# Impact of the Integration of the Electric Vehicle on Low-Voltage Rural Networks
## 4 Impact of Uncontrolled Charging of Electric Vehicles on the Low Voltage Network  
This section examines the simulation results conducted before (Scenario 0) and after (Scenario 1) for the connection of electric vehicles in the analyzed network according to the previously described criteria. In Scenario 0, the distribution network analysis is carried out for the configuration shown in Figure 1 under current grid conditions and with the load profile illustrated in Figure 2a. In Scenario 1, 56 electric vehicles are introduced with slow charging at 3.7 kW using single-phase chargers, randomly distributed throughout the distribution network, and considering the five charging profiles outlined in Figure 2b.  
Figure 3 and Table 2 show the typical weekday results. Figure 3a compares the minimum voltage values reached in the analyzed network. As can be seen in Scenario 0, the voltage remains above 0.9 p.u. with a minimum value of 0.98. However, the increase in current due to uncontrolled charging of the EVs causes the voltage to drop, reaching a minimum of 0.84 p.u., below the prescribed lower limit of 0.9 p.u. [61]. Regarding the maximum loading, Figure 3b shows that the network is significantly oversized, with a minimum value in Scenario 0 lesser than 9.5% and a significant increase when introducing EV charging, reaching a maximum of 85.06%, which translates to an increase of 75.56%. As expected, the limiting factor in this network is the voltage at the farthest points from the transformation center, so this will be the parameter to consider when controlling the charging process, as explained in the following sections.  
During the charging process of EVs, there is a significant increase in the unbalance factor, as shown in Figure 3c. The first peak is observed at 20:00 when all vehicles are connected and charging at the same time, but after that moment, there is a reduction from 39.97% to 27.73% at 21:30, and a new increase reaching 37.00% when EVs with Profile 4 stop charging. Therefore, for the unbalance factor, it is necessary to consider not only the number of installed chargers per phase, but also the number of active chargers, which is a random number that depends on the users' habits. Global control of the charging process of the VEs can help avoid this effect as will be showed in the next sections. Figure 3d compares the losses in the low voltage lines that increase in Scenario 1 due to the current increase during the VEs charging process, as expected.  
Table 2 summarizes the most relevant results. Using Scenario 0 as a reference, the uncontrolled charging of electric vehicles, corresponding to Scenario 1, causes an increase in the current flowing through the low-voltage lines. The low load rate obtained in Scenario 0 indicates that the line is oversized, allowing for the 75.56% increase obtained in Scenario 1 without overloading. However, this result clearly shows that this situation would lead to network overload with a tighter design. Secondly, the significant increase in current produces two detrimental effects. The first one is a reduction below normal operating limits in voltage at the furthest points from the transformer. The second is a substantial increase in losses in the distribution network itself.