Generalized impedance-based AC/DC power system modeling for harmonic stability analysis

This paper presents a generalized impedance-based modeling framework for harmonic stability assessment due to converter interactions in hybrid AC/DC power systems, relying on detailed analytical frequency-dependent component models. The methodology proposed and derived in this paper enables the stability analysis of complete hybrid AC/DC power systems by explicitly accounting for the effect of both AC and DC systems, leaving out commonly applied simplifying assumptions for one of the two systems. The AC power system is modeled using a generalized transformation from three-phase variables in the ABC frame to a single dq-frame, enabling the representation of cables, overhead lines etc. while preserving inherent model complexities. The methodology is illustrated by presenting models for passive network components as well as for the modular multilevel converter (MMC), and by incorporating them in an example point-to-point High-Voltage Direct Current (HVDC) link.