Control and modulation strategies for modular multilevel converter based HVDC system

Author

Guan, Minyuan ; Xu, Zheng ; Chen, Hairong

Author_Institution

Coll. of Electr. Eng., Zhejiang Univ., Hangzhou, China

fYear

2011

fDate

7-10 Nov. 2011

Firstpage

849

Lastpage

854

Abstract

The modular multilevel converter (MMC) is a new kind of voltage source converter (VSC) with a high number of voltage levels and considered to be suitable for HVDC transmission. Based on circuit configuration and operation mechanism, this paper presents an mathematical model of MMC. Then the vector control strategy widely used in two-level VSC is applied to the control of MMC. Due to modular structure and cascaded connections, a very high number of voltage levels is obtained by MMC in HVDC applications, for which the nearest level modulation (NLM) become feasible. A combination of NLM and optimized capacitor voltage balancing control is presented to reduce the switching frequency as well as the switching losses of power semiconductors. Time-domain simulation performed in PSCAD/EMTDC shows that the control and modulation methods provide good steady-state and dynamic system performance and significantly reduce the switching frequency of power semiconductors.

Keywords

HVDC power convertors; power semiconductor devices; HVDC system; PSCAD-EMTDC; circuit configuration; modular multilevel converter; nearest level modulation; optimized capacitor voltage balancing control; power semiconductors; switching losses; time-domain simulation; vector control strategy; voltage source converter; Capacitors; Modulation; Power conversion; Reactive power; Switches; Switching frequency; Voltage control;

fLanguage

English

Publisher

ieee

Conference_Titel

IECON 2011 - 37th Annual Conference on IEEE Industrial Electronics Society

Conference_Location

Melbourne, VIC

ISSN

1553-572X

Print_ISBN

978-1-61284-969-0

Type

conf

DOI

10.1109/IECON.2011.6119421

Filename

6119421