 10:00:00 \\
60\% & 111.563 & 19:00:00 & 22.188 & 11:00:00 \\
80\% & 128.344 & 19:00:00 & 33.997 & 09:00:00 \\ \hline \end{tabular}
\end{table}
Table 2: Rural transformer loading data.  
Figure 17: Commercial 20 kV distribution network.  
In the simulation model, an element already present in the DIgSILENT software library was used, which represents a load of MV, since the connection technical standards [59] provide that loads between 100 and 150 kW can be installed either in MV or LV, however, the choice commonly adopted by Enel, foresees the installation in MV.  
In a real condition, fast charge stations, if installed on an LV grid, can be powered directly by the transformer of secondary substation, through a dedicated feeder. The simulation predicts the worst-case scenario, in which four vehicles are connected to the charging station at the same time, assuming that the users of the service recharge their vehicle for limited time intervals, compatibly with the staying time. Exploiting an option of the simulation software, a single charging profile was used for simplicity, shifted on different time slots, assuming that in two intervals, between 12:00 a.m. and 1:00 p.m., and between 6:00 and 7:00 p.m., the peak of users could be reached, to simulate random connections of several electric vehicles that connect and disconnect to the station. The results, as depicted in Figure 18, indicate an almost full exploitation for most of the time of the charging station, in particular between 9:00 a.m. and 7:00 p.m. with the assumption that once the vehicle is fully charged in immediately disconnected, to allow the charging of another one. However, the voltage profile is still largely within the limits set by the technical standards, since the voltage drop is less than 5% even at the moment of maximum use of the charging station.