Modular multilevel converters (MMCs) have become an attractive solution for large-scale renewable energy integration. However, the complex internal dynamics of MMCs introduce challenges to system stability. To address the internal-dynamics driven (IDD) instability and enhance system stability, this article develops an internal-dynamics-guided (IDG) stabilization framework. Firstly, the origin of IDD instability is identified through internal-dynamics impedance characterization of MMCs, revealing that the capacitive behavior of internal dynamics may interact with inductive systems, leading to system instability. Building upon this mechanistic insight, a stabilization-design principle is established that compensates the destabilizing components of internal dynamics through targeted reshaping of the internal-dynamics impedance, thereby addressing the instability at its origin. Based on this principle, a systematic stabilization controller design methodology is developed, in which the control architecture and parameters are analytically derived from converter internal dynamics rather than relying on system impedance identification. As a result, the proposed IDG stabilization framework inherently avoids reliance on exact grid impedance and enhances stabilization robustness against system condition variations. Experimental results obtained under multiple operating conditions validate the effectiveness of the IDG stabilization framework in enhancing the stability margin and extending the stable operating region of MMC-based systems.
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