Method of detecting damage of wind turbine blade, and wind turbine

Patent metadata

Field	Value
Publication number	US-10697440-B2
Application number	US-201715671776-A
Country	US
Kind code	B2
Filing date	Aug 8, 2017
Priority date	Feb 13, 2017
Publication date	Jun 30, 2020
Grant date	Jun 30, 2020

Abstract

A method of detecting a damage of a wind turbine blade of a wind turbine rotor includes: a light input step of inputting light into a fiber-optic sensor mounted to the wind turbine blade; a light detection step of detecting reflection light from the grating portion; an obtaining step of obtaining a wavelength fluctuation index representing a fluctuation amount of a wavelength of the reflection light detected in the light detection step; and a detection step. The detection step includes detecting the presence or the absence of the damage of the wind turbine blade based on the wavelength fluctuation index taking account of a correlation between the wavelength fluctuation index of the wind turbine blade and a load index related to a load applied to the wind turbine blade, or a correlation between the wavelength fluctuation index and a temperature index related to a temperature of the wind turbine blade.

First claim

The invention claimed is:

1. A method of detecting a damage of a wind turbine blade of a wind turbine rotor including at least one wind turbine blade, the method comprising:
a light input step of inputting light into a fiber-optic sensor mounted to each of the wind turbine blade and having a grating portion at which a refractive index changes periodically in a longitudinal direction;
a light detection step of detecting reflection light from the grating portion;
an obtaining step of obtaining a wavelength fluctuation index which represents a fluctuation amount of a wavelength of the reflection light detected in the light detection step from a temporal change of the wavelength; and
a detection step of detecting presence or absence of a damage of the wind turbine blade on the basis of the wavelength fluctuation index calculated in the obtaining step,
wherein the detection step comprises detecting the presence or the absence of the damage of the wind turbine blade on the basis of the wavelength fluctuation index taking account of at least one of a correlation between the wavelength fluctuation index of the wind turbine blade and a load index related to a load applied to the wind turbine blade, or a correlation between the wavelength fluctuation index of the wind turbine blade and a temperature index related to a temperature of the wind turbine blade, and
wherein the detection step comprises detecting the presence or the absence of the damage of the wind turbine blade on the basis of a result of comparison between an evaluation value obtained from the wavelength fluctuation index of the wind turbine blade and a corrected threshold that is corrected on the basis of the correlation.

2. The method of detecting a damage of a wind turbine blade according to claim 1 ,
wherein the detection step comprises detecting the presence or the absence of the damage of the wind turbine blade on the basis of a result of comparison between an evaluation value obtained from the wavelength fluctuation index of the wind turbine blade and a threshold, and
wherein the evaluation value to be compared to the threshold is a corrected evaluation value corrected on the basis of the correlation.

3. The method of detecting a damage of a wind turbine blade according to claim 1 ,
wherein the wind turbine rotor comprises a plurality of wind turbine blades, and
wherein the detection step comprises:
calculating an average of the wavelength fluctuation index of the plurality of wind turbine blades as the load index;
obtaining the corrected threshold or the corrected evaluation value on the basis of correlation between the wavelength fluctuation index of one wind turbine blade to be detected among the plurality of wind turbine blades and the average of the wavelength fluctuation index of the plurality of wind turbine blades; and
detecting the damage of the wind turbine blade by using the corrected threshold or the corrected evaluation value.

4. The method of detecting a damage of a wind turbine blade according to claim 1 ,
wherein the detection step comprises:
specifying a temperature range in which an absolute value of a change rate of the wavelength fluctuation index relative to the temperature index becomes larger; and
detecting the damage of the wind turbine blade by using the corrected threshold or the corrected evaluation value obtained on the basis of the correlation between the wavelength fluctuation index of the wind turbine blade and the temperature index when a temperature of the wind turbine blade is in the temperature range.

5. The method of detecting a damage of a wind turbine blade according to claim 1 ,
wherein the obtaining step comprises calculating a difference between a maximum of the wavelength and a minimum of the wavelength in the temporal change as the wavelength fluctuation index.

6. The method of detecting a damage of a wind turbine blade according to claim 5 ,
wherein the obtaining step comprises calculating a difference between the maximum and the minimum which appear alternately and repeatedly corresponding to a rotation period of the wind turbine rotor as the wavelength fluctuation index.

7. The method of detecting a damage of a wind turbine blade according to claim 1 , further comprising:
a time-average calculation step of calculating an average of the wavelength fluctuation index calculated in the obtaining step for a period not shorter than a rotation period of the wind turbine rotor,
wherein the detection step comprises detecting the damage of the wind turbine blade on the basis of the average calculated in the time-average calculation step.

8. The method of detecting a damage of a wind turbine blade according to claim 1 ,
wherein the wind turbine rotor comprises a plurality of wind turbine blades,
wherein the method further comprises a difference calculation step of calculating a difference between the wavelength fluctuation index of one wind turbine blade to be detected from among the plurality of wind turbine blades and a reference value reflecting the wavelength fluctuation index of at least one wind turbine blade for comparison from among remaining wind turbine blades as the evaluation value, and
wherein the detection step comprises detecting the damage of the wind turbine blade to be detected on the basis of a temporal change of the difference calculated in the difference calculation step.

9. The method of detecting a damage of a wind turbine blade according to claim 8 ,
wherein the wind turbine rotor comprises three or more wind turbine blades,
wherein the difference calculation step is repeated for each of the wind turbine blades being the wind turbine blade to be detected to calculate the difference for each of the wind turbine blades, and
wherein the detection step comprises specifying the wind turbine blade having the damage on the basis of the difference of each of the wind turbine blades.

10. A method of detecting a damage of a wind turbine blade of a wind turbine rotor including at least one wind turbine blade, the method comprising:
a light input step of inputting light into a fiber-optic sensor mounted to each of the wind turbine blade and having a grating portion at which a refractive index changes periodically in a longitudinal direction;
a light detection step of detecting reflection light from the grating portion;
an obtaining step of obtaining a wavelength fluctuation index which represents a fluctuation amount of a wavelength of the reflection light detected in the light detection step from a temporal change of the wavelength; and
a detection step of detecting presence or absence of a damage of the wind turbine blade on the basis of the wavelength fluctuation index calculated in the obtaining step,
wherein the detection step comprises detecting the presence or the absence of the damage of the wind turbine blade on the basis of the wavelength fluctuation index taking account of at least one of a correlation between the wavelength fluctuation index of the wind turbine blade and a load index related to a load applied to the wind turbine blade, or a correlation between the wavelength fluctuation index of the wind turbine blade and a temperature index related to a temperature of the wind turbine blade,
wherein the obtaining step comprises calculating a difference between a maximum of the wavelength and a minimum of the wavelength in the temporal change as the wavelength fluctuation index, and
wherein, provided that T is a rotation period of the wind turbine rotor, the obtaining step comprises not determining a second extreme value next to a first extreme value which is the maximum or the minimum, until a period t (where 0.1 T≤t≤0.5 T) elapses after a point of time whe

Assignees

• Mitsubishi Heavy Ind Ltd

Inventors

• Ikawa Yoshikatsu
• Takita Katsuhiko
• Kuroiwa Takao
• Baba Mitsuya
• Ide Kazunari
• Koyanagi Takuya

Classifications

• F05B2270/803

  Sampling thereof · CPC title

• F05B2270/326

  Rotor angle · CPC title

• G01L1/246

  using integrated gratings, e.g. Bragg gratings · CPC title

• G01M5/0033

  by determining damage, crack or wear · CPC title

• F03D17/00 Primary

  Monitoring or testing of wind motors, e.g. diagnostics (testing during commissioning of wind motors F03D13/30) · CPC title