In microgrid, the presence of multiple renewable energy sources as power supplies, coupled with the influence of complex operating conditions, makes it challenging to ensure the output power quality. By analyzing various disturbance sources in power converters within the microgrid, active disturbance rejection repetitive control is proposed for a dual Buck converter. This method aims to suppress external disturbances and internal uncertainties in the system, thereby reducing harmonic content and improving the quality of the output power. A repetitive control component is utilized to suppress harmonics generated by high-frequency switches, improve the rejection ability of periodic disturbances, and overcome zero crossing distortion in the dual Buck converter; an extended state equation is established for dual Buck converters, which estimates and compensates for both internal state uncertainty and external non-repetitive disturbances in real-time. Then, the periodic delay which is the inherent drawbacks of the repetitive control is overcome, and the transient response and disturbance rejection capability of the system are improved effectively. The effectiveness of the proposed method is verified by MATLAB platform. The experiment results show that the proposed scheme obtains satisfied performance in alternating current (AC) voltage accuracy, dynamic performance, and disturbance resistance, especially in complex application scenarios such as load transients and nonlinear loads, the controller can reduce the output voltage fluctuations effectively, suppress waveform distortion, and ensure high-quality output voltage of the converter.