Key technologies of three-terminal DC transmission system based on modular multilevel converter

Author

Yang, Xiaodong ; Zhao, Chengyong ; Hu, Jing ; Wang, Jing ; Yang, Liu

Author_Institution

Key Lab. of Power Syst. Protection & Dynamic Security Monitoring & Control under Minist. of Educ., North China Electr. Power Univ., Beijing, China

fYear

2011

fDate

6-9 July 2011

Firstpage

499

Lastpage

503

Abstract

A three-terminal DC transmission system based on modular multilevel converter (MMC) is developed to solve the problem of power supply for distributed islands or cities. The system, with flexible features, may generate high quality output voltage and reduce construction costs and power losses in the converter stations. However, the three-terminal DC system based on MMC faces more complex situations in operation and its control strategies. In this paper, the mathematic model of three-terminal DC system based on MMC is deduced. Then according to the structure of MMC, a method of carrier phase-shift SPWM is introduced. As the system-level control, the decoupling controller for three-terminal DC system based on MMC is designed. A multi-point DC voltage control strategy based on DC voltage error method, which doesn´t need communication between converter stations, is proposed to improve the system reliability. By simulation with PSCAD/EMTDC, the feasibility and effectiveness of the proposed model and control strategies are verified.

Keywords

DC transmission networks; power convertors; power transmission control; power transmission reliability; voltage control; DC voltage error method; MMC; PSCAD/EMTDC; carrier phase-shift SPWM; control strategies; decoupling controller; distributed islands; modular multilevel converter; power supply; system reliability; system-level control; three-terminal DC transmission system; HVDC transmission; Mathematical model; Power conversion; Power system stability; Reactive power; Voltage control; Modular Multilevel Converter (MMC); control strategy; multi-point DC voltage control; three-terminal DC transmission system;

fLanguage

English

Publisher

ieee

Conference_Titel

Electric Utility Deregulation and Restructuring and Power Technologies (DRPT), 2011 4th International Conference on

Conference_Location

Weihai, Shandong

Print_ISBN

978-1-4577-0364-5

Type

conf

DOI

10.1109/DRPT.2011.5993942

Filename

5993942