Distributed generations (DGs) have been increasingly employed in AC microgrids to provide carbon-free power supply. To coordinate multiple DGs, careful attention must be paid to the synchronization stability of their interfaced inverters. Otherwise, low-frequency oscillations and even loss of synchronism may occur and pose a great threat to the system. The conventional solutions towards this issue are to derive the microgrid state-space model and evaluate its stability based on the roots of the characteristic equation. However, tremendous efforts shall be spent on modeling as the number of DG increases. This paper provides an alternative way, which localizes the target of system synchronization stability into individual inverters. It is revealed and proven that microgrid synchronization stability can be guaranteed if all the inverters are designed to have passive synchronization behaviors. To fulfill this requirement and achieve a satisfactory phase margin, an auxiliary controller is designed to reshape frequency-power characteristics of inverters. Finally, case studies of a three-DG microgrid verify the theoretical findings as well as the effectiveness of the auxiliary controller.

中文翻译：

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电力电子接口分布式发电基于无源性的同步稳定性分析

分布式发电（DG）已越来越多地用于交流微电网中，以提供无碳电源。要协调多个DG，必须特别注意其连接的逆变器的同步稳定性。否则，可能会发生低频振荡甚至失去同步性，并对系统造成巨大威胁。解决该问题的常规方法是推导微电网状态空间模型，并基于特征方程的根来评估其稳定性。但是，随着DG数量的增加，必须在建模上花费大量的精力。本文提供了一种替代方法，该方法将系统同步稳定性的目标定位到各个逆变器中。揭示并证明，如果所有逆变器均设计为具有被动同步行为，则可以确保微电网同步稳定性。为了满足这一要求并获得令人满意的相位裕度，设计了一个辅助控制器来重塑逆变器的频率-功率特性。最后，一个三DG微电网的案例研究验证了理论发现以及辅助控制器的有效性。