光伏并网逆变器的谐波电流抑制研究

Control Strategy for PV Grid-connected Inverter to Suppress Current Distortion

针对电压型三相光伏并网逆变器,分析了影响馈入电网电能质量的主要因素。为减小电网电压畸变对并网电流的影响,提出一种基于同步旋转坐标系的基波电流和谐波电流独立控制方案。同步旋转坐标系下,基波分量和谐波分量分别为直流量和频率为整数倍基频的交流量,采用比例积分(PI)控制器和比例谐振(PR)控制器对其进行独立控制,可实现输出功率调节和谐波抑制无静差控制。针对电网电压中的主要分量负序5次和正序7次谐波,利用瞬时功率理论检测5次、7次谐波电流,对其进行同步旋转坐标变换,5次和7次谐波转换为6次分量利用PR控制器对谐波电流进行补偿。设计一台100 kW的实验平台,验证了所提出的控制方案能有效抑制背景谐波对并网电流的影响。

The main factors that affecting the power quality fed into grid from voltage source inverter is analyzed.To suppress the current distortion,a control strategy of fundamental current and harmonics controlled separately is adopted. On the synchronous rotating coordinate,the fundamental component is direct value and the harmonic component is alternating value.Proportion-integral（PI） controller and proportion resonant（PR） controller are adopted to control the values above which can achieved output power adjustment and zero error control of harmonic restrain.As the main current harmonic in the grid are 5th and 7th,the instantaneous power method is adopted to detecting the current harmonics, the PR controller is used to compensate the current harmonic of 6th.A 100 kW platform is designed,and the proposed method is verified which can effectively suppress the influence from background harmonic to grid-connected current.