The next step after the user priority evaluation is the definition of its assigned charging rate (indicated as CR). Two different strategies are considered herein to determine the charging rate of a user in a generic time slot. The first approach is called “Maximum Energy With Priority” (MEWP), and consists in allocating all the energy required by the user in order to complete his charging process by the end of the current time slot. In this case, the
charging rate is given by the ratio between the energy still required by the user and the slot duration, i.e. CR = ER(t)/t. The second approach is called “Spread Energy With Priority” (SEWP), and consists in spreading the energy to be still supplied to the user over the entire time period available before the user leaves the system. In this case, the charging rate is calculated as CR = ER(t)/TR(t). Simulations were performed to evaluate the impact of the MEWP
and SEWP approaches for the six vehicles of Table 1. As shown by results in Tables 2 and 3, the two smart approaches lead to a significant increase in both the degrees of user satisfaction and the total profit of the utility with respect to the FR-FCFS strategy because
of a better exploitation of the grid potentiality. Fig. 2 clearly evidences that the total allocated power by using MEWP and SEWP is almost equal to the maximum power available from the grid for the greater part of the process. The comparison between data in Tables 2 and 3 shows that the MEWP and SEWP methods are almost equivalent when a unitary constant charging efficiency is assumed. In the next section, the impact of the charging efficiency will be analyzed.