基于无源控制的并网逆变器特定次谐波电流抑制方法

Selective harmonic current suppression method for grid-connected inverters based on passivity-based control

分布式新能源发电多并接于较弱的配电网,该地区电网电压谐波含量大。受电网电压谐波与开关特性的影响,并网逆变器的电流容易发生畸变现象,影响系统稳定性。为此,文中针对三相并网逆变器提出一种基于无源控制的特定次谐波电流抑制方法。首先建立三相并网逆变器的欧拉-拉格朗日(Euler-Lagrange,EL)数学模型,并设计电流环无源控制器;然后结合多重参考系(multiple reference frame,MRF)方法引入误差电压补偿环路,对谐波电流进行独立控制;最后搭建系统仿真模型,并与传统比例积分(proportional integral,PI)控制和无源控制进行对比仿真研究。仿真结果表明,所提控制方法在具有无源控制优点的同时能够有效抑制三相并网逆变器的谐波电流,提高并网电流的电能质量,降低滤波器的设计要求,提高并网逆变器的弱电网适应能力。

New energy power generation devices are mostly located in weak power grid areas,where the grid voltage harmonic content is high.Affected by the grid voltage harmonics and switching characteristics,the current of the grid-connected inverter is prone to distortion,which affects the system stability.To solve this problem,a selective harmonic current suppression method based on passivity-based control is proposed for three-phase grid-connected inverters in this paper.Firstly,the Euler-Lagrange(EL)mathematical model of the three-phase grid-connected inverter is established,and the current loop passivity-based controller is designed.Then,combined with the multiple reference frame(MRF)method,an error voltage compensation loop is introduced to independently control the harmonic current.Finally,a simulation model of the system is built and a comparative simulation study is performed with the conventional proportional integral(PI)control and passivity-based control.The simulation results show that the proposed control method which has the advantages of passivity-based control,can effectively suppress the harmonic current of the grid-connected inverter and reduce the design requirements of the filter,thus improving the adaptability of the grid-connected inverter to the weak grid.