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Effects of electrical infrastructures in grid with high penetration Chapter | 8 217

balanced contribution from the bulk system, being a very effective mode of
providing phase balance for the microgrid.
These features are well characterized in Fig. 8.11. This action signifi-
cantly increases the microgrid service capacity and provides a substantial
deferral of investments in new infrastructures.
Nevertheless, once at the planning stage, the number of EVs in operation
is based on expectations which can be associated with significant uncertain-
ties. To guarantee the broadest and as precise as possible operational proce-
dure to the system operators identifying whether new infrastructures or
equipment renewal will be necessary, several simulating scenarios consider-
ing different levels of EV penetration were performed so that the microgrid
demand will be safely supplied in the future. This procedure is fundamental
to provide alternative schemes allowing the accomplishment of the system
requirements even if the predicted EV penetration is well below
expectations.
These scenarios are depicted in Table 8.4, and the results are described in
Fig. 8.12.
Fig. 8.12 also highlights the importance of controlled charging. During
islanded operation, flexible loads were operated as flexible resources and
assisted in the grid supply. So, after reconnection to the main grid, EVs and
storage units require additional supply to recharge the stored energy provided
to the grid. Still, due to the controlled charging, it is possible to notice by
comparing Figs. 8.5 and 8.8 that no sharp variation in demand was added
due to these units after reconnection to the main grid or after peak shaving,
being the additional demand request proportional to the levels of EV

TABLE 8.4 Scenarios of electric vehicle penetration and batteries.
Case Number of EVs Stationary
batteries
One-phase Three-phase Residential Total
banks
node node complex
110% 17 50 66 1297 10
100% 15 45 60 1176 10
90% 13 40 54 1035 10
70% 10 30 42 781 10
50% 7 23 30 596 10
50% 1 7 23 30 596 25
Extra
storage