Due to their salient features, modular multilevel converters (MMCs) are particularly suitable for a high-voltage direct current (HVDC) transmission system. Nevertheless, for an HVDC system, each phase of the MMC terminal may consist of several hundreds of submodules. This imposes a particular challenge in terms of steady-state simulation and modeling. Steady-state modeling is usually needed for determining the operating point for the MMC controller design and for predicting harmonics propagation in a power network. In this article, an efficient and accurate steady-state model for an MMC system with high-voltage levels is proposed. The model is based on a model reduction technique, namely residual-time restarting Krylov subspace method. As will be shown in this article, the proposed method is able to model various MMC systems. The results obtained from the proposed model are highly agreeable with those from PSCAD/EMTDC. Moreover, it will also be shown that the proposed method can drastically reduce the computation time for obtaining steady-state solutions.

中文翻译：

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高级模块化多电平转换器的精确加速稳态模型


由于其显着的特点，模块化多电平转换器（MMC）特别适合高压直流（HVDC）传输系统。然而，对于HVDC系统，MMC终端的每一相可能由数百个子模块组成。这对稳态仿真和建模提出了特殊的挑战。通常需要稳态建模来确定 MMC 控制器设计的工作点以及预测电力网络中的谐波传播。本文提出了一种适用于高电压 MMC 系统的高效且准确的稳态模型。该模型基于模型简化技术，即剩余时间重启 Krylov 子空间方法。正如本文所示，所提出的方法能够对各种 MMC 系统进行建模。从所提出的模型获得的结果与 PSCAD/EMTDC 的结果非常一致。此外，还将表明所提出的方法可以大大减少获得稳态解的计算时间。