Chess-Optimized Fuzzy-2DOF-PID Controller for Load Frequency Stabilization in Interconnected Multi-Area Renewable Grids

The Load Frequency Control (LFC) challenge in multi-source power systems increasingly complicates with the integration of renewable energy, owing to frequent nonlinearities, uncertainties, and disturbances. Conventional controllers such as proportional-integral-derivative (PID) and adaptive PI–1PD frequently exhibit constraints in terms of stability and convergence speed. This study proposes an optimal fuzzy logic two-degree-of-freedom PID controller (Optimal–FL–2DOF–PID) tuned via a metaheuristic chess optimizer (CO), which is a novel optimization algorithm introduced in this study. The performance was evaluated in MATLAB/Simulink under two scenarios: (i) a 5% Step Load Perturbation (SLP) and (ii) a Random Step Load Pattern (RSLP) increment-decrement that effectively mirrors real-world applications. The simulation results demonstrate that the Optimal–FL–2DOF–PID controller surpasses all the comparable controllers. In Scenario 1, the proposed controller attains the lowest objective function—Integral of Timeweighted Absolute Error (ITAE) of 4.6692 corresponding to reductions of 25.31%, 43.05%, and 41.92% relative to 2DOF–PID, PID, and PI–1PD, respectively (and 1.92% relative to the None–optimal–FL–2DOF– PID), overshoot (OS), undershoot (US), settling time (ST) 13–15 s, and tie-line power deviations are likewise reduced. In Scenario 2, using the corresponding optimum parameters from Scenario 1, the Optimal–FL– 2DOF–PID controller achieves ITAE = 395.72, which is lower than the None–optimal–FL–2DOF–PID controller design by 46.52%, and lower than 2DOF–PID, PID, and PI–1PD by 29.73%, 22.19%, and 9.68%, respectively. The frequency–channel ST is 150–180 s, whereas tie-line exchanges settled in the mid–150 s with visibly smoother profiles. These results indicate that Optimal–FL–2DOF–PID provides robust and efficient frequency regulation for multi-area systems under significant uncertainty, supporting deployment in future renewable energy-integrated power systems.