For the conventional crowbar-based low-voltage ride-through (LVRT) strategies for doubly-fed induction generator (DFIG)

not only is the flexibility of the driving converter not made full use of

but also today’s stringent grid-connection codes can hardly be well satisfied. Besides

some transient compensation based control strategies for asymmetrical grid fault are short of experimental verifications. Therefore

the electromagnetic transients of DFIG during grid faults are analyzed and discussed at length

based on which it is found that the high rotor terminal voltage during the process is mainly caused by the direct current (DC) and negative-sequence components included in the stator fluxes. To overcome the impact

an effective LVRT strategy is studied

in which some transient compensations based on the DC and negative-sequence components are provided to the rotor circuit timely and exactly. With the compensations

the magnitude of the transient rotor voltage is reduced to the lowest level for allowable rotor currents. As a result

the transient controllability of DFIG is strengthened

and the controllable range of voltage dip is expanded. Therefore

the performance of LVRT for DFIG is improved. The proposed analysis and design is validated by experiment on an 11 kW test-rig for wind turbines.