Adaptive backstepping droop controller design for multi-terminal high-voltage direct current systems

Xiaodong Zhao, Kang Li*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

23 Citations (Scopus)

Abstract

Wind power is one of the most developed renewable energy resources worldwide. To integrate offshore wind farms to onshore grids, the high-voltage direct current (HVDC) transmission cables interfaced with voltage source converters (VSCs) are considered to be a better solution than conventional approaches. Proper DC voltage indicates successive power transfer. To connect more than one onshore grid, the DC voltage droop control is one of the most popular methods to share the control burden between different terminals. However, the challenges are that small droop gains will cause voltage deviations, while higher droop gain settings will cause large oscillations. This study aims to enhance the performance of the traditional droop controller by considering the DC cable dynamics. Based on the backstepping control concept, DC cables are modelled with a series of capacitors and inductors. The final droop control law is deduced step-by-step from the original remote side. At each step the control error from the previous step is considered. Simulation results show that both the voltage deviations and oscillations can be effectively reduced using the proposed method. Further, power sharing between different terminals can be effectively simplified such that it correlates linearly with the droop gains, thus enabling simple yet accurate system operation and control.

Original languageEnglish
Pages (from-to)975-983
Number of pages9
JournalIET Generation, Transmission and Distribution
Volume9
Issue number10
DOIs
Publication statusPublished - Jul 2015

Keywords

  • HVDC power transmission
  • control system synthesis
  • wind power plants
  • power cables
  • HVDC power convertors
  • power transmission control
  • voltage control
  • adaptive backstepping droop controller design
  • multiterminal high-voltage direct current systems
  • wind power
  • renewable energy resources
  • offshore wind farms
  • HVDC transmission cables
  • voltage source converters
  • VSC
  • DC voltage
  • power transfer
  • onshore AC grid
  • DC grid
  • DC voltage droop control
  • voltage deviation
  • droop gain settings
  • traditional droop controller design
  • DC cable dynamics
  • backstepping control concept
  • capacitors
  • inductors
  • droop control law
  • control error
  • power sharing
  • system operation
  • OFFSHORE WIND FARMS
  • TRANSMISSION

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