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Advanced Droop Control Scheme in Multi-terminal DC Transmission Systems

  • Che, Yanbo (Key Laboratory of Smart Grid of Ministry of Education, Tianjin University) ;
  • Zhou, Jinhuan (Key Laboratory of Smart Grid of Ministry of Education, Tianjin University) ;
  • Li, Wenxun (Key Laboratory of Smart Grid of Ministry of Education, Tianjin University) ;
  • Zhu, Jiebei (Department of System Operators, National Grid plc) ;
  • Hong, Chao (State Key Laboratory of HVDC, Electric Power Research Institute, CSG)
  • Received : 2017.08.28
  • Accepted : 2018.01.15
  • Published : 2018.05.01

Abstract

Droop control schemes have been widely employed in the control strategies for Multi-Terminal Direct Current (MTDC) system for its high reliability. Under the conventional DC voltage-active power droop control, the droop slope applies a proportional relationship between DC voltage error and active power error for power sharing. Due to the existence of DC network impedance and renewable resource fluctuation, there is inevitably a DC voltage deviation from the droop characteristic, which in turn results in inaccurate control of converter's power. To tackle this issue, a piecewise droop control with DC voltage dead band or active power dead band is implemented into controller design. Besides, an advanced droop control scheme with versatile function is proposed, which enables the converter to regulate DC voltage and AC voltage, control active and reactive power, get participated into frequency control, and feed passive network. The effectiveness of the proposed control method has been verified by simulation results.

Keywords

VSC;MTDC;Droop control;Power fluctuation;Frequency regulation;Dead band

Acknowledgement

Supported by : China Southern Power Grid

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