Virtual Flux-Based Scheme for Passivity Enhancement in MMC-HVDC System

Inherent control delays pose significant challenges to the stability of the Modular multilevel converter-based high voltage direct current (MMC-HVDC) system, inducing the risk of high-frequency resonances (HFR). This paper provides the virtual flux-based passivity enhancement schemes to remove the influence of the time delay terms. The negative damping risks can be eliminated, improving the system's stability and safety. The impedance modeling and simulation results validate the effectiveness of the approach.