Unidirectional DC/DC modular multilevel converter for offshore windfarm with the control strategy based on stationary frame

• Main Authors: He Liu, Mohamed Dahidah, Ramasamy Thaiyal Naayagi, Matthew Armstrong, James Yu
• Format: Article
• Language: English
• Published: Wiley 2019-03-01
• Series: The Journal of Engineering
• Subjects: offshore installations; wind power plants; power generation control; invertors; DC-DC power convertors; HVDC power transmission; control system synthesis; rectifiers; power transformers; offshore windfarm; advanced unidirectional DC/DC modular multilevel converter; high-voltage direct current transmission system; single-phase MMC; series-connected rectifier modules; multiple medium frequency transformers; conventional dq control method; stationary reference frame
• Online Access: https://digital-library.theiet.org/content/journals/10.1049/joe.2018.8003
• ISSN: 2051-3305

This paper presents the design and control of an advanced unidirectional DC/DC modular multilevel converter (MMC) that facilitate the integration of off-shore windfarms with the high-voltage direct current (HVDC) transmission system. The proposed converter deploys a single-phase MMC inverter coupled with series-connected rectifier modules through multiple medium frequency transformers. Unlike the conventional dq control method, which involves multiple transformations, this paper also proposes a simple control strategy that directly acts on the AC output of the MMC, under the stationary reference frame.