Optimized Cascade Fractional‐order 3dof‐controller for Frequency Regulation of a Hybrid Power System Using Marine Predators Algorithm

This article investigates the competence of a cascade fractional‐order three‐degree‐of‐freedom (CC‐FO‐3DOF) controller for power‐frequency regulation of a hybrid wind‐diesel (hyWD) power system subjected to continuous load variation and unknown/uncertain wind power perturbation. The proposed cascade controller utilizes fractional‐order 3DOF‐PID and tilt‐integral‐derivative controllers as slave and master controllers, respectively, to ensure fast disturbance rejection and high damping of power‐frequency oscillations. A disturbance observer is designed to estimate system states and unknown/uncertain wind velocity. Subsequently, an improved control law is designed by augmenting the disturbance estimation, which ensures a higher degree of robustness of the closed‐loop system against disturbances. Marine Predators algorithm (MPA) is applied to search near‐optimum settings of the proposed controller, exercising an integral error‐based objective function. The effectiveness of the proposed controller is demonstrated by comparing results with the outputs of other prevalent controllers reported in the state‐of‐art. Extensive analysis of the presented results establishes the superiority of the MPA‐tuned CC‐FO‐3DOF controller in terms of maximum peak overshoot, frequency nadir, speed of response, and steady‐state accuracy. Finally, the robust closed‐loop stability of the investigated hyWD system has been affirmed applying Kharitonov's stability method, considering dynamic variation in system parameters.