This study presents an innovative cascade control architecture to regulate frequency deviations caused by load disturbances in single-area and multi-area thermal power systems (TPSs) incorporating renewable energy sources. Two dual-loop control structures are developed: (i) proportional fractional-order integral–derivative–proportional–integral–filtered derivative (PIλD−PIDF) and (ii) proportional–derivative–PIDF (PD−PIDF). In these configurations, the PIλD and PD controllers are employed in the primary loops, while the PIDF controller serves as the secondary controller in the inner loops. Proper tuning of the controller parameters is crucial for effectively mitigating frequency deviations. Therefore, a recently developed artificial-ecosystem-based optimizer (AEO) is employed to determine the optimal parameter values for the proposed controllers. Initially, the performance of the proposed controllers is evaluated on a single-area TPS, with and without renewable sources, under load fluctuations. The results of the cascade configurations are also compared with the other controllers to confirm the superiority of the proposed PIλD−PIDF and PD−PIDF schemes in terms of error criteria, peak overshoots/undershoots, and settling time. Furthermore, the applicability of the proposed methodology is examined on a three-area reheated TPS to emphasize its effectiveness and contribution. The simulated results confirm that the optimized AEO-based method offers improved system performance under varying load demands and system nonlinearities. Finally, the resilience of the proposed controllers is validated under ±50% variations in the system's key parameters.
Veerendar et al. (Sun,) studied this question.