Robust H∞ frequency control of deregulated power systems with high renewable penetration and uncertainties

The increasing penetration of renewable energy sources (RESs) in deregulated power systems (DPSs) introduces significant challenges for load frequency control due to reduced system inertia, stochastic power fluctuations, and market-driven power transactions. These factors degrade frequency stability and tie-line power regulation, making the design of robust control strategies essential for reliable system operation. Therefore, this paper proposes an optimized robust H-infinity ( H ∞ ) controller for a two-area DPS with integrated wind and photovoltaic generation. The proposed controller is designed to minimize the worst-case gain between external disturbances and system outputs, thereby ensuring robustness against uncertainties arising from fluctuating loads, variable renewable generation, and market-driven power transactions. To achieve optimal controller performance, the parameters of the H ∞ weighting functions are systematically tuned using the recently developed dandelion optimization (DO) algorithm. The effectiveness of DO is validated through comparative analysis against several well-established and recent metaheuristic optimization techniques. Moreover, to further demonstrate the effectiveness and robustness of the proposed control strategy, the optimized H ∞ controller is compared with the conventional proportional–integral–derivative (PID) controller and its fractional-order version. This comparison highlights the superior ability of the proposed controller to handle system uncertainties and high renewable penetration levels. Simulation studies demonstrate that the DO-optimized H ∞ controller achieves significantly smaller frequency deviations, improved tie-line power regulation, and faster dynamic responses across a wide range of operating scenarios, confirming its suitability as a robust solution for modern DPSs with high RES penetration.