The possibility of operating distributed generation (DG) in islanded mode brings several benefits but still faces some problems, especially related to the transition from a grid-connected to an islanded operating condition. When connected to the main grid, DG units operate in PQ mode. During this transition, their controls must be changed to regulate frequency and voltage. The delay for islanding detection, associated with abrupt changes in the control references, may result in large and detrimental transients. This paper proposes a new control structure for a distributed synchronous generator (DSG) to allow a smooth transition from the grid-connected to the islanded operation mode. The proposed control structure uses a compensation loop that was conceived based on the main ideas of the anti-windup bumpless transfer (AWBT) theory (although it is not, strictly speaking, an AWBT controller). The results show that the proposed structure ensures smaller excursions of the DSG variables during the transition and, therefore, the possibility of a successful formation of the islanded system is extended to a wider range of operating conditions. Moreover, with the proposed control, the success of this transition does not depend on the islanding detection time, which is the main contribution of this paper.

中文翻译：

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分布式同步发电机从并网到孤岛运行平稳转换的控制结构

在孤岛模式下运行分布式发电 (DG) 的可能性带来了若干好处，但仍面临一些问题，尤其是与从并网到孤岛运行条件的过渡相关的问题。当连接到主​​电网时，DG 装置在 PQ 模式下运行。在此过渡期间，必须更改其控制以调节频率和电压。孤岛检测的延迟与控制参考的突然变化相关联，可能会导致大而有害的瞬变。本文为分布式同步发电机 (DSG) 提出了一种新的控制结构，以实现从并网运行模式到孤岛运行模式的平滑过渡。所提议的控制结构使用基于抗饱和无扰动传输 (AWBT) 理论的主要思想构想的补偿回路（尽管严格来说它不是 AWBT 控制器）。结果表明，所提出的结构确保在过渡期间 DSG 变量的偏移更小，因此，成功形成孤岛系统的可能性扩展到更广泛的操作条件。此外，使用所提出的控制，这种转换的成功不依赖于孤岛检测时间，这是本文的主要贡献。成功形成孤岛系统的可能性扩展到更广泛的操作条件。此外，使用所提出的控制，这种转换的成功不依赖于孤岛检测时间，这是本文的主要贡献。成功形成孤岛系统的可能性扩展到更广泛的操作条件。此外，使用所提出的控制，这种转换的成功不依赖于孤岛检测时间，这是本文的主要贡献。