Robust HHO-optimized fractional-order load frequency control for multi-area hybrid AC/DC microgrids with SMES coordination

A global focus grows on renewable energy harnessed for the development of Hybrid Microgrid Systems; these take meaningful, contemporary energy sources together into a unified system for reliability, efficiency, and sustainability. Power system stability, Load Frequency Control (LFC), and robustness are majorly affected by the stochastic and intermittent nature of renewable resources. Here, challenges in the two alternatives are handled by presenting the design of a Robust Fractional-Order Controller (RFOC), assisted by advanced optimization techniques of Genetic Algorithms (GA), Particle Swarm Optimization (PSO), and Harris Hawks Optimization (HHO). The RFOC proposed employing Fractional Order Proportional-Integral-Derivative (FOPID) controllers grants much more flexibility, precision, and adaptability for nonlinear dynamics management of the Hybrid Microgrids (HMGs). The study further provides extensive modelling of single and multi-area microgrid systems, including components like Superconducting Magnetic Energy Storage (SMES) systems for frequency control and integration of the renewables. While fractional-order PID controllers and metaheuristic optimization have been individually explored for LFC, their robust integration specifically for multi-area hybrid AC/DC microgrids with coordinated SMES operation remains largely unaddressed. The novelty of this work lies not in the FOPID structure itself, but in: (1) the systematic robust optimization of FOPID parameters using HHO for multi-area hybrid AC/DC microgrids with high renewable penetration; (2) coordinated SMES integration within the fractional-order LFC framework; and (3) unified stability assessment combining both time-domain and eigenvalue-based damping ratio analyses, an aspect often overlooked in existing studies. A performance evaluation in various scenarios such as sudden load changes; integration of renewable sources proves the superiority of stability and robustness of the HHO-FOPID controller in operation. Main indicators of performance such as frequency deviation minimization, eigenvalues, and damping ratio analyses showcase the efficacy of the proposed technique in the fast settling of the transients with minimum overshoots and sustained stability during disturbances. This work emphasizes the potential of futuristic fractional-order controllers in augmenting the reliability of modern power systems; thus, providing a roadmap to grid operators and energy stakeholders in nurturing power quality and renewable resource integration. The increasing penetration of Renewable Energy Sources (RES) in hybrid AC/DC microgrid systems introduces significant challenges related to load frequency regulation, system nonlinearity, and robustness against uncertainties arising from intermittent generation and load disturbances. Conventional integer-order controllers often exhibit limited performance under such highly dynamic operating conditions. To address these challenges, this paper presents a robust LFC strategy based on a FOPID controller optimally tuned using the HHO algorithm. The proposed controller, referred to as a RFOC, is coordinated with a SMES unit to enhance dynamic frequency response and disturbance rejection capability. Single-area and multi-area hybrid microgrid models incorporating RES are developed to evaluate the effectiveness of the proposed approach under various operating scenarios, including sudden load changes, load outages, and renewable energy integration. The performance of the RFOC is assessed using time-domain frequency deviation analysis and small-signal stability metrics such as eigenvalues and damping ratios. Simulation results demonstrate that the HHO tuned RFOC achieves reduced frequency deviations, faster settling times, and improved damping characteristics compared to other optimization based FOPID controllers, thereby ensuring robust and reliable operation of hybrid AC/DC microgrid systems.