针对柔直送出场景中，基于虚拟同步机（Virtual Synchronous Generator, VSG）的模块化多电平（Modular Multilevel Converter, MMC）现有阻抗建模不够精细、且未能系统揭示控制参数对系统特性影响规律的问题，本文开展VSG-MMC阻抗建模与稳定特性研究。首先，基于MMC多频率稳态谐波特性，建立包含电压扰动小信号与励磁模块的VSG-MMC交流侧完整序阻抗模型，明确虚拟惯量、虚拟阻尼、无功下垂积分系数三类核心参数对阻抗幅频、相频特性的差异化调控路径；其次，建立了VSG‑MMC的功率小信号模型的基础上，量化参数变化对系统特征值分布及系统动态性能的影响；最后，在Simulink中搭建仿真测试平台，验证了模型的可靠性，对比了不同短路比下VSG-MMC系统的稳定性，研究了VSG控制参数对MMC交流侧阻抗特性的调控规律，并结合参数变化对系统动态性能的影响，为VSG-MMC控制参数设计提供理论依据与参考。

Aiming at the problems that the existing impedance modeling of virtual synchronous generator (VSG) based modular multilevel converter (MMC) is not sufficiently accurate and fails to systematically reveal the influence of control parameters on system characteristics in the VSC-HVDC transmission scenario, this paper conducts research on impedance modeling and stability characteristics of VSG-MMC. Firstly, based on the multi-frequency steady-state harmonic characteristics of MMC, a complete sequence impedance model of the AC side of VSG-MMC including voltage disturbance small-signal and excitation module is established, and the differentiated regulation paths of three core parameters, namely virtual inertia, virtual damping and reactive power droop integral coefficient, on the amplitude-frequency and phase-frequency characteristics of impedance are clarified. Secondly, on the basis of establishing the power small-signal model of VSG-MMC, the influence of parameter variation on the system eigenvalue distribution and dynamic performance is quantified. Finally, a simulation test platform is built in Simulink to verify the reliability of the model, compare the stability of the VSG-MMC system under different short-circuit ratios, investigate the regulation law of VSG control parameters on the AC-side impedance characteristics of MMC, and provide theoretical basis and reference for the control parameter design of VSG-MMC combined with the influence of parameter variation on system dynamic performance.