Analysis on Low Voltage Ride-Through Techniques for Wind Turbines Using Doubly-Fed Induction Generator

2012 ◽  
Author(s):  
Shunjie Han ◽  
Meng Han ◽  
Yue Han
Keyword(s):  
Wind Turbines ◽  
Low Voltage ◽  
Induction Generator ◽  
Doubly Fed Induction Generator ◽  
Low Voltage Ride Through ◽  
Doubly Fed

Improvement of the Low-Voltage Ride-through Capability of Doubly Fed Induction Generator Wind Turbines

2012 ◽  
Vol 36 (5) ◽  
pp. 535-551 ◽  
Author(s):  
Yu Ling ◽  
Zhenlan Dou ◽  
Qiang Gao ◽  
Xu Cai
Keyword(s):  
Wind Turbines ◽  
Low Voltage ◽  
Induction Generator ◽  
Voltage Sags ◽  
Doubly Fed Induction Generator ◽  
Low Voltage Ride Through ◽  
Logic Control ◽  
Comparison Results ◽  
Long Time ◽  
Doubly Fed

So far, active crowbars are a preferred technique for doubly fed induction generator (DFIG) wind turbines, which is used to protect the power converter against over-current and undesirably high dc link voltage during voltage dip. However, its main drawbacks are that (1) the DFIG absorbs reactive power from the grid during grid voltage dips, (2) the crowbar activation increases the acceleration of the rotor and so, deteriorates the dynamic stability of DFIG, and (3) the control is not flexible for long-time voltage sags. In the paper, three different initiating logic control methods of crowbar protection are compared, and how low-voltage ride-through (LVRT) characteristics of DFIG wind turbines with active crowbar are affected by different switching logic control modes of the crowbar are investigated. According to the comparison results, an improved crowbar switching control strategy is proposed to reduce its operation time and improve the LVRT capability of DFIG wind turbines. In addition, an emergency pitch blade angle control scheme to reduce the acceleration of the rotor and prevent the over-speeding of rotor is presented in detail, and as a result, the LVRT capability of DFIG wind turbines is enhanced even during long-time voltage sags. Finally, the presented control strategies are validated in simulation tool Matalab/Simulink for a 1.5MW generator.

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