Several drawbacks of the conventional and inverse droop control based decentralized techniques for islanded microgrids are being addressed actively, over the years by various researchers. One of the prominent issues is the inaccurate power sharing (reactive power in the conventional droop and real power in the inverse droop) among the distributed generators (DGs) due to the feeder/line impedances. Virtual impedance (VI) is a popular technique to overcome impedance mismatches but the challenge is in the setting of the appropriate value. This paper presents an adaptive decentralized technique for adjusting the virtual impedance in the controller of a DG, based on its output current, without the need of communication, extra sensors or network parameter/load estimations. The methodology is tested through simulations for a wide variety of cases including unbalanced, harmonic, constant power and induction motor loads, DG plug and play functionality and performance in larger networks (modified 13 and 33 bus systems) under meshed configurations. The range for parameter stability is verified through modelling and small signal eigenvalue analyses. Further, improved power sharing performances using the proposed scheme is validated through implementation on a laboratory experimental setup.

中文翻译：

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用于改善孤岛交流微电网逆变器间功率分配的自适应虚拟阻抗控制

多年来，各种研究人员正在积极解决用于孤岛微电网的基于传统和反向下垂控制的分散技术的几个缺点。突出的问题之一是由于馈线/线路阻抗，分布式发电机 (DG) 之间的功率分配不准确（常规下垂中的无功功率和反向下垂中的有功功率）。虚拟阻抗 (VI) 是克服阻抗不匹配的流行技术，但挑战在于设置适当的值。本文提出了一种自适应分散技术，用于根据其输出电流调整 DG 控制器中的虚拟阻抗，无需通信、额外的传感器或网络参数/负载估计。该方法通过模拟各种情况进行测试，包括不平衡、谐波、恒定功率和感应电机负载、DG 即插即用功能和网格配置下较大网络（修改后的 13 和 33 总线系统）中的性能。通过建模和小信号特征值分析来验证参数稳定性的范围。此外，通过在实验室实验装置上的实施，验证了使用所提出的方案改进的功率共享性能。