Fractional Frequency Transmission System (FFTS) has gained significant attention in the offshore wind power industry by utilizing the Modular Multilevel Matrix Converter (M3C) as a power converter. However, the direct coupling of inputs and outputs operating at different frequencies within the M3C-FFTS presents substantial challenges for system modeling and control. Hence, this paper presents a novel M3C hybrid modeling method to effectively decouple the power frequency side from the fractional frequency side. The power of each sub-converter bridge arm is represented using αβο, enabling us to derive and calculate detailed mathematical expressions for each power term. This approach establishes a solid theoretical foundation for achieving M3C capacitor voltage balance control. Building upon the hybrid modeling, we propose a novel control strategy for the M3C-FFTS system, aimed at ensuring balanced input and output conditions. The efficacy of the proposed modeling method and control strategy is verified through simulation using MATLAB/Simulink. 

Fractional frequency power transmission,modular multilevel matrix converter (M3C),Differential-mode- common-mode decoupling,Capacitor voltage balance control