US 7,321,221 B2
Method for operating a wind power plant and method for operating it
Andreas Bücker, Hasbergen (Germany); Wilhelm Janssen, Saterland (Germany); and Henning Lütze, Bad Bentheim (Germany)
Assigned to General Electric Company, Schenectady, N.Y. (US)
Appl. No. 10/521,614
PCT Filed Jul. 17, 2003, PCT No. PCT/EP03/07776
§ 371(c)(1), (2), (4) Date Feb. 10, 2006,
PCT Pub. No. WO2004/008627, PCT Pub. Date Jan. 22, 2004.
Claims priority of application No. 102 32 423 (DE), filed on Jul. 17, 2002.
Prior Publication US 2006/0163881 A1, Jul. 27, 2006
Int. Cl. H20P 9/00 (2006.01)
U.S. Cl. 322—44  [322/55; 322/43; 322/54; 322/25] 19 Claims
OG exemplary drawing
 
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.