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A method of operating a wind turbine, wherein the wind turbine may include rotor windings of an induction generator, which includes stator coils coupled to a voltage grid, fed with rotor currents by a feed-in unit are driven by a rotor of the wind turbine; wherein the frequencies of the fed-in rotor

A method of operating a wind turbine, wherein the wind turbine may include rotor windings of an induction generator, which includes stator coils coupled to a voltage grid, fed with rotor currents by a feed-in unit are driven by a rotor of the wind turbine; wherein the frequencies of the fed-in rotor currents are controlled depending on the rotor rotation frequency and the feed-in unit is electrically decoupled from the rotor windings in the case predetermined variations of the grid voltage amplitude and the rotor current feed-in is resumed after the decoupling caused by the variation of the grid voltage amplitude, when the currents generated in the motor windings by the variation have declined to a predetermined value.

대표청구항 ▼

The invention claimed is: 1. A method of operating a wind turbine, comprising: driving a rotor of the wind turbine by feeding rotor currents by a feed-in unit to rotor windings of an induction generator, which comprises stator coils coupled to a voltage grid; controlling the frequencies of the fed-

The invention claimed is: 1. A method of operating a wind turbine, comprising: driving a rotor of the wind turbine by feeding rotor currents by a feed-in unit to rotor windings of an induction generator, which comprises stator coils coupled to a voltage grid; controlling the frequencies of the fed-in rotor currents depending on the rotor rotation frequency; electrically decoupling the feed-in unit from the rotor windings in the case of predetermined variations of the grid voltage amplitude by an emergency unit; releasing the fed-in rotor currents after electrically decoupling the feed-in unit using a release arrangement of the emergency unit; and when the rotor currents in the rotor windings by the variation have declined to a predetermined value, resuming the driving of the rotor of the wind turbine by feeding rotor currents by the feed-in unit to rotor windings of the induction generator after the decoupling caused by the variation of the grid voltage amplitude. 2. The method according to claim 1, wherein feeding rotor currents comprises feeding the rotor currents via a converter coupled to the grid voltage, wherein the converter is an intermediate DC voltage converter with a rotor-sided rotor current converter and a grid-sided grid converter. 3. The method according to claim 2, wherein during the decoupling the grid-sided grid converter remains coupled to the voltage grid and rotor-sided rotor current converter is blocked. 4. The method according to claims 1, 2, or 3,-wherein electrically decoupling comprises short-circuiting the rotor windings. 5. A wind turbine, comprising: a rotor with at least one rotor blade, the rotor being rotatably arranged with regard to a substantially horizontal rotor axis; an induction generator whose rotor windings are coupled to the rotor and whose stator coils can be coupled to a voltage grid; a feed-in unit for feeding currents into the rotor windings; a control unit for controlling the frequency of the fed-in currents depending on the rotor rotation frequency, and an emergency unit which can be operated to electrically decouple the feed-in unit from the rotor windings in case of variations of the grid voltage amplitude, wherein the emergency unit comprises a release arrangement for releasing the rotor current feed-in after decoupling, when the currents generated in the rotor windings by variation of the grid voltage amplitude triggering the decoupling are declined to a predetermined value. 6. The wind turbine according to claim 5, wherein the rotor is coupled to the rotor windings via a gear unit. 7. The wind turbine according to claim 5, wherein the feed-in unit comprises a converter coupled to the grid voltage. 8. The wind turbine according to claim 7, wherein the converter is an intermediate DC voltage converter with a rotor-sided rotor current converter and a grid-sided grid converter. 9. The wind turbine according to claim 5, wherein the emergency unit comprises a crow bar for short-circuiting the rotor windings. 10. The wind turbine according to claim 5, wherein the control unit is adapted for controlling the amplitude position and/or the phase position of the currents fed into the rotor windings. 11. The wind turbine of claim 6, wherein the feed-in unit comprises a converter coupled to the grid voltage. 12. The wind turbine of claim 11, wherein the converter is an intermediate DC voltage converter with a rotor-sided rotor current converter and a grid-sided grid converter. 13. The wind turbine of claim 6, wherein the emergency unit comprises a crow bar for short-circuiting the rotor windings. 14. The wind turbine of claim 7, wherein the emergency unit comprises a crow bar for short-circuiting the rotor windings. 15. The wind turbine of claim 8, wherein the emergency unit comprises a crow bar for short-circuiting the rotor windings. 16. The wind turbine of claim 6, wherein the control unit is adapted for controlling the amplitude position and/or the phase position of the currents fed into the rotor windings. 17. The wind turbine of claim 7, wherein the control unit is adapted for controlling the amplitude position and/or the phase position of the currents fed into the rotor windings. 18. The wind turbine of claim 8, wherein the control unit is adapted for controlling the amplitude position and/or the phase position of the currents fed into the rotor windings. 19. The wind turbine of claim 9, wherein the control unit is adapted for controlling the amplitude position and/or the phase position of the currents fed into the rotor windings.