Small-Signal Modeling and Coordinated Optimal Control for an Embedded Heterogeneous MMC-MTDC System Considering AC/DC Bilateral Coupling

作者：Jiaqi Wu, Zhu Guo, Zhu Bo, Haoli Chen, Hao Lu, Yilin Zhong, Yuansheng Liang · 发表于：Electronics · 年份：2026 · DOI：10.3390/electronics15153287 · 研究领域：HVDC Systems and Fault Protection、Physics of Superconductivity and Magnetism、Microgrid Control and Optimization

Embedded Modular Multilevel Converter-Based Multi-Terminal Direct Current (MMC-MTDC) systems have become an important solution for enhancing transmission capacity and operational flexibility in urban hybrid AC/DC power grids. However, the coexistence of Grid-Following (GFL) and Grid-Forming (GFM) MMC stations introduces complex dynamic interactions through both AC and DC networks. Existing small-signal stability studies often neglect MMC internal dynamics, such as submodule capacitor voltage fluctuations and circulating current-related states, or simplify the AC network as an ideal voltage source, which may lead to inaccurate stability assessment and limited control parameter optimization performance. To address these issues, this paper proposes a coordinated small-signal stability enhancement strategy for an embedded heterogeneous MMC-MTDC system considering AC/DC bilateral coupling. First, a system-level full-order small-signal state-space model is established by incorporating the internal dynamics of both GFL-MMC and GFM-MMC stations, non-ideal AC networks, and DC transmission links. Then, eigenvalue analysis and participation factor-based sensitivity evaluation are performed to identify weakly damped oscillation modes and screen the key variables and control parameters associated with dominant oscillations. Furthermore, a quadratic performance index is constructed by weighting the sensitivities of key control parameters, and particle swarm optimization is employed to obta...