Research on control of DFIG with active crowbar under symmetry voltage fault condition

With the development of wind power generation system, LVRT (low voltage ride through) ability in grid fault condition is required for wind generator, so it's necessary to research on the control method of DFIG (doubly fed induction generator) under symmetry voltage fault condition. During the occurrence of a grid fault, because of electromagnetic relationship in DFIG, over current way induced in stator and rotor winding. In order to protect the converter, crowbar was used to short DFIG rotor. When over current was induced in rotor, the rotor side converter was bypassed by active crowbar circuit. When rotor current decreased to a certain degree, the crowbar circuit was opened. At the same time the rotor side converter was activated, active and reactive power was fed to the grid. The theory analysis was verified by the simulation result and the LVRT operation of DFIG was achieved through the active crowbar.