Wind turbine generator blade clearance control system and method

Abstract

The embodiment of the invention provides a wind turbine generator blade clearance control system and method. The system comprises a strain measurement module which comprises a plurality of optical fiber strain sensors arranged on the inner surface of a wind turbine generator blade at intervals and is used for measuring the strain of the blade; the distance calculation module is used for calculating a predicted distance between the tip of the blade and the tower according to the strain of the blade, the current azimuth angle of the blade, the rotating speed of a wind wheel, the wind speed, the static distance between the tip of the blade and the tower, the length of the blade and the pitch angle of a cabin; the interference judgment module is used for judging whether the blade and the tower drum have interference risks or not according to the predicted distance; and the variable pitch control module is used for carrying out independent variable pitch control adjustment on the pitch angle of the blade when the interference risk exists between the blade and the tower drum. The embodiment of the invention is not influenced by environmental factors, and has the capability of protecting the blades from interference with the tower drum in all-weather operation; the independent variable pitch is used for achieving blade clearance protection control, and the generating capacity loss can be effectively reduced.

Description

Technical Field

[0001] Embodiments of the present disclosure belong to the technical field of wind turbine blade clearance control, and particularly relate to a wind turbine blade clearance control system and method. Background Art

[0002] The blades of large megawatt wind turbines can reach or even exceed 100 meters in length. Only the root part is fixed on the hub, and the overall structure is similar to a cantilever beam. During the power generation operation of the unit, due to the action of wind force, the blade will generate large deformations at the tip after being stressed. In some extreme working conditions, the deformation at the blade tip is extremely large, and there is a situation where the blade interferes with the tower during the rotation of the wind turbine, affecting the safety of the unit. In the lightest case, the blade breaks, and in the worst case, the unit collapses and is completely damaged. In order to reduce the safety risks during the power generation operation of the unit, the monitoring and control of the blade tip deformation have become the key technologies for large megawatt wind turbines, which is called blade clearance control.

[0003] The existing blade clearance control adopts methods such as video monitoring and lidar monitoring, and controls by measuring the distance between the blade tip and the tower in real time to prevent the blade from interfering with the tower during the power generation operation of the unit.

[0004] However, video or lidar is easily affected by environmental factors and cannot effectively monitor blade deformation in some extreme cases, making it difficult to control the reduction of blade-tower interference. Moreover, the existing clearance control methods are relatively simple, mainly by using centralized pitch control to greatly increase the blade pitch angle or directly shutting down the machine, resulting in a large loss of power generation. Summary of the Invention

[0005] Embodiments of the present disclosure aim to at least solve one of the technical problems existing in the prior art, and provide a wind turbine blade clearance control system and method.

[0006] One aspect of the present disclosure provides a wind turbine blade clearance control system, which includes:

[0007] A strain measurement module, including a plurality of fiber optic strain sensors arranged at intervals on the inner surface of the wind turbine blade, for measuring the strain of the blade;

[0008] A distance calculation module, for calculating the predicted distance between the blade tip and the tower according to the strain of the blade, the current blade azimuth angle, the wind turbine speed, the wind speed, the static distance between the blade tip and the tower, the blade length, and the nacelle pitch angle;

[0009] An interference judgment module, for judging whether there is an interference risk between the blade and the tower according to the predicted distance;

[0010] The pitch control module is used to perform independent pitch control adjustment on the pitch angle of the blade when there is a risk of interference between the blade and the tower barrel.

[0011] Further, each of the fiber optic strain sensors is correspondingly arranged on each measurement section radially divided from the blade tip to the root.

[0012] Further, the distance calculation module is specifically used for:

[0013] Adding the strains of the blade at each measurement section to calculate the current deformation amount at the blade tip;

[0014] Obtaining the predicted blade azimuth angle based on the current blade azimuth angle and the wind turbine rotor speed;

[0015] Obtaining the deformation offset amount based on the current deformation amount at the blade tip, the current blade azimuth angle, and the wind speed;

[0016] Obtaining the predicted distance between the blade tip and the tower barrel based on the current deformation amount at the blade tip, the deformation offset amount, the static distance between the blade tip and the tower barrel, the blade length, and the nacelle pitch angle.

[0017] Optionally, the interference judgment module is specifically used for:

[0018] Setting a minimum distance threshold between the blade tip and the tower barrel;

[0019] Comparing the predicted distance with the minimum distance threshold, and when the predicted distance is less than the minimum distance threshold, determining that there is a risk of interference between the blade and the tower barrel.

[0020] Further, the pitch control module is specifically used for:

[0021] Setting the target pitch angle of the blade;

[0022] Performing independent pitch control adjustment on the pitch angle of the blade according to the target pitch angle.

[0023] Further, the target pitch angle is the sum of the blade centralized control pitch angle and the interference avoidance pitch angle.

[0024] On the other hand, the present disclosure provides a method for controlling the clearance of a wind turbine blade, and the method includes:

[0025] Correspondingly and at intervals, arranging a plurality of fiber optic strain sensors on a plurality of measurement sections radially divided from the inner surface of the wind turbine blade from the blade tip to the root for measuring the strain of the blade;

[0026] Calculating the predicted distance between the blade tip and the tower barrel based on the strain of the blade, the current blade azimuth angle, the wind turbine rotor speed, the wind speed, the static distance between the blade tip and the tower barrel, the blade length, and the nacelle pitch angle;

[0027] Judge whether there is an interference risk between the blade and the tower according to the predicted distance;

[0028] When there is an interference risk between the blade and the tower, perform independent pitch control adjustment on the pitch angle of the blade.

[0029] Further, calculating the predicted distance between the blade tip and the tower according to the strain of the blade, the current blade azimuth angle, the wind turbine rotor speed, the wind speed, the static distance between the blade tip and the tower, the blade length, and the nacelle pitch angle includes:

[0030] Add the strains of the blades at each measurement section to calculate the deformation amount of the current blade tip;

[0031] Obtain the predicted blade azimuth angle according to the current blade azimuth angle and the wind turbine rotor speed;

[0032] Obtain the deformation offset according to the deformation amount of the current blade tip, the current blade azimuth angle, and the wind speed;

[0033] Obtain the predicted distance between the blade tip and the tower according to the deformation amount of the current blade tip, the deformation offset, the static distance between the blade tip and the tower, the blade length, and the nacelle pitch angle.

[0034] Further, judging whether there is an interference risk between the blade and the tower according to the predicted distance includes:

[0035] Set the minimum distance threshold between the blade tip and the tower;

[0036] Compare the predicted distance with the minimum distance threshold. When the predicted distance is less than the minimum distance threshold, it is judged that there is an interference risk between the blade and the tower.

[0037] Further, controlling and adjusting the pitch angle of the blade includes:

[0038] Set the target pitch angle of the blade; wherein, the target pitch angle is the sum of the blade centralized control pitch angle and the interference avoidance pitch angle;

[0039] Perform independent pitch control adjustment on the pitch angle of the blade according to the target pitch angle.

[0040] A blade clearance control system and method for a wind turbine according to an embodiment of the present disclosure are not affected by environmental factors and can operate all-weather. Especially under extreme weather conditions, it still has the ability to protect the blade and the tower from interference; using independent pitch to achieve blade clearance protection control can effectively reduce the power generation loss compared with shutting down or centrally raising the blade pitch angle. Description of the Drawings

[0041] Figure 1 Structural schematic diagram of a blade clearance control system for a wind turbine according to an embodiment of the present disclosure;

[0042] Figure 2 Schematic diagram of the expected distance between the blade tip and the tower according to another embodiment of the present disclosure;

[0043] Figure 3 Flow schematic diagram of a blade clearance control method for a wind turbine according to another embodiment of the present disclosure. Detailed implementation manners

[0044] Next, the technical solutions in the embodiments of the present disclosure will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present disclosure.

[0045] In addition, the described features, structures or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, many specific details are provided to give a full understanding of the embodiments of the present disclosure. However, those skilled in the art will realize that the technical solutions of the present disclosure may be practiced without one or more of the specific details, or other methods, components, devices, steps, etc. may be adopted. In other cases, well-known methods, devices, implementations or operations are not shown or described in detail to avoid obscuring various aspects of the present disclosure.

[0046] The flowcharts shown in the accompanying drawings are only illustrative and do not necessarily include all the content and operations / steps, nor are they necessarily executed in the described order. For example, some operations / steps may be decomposed, and some operations / steps may be combined or partially combined. Therefore, the actual execution order may be changed according to the actual situation.

[0047] It should be understood that although terms such as first, second, and third may be used in the present disclosure to describe various components, these components should not be limited by these terms. These terms are used to distinguish one component from another. Therefore, the first component described below may be referred to as the second component without departing from the teachings of the concept of the present disclosure. As used in the present disclosure, the term "and / or" includes any one of the associated listed items and all combinations of one or more of them.

[0048] Those skilled in the art can understand that the accompanying drawings are only schematic diagrams of exemplary embodiments, and the modules or processes in the accompanying drawings are not necessarily essential for implementing the present disclosure, and therefore cannot be used to limit the protection scope of the present disclosure.

[0049] Such as Figure 1As shown in the figure, an embodiment of the present disclosure provides a clearance control system for a wind turbine blade. The system includes:

[0050] A strain measurement module 110, including a plurality of fiber optic strain sensors spaced on the inner surface of the wind turbine blade, for measuring the strain of the blade;

[0051] A distance calculation module 120, for calculating the predicted distance between the blade tip and the tower according to the strain of the blade, the current blade azimuth angle, the wind turbine rotor speed, the wind speed, the static distance between the blade tip and the tower, the blade length, and the nacelle pitch angle;

[0052] An interference judgment module 130, for judging whether there is an interference risk between the blade and the tower according to the predicted distance;

[0053] A pitch control module 140, for controlling and adjusting the pitch angle of the blade when there is an interference risk between the blade and the tower.

[0054] Specifically, a fiber optic strain measurement device, that is, the strain measurement module 110, is installed on the inner surface of the wind turbine blade. N measurement sections are radially divided on the blade from the tip to the root to ensure that the blade deformation between two measurement section intervals is approximately linearly variable. The strain measurement module 110 includes a plurality of fiber optic strain sensors, which are respectively installed on each measurement section to form monitoring points arranged at intervals along the radial direction from the blade root to the blade tip, and measure the strain Δε of the blade at the i-th section x,i 、Δε y,i 、Δε z,i , where x, y, and z respectively represent the three directions of the three-dimensional coordinate system. The fiber optic strain sensor can also be replaced by a strain gauge. Let the distance between each section of the blade be L i , and the deformation generated within the section distance is:

[0055]

[0056] where, ΔL i represents the length of the measurement point at the i-th section. The strain transmission device is installed on the hub and transmits the strain signals of each monitoring point in the blade to the controller located in the nacelle through slip rings or wireless communication.

[0057] The distance calculation module 120 acquires the current blade azimuth angle the wind turbine rotor speed ω, the wind speed v, the nacelle pitch angle θ, and the strain signals ε of each monitoring point from the above-mentioned controller or the control system of the wind turbine j,i . Add the strains ε of the blade at each of the measurement sections j,i to calculate the current blade tip deformation j = x, y, z. According to the current blade azimuth angle Knowing the current position of the blade, and then calculating the azimuth angle of the blade after a time period t based on the rotational speed ω of the wind turbine rotor, that is, the predicted azimuth angle of the blade when it rotates to the position of the tower barrel When the blade is within the range of the tower shadow effect, a deformation offset needs to be added to the deformation of the blade tip where v represents the measured value of the current wind speed, and the deformation offset is a function related to the wind speed v and the predicted azimuth angle of the blade The deformation of the blade tip ε j Based on this, the predicted deformation amount ε of the blade tip after a time period t is obtained e = ε x + ε s where ε x is the current deformation amount of the blade tip in the x direction ε j When the wind turbine is in the shutdown and stationary state, the minimum distance between the blade tip and the tower barrel is L s The blade length is R, and the pitch angle of the nacelle relative to the tower barrel during power generation operation is θ. Considering multiple factors such as the above-mentioned blade tip deformation, tower shadow effect, and nacelle pitch, the predicted distance between the blade tip and the tower barrel after a time period t is finally obtained as L tip = L s + Rsinθ - ε e . As Figure 2 shown, where 21 is the blade position under the nacelle pitch, 22 is the blade position in the shutdown and stationary state, 23 is the predicted deformation position of the blade, and 24 is the tower barrel position

[0058] The interference judgment module 130 sets a suitable minimum distance threshold L between the blade tip and the tower barrel min , when the predicted distance L between the blade tip and the tower barrel tip is less than the minimum distance threshold L min , it is determined that there is an interference risk between the blade and the tower barrel

[0059] When it is determined that there is an interference risk between the blade and the tower barrel, the pitch control module 140 sets a target pitch angle of the blade β = β c + β tip , where β c is the pitch angle of the centralized control of all blades of the wind turbine, and β tip is the pitch angle adjustment amount to avoid interference between the blade and the tower barrel. Subsequently, the pitch angle of the blade is independently adjusted by pitch control according to this target pitch angle, so as to avoid interference between the blade and the tower barrel

[0060] A wind turbine blade clearance control system according to an embodiment of the present disclosure is not affected by environmental factors and can achieve all-weather operation, especially in extreme weather conditions, and still has the ability to protect the blades from interference with the tower; independent variable pitch is used to achieve blade clearance protection control, which can effectively reduce power generation loss compared to shutdown or centralized lifting of the blade pitch angle.

[0061] like Figure 3 As shown, another embodiment of the present disclosure provides a method for controlling blade clearance of a wind turbine, the method comprising:

[0062] Step S1: a plurality of optical fiber strain sensors are arranged at corresponding intervals on a plurality of measurement sections radially divided from the blade tip to the root on the inner surface of a wind turbine blade to measure the strain of the blade.

[0063] Specifically, N measurement sections are radially divided from the tip to the root of the blade to ensure that the blade deformation between two measurement sections varies approximately linearly. Multiple optical fiber strain sensors are installed on each measurement section, forming monitoring points arranged radially from the root to the tip of the blade, and the strain Δε of the blade at the i-th section is measured. x,i , Δε y,i , Δε z,i , where x, y, and z represent the three directions of the three-dimensional coordinate system. The optical fiber strain sensor can also be replaced by a strain gauge. Assume that the spacing of each section of the blade is L i , the deformation generated within the cross-sectional spacing is:

[0064]

[0065] Where, ΔL i The strain transmitter is mounted on the hub and transmits the strain signals of each monitoring point in the blade to the controller in the nacelle via slip rings or wireless communication.

[0066] Step S2: Calculate the estimated distance between the blade tip and the tower based on the strain of the blade, the current blade azimuth, the rotor speed, the wind speed, the static distance between the blade tip and the tower, the blade length, and the nacelle pitch angle.

[0067] Specifically, the current blade azimuth angle is collected from the controller or the control system of the wind turbine. Wind rotor speed ω, wind speed v, nacelle pitch angle θ and strain signal ε of each monitoring point j,i The blade strain ε of each measurement section is j,i Add and calculate to get the current blade tip deformation j=x,y,z. According to the current blade azimuth Knowing the current position of the blade, the azimuth angle of the blade after a time t is calculated according to the rotational speed ω of the wind turbine rotor, that is, the predicted azimuth angle of the blade when it rotates to the position of the tower barrel. When the blade is within the range of the tower shadow effect, a deformation offset needs to be added to the deformation of the blade tip. Where v represents the measured value of the current wind speed, and the deformation offset is a function related to the wind speed v and the predicted azimuth angle of the blade. The deformation of the blade tip ε j The predicted deformation amount ε of the blade tip after a time t is obtained. e = ε x + ε s Where ε x Is the current deformation amount ε of the blade tip in the x direction. j When the wind turbine is in a stationary state, the minimum distance between the blade tip and the tower barrel is L. s The length of the blade is R, and the pitch angle of the nacelle relative to the tower barrel during power generation operation is θ. Considering multiple factors such as the above-mentioned blade tip deformation, tower shadow effect, and nacelle pitch, the predicted distance between the blade tip and the tower barrel after a time t is finally obtained as L. tip = L s + Rsinθ - ε e . As Figure 2 Shown, where 21 is the blade position under nacelle pitch, 22 is the blade position in the stationary state, 23 is the predicted deformation position of the blade, and 24 is the tower barrel position.

[0068] Step S3: Judge whether there is an interference risk between the blade and the tower barrel according to the predicted distance.

[0069] Specifically, a suitable minimum distance threshold L between the blade tip and the tower barrel is set. min When the predicted distance L between the blade tip and the tower barrel tip Is less than the minimum distance threshold L min , it is determined that there is an interference risk between the blade and the tower barrel.

[0070] Step S4: When there is an interference risk between the blade and the tower barrel, perform independent pitch control adjustment on the pitch angle of the blade.

[0071] Specifically, when it is determined that there is an interference risk between the blade and the tower barrel, the pitch control module 140 sets a target pitch angle β of the blade = β c + β tip , where β c Is the pitch angle of the centralized control of all blades of the wind turbine, and β tip Is the pitch angle adjustment amount to avoid interference between the blade and the tower barrel. Subsequently, the pitch angle of the blade is adjusted by independent pitch control according to this target pitch angle, so as to avoid interference between the blade and the tower barrel.

[0072] A blade clearance control method for a wind turbine according to an embodiment of the present disclosure is not affected by environmental factors and can operate all-weather. In particular, it still has the ability to protect the blades and the tower from interference under extreme weather conditions. Using independent pitch to achieve blade clearance protection control can effectively reduce power generation loss compared to shutting down or collectively raising the blade pitch angle.

[0073] It can be understood that the above embodiments are merely exemplary embodiments adopted to illustrate the principles of the present disclosure. However, the present disclosure is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present disclosure, and these modifications and improvements are also regarded as the protection scope of the present disclosure.

Claims

1. A blade clearance control system for a wind turbine, characterized in that, The system includes: a strain measurement module, including a plurality of fiber optic strain sensors spaced on the inner surface of the wind turbine blade, for measuring the strain of the blade; a distance calculation module, for calculating the predicted distance between the blade tip and the tower according to the strain of the blade, the current blade azimuth angle, the wind turbine rotor speed, the wind speed, the static distance between the blade tip and the tower, the blade length, and the nacelle pitch angle; an interference judgment module, for judging whether there is an interference risk between the blade and the tower according to the predicted distance; a pitch control module, for independently controlling and adjusting the pitch angle of the blade when there is an interference risk between the blade and the tower.

2. The system according to claim 1, wherein Each of the fiber optic strain sensors is correspondingly arranged on each measurement section radially divided from the blade tip to the root of the blade.

3. The system according to claim 2, wherein The distance calculation module is specifically used for: adding the strains of the blade at each of the measurement sections to calculate the current deformation amount of the blade tip; obtaining the predicted blade azimuth angle according to the current blade azimuth angle and the wind turbine rotor speed; obtaining the deformation offset amount according to the current deformation amount of the blade tip, the current blade azimuth angle, and the wind speed; obtaining the predicted distance between the blade tip and the tower according to the current deformation amount of the blade tip, the deformation offset amount, the static distance between the blade tip and the tower, the blade length, and the nacelle pitch angle.

4. The system according to claim 1, characterized in that, The interference judgment module is specifically used for: setting a minimum distance threshold between the blade tip and the tower; comparing the predicted distance with the minimum distance threshold, and when the predicted distance is less than the minimum distance threshold, judging that there is an interference risk between the blade and the tower.

5. The system according to any one of claims 1 to 4, characterized in that, The pitch control module is specifically used for: setting the target pitch angle of the blade; independently controlling and adjusting the pitch angle of the blade according to the target pitch angle.

6. The system according to claim 5, characterized in that, The target pitch angle is the sum of the blade centralized control pitch angle and the interference avoidance pitch angle.

7. A method for controlling the clearance of a wind turbine blade, characterized in that, The method includes: correspondingly and spacedly arranging a plurality of fiber optic strain sensors on a plurality of measurement sections radially divided from the blade tip to the root of the inner surface of the wind turbine blade, for measuring the strain of the blade; calculating the predicted distance between the blade tip and the tower according to the strain of the blade, the current blade azimuth angle, the wind turbine rotor speed, the wind speed, the static distance between the blade tip and the tower, the blade length, and the nacelle pitch angle; judging whether there is an interference risk between the blade and the tower according to the predicted distance; independently controlling and adjusting the pitch angle of the blade when there is an interference risk between the blade and the tower.

8. The method according to claim 7, characterized in that, The calculating the predicted distance between the blade tip and the tower according to the strain of the blade, the current blade azimuth angle, the wind turbine rotor speed, the wind speed, the static distance between the blade tip and the tower, the blade length, and the nacelle pitch angle includes: adding the strains of the blade at each of the measurement sections to calculate the current deformation amount of the blade tip; obtaining the predicted blade azimuth angle according to the current blade azimuth angle and the wind turbine rotor speed; obtaining the deformation offset amount according to the current deformation amount of the blade tip, the current blade azimuth angle, and the wind speed; obtaining the predicted distance between the blade tip and the tower according to the current deformation amount of the blade tip, the deformation offset amount, the static distance between the blade tip and the tower, the blade length, and the nacelle pitch angle.

9. The method according to claim 7, wherein Judging whether there is an interference risk between the blade and the tower according to the predicted distance includes: Setting a minimum distance threshold between the tip of the blade and the tower; Comparing the predicted distance with the minimum distance threshold, and when the predicted distance is less than the minimum distance threshold, it is judged that there is an interference risk between the blade and the tower.

10. The method according to any one of claims 7 to 9, characterized in that, Controlling and adjusting the pitch angle of the blade includes: Setting the target pitch angle of the blade; wherein, the target pitch angle is the sum of the centralized control pitch angle of the blade and the interference avoidance pitch angle; Independently controlling and adjusting the pitch angle of the blade according to the target pitch angle.

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