A hybrid microgrid has numerous decentralised control loops. Therefore, coordination among hybrid microgrid subsystems with desired performance is essential. This study presents a practical control approach for efficient tuning of proportional-integral (PI) controllers and leads compensators in islanded hybrid microgrids. This method is based on the frequency response characteristic and root-locus trajectory. It is used to minimise the frequency deviations of an AC hybrid microgrid. The presented well-tuned controllers are tuned based on droop mechanism, and coordination among hybrid microgrid subsystems with desired damping coefficient and stability margin. Then, the system performance is analysed under several disturbances. The results are compared with PI controllers tuned by Ziegler-Nichols method. As well, the robustness of the proposed approach in a wide range of parameter changes is investigated. Eigenvalue analysis and simulation results show that the minimum frequency deviations and desired relative stability of the hybrid microgrid subsystems are achieved by the proposed controllers. To show generality and efficiency of the proposed approach, the presented method is applied to a different hybrid microgrid model used in the literature. For this purpose, in order to control the frequency deviations in the stand-alone mode, presented well-tuned controller is compared with intelligent fuzzy and particle swarm optimisation-fuzzy controllers. Nomenclature K P proportional coefficient K I integral coefficient K D derivative coefficient T o lead compensator zero ζ damping coefficient ω n natural frequency ω c gain crossover frequency

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<p style='text-indent:20px;'>The fuel cell (FC) is a new technology for large-scale power generation. Providing of fast and sufficient air concentration in the FC cathode is a key to prevent the oxygen starvation and extend the life cycle of the FC. The proton exchange membrane fuel cell (PEMFC) parameter variations and output current disturbances can significantly influence on the airflow subsystem performance. For this purpose, this paper addresses the robust airflow control synthesis of the PEMFC based on the <inline-formula><tex-math id="M3">\begin{document}$ \mu $\end{document}</tex-math></inline-formula> and <inline-formula><tex-math id="M4">\begin{document}$ H_\infty $\end{document}</tex-math></inline-formula> control techniques. The presented advanced controllers are designed to regulate the oxygen concentration in the FC cathode on the desired value. Such robust controllers are tuned to guarantee PEMFC performance against parameter variations and output current disturbances. Then, the obtained results are compared with the optimal PID controller tuned by the well-known internal model control (IMC) method. Simulation results show that in comparison of the IMC-based PID controller, the applied robust control methodologies are more effective. The designed <inline-formula><tex-math id="M5">\begin{document}$ \mu $\end{document}</tex-math></inline-formula> and <inline-formula><tex-math id="M6">\begin{document}$ H_\infty $\end{document}</tex-math></inline-formula> controllers efficiently provide the required airflow of the PEMFC on the desired value, and avoid the oxygen starvation. Furthermore, due to the structured type of uncertainties, the <inline-formula><tex-math id="M7">\begin{document}$ \mu $\end{document}</tex-math></inline-formula> controller keeps the airflow on the desired value quite better than the <inline-formula><tex-math id="M8">\begin{document}$ H_\infty $\end{document}</tex-math></inline-formula> controller.</p>