*6.4. Load Shedding Assessment*

One of the last resources to mitigate electric power generation deficiency is load shedding. It consists of disconnecting the less essential loads connected to the grid. An inequality between power generation and consumption affects the power system frequency leading to a collapse [39]. Load shedding is a common practice that can be either beneficial or detrimental to the power system stability. The disconnection of considerable sizing loads creates a mismatch between mechanical and electrical power, causing a positive power acceleration that can lead to power system instability.

To assess the performance of the STATCOM after a load shedding, a 200 MW load is disconnected from Bus 9. The load shedding decreases the power flow between the two areas bringing a new condition to the generation (rotor angles). Figures 15 and 16 show the comparison between the transient response of the model-based and data-driven controllers. Regarding the real and reactive power flows shown in Figure 15, both controllers present quite a similar performance. The transient response of the AC voltage shown in Figure 16 reaches a peak voltage of 1.03 p.u. when the data-driven controller is employed. That voltage is a bit higher than that produced by the model-based controller but both controllers match very well due to both producing the same magnitude on the first oscillation and almost the same settling time. The reactive power injected by the STATCOM can be shown in Figure 16, where both controllers present a similar behavior. Notice that the load shedding will demand less reactive power as expected.

**Figure 15.** Power flows during load shedding: (**a**) active power, and (**b**) reactive power.

**Figure 16.** STATCOM: (**a**) AC voltage, and (**b**) reactive power during load shedding.
