基于PR调节器的并网型逆变器谐波抑制策略

Control strategy for grid-connected inverter to suppress harmonics based on PR regulator

解决LCL型并网逆变器谐振问题的有效途径是采用电容电流反馈的有源阻尼法,比例谐振(PR)调节器因具有良好的准确性和抗干扰性能,比PI调节器更适于对并网电流控制,但电网电压背景谐波会使并网电能质量变差。提出了一种基于电网电压微分前馈和PR调节器相结合的双闭环控制策略,经过适当变换,电容电流内环等效为网侧电感电压微分反馈,电网电压前馈等效为比例前馈。仿真实验结果表明,基于电网电压微分前馈和PR调节器相结合的控制策略可以基本避免电网电压谐波影响并网电能质量,且该策略可以省去对三相电容电流的检测,在很大程度上节约了成本。

The active damping based on capacitor current feedback was an effective way to restrain the resonant peak caused by the LCL filter in the grid-connected inverters. Comparing with PI regulator, PR regulator had a better accuracy and robustness, it was more suitable for grid-current control, while the high frequency background harmonic of power grid could affect the stability of the grid-connected power quality. Therefore, the strategy of the grid-connected current dual-loop control was proposed based on grid voltage differential feedforward and PR regulator. After simplifying the block diagram, the capacitor current loop was equivalent to the inductor voltage differential feedback at the grid-side. The feed-forward of grid voltage was equivalent to the proportion feedforward. The simulation results show that the strategy of the grid-connected current dual-loop control based on grid voltage differential feedforward and PR regulator can basically restrain the influence of harmonics in grid voltage to grid power quality. What＇s more, the detection of the capacitor current could not be eliminated through using this strategy, and a large cost was saved.