## 三相光伏逆变器并网电流不平衡控制策略研究

Title      researches of three-phase grid-connected inverter
Abstract
Most researches of three-phase grid-connected inverter are based on the ideal grid. However, the power grid will appear unbalanced fault in exceptional circumstances. At this time, the three-phase grid inverter will be affected. The output current harmonic content is high. The grid will be polluted. And in severe cases,grid-connected inverter will not work, even damage to the components. Therefore it is essential for the study of the three-phase grid-connected inverter control when grid unbalanced fault occurs.

Firstly, the detailed study of the three-phase grid-connected inverter working principle under the balanced grid has been done in this paper. Secondly, in-depth research of the three-phase inverter under the unbalanced grid has been discussed.Finally, the control strategies of three-phase grid-connected inverter under unbalanced gird are proposed, including the positive and negative sequence component separation control algorithm, the proportion and resonance control (PR) algorithm control algorithm. Unbalanced voltage is decomposed into the balanced positive-sequence component and negative-sequence component. So the unbalanced grid is equivalent to balanced grid,which makes the control algorithm become simply. The notch filter is designed and PI controller parameter expressions are given in the paper. Bode plots and frequency responses of the PR controller has been analyzed carefully.
Keywords  The three-phase grid inverter   unbalanced grid   positive and negative sequence component

1  引言    1
1.1  光伏发电系统概述    1
1.2  光伏发电系统的国内外发展情况    1
1.3  电网不平衡时三相逆变器控制技术研究现状    2
2  电网不平衡时三相光伏并网逆变器数学建模    3
2.1  三相正序负序零序分量定义    3
2.2  对称分量法    4
2.3  三相光伏并网逆变器数学建模    5
2.3.1  三相并网逆变器的一般数学模型    5
2.3.2  Clarke坐标变换    6

2.3.3  Park坐标变换    7
2.3.4  两相旋转坐标系中电网不平衡三相并网逆变器模型    8
3  电网不平衡时三相光伏并网逆变器的控制策略    10 三相光伏逆变器并网电流不平衡控制策略研究:http://www.lwfree.cn/zidonghua/20190308/30846.html
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