Interaction between damping characteristics and the initial‐stage short‐circuit current of MMC‐HVDC transmission systems

This paper studies the interaction between the damping characteristics and the initial-stage short-circuit current of modular multilevel converter based high voltage direct current (MMC-HVDC) transmission system. First, the MMCs' input-output characteristics are obtained through the operator approach, and the influences of both linear part and nonlinear part are analysed. Second, an input-output characteristics based short-circuit current calculation method is proposed. Third, an eigenvalue-based comprehensive index is proposed to evaluate the damping characteristics of the MMC-HVDC transmission system. Finally, the interaction between the damping characteristics and the initial-stage DC short-circuit current is analysed under different system parameters and DC system structures. The analysis results show that there is a negative correlation between the system damping characteristics and the average rising rate of the short-circuit current. The proposed index G can effectively evaluate the short-circuit current of MMC-HVDC and can provide guidance for the planning of DC system structure, the selection of operation mode and system parameters.