Method to individually optimize respective pitch angles of a plurality of blades in a wind turbine

Patent metadata

Field	Value
Publication number	US-9518560-B2
Application number	US-201313903180-A
Country	US
Kind code	B2
Filing date	May 28, 2013
Priority date	May 28, 2013
Publication date	Dec 13, 2016
Grant date	Dec 13, 2016

Abstract

A method to individually optimize respective pitch angles of blades in a wind turbine. The method allows supplying ( 102 ) a modulation signal to modulate a pitch angle of the individual blade being optimized. The method further allows filtering ( 104 ) output power of the turbine subject to the modulating frequency to extract a power signal in a frequency spectrum including the modulating frequency. The extracted power signal and a demodulation signal are mixed ( 106 ) to generate a signal including a product of the extracted power signal and the demodulation signal. The generated signal is filtered ( 108 ) to remove the modulating frequency and extract a gradient signal effective to search a pitch angle estimate conducive to optimize output power of the turbine. The gradient signal may be integrated ( 110 ) to cause the gradient signal to converge towards an optimal pitch angle for the individual blade being optimized.

First claim

The invention claimed is:

1. A method to individually optimize respective pitch angles of a plurality of blades in a wind turbine, the method comprising:
a) supplying a modulation signal having a predefined modulating frequency to modulate at the modulating frequency a pitch angle of only a respective one of the plurality of blades being presently optimized;
b) filtering output power of the wind turbine subject to the modulating frequency to extract a power signal in a frequency spectrum comprising at least the modulating frequency;
c) mixing the extracted power signal and a demodulation signal oscillating at the modulating frequency to generate a signal comprising a product of the extracted power signal and the demodulation signal;
d) filtering the generated signal to remove at least the modulating frequency and extract a gradient signal effective to search a pitch angle estimate conducive to optimize output power of the turbine; and
e) integrating the gradient signal to cause the gradient signal to converge towards a value indicative of an optimal pitch angle for the respective one of the plurality of blades being presently optimized.

2. The method of claim 1 , wherein the modulation signal comprises a periodic signal.

3. The method of claim 1 , wherein the modulation signal comprises a sinusoid.

4. The method of claim 1 , wherein the modulation signal comprises a random signal.

5. The method of claim 1 , further comprising: f) adding a present value of the integrated gradient signal to the modulation signal to modulate at the modulating frequency a present value of pitch angle for the respective one of the plurality of blades.

6. The method of claim 5 , further comprising iteratively performing steps b) through f) to reach or approximate a zero value for the gradient signal and thus establish the optimal pitch angle for the respective one of the plurality of blades.

7. The method of claim 6 , further comprising setting the respective one of the plurality of blades to the optimal pitch angle.

8. The method of claim 1 , further comprising adjusting a gain for the integrated gradient signal.

9. The method of claim 1 , wherein prior to the mixing step, estimating a difference in a phase angle of the extracted power signal relative to a phase angle of the demodulating signal.

10. The method of claim 9 , compensating the estimated phase angle difference to provide a substantially in-phase relationship between the extracted power signal and the demodulation signal.

11. The method of claim 5 , further comprising supplying the modulation signal to modulate a pitch angle of a further one of the plurality of blades of the wind turbine to be optimized next.

12. The method of claim 11 , further comprising iteratively performing steps b) through f) to establish an optimal pitch angle for the further one of the plurality of blades.

13. The method of claim 1 , wherein the supplying of the modulation signal comprises concurrently supplying a plurality of modulating signals at respective different modulating frequencies to simultaneously modulate at a respective different modulating frequency the pitch angle of each individual one of the plurality of blades, and concurrently performing at least one or more iterations to establish a respective optimal pitch angle for each one of the plurality of blades.

14. A method to individually optimize respective pitch angles of a plurality of blades in a wind turbine, the method comprising:
concurrently supplying a plurality of modulating signals each having a different modulating frequency to individually modulate at a respective different modulating frequency the respective pitch angle of each individual one of the plurality of blades; and
processing output power of the wind turbine to extract respective gradient signals responsive to the modulating signals to search respective pitch angle estimates conducive to optimize output power of the turbine.

15. The method of claim 14 , wherein the processing of output power of the wind turbine further comprises:
filtering output power of the wind turbine to extract respective power signals in a frequency spectrum comprising at least the different modulating frequencies;
mixing each of the extracted power signals with a corresponding demodulation signal oscillating at a respective one of the different modulating frequencies to generate respective signals each comprising a product of a respective one of the extracted power signals and the corresponding demodulation signal; and
filtering the respective generated signals to remove at least each different modulating frequency and extract the respective gradient signals.

16. The method of claim 15 , further comprising integrating the respective gradient signals to cause each gradient signal to converge towards respective values indicative of respective optimal pitch angles for each of the plurality of blades being concurrently optimized.

17. The method of claim 16 , further comprising adding a respective present value of each integrated gradient signal to the modulation signals to modulate at each different modulating frequency respective present values of pitch angles for the plurality of blades.

18. The method of claim 17 , further comprising performing at least a further iteration of the processing of output power of the wind turbine to reach or approximate a zero value for the respective gradient signals and thus establish the respective optimal pitch angles for each of the plurality of blades.

19. A method to individually optimize a respective pitch angle of blades of a wind turbine, the method comprising:
a) applying a modulation to a pitch angle of only one blade of a wind turbine;
b) integrating a change in a power signal of the wind turbine responsive to the modulation;
c) adjusting the pitch angle of the one blade in response to the integrated power signal;
d) repeating steps a) through c) until the integrated power signal achieves a prede-termined value indicating that a desired optimal pitch angle has been achieved for the one blade; and
e) repeating steps a) through d) for a further one of the blades of the wind turbine.

20. At least one non-transitory processor-readable storage medium comprising processor-readable code stored therein, which when executed by at least one processor, the computer-readable code causes the processor to perform the method of claim 19 .

Assignees

• Creaby Justin
• Siemens Ag

Inventors

• Creaby Justin

Classifications

• Y02E10/723

  Cross-Sectional Technologies · mapped topic

• F03D7/0224 Primary

  Adjusting blade pitch · CPC title

• Y02E10/72

  Wind turbines with rotation axis in wind direction · CPC title