The droop-free control for ac microgrids achieves active power sharing and frequency regulation by replacing the centralized secondary control and the primary-level droop mechanism by a cooperative distributed control strategy. This article analyses the performance of the droop-free control when an islanded microgrid suffers electrical and communication failures. The microgrid is modeled by two connected graphs corresponding to the electrical and communication networks. The considered failures leads to partitioned electrical/communication subgraphs that coexist within the microgrid. A closed-loop model integrating the power flow equations, the droop-free control, and the electrical and communication graphs is derived. The stability analysis identifies critical partitions where the microgrid is driven to the instability, and the steady-state analysis characterizes the equilibrium points when the partitioned microgrid remains stable. This article also provides a control strategy that is able to avoid the instability scenario. Selected experimental results on a low-scale laboratory microgrid illustrate the impact that failures have in system performance and the ability of the proposed control for confining the microgrid operation into a safe region.

中文翻译：

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电气和通信故障下孤岛微电网无下垂控制的有功功率共享和频率调节


交流微电网无下垂控制通过协作分布式控制策略取代集中式二次控制和初级下垂机制，实现有功功率共享和频率调节。本文分析了孤岛微电网发生电气和通信故障时无下垂控制的性能。微电网由对应于电力和通信网络的两个连接图建模。所考虑的故障会导致在微电网内共存的分区电气/通信子图。导出了集成潮流方程、无下垂控制以及电气和通信图的闭环模型。稳定性分析识别微电网陷入不稳定的关键分区，稳态分析描述分区微电网保持稳定时的平衡点。本文还提供了一种能够避免不稳定情况的控制策略。在小规模实验室微电网上选定的实验结果说明了故障对系统性能的影响以及所提出的控制将微电网运行限制在安全区域的能力。