Study On Control Strategy Of Doubly-fed Induction Generator Low Voltage Ride Through

With the rapidly increase of wind power generation capacity, its influence on grid is becoming more and more remarkable. Especially grid requires that grid connection wind turbine must be equipped with low voltage ride through (LVRT) capability for voltage dip that caused by faults in the power system. Because all turbines disconcetion induced power impulse to the grid.This paper encloses the dynamic behavior of DFIG under the condiction when faults in the power system and control strategy for low voltage ride through operation.This paper firstly analyses the operation principle of DFIG and the electromagnetism transient simulation model of grid connected of DFIG is established. The fact and cause of the fact that restrict DFIG low voltage ride through operation educed by analyzing the dynamic behavior of DFIG during voltage dips in the grid.For these reasons, the rotor side converters adopted the precise model of DFIG that the stator magenetizing current is considered for improving the control ability of the rotor side converter.Improved feed forward control strategy is adopted by grid side converter for decreasing maximum peak of DC bus voltage fluctuation.Adopting these modified schemes, the DFIG can be ride though operation under small scale voltage dip.The crowbar protection scheme is adapted to reslove the problem of large scale voltage dip.With this control strategy the DFIG is able to achieve ride through the more severe grid voltage dips.The fact that influences the crowbar protection effect is analysed.Simulation results prove that with these control strategy the LVRT ability of the DFIG can be effectively improved and satisfies the grid request.