A method and device for testing the bending moment of wind turbine blades taking into account orthogonal effects

Abstract

The present invention relates to a method and device for testing the bending moment of a wind turbine blade taking into account orthogonal influences, comprising: obtaining a voltage signal of a flapping bending moment and a voltage signal of a shimming bending moment of a wind turbine blade; determining the flapping bending moment and the shimming bending moment of the wind turbine blade according to the voltage signal of the flapping bending moment and the voltage signal of the shimming bending moment of the wind turbine blade; the present invention obtains the flapping bending moment and the shimming bending moment based on the voltage signal of the flapping bending moment and the voltage signal of the shimming bending moment, taking into account the orthogonal sensitive influence between shimming and flapping, so that the test result is more accurate and reliable.

Description

Technical Field

[0001] The invention relates to the technical field of product detection and control of wind turbines, and in particular to a method and device for testing the bending moment of wind turbine blades taking orthogonal effects into account. Background Art

[0002] With the development of large-scale wind turbines, the increase in the size of wind turbine blades is particularly obvious. When the length of the blade increases, the bending moment at the root of the blade also increases, and the damage rate of the blade will increase. To this end, it is necessary to ensure that the blade strength and its dynamic performance meet the design requirements to ensure the long-term and reliable operation of the unit. The blade bending moment test generally only measures the swing and flapping bending moment at the root of the blade, which is also the most important part of the design bending moment of the wind turbine and directly affects the fatigue life of the blade. The blade bending moment test is an important method to ensure the service life of the blade, and it is also an indispensable part of the type test.

[0003] In the blade bending moment test, the rationality of the calibration method of the blade bending moment and the test voltage (or current) signal directly affects the accuracy of the bending moment test results. In the test, the voltage signal at the position of the strain gauge is usually collected to complete the bending moment test, but the actual strain position may not be in the swing direction and the swing direction, resulting in the swing bending moment affecting the swing bending moment, and the swing bending moment affecting the swing bending moment, that is, the generation of orthogonal sensitivity, resulting in the final bending moment accuracy is low. Summary of the invention

[0004] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a method and device for testing the bending moment of wind turbine blades taking into account orthogonal effects, wherein the flapping bending moment and the swing bending moment are obtained based on the voltage signal of the flapping bending moment and the voltage signal of the swing bending moment, taking into account the orthogonal sensitive effects between swing and flapping, thereby making the test results more accurate and reliable.

[0005] The purpose of the present invention is achieved by adopting the following technical solutions:

[0006] The present invention provides a method for testing the bending moment of a wind turbine blade taking into account orthogonal effects, wherein the method comprises:

[0007] Obtaining voltage signals of flapping bending moment and shimmying bending moment of wind turbine blades;

[0008] The flapping bending moment and the shimmy bending moment of the wind turbine blade are determined according to the voltage signal of the flapping bending moment and the voltage signal of the shimmy bending moment of the wind turbine blade.

[0009] Preferably, the step of obtaining the voltage signal of the flapping bending moment and the voltage signal of the shimmying bending moment of the wind turbine blade includes:

[0010] Collecting voltage signals of strain gauges located in the flapping direction and the swinging direction of the wind turbine blades;

[0011] The voltage signal of the strain gauge in the flapping direction and the voltage signal of the strain gauge in the swinging direction are isolated and amplified respectively to obtain the voltage signal of the flapping bending moment and the voltage signal of the swing bending moment of the wind turbine blade.

[0012] Furthermore, the distance between the longitudinal section where the strain gauge in the flapping direction and the strain gauge in the swinging direction are located and the root flange of the wind turbine blade is greater than 0.4D;

[0013] Where D is the diameter of the cross section of the wind turbine blade root.

[0014] Further, the determining of the flapping bending moment and the shimmy bending moment of the wind turbine blade according to the voltage signal of the flapping bending moment and the voltage signal of the shimmy bending moment of the wind turbine blade comprises:

[0015] Determine the flapping bending moment M of the wind turbine blades according to the following formula flap and the shimmying bending moment M edge :

[0016]

[0017] Where U flap is the voltage signal of swinging bending moment, U edge is the voltage signal of the shimmy bending moment, A1 is the first calibration coefficient, A2 is the second calibration coefficient, A3 is the third calibration coefficient, A4 is the fourth calibration coefficient, offset _flap is the swinging bending moment deviation, offset _edge is the shimmy bending moment deviation.

[0018] Furthermore, the first calibration coefficient A1, the second calibration coefficient A2, the third calibration coefficient A3 and the fourth calibration coefficient A4 are determined according to the following formula:

[0019]

[0020] Where U flap_max is the maximum voltage signal of the swinging moment, U flap_min is the minimum voltage signal of the swinging moment, U edge_max is the maximum voltage signal of the shimmy bending moment, U edge_min is the minimum voltage signal of the shimmy bending moment, M G is the gravity bending moment of the longitudinal section where the strain gauge is located.

[0021] Furthermore, the gravity bending moment M of the longitudinal section where the strain gauge is located is determined by the following formula: G :

[0022] M G =GL

[0023] Where G is the weight of the blade, and L is the distance between the center of gravity of the blade and the longitudinal section where the strain gauge is located.

[0024] Further, the flapping moment deviation offset is determined by the following formula: _flap and shimmy bending moment offset _edge :

[0025]

[0026] Where U flap_max is the maximum voltage signal of the swinging moment, U flap_min is the minimum voltage signal of the swinging moment, U edge_max is the maximum voltage signal of the shimmy bending moment, U edge_min is the minimum value of the voltage signal of the shimmying bending moment.

[0027] Based on the same inventive concept, the present invention also provides a wind turbine blade bending moment test device taking into account orthogonal effects, wherein the device comprises:

[0028] An acquisition unit, used for acquiring a voltage signal of a flapping bending moment and a voltage signal of a shimmying bending moment of a blade of a wind turbine;

[0029] The testing unit is used to determine the flapping bending moment and the shimmy bending moment of the wind turbine blade according to the voltage signal of the flapping bending moment and the voltage signal of the shimmy bending moment of the wind turbine blade.

[0030] Preferably, the acquisition unit is specifically used for:

[0031] Collecting voltage signals of strain gauges located in the flapping direction and the swinging direction of the wind turbine blades;

[0032] The voltage signal of the strain gauge in the flapping direction and the voltage signal of the strain gauge in the swinging direction are isolated and amplified respectively to obtain the voltage signal of the flapping bending moment and the voltage signal of the swing bending moment of the wind turbine blade.

[0033] Furthermore, the testing unit is specifically used for:

[0034] Determine the flapping bending moment M of the wind turbine blades according to the following formula flap and the shimmying bending moment M edge :

[0035]

[0036] Where U flap is the voltage signal of swinging bending moment, Uedge is the voltage signal of the shimmy bending moment, A1 is the first calibration coefficient, A2 is the second calibration coefficient, A3 is the third calibration coefficient, A4 is the fourth calibration coefficient, offset _flap is the swinging bending moment deviation, offset _edge is the shimmy bending moment deviation.

[0037] Compared with the closest prior art, the present invention has the following beneficial effects:

[0038] The present invention provides a method and device for testing the bending moment of a wind turbine blade taking into account the orthogonal influence, comprising: obtaining a voltage signal of a flapping bending moment and a voltage signal of a shimming bending moment of a wind turbine blade; determining the flapping bending moment and the shimming bending moment of the wind turbine blade according to the voltage signal of the flapping bending moment and the voltage signal of the shimming bending moment of the wind turbine blade; the present invention obtains the flapping bending moment and the shimming bending moment based on the voltage signal of the flapping bending moment and the voltage signal of the shimming bending moment, taking into account the orthogonal sensitive influence between shimming and flapping, so that the test result is more accurate and reliable;

[0039] When obtaining the voltage signals of the flapping bending moment and the swing bending moment of the wind turbine blade, the distance limit between the strain gauge position and the flange position at the root of the blade is set to avoid the influence of the local stress of the flange on the test results. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a flow chart of a method for testing the bending moment of a wind turbine blade taking into account orthogonal effects of the present invention;

[0041] Figure 2 Schematic diagram of strain gauge pasting in an embodiment of the present invention;

[0042] Figure 3 It is a schematic diagram of a wind turbine blade bending moment testing device taking orthogonal effects into account according to the present invention. DETAILED DESCRIPTION

[0043] The specific implementation modes of the present invention will be further described in detail below in conjunction with the accompanying drawings.

[0044] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] The present invention provides a method for testing the bending moment of a wind turbine blade taking into account the orthogonal influence. Figure 1As shown, the method includes:

[0046] Obtaining voltage signals of flapping bending moment and shimmying bending moment of wind turbine blades;

[0047] The flapping bending moment and the shimmy bending moment of the wind turbine blade are determined according to the voltage signal of the flapping bending moment and the voltage signal of the shimmy bending moment of the wind turbine blade.

[0048] In order to more clearly illustrate the purpose of the present invention, the present invention is further described below in conjunction with specific embodiments.

[0049] In the above embodiment of the present invention, the above-mentioned method of obtaining the voltage signal of the flapping bending moment and the voltage signal of the swing bending moment of the wind turbine blade includes:

[0050] Collecting voltage signals of strain gauges located in the flapping direction and the swinging direction of the wind turbine blades;

[0051] The voltage signal of the strain gauge in the flapping direction and the voltage signal of the strain gauge in the swinging direction are isolated and amplified respectively to obtain the voltage signal of the flapping bending moment and the voltage signal of the swing bending moment of the wind turbine blade.

[0052] Specifically, in the embodiments, Figure 2 As shown in a, the strain gauges in the swing direction and the strain gauges in the swing direction are pre-set, and the traditional Wheatstone bridge method of pasting resistance strain gauges is adopted to realize the strain measurement of the measured position, and as shown in Figure 2 As shown in b, the distance L0 between the longitudinal section where the strain gauge is located and the root flange of the wind turbine blade is greater than 0.4D, where D is the diameter of the root cross section of the wind turbine blade. At the same time, in order to reduce the influence of external environmental factors on the test results, the strain gauge has been treated with moisture-proof treatment.

[0053] Those skilled in the art know that the key to blade bending moment testing is to determine the relationship between the collected voltage signal and the actual bending moment, that is, the following formula:

[0054] M=slope*U+offset

[0055] Where, M is the bending moment; U is the voltage signal, slope is the slope, and offset is the deviation;

[0056] However, in specific working conditions, the actual strain position may not be in the swing direction and flapping direction of the strain gauge, which causes the swing bending moment to affect the flapping bending moment, and the flapping bending moment to affect the swing bending moment, that is, the generation of orthogonal sensitivity. Therefore, it is necessary to determine the orthogonal sensitive relationship between the flapping and swing bending moment signals to correct the bending moment. The calibration coefficient should satisfy the following formula:

[0057]

[0058] Where A1 is the first calibration coefficient, A2 is the second calibration coefficient, A3 is the third calibration coefficient, A4 is the fourth calibration coefficient, and U flap is the voltage signal of swinging bending moment, U edge is the voltage signal of the shimmying bending moment, M edge 、M flap They are shimmy and flapping bending moments respectively.

[0059] Therefore, in the above embodiment of the present invention, the above-mentioned determination of the flapping bending moment and the shimmying bending moment of the wind turbine blade according to the voltage signal of the flapping bending moment and the voltage signal of the shimmying bending moment of the wind turbine blade includes:

[0060] Determine the flapping bending moment M of the wind turbine blades according to the following formula flap and the shimmying bending moment M edge :

[0061]

[0062] Where U flap is the voltage signal of swinging bending moment, U edge is the voltage signal of the shimmy bending moment, A1 is the first calibration coefficient, A2 is the second calibration coefficient, A3 is the third calibration coefficient, A4 is the fourth calibration coefficient, offset _flap is the swinging bending moment deviation, offset _edge is the shimmy bending moment deviation.

[0063] The known calculation formulas for flapping bending moment and shimmying bending moment are as follows:

[0064]

[0065] In the formula, θ e is the blade pitch angle, θ f is the blade rotation azimuth, M G is the gravity bending moment of the longitudinal section where the strain gauge is located.

[0066] Therefore, in an embodiment of the present invention, the first calibration coefficient A1, the second calibration coefficient A2, the third calibration coefficient A3, the fourth calibration coefficient A4, the flapping moment deviation offset _flap and shimmy bending moment offset _edge , the specific steps are as follows:

[0067] 1) In light wind conditions, fix the blade pitch angle to 0° and idle the unit for 2-3 turns.

[0068] θ e =0°, M flap =0, then

[0069] Then we can get,

[0070] 2) In light wind conditions, fix the blade pitch angle to 90° and crank the unit 2-3 times.

[0071] θ e =90°, M edge =0, then

[0072] Then we can get,

[0073] 3) In light wind conditions, fix the blade pitch angle to 45° and crank the unit 2-3 times.

[0074] θ e =45°, Then there is and

[0075] Then we can get, and

[0076] 4) When the flapping bending moment reaches the maximum, the following formula is obtained:

[0077]

[0078] When the flapping bending moment reaches the minimum, the following formula is obtained:

[0079]

[0080] Due to M flap_max =-M flap_min and M edge_max =-M edge_min , therefore, we can get:

[0081]

[0082] Among them, U flap_max is the maximum voltage signal of the swinging moment, U flap_min is the minimum voltage signal of the swinging moment, U edge_max is the maximum voltage signal of the shimmy bending moment, U edge_min is the minimum voltage signal of the shimmy bending moment, M G is the gravity bending moment of the longitudinal section where the strain gauge is located.

[0083] In the embodiment of the present invention, in order to make the final result more accurate, the maximum value and the minimum value of the voltage signal are both average values ​​of more than three times.

[0084] Furthermore, the gravity bending moment M of the longitudinal section where the strain gauge is located is determined by the following formula: G :

[0085] M G =GL

[0086] Where G is the weight of the blade, and L is the distance between the center of gravity of the blade and the longitudinal section where the strain gauge is located.

[0087] Based on the same inventive concept, the present invention also provides a wind turbine blade bending moment test device taking into account orthogonal effects, such as Figure 3 As shown, the device comprises:

[0088] An acquisition unit, used for acquiring a voltage signal of a flapping bending moment and a voltage signal of a shimmying bending moment of a blade of a wind turbine;

[0089] The testing unit is used to determine the flapping bending moment and the shimmy bending moment of the wind turbine blade according to the voltage signal of the flapping bending moment and the voltage signal of the shimmy bending moment of the wind turbine blade.

[0090] Preferably, the acquisition unit is specifically used for:

[0091] Collecting voltage signals of strain gauges located in the flapping direction and the swinging direction of the wind turbine blades;

[0092] The voltage signal of the strain gauge in the flapping direction and the voltage signal of the strain gauge in the swinging direction are isolated and amplified respectively to obtain the voltage signal of the flapping bending moment and the voltage signal of the swing bending moment of the wind turbine blade.

[0093] Furthermore, the testing unit is specifically used for:

[0094] Determine the flapping bending moment M of the wind turbine blades according to the following formula flap and the shimmying bending moment M edge :

[0095]

[0096] Where U flap is the voltage signal of swinging bending moment, U edge is the voltage signal of the shimmy bending moment, A1 is the first calibration coefficient, A2 is the second calibration coefficient, A3 is the third calibration coefficient, A4 is the fourth calibration coefficient, offset _flap is the swinging bending moment deviation, offset _edge is the shimmy bending moment deviation.

[0097] Furthermore, the distance between the longitudinal section where the strain gauge in the flapping direction and the strain gauge in the swinging direction are located and the root flange of the wind turbine blade is greater than 0.4D;

[0098] Where D is the diameter of the cross section of the wind turbine blade root.

[0099] Furthermore, the first calibration coefficient A1, the second calibration coefficient A2, the third calibration coefficient A3 and the fourth calibration coefficient A4 are determined according to the following formula:

[0100]

[0101] Where U flap_max is the maximum voltage signal of the swinging moment, U flap_min is the minimum voltage signal of the swinging moment, U edge_max is the maximum voltage signal of the shimmy bending moment, U edge_min is the minimum voltage signal of the shimmy bending moment, M G is the gravity bending moment of the longitudinal section where the strain gauge is located.

[0102] Furthermore, the gravity bending moment M of the longitudinal section where the strain gauge is located is determined by the following formula: G :

[0103] M G =GL

[0104] Where G is the weight of the blade, and L is the distance between the center of gravity of the blade and the longitudinal section where the strain gauge is located.

[0105] Further, the flapping moment deviation offset is determined by the following formula: _flap and shimmy bending moment offset _edge :

[0106]

[0107] Where U flap_max is the maximum voltage signal of the swinging moment, U flap_min is the minimum voltage signal of the swinging moment, U edge_max is the maximum voltage signal of the shimmy bending moment, U edge_min is the minimum value of the voltage signal of the shimmying bending moment.

[0108] In summary, the present invention provides a method and device for testing the bending moment of a wind turbine blade taking into account the orthogonal influence, comprising: obtaining a voltage signal of a flapping bending moment and a voltage signal of a shimming bending moment of a wind turbine blade; determining the flapping bending moment and the shimming bending moment of the wind turbine blade according to the voltage signal of the flapping bending moment and the voltage signal of the shimming bending moment of the wind turbine blade; the present invention obtains the flapping bending moment and the shimming bending moment based on the voltage signal of the flapping bending moment and the voltage signal of the shimming bending moment, taking into account the orthogonal sensitive influence between shimming and flapping, so that the test result is more accurate and reliable;

[0109] When obtaining the voltage signals of the flapping bending moment and the swing bending moment of the wind turbine blade, the distance limit between the strain gauge position and the flange position at the root of the blade is set to avoid the influence of the local stress of the flange on the test results.

[0110] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0111] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0112] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0113] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0114] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for testing the bending moment of a wind turbine blade taking into account orthogonal effects, characterized in that: The method comprises: Obtaining voltage signals of flapping bending moment and shimmying bending moment of wind turbine blades; Determine the flapping bending moment and the shimmy bending moment of the wind turbine blade according to the voltage signal of the flapping bending moment and the voltage signal of the shimmy bending moment of the wind turbine blade; The method of determining the flapping bending moment and the shimmying bending moment of the wind turbine blade according to the voltage signal of the flapping bending moment and the voltage signal of the shimmying bending moment of the wind turbine blade comprises: Determine the flapping bending moment M of the wind turbine blades according to the following formula flap and the shimmying bending moment M edge : Where U flap is the voltage signal of the swinging bending moment, U edge is the voltage signal of the shimmy bending moment, A1 is the first calibration coefficient, A2 is the second calibration coefficient, A3 is the third calibration coefficient, A4 is the fourth calibration coefficient, offset _flap is the swinging bending moment deviation, offset _edge is the shimmy bending moment deviation; The first calibration coefficient A1, the second calibration coefficient A2, the third calibration coefficient A3, the fourth calibration coefficient A4, the flapping moment deviation offset and the blade pitch angle calibration method are determined. _flap and shimmy bending moment offset _edge , the specific steps are as follows: In light wind conditions, fix the blade pitch angle to 0° and idle the unit for 2-3 turns. θ e =0°, M flap =0, then Then we can get, In light wind conditions, fix the blade pitch angle to 90° and crank the unit 2-3 times. θ e =90°, M edge =0, then Then we can get, In light wind conditions, fix the blade pitch angle to 45° and crank the unit 2-3 times. θ e =45°, Then there is Then we can get, and When the flapping bending moment reaches the maximum, the following formula is obtained: When the flapping bending moment reaches the minimum, the following formula is obtained: Based on M flap_max =-M flap_min and M edge_max =-M edge_min , determine the flapping moment deviation offset _flap and shimmy bending moment offset _edge : Where U flap_max is the maximum voltage signal of the swinging moment, U flap_min is the minimum voltage signal of the swinging moment, U edge_max is the maximum voltage signal of the shimmy bending moment, U edge_min is the minimum voltage signal of the shimmy bending moment, M G is the gravity bending moment.

2. The method according to claim 1, characterized in that The step of obtaining the voltage signal of the flapping bending moment and the voltage signal of the shimmying bending moment of the wind turbine blade comprises: Collecting voltage signals of strain gauges located in the flapping direction and the swinging direction of the wind turbine blades; The voltage signal of the strain gauge in the flapping direction and the voltage signal of the strain gauge in the swinging direction are isolated and amplified respectively to obtain the voltage signal of the flapping bending moment and the voltage signal of the swing bending moment of the wind turbine blade.

3. The method according to claim 2, characterized in that The distance between the longitudinal section where the strain gauge in the flapping direction and the strain gauge in the swinging direction are located and the root flange of the wind turbine blade is greater than 0.4D; Where D is the diameter of the cross section of the wind turbine blade root.

4. The method according to claim 2, characterized in that Determine the gravity bending moment M of the longitudinal section where the strain gauge is located by the following formula: G : M G =GL Where G is the weight of the blade, and L is the distance between the center of gravity of the blade and the longitudinal section where the strain gauge is located.

5. A wind turbine blade bending moment test device taking into account orthogonal effects, characterized in that: The device comprises: An acquisition unit, used for acquiring a voltage signal of a flapping bending moment and a voltage signal of a shimmying bending moment of a blade of a wind turbine; A testing unit, used for determining the flapping bending moment and the shimmy bending moment of the wind turbine blade according to the voltage signal of the flapping bending moment and the voltage signal of the shimmy bending moment of the wind turbine blade; The testing unit is specifically used for: Determine the flapping bending moment M of the wind turbine blades according to the following formula flap and the shimmying bending moment M edge : Where U flap is the voltage signal of the swinging bending moment, U edge is the voltage signal of the shimmy bending moment, A1 is the first calibration coefficient, A2 is the second calibration coefficient, A3 is the third calibration coefficient, A4 is the fourth calibration coefficient, offset _flap is the swinging bending moment deviation, offset _edge is the shimmy bending moment deviation; The first calibration coefficient A1, the second calibration coefficient A2, the third calibration coefficient A3, the fourth calibration coefficient A4, the flapping moment deviation offset and the blade pitch angle calibration method are determined. _flap and shimmy bending moment offset _edge , the specific steps are as follows: In light wind conditions, fix the blade pitch angle to 0° and idle the unit for 2-3 turns. θ e =0°, M flap =0, then Then we can get, In light wind conditions, fix the blade pitch angle to 90° and crank the unit 2-3 times. θ e =90°,°M edge =0, then Then we can get, In light wind conditions, fix the blade pitch angle to 45° and crank the unit 2-3 times. θ e =45 ° , Then there is Then we can get, and When the flapping bending moment reaches the maximum, the following formula is obtained: When the flapping bending moment reaches the minimum, the following formula is obtained: Based on M flap_max =-M flap_min and M edge_max =-M edge_min , determine the flapping moment deviation offset _flap and shimmy bending moment offset _edge : Where U flap_max is the maximum voltage signal of the swinging moment, U flap_min is the minimum voltage signal of the swinging moment, U edge_max is the maximum voltage signal of the shimmy bending moment, U edge_min is the minimum voltage signal of the shimmy bending moment, M G is the gravity bending moment.

6. The device according to claim 5, characterized in that The acquisition unit is specifically used for: Collecting voltage signals of strain gauges located in the flapping direction and the swinging direction of the wind turbine blades; The voltage signal of the strain gauge in the flapping direction and the voltage signal of the strain gauge in the swinging direction are isolated and amplified respectively to obtain the voltage signal of the flapping bending moment and the voltage signal of the swing bending moment of the wind turbine blade.

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