Offshore Fixed Platforms (OFP) is a type of offshore platform used for the extraction of petroleum or gas; however, there is an essential need to use renewable energy sources in these systems due to the increasing demand for electricity in OFP power systems and to reduce fossil fuel consumption. This article offers a novel control technique for frequency regulation in an OFP Microgrid system based on fractional-order hybrid controllers. The proposed system is an OFP microgrid, which includes photovoltaics, wind turbines, an energy storage system, and a diesel generator, modelled in MATLAB / Simulink software. FOPDF(1+FOPI), FOPDF (1+PI), and PDF (1+PI) controllers were utilized to regulate the frequency of the investigated microgrid, with their coefficients adjusted using the meta-heuristic Slime Mould Algorithm (SMA). The strength of this method for optimizing the coefficients of intelligent controllers for placing in the secondary control loop, frequency control under various scenarios, and working conditions with uncertainties such as parametric changes and lack of proper access to renewable resources in different climatic conditions has also been evaluated. The ISTAE time-domain performance index is an objective function in the controllers' design process. ITAE and the IAE indicators are considered for assessing controllers' performance. The findings and assessments reveal the excellent performance of the suggested controller, and the superiority of the FOPDF(1+FOPI) controller based on the SMA for controlling the frequency of the OFP microgrid is proven. The efficiency of the suggested strategy has been established in terms of response speed, reduction of maximum Overshoot and maximum undershoot, and resistance to the uncertainty of parameters. The proposed controller has a quicker response speed than existing control techniques, and the response speed to fluctuations has been enhanced. Approximately 20 to 60 percent fluctuations in various situations have reduced maximum Overshoot and undershoot.