Evaluation of half-bridge modular multilevel converter model for VSC-HVDC transient stability studies

This paper evaluates the modeling methods for half-bridge modular multilevel converter (HB-MMC) based voltage-sourced converter (VSC) HVDC system for electromechanical transient (RMS) program. At first, the electrical and control system representation of the HB-MMC system in RMS program is described. This RMS model is then simplified by neglecting the inner/current controller. Both detailed and simplified RMS models are then validated against an accurate electromagnetic (EMT) transient model in a point-to-point (PtP) transmission system with different AC network strength, power directions and dynamic events.