The hybrid droop and master-slave structure studied in existing work complements the advantages of droop control and master-slave control, at the cost of frequency and voltage deviations in microgrids. To eliminate these deviations and maintain accurate power sharing among distributed generators, this paper proposes a decentralized secondary control method based on mode switching, where the secondary controller switches among three modes. In the first mode, a feedback strategy is applied to maintain accurate power sharing among slave distributed generators, and then the load demand is estimated and redistributed among distributed generators to calculate new secondary control commands in the second mode, which are further updated in the third mode to eliminate frequency and point-of-common-coupling bus voltage deviations. The proposed method is communication-free and is able to eliminate the influence of triggering delay among slave distributed generators during the mode switching. The effectiveness of the proposed method is verified through hardware experiments.

中文翻译：

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基于模式切换的混合下垂主从结构微电网分散二次控制

在现有工作中研究的混合下垂和主从结构补充了下垂控制和主从控制的优点，但以微电网中的频率和电压偏差为代价。为了消除这些偏差并保持分布式发电机之间的精确功率共享，本文提出了一种基于模式切换的分散式二次控制方法，其中二次控制器在三种模式之间切换。在第一种模式中，应用反馈策略以保持从属分布式发电机之间准确的功率共享，然后在分布式发电机之间估计和重新分配负载需求，以在第二种模式下计算新的次级控制命令，在第三种模式下进一步更新模式以消除频率和公共耦合点总线电压偏差。所提出的方法是免通信的，并且能够消除模式切换期间从分布式发电机之间触发延迟的影响。通过硬件实验验证了所提方法的有效性。