Method for operating a wind turbine
A method for operating a wind turbine that includes a generator device for outputting electric energy to a network, the generator device having a stator, and a controller device for controlling the generator device. To ensure sufficient protection of the wind turbine even during network fluctuations, a network voltage is determined using a network model at least as a function of a stator voltage measured with a first measuring apparatus and a network power measured with a second measuring apparatus, and the determined network voltage and a predeterminable maximum phase angle present between the stator voltage and network voltage are used to determine the maximum effective power of the wind turbine that can be output, and the output effective power is regulated as a function of the determined maximum effective power that can be output and a target effective power predetermined by the control device.
1. A method for operating a wind energy plant having a generator device for outputting electrical energy to a grid, wherein the generator device comprises a stator, and having a control device for controlling the generator device, wherein a stator voltage of the generator device is measured at least with one first measuring device, and a grid current output to the grid is measured at least with one second measuring device, wherein a grid voltage is determined using a grid model at least as a function of the stator voltage and the grid current, the maximum effective power of the wind energy plant that can be output is determined from the determined grid voltage and a pre-determinable maximum phase angle existing between stator voltage and grid voltage, and the output effective power is controlled as a function of the determined maximum effective power that can be output and a target effective power pre-determined by the control device.
2. The method according to claim 1 , wherein the determined maximum effective power that can be output is compared to the pre-determined target effective power and when the maximum effective power that can be output is exceeded by the target effective power the target effective power is restricted to the maximum effective power that can be output.
3. The method according to claim 1 , wherein the maximum effective power that can be output is determined continuously, periodically or once.
4. The method according to claim 1 , wherein the grid voltage is calculated from the stator voltage, the grid current and a grid impedance.
5. The method according to claim 4 , wherein the grid impedance is calculated from at least two stator voltages measured at different points in time and from at least two grid currents measured at different points in time.
6. The method according to claim 5 , wherein the grid impedance is determined continuously, periodically or once.
7. The method according to claim 1 , wherein the maximum phase angle (δ max ) between the stator voltage and the grid voltage is set to less than or equal to 85°.
8. The method according to claim 1 , wherein a double-fed asynchronous machine is used.
9. A computer program with commands, the execution of which causes a processor to carry out the method according to claim 1 .
10. A computer program product which contains a computer program with commands, the execution of which causes a processor to carry out the method according to claim 1 .
11. A control device of a generator device of a wind energy plant, wherein the control device comprises means for controlling the effective power output from the generator device to a grid according to a method according to claim 1 .
12. A wind energy plant comprising a generator device and a control device according to claim 11 .
13. The method according to claim 1 , wherein the maximum phase angle (δ max ) between the stator voltage and the grid voltage is set to less than or equal to 70°.