The modular multilevel converter (MMC) can integrate distributed energy systems (DES), such as a battery energy storage system, to expand its functionalities and carry out multiple simultaneous tasks. However, a DES induces power imbalances within the MMC, which affects the operating currents and voltages of the converter. This phenomenon has been partially covered in recent works, but an analytical analysis has not yet been carried out to see the behavior and implications in different MMC-DES applications. This article introduces a novel analytical analysis of the power imbalances between MMC clusters. It pioneers the development of general equations and imbalance capability metrics, enabling the assessment of maximum currents and voltages supported by the MMC clusters. The developed tools allow the evaluation of any MMC-DES application regarding the current and voltage rating requirements of MMC clusters. The analysis shows that the MMC operating mode can substantially restrain or enlarge its imbalance capacity, affecting its suitability for different DES applications. While it needs around 33% current overrating in the worst imbalances, under some operating modes it can reach most imbalances without requiring current overrating. The ac compensation mode is much more capable of achieving imbalances than the dc compensation mode, reaching 88.37% and 16.74% of the imbalance points, respectively, without requiring any overrating.

中文翻译：

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分布式能源系统模块化多电平变流器功率不平衡分析

模块化多电平转换器（MMC）可以集成分布式能源系统（DES），例如电池储能系统，以扩展其功能并同时执行多个任务。然而，DES 会引起 MMC 内的功率不平衡，从而影响转换器的工作电流和电压。最近的工作已部分涵盖这种现象，但尚未进行分析分析以了解不同 MMC-DES 应用中的行为和影响。本文介绍了一种针对 MMC 集群之间功率不平衡的新颖分析方法。它率先开发了一般方程和不平衡能力指标，从而能够评估 MMC 集群支持的最大电流和电压。所开发的工具可以根据 MMC 集群的电流和电压额定值要求评估任何 MMC-DES 应用。分析表明，MMC工作模式会显着抑制或放大其不平衡能力，影响其对不同DES应用的适用性。虽然在最严重的不平衡情况下需要大约 33% 的电流高额定值，但在某些工作模式下，它可以在不需要电流高额定值的情况下达到大多数不平衡状态。交流补偿模式比直流补偿模式更能实现不平衡点，分别达到不平衡点的 88.37% 和 16.74%，而无需任何高额定值。