Fan blade multi-parameter monitoring device based on fiber bragg grating

Abstract

A fan blade multi-parameter monitoring device based on fiber bragg gratings comprises a laser transmitter, a demodulator and an optical fiber sensor. The optical fiber sensor comprises a sheath and a core layer, the sheath is connected with a fan blade, the core layer is provided with a plurality of gratings with short grating region lengths, the core layer is sequentially connected with the optical fiber circulator and the laser transmitter, the laser transmitter is connected with the interferometer and the controller, and the optical fiber circulator is further connected with the demodulator and the controller. Incident light signals enter the optical fiber sensor through the optical fiber circulator, the incident light signals generate reflected light signals in the grating, and then the reflected light signals enter the demodulator and the controller to be processed so as to obtain the structure and state information of the blade. The optical fiber sensor is good in electromagnetic interference resistance, so that the monitoring effect is good; the optical grating with the short gate region length reduces the loss of reflected light signals, and the monitoring effect is improved. Therefore, the fan blade monitoring device is good in electromagnetic interference resistance and good in fan blade monitoring effect.

Description

Technical Field

[0001] The utility model relates to a fan blade detection device, belongs to the field of fan blade detection, and particularly relates to a fan blade multi-parameter monitoring device based on optical fiber grating. Background Art

[0002] Wind power generation is a renewable and clean energy source with little environmental pollution, a high degree of automation, and easy remote control. It can meet the electricity needs of sparsely populated areas where power grids are difficult to reach. Therefore, wind power generation has important economic and social benefits.

[0003] Nowadays, with the expansion of my country's wind energy market and the rapid development of wind turbine manufacturing industry, wind power generation equipment is developing in the direction of large-scale, intelligent, high-efficiency and low-cost. Wind turbines are one of the core equipment of wind power generation, and blades are important components of wind turbines. In order to meet the needs of development, the size of blades has become larger and larger. Large blades are also one of the most vulnerable components in wind turbines. Problems such as structural damage, icing, pitch angle deviation and cracks may occur, which will not only bring different degrees of safety hazards, but also cause the working performance of blades to decline after the blade structure is damaged, resulting in economic losses such as wind turbine shutdown. Therefore, blade health monitoring and early detection and positioning of faults are of great significance to the safe and stable operation of wind turbines. At present, traditional electrical sensors are used for blade monitoring, but electrical sensors have poor anti-electromagnetic interference, which leads to poor monitoring effect of blades.

[0004] The information disclosed in this background technology section is only intended to increase the understanding of the overall background of the application, and should not be regarded as acknowledging or suggesting in any form that the information constitutes the prior art already known to ordinary technicians in this field. Summary of the invention

[0005] The purpose of the utility model is to overcome the defects and problems of poor monitoring effect on fan blades in the prior art, and to provide a fan blade multi-parameter monitoring device based on fiber grating with better monitoring effect on fan blades.

[0006] To achieve the above objectives, the technical solution of the utility model is:

[0007] A multi-parameter monitoring device for fan blades based on fiber grating, the device comprising a laser transmitter, a demodulator and a fiber optic sensor;

[0008] The optical fiber sensor comprises a sheath and a core layer inside the sheath, the outer surface of the sheath is connected to the outer surface of the fan blade, a Bragg grating array is arranged on the core layer, and a plurality of gratings with short grating lengths are evenly distributed on the Bragg grating array;

[0009] One end of the core layer is connected to the connection outlet end of the optical fiber circulator, the analysis outlet end of the optical fiber circulator is connected to one end of the demodulator, and the other end of the demodulator is connected to one end of the controller;

[0010] The laser inlet end of the optical fiber circulator is connected to the first laser outlet end of the laser transmitter; the second laser outlet end of the laser transmitter is connected to one end of the auxiliary demodulation device, and the other end of the auxiliary demodulation device is connected to one end of the controller.

[0011] The inner side of the outer surface of the sheath is connected to the root, the blade tip and the web of the fan blade.

[0012] The demodulator includes an optical switch, a static demodulator and a dynamic demodulator; the optical switch includes a switch input end, a static output end and a dynamic output end, the switch input end is connected to the analysis output end, the static output end is connected to one end of the static demodulator, and the dynamic output end is connected to one end of the dynamic demodulator.

[0013] The dynamic demodulator includes a two-by-two coupler, a time-delay optical fiber, an unbalanced Mark-Zehnder interferometer and a three-by-three coupler;

[0014] One end of the two-by-two coupler is connected to the moving outlet end, the other end of the two-by-two coupler is connected to the delay optical fiber and one end of the unbalanced Mark-Zehnder interferometer, the other end of the delay optical fiber is connected to one end of the three-by-three coupler, and the other end of the unbalanced Mark-Zehnder interferometer is connected to one end of the three-by-three coupler.

[0015] One end of the three-by-three coupler is connected to the first photodetector, and the other end of the first photodetector is connected to one end of the controller; one end of the three-by-three coupler is connected to the second photodetector, and the other end of the second photodetector is connected to one end of the controller; one end of the three-by-three coupler is connected to the third photodetector, and the other end of the third photodetector is connected to one end of the controller.

[0016] The static demodulator comprises a static photoelectric detector, one end of which is connected to the static outlet end, and the other end of which is connected to one end of the controller.

[0017] One end of the controller is connected to a rotation speed sensor, and the rotation speed sensor is located at the root of the fan blade.

[0018] The laser transmitter comprises a laser and a one-by-two coupler, one end of the laser is connected to the inlet end of the one-by-two coupler, and the outlet end of the one-by-two coupler is respectively connected to the first laser outlet end and the second laser outlet end.

[0019] The second laser outlet end is connected to one end of the erbium-doped fiber amplifier, and the other end of the erbium-doped fiber amplifier is connected to the laser inlet end.

[0020] The auxiliary demodulation device includes an interferometer and a contrast photodetector, one end of the interferometer is connected to the second laser outlet end, the other end of the interferometer is connected to one end of the contrast photodetector, and the other end of the contrast photodetector is connected to one end of the controller.

[0021] Compared with the prior art, the beneficial effects of the utility model are:

[0022] 1. The utility model is a multi-parameter monitoring device for wind turbine blades based on fiber gratings, comprising a laser transmitter, a fiber optic sensor and a demodulator; the fiber optic sensor comprises a sheath and a core layer, a Bragg grating array is arranged on the core layer, a plurality of gratings with short grating lengths are evenly distributed on the Bragg grating array, the core layer is connected to one end of a fiber optic circulator, another end of the fiber optic circulator is connected to a demodulator and a controller in sequence, another end of the fiber optic circulator is connected to a laser transmitter, and the laser transmitter is connected to an auxiliary demodulation device and a controller in sequence. When used, when the wind turbine blades are working, an incident light signal is first generated by the laser transmitter, the incident light signal then passes through the fiber optic circulator and enters the fiber optic sensor, and then the incident light signal generates a reflected light signal in the grating, the reflected light signal then enters the fiber optic circulator along the fiber optic sensor, and then the reflected light signal enters the demodulator for demodulation to obtain data information, and the data information enters the controller for processing to obtain monitoring results. The advantages of the utility model also include:

[0023] First point: a grating with a short grating length is used to sense and monitor the blades. When the blade structure is damaged, including damage due to high temperature or strain, the central wavelength of the reflected light signal will be offset, so a wavelength offset will be generated. When the working state of the blade is abnormal, that is, when the blade is in an abnormal vibration state, the phase delay variation of the reflected light signal of the Bragg grating will change. The wavelength offset and phase delay variation are then converted into data information, and then the data information is processed by the controller to obtain specific information about the damage of the blade structure or abnormal working state.

[0024] Second point: Compared with traditional electrical sensors, fiber optic sensors have the advantage of better resistance to electromagnetic interference; when the blade structure is damaged or the working state is abnormal, the physical structure of the grating will change, so the wavelength offset and phase delay change of the reflected light signal will change. When used in conjunction with a demodulator and a controller, the damaged part of the blade can be accurately located, so the monitoring effect of the fiber optic sensor is better; and when using fiber optic sensors, no additional sensors and complex power supply and communication lines are required, less wiring, and less interference to the measured physical quantity;

[0025] Third point: The length of the grating with short grating length is about two to four millimeters, so the maximum reflectivity of the grating is lower, and the spectrum of the reflected light signal is wider, which helps to reduce the loss and interference of the reflected light signal, thereby improving the quality and efficiency of communication, and then improving the monitoring accuracy;

[0026] Fourth point: The demodulator and the controller can obtain the temperature and strain information of the blade through the wavelength offset, thereby obtaining the information of the blade structure damage; the demodulator and the controller can obtain the vibration information of the blade through the phase delay variation. When the blade vibrates abnormally, it means that the working state of the blade is abnormal, so the working state of the blade can be monitored; therefore, the utility model can monitor the structural damage and working state of the blade by monitoring the wavelength offset and phase delay variation of the reflected light signal, that is, the blade can be monitored with multiple parameters, so the monitoring of the blade is more comprehensive;

[0027] Fifth point: Because the demodulator and controller can obtain the structure and working status information of the blade, there is no need to use two sets of equipment to monitor the structural damage and working status of the blade respectively, thus reducing the monitoring cost;

[0028] Therefore, the utility model has good anti-electromagnetic interference performance and better monitoring effect on fan blades.

[0029] 2. In the utility model, a multi-parameter monitoring device for fan blades based on fiber grating, the fiber circulator is connected to the demodulator of the optical switch, the demodulator also includes a dynamic demodulator and a static demodulator, the dynamic demodulator includes a two-by-two coupler, a delayed optical fiber, an unbalanced Mark-Zehnder interferometer, a three-by-three coupler and three photodetectors, the static demodulator is a static photodetector, when used, the fiber circulator receives the reflected light signal, and then allows the reflected light signal to enter the optical switch, the optical switch allows the reflected light signal to enter the static demodulator or the dynamic demodulator, the static demodulator and the dynamic demodulator convert the reflected light signal into data information; the optical switch is used to switch the static demodulator and the dynamic demodulator, so as to realize the alternating monitoring of the damaged blade structure and the working state, thereby improving the monitoring efficiency. Therefore, the monitoring efficiency of the utility model is relatively high.

[0030] 3. In the utility model of a multi-parameter monitoring device for fan blades based on fiber grating, the controller is also connected to a speed sensor, which is located at the root of the fan blade. When used, the speed sensor can obtain the output power of the fan blade. When it is detected that the wind speed and the output power are not linearly related within a certain unit time, it means that the working state of the fan blade is abnormal, and the fiber optic sensor is used for monitoring; therefore, the fiber optic sensor does not need to be turned on all the time, which can save power resources. Therefore, the utility model is green and environmentally friendly.

[0031] 4. In the utility model, a multi-parameter monitoring device for wind turbine blades based on fiber grating, the laser transmitter includes a laser, a one-by-two coupler, the fiber circulator is also connected to an erbium-doped fiber amplifier, and the auxiliary demodulation device includes an interferometer and a contrast photodetector. When used, the laser emits an incident light signal, which is then divided into two incident light signals through a one-by-two coupler, and the light intensity ratio of the two incident light signals is about 95:5. The incident light signal with a stronger light intensity is amplified by the erbium-doped fiber amplifier and then enters the fiber circulator to obtain a reflected light signal. The incident light signal with a weaker light intensity enters the controller through the interferometer and the contrast photodetector as a wavelength auxiliary demodulation signal to compare the data information of the demodulator; the erbium-doped fiber amplifier can amplify the incident light signal, increase the intensity of the incident light signal, so that the incident light signal can be transmitted over a longer distance, expanding the monitoring range of the utility model. Therefore, the monitoring range of the utility model is relatively wide. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a structural schematic diagram of the utility model.

[0033] Figure 2 yes Figure 1 Schematic diagram of the structure of the optical fiber sensor.

[0034] Figure 3 yes Figure 2 Schematic diagram of the structure of the Bragg grating array.

[0035] Figure 4 yes Figure 1 Schematic diagram of the demodulator structure.

[0036] Figure 5 yes Figure 4 Schematic diagram of the structure of the static demodulator.

[0037] Figure 6 yes Figure 4 Schematic diagram of the structure of the dynamic demodulator.

[0038] Figure 7 yes Figure 1 Schematic diagram of the structure of the laser transmitter.

[0039] Figure 8 It is an application schematic diagram of the utility model.

[0040] Fig. 9 yes Figure 8 Schematic diagram of the structure of the middle blade.

[0041] Fig.10 It is a flow chart of the utility model.

[0042] Fig.11 yes Figure 2Spectrum of the incident light signal.

[0043] Fig.12 yes Figure 2 Spectrum of the transmitted light signal.

[0044] Fig.13 yes Figure 2 Spectrum of the reflected light signal.

[0045] In the figure: laser transmitter 1, first laser outlet 11, second laser outlet 12, auxiliary demodulation device 13, contrast photodetector 131, interferometer 132, laser 14, one-by-two coupler 15, erbium-doped fiber amplifier 16, fiber sensor 2, core layer 21, grating 211, Bragg grating array 212, short grating length 213, sheath 22, cladding 24, demodulator 3, optical switch 31, static outlet 311, dynamic outlet 312, switch inlet 313, Static demodulator 32, static photodetector 321, dynamic demodulator 33, two-by-two coupler 331, delay optical fiber 332, unbalanced Mark-Zehnder interferometer 333, three-by-three coupler 334, first photodetector 335, second photodetector 336, third photodetector 337, optical fiber circulator 4, connection outlet end 41, analysis outlet end 42, laser inlet end 43, fan blade 5, root 51, blade tip 52, web 53, controller 6, speed sensor 7. DETAILED DESCRIPTION

[0046] The present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0047] See also Figure 1 — Fig.13 , a wind turbine blade multi-parameter monitoring device based on fiber grating, the device comprises a laser transmitter 1, a demodulator 3 and a fiber optic sensor 2;

[0048] The optical fiber sensor 2 includes a sheath 22 and a core layer 21 therein, wherein the outer surface of the sheath 22 is connected to the outer surface of the fan blade 5, and a Bragg grating array 212 is provided on the core layer 21, and a plurality of gratings 211 with short grating lengths 213 are evenly distributed on the Bragg grating array 212;

[0049] One end of the core layer 21 is connected to a connection outlet 41 on the optical fiber circulator 4, an analysis outlet 42 on the optical fiber circulator 4 is connected to one end of the demodulator 3, and the other end of the demodulator 3 is connected to one end of the controller 6;

[0050] The laser inlet end 43 on the optical fiber circulator 4 is connected to the first laser outlet end 11 on the laser transmitter 1; the second laser outlet end 12 on the laser transmitter 1 is connected to one end of the auxiliary demodulation device 13, and the other end of the auxiliary demodulation device 13 is connected to one end of the controller 6.

[0051] The inner side of the outer surface of the sheath 22 is connected to the root 51 , the blade tip 52 , and the web 53 of the fan blade 5 .

[0052] The demodulator 3 includes an optical switch 31, a static demodulator 32 and a dynamic demodulator 33; the optical switch 31 includes a switch input end 313, a static output end 311 and a dynamic output end 312, the switch input end 313 is connected to the analysis output end 42, the static output end 311 is connected to one end of the static demodulator 32, and the dynamic output end 312 is connected to one end of the dynamic demodulator 33.

[0053] The dynamic demodulator 33 includes a two-by-two coupler 331 , a delay optical fiber 332 , an unbalanced Mark-Zehnder interferometer 333 and a three-by-three coupler 334 ;

[0054] One end of the two-by-two coupler 331 is connected to the moving outlet end 312, the other end of the two-by-two coupler 331 is connected to the delay optical fiber 332 and one end of the unbalanced Mark-Zehnder interferometer 333, the other end of the delay optical fiber 332 is connected to one end of the three-by-three coupler 334, and the other end of the unbalanced Mark-Zehnder interferometer 333 is connected to one end of the three-by-three coupler 334.

[0055] One end of the three-by-three coupler 334 is connected to the first photodetector 335, and the other end of the first photodetector 335 is connected to one end of the controller 6; one end of the three-by-three coupler 334 is connected to the second photodetector 336, and the other end of the second photodetector 336 is connected to one end of the controller 6; one end of the three-by-three coupler 334 is connected to the third photodetector 337, and the other end of the third photodetector 337 is connected to one end of the controller 6.

[0056] The static demodulator 32 includes a static photodetector 321 , one end of which is connected to the static outlet port 311 , and the other end of which is connected to one end of the controller 6 .

[0057] One end of the controller 6 is connected to a rotation speed sensor 7 , and the rotation speed sensor 7 is located at the root of the fan blade 5 .

[0058] The laser transmitter 1 includes a laser 14 and a one-by-two coupler 15, one end of the laser 14 is connected to the inlet end of the one-by-two coupler 15, and the outlet end of the one-by-two coupler 15 is connected to the first laser outlet end 11 and the second laser outlet end 12 respectively.

[0059] The second laser outlet port 12 is connected to one end of an erbium-doped fiber amplifier 16 , and the other end of the erbium-doped fiber amplifier 16 is connected to the laser inlet port 43 .

[0060] The auxiliary demodulation device 13 includes an interferometer 132 and a contrast photodetector 131, one end of the interferometer 132 is connected to the second laser outlet end 12, the other end of the interferometer 132 is connected to one end of the contrast photodetector 131, and the other end of the contrast photodetector 131 is connected to one end of the controller 6.

[0061] The supplementary description of this utility model is as follows:

[0062] The function of the fiber circulator 4 of the utility model is: the transmitted light signal moves to the Bragg grating array 212 through the fiber circulator 4, and the reflected light signal moves to the demodulator 3 through the fiber circulator 4; see Fig.11 — Fig.13 , Fig.11 is the spectrum of the incident light signal, Fig.12 is the spectrum of the transmitted light signal, Fig.13 is the spectrum of the reflected light signal.

[0063] Embodiment 1:

[0064] See also Figure 1 — Fig.13 , a multi-parameter monitoring device for wind turbine blades based on fiber gratings, the device comprising a laser transmitter 1, a demodulator 3 and a fiber sensor 2; the fiber sensor 2 comprises a sheath 22 and a core layer 21 inside thereof, the outer surface of the sheath 22 is connected to the outer surface of a wind turbine blade 5, a Bragg grating array 212 is arranged on the core layer 21, and a plurality of gratings 211 with short grating lengths 213 are evenly distributed on the Bragg grating array 212; one end of the core layer 21 is connected to a connection outlet end 41 on a fiber circulator 4, an analysis outlet end 42 on the fiber circulator 4 is connected to one end of the demodulator 3, and the other end of the demodulator 3 is connected to one end of a controller 6; a laser inlet end 43 on the fiber circulator 4 is connected to a first laser outlet end 11 on the laser transmitter 1; a second laser outlet end 12 on the laser transmitter 1 is connected to one end of an auxiliary demodulation device 13, and the other end of the auxiliary demodulation device 13 is connected to one end of a controller 6. The inner side of the outer surface of the sheath 22 is connected to the root 51 , the blade tip 52 , and the web 53 of the fan blade 5 .

[0065] When in use, the sheath 22 is first wound along the root 51 of the fan blade 5 to the blade tip 52, and then the sheath 22 is wound from the blade tip 52 of the fan blade 5 along the web 53 to the root 51 of the fan blade 5, and then the sheath 22 is connected and fixed to the outer surface of the fan blade 5; then the fan blade 5 starts to work, that is, the fan blade 5 enters a rotating state; then the laser transmitter 1 simultaneously emits a first beam of incident light signal and a second beam of incident light signal, and the first beam of incident light signal then moves from the first laser outlet end 11 to the laser inlet end 43, and then the first beam of incident light signal is sent from the laser transmitter 1 to the laser outlet end 43. The connection outlet 41 moves toward the core layer 21, the first incident light signal enters the core layer 21 again, and then the first incident light signal generates a reflected light signal on the grating 211 in the Bragg grating array 212, and the reflected light signal moves along the core layer 21 toward the connection outlet 334, and then the reflected light signal enters the demodulator 3 and the controller 6 from the analysis outlet 42 for processing; at the same time, the second incident light signal moves from the second laser outlet 12 to the auxiliary demodulation device 13, and the second incident light signal is converted by the auxiliary demodulation device 13 and then enters the controller 6; the controller 6 summarizes the reflected light signal and the second incident light signal, and the controller 6 processes the reflected light signal and the second incident light signal to obtain the strain information, temperature information and vibration information of the fan blade 5, and then the controller 6 obtains the structural damage information of the fan blade 5 from the strain information and the temperature information, and then the controller 6 obtains the working state information of the fan blade 5 from the vibration information; when the physical quantities such as the temperature, strain and vibration of the fan blade 5 change, the physical structure of the grating 211 of the corresponding part changes, thereby causing the central wavelength of the reflected light signal to change, and the controller 6 can obtain the part of the fan blade 5 with structural damage or abnormal working state according to the change of the central wavelength; in the monitoring process, the optical fiber sensor 2 is used as the main sensor, and the Bragg grating array 212 is used as the sensing medium, wherein the length of the grating 211 is the short grating length 213, so the maximum reflectivity of the grating 211 is low, the spectrum of the reflected light signal is wide, the loss and interference of the reflected light signal are less, so the communication quality of the reflected light signal is high, and the monitoring accuracy of the optical fiber sensor 2 is high.

[0066] Embodiment 2:

[0067] The basic content is the same as that of Example 1, except that:

[0068] See also Figure 1 — Fig.13The demodulator 3 includes an optical switch 31, a static demodulator 32 and a dynamic demodulator 33; the optical switch 31 includes a switch input port 313, a static output port 311 and a dynamic output port 312, the switch input port 313 is connected to the analysis output port 42, the static output port 311 is connected to one end of the static demodulator 32, and the dynamic output port 312 is connected to one end of the dynamic demodulator 33. The dynamic demodulator 33 includes a two-by-two coupler 331, a delay optical fiber 332, an unbalanced Mark-Zehnder interferometer 333 and a three-by-three coupler 334; one end of the two-by-two coupler 331 is connected to the dynamic output end 312, the other end of the two-by-two coupler 331 is connected to the delay optical fiber 332 and one end of the unbalanced Mark-Zehnder interferometer 333, the other end of the delay optical fiber 332 is connected to one end of the three-by-three coupler 334, and the other end of the unbalanced Mark-Zehnder interferometer 333 is connected to one end of the three-by-three coupler 334. One end of the three-by-three coupler 334 is connected to the first photodetector 335, and the other end of the first photodetector 335 is connected to one end of the controller 6; one end of the three-by-three coupler 334 is connected to the second photodetector 336, and the other end of the second photodetector 336 is connected to one end of the controller 6; one end of the three-by-three coupler 334 is connected to the third photodetector 337, and the other end of the third photodetector 337 is connected to one end of the controller 6. The static demodulator 32 includes a static photodetector 321, one end of the static photodetector 321 is connected to the static outlet end 311, and the other end of the static photodetector 321 is connected to one end of the controller 6.

[0069] When used, the reflected light signal first reaches the optical switch 31, and the optical switch 31 allows the reflected light signal to enter the static outlet port 311 or the dynamic outlet port 312; after the reflected light signal enters the dynamic outlet port 312, the reflected light signal moves to the two-by-two coupler 331, and then the reflected light signal moves to the delay optical fiber 332 and the unbalanced Mark-Zehnder interferometer 333. At this time, the delay optical fiber 332, the unbalanced Mark-Zehnder interferometer 333 and the Bragg grating array 212 form a quasi-equal-arm interference structure, so that when the reflected light signals of two adjacent Bragg grating arrays 212 reach the delay optical fiber 332 and the unbalanced Mark-Zehnder interferometer 333, they overlap in the time domain and interfere with each other, thereby obtaining an interference signal, and then the interference signal moves to the three-by-three coupler 334, and the interference signal is processed by the first photodetector 335, the second photodetector 336, and the third photodetector 337 into data information containing the phase delay variation, and then the data information containing the phase delay variation enters the controller 6 and is processed into the fan blade 5 vibration information; the greater the phase delay variation, the greater the vibration generated by the fan blade 5; when the reflected light signal enters the static outlet end 311, the reflected light signal moves to the static demodulator 32, and the reflected light signal enters the static photoelectric detector 321 to be processed into data information containing wavelength offset, and then the data information containing wavelength offset enters the controller 6 to be processed into temperature and strain information of the fan blade 5; when the temperature of the fan blade 5 increases, the structure of the fan blade 5 will be damaged. The greater the temperature variation or the greater the strain, the greater the wavelength offset of the reflected light signal; the optical switch 31 can make the reflected light signal enter the static demodulator 32 or the dynamic demodulator 33, even if the reflected light signal in one optical fiber sensor 2 can alternately enter the static demodulator 32 and the dynamic demodulator 33 to be processed, so as to obtain data information containing wavelength offset or data information containing phase delay variation, so as to achieve the effect of using one optical fiber sensor 2 to obtain temperature, strain and vibration information, so the monitoring of the utility model is more comprehensive.

[0070] Embodiment 3:

[0071] The basic content is the same as that of Example 1, except that:

[0072] See also Figure 1 — Fig. 9 One end of the controller 6 is connected to a rotation speed sensor 7 , and the rotation speed sensor 7 is located at the root of the fan blade 5 .

[0073] When in use, the speed sensor 7 is fixed to the root of the fan blade 5. After the fan blade 5 enters the working state, the speed sensor 7 can obtain the output power of the fan blade 5. Generally, when the wind speed increases, the output power of the fan blade 5 also increases. When the speed sensor 7 detects that the wind speed and the output power of the fan blade 5 are not linearly related within a certain unit time, it means that the structure of the fan blade 5 is damaged or the working state is abnormal. The speed sensor 7 then notifies the controller 6 to start and then monitors the fan blade 5.

[0074] Embodiment 4:

[0075] The basic content is the same as that of Example 1, except that:

[0076] See also Figure 1 — Figure 7 The laser transmitter 1 includes a laser 14 and a one-by-two coupler 15, one end of the laser 14 is connected to the inlet end of the one-by-two coupler 15, and the outlet end of the one-by-two coupler 15 is respectively connected to the first laser outlet end 11 and the second laser outlet end 12. The second laser outlet end 12 is connected to one end of an erbium-doped fiber amplifier 16, and the other end of the erbium-doped fiber amplifier 16 is connected to the laser inlet end 43. The auxiliary demodulation device 13 includes an interferometer 132 and a contrast photodetector 131, one end of the interferometer 132 is connected to the second laser outlet end 12, the other end of the interferometer 132 is connected to one end of the contrast photodetector 131, and the other end of the contrast photodetector 131 is connected to one end of the controller 6. Preferably, the interferometer 132 is a Fabry-Perot interferometer.

[0077] When used, the laser 14 first emits an incident light signal, and the incident light signal then passes through the one-by-two coupler 15. At this time, the incident light signal is divided into a first beam incident light signal and a second beam incident light signal. The light intensity ratio of the first beam incident light signal to the second beam incident light signal is 95:5. Then the first beam incident light signal passes through the first laser outlet 11, and then enters the erbium-doped fiber amplifier 16 to be amplified to further enhance the light intensity. Then the first beam incident light signal passes through the laser inlet 43 and the connection outlet 41 and then enters the core layer 21 for monitoring; the second beam incident light signal passes through the second laser outlet 12, and then enters the interferometer 132. Then the second incident light signal enters the comparison photodetector 131 and is processed into data information containing the comparison amount. The data information containing the comparison amount then enters the controller 6 as auxiliary demodulation information of the demodulator 3 containing the wavelength offset and the phase delay change.

[0078] The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiment. Any equivalent modifications or changes made by ordinary technicians in this field based on the contents disclosed in the present invention should be included in the protection scope recorded in the claims.

Claims

1. A multi-parameter monitoring device for fan blades based on fiber grating, characterized in that: The device comprises a laser transmitter (1), a demodulator (3) and an optical fiber sensor (2); The optical fiber sensor (2) comprises a sheath (22) and a core layer (21) therein; the outer surface of the sheath (22) is connected to the outer surface of the fan blade (5); a Bragg grating array (212) is provided on the core layer (21); and a plurality of gratings (211) with short grating lengths (213) are evenly distributed on the Bragg grating array (212); One end of the core layer (21) is connected to a connection outlet end (41) on the optical fiber circulator (4), an analysis outlet end (42) on the optical fiber circulator (4) is connected to one end of a demodulator (3), and the other end of the demodulator (3) is connected to one end of a controller (6); The laser inlet end (43) on the optical fiber circulator (4) is connected to the first laser outlet end (11) on the laser transmitter (1); the second laser outlet end (12) on the laser transmitter (1) is connected to one end of an auxiliary demodulation device (13); and the other end of the auxiliary demodulation device (13) is connected to one end of a controller (6).

2. The wind turbine blade multi-parameter monitoring device based on fiber grating according to claim 1 is characterized in that: The inner side of the outer surface of the jacket (22) is connected to the root (51), the blade tip (52), and the web (53) of the fan blade (5).

3. A wind turbine blade multi-parameter monitoring device based on fiber grating according to claim 1 or 2, characterized in that: The demodulator (3) comprises an optical switch (31), a static demodulator (32) and a dynamic demodulator (33); the optical switch (31) comprises a switch inlet end (313), a static outlet end (311) and a dynamic outlet end (312); the switch inlet end (313) is connected to an analysis outlet end (42); the static outlet end (311) is connected to one end of the static demodulator (32); and the dynamic outlet end (312) is connected to one end of the dynamic demodulator (33).

4. The wind turbine blade multi-parameter monitoring device based on fiber grating according to claim 3 is characterized in that: The dynamic demodulator (33) comprises a two-by-two coupler (331), a time-delay optical fiber (332), an unbalanced Mark-Zehnder interferometer (333) and a three-by-three coupler (334); One end of the two-by-two coupler (331) is connected to the moving exit end (312), the other end of the two-by-two coupler (331) is connected to the delay optical fiber (332) and one end of an unbalanced Mark-Zehnder interferometer (333), the other end of the delay optical fiber (332) is connected to one end of a three-by-three coupler (334), and the other end of the unbalanced Mark-Zehnder interferometer (333) is connected to one end of the three-by-three coupler (334).

5. The wind turbine blade multi-parameter monitoring device based on fiber grating according to claim 4 is characterized in that: One end of the three-by-three coupler (334) is connected to a first photodetector (335), and the other end of the first photodetector (335) is connected to one end of a controller (6); one end of the three-by-three coupler (334) is connected to a second photodetector (336), and the other end of the second photodetector (336) is connected to one end of the controller (6); one end of the three-by-three coupler (334) is connected to a third photodetector (337), and the other end of the third photodetector (337) is connected to one end of the controller (6).

6. The wind turbine blade multi-parameter monitoring device based on fiber grating according to claim 5, characterized in that: The static demodulator (32) comprises a static photoelectric detector (321), one end of the static photoelectric detector (321) is connected to the static outlet end (311), and the other end of the static photoelectric detector (321) is connected to one end of the controller (6).

7. A wind turbine blade multi-parameter monitoring device based on fiber grating according to claim 1 or 2, characterized in that: One end of the controller (6) is connected to a rotation speed sensor (7), and the rotation speed sensor (7) is located at the root of the fan blade (5).

8. A wind turbine blade multi-parameter monitoring device based on fiber grating according to claim 1 or 2, characterized in that: The laser transmitter (1) comprises a laser (14) and a one-by-two coupler (15), one end of the laser (14) is connected to an inlet end of the one-by-two coupler (15), and an outlet end of the one-by-two coupler (15) is respectively connected to a first laser outlet end (11) and a second laser outlet end (12).

9. The wind turbine blade multi-parameter monitoring device based on fiber grating according to claim 8, characterized in that: The second laser outlet end (12) is connected to one end of an erbium-doped fiber amplifier (16), and the other end of the erbium-doped fiber amplifier (16) is connected to a laser inlet end (43).

10. The wind turbine blade multi-parameter monitoring device based on fiber grating according to claim 9, characterized in that: The auxiliary demodulation device (13) comprises an interferometer (132) and a contrast photoelectric detector (131); one end of the interferometer (132) is connected to the second laser outlet end (12); the other end of the interferometer (132) is connected to one end of the contrast photoelectric detector (131); and the other end of the contrast photoelectric detector (131) is connected to one end of the controller (6).

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