CN111677635A - A method and device for measuring the bending moment of wind turbine blades considering orthogonal effects - Google Patents

Abstract

The invention relates to a wind turbine generator blade bending moment testing method and device considering orthogonal influence, comprising the following steps of: acquiring voltage signals of blade flapping bending moment and voltage signals of shimmy bending moment of a wind turbine generator; 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 invention obtains the flapping bending moment and the shimmy bending moment based on the voltage signal of the flapping bending moment and the voltage signal of the shimmy bending moment, and takes the orthogonal sensitivity influence between shimmy and flapping into account, so that the test result is more accurate and reliable.

Description

A method and device for measuring the bending moment of wind turbine blades considering orthogonal effects

technical field

The invention relates to the technical field of product detection and control of wind turbines, in particular to a method and a device for measuring the bending moment of blades of wind turbines taking into account the orthogonal influence.

Background technique

With the development of large-scale wind turbines, the increase of blade size of wind turbines is particularly obvious. When the length of the blade increases, the bending moment on 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, so as to ensure long-term and reliable operation of the unit. The blade bending moment test generally only measures the sway and waving bending moment of the blade root, which is also the most important design bending moment of the wind turbine. part, which 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 inaccessible part of the type test.

In the blade bending moment test, whether the calibration method of the blade bending moment amount and the test voltage (or current) signal is reasonable or not directly affects the accuracy of the bending moment test results. In the test, the voltage signal of 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 position of the swing direction and the swing direction, resulting in the swing bending moment affecting the swing moment, and the swing bending moment affecting the swing Vibration bending moment, i.e. the generation of quadrature sensitivity, leads to lower accuracy of the resulting bending moment.

SUMMARY OF THE INVENTION

In view of the deficiencies of the prior art, the purpose of the present invention is to provide a method and device for measuring the bending moment of a wind turbine blade taking into account the orthogonal influence, and obtain the swing bending moment based on the voltage signal of the swing bending moment and the voltage signal of the sway bending moment. and the sway bending moment, taking into account the orthogonal sensitivity effect between sway and flapping, making the test results more accurate and reliable.

The purpose of this invention is to adopt following technical scheme to realize:

The present invention provides a method for measuring the bending moment of a wind turbine blade taking into account the orthogonal effect. The improvement lies in that the method includes:

Obtain the voltage signal of the waving bending moment and the voltage signal of the swaying bending moment of the wind turbine blade;

The swing bending moment and the sway bending moment of the wind turbine blade are determined according to the voltage signal of the swing bending moment and the voltage signal of the swing bending moment of the wind turbine blade.

Preferably, the acquiring the voltage signal of the swing bending moment and the voltage signal of the sway bending moment of the wind turbine blade includes:

Collect the voltage signal of the strain gauge in the swing direction and the voltage signal of the strain gauge in the swing direction inside the wind turbine blade;

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

Further, the distance between the longitudinal section of the strain gauge in the swing direction and the strain gauge in the swing direction and the flange at the root of the wind turbine blade is greater than 0.4D;

Among them, D is the diameter of the cross section of the root of the wind turbine blade.

Further, the determination of the swing bending moment and the swing bending moment of the wind turbine blade according to the voltage signal of the swing bending moment and the voltage signal of the swing bending moment of the wind turbine blade includes:

Determine the flapping moment M _flap and the swaying moment M _edge of the wind turbine blade as follows:

In the formula, U _flap is the voltage signal of the swing bending moment, U _edge is the voltage signal of the swing bending moment, A ₁ is the first calibration coefficient, A ₂ is the second calibration coefficient, A ₃ is the third calibration coefficient, A ₄ is the fourth calibration coefficient, offset _{_flap} is the deflection of the flapping moment, and offset _{_edge} is the deflection of the flutter moment.

Further, the first calibration coefficient A ₁ , the second calibration coefficient A ₂ , the third calibration coefficient A ₃ and the fourth calibration coefficient A ₄ are determined as follows:

In the formula, U _{flap_max} is the maximum voltage signal of the flapping moment, U _{flap_min} is the minimum voltage signal of the flapping moment, U _{edge_max} is the maximum voltage signal of the swing bending moment, and U _{edge_min} is the voltage signal of the swing bending moment The minimum value, _MG is the gravitational bending moment of the longitudinal section where the strain gauge is located.

Further, the gravitational bending moment M _G of the longitudinal section where the strain gauge is located is determined as follows:

M _G = GL

where G is the gravity 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.

Further, the flapping moment deviation offset _{_flap} and the sway bending moment deviation offset _{_edge} are determined as follows:

In the formula, U _{flap_max} is the maximum voltage signal of the flapping moment, U _{flap_min} is the minimum voltage signal of the flapping moment, U _{edge_max} is the maximum voltage signal of the swing bending moment, and U _{edge_min} is the voltage signal of the swing bending moment minimum value.

Based on the same inventive concept, the present invention also provides a device for testing the bending moment of a wind turbine blade that takes into account orthogonal effects, the improvement of which is that the device includes:

an acquisition unit, used to acquire the voltage signal of the waving bending moment and the voltage signal of the swaying bending moment of the wind turbine blade;

The testing unit is used for determining the swing bending moment and the swing bending moment of the wind turbine blade according to the voltage signal of the swing bending moment and the voltage signal of the swing bending moment of the wind turbine blade.

Preferably, the acquisition unit is specifically used for:

Collect the voltage signal of the strain gauge in the swing direction and the voltage signal of the strain gauge in the swing direction inside the wind turbine blade;

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

Further, the test unit is specifically used for:

Determine the flapping moment M _flap and the swaying moment M _edge of the wind turbine blade as follows:

In the formula, U _flap is the voltage signal of the swing bending moment, U _edge is the voltage signal of the swing bending moment, A ₁ is the first calibration coefficient, A ₂ is the second calibration coefficient, A ₃ is the third calibration coefficient, A ₄ is the fourth calibration coefficient, offset _{_flap} is the deflection of the flapping moment, and offset _{_edge} is the deflection of the flutter moment.

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

The present invention provides a method and device for measuring the bending moment of a wind turbine blade taking into account the orthogonal effect, comprising: acquiring the voltage signal of the waving bending moment and the voltage signal of the swaying bending moment of the blade of the wind turbine; The voltage signal of the bending moment and the voltage signal of the sway bending moment determine the swing bending moment and the swing bending moment of the wind turbine blade; the present invention obtains the swing bending moment and the swing bending moment based on the voltage signal of the swing bending moment and the voltage signal of the swing bending moment Vibration and bending moment, taking into account the quadrature sensitive effect between shimmy and swaying, making the test results more accurate and reliable;

Among them, when obtaining the voltage signal of the waving bending moment and the voltage signal of the swaying bending moment of the wind turbine blade, the distance limit between the position of the strain gauge and the position of the flange at the root of the blade is set to avoid the influence of the local stress of the flange on the test results.

Description of drawings

Fig. 1 is a flow chart of a method for measuring the bending moment of a wind turbine blade in consideration of orthogonal influence of the present invention;

FIG. 2 is a schematic diagram of the pasting of the strain gauge in the embodiment of the present invention;

FIG. 3 is a schematic diagram of a wind turbine blade bending moment testing device considering orthogonal effects according to the present invention.

Detailed ways

The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

In order to make the purposes, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments These are some embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

The present invention provides a method for measuring the bending moment of a wind turbine blade considering the orthogonal effect, as shown in FIG. 1 , the method includes:

Obtain the voltage signal of the waving bending moment and the voltage signal of the swaying bending moment of the wind turbine blade;

The swing bending moment and the sway bending moment of the wind turbine blade are determined according to the voltage signal of the swing bending moment and the voltage signal of the swing bending moment of the wind turbine blade.

In order to more clearly demonstrate the purpose of the present invention, the present invention will be further described below with reference to specific embodiments.

In the above embodiment of the present invention, the above-mentioned acquisition of the voltage signal of the swing bending moment and the voltage signal of the sway bending moment of the wind turbine blade includes:

Collect the voltage signal of the strain gauge in the swing direction and the voltage signal of the strain gauge in the swing direction inside the wind turbine blade;

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

Specifically, in the embodiment, as shown in a in Figure 2, the strain gages are preset in the swinging direction and the strain gages are pasted in the swinging direction, and the measured position is realized by using the traditional pasting resistance strain gages to build a Wheatstone bridge. and, as shown in b in Figure 2, the distance L0 between the longitudinal section of the strain gauge 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 For the influence of external environmental factors on the test results, the strain gauge has been treated with moisture-proof.

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

M=slope*U+offset

In the formula, M is the bending moment; U is the voltage signal, slope is the slope, and offset is the deviation;

However, in specific working conditions, the actual strain position may not be in the position of the swaying direction and the swaying direction where the strain gauges are attached, resulting in the swaying bending moment affecting the swaying bending moment, and the swaying bending moment affecting the swaying bending moment, that is, the difference of the orthogonal sensitivity. Therefore, it is necessary to determine the orthogonal sensitivity relationship between the swinging and swaying bending moment signals to correct the bending moment, and the calibration coefficient should satisfy the following formula:

In the formula, A ₁ is the first calibration coefficient, A ₂ is the second calibration coefficient, A ₃ is the third calibration coefficient, A ₄ is the fourth calibration coefficient, U _flap is the voltage signal of the swinging moment, and U _edge is the swing vibration The voltage signal of the bending moment, M _edge and M _flap are the sway and flap bending moments, respectively.

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

Determine the flapping moment M _flap and the swaying moment M _edge of the wind turbine blade as follows:

In the formula, U _flap is the voltage signal of the swing bending moment, U _edge is the voltage signal of the swing bending moment, A ₁ is the first calibration coefficient, A ₂ is the second calibration coefficient, A ₃ is the third calibration coefficient, A ₄ is the fourth calibration coefficient, offset _{_flap} is the deflection of the flapping moment, and offset _{_edge} is the deflection of the flutter moment.

The well-known swing bending moment and sway bending moment also have the following formulas:

In the formula, θ _e is the blade pitch angle, θ _f is the blade rotation azimuth angle, and _MG is the gravitational bending moment of the longitudinal section where the strain gauge is located.

Therefore, in the embodiment of the present invention, the above-mentioned first calibration coefficient A ₁ , second calibration coefficient A ₂ , third calibration coefficient A ₃ , fourth calibration coefficient A ₄ , and swing angle are determined by using a special pitch angle calibration method. The moment deviation offset _{_flap} and the sway bending moment deviation offset _{_edge} , the specific steps are as follows:

1) In a light wind state, fix the blade pitch angle to 0°, and the unit idles for 2-3 turns, then

θ _e = 0°, M _flap = 0, then there are

which can be obtained,

2) Under the condition of light wind, fix the blade pitch angle to 90°, and turn the unit for 2-3 turns

θ _e = 90°, M _edge = 0, then there are

which can be obtained,

3) Under the condition of light wind, fix the blade pitch angle to 45°, and turn the unit for 2-3 turns

则有

和

θ _e = 45°,

then there are

and

和

which can be obtained,

and

4) When the swing bending moment reaches the maximum, there is the following formula:

When the swing moment reaches the minimum, there is the following formula:

Since M _{flap_max} =-M _{flap_min} and M _{edge_max} =-M _{edge_min} , we can get:

Among them, U _{flap_max} is the maximum voltage signal of the flapping moment, U _{flap_min} is the minimum voltage signal of the flapping moment, U _{edge_max} is the maximum voltage signal of the swing bending moment, and U _{edge_min} is the minimum voltage signal of the swing bending moment value, _MG is the gravitational bending moment of the longitudinal section where the strain gauge is located.

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 above-mentioned voltage signal are the average values of more than three times.

Further, the gravitational bending moment M _G of the longitudinal section where the strain gauge is located is determined as follows:

M _G = GL

where G is the gravity 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.

Based on the same inventive concept, the present invention also provides a wind turbine blade bending moment test device that takes into account the orthogonal influence, as shown in FIG. 3 , the device includes:

an acquisition unit, used to acquire the voltage signal of the waving bending moment and the voltage signal of the swaying bending moment of the wind turbine blade;

The testing unit is used for determining the swing bending moment and the swing bending moment of the wind turbine blade according to the voltage signal of the swing bending moment and the voltage signal of the swing bending moment of the wind turbine blade.

Preferably, the acquisition unit is specifically used for:

Collect the voltage signal of the strain gauge in the swing direction and the voltage signal of the strain gauge in the swing direction inside the wind turbine blade;

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

Further, the test unit is specifically used for:

Determine the flapping moment M _flap and the swaying moment M _edge of the wind turbine blade as follows:

In the formula, U _flap is the voltage signal of the swing bending moment, U _edge is the voltage signal of the swing bending moment, A ₁ is the first calibration coefficient, A ₂ is the second calibration coefficient, A ₃ is the third calibration coefficient, A ₄ is the fourth calibration coefficient, offset _{_flap} is the deflection of the flapping moment, and offset _{_edge} is the deflection of the flutter moment.

Further, the distance between the longitudinal section of the strain gauge in the swing direction and the strain gauge in the swing direction and the flange at the root of the wind turbine blade is greater than 0.4D;

Among them, D is the diameter of the cross section of the root of the wind turbine blade.

Further, the first calibration coefficient A ₁ , the second calibration coefficient A ₂ , the third calibration coefficient A ₃ and the fourth calibration coefficient A ₄ are determined as follows:

In the formula, U _{flap_max} is the maximum voltage signal of the flapping moment, U _{flap_min} is the minimum voltage signal of the flapping moment, U _{edge_max} is the maximum voltage signal of the swing bending moment, and U _{edge_min} is the voltage signal of the swing bending moment The minimum value, _MG is the gravitational bending moment of the longitudinal section where the strain gauge is located.

Further, the gravitational bending moment M _G of the longitudinal section where the strain gauge is located is determined as follows:

M _G = GL

where G is the gravity 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.

Further, the flapping moment deviation offset _{_flap} and the sway bending moment deviation offset _{_edge} are determined as follows:

In the formula, U _{flap_max} is the maximum voltage signal of the flapping moment, U _{flap_min} is the minimum voltage signal of the flapping moment, U _{edge_max} is the maximum voltage signal of the swing bending moment, and U _{edge_min} is the voltage signal of the swing bending moment minimum value.

To sum up, the present invention provides a method and device for measuring the bending moment of a wind turbine blade taking into account the orthogonal effect, including: acquiring the voltage signal of the waving bending moment and the voltage signal of the swaying bending moment of the blade of the wind turbine; The voltage signal of the swinging bending moment and the voltage signal of the swaying bending moment of the wind turbine blade determine the swinging bending moment and the swinging bending moment of the wind turbine blade; the present invention is based on the voltage signal of the swinging bending moment and the voltage signal of the swinging bending moment to obtain The swing bending moment and the sway bending moment take into account the orthogonal sensitive influence between the swing and swing, making the test results more accurate and reliable;

Among them, when obtaining the voltage signal of the waving bending moment and the voltage signal of the swaying bending moment of the wind turbine blade, the distance limit between the position of the strain gauge and the position of the flange at the root of the blade is set to avoid the influence of the local stress of the flange on the test results.

As will be appreciated by those skilled in the art, the embodiments of the present application may be provided as a method, a system, or a computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) having computer-usable program code embodied therein.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the present application. It will be understood that each flow and/or block in the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to the processor of a general purpose computer, special purpose computer, embedded processor or other programmable data processing device to produce a machine such that the instructions executed by the processor of the computer or other programmable data processing device produce Means for implementing the functions specified in a flow or flow of a flowchart and/or a block or blocks of a block diagram.

These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory result in an article of manufacture comprising instruction means, the instructions The apparatus implements the functions specified in the flow or flow of the flowcharts and/or the block or blocks of the block diagrams.

These computer program instructions can also be loaded on a computer or other programmable data processing device to cause a series of operational steps to be performed on the computer or other programmable device to produce a computer-implemented process such that The instructions provide steps for implementing the functions specified in the flow or blocks of the flowcharts and/or the block or blocks of the block diagrams.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: the present invention can still be Modifications or equivalent replacements are made to the specific embodiments of the present invention, and any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention shall be included within the protection scope of the claims of the present invention.

Claims (10)

1. a wind turbine blade bending moment test method taking into account orthogonal influence, is characterized in that, described method comprises: Obtain the voltage signal of the waving bending moment and the voltage signal of the swaying bending moment of the wind turbine blade; The swing bending moment and the sway bending moment of the wind turbine blade are determined according to the voltage signal of the swing bending moment and the voltage signal of the swing bending moment of the wind turbine blade. 2. The method according to claim 1, wherein the acquiring the voltage signal of the swing bending moment and the voltage signal of the sway bending moment of the blades of the wind turbine comprises: Collect the voltage signal of the strain gauge in the swing direction and the voltage signal of the strain gauge in the swing direction inside the wind turbine blade; The voltage signal of the strain gauge in the swing direction and the voltage signal of the strain gauge in the swing direction are isolated and amplified respectively to obtain the voltage signal of the swing bending moment and the voltage signal of the swing bending moment of the wind turbine blade. 3. The method according to claim 2, wherein the distance between the longitudinal section where the strain gauge in the swinging direction and the strain gauge in the swinging direction are located and the flange at the root of the wind turbine blade is greater than 0.4D; Among them, D is the diameter of the cross section of the root of the wind turbine blade. 4 . The method according to claim 3 , wherein the swing bending moment and the swing bending moment of the wind turbine blade are determined according to the voltage signal of the swing bending moment and the voltage signal of the swing bending moment of the wind turbine blade. 5 . ,include: Determine the flapping moment M _flap and the swaying moment M _edge of the wind turbine blade as follows:

In the formula, U _flap is the voltage signal of the swing bending moment, U _edge is the voltage signal of the swing bending moment, A ₁ is the first calibration coefficient, A ₂ is the second calibration coefficient, A ₃ is the third calibration coefficient, A ₄ is the fourth calibration coefficient, offset _{_flap} is the deflection of the flapping moment, and offset _{_edge} is the deflection of the flutter moment. 5. The method of claim 4, wherein the first calibration coefficient A ₁ , the second calibration coefficient A ₂ , the third calibration coefficient A ₃ and the fourth calibration coefficient A ₄ are determined as follows:

In the formula, U _{flap_max} is the maximum voltage signal of the flapping moment, U _{flap_min} is the minimum voltage signal of the flapping moment, U _{edge_max} is the maximum voltage signal of the swing bending moment, and U _{edge_min} is the voltage signal of the swing bending moment The minimum value, _MG is the gravitational bending moment of the longitudinal section where the strain gauge is located. 6. The method according to claim 5, wherein the gravitational bending moment M _G of the longitudinal section where the strain gauge is located is determined as follows: M _G = GL where G is the gravity 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. 7. The method of claim 4, wherein the flapping moment deviation _{offset_flap} and the flutter bending moment deviation _{offset_edge} are determined as follows:

In the formula, U _{flap_max} is the maximum voltage signal of the flapping moment, U _{flap_min} is the minimum voltage signal of the flapping moment, U _{edge_max} is the maximum voltage signal of the swing bending moment, and U _{edge_min} is the voltage signal of the swing bending moment minimum value. 8. A wind turbine blade bending moment testing device considering orthogonal influence, wherein the device comprises: an acquisition unit, used to acquire the voltage signal of the waving bending moment and the voltage signal of the swaying bending moment of the wind turbine blade; The testing unit is used for determining the swing bending moment and the swing bending moment of the wind turbine blade according to the voltage signal of the swing bending moment and the voltage signal of the swing bending moment of the wind turbine blade. 9. The apparatus according to claim 8, wherein the acquiring unit is specifically configured to: Collect the voltage signal of the strain gauge in the swing direction and the voltage signal of the strain gauge in the swing direction inside the wind turbine blade; The voltage signal of the strain gauge in the swing direction and the voltage signal of the strain gauge in the swing direction are isolated and amplified respectively to obtain the voltage signal of the swing bending moment and the voltage signal of the swing bending moment of the wind turbine blade. 10. The device according to claim 9, wherein the test unit is specifically used for: Determine the flapping moment M _flap and the swaying moment M _edge of the wind turbine blade as follows:

In the formula, U _flap is the voltage signal of the swing bending moment, U _edge is the voltage signal of the swing bending moment, A ₁ is the first calibration coefficient, A ₂ is the second calibration coefficient, A ₃ is the third calibration coefficient, A ₄ is the fourth calibration coefficient, offset _{_flap} is the deflection of the flapping moment, and offset _{_edge} is the deflection of the flutter moment.

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