Modeling and Control of Wind-Turbine Used DFIG under Network Fault Conditions

摘要

Doubly-Fed Induction Generator (DFIG) has been widely used in Variable-Speed Constant- Frequency (VSCF) wind energy generation system. Vector control is already applied to the DFIG control, which makes the DFIG gain good performance in the wind energy capturing operation. But in the two traditional vector control schemes, the stator magnetizing current is considered invariant in order to simplify the rotor current inner-loop controller. The two schemes are capable of performing very well when the grid is in normal condition. However, when the grid disturbance, such as grid voltage dip or swell fault, occurs, the control performance will be getting worse, the rotor over current will occur, which seriously reduce the ride-through ability of the DFIG wind energy generation system. Based on the accurate model of the DFIG, the deficiency of the traditional vector control is deeply investigated. The improved control schemes of the two typical traditional vector control schemes used in DFIG is proposed, and the simulation study of the proposed and traditional control schemes is carried out. The validity of the proposed modified schemes to control the rotor current and to improve the ride-through ability of the DFIG wind energy generation system is proved by the comparison study.