Multi-terminal DC transmission systems for connecting large offshore wind farms

This paper describes the use of voltage source converter (VSC) based, multi-terminal (MT) HVDC transmission system technology for connecting large doubly-fed induction generator (DFIG) based wind farms, over long distance. The operational principles of the proposed system are described and control strategies for coordinating various grid side converters are proposed, to ensure smooth system operation and power sharing between various AC networks. DC voltage control and DC droop characteristics are implemented for the grid side VSC which transmit wind farm generated power to AC grids. PSCAD/EMTDC simulations for a four-terminal DC system for connecting two wind farms to two different AC networks are presented to demonstrate robust performance during wind speed and power variations, and large disturbances caused by the trip of one of the wind farms.

[1]  P.J. Tavner,et al.  Coordinated control of an HVDC link and doubly fed induction generators in a large offshore wind farm , 2006, IEEE Transactions on Power Delivery.

[2]  Lie Xu,et al.  Grid connection of large offshore wind farms using HVDC , 2006 .

[3]  Boon-Teck Ooi,et al.  Premium quality power park based on multi-terminal HVDC , 2005, IEEE Transactions on Power Delivery.

[4]  Boon-Teck Ooi,et al.  Premium quality power park based on multi-terminal HVDC , 2005 .

[5]  P. Cartwright,et al.  VSC transmission operating under unbalanced AC conditions - analysis and control design , 2005, IEEE Transactions on Power Delivery.

[6]  Boon-Teck Ooi,et al.  Multiterminal LVDC system for optimal acquisition of power in wind-farm using induction generators , 2002 .

[7]  B. T. Ooi,et al.  Optimal Acquisition and Aggregation of Offshore Wind Power by Multiterminal Voltage-Source HVdc , 2002, IEEE Power Engineering Review.

[8]  X.I. Koutiva,et al.  Optimal integration of an offshore wind farm to a weak AC grid , 2006, IEEE Transactions on Power Delivery.

[9]  R. W. De Doncker,et al.  Doubly fed induction generator systems for wind turbines , 2002 .

[10]  G. Joos,et al.  Multi-terminal DC (MTDC) system for wind farms powered by doubly-fed induction generators (DFIGs) , 2004, 2004 IEEE 35th Annual Power Electronics Specialists Conference (IEEE Cat. No.04CH37551).

[11]  Liangzhong Yao,et al.  Grid Integration of Large DFIG-Based Wind Farms Using VSC Transmission , 2007, IEEE Transactions on Power Systems.

[12]  Abdelkrim Benchaib,et al.  Analysis of a robust DC-bus voltage control system for a VSC transmission scheme , 2001 .

[13]  Lie Xu,et al.  HVDC transmission for large offshore wind farms , 2002 .

[14]  Lie Xu,et al.  HVDC transmission for large offshore windfarms , 2001 .