CJEE

Chinese Journal of Electrical Engineering ›› 2019, Vol. 5 ›› Issue (1): 24-35.

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Direct Current Control Strategy of SVG Based on Dual Sequence dq Coordinates Under Asymmetric Load Condition*

Shicheng Zheng*, Zhuangzhuang Li, Menglin Cao   

  1. School of Electrical and information Engineering, Anhui University of Technology, Ma’anshan 243002 China
  • Online:2019-01-20 Published:2019-01-20
  • About author:Menglin Cao received his B.S. and M.S. degrees in electrical engineering respectively from Shanghai University of Electric Power, Shanghai, and Anhui University of Technology, Ma’anshan, China. In 2018, he joined the Sungrow Power Supply CO.,Ltd., Hefei, China, as a control software engineer.
    His current research interests include grid connected PV inverters, storage system and micro DC-grid.Zhuangzhuang Li received his B.S. and M.S. degrees in electrical engineering from Anhui University of Technology, Ma’anshan, China.
    His current research interests include power converters, DC microgrid and new energy power generation technology.
    Shicheng ZHENG received his Ph.D degree in electrical engineering from Hefei University of Technology（HFUT）, Hefei, China in 2005. In 2005, he joined the school of Electrical and Information at Anhui University of Technology to undertake research in the area of power electronics and power drive and he was appointed Lecturer in 2008. He is currently a Professor in the School of Electrical and Information Engineering, Anhui University of Technology.
    His current research interests include power converters, grid connected photovoltaic inverters, distributed power generation and power quality and so on.
    Professor Zheng is a Senior Member of the CPSS.
  • Supported by:
    zsc108@ahut.edu.cn

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Abstract: In the case of asymmetric loads of power grid, load currents are composed of four components: positive sequence active and reactive components and negative sequence active and reactive components that can pollute the power grid with harmonics and reactive power and interrupt the normal operation of power grid. Therefore, increasing numbers of static var generators (SVGs) are used to stabilize the power grid. In this study, a new type of current compensation control strategy of a three-phase three-wire SVG under an asymmetric load is proposed. According to the symmetric component method and dual dq synchronous transformation theory, the load currents are transformed into four components under dual dq coordinates. Each component is compensated separately by the SVG. Simultaneously, the proportional-limiter method is adopted to minimize the harmonics from the SVG by optimizing the waveform of the modulation wave and limiting its amplitude. Finally, the validity and feasibility of the control strategy are verified by simulation and experimental results.

Key words: Dual-dq transformation, proportional-limiter, positive and negative components, active and reactive components