Dynamic phasor modeling of Modular Multi-level Converters

This paper presents the application of dynamic phasors to analyse small signal stability of a Modular Multilevel Converter (MMC) which can be used as a terminal of HVDC transmission system. Unlike a model based on the D-Q transformation, a dynamic phasor model is amenable for eigen-analysis after linearization, as it yields a time invariant model. The dynamic phasor model also includes the control system of the MMC which is based on D-Q variables. Time domain simulation is carried out to validate the model, and it is shown that the model can predict critical gains for instability.