: Conventional integer-order delay repetitive control with limited resonant bandwidth and open-loop gain would provide increased control error and degraded dynamic performance when the grid frequency fluctuates. To overcome this limitation and enhance the dynamic response, combining feedforward dual-mode repetitive control and proportional gain in parallel, a fractional-order delay feedforward dual-mode repetitive control (FD-FDRC) scheme for grid-tied inverters was proposed. Due to the feedforward link in the repetitive control internal model, the improved internal model structure can provide a higher open-loop gain and wider resonance bandwidth at harmonic frequencies, thus, a faster error convergence rate, a higher tracking accuracy, and enhanced performance in harmonic suppression were achieved. Moreover, a Farrow-structure filter was utilized for accurate fractional-order delay approximation while avoiding complex coefficient computations, significantly reducing the computational time. The stability analysis and detailed parameters design for the FD-FDRC system were presented. Finally, the extensive experiment results validate both the feasibility and enhanced control performance of the proposed approach when the grid frequency fluctuates.