一种提高变流器弱电网适应能力的全通前馈方法

All-pass Feedforward Method for Improving the Adaptability of Converter to Weak Grid

弱电网下电网阻抗会严重影响并网变流器的稳定性,首先建立了含有电网电压前馈时并网变流器的阻抗模型,根据阻抗比判据分析了并网变流器在弱电网下的稳定性。针对传统电网电压前馈下并网变流器对弱电网适应能力较低的问题,提出了一种基于全通滤波的电网电压前馈方法,并分析了全通滤波器参数对系统弱电网适应能力的影响。理论分析表明基于全通滤波的电网电压前馈控制方法可显著提高并网变流器的弱电网适应能力。最后,搭建了系统仿真模型和实验样机,仿真和实验结果验证了理论分析的正确性和所提控制策略的有效性。

The grid impedance will seriously affect the stability of grid-connected converters in weak grid.First,the impedance model of a grid-connected converter with grid voltage feedforward is established in this paper,and the stability of the grid-connected converter in weak grid is analyzed according to the impedance ratio criterion.Then,aimed at the problem of low adaptability of grid-connected converter to weak grid with the traditional grid voltage feedforward,a grid voltage feedforward method based on all-pass filter is proposed,and the influence of all-pass filter parameters on the systemf s adaptability to weak grid is analyzed.The result of theoretical analysis shows that the grid voltage feedforward control method based on all-pass filter can significantly improve the adaptability of grid-connected converter to weak grid.Finally,a simulation model and an experimental prototype were built,and simulation and experimental results verified the correctness of the theoretical analysis and the efiectiveness of the proposed control strategy.