This article proposes a novel bipolar-type dc system suitable for both distribution and transmission systems based on modular multilevel series/parallel converters (MMSPCs). The system features decoupled operations of each pole of the bipolar system, being able to operate in both asymmetrical and regenerative modes. This enables two independent dc systems by using a single grid-tied converter. The MMSPC is based on a three-switch cell configuration and enables a simple balancing mechanism in combination with a wide range of output voltage frequencies. The simple balancing mechanism is the key to enable the dc operation and lead to simpler scalability for different voltage levels. Theoretical studies and experimental results are provided to verify and characterize the proposed system.

中文翻译：

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用于双极性直流配电和传输的模块化多级串联/并联转换器

本文提出了一种新颖的双极型直流系统，该系统适用于基于模块化多级串联/并联转换器（MMSPC）的配电系统和输电系统。该系统具有双极系统每个极的解耦操作，能够以非对称和再生模式运行。通过使用单个并网转换器，可以启用两个独立的直流系统。MMSPC基于三开关单元配置，并结合了广泛的输出电压频率，可实现简单的平衡机制。简单的平衡机制是实现直流工作并在不同电压水平下实现更简单可扩展性的关键。提供理论研究和实验结果以验证和表征所提出的系统。