A low-voltage microgrid is naturally three-phase unbalance due to the connection of unbalanced loads. Voltage unbalance compensation (VUC) strategies of inverters have been proposed to compensate the voltage unbalance on the point of common coupling. However, the small-signal analysis of these VUC strategies has not been investigated in a microgrid with multiple inverters, which is due to the difficulty of the state-space modeling for unbalanced microgrids. This lack of discussion may result in a poor performance of the microgrid when the parameters of VUCs are not well designed. To investigate the dynamic behavior of the unbalanced microgrid with VUC strategies, this article develops a detailed state-space model for an unbalanced microgrid using the dynamic phasor method. Then, based on the developed model, small-signal analysis is carried out to investigate the effect of the VUC control on the dynamic behavior of a microgrid. It is found that a poor design of the VUC controllers may result in the instability of the microgrid. Finally, an improved compensation method with better compensation performance is proposed. Experimental results are used to validate the effectiveness of the proposed method.

中文翻译：

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基于小信号分析的孤岛微电网不平衡电压补偿性能改进

由于连接不平衡负载，低压微电网自然会出现三相不平衡。已经提出了逆变器的电压不平衡补偿（VUC）策略来补偿公共耦合点上的电压不平衡。然而，这些 VUC 策略的小信号分析尚未在具有多个逆变器的微电网中进行研究，这是由于不平衡微电网的状态空间建模困难。当 VUC 的参数设计不当时，缺乏讨论可能会导致微电网性能不佳。为了使用 VUC 策略研究不平衡微电网的动态行为，本文使用动态相量方法为不平衡微电网开发了一个详细的状态空间模型。然后，基于开发的模型，进行小信号分析以研究 VUC 控制对微电网动态行为的影响。发现 VUC 控制器设计不当可能会导致微电网的不稳定。最后，提出了一种补偿性能更好的改进补偿方法。实验结果用于验证所提出方法的有效性。