*Performance Metrics Comparison*

To obtain high control performance, the error signal should be reduced so as to improve the tracking accuracy. Consequently, the *IAE* was minimized by tuning the corresponding gains, and therefore, the metrics in terms of error were determined during a period of two load variations. Table 4 enlists the obtained values of the IAE, *RMSE* and *RRMSE* for both controllers.

According to this table, the *IAE* revealed an expected improvement for the proposed MPC where the conventional PI showed a value of 4.48 times higher than the proposed controller. Regarding the *RMSE*, the reflection is similar for the same period. The MPC yields an *RMSE* of 0.2068, whereas the PI downgraded the performance to 0.5085, which implies a difference of 2.46 times. Finally, the *RRMSE* endures the previous trend where the proposed MPC overcame the comparisons. Hence, the PI showed a value of 12.7%, whereas the MPC diminished up to 5.17%, resembled by a 2.45-times difference.

**Table 4.** Comparison of the different metrics.

