三相光伏逆变器并网电流不平衡控制策略研究

摘要对三相并网逆变器的研究大多以理想电网作为基础。但是在一定的条件下电网会出现不平衡故障。此时三相并网逆变器将会受到影响,输出的并网电流会含有大量的谐波,从而电网会受到污染。更严重的情况则会导致并网逆变器不能正常工作,甚至损坏其他元器件。因此对三相并网逆变器并网发生不平衡故障时的控制策略进行研究是必不可少的。
本文首先对三相并网逆变器在电网平衡时的工作原理做详细研究,其次分析三相并网逆变器在电网不平衡时运行情况。基于上述工作提出三相并网逆变器在电网不平衡时的控制策略,包括正负序分量分离控制策略、比例谐振(PR)控制策略。正负序分量分离控制策略将不平衡的电压量分解成平衡的正序分量和负序分量,再对平衡的分量进行控制。其中此方法主要设计了 2倍频陷波器,且给出了 PI 控制器的参数表达式，然后通过两个器件完成对不平衡电网的控制。而PR 控制策略则是直接对不平衡电压量进行控制,无需分解成正负序分量，同时本文也对 PR 控制器的伯德图和频率响应做了深入研究。33643
关键词三相并网逆变器电网不平衡正负序分量
毕业论文设计说明书外文摘要
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
目   录
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.751com.cn/zidonghua/lunwen_30846.html