Research On Enhancing Low Voltage Ride-through Ability Of Doubly-fed Induction Wind Turbine Generator

With the development of wind power generation system in recent years, large-scale wind turbine generators have been connected in the grid. During the period of a grid fault, the loss of these wind generators will influence the stability of the grid seriously. LVRT (low voltage ride-through) ability in grid fault condition is required. The study of enhancing LVRT ability of wind turbine generator has important significance to the utilization efficiency of wind energy and the stability of the grid.This thesis focuses on the doubly-fed induction wind turbine generator which is a kind of main type wind turbine generator, analyses the structure and the operation principle of DFIG(doubly-fed induction generator) model, a doubly-fed induction generator digital model is established in d-q synchronous coordinate system, transient electromagnetic relation is studied, the reason of over-current and over-voltage which was induced in rotor winding of DFIG is studied, the complete Matlab simulation model of DFIG has been established, the simulation result of operation performance of DFIG under three-phase short circuit shows that the LVRT ability must be enhanced to protect DFIG. Under the situation of three different short circuits, the simulation results of operation performance of DFIG verified crowbar circuit is effective. Further, analyzing the resistance in the circuit and the shut time of crowbar circuit how influence the LVRT ability through simulation, reasonable collocation is proposed based on the simulation results, this collocation can enhance the LVRT ability more effectively.