Coordinated design of control parameters for improving interactive and internal stability of MMC-HVDC

Abstract

The interaction between the modular multilevel converter (MMC) and the power electronic systems leads to the interactive stability issues to the high-voltage dc transmission system (HVDC), including the dc-side interactive stability and ac-side interactive stability. Besides, the interactions among distributed submodules in MMC can cause the internal stability issue. All three types of stability issues pose challenges to the safe operation of the MMC-HVDC system. To guarantee the stable operation of MMC-HVDC system, this paper analyzes the internal and interactive stability of receiving-end MMC comprehensively and proposes a systematic procedure for coordinated design of control parameters. Firstly, a dynamic phasor model of receiving-end MMC considering the complete dynamics of the dc system is established to accurately capture the dynamic behavior of the receiving-end MMC. Subsequently, this model is used to evaluate the contributions and influence degree of different control parameters to the interactive and internal stability. Based on the analyses, a coordinated design method of multiple control parameters is developed to simultaneously improve the dc-side interactive stability, ac-side interactive stability, and internal stability. Finally, in the case study, the parameters range of multiple controllers is given following the coordinated design procedure. The effectiveness of the stability analyses and the feasibility of the designed parameter range is validated by the time-domain simulation in MATLAB/ Simulink.