Fault current contribution of DFIG under unsymmetrical fault

In this paper, the transient characteristics of double-fed induction generator (DFIG) are analyzed. Based on this, the fault current contribution of DFIG with and without crowbar are compared. Comparison result shows that fault current of DFIG under different ride-through conditions differs widely from each other. Under unsymmetrical fault, the DFIG with a crowbar is converted to squirrel case induction as a load connected to grid and the positive or negative sequence current is determined by each equivalent circuit. As to the DFIG without a crowbar, negative sequence current is determined by its equivalent circuit and the positive sequence current is adjusted by the excitation system with its output related to the control of DFIG. The methods for calculating fault current contribution of DFIG under these two ride-through conditions are also presented. Then, the negative effect on protection that caused by different DFIG is studied. At the end, a case is set up to verify the accuracy of methods for calculating fault current contribution. The simulation result also shows the difference of DFIG fault current under different ride-through conditions.

[1]  Xu Cai,et al.  Dynamic Responses of DFIG Fault Currents Under Constant AC Exitation Condition , 2009, 2009 Asia-Pacific Power and Energy Engineering Conference.

[2]  Jiang Da-wei,et al.  DFIG-based wind farm equivalent model for power system short circuit current calculation , 2009, 2009 International Conference on Sustainable Power Generation and Supply.

[3]  M. S. Vicatos,et al.  Transient state analysis of a doubly-fed induction generator under three phase short circuit , 1991 .

[4]  J. Morren,et al.  Short-Circuit Current of Wind Turbines With Doubly Fed Induction Generator , 2007, IEEE Transactions on Energy Conversion.

[5]  Gang Wang,et al.  Equivalent Model for Calculating Short Circuit Current of Doubly Fed Wind Generator under Uninterrupted Excitation , 2011, 2011 Asia-Pacific Power and Energy Engineering Conference.

[6]  Zhe Zhang,et al.  The Research on the Characteristic of Fault Current of Doubly-Fed Induction Generator , 2009, 2009 Asia-Pacific Power and Energy Engineering Conference.

[7]  Xingjia Yao,et al.  Uninterrupted operation of doubly-fed induction generator based wind turbine during network , 2007, 2007 International Conference on Electrical Machines and Systems (ICEMS).

[8]  P. Sanchis,et al.  Dynamic Behavior of the Doubly Fed Induction Generator During Three-Phase Voltage Dips , 2007, IEEE Transactions on Energy Conversion.

[9]  Xiaofu Xiong,et al.  The impacts on short-circuit current and protection in distribution network caused by DFIG-based wind generation , 2010, 2010 International Conference on Power System Technology.

[10]  J. López,et al.  Wind Turbines Based on Doubly Fed Induction Generator Under Asymmetrical Voltage Dips , 2008, IEEE Transactions on Energy Conversion.

[11]  M.F. Conlon,et al.  Performance of a Variable Speed Double-Fed Induction Generator Wind Turbine During Network Voltage Unbalance Conditions , 2006, Proceedings of the 41st International Universities Power Engineering Conference.

[12]  D.D. Li.  Analysis and calculation of short circuit current of doubly fed induction generator , 2008, 2008 IEEE/PES Transmission and Distribution Conference and Exposition.