非理想电网下并网逆变器直流分量检测及抑制方法

DETECTING AND SUPRRESSING METHOD FOR DC INJECTION OF GRID-CONNECTED INVERTER UNDER NONIDEAL GRID CONDITION

为抑制非理想电网条件下光伏并网发电系统中并网逆变器的并网电流直流分量,提出一种基于直流侧母线电压纹波分析的间接检测及补偿方法。首先建立并网逆变器数学模型,分析并网电流直流分量产生机理;然后研究并网电流与母线纹波电压的关系,得出在非理想电网条件下,并网电流直流分量可等效为母线纹波电压的奇倍频纹波分量的结论;通过分段积分一个电网周期的母线电压求得并网电流直流分量解析式,以该式为反馈量加入系统控制环节可有效抑制并网电流直流分量的产生。最后通过仿真和实验验证所提方法的可靠性。

In order to suppress the DC component of grid-connected current in inverter of PV grid-connected power generation system under nonideal grid condition,an indirect detection and compensation method based on DC side bus voltage ripple analysis is proposed.Firstly,the mathematical model of the grid-connected inverter is established,and the generation mechanism of the DC component of the grid-connected current is analyzed.Then the relationship between the grid-connected current and the busbar ripple voltage is studied,and it is concluded that the DC component of the gridconnected current can be equivalent to the odd-frequency ripple component of the busbar ripple voltage under non-ideal grid conditions.Obtaining the DC component analytic of the grid-connected current by segmentally integrating the bus voltage of a grid cycle,adding the formula as feedback amount into the system control link can effectively suppress the generation of DC component of grid-connected current.Finally,the reliability of the proposed method is verified by simulation and experiment.