Stability Analysis of a Hybrid Modular Multilevel Voltage Source Converter

Abstract

This paper presents a linearized state-space model of the hybrid cascaded modular multilevel voltage source converter. The developed model is validated against a detailed non-linear Electromagnetic Transient (EMT) simulation model. The impact of the ac system strength on the performance of the converter is investigated for moderately strong and weak systems. An eigenvalue analysis is conducted for both scenarios, with focus on the oscillatory modes present in the system in order to evaluate the stability constraints of the converter when connected to ac networks of different strengths.