A fan blade icing monitoring system and method based on laser intensity measurement

Abstract

The present invention discloses a wind turbine blade icing monitoring system and method based on laser intensity measurement, which belongs to the technical field of wind power generation. It includes a circular laser beam generating system, a first light intensity measuring instrument, an optical fiber transmission system, a second light intensity measuring instrument and a data processing and analysis system; the circular laser beam generating system is arranged inside the blade root, and the first light intensity measuring instrument is connected to the circular laser beam generating system; the second light intensity measuring instrument is arranged on the blade surface; the input end of the optical fiber transmission system is connected to the circular laser beam generating system, and the output end is directly opposite to the second light intensity measuring instrument, and the area between the output end and the second light intensity measuring instrument is an icing monitoring area; the first light intensity measuring instrument and the second light intensity measuring instrument are respectively connected to the data processing and analysis system. The present invention realizes the effective monitoring of the formation and development of icing on the blade surface in the target area, and has the advantages of high sensitivity and high accuracy in icing detection.

Description

Technical Field

[0001] The present invention belongs to the technical field of wind power generation, and in particular relates to a system and method for monitoring icing of wind turbine blades based on laser intensity measurement. Background Art

[0002] Wind farms in low wind speed areas and some high wind speed areas in the south generally have serious freezing problems in winter and spring. The general characteristic of wind turbines being covered with ice is that the temperature is above -10℃. In the winter in the south, when the temperature drops to 0℃, ice will appear on wind turbines and wind turbine blades. Blade icing changes the aerodynamic shape, weight distribution and frequency of the blades, breaks the load balance of the blades, and will cause problems such as vibration of the blades and wind rotors, which will have a direct impact on the operation, economy and safety of wind turbines.

[0003] When ice appears on the blades of a wind turbine, it is necessary to use methods such as hot air deicing and electric heating deicing to remove the ice on the blade surface to ensure the normal operation of the wind turbine under low temperature weather conditions. The intelligent deicing system for wind turbine blades needs to be based on the accurate prediction and monitoring of blade ice. For example, if thin ice within 3mm on the blade surface can be detected, the deicing system will start running at a lower power, which can effectively remove ice and inhibit the continuous growth of the ice layer. It also reduces the energy consumption of the deicing system, which has a significant effect on the intelligent operation and economic improvement of the entire deicing system. Therefore, how to accurately predict and monitor blade ice is a problem that needs to be solved urgently. Summary of the invention

[0004] In order to solve the above problems, the purpose of the present invention is to provide a wind turbine blade icing monitoring system and method based on laser intensity measurement, which realizes effective monitoring of the formation and development of ice on the blade surface in the target area, and has the advantages of high sensitivity and accuracy in icing detection.

[0005] The present invention is achieved through the following technical solutions:

[0006] The invention discloses a fan blade icing monitoring system based on laser intensity measurement, comprising a circular laser beam generating system, a first light intensity measuring instrument, an optical fiber transmission system, a second light intensity measuring instrument and a data processing and analysis system;

[0007] The circular laser beam generating system is arranged inside the blade root, and the first light intensity measuring instrument is connected to the circular laser beam generating system; the second light intensity measuring instrument is arranged on the blade surface; the input end of the optical fiber transmission system is connected to the circular laser beam generating system, and the output end is facing the second light intensity measuring instrument, and the area between the output end and the second light intensity measuring instrument is the ice monitoring area; the first light intensity measuring instrument and the second light intensity measuring instrument are respectively connected to the data processing and analysis system.

[0008] Preferably, the circular laser beam generating system comprises a laser emitter and an aperture filter, the laser emitter faces the optical fiber transmission system, and the aperture filter is arranged on the circular laser beam propagation path between the laser emitter and the optical fiber transmission system.

[0009] Further preferably, the aperture diameter of the aperture filter is 2-3 mm, and the aperture of the aperture is adjustable, and the diameter of the measuring surface of the second light intensity measuring instrument is greater than the diameter of the circular laser beam.

[0010] Further preferably, a spectroscope is provided between the aperture filter and the optical fiber transmission system, and the first light intensity measuring instrument is provided on the reflected light path of the spectroscope.

[0011] Further preferably, the included angle between the beam splitter and the laser emitted by the laser emitter is 45°, and the intensity of the reflected light of the beam splitter is 4% to 5% of the intensity of the laser emitted by the laser emitter.

[0012] Preferably, the optical fiber transmission system includes a laser input terminal, an optical fiber and a laser output terminal. The laser input terminal is arranged in the blade root and faces the circular laser beam generating system. The laser output terminal is arranged on the blade surface and faces the second light intensity measuring instrument. The two ends of the optical fiber are respectively connected to the laser input terminal and the laser output terminal.

[0013] Further preferably, a protective cover is provided at the front end of the laser output terminal.

[0014] Preferably, the wavelength of the laser emitted by the circular laser beam generating system is 10 -2 ~10 -1 μm.

[0015] Preferably, the data processing and analysis system includes an oscilloscope, a signal processor and a computer, the first light intensity measuring instrument and the second light intensity measuring instrument are respectively connected to the oscilloscope, the oscilloscope is connected to the signal processor, and the signal processor is connected to the computer.

[0016] The method for monitoring fan blade icing using the fan blade icing monitoring system based on laser intensity measurement disclosed in the present invention comprises:

[0017] The circular laser beam generating system emits a circular laser beam, the light intensity of which is measured by the first light intensity measuring instrument and then transmitted to the second light intensity measuring instrument via the optical fiber transmission system. When an ice layer is formed in the ice monitoring area between the output end of the optical fiber transmission system and the second light intensity measuring instrument, the data processing and analysis system realizes ice monitoring of the wind turbine blades based on the changes in the light intensity values ​​measured by the first light intensity measuring instrument and the second light intensity measuring instrument and combined with the time development characteristics.

[0018] Compared with the prior art, the present invention has the following beneficial technical effects:

[0019] The present invention discloses a wind turbine blade icing monitoring system based on laser intensity measurement. By measuring the intensity of the laser before and after passing through the icing detection area, effective monitoring of the blade icing detection area can be achieved. A circular laser beam generating system is constructed inside the blade root, which effectively utilizes the larger space inside the blade root and is less affected (or can be ignored) by the operation of the wind turbine blade yaw. At the same time, the icing state can be monitored during the normal operation of the wind turbine, and is not affected by the blade waving and swinging. By integrating the physical properties of the laser passing through the icing layer, the sensitivity of the light intensity measuring instrument to capture the laser intensity, and the recording, processing and analysis of the light intensity signal by the data processing and analysis system, the present invention can capture relatively small icing formation, study the time development law of the thickness of the icing layer, and provide a high-precision and accurate initial signal for the formulation of the wind turbine deicing control strategy and the start or stop of the deicing system, which is conducive to the efficient deicing of the wind turbine and ensures the healthy, safe and reliable operation of the wind turbine.

[0020] Furthermore, the circular laser beam generating system adopts a laser emitter and an aperture filter, and the aperture filter can make the cross section of the beam emitted by the laser emitter a circle with a set diameter.

[0021] Furthermore, the aperture of the aperture filter is adjustable to meet monitoring requirements in different situations. The diameter of the measuring surface of the second light intensity measuring instrument is greater than the diameter of the circular laser beam, ensuring that the second light intensity measuring instrument can capture the circular laser beam.

[0022] Furthermore, since the intensity of the laser will decay to a certain extent during the propagation process, the spectroscope detects the intensity of 4% to 5% of the reflected light of the laser beam, which can eliminate the interference of the laser intensity attenuation on the light intensity measurement and analysis.

[0023] Furthermore, the optical fiber transmission system is capable of long-distance lossless transmission via optical fiber.

[0024] Furthermore, a protective cover is provided at the front end of the laser output terminal, which can protect the laser output terminal from being affected by freezing and monitoring.

[0025] Furthermore, the wavelength of the laser emitted by the circular laser beam generating system is selected to be 10 -2 ~10 -1 μm, corresponding to the absorption coefficient of laser in pure ice being 10 4 ~10 6 cm -1 The higher level increases the ice's absorption of laser light and improves the accuracy of data analysis and ice recognition.

[0026] The method disclosed in the present invention for monitoring fan blade icing using the above-mentioned fan blade icing monitoring system based on laser intensity measurement has a high degree of automation, realizes effective monitoring of the formation and development of ice covering the blade surface in the target area, and has the advantages of high sensitivity and high accuracy in icing detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the overall structure of the system of the present invention;

[0028] Figure 2 for Figure 1 A partial enlarged view of;

[0029] Figure 3 It is a top-down diagram of the circular laser beam behavior when the ice monitoring area is full of ice;

[0030] Figure 4 It is a side view schematic diagram of the behavior of a circular laser beam when the ice monitoring area is full of ice;

[0031] Figure 5 This is a top view of the case where the laser is perpendicular to the incident surface of the ice layer and there is no gap between the ice layer and the photodiode;

[0032] Figure 6 This is a front view of the case where the laser is perpendicular to the incident surface of the ice layer and there is no gap between the ice layer and the photodiode;

[0033] Figure 7 This is a top view of the case where the laser is not perpendicular to the incident surface of the ice layer and there is no gap between the ice layer and the photodiode;

[0034] Figure 8 This is a front view of the case where the laser is not perpendicular to the incident surface of the ice layer and there is no gap between the ice layer and the photodiode;

[0035] Fig. 9 This is a top view of the case where the laser is perpendicular to the incident surface of the ice layer and there is a gap between the ice layer and the photodiode;

[0036] Fig.10 This is a front view of the case where the laser is perpendicular to the incident surface of the ice layer and there is a gap between the ice layer and the photodiode;

[0037] Fig.11 Schematic diagram of intensity distribution of the ratio of the light intensity signal intensity collected by the first light intensity measuring instrument to the light intensity signal intensity collected by the second light intensity measuring instrument at different stages of ice coverage in the embodiment.

[0038] In the figure: 1 is a laser transmitter; 2 is an aperture filter; 3 is a spectroscope; 4 is a first light intensity measuring instrument; 5 is a laser input terminal; 6 is an optical fiber; 7 is a laser output terminal; 8 is a protective cover; 9 is a second light intensity measuring instrument; 10 is a circular laser beam; 11 is a blade layer; 12 is a signal processor; 13 is a computer; 14 is a blade; 15 is a blade root; 16 is an ice layer; 17 is an oscilloscope; 18 is a parallel surface laser. DETAILED DESCRIPTION

[0039] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments, the contents of which are intended to explain the present invention rather than to limit it:

[0040] like Figure 1 The wind turbine blade icing monitoring system based on laser intensity measurement of the present invention arranges a circular laser beam generating system in a relatively large area inside the blade root 15 of a large wind turbine blade. The laser emitter 1 emits a laser beam of a specific wavelength and a stable intensity at a set frequency (e.g., 0.1 to 1 times / min) as a light source for monitoring ice on the surface of the blade 14. Combined with the experimental test data of the absorption coefficient of pure ice for lasers in different wavelength ranges, the laser wavelength can be selected to be between 10 -2 ~10 -1 μm, corresponding to the absorption coefficient of laser in pure ice being 10 4 ~10 6 cm -1 , which is at a relatively high level. The cross section of the laser beam output by the laser emitter 1 is not absolutely circular. In order to eliminate the influence of the beam cross section shape, an aperture filter 2 is arranged after the laser emitter 1. The structure of the aperture filter 2 is similar to the aperture of a camera, and the diameter of the light-transmitting circular hole in the center can be adjusted, so that the beam cross section of the laser after passing through the aperture filter 2 is a circle of a set diameter. In this embodiment, the aperture diameter is set to 2 to 3 mm.

[0041] Considering that the present invention measures the intensity of the circular laser beam 10 after passing through the ice layer 16 and compares the incident laser intensity to judge and monitor the ice state, in order to eliminate the influence of the output laser intensity attenuation caused by the laser emitter 1 itself on the data analysis, a spectroscope 3 is arranged after the aperture filter 2, and the spectroscope 3 is arranged at 45° with the circular laser beam 10, so that the circular laser beam 10 reflects part of the laser due to mirror reflection (4% to 5%, for a certain spectroscope 3 and arrangement angle, the reflection ratio is considered to remain unchanged), and the intensity of this part of the laser is measured by a first light intensity measuring instrument 4 (which can be a photodiode type) arranged vertically therewith and output to an oscilloscope 17, and the light intensity is displayed as a pulse signal on the oscilloscope 17, and the amplitude of the pulse is proportional to the reflected laser intensity. In this embodiment, the oscilloscope 17, the signal processor 12 and the computer 13 can be placed at the ground height in the tower to avoid increasing the load on the wind turbine when the system is running. On the oscilloscope 17 , the light intensity pulse signal is determined and transmitted to the downstream signal processor 12 . After being collected and processed by the signal processor 12 , the intensity signal is stored in the computer 13 .

[0042] The unreflected circular laser beam 10 all passes through the beam splitter 3. Since the blades 14 of wind turbines are generally long (on the order of 10 to 100 meters), the optical fiber 6 is used to guide the circular laser beam 10 to the ice detection area as a monitoring light source. The optical fiber 6 uses the total reflection phenomenon of light in materials with a large refractive index such as quartz to propagate long distances without loss. The two ends of the optical fiber 6 are respectively provided with a laser input terminal 5 and a laser output terminal 7, and their lengths depend on the distance between the ice detection area and the blade root 15. The height of the laser input terminal 5 is adjusted so that the circular laser beam 10 after the beam splitter 3 all enters the optical fiber 6 and propagates losslessly to the ice detection area. Most of the length of the optical fiber 6 is fixed to the inner surface of the wind turbine blade 14. Only a small hole with a diameter of no more than 5 mm is opened on the surface of the blade 14 in front of the ice detection area, and the optical fiber 6 is extended and the laser output terminal 7 is close to the outer surface of the blade 14.

[0043] The position of the optical fiber 6 in the laser output terminal 7 is adjusted to be biased toward the lower half, and a thin protective cover 8, such as a quartz glass cover plate, is installed at the front end of the laser output terminal 7, so that the lower edge of the circular laser beam 10 emitted from the protective cover 8 is tangent to the surface of the blade 14, that is, the upper surface of the blade layer 11.

[0044] At the other end of the ice detection area, a second light intensity meter 9 is arranged perpendicular to the surface of the blade 14, and the diameter of the light absorption surface of the second light intensity meter 9 is larger than the diameter of the circular laser beam 10 by 0.6 mm. The ice detection area can be long or short, but it should be ensured that there is no major change in the surface shape of the blade 14 within the detection area, that is, the lower edge of the circular laser beam 10 in this area is tangent to the surface of the blade 14, and in the absence of ice formation, all the laser light of the circular laser beam 10 is projected onto the light absorption surface of the second light intensity meter 9, ensuring that the laser light is completely absorbed and measured. Since the size of the optical fiber 6 section, laser output terminal 7, protective cover 8 and second light intensity meter 9 exposed on the surface of the blade 14 is small, the influence on the aerodynamic characteristics and load of the blade 14 can be ignored.

[0045] like Figure 2 The second light intensity measuring instrument 9 is connected to the oscilloscope 17 by a wire passing through the blade layer 11, and the laser intensity pulse signal measured by the second light intensity measuring instrument 9 is transmitted to the oscilloscope 17. The pulse signal is highly similar to the pulse signal emitted by the first light intensity measuring instrument 4 in terms of pulse width and other parameters, and the difference lies in the amplitude of the signal, that is, the difference in laser intensity. Similarly, the light intensity signal emitted by the second light intensity measuring instrument 9 is processed by the oscilloscope 17 and transmitted to the downstream signal processor 12, and is collected and processed by the signal processor 12 and stored in the computer 13.

[0046] If the intensity of the circular laser beam 10 emitted by the laser transmitter 1 and formed after passing through the aperture filter 2 is I 0 , the reflection ratio of the beam splitter 3 is 5%, then the light intensity signal intensity I output by the first light intensity measuring instrument 4 is 1 have:

[0047] I 1 =5%×a 1 ×I 0

[0048] When there is no ice on the surface of the blade 14, the light intensity signal intensity I output by the second light intensity measuring instrument 9 is 2 have:

[0049] I 2 =95%×a 2 ×I 0

[0050] Among them, a 1 and a 2 are the photoelectric conversion coefficients of the first light intensity measuring instrument 4 and the second light intensity measuring instrument 9, respectively. That is, when the laser emitter 1 emits laser light at a certain frequency (such as once / 20s), when no ice is formed, the I recorded by the computer 13 is 1 with I 2 There is a fixed proportional relationship R between 0This ratio is only related to the system. If the time development curve of R0 is recorded, the curve is a horizontal straight line.

[0051]

[0052] In fact, when ice appears in the ice monitoring area, due to the uncertainty of the ice formation area and the irregularity of the shape, it is actually impossible to fully describe the behavior of the circular laser beam 10 passing through ice layers of different positions and shapes, but in general, it can be referred to Figure 3 and Figure 4 situation.

[0053] If the space between the protective cover 8 and the second light intensity measuring instrument 9 is completely filled with ice, that is, the size of the ice exceeds the irradiation range of the circular laser beam 10 ( Figure 3 and Figure 4 ). In this case, as the laser propagates in the ice, the energy is gradually absorbed by the ice layer. Based on the basic law of absorption (Lambert-Beer Law), the laser intensity before and after the ice layer is as follows:

[0054] I out =I in exp(-αd)

[0055] Among them, I in and I out are respectively the laser intensity before and after the ice layer, that is, the laser intensity after the protective cover 8 and before the second light intensity measuring instrument 9. d and α are respectively the length and absorption coefficient of the ice layer along the laser propagation direction. In this embodiment, for the selected laser frequency and system design, d and α remain unchanged. For this case,

[0056]

[0057] Due to the absorption of laser light by ice, That is, the ratio value obtained by analytical calculation remains unchanged (which can be obtained by combining with system calculation) and is smaller than the ratio in the ice-free situation.

[0058] In fact, in the ice monitoring area of ​​the blade 14, since ice formation always gradually forms from an ice-free state, the I recorded by the computer 13 is recorded, processed and calculated. 1 with I 2 The ratio R 0 , draw R 0 The time development curve of ice cover can be used to effectively monitor the ice cover status.

[0059] The circular laser beam 10 can be regarded as a collection of several parallel laser beams 18 with width. In order to conveniently describe the propagation behavior of laser beams under different ice-covering conditions, Figures 5 to 10The figure shows several typical behaviors of the circular laser beam 10 being cut into several parallel planes 18 with widths along the laser propagation direction and perpendicular to the surface of the blade 14 under different ice covering conditions:

[0060] 1) If Figure 5 and 6 , the ice layer 16 is formed in front of the second light intensity measuring instrument 9 (without a gap in the middle), and the laser is perpendicular to the parallel plane laser 18 on the incident surface of the ice layer. The laser is not refracted in the ice layer 16, and the absorption of the laser by the ice layer 16 will cause the corresponding laser intensity to be weakened, while the remaining part of the circular laser beam 10 that does not penetrate the ice layer is directly captured by the second light intensity measuring instrument 9. The I recorded by the computer 13 1 with I 2 The ratio R 0 Between and between.

[0061] 2) If Figure 7 and 8 , an ice layer 16 is formed in front of the second light intensity measuring instrument 9 (without a gap in the middle), and the laser is not perpendicular to the parallel surface laser 18 on the incident surface of the ice.

[0062] 3) If Fig. 9 and 10 There is an air gap between the ice layer 16 and the second light intensity measuring instrument 9. The laser incident surface and the laser emission surface of the ice layer 16 are irregular (in the natural environment, it is difficult to form a similar Figure 5 and Figure 6 The regular ice surface in each of the two light intensity measuring devices is parallel to the second light intensity measuring device 9).

[0063] For the above cases 2) and 3), the laser will be reflected on the ice surface, refracted and reflected (or totally reflected) inside the ice layer 16 at the incident surface and inside the ice layer 16. On the one hand, the various optical behaviors of the laser passing through the ice layer 16 cause the laser position irradiated to the second light intensity measuring instrument 9 to deviate to the left or right from the laser position without ice blocking the upper part, and due to the reflection on the ice surface and the absorption of the ice layer, the intensity of this part of the laser intensity is reduced (or the intensity is zero due to the total reflection of the laser).

[0064] Figures 5 to 10The situation in which only one ice layer appears in the ice detection area is described. In the actual operation of the wind turbine, ice may appear at the same time, that is, there is more than one ice layer in the ice detection area. After the parallel laser 18 passes through the first ice layer, it is possible that the laser passes through the ice layer again and captures a more complex light spot and laser intensity on the second light intensity meter 9. However, in general, from the intensity pulse signal output by the second light intensity meter 9, after multiple ice layers and other complex situations, a considerable part of the circular laser beam 10 may not be irradiated to the second light intensity meter 9 (the diameter of the area where it captures the light intensity is only 0.6 mm larger than the diameter of the circular laser beam 10). In this case, the light intensity signal intensity I output by the second light intensity meter 9 is 2 The smaller.

[0065] In general, the present invention can fully predict and accurately measure the laser beam intensity in the two situations of no ice formation and full ice formation in the ice monitoring area, and calculate the corresponding ratio R 0 , presenting the following characteristics (see Fig.11 ):

[0066] 1) When there is no ice cover, and remain unchanged;

[0067] 2) When ice begins to form, R 0 The calculated value is less than Record R 0 The time development curve of R 0 The decrease in value may also present various characteristics;

[0068] 3) If there is no effective de-icing measure, the ice will continue to grow and eventually fill the entire ice-covered area. 0 The value will return to and remain unchanged.

[0069] It should be noted that the above is only a part of the implementation of the present invention, and equivalent changes made to the system described in the present invention are all included in the protection scope of the present invention. Those skilled in the art of the present invention can replace the specific examples described in a similar manner, as long as they do not deviate from the structure of the present invention or exceed the scope defined by the claims, they all belong to the protection scope of the present invention.

Claims

1. A fan blade icing monitoring system based on laser intensity measurement, characterized in that: It comprises a circular laser beam generating system, a first light intensity measuring instrument (4), an optical fiber transmission system, a second light intensity measuring instrument (9) and a data processing and analysis system; A circular laser beam generating system is arranged inside the blade root (15), and a first light intensity measuring instrument (4) is connected to the circular laser beam generating system; a second light intensity measuring instrument (9) is arranged on the surface of the blade (14); an input end of the optical fiber transmission system is connected to the circular laser beam generating system, and an output end faces the second light intensity measuring instrument (9), and an ice covering monitoring area is located between the output end and the second light intensity measuring instrument (9); the first light intensity measuring instrument (4) and the second light intensity measuring instrument (9) are respectively connected to a data processing and analysis system; The circular laser beam generating system comprises a laser emitter (1) and an aperture filter (2), the laser emitter (1) is directly opposite to the optical fiber transmission system, and the aperture filter (2) is arranged on a propagation path of the circular laser beam (10) between the laser emitter (1) and the optical fiber transmission system; The aperture diameter of the aperture filter (2) is 2-3 mm, and the aperture of the aperture is adjustable; the diameter of the measuring surface of the second light intensity measuring instrument (9) is greater than the diameter of the circular laser beam (10); A beam splitter (3) is provided between the aperture filter (2) and the optical fiber transmission system, and a first light intensity measuring instrument (4) is provided on the reflected light path of the beam splitter (3).

2. The wind turbine blade icing monitoring system based on laser intensity measurement according to claim 1, characterized in that: The included angle between the beam splitter (3) and the laser emitted by the laser emitter (1) is 45°, and the intensity of the reflected light of the beam splitter (3) is 4% to 5% of the intensity of the laser emitted by the laser emitter (1).

3. The wind turbine blade icing monitoring system based on laser intensity measurement according to claim 1, characterized in that: The optical fiber transmission system comprises a laser input terminal (5), an optical fiber (6) and a laser output terminal (7). The laser input terminal (5) is arranged in a blade root (15) and faces the circular laser beam generating system. The laser output terminal (7) is arranged on a surface of a blade (14) and faces a second light intensity measuring instrument (9). Two ends of the optical fiber (6) are respectively connected to the laser input terminal (5) and the laser output terminal (7).

4. The wind turbine blade icing monitoring system based on laser intensity measurement according to claim 3, characterized in that: A protective cover (8) is provided at the front end of the laser output terminal (7).

5. The wind turbine blade icing monitoring system based on laser intensity measurement according to claim 1, characterized in that: The wavelength of the laser emitted by the circular laser beam generation system is 10 -2 ~ 10 -1 µm.

6. The wind turbine blade icing monitoring system based on laser intensity measurement according to claim 1, characterized in that: The data processing and analysis system comprises an oscilloscope (17), a signal processor (12) and a computer (13); the first light intensity measuring instrument (4) and the second light intensity measuring instrument (9) are respectively connected to the oscilloscope (17); the oscilloscope (17) is connected to the signal processor (12); and the signal processor (12) is connected to the computer (13).

7. A method for monitoring fan blade icing using the fan blade icing monitoring system based on laser intensity measurement as claimed in any one of claims 1 to 6, characterized in that: include: The circular laser beam generating system emits a circular laser beam (10), the light intensity of which is measured by a first light intensity measuring instrument (4) and then transmitted to a second light intensity measuring instrument (9) via an optical fiber transmission system. When an ice layer (16) is formed in an ice monitoring area between an output end of the optical fiber transmission system and the second light intensity measuring instrument (9), a data processing and analysis system monitors the icing of the wind turbine blades based on changes in light intensity values ​​measured by the first light intensity measuring instrument (4) and the second light intensity measuring instrument (9) and in combination with time development characteristics.

Images