Fan load measuring system and fan

Abstract

The invention provides a fan load measuring system and a fan. The fan load measuring system comprises a plurality of optical fiber load sensors which are arranged at the root of the same target blade; the temperature sensors are arranged close to the optical fiber load sensors and are in one-to-one correspondence with the optical fiber load sensors; and the load metering unit is used for collecting real-time measurement data of the optical fiber load sensor and the temperature sensor and calculating the load of the target blade based on the calibration parameters of the target blade. According to the invention, the temperature sensor is integrated in the measurement system to compensate the measurement error, thereby improving the parameter calibration precision, and finally improving the real-time measurement accuracy of the load.

Description

Technical Field

[0001] This invention relates to the field of measurement technology, specifically to a wind turbine load measurement system and a wind turbine. Background Technology

[0002] Real-time wind turbine load acquisition is crucial for wind turbine control. Related technologies use various sensors to calibrate the blade load system and employ algorithms to obtain the real-time blade load. However, all these sensors have measurement errors, especially under temperature variations, where they exhibit nonlinear changes or drift, making the measurement results unsuitable for practical applications. In scenarios with excessively large errors, wind turbine control failures and damage can even occur. Therefore, eliminating or reducing the impact of temperature on the accuracy of wind turbine load measurement is an urgent problem to be solved. Summary of the Invention

[0003] To overcome at least one of the many problems in related technologies, a first aspect of the present invention provides a wind turbine load measurement system, comprising:

[0004] The fiber optic load sensor comprises multiple sensors and is located at the root of the same target blade.

[0005] A temperature sensor is disposed adjacent to the fiber optic load sensor and corresponds one-to-one with the fiber optic load sensor.

[0006] The load measurement unit collects real-time measurement data from the fiber optic load sensor and temperature sensor, and calculates the load on the target blade based on the calibration parameters of the target blade.

[0007] In some optional embodiments, the fiber optic load sensor provides feedback on the wavelength measurement value under load, and the temperature sensor is used to perform temperature compensation on its corresponding fiber optic load sensor.

[0008] In some optional embodiments, the fiber optic load sensor comprises four sensors, which are distributed at 90-degree intervals at the root of the target leaf.

[0009] In some alternative embodiments, at least one of the fiber load sensors is positioned below the mold opening of the target blade.

[0010] In some optional embodiments, the calibration parameters of the target blade include an intermediate coefficient matrix and a center wavelength matrix of each fiber optic load sensor.

[0011] In some optional embodiments, the calibration parameters of the target blade are obtained by controlling the target blade under multiple different operating conditions.

[0012] In some optional embodiments, the multiple sets of different operating conditions are achieved by adjusting the azimuth angle and pitch angle of the target blade.

[0013] In some alternative embodiments, the load on the target blade includes at least one of flapping moment and oscillation moment.

[0014] In some optional embodiments, the state parameters of the target blade include the blade cone angle and the blade tilt angle, and the intermediate coefficient matrix is ​​at least related to the blade cone angle and the blade tilt angle.

[0015] In some optional embodiments, temperature sensor measurements are collected, and the accuracy of wind turbine load measurement is improved by using a dual-wavelength method.

[0016] A second aspect of the present invention provides a wind turbine, including a wind turbine load measurement system according to any one of the first aspects of the present invention.

[0017] The technical solution of the present invention has the following advantages or beneficial effects:

[0018] This invention places a temperature sensor near the fiber optic load sensor, with a one-to-one correspondence between the two types of sensors. Simultaneously, a load measurement unit collects real-time measurement data from both the fiber optic load sensor and the temperature sensor, and calculates the load on the target blade based on its calibration parameters. Ultimately, temperature compensation compensates for the measurement error of the fiber optic load sensor, improving the calibration accuracy of the blade calibration parameters and the measurement precision of the wind turbine blade load. Attached Figure Description

[0019] The accompanying drawings are provided to better understand the invention and are not intended to unduly limit the scope of the invention. Wherein:

[0020] Figure 1 This is a schematic diagram of the sensor installation position of the load measurement system according to an embodiment of the present invention;

[0021] Figure 2 This is a schematic diagram illustrating the sensor installation details according to an embodiment of the present invention. Detailed Implementation

[0022] The following description, in conjunction with the accompanying drawings, illustrates exemplary embodiments of the present invention, including various details to aid understanding. These details should be considered merely exemplary. Therefore, those skilled in the art will recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the invention. Similarly, for clarity and brevity, descriptions of well-known functions and structures are omitted in the following description.

[0023] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The singular forms “a,” “the,” and “the” used in this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0024] It should be understood that although the terms first, second, third, etc., may be used in this application to describe various information, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, without departing from the scope of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to determination."

[0025] As described in the background section, in the prior art, all kinds of sensors used for wind turbine load measurement have measurement errors. Especially under temperature changes, the sensors exhibit nonlinear changes or nonlinear drift, making it difficult for the measurement results to meet the actual use requirements.

[0026] To address the aforementioned technical problems, the first aspect of this invention provides a wind turbine load measurement system, comprising: a plurality of fiber optic load sensors disposed at the root of the same target blade; a temperature sensor disposed adjacent to the fiber optic load sensors and corresponding one-to-one with each fiber optic load sensor; and a load measurement unit that collects real-time measurement data from the fiber optic load sensors and the temperature sensor, and calculates the load of the target blade based on the calibration parameters of the target blade.

[0027] like Figure 1In the illustrated embodiment, the present invention uses multiple sensors at the root of the blade to measure the load on the wind turbine blade. Typically, the load factor of the blade needs to be calibrated first, and then the real-time load is calculated by combining the real-time measurement point parameters of the sensors with the relevant load system. To improve the calibration accuracy of the load factor (or load parameter, calibration parameter, calibration coefficient, etc.), the fiber optic load sensor is often selected as a fiber optic grating sensor. However, because fiber optic gratings are sensitive to temperature, the measurement accuracy is difficult to meet the application requirements. Therefore, the present invention introduces temperature compensation technology to improve the measurement accuracy and reliability of the fiber optic load sensor. Specifically, a combination 101 of fiber optic load sensor and temperature sensor can be installed at the root of the blade. Since there are often multiple sets of wind turbine blades, corresponding fiber optic load sensors and temperature sensors can be set on each set of blades during measurement. In practice, when the fiber optic load sensor is subjected to a load, the load causes stress changes inside the fiber optic grating. This stress change alters the period or core refractive index of the fiber optic grating, thereby causing a change in the center wavelength of the fiber optic grating. Specifically, increasing the load compresses the fiber grating, shortening its period or changing the core refractive index, causing the center wavelength to shift towards shorter wavelengths (i.e., blue shift); conversely, decreasing the load shifts the center wavelength towards longer wavelengths (i.e., red shift). Fiber optic load sensors infer the load magnitude by measuring the change in the center wavelength of the fiber grating before and after the load is applied. Specifically, the measurement system first records the initial center wavelength of the fiber grating, and then monitors the change in center wavelength in real time under load. Based on the change in center wavelength and the known sensing coefficient (i.e., the change in center wavelength per unit load), the load magnitude can be calculated. Correspondingly, the temperature effect on fiber optic load sensors includes the following mechanisms: Thermal expansion effect: Fiber optic materials (such as fused silica) have thermal expansion properties; as the temperature rises or falls, the length and diameter of the fiber change. This change directly affects the period and refractive index of the fiber grating, leading to a shift in its center wavelength. Thermo-optic effect: Temperature changes also cause changes in the refractive index of the fiber material, which also affects the center wavelength of the fiber grating. Temperature Sensitivity: Fiber optic load sensors are highly sensitive to temperature; even minute temperature changes can cause significant wavelength shifts. Therefore, this invention places multiple fiber optic load sensors at the root of a selected target blade. Correspondingly, multiple temperature sensors are also present, positioned adjacent to and corresponding one-to-one with the fiber optic load sensors. This proximity of the temperature sensors to the fiber optic load sensors maximizes the feedback of their temperature values ​​and eliminates measurement errors caused by temperature variations through temperature compensation, ultimately improving the load calibration accuracy.In addition, the load measurement system of the present invention also integrates a load measurement unit, which collects real-time measurement data from the fiber optic load sensor and temperature sensor, and calculates the load on the target blade based on the calibration parameters of the target blade.

[0028] In some optional embodiments, the fiber optic load sensor provides feedback on the wavelength measurement value under load, and the temperature sensor is used to perform temperature compensation on its corresponding fiber optic load sensor. For example... Figure 2 In the illustrated embodiment, multiple temperature sensors 202 and fiber optic load sensors 201 are disposed between the trailing edge 203 and the leading edge 204 of the blade. To improve the temperature compensation effect, the temperature sensors can be selected as fiber Bragg grating temperature sensors. Multiple accurately temperature-measuring fiber Bragg grating temperature sensors are placed at the root of the blade under test. Since the fiber optic load sensors and fiber Bragg grating temperature sensors are in the same temperature environment, the temperature measured by the fiber Bragg grating temperature sensors can be considered as the temperature of the fiber optic load sensors. By subtracting the influence of temperature on the reflected wavelength from the formula for the change in reflected wavelength, the accurate stress or strain value of the fiber optic load sensors is obtained, thereby achieving the purpose of temperature compensation.

[0029] In some optional embodiments, the fiber optic load sensors comprise four units, spaced 90 degrees apart at the root of the target blade. In practice, to improve load measurement and calibration accuracy, multi-directional blade monitoring is necessary. Specifically, the blade is subjected to loads in multiple directions during operation, including flapping (perpendicular to the blade chord) and oscillation (parallel to the blade chord). Therefore, placing four fiber optic load sensors at the blade root ensures accurate monitoring of loads in these two primary directions. Furthermore, adding more fiber optic load sensors achieves redundancy. By increasing the number of sensors, redundancy is achieved; even if one sensor fails, the others can continue operating, ensuring measurement continuity and accuracy. Additionally, placing multiple sensors in the stress concentration area at the blade root allows for more comprehensive monitoring of the stress distribution at the blade root, enabling timely detection and warning of potential fatigue damage. Moreover, by placing sensors at different locations, stress data from different areas of the blade root can be acquired, allowing for a more accurate assessment of the overall stress condition of the blade. In this invention, the four sensor groups, spaced 90 degrees apart along the circumference at the blade root, ensure that each sensor can monitor load changes in a primary stress direction. In this way, regardless of the operating conditions of the blades, their stress situation can be captured comprehensively and accurately, thus accurately obtaining the stress situation of the blades.

[0030] In some optional embodiments, at least one of the fiber optic load sensors is positioned below the mold seam of the target blade. The mold seam refers to the joint formed during the manufacturing process of a wind turbine blade when the leading edge and back edge (or other parts) of the blade are joined together using a mold. The quality of this joint directly affects the overall strength, sealing performance, and appearance quality of the blade. The sealing performance of the mold seam directly affects the aerodynamic performance and durability of the blade. Poor sealing of the mold seam can lead to air leakage during operation, reducing the wind turbine's power generation efficiency and service life. The quality of the mold seam also relates to the overall strength of the blade. Defects or improper handling of the mold seam can cause the blade to easily break or be damaged under external forces. Therefore, to avoid interfering with the sealing performance and overall strength of the blade when installing the sensor, this invention positions at least one of the fiber optic load sensors below the mold seam of the target blade to avoid affecting the mold seam. Furthermore, this sensor can be used as a positioning reference, with other sensors evenly distributed along a clockwise or counterclockwise direction.

[0031] In some optional embodiments, the calibration parameters of the target blade include an intermediate coefficient matrix and a center wavelength matrix for each fiber optic load sensor. The intermediate coefficient matrix is ​​a crucial parameter in the calibration process, reflecting the relationship between the output signal of the fiber optic load sensor and the actual load on the blade. Furthermore, in the fiber optic load monitoring system, each fiber optic load sensor has a center wavelength (or zero-load wavelength), corresponding to the sensor's output wavelength in the no-load state. The center wavelength matrix is ​​a matrix formed by arranging the center wavelengths of all fiber optic load sensors in a specific order. This matrix plays a vital role in the calibration process because it provides a benchmark for subsequent data processing and analysis. For ease of calculation, this invention employs a mature load calculation method from the prior art, which will not be discussed further here. In practice, the corresponding load can be calculated simply by experimentally calibrating the intermediate coefficient matrix and the center wavelength matrix.

[0032] In some optional embodiments, the calibration parameters of the target blade are obtained by controlling the target blade under multiple different operating conditions. The wind turbine's operating state and stress conditions vary under different operating conditions. By calibrating the load coefficient under different operating conditions, the performance of the wind turbine under different conditions can be comprehensively reflected, including its load-bearing capacity, stability, and efficiency. This helps to more accurately evaluate the overall performance and reliability of the wind turbine. Furthermore, the calibration coefficient includes multiple parameters, and to solve for these parameters, it is necessary to control the blade under multiple different operating conditions. In some optional embodiments, the multiple different operating conditions are achieved by adjusting the azimuth angle and pitch angle of the target blade. The azimuth angle of the blade refers to the position angle of the blade in the rotor's rotation plane, used to describe the rotation angle of the blade relative to a fixed direction (such as the tower or rotor centerline). Changes in the azimuth angle cause the blade to experience different wind speeds and directions during rotor rotation, thus affecting the aerodynamic load distribution on the blade. The pitch angle, also known as the pitch angle, refers to the angle between the airfoil chord at the tip of the wind turbine blade and the rotation plane. This parameter is used to describe the degree of inclination of the blade relative to the rotor plane. Changes in the blade pitch angle directly affect the blade's angle of attack and the forces acting on it. The angle of attack is the angle between the blade chord and the incoming wind speed, which determines the magnitude and direction of the aerodynamic forces acting on the blade. Therefore, by changing one or both of the azimuth and pitch angle parameters, the load on the wind turbine blades can be altered, thus facilitating the calculation of calibration parameters.

[0033] In some optional embodiments, the load on the target blade includes at least one of flapping moment and shimmy moment. The flapping moment is the bending moment generated in the flapping direction (i.e., perpendicular to the rotor's plane of rotation) of the wind turbine blade during rotation due to changes in wind speed, direction, and other factors. This bending moment causes bending deformation of the blade in the flapping direction. The flapping moment exhibits significant fluctuations and is easily affected by shear, turbulence, and other factors. Reducing the flapping moment of the blade is significant for improving wind turbine stability and extending blade lifespan. The shimmy moment is the bending moment generated in the shimmy direction (i.e., perpendicular to the flapping direction and along the blade's span) of the wind turbine blade during rotation. This bending moment causes bending deformation of the blade in the shimmy direction. Compared to the flapping moment, the shimmy moment typically has a smaller impact on blade operation. However, under certain operating conditions, such as hazardous conditions or when the blade is subjected to non-uniform airflow, the shimmy moment may increase significantly. Therefore, in order to fully reflect the state of the wind turbine blades, the present invention must obtain at least one of the flapping moment and the swaying moment to provide reliable parameters for the control of the blades or the wind turbine.

[0034] In some optional embodiments, the state parameters of the target blade include the blade cone angle and the blade tilt angle, and the intermediate coefficient matrix is ​​at least related to the blade cone angle and the blade tilt angle.

[0035] In some optional embodiments, temperature sensor measurements are acquired, and the accuracy of wind turbine load measurement is improved using a dual-wavelength method. The basic principle of a dual-wavelength fiber optic load sensor is based on the wavelength modulation characteristics of fiber optic gratings. A fiber optic grating is an optical fiber structure with a periodic refractive index change. When light waves propagate in the fiber, those satisfying the Bragg condition are reflected back, forming a specific reflection spectrum. By measuring the change in a specific wavelength in the reflection spectrum, physical quantities can be measured. The dual-wavelength fiber optic load sensor utilizes two fiber optic gratings of different wavelengths, each corresponding to a different physical quantity or addressing cross-sensitivity issues. For temperature compensation applications, a dual-wavelength fiber optic load sensor is used, with one wavelength sensitive to strain and the other sensitive to temperature. By simultaneously monitoring the changes in these two wavelengths, separate measurements of strain and temperature can be achieved, thus enabling temperature compensation.

[0036] A second aspect of the present invention provides a wind turbine, including a wind turbine load measurement system according to any one of the first aspects of the present invention.

[0037] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art, after considering the specification and practicing the technical solutions disclosed in this application, will readily conceive of other embodiments of this disclosure. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary technical means in the art not disclosed in this disclosure. The specification and embodiments are considered exemplary only, and the true scope and spirit of this disclosure are indicated by the following claims.

[0038] It should be understood that this disclosure is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this disclosure is limited only by the appended claims.

Claims

1. A wind turbine load measurement system, characterized in that: include: The fiber optic load sensor comprises multiple sensors, all located at the root of the same target blade. A temperature sensor is disposed adjacent to the fiber optic load sensor and corresponds one-to-one with the fiber optic load sensor. The load measurement unit collects real-time measurement data from the fiber optic load sensor and temperature sensor, and calculates the load on the target blade based on the calibration parameters of the target blade.

2. The wind turbine load measurement system according to claim 1, characterized in that, The optical fiber load sensor provides feedback on the wavelength measurement value under load, and the temperature sensor is used to perform temperature compensation on its corresponding optical fiber load sensor.

3. The wind turbine load measurement system according to claim 1, characterized in that, The fiber optic load sensor comprises four units, which are distributed at 90-degree intervals at the root of the target leaf.

4. The wind turbine load measurement system according to claim 1, characterized in that, At least one of the aforementioned fiber optic load sensors is positioned below the mold gap of the target blade.

5. The wind turbine load measurement system according to any one of claims 1 to 4, characterized in that, The calibration parameters for the target blade include an intermediate coefficient matrix and a center wavelength matrix for each fiber optic load sensor.

6. The wind turbine load measurement system according to claim 5, characterized in that, The calibration parameters of the target blade are obtained by controlling the target blade under multiple different operating conditions.

7. The wind turbine load measurement system according to claim 6, characterized in that, The various operating conditions are achieved by adjusting the azimuth angle and pitch angle of the target blade.

8. The wind turbine load measurement system according to claim 7, characterized in that, The load on the target blade includes at least one of flapping moment and oscillation moment.

9. The wind turbine load measurement system according to claim 1, characterized in that, The temperature sensor measurements are collected, and the accuracy of wind turbine load measurement is improved by using a dual-wavelength method.

10. A wind turbine, comprising the wind turbine load measurement system according to any one of claims 1-9.

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