分数阶插入式前馈重复控制及单相并网逆变器应用

In order to address the problem that the control performance of the conventional plug-in repetitive controller (PRC) is degraded when the weak grid frequency fluctuates, a fractional-order plug-in feedforward repetitive control (FOPFRC) method based on the Farrow structure filter is proposed in this paper. Firstly, the feedforward repetitive control internal model structure is introduced to optimize the internal model of the PRC, which improves the robustness of the system against the grid frequency fluctuations. Secondly, the Farrow structure filter is used to approximate simultaneously the fractional-order delay caused by the grid frequency fluctuations, so that the resonant frequency of the feedforward repetitive control can track the grid frequency in real time, further improving the harmonics suppression performance of the control system when the grid frequency fluctuates. Finally, the stability analysis and controller parameters optimization design method of the FOPFRC system are given. The experimental results show that the proposed FOPFRC method has strong harmonics suppression capability and good dynamic performance under weak grid conditions such as grid voltage distortion, grid frequency fluctuations, and grid voltage dips.