Abstract
Ensuring stable voltage and frequency regulation in hybrid microgrids has become a pressing challenge due to the increasing penetration of renewable energy sources and the integration of electric vehicles. The strong coupling between active and reactive power dynamics often leads to instability, degraded dynamic performance, and difficulties in maintaining tie-line power balance. To address these challenges, this study proposes a novel cascaded controller that combines Proportional-Derivative-Acceleration (PDA) and Fractional-Order Proportional-Integral-Double Integral-Derivative (FOPIID) control strategies, optimized using Tianji's Horse Racing Optimization (THRO) algorithm. The proposed PDA-FOPIID controller functions as a robust secondary control strategy that effectively decouples voltage and frequency regulation while improving transient response. Optimization through THRO ensures superior performance compared to other well-known metaheuristic algorithms, achieving the lowest Integral Time-Square Error (ITSE) value of 0.0297. Extensive MATLAB/Simulink simulations under diverse operating conditions including step load changes, random fluctuations, multi-step perturbations, and high renewable penetration demonstrate the controller's effectiveness. Comparative results against several benchmark controllers, namely Proportional-Integral-Derivative (PID), Tilt-Integral-Derivative (TID), Fractional-Order PID (FOPID), PD-(1 + PI), and FOPI-PIDD², confirm that the proposed PDA-FOPIID achieves approximately 48% faster settling time, improved damping, and superior voltage and frequency stability. These findings highlight its potential as a promising solution for enhancing the reliability and resilience of modern hybrid microgrids with high renewable and electric vehicle integration.