5.2.1. Active Power Priority

In this case, the normal MPPT control is used during the day as it is illustrated in Figure 22. Taking into account this control, the maximum reactive power that the PV generator can absorb is illustrated in Figure 23 together with the operational area. It can be seen, that the maximum reactive power that the PV generator can absorb is variable in the time as it is not a priority. The reactive power varies from 0.6 pu to 1 p.u depending on the time of the day.

In the case that a reference of absorbed reactive power is required (*Qref* = −0.8 p.u) by the PV generator and the MPPT is still used, the response of it is illustrated in Figure 24 together with the operational area. With these conditions, the PV generator can follow the reactive power reference between some hours (06:00 to 08:00 and 15:00 to 18:00). However, when the active power exceeds a certain value, the PV generator cannot follow the reference of reactive power.

**Figure 22.** Active power response for day 3 considering MPPT.

**Figure 23.** Absorbed reactive power when MPPT is considered (**a**) Maximum possible reactive power and (**b**) Operational area.

**Figure 24.** Absorbed reactive power when a reference of reactive power is considered (**a**) Response of reactive power (**b**) Operational area.

For a *Qref* = 0.8 p.u, the PV generator can inject the reactive power depending on the voltage limitation and the modulation index. A modulation index of 1 and 1.75 is tested and illustrated in Figures 25 and 26 respectively together with their operation area. When the modulation index is 1, the reactive power is equal to 0.45 p.u for any solar irradiance. Meanwhile, when the modulation index is 1.75, the reference of reactive power is reached from 07:00 to 10:00 and from 13:30 to 18:00. However, from 10:00 to 13:00, the reference of reactive power is not reached. Instead, the maximum possible reactive power is injected, which depends on the solar irradiance. The curve that limits its behavior from 10:00 to 13:00 is the current curve, for the rest of the day it is the voltage curve.

**Figure 25.** Injected reactive power with MPPT control and *M* = 1 (**a**) Response of reactive power and (**b**) Operational area.

**Figure 26.** Injected reactive power with MPPT control and *M* = 1.75 (**a**) Response of reactive power and (**b**) Operational area.
