Parallel distributed generation (DG) can extract power from a renewable energy source and supply it to the grid, but the exposure of DG components, such as photovoltaic panels, to the natural environment results in DG-side earth faults and common earth circulating current (CECC) problems. This study proposes an improved topology and a common and differential (C&D) mode control strategy to enhance the earth fault tolerance in parallel DG systems. First, the effects of line resistances and input voltages on CECC are analyzed through a mathematical model, and the disadvantages of the conventional buck converter are identified. Second, an additional switch in a negative pole is designed for the application of the C&D control strategy. Specifically, common-mode algorithm control is used to inhibit CECC, and differential-mode control is applied to ensure current sharing accuracy. Third, an inertial element is added to the reference voltage to restore the bus voltage produced by the differential-mode control strategy. Lastly, an experiment is conducted to verify that the proposed control outperforms conventional control in various conditions.

中文翻译：

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基于拓扑改进和共差模控制策略的DG侧接地容错增强

并联分布式发电 (DG) 可以从可再生能源中提取电力并将其提供给电网，但是 DG 组件（例如光伏电池板）暴露在自然环境中会导致 DG 侧接地故障和公共接地环流（ CECC) 问题。本研究提出了一种改进的拓扑结构和一种共模和差动 (C&D) 模式控制策略，以提高并联 DG 系统的接地故障容错能力。首先，通过数学模型分析了线路电阻和输入电压对 CECC 的影响，并确定了传统降压转换器的缺点。其次，为C&D控制策略的应用设计了一个额外的负极开关。具体来说，共模算法控制用于抑制CECC，采用差模控制，保证均流精度。第三，在参考电压上增加一个惯性元件，以恢复差模控制策略产生的总线电压。最后，进行了实验以验证所提出的控制在各种条件下均优于传统控制。