Grid-forming power converters (GFMC) have been widely adopted in power systems as an attractive solution against the challenges imposed by the ever-increasing penetration of renewables. Despite its versatility, GFMC is employed only to provide islanded operation, grid regulations, and synthetic inertia. To further extend the use of GFMC in enhancing power system stability, this paper proposes a multi-rotor virtual machine (MRVM) controller to attenuate sub-synchronous oscillations. Driven by the formulation of a virtual synchronous machine (VSM), the proposed MRVM implements a VSM-based GFMC with several virtual rotors whose electromechanical characteristics can be individually adjusted to target specific oscillatory modes in the system. In this work, the MRVM’s working principle is described in detail and tuning guidelines are proposed to simplify the selection of control parameters by using frequency-domain techniques and the eigenvalue locus analyses. To validate the performance of the MRVM, an IEEE benchmark grid model is adopted namely, the three-machine-infinite-bus system. It is evident from the results that the MRVM (i) provides higher degrees of freedom when dealing with sub-synchronous oscillations, and (ii) outperforms conventional GFMC, especially in damping intra-area power oscillations.

中文翻译：

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用于阻尼次同步谐振的并网转换器的多转子虚拟机

电网形成电源转换器 (GFMC) 已被广泛应用于电力系统，作为应对可再生能源日益普及所带来的挑战的有吸引力的解决方案。尽管具有多功能性，GFMC 仅用于提供孤岛运行、电网调节和合成惯性。为了进一步扩展 GFMC 在增强电力系统稳定性方面的应用，本文提出了一种多转子虚拟机 (MRVM) 控制器来衰减次同步振荡。在虚拟同步机 (VSM) 的制定的驱动下，所提出的 MRVM 实现了基于 VSM 的 GFMC，该 GFMC 具有多个虚拟转子，其机电特性可以单独调整以针对系统中的特定振荡模式。在这项工作中，详细描述了 MRVM 的工作原理，并提出了调谐指南，以通过使用频域技术和特征值轨迹分析来简化控制参数的选择。为了验证 MRVM 的性能，采用了 IEEE 基准网格模型，即三机无限总线系统。从结果中可以明显看出，MRVM (i) 在处理次同步振荡时提供了更高的自由度，并且 (ii) 优于传统的 GFMC，尤其是在抑制区域内功率振荡方面。