Dynamic modeling of modular multilevel DC/DC converters for HVDC systems

Author

Kish, Gregory Joseph ; Holmes, Christopher ; Lehn, Peter

Author_Institution

Dept. of Electr. & Comput. Eng., Univ. of Toronto, Toronto, ON, Canada

fYear

2014

fDate

22-25 June 2014

Firstpage

1

Lastpage

7

Abstract

This paper presents the first dynamic model of the DC-MMC, a new class of modular multilevel single-stage dc/dc converters aptly suited for HVDC systems. A state-space model for a single string of the DC-MMC is developed and validated by comparing with time-domain simulation results from a comprehensive switched converter model. The developed averaged model is utilized to investigate submodule capacitor voltage balancing characteristics of the DC-MMC. In particular it is demonstrated that, unlike the dc/ac modular multilevel converter, direct ac modulation of the DC-MMC is not sufficient to keep capacitor voltages balanced. The developed model is also used to propose and validate a supplemental controller that suppresses unwanted second and third harmonic circulating ac currents within the DC-MMC.

Keywords

DC-DC power convertors; HVDC power convertors; harmonics suppression; power conversion harmonics; switching convertors; time-domain analysis; DC-AC modular multilevel converter; DC-MMC; HVDC systems; direct AC modulation; dynamic modeling; modular multilevel single-stage DC-DC converters; second harmonic circulating AC currents; state-space model; submodule capacitor voltage balancing characteristics; switched converter model; third harmonic circulating AC currents; time-domain simulation; Capacitors; Frequency modulation; Inductors; Integrated circuit modeling; Mathematical model; State-space methods; Switches;

fLanguage

English

Publisher

ieee

Conference_Titel

Control and Modeling for Power Electronics (COMPEL), 2014 IEEE 15th Workshop on

Conference_Location

Santander

Type

conf

DOI

10.1109/COMPEL.2014.6877167

Filename

6877167