中文摘要：

三相四线制微源逆变器在不平衡系统中具有独特优势,因此可作为微电网中变流器拓扑.为了改善微电网系统离网运行工况下带不平衡负载时的供电质量,提出一种改进负序控制方法.基于对称分量法和叠加原理对三相微源逆变器在不平衡负载下产生三相输出电压不对称的机理进行系统分析,得到了输出电压正序、负序、零序分量不同的补偿特性.设计了一个简单可行的同步正/负序参考系控制器,有效地补偿了不平衡负载引起的微源逆变器输出电压畸变,保证了微源逆变器在不平衡负载下能维持三相平衡输出电压.最后通过仿真和实验验证了理论分析和所提控制方法的正确性.

英文摘要：

A three-phase four-line topology is used in microgrid converter topology because of its unique advantages in unbalanced networks.To improve the islanded-mode power quality of microgrid system under unbalance load condi- tions, a modified control strategy using decomposed sequence components is presented.The mechanism of asymmetric output voltage of inverter under unbalanced loads has been analyzed based on symmetrical component decomposing and superimpose theory.h is shown that positive,negative and zero sequence components of output voltage have different influence on the performance of compensation.A simple and feasible synchronous positive/negative reference system controller is proposed which can effectively compensate voltage distortion of the inverter power supply under unbalanced loads, thus, symmetric three-phase output voltages of microgrid inverter under unbalanced load can be ensured.Simulation and experiment verify the correctness of the theoretical analysis of the proposed control method.