微网逆变器的不平衡电压补偿策略

发布时间：2018-05-11 07:45

本文选题：微电网 + 负序　；参考：《中国电机工程学报》2015年19期

【摘要】：对于孤岛模式下运行的三相微电网系统,不平衡负载的应用不仅导致负序电流的无序分配,而且将引起微电网母线电压的不平衡。为了补偿母线不平衡电压,提高负载电流分配效果,提出一种逆变器电压控制策略。首先推导同步旋转坐标下控制器到静止坐标系的通用等效变换表达式,接着分析整个闭环控制系统的频域特性。由于所提电压控制策略中基波正负序电压控制支路相互之间独立解耦,因此可简化虚拟阻抗的设计,在不需要正负序分量分离的前提下,可分别引入虚拟复合阻抗来控制逆变器的基波正负序输出阻抗,通过引入正序虚拟阻抗来改善感性线路阻抗环境下的逆变器基波正序功率分配效果,通过引入负序虚拟阻抗来补偿负序电流在线路阻抗上的电压降落,改善微电网电压的不平衡度,同时减小负序环流。最后通过仿真和实验结果验证了所提方法的正确性和有效性。
[Abstract]:For the three-phase microgrid system operating in isolated island mode, the application of unbalanced load not only leads to the disordered distribution of negative sequence current, but also leads to the imbalance of bus voltage in microgrid. In order to compensate the unbalanced bus voltage and improve the load current distribution, a voltage control strategy for inverter is proposed. The general equivalent transformation expression from the controller to the stationary coordinate system in synchronous rotation coordinates is derived, and then the frequency-domain characteristics of the whole closed-loop control system are analyzed. Because the fundamental positive and negative sequence voltage control branches are decoupled independently from each other in the proposed voltage control strategy, the design of virtual impedance can be simplified, without the need for the separation of positive and negative sequence components. The virtual composite impedance can be introduced to control the output impedance of the inverter, and the positive sequence virtual impedance can be introduced to improve the power distribution effect of the inverter in the environment of inductive line impedance. The negative sequence virtual impedance is introduced to compensate the voltage drop of the negative sequence current on the line impedance to improve the voltage imbalance of the microgrid and to reduce the negative sequence circulation. Finally, the correctness and validity of the proposed method are verified by simulation and experimental results.
【作者单位】：国家电能变换与控制工程技术研究中心(湖南大学);
【基金】：国家自然科学基金重点项目(51237003)~~
【分类号】：TM464

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