The grid-voltage feedforward control is widely used in the grid-connected converter control ,because it can reduce the shock caused by the startup inrush current. However ,the voltage feedforward will cause the reduction of the system′s stability ,and even the instability. The mathematical model of the grid-connected converter in the weak grid was established ,and the robust stability of the converter with the traditional feedforward control in the weak grid was analyzed using the root locus and small gain theory. Owing to the poor robust stability of the traditional full-feedforward control ,the notch filter based feedforward control method was proposed. To realize the gain stabilization ,the notch filter was introduced to tailor the magnitude of the voltage around the cross-over frequency. Therefore ,the converter′s robust stability against the grid impedance variation could be improved. Finally , the prototype of the grid-connected converter was built ,the experimental results confirm the validity of the analysis and the proposed strategy.%由于电网电压前馈可减小启动电流对并网变流器的冲击,因此被广泛应用在并网变流器控制中.然而,在弱电网条件下电网电压前馈会导致系统稳定性下降,甚至出现不稳定.首先建立了弱电网条件下并网变流器的数学模型,并基于根轨迹和最小增益定理对弱电网条件下采用传统电网电压完全前馈时系统的鲁棒稳定性进行了分析.针对采用传统完全电网电压前馈时系统鲁棒稳定性较低的问题,提出了基于陷波器的改进前馈控制策略.通过引入陷波器对系统开环穿越频率附近的前馈电压进行幅值衰减,实现增益稳定,从而提高并网逆变器对电网阻抗的鲁棒稳定性.最后,搭建了并网变流器实验样机,实验结果证明了理论分析的正确性和所提控制策略的有效性.
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