A Novel Cascaded RPIDD2-PI Controller Tuned by Enhanced Cooperation Search Algorithm for Automatic Voltage Regulator Systems

Voltage regulation is essential for maintaining the stability and efficiency of power systems, and automatic voltage regulators (AVRs) play a key role in ensuring consistent voltage levels and reducing disturbances. In this study, a novel cascaded controller, referred to as RPIDD²-PI, is proposed for AVR systems, representing its first known application in literature. The controller is designed to enhance voltage regulation by improving precision, stability, and dynamic responsiveness. To optimize the controller parameters, an improved metaheuristic algorithm called the enhanced cooperation search algorithm (ECSA) has been developed. This algorithm incorporates several features, including control randomization, a linear transfer function, an adaptive p-best mutation strategy, and a greedy selection mechanism. These enhancements provide a balanced trade-off between exploration and exploitation during the optimization process. Simulation results show that the ECSA-tuned controller achieves excellent dynamic performance, with a rise time of 0.0314 s, a settling time of 0.0472 s, and zero overshoot, outperforming existing methods. The standard deviation of 7.9591E−05 across multiple runs highlights the consistency and robustness of the solution. Robustness tests confirm the controller's reliability under parameter uncertainties in the amplifier, exciter, and generator components, showing only minor variations in dynamic performance. Furthermore, the proposed controller demonstrates strong transient stability by minimizing oscillations and enabling a fast return to steady-state conditions. Comparative studies against more than 40 recent optimization-based controllers published between 2020 and 2023 confirm that the ECSA offers faster convergence and higher efficiency.