Selective Harmonic Repetitive Control can be widely used in grid-connected converters because of its effective tracking of harmonic signals and its universality to different harmonic frequencies. However, the performance of harmonic tracking deteriorates seriously when the power grid frequency fluctuates. In this regard, this paper proposes an New Structure Frequency Adaptive selective harmonics Repetition Control Simplifying the original structure, reducing the number of adaptive designed filters, and introducing a Farrow filter based on Newton's structure to achieve accurate approximation of fractional delay caused by grid frequency fluctuations. The overall complexity of the control system structure is low, and it can adapt to fluctuations in grid frequency only through fractional delay coefficients. Taking three-phase active power filtering as an example, it is verified that the proposed control strategy has good dynamic performance and excellent harmonic tracking ability under different frequency conditions.