This paper is concerned with the analysis of an instability phenomenon, known as limit cycle, in hybrid microgrids (HMGs). The rapid growth of distributed energy resources and their integration into existing distribution networks has opened a new era for electricity generation and distribution markets. The appearance of microgrids, both in the form of ac and dc, is the result of this integration. When both ac and dc microgrids (AC-MGs and DC-MGs) are in the vicinity of each other, they can be interconnected via ac-dc converters, also known as interlinking converters (ICs). Such a structure allows more efficient use of all resources in the system by enabling energy exchange between DC- and AC-MGs. In this paper, it is shown how the reactive power compensation method in IC leads to unstable operation of the HMG. Detailed analysis of this instability reveals that it is caused by a phenomenon known as limit cycle. By knowing the roots of instability, it is possible to eliminate it. Then we studied how the limit cycle that occurred is avoided by nonlinear control techniques support. The analytical studies are backed up by the simulation of a sample HMG.

中文翻译：

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混合微电网互联变流器无功发电过程中出现的极限环

本文涉及对混合微电网 (HMG) 中称为极限循环的不稳定现象的分析。分布式能源的快速增长及其与现有配电网络的整合，开启了发电和配电市场的新纪元。交流和直流两种形式的微电网的出现都是这种集成的结果。当 AC 和 DC 微电网（AC-MG 和 DC-MG）彼此靠近时，它们可以通过 AC-DC 转换器互连，也称为互连转换器 (IC)。这种结构通过实现 DC-MG 和 AC-MG 之间的能量交换，可以更有效地利用系统中的所有资源。在本文中，展示了 IC 中的无功功率补偿方法是如何导致 HMG 运行不稳定的。对这种不稳定性的详细分析表明，它是由称为极限环的现象引起的。通过了解不稳定的根源，就有可能消除它。然后我们研究了如何通过非线性控制技术的支持来避免出现的极限环。分析研究得到了样品 HMG 模拟的支持。