A wind turbine blade damage monitoring device and monitoring method

Abstract

The present invention discloses a blade damage monitoring device, comprising at least three groups of audio acquisition processors for collecting blade audio signals; the present invention adopts a multi-channel three-dimensional audio acquisition processor installation structure, which can more comprehensively collect the audio signals generated by the wind turbine blades sweeping across the sky in a complex environment, even when the orientation of the wind turbine cabin is constantly changing. At the same time, under the multi-channel triangular installation architecture, the interference of environmental noise and Doppler effect can be reduced in the audio data collected at different orientations and heights. The present invention also discloses a blade damage monitoring method, which can realize online monitoring. In the monitoring method of the present invention, the audio time domain signal is converted into an audio frequency domain signal, and then reversed to obtain the real audio frequency domain signal after eliminating the Doppler effect at three observation points, which can provide feedback on the authenticity of the audio data generated by the wind turbine blade passing the lowest point.

Description

Technical Field

[0001] The present invention relates to the field of wind turbine blade monitoring, and in particular to a wind turbine blade damage monitoring device and a monitoring method. Background Art

[0002] Since most wind turbines are installed in areas with harsh environments, they are prone to failure. If there is no timely warning of the failure, it will not only affect the life and working efficiency of the equipment, but may even lead to major accidents such as damage to the wind turbine, causing irreparable losses. The wind turbine blades are the most important structure of the wind turbine. For large wind turbines, the safety of the wind turbine blades is usually directly related to the power generation efficiency of the entire wind turbine generator set. Therefore, ensuring the safety of the wind turbine blades has become the highest level of concern. At present, it is necessary to conduct real-time and accurate online monitoring of the blade operating status to effectively ensure the safe operation of the wind turbine blades.

[0003] In the existing technology, the following two methods are usually used to safely monitor the operating status of wind turbine blades: 1. UAV blade tip imaging method: When the wind turbine blades are locked, a drone is used to capture and image the blades under a set route. The captured image group is then subjected to image recognition to obtain high-definition images of the damaged blades, thereby determining the damage condition of the blades; 2. Three-dimensional thermal image analysis method: Through a detection device, the thermal imaging equipment is synchronized with the wind turbine blades, and the thermal imaging data of the blades is collected by an infrared imager. An infrared three-dimensional thermal image of the blades is constructed to analyze and judge the damage condition of the blades.

[0004] The problems with the above monitoring methods are: the first method uses drone image shooting. Under this solution, the wind turbine needs to be shut down and the blades locked before it can work normally. At the same time, manpower is required to operate the drone, which increases the manpower cost of monitoring. At the same time, it is impossible to perform real-time monitoring without affecting the normal operation of the wind turbine; the second method, three-dimensional thermal image analysis, has complex monitoring equipment, difficult operation, and high cost, and still cannot solve the problem of real-time online monitoring.

[0005] In summary, there is an urgent need for a wind turbine blade damage monitoring device and a monitoring method to solve the problem of how to accurately monitor wind turbine damage in real time in the prior art. Summary of the Invention

[0006] The present invention aims to provide a wind turbine blade damage monitoring device and method to solve the problem of how to accurately monitor wind turbine damage in real time in the prior art. The specific technical solution is as follows:

[0007] A wind turbine blade damage monitoring device includes at least three groups of audio acquisition processors for collecting blade audio signals;

[0008] Multiple groups of audio acquisition processors are arranged along the circumference of the wind turbine tower and are not in the same horizontal plane; three groups of audio acquisition processors are all connected to an external solution system.

[0009] Preferably, in the above technical solution, among the at least three groups of audio acquisition processors, the first group of audio acquisition processors is arranged on the wind turbine tower, and the second group of audio acquisition processors and the third group of audio acquisition processors are both arranged on the ground.

[0010] In the above technical solution, preferably, the lines connecting the projection points of the three groups of audio acquisition processors in the horizontal plane form an equilateral triangle; and the first group of audio acquisition processors is arranged at the same height as the lowest point of the blade.

[0011] A method for monitoring fan blade damage, using the fan blade damage monitoring device, comprises the following steps:

[0012] Step S1: Establish a three-dimensional coordinate system with the geometric center of the wind turbine base as the origin O, the east direction as the X axis, the north direction as the Y axis, and the vertical ground as the Z axis;

[0013] Step S2: Obtain the coordinates of the lowest point of the fan blade at time t0 and after time t; obtain the linear velocity v of the lowest point of the fan blade from time t0 to time t m ;

[0014] Step S3: Get v m In C i and P t The component v″ on the connecting line, C i Indicates the location of an audio acquisition processor i; P t Indicates the coordinate point of the lowest point of the fan blade after time t;

[0015] Step S4: Obtain the sound wave frequency f′ at the lowest point of the blade observed by the position where the audio acquisition processor i is located through the component v″ Ci Let f′ Ci The audio time domain signal is P′ Ci , P′ Ci Converted into the original audio frequency domain signal F(P′ Ci ); F(P′ Ci ) is inversely deduced to obtain the real audio frequency domain signal F(P Ci );

[0016] Step S5: Through F(P Ci ) is compared with the audio frequency domain eigenvalues ​​of a normal and undamaged blade to determine whether the blade is abnormal or damaged.

[0017] The above technical solution is preferably, wherein step S2 includes: step S2.1:

[0018] The coordinate point of the lowest point of the fan blade at time t0 is P0 = (R Y sinθ0,R Y cosθ0,H,θ0);

[0019] After time t, the coordinate point P of the lowest point of the fan blade t =(R Y sinθ t , R Y cosθ t ,H,θ t );

[0020] Among them, R Y represents the radius of rotation of the lowest point of the wind turbine blade along the center of the tower base; θ0 is the angle between the line connecting the lowest point of the wind turbine blade and the origin O at time t0 and the X-axis; θ t is the angle between the projection of the line connecting the lowest point of the fan blade and the origin O on the XOY plane and the X-axis after time t; H is the height of the lowest point of the fan blade from the ground;

[0021] Step S2.2: Linear velocity v m As shown in formula 1):

[0022] v m =ωR Y 1);

[0023] Where ω represents the angular velocity of the fan blades.

[0024] The above technical solution is preferred, in step S3, v″ is obtained as follows:

[0025] Step S3.1: Get the linear velocity v m In C i and P′ t The component v' on the connecting line; where P' t Indicates P t Projection point on the horizontal plane;

[0026] Step S3.2: Solve for the component v′ in C i and P t The component v″ on the connecting line.

[0027] The above technical solution is preferably, in step S3.1, v′ is obtained as shown in formula 2):

[0028]

[0029] Among them, R J Indicates the tower radius; η i In the counterclockwise direction, C iThe angle between the projection of the line connecting the origin O on the base plane and the positive X axis.

[0030] The above technical solution is preferred, in step S3.2, v″ is obtained as shown in formula 3):

[0031]

[0032] Among them, R J represents the radius of the tower; η i In the counterclockwise direction, C i The angle between the projection of the line connecting the origin O on the base plane and the positive X axis; i Indicates C i Coordinate value on the X axis; y i Indicates C i The coordinate value on the Y axis; Z i Indicates C i The coordinate value on the Z axis.

[0033] The above technical solution is preferred, wherein step S4 includes:

[0034] Step S4.1: Obtain the sound wave frequency f′ Ci , as shown in formula 4):

[0035]

[0036] Among them, u is the speed of sound waves; f represents the actual frequency of sound waves generated during propagation;

[0037] Step S4.2: Let f′ Ci The audio time domain signal is P′ Ci , through Fourier transform, the audio time domain signal P′ Ci Converted into the original audio frequency domain signal F(P′ Ci ), where F represents Fourier transform operation;

[0038] Step S4.3: Use formula 4) to convert the initial audio frequency domain signal F(P′) Ci ) is inversely deduced to obtain the real audio frequency domain signal F(P Ci ).

[0039] The above technical solution is preferred, wherein step S5 includes:

[0040] Step S5.1: Calculate the average value of the real audio frequency domain signals observed by the three groups of audio acquisition processors to obtain the precise audio frequency domain data F(P) observed at the lowest point of the blade at different three-dimensional positions, as shown in Equation 5):

[0041] F(P)=AVERAGE(F(P C1 ), F(PC2 ), F(P C3 )) 5);

[0042] Step S5.2: Compare the precise audio frequency domain data F(P) with the audio frequency domain characteristic values ​​of a normal, undamaged blade to determine whether the blade is abnormal or damaged;

[0043] Among them, AVERAGE represents the average value operation; F(P C1 ) represents the real audio frequency domain signal observed by the first group of audio acquisition processors; F(P C2 ) represents the real audio frequency domain signal observed by the second group of audio acquisition processors; F(P C3 ) represents the real audio frequency domain signal observed by the third group of audio acquisition processors.

[0044] The application of the technical solution of the present invention has the following beneficial effects:

[0045] (1) The blade damage monitoring device of the present invention includes at least three groups of audio acquisition processors for collecting blade audio signals; multiple groups of audio acquisition processors are arranged along the circumference of the wind turbine tower; the three groups of audio acquisition processors are not in the same horizontal plane; in the monitoring device of the present invention, a multi-channel three-dimensional audio acquisition processor installation structure is adopted, even when the orientation of the wind turbine cabin is constantly changing, it is possible to more comprehensively collect the audio signals generated by the wind turbine blades sweeping across the sky in a complex environment; at the same time, under the multi-channel triangular installation architecture, the interference of environmental noise and Doppler effect can be reduced in the audio data collected at different directions and heights.

[0046] (2) The blade damage monitoring method of the present invention determines whether the blade is abnormal or damaged by calculating the real audio frequency domain signal and comparing it with the audio frequency domain characteristic value of the undamaged blade. It can realize online monitoring and avoid a series of problems caused by the use of drone blade tip image shooting method or three-dimensional thermal image analysis method. In addition, after Fourier transform, the audio time domain signal is converted into an audio frequency domain signal, and then reversely deduced to obtain the real audio frequency domain signal after eliminating the Doppler effect at the three observation points (i.e., the location points where the three groups of audio acquisition processors are located). This can make the monitored audio data more comprehensive and accurate in feeding back the authenticity of the audio data generated when the wind turbine blade passes the lowest point.

[0047] In addition to the above-described objects, features and advantages, the present invention has other objects, features and advantages. The present invention will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0049] In the attached figure:

[0050] Figure 1 is a schematic diagram of a wind turbine blade damage monitoring device according to this embodiment;

[0051] Figure 2 It is a schematic diagram of the projection of three groups of audio acquisition processors on the horizontal plane;

[0052] Figure 3 Schematic diagram of the coordinates of the lowest point of the blade and the location of the audio acquisition processor in this embodiment;

[0053] Figure 4 Schematic diagram of the coordinates of the lowest point of the blade and the position of the audio acquisition processor after changes in this embodiment;

[0054] Figure 5 : is a schematic diagram of the velocity decomposition of the observation point in this embodiment;

[0055] Among them, 1. Wind turbine blades; 1.1. The lowest point of wind turbine blades; 2. Network switches; 3. Edge computing servers; 4. Wind turbine towers. DETAILED DESCRIPTION

[0056] The embodiments of the present invention are described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered by the claims.

[0057] Example:

[0058] This embodiment discloses a wind turbine blade damage monitoring device and monitoring method. First, the wind turbine blade damage monitoring device in this embodiment is described:

[0059] like Figure 1 and Figure 2 As shown, the wind turbine blade damage monitoring device of this embodiment includes at least three groups of audio acquisition processors (preferably three groups in this embodiment) for collecting blade audio signals. The three groups of audio acquisition processors are respectively denoted as a first group of audio acquisition processors (denoted by C1), a second group of audio acquisition processors (denoted by C2), and a third group of audio acquisition processors (denoted by C3).

[0060] The three groups of audio acquisition processors are arranged along the circumference of the wind turbine tower 4. The three groups of audio acquisition processors are not in the same horizontal plane. Preferably, the specific installation form of the three groups of audio acquisition processors in this embodiment is: the first group of audio acquisition processors is arranged on the outer circumference of the tower, and the first group of audio acquisition processors is at the same height as the lowest point of the blade; the second group of audio acquisition processors and the third group of audio acquisition processors are both arranged on the ground, and the projections of the three groups of audio acquisition processors on the ground (i.e., the horizontal plane) are triangularly distributed (such as Figure 2 As shown in FIG, the lines connecting the projection points of the three groups of audio acquisition processors on the ground form an equilateral triangle.

[0061] like Figure 1 As shown, in this embodiment, the three groups of audio acquisition processors are all connected to the external solution system, specifically: the external solution system includes a network switch 2 and an edge solution server 3; the three groups of audio acquisition processors are connected to the edge solution server through the network switch, and the edge solution server is used to solve the information of the audio acquisition processor.

[0062] A fan blade damage monitoring method of this embodiment uses the above-mentioned fan blade damage monitoring device. The monitoring method includes steps S1 to S5, which are specifically as follows:

[0063] Step S1: Establish a three-dimensional coordinate system with the geometric center of the wind turbine base as the origin O, the east direction as the X axis, the north direction as the Y axis, and the vertical ground as the Z axis, as shown in the following example: Figure 3 As shown;

[0064] Step S2: First, obtain the coordinates of the lowest point of the fan blade (indicated by label 1.1) at time t0 and after time t, and then obtain the linear velocity v of the lowest point of the fan blade after time t from time t0. m ,like Figure 3 As shown, the details are as follows:

[0065] When t=0 (ie t0), the coordinates of the initial position point P0 of the lowest point of the fan blade can be expressed as: P0=(R Y sinθ0,R Y cosθ0,H,θ0);

[0066] The position P of the fan blade's lowest point after t time t The coordinates can be expressed as: P t =(R Y sinθ t , R Y cosθ t ,H,θ t );

[0067] Among them, R Yrepresents the radius of rotation of the lowest point of the wind turbine blade along the center of the tower base; θ0 is the angle between the line connecting the lowest point of the wind turbine blade and the origin O at time t0 and the X-axis; θ t is the angle between the projection of the line connecting the lowest point of the fan blade and the origin O on the XOY plane and the X axis after time t, that is, θ0 and θ t represents the direction of the lowest point of the fan blade at different times; H is the height of the lowest point of the fan blade from the ground; in this embodiment, the lowest point of the fan blade can also be called the wave source; θ t =ωt+θ0, ω represents the angular velocity of the fan blade, that is, the rotation from P0 to P t Angular velocity of position;

[0068] Get the linear velocity v of the fan blade's lowest point after moving for t time from time t0 m , as shown in formula 1):

[0069] v m =ωR Y 1);

[0070] Step S3: Get v m In C i and P t The component v″ on the connecting line, C i Indicates the location of an audio acquisition processor i;

[0071] First, the coordinate positions of the three groups of audio acquisition processors are explained;

[0072] The coordinates of the location of the first group of audio acquisition processors (denoted by C1) are expressed as C1(x1, y1, z1, η1). In this embodiment, C1 can be specifically expressed as: C1(0, R J , H,π / 2);

[0073] The coordinates of the location of the second group of audio acquisition processors (denoted by C2) are expressed as C2(x2, y2, z2, η2). In this embodiment, C2 can be specifically expressed as:

[0074] The coordinates of the location of the third group of audio acquisition processors (denoted by C3) are expressed as C3(x3, y3, z3, η3). In this embodiment, C3 can be specifically expressed as:

[0075] In this step S3, the third group of audio acquisition processors is used as an example for illustration, where C3 represents the location of the third group of audio acquisition processors; (x3, y3, z3) represents the coordinate value of C3 on the three-dimensional coordinate axis; η3 represents the angle between the projection of the line connecting C3 and the origin O on the base plane and the positive X axis in the counterclockwise direction; the same applies to C1, C2, and C3;

[0076] Because the third group of audio acquisition processors is used as an example in step S3, the following describes how to obtain v″ by taking C3 as an example, that is, obtaining v″ C3 :

[0077] Since the following steps S3.1 and S3.2 are described using the third group of audio acquisition processors as an example, the subscript i in the following formula is 3. Of course, if the second group of audio acquisition processors is used as an example, the subscript i in the following formula is 2. The specific process is as follows:

[0078] Step S3.1: Figure 4 Shown: Get the linear velocity v m In C i (i.e. C3) and P′ t The horizontal component v′ of the connecting line, i.e., along C3P′ t The weight of the t Indicates P t The projection point v′ on the horizontal plane (i.e., the ground) is obtained as shown in formula 2):

[0079]

[0080] Among them, R J represents the tower radius (i.e. the circumscribed circle radius of the above-mentioned equilateral triangle); η i (i.e. η3) is counterclockwise, C i The angle between the projection of the line connecting the origin O on the base plane and the positive X axis;

[0081] Furthermore, equation 2) is obtained by combining equations 2.1) to 2.5), which are specifically as follows:

[0082] In △P′ t OC i In the example, let the straight line OP′ t With straight line C i P′ t The included angle is α, and the direction of the velocity of the lowest point of the blade is parallel to the straight line C. i P′ t The angle between them is β; then v′ can be expressed as Equation 2.1);

[0083] v′=v m cosβ=v m sinα=ωR Y sinα 2.1);

[0084] Since the angle ∠α<π, we have formula 2.2):

[0085]

[0086] At the same time, in △P′ t OC i According to the law of cosines, we have Equations 2.3) and 2.4):

[0087]

[0088]

[0089] Substituting Equation 2.3) and Equation 2.4) into Equation 2.2) yields Equation 2.5):

[0090]

[0091] Substituting Equation 2.5) into Equation 2.1) yields Equation 2);

[0092] Step S3.2: Figure 5 As shown, solve the component v' in C i and P t The components v (i.e., the velocity of the observation point) and v″ on the connecting line are obtained as shown in Equation 3), which is as follows:

[0093]

[0094] Ju Zhong, R J Indicates the tower radius; η i In the counterclockwise direction, C i The angle between the projection of the line connecting the origin O on the base plane and the positive X axis; i Indicates C i Coordinate value on the X axis; y i Indicates C i The coordinate value on the Y axis; Z i Indicates C i In the Z-axis coordinate value, since i=3 is used as an example in this embodiment, the x i 、y i and Z i It is actually the value of C3 in the three-dimensional coordinate system;

[0095] Furthermore, by combining Equation 2), Equation 3.1) and Equation 3.2), Equation 3.1) and Equation 3.2) are as follows:

[0096] First, let the angle between v′ and v″ be σ, ∠C i P t P′ t For γ, we can get Equation 3.1):

[0097] v″=v′cosσ=v′sinγ 3.1);

[0098] At right angle △C i P t P′ t In the formula 3.2):

[0099]

[0100] Among them, P′ t The coordinates of P′ t (R Y sinθ t , R Y cosθ t ,z3,θ t );

[0101] From the above steps S3.1 and 3.2, we can get v m In P t The component on the line connecting the position and C3 (the position point where the third group of audio acquisition processors is located) is recorded as v″ C3 ;

[0102] Similarly, according to the above steps S3.1 and S3.2, v can be obtained. m In P t The component v″ on the line connecting the position and C1 C1 and v m In P t The component v″ on the line connecting the position and C2 C2 ;

[0103] Wherein, C1 represents the location of the first group of audio acquisition processors. Similarly, C2 represents the location of the second group of audio acquisition processors. That is, by repeating the above steps S3.1 and S3.2, v″ can be obtained. C1 、v″ C2 and v″ C3 ;

[0104] Step S4: Obtain the sound wave frequency f′ at the lowest point of the blade observed by the position point (i.e., observation point) where the audio acquisition processor i is located through the component v″ Ci ; Let the frequency of the sound wave at the lowest point of the blade be f′ Ci The audio time domain signal is P′ Ci , P′ Ci Converted into the original audio frequency domain signal F(P′ Ci ); F(P′ Ci ) is inversely deduced to obtain the real audio frequency domain signal F(P Ci ), as follows:

[0105] Step S4.1:

[0106] Under non-inertial motion, the observation point (i.e., the location of the audio acquisition processor) and the wave source (i.e., the lowest point of the blade) are not in the same direction of velocity. When the fan blade performs uniform circular motion around the center point of its base, the velocity direction is constantly changing. However, the velocity components of the sound wave source and the observation point on the line connecting them still satisfy the Doppler effect formula, as shown in Equation 4.1.

[0107]

[0108] Where f′ is the frequency of the sound wave observed at the observation point; u is the speed of the sound wave; v″ represents the speed of the observation point (i.e., the speed of the observation point relative to the sound wave source); f represents the actual frequency of the sound wave generated during the propagation process;

[0109] According to the Doppler effect formula 4.1), the sound wave frequency observed at the observation point is obtained, as shown in formula 4):

[0110]

[0111] Formula 4) is further specified in this embodiment as follows: the sound wave frequencies observed at the locations (observation points) of the three groups of audio acquisition processors are set to f′ C1 、f′ C2 and f′ C3 , as follows:

[0112]

[0113]

[0114]

[0115] Step S4.2: Let the observed sound wave frequency f′ at the lowest point of the blade be Ci The audio time domain signal is P′ Ci , that is, the audio time domain signals collected by the three observation points C1, C2 and C3 after Doppler effect interference are P′ C1 , P′ C2 and P′ C3 ;

[0116] The audio time domain signals (i.e. P′) observed at the three observation points are transformed into C1 , P′ C2 and P′ C3 ) is converted into the initial audio frequency domain signal, respectively denoted as F(P′ C1 ), F(P′ C2 ) and F(P′ C3 ), where F represents Fourier transform operation;

[0117] Step S4.3: Through formulas 4.a), 4.b) and 4.c), the three sets of initial audio frequency domain signals are reversed (i.e., F(P′) C1 ) corresponds to formula 4.a. Similarly, the other two groups of initial audio frequency domain signals correspond to formulas 4.b and 4.c respectively. The real audio frequency domain signals after eliminating the Doppler effect at the three observation points are obtained and are denoted as F(P C1 )、F(P C2 ) and F(P C3 );

[0118] Step S5: Through F(P Ci The audio frequency domain eigenvalues ​​of the blade without damage are compared with the real audio frequency domain signal to determine whether the blade is abnormal or damaged, as follows:

[0119] Step S5.1: Calculate the average value of the real audio frequency domain signal observed at the location of the three groups of audio acquisition processors, that is, calculate F(P C1 )、F(P C2 ) and F(P C3 ) to obtain the precise audio frequency domain data F(P) observed at the lowest point of the blade (i.e., the wave source) at different three-dimensional positions, as shown in Equation 5):

[0120] F(P)=AVERAGE(F(P C1 ), F(P C2 ), F(P C3 )) 5);

[0121] Step S5.3: Compare the precise audio frequency domain data F(P) with the audio frequency domain eigenvalues ​​of a normal, undamaged blade to determine whether the blade is abnormal or damaged. Specifically, when F(P) deviates from the audio frequency domain eigenvalues ​​of a normal, undamaged blade by a certain degree (the degree of deviation is selected based on the actual situation), the blade is determined to be damaged.

[0122] Wherein, F(P) represents the precise audio frequency domain data; AVERAGE represents the average value operation.

[0123] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for monitoring wind turbine blade damage, characterized in that: A wind turbine blade damage monitoring device is used, which includes at least three groups of audio acquisition processors for collecting blade audio signals; Multiple groups of audio acquisition processors are arranged along the circumference of the wind turbine tower and are not in the same horizontal plane; all three groups of audio acquisition processors are connected to an external solution system; Among the at least three groups of audio acquisition processors, the first group of audio acquisition processors is arranged on the wind turbine tower, and the second group of audio acquisition processors and the third group of audio acquisition processors are both arranged on the ground; The wind turbine blade damage monitoring method includes the following steps: Step S1: Establish a three-dimensional coordinate system with the geometric center of the wind turbine base as the origin O, the east direction as the X axis, the north direction as the Y axis, and the vertical ground as the Z axis; Step S2: Obtain the coordinates of the lowest point of the fan blade at time t0 and after time t; obtain the linear velocity v of the lowest point of the fan blade from time t0 to time t m ; Step S3: Get v m In C i and P t The component v″ on the connecting line, C i Indicates the location of an audio acquisition processor i; P t Indicates the coordinate point of the lowest point of the fan blade after time t; Step S4: Obtain the sound wave frequency f′ at the lowest point of the blade observed by the position where the audio acquisition processor i is located through the component v″ Ci ; Let f′ Ci The audio time domain signal is P′ Ci , P′ Ci Converted into the original audio frequency domain signal F(P′ Ci ); F(P′ Ci ) is inversely deduced to obtain the real audio frequency domain signal F(P Ci ); Step S5: Through F(P Ci ) is compared with the audio frequency domain characteristic value of a normal and undamaged blade to determine whether the blade is abnormal or damaged; The step S4 comprises: Step S4.1: Obtain the sound wave frequency f′ Ci , as shown in formula 4): Among them, u is the speed of sound waves; f represents the actual frequency of sound waves generated during propagation; Step S4.2: Let f′ Ci The audio time domain signal is P′ Ci , through Fourier transform, the audio time domain signal P′ Ci Converted into the original audio frequency domain signal F(P′ Ci ), where F represents Fourier transform operation; Step S4.3: Use formula 4) to convert the initial audio frequency domain signal F(P′) Ci ) is inversely deduced to obtain the real audio frequency domain signal F(P Ci ).

2. The wind turbine blade damage monitoring method according to claim 1, characterized in that: In the wind turbine blade damage monitoring device, the lines connecting the projection points of the three groups of audio acquisition processors in the horizontal plane form an equilateral triangle; the first group of audio acquisition processors is set at the same height as the lowest point of the blade.

3. The wind turbine blade damage monitoring method according to claim 1, characterized in that: The step S2 comprises: Step S2.1: The coordinate point of the lowest point of the fan blade at time t0 is P0 = (R Y sinθ0,R Y cosθ0,H,θ0); After time t, the coordinate point P of the lowest point of the fan blade t =(R Y sinθ t , R Y cosθ t ,H,θ t ); Among them, R Y represents the radius of rotation of the lowest point of the wind turbine blade along the center of the tower base; θ0 is the angle between the line connecting the lowest point of the wind turbine blade and the origin O at time t0 and the X-axis; θ t is the angle between the projection of the line connecting the lowest point of the fan blade and the origin O on the XOY plane and the X-axis after time t; H is the height of the lowest point of the fan blade from the ground; Step S2.2: Linear velocity v m As shown in formula 1): v m =ωRY 1); Where ω represents the angular velocity of the fan blades.

4. The wind turbine blade damage monitoring method according to claim 3, characterized in that: In step S3, v″ is obtained as follows: Step S3.1: Get the linear velocity v m In C i and P t 'component v' on the line; where P t ′ represents P t Projection point on the horizontal plane; Step S3.2: Solve for the component v′ in C i and P t The component v″ on the connecting line.

5. The wind turbine blade damage monitoring method according to claim 4, characterized in that: In step S3.1, v′ is obtained as shown in formula 2): Among them, R J Indicates the tower radius; η i In the counterclockwise direction, C i The angle between the projection of the line connecting the origin O on the base plane and the positive X axis.

6. The wind turbine blade damage monitoring method according to claim 4 or 5, characterized in that: In step S3.2, v″ is obtained as shown in formula 3): Among them, R J Indicates the tower radius; η i In the counterclockwise direction, C i The angle between the projection of the line connecting the origin O on the base plane and the positive X axis; i Indicates C i The coordinate value on the x-axis; y i Indicates C i The coordinate value on the Y axis; Z i Indicates C i The coordinate value on the z-axis.

7. The wind turbine blade damage monitoring method according to claim 6, characterized in that: The steps S5 includes: Step S5.1: Calculate the average value of the real audio frequency domain signals observed by the three groups of audio acquisition processors to obtain the precise audio frequency domain data F(P) observed at the lowest point of the blade at different three-dimensional positions, as shown in Equation 5): F(P)=AVERAGE(F(P C1 ),F(P C2 ),F(P C3 )) 5); Step S5.2: Compare the precise audio frequency domain data F(P) with the audio frequency domain characteristic values ​​of a normal, undamaged blade to determine whether the blade is abnormal or damaged; Among them, AVERAGE represents the average value operation; F(P C1 ) represents the real audio frequency domain signal observed by the first group of audio acquisition processors; F(P C2 ) represents the real audio frequency domain signal observed by the second group of audio acquisition processors; F(P C3 ) represents the real audio frequency domain signal observed by the third group of audio acquisition processors.

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