Demagnetization control for doubly-fed induction generator under balanced grid fault

Doubly-fed induction generator is one of the most popular machines for variable speed wind turbine. However, it is very sensitive to grid fault. This paper analyzed the low voltage ride-through performance of a doubly-fed induction generator based wind turbine under balanced grid fault. A demagnetization control, immune to system parameter variation, is proposed to promote DC stator flux damping. The investigation shows that the proposed control strategy can notably shorten the transient process under balanced grid fault. To meet the low voltage ride-through requirement, coordination control of active, reactive and demagnetizing current is also given in this paper. In order to verify the proposed control method, laboratory experiments are carried out and the results demonstrated the analysis.