  Optimizing operational set points for modular multilevel converters (MMCs) in
Multi-Terminal Direct Current (MTDC) transmission systems is crucial for
ensuring efficient power distribution and control. This paper presents an
enhanced Optimal Power Flow (OPF) model for MMC-MTDC systems, integrating a
novel adaptive voltage droop control strategy. The strategy aims to minimize
generation costs and DC voltage deviations while ensuring the stable operation
of the MTDC grid by dynamically adjusting the system operation points. The
modified Nordic 32 test system with an embedded 4-terminal DC grid is modeled
in Julia and the proposed control strategy is applied to the power model. The
results demonstrate the feasibility and effectiveness of the proposed droop
control strategy, affirming its potential value in enhancing the performance
and reliability of hybrid AC-DC power systems.
