A method for measuring fan blade clearance distance using millimeter wave radar

Abstract

This invention provides a method for measuring the clearance distance of wind turbine blades using millimeter-wave radar, comprising: establishing a spatial rectangular coordinate system with the center of the wind turbine tower base as the origin; the axis of the wind turbine tower as the Z-axis; the east-west direction on the horizontal plane of the wind turbine tower as the X-axis and the north-south direction as the Y-axis; assuming the radius of the wind turbine tower base is r, the equivalent height of the tower is h, the distance from the tower axis to the rotation center of the blade is m, the equivalent length of the wind turbine blade is l, the coordinates of the rotation center of the wind turbine blade are S, and the coordinates of the tip of the wind turbine blade are T, calculating the coordinates P of the millimeter-wave radar; and then calculating the coordinates of the blade tip and the minimum clearance value. This invention measures the distance from the tip of the wind turbine blade to the radar in real time using the millimeter-wave ranging principle, calculates the minimum distance between the tip of the wind turbine blade and the surface of the tower through an algorithm, and when the minimum distance exceeds the safe design value of the blade clearance, promptly brakes or stops the wind turbine to ensure the structural safety of the wind turbine.

Description

Technical Field

[0001] This invention relates to the field of airspace protection technology for large wind turbine blades, and in particular to a method for measuring the airspace distance of wind turbine blades using millimeter-wave radar. Background Technology

[0002] The blade clearance of a wind turbine refers to the minimum distance between the blade tip and the tower surface during turbine operation, and it is crucial for the safety of the wind turbine. Currently, wind turbines are becoming increasingly powerful, and their blades are also becoming longer. With the increase in blade length, blade stiffness decreases accordingly. At higher wind speeds, the deformation at the blade tip is significant, and under extreme turbulence conditions, this can lead to serious accidents such as blade tip swiping the tower, affecting the safe operation of the wind turbine. Therefore, real-time monitoring of whether the blade clearance remains within the designed safe range is of paramount importance for ensuring the safety of the wind turbine.

[0003] Currently, the main airspace monitoring technology solutions available on the market are as follows:

[0004] (1) Installing video cameras or lidar on the nacelle. This solution mainly utilizes optical methods to detect the blades, that is, reconstructing the three-dimensional model of the blades through machine vision or lidar point cloud algorithms, and then calculating the clearance between the blades and the tower. This method is easily affected by adverse weather conditions such as rain, fog, and snow, as well as poor visibility at night. Furthermore, the accuracy of the calculation results is highly dependent on the algorithm. Currently, the technology is not mature. At the same time, the calculation of image or point cloud data requires a large amount of computing resources. Therefore, the reliability and cost of this technical solution are not ideal.

[0005] (2) Multiple millimeter-wave radars are evenly distributed along the circumference on the tower at a position flush with the tip of the wind turbine blades. The clearance distance is calculated by measuring the distance with the radar. Compared with placing the radar at the base of the tower, this method transforms the calculation method from a three-dimensional spatial problem to a two-dimensional planar problem, greatly simplifying the calculation method. However, it is very difficult to implement. On the one hand, the installation location of wind turbines is often remote and the terrain is steep; on the other hand, the tip of the wind turbine blades is generally about 20 meters above the ground, requiring a large aerial work platform to operate. Summary of the Invention

[0006] This invention provides a method for measuring the clearance distance of wind turbine blades using millimeter-wave radar, comprising the following steps:

[0007] Step 1: Take the center of the wind turbine tower base as the origin of the coordinate system; take the axis of the wind turbine tower as the Z-axis; and establish a spatial rectangular coordinate system on the horizontal plane of the wind turbine tower with the east-west direction as the X-axis and the north-south direction as the Y-axis.

[0008] Step 2: Let the radius of the wind turbine tower base be r, the equivalent height of the tower be h, the distance from the tower axis to the rotation center of the blade be m, the equivalent length of the wind turbine blade be l, the coordinates of the rotation center of the wind turbine blade be S, and the coordinates of the tip of the wind turbine blade be T; calculate the coordinates P of the millimeter-wave radar; where: r, h, m, and l are all known parameters, S = (X, Y, h), T = (X, Y, Z), P = (P1, ... P n ), where n is a natural number greater than or equal to 1;

[0009] Step 3: Calculate the blade tip coordinates and minimum clearance value based on the millimeter-wave radar coordinates P.

[0010] Optionally, when calculating the blade tip coordinates and minimum clearance based on the coordinates P of the millimeter-wave radar, two millimeter-wave radars are grouped together. When two or more millimeter-wave radars can simultaneously capture distance data, the following process is used to calculate the blade tip coordinates:

[0011] Let the two millimeter-wave radars be numbered P1 and P2 respectively. Acquire the measurement data of the two millimeter-wave radars numbered P1 and P2. Record the measurement data of the millimeter-wave radar numbered P1 as S1 and the coordinates of the millimeter-wave radar numbered P1 as (a,b,0). Record the measurement data of the millimeter-wave radar numbered P2 as S2 and the coordinates of the millimeter-wave radar numbered P2 as (c,d,0).

[0012] Based on |P1T|=S1, we obtain the following formula:

[0013] (Xa) 2 +(Yb) 2 +Z 2 =S1 2 ,

[0014] Based on |P2T|=S2, we obtain the following formula:

[0015] (Xc) 2 +(Yd) 2 +Z 2 =S2 2 ,

[0016] Based on |ST|=l, we obtain the following formula:

[0017] (X-X1) 2 +(Y-Y1) 2 +(Zh) 2 =l 2 ,

[0018] Based on the distance *m* from the tower axis to the blade rotation center, the constraint equations are obtained:

[0019] X1 2+Y1 2 =m 2 ,

[0020] The projection of the wind turbine blade's rotation center point S, the wind turbine blade tip point T, onto the horizontal plane, along with the origin, are collinear, and the following relationship exists:

[0021]

[0022] Solve the above 5 equations to get the coordinates of the blade tip (X,Y,Z,X1,Y1).

[0023] Optionally, when calculating the blade tip coordinates and minimum clearance based on the millimeter-wave radar coordinates P, if only one millimeter-wave radar can simultaneously capture distance data, the following process is used to calculate the blade tip coordinates:

[0024] Let the number of the millimeter-wave radar be P1. Acquire the measurement data of the millimeter-wave radar numbered P1 and record the measurement data of the millimeter-wave radar numbered P1 as S1. The coordinates of the millimeter-wave radar numbered P1 are (a,b,0). At the same time, measure the angle between the orientation of the wind turbine nacelle and the X-axis square as θ.

[0025] Based on |P1T|=S1, we obtain the following formula:

[0026] (Xa) 2 +(Yb) 2 +Z 2 =S1 2 ,

[0027] Based on |ST|=l, we obtain the following formula:

[0028] (X-X1) 2 +(Y-Y1) 2 +(Zh) 2 =l 2 ,

[0029] Based on the cabin orientation angle θ, we obtain:

[0030]

[0031] The projection of the wind turbine blade's rotation center point S, the wind turbine blade tip point T, onto the horizontal plane, along with the origin, are collinear, and the following relationship exists:

[0032]

[0033] Solve the above 5 equations to get the coordinates of the blade tip (X,Y,Z,X1,Y1).

[0034] Optionally, since radar measures continuously, there will be many sets of measurement data at the point where the blade approaches and leaves the minimum clearance. However, there will inevitably be a set that minimizes the clearance value. The corresponding blade tip coordinates at this point are the coordinates of the minimum clearance. The blade tip coordinates corresponding to the minimum clearance value can be calculated using the following formula:

[0035]

[0036] The minimum clearance value is calculated based on the blade tip coordinates corresponding to the minimum clearance value:

[0037]

[0038] Where R represents the tower radius at the same horizontal plane as the blade tip.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] This invention installs a millimeter-wave radar at the base of the wind turbine tower. It uses the millimeter-wave ranging principle to measure the distance from the tip of the wind turbine blade to the radar in real time. The algorithm calculates the minimum distance between the tip of the wind turbine blade and the surface of the tower. When the minimum distance exceeds the safe design value of the blade clearance, it can promptly remind the wind turbine management personnel to perform braking or shutdown operations to ensure the structural safety of the wind turbine.

[0041] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the figures. Attached Figure Description

[0042] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0043] Figure 1 This is a schematic diagram of the overall process of a method for measuring the clearance distance of wind turbine blades using millimeter-wave radar in an embodiment of the present invention;

[0044] Figure 2 This is a schematic diagram illustrating the calculation principle when two radars scan data in this invention;

[0045] Figure 3 This is a schematic diagram illustrating the calculation principle when only one radar detects data in this invention;

[0046] Figure 4 This is a schematic diagram of the geometric relationships of the parameters of the horizontal projection of the wind turbine in this invention. Detailed Implementation

[0047] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0048] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein in the specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0049] This embodiment:

[0050] This invention involves installing multiple millimeter-wave radar devices around the base of a wind turbine tower (the specific number of radars is determined by the radar's measurement field of view, requiring 360-degree coverage of the operating area of ​​the wind turbine blades around the tower, with some overlap being preferable), to measure the straight-line distance between the tip of the wind turbine blades and the millimeter-wave radar in real time, and then using an algorithm to calculate the clearance distance between the tip of the wind turbine blades and the surface of the tower.

[0051] See Figures 1 to 4 As shown, the present invention provides a method for calculating the clearance distance between the tip of the wind turbine blades and the surface of the tower by installing multiple millimeter-wave radar devices around the base of the wind turbine tower (the specific number of millimeter-wave radars is determined by the measurement field of view of a single millimeter-wave radar, with the aim of being able to cover the operating area of ​​the wind turbine blades around the tower in 360 degrees, and with some overlap being preferred), and measuring the straight-line distance between the tip of the wind turbine blades and the millimeter-wave radar in real time.

[0052] The present invention provides a method for measuring the clearance distance of wind turbine blades using millimeter-wave radar, comprising the following steps:

[0053] Step 1: Take the center of the wind turbine tower base as the origin O (O = (0, 0, 0)); take the axis of the wind turbine tower as the Z-axis; and establish a spatial rectangular coordinate system on the horizontal plane of the wind turbine tower with the east-west direction as the X-axis and the north-south direction as the Y-axis.

[0054] Step 2: Let the radius of the wind turbine tower base be r, the equivalent height of the tower be h, the distance from the tower axis to the rotation center of the blade be m, and the equivalent length of the wind turbine blade be l, where r, h, m, and l are all known parameters; the coordinates of the rotation center of the wind turbine blade are S (S = (X, Y, h)), and the coordinates of the tip of the wind turbine blade are T (T = (X, Y, Z)).

[0055] Since multiple millimeter-wave radars are evenly distributed around the circumference of the tower base, their coordinates can be calculated. In this embodiment, taking eight millimeter-wave radars evenly distributed as an example, the coordinates of these eight millimeter-wave radars (P1, P2, P3, P4, P5, P6, P7, P8) are as follows:

[0056]

[0057] P2 = (r, 0, 0),

[0058]

[0059] P4 = (0, -r, 0),

[0060]

[0061] P6 = (-r, 0, 0),

[0062]

[0063] P8 = (0, r, 0).

[0064] Step 3: Since multiple millimeter-wave radars are evenly distributed around the tower base and the scanning areas of multiple millimeter-wave radars overlap to some extent, multiple millimeter-wave radars can measure distance data at the same time during the rotation of the wind turbine blades. The following uses the example of two millimeter-wave radars scanning distance data at the same time to explain the algorithm for calculating the blade tip coordinates and minimum clearance value.

[0065] S3.1 Determining if multiple millimeter-wave radars can simultaneously scan distance data: ① If three or more millimeter-wave radars simultaneously scan distance data, it can be considered a special case of two or more groups of two millimeter-wave radars; ② If only one radar measures the distance data, it can be used in conjunction with the wind turbine azimuth angle to calculate the blade clearance distance.

[0066] S3.2 When two or more sets of millimeter-wave radars can simultaneously capture range data, the following process is used to calculate the blade tip coordinates and minimum clearance value:

[0067] Ⅰ. Calculate the coordinates of the blade tip

[0068] Acquire the measurement data of two millimeter-wave radars numbered P1 and P2, and denote the measurement data of the millimeter-wave radar numbered P1 as S1 and the coordinates of the millimeter-wave radar numbered P1 as (a,b,0), and denote the measurement data of the millimeter-wave radar numbered P2 as S2 and the coordinates of the millimeter-wave radar numbered P2 as (c,d,0).

[0069] Based on |P1T|=S1, we obtain the following formula:

[0070] (Xa) 2 +(Yb) 2 +Z 2 =S1 2 ,

[0071] Based on |P2T|=S2, we obtain the following formula:

[0072] (Xc) 2 +(Yd) 2 +Z 2 =S2 2 ,

[0073] Based on |ST|=l, we obtain the following formula:

[0074] (X-X1) 2 +(Y-Y1) 2 +(Zh) 2 =l 2 ,

[0075] Based on the distance *m* from the tower axis to the blade rotation center, the constraint equations are obtained:

[0076] X1 2 +Y1 2 =m 2 ,

[0077] Given that when the blade clearance reaches its minimum, the equivalent straight line l of the blade must be coplanar with the tower axis h, and this plane is perpendicular to the horizontal plane. The projection of the wind turbine blade rotation center point S, the wind turbine blade tip point T, and the origin on the horizontal plane are collinear, and the following relationship exists:

[0078]

[0079] By solving the above five equations simultaneously and considering the relevant practical constraints, we can obtain five unknowns (X, Y, Z, X1, Y1).

[0080] II. Calculate the minimum clearance value

[0081] Since the two millimeter-wave radars measure continuously, there will be many sets of measurement data {S1,S2} near and away from the minimum clearance of the blade. However, there must exist a set of {S1,S2} that minimizes the clearance value. The corresponding blade tip coordinates at this point are the coordinates of the minimum clearance. The blade tip coordinates corresponding to the minimum clearance value are calculated using the following formula:

[0082]

[0083] The minimum clearance value is calculated based on the blade tip coordinates corresponding to the minimum clearance value:

[0084]

[0085] Where R represents the tower radius at the same horizontal plane as the blade tip.

[0086] When only one millimeter-wave radar measures the distance data, and simultaneously measures the angle θ between the wind turbine nacelle orientation and the X-axis square, the following process is used to calculate the blade tip coordinates and minimum clearance value:

[0087] i. Calculate the coordinates of the blade tip

[0088] Acquire the measurement data of the millimeter-wave radar numbered P1, and denote the measurement data of the millimeter-wave radar numbered P1 as S1, and the coordinates of the millimeter-wave radar numbered P1 as (a,b,0).

[0089] Based on |P1T|=S1, we obtain the following formula:

[0090]

[0091] Based on |ST|=l, we obtain the following formula:

[0092] (X-X1) 2 +(Y-Y1) 2 +(Zh) 2 =l 2 ,

[0093] Based on the cabin orientation angle θ, we obtain:

[0094]

[0095] Given that when the blade clearance reaches its minimum, the equivalent straight line l of the blade must be coplanar with the tower axis h, and this plane is perpendicular to the horizontal plane. The projection of the wind turbine blade rotation center point S, the wind turbine blade tip point T, and the origin on the horizontal plane are collinear, and the following relationship exists:

[0096]

[0097] By solving the above five equations simultaneously and considering the relevant practical constraints, we can obtain five unknowns (X, Y, Z, X1, Y1).

[0098] ii. Calculate the minimum clearance value

[0099] Since millimeter-wave radar performs continuous measurements, there will be many sets of measurement data {S1} near and away from the minimum clearance on the blade. However, there must exist a set of {S1} that minimizes the clearance value. The corresponding blade tip coordinates at this point are the coordinates of the minimum clearance. The blade tip coordinates corresponding to the minimum clearance value are calculated using the following formula:

[0100]

[0101] The minimum clearance value is calculated based on the blade tip coordinates corresponding to the minimum clearance value:

[0102]

[0103] Where R represents the tower radius at the same horizontal plane as the blade tip.

[0104] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for measuring the clearance distance of wind turbine blades using millimeter-wave radar, characterized in that, Includes the following steps: Step 1: Take the center of the wind turbine tower base as the origin of the coordinate system; the axis of the wind turbine tower as... The axis is positioned east-west on the horizontal plane of the wind turbine tower. Axis, north-south direction as Establish a spatial rectangular coordinate system using axes; Step 2: Let the radius of the wind turbine tower base be... The equivalent height of the tower is The distance from the tower axis to the center of rotation of the blade is The equivalent length of the wind turbine blades is The coordinates of the center point of rotation of the wind turbine blades are The coordinates of the tip of the wind turbine blade are ; Calculate the coordinates of millimeter-wave radar ;in: , , , All parameters are known. , , , Take a natural number greater than or equal to 1; Step 3: Coordinates based on millimeter-wave radar Calculate the blade tip coordinates and minimum clearance value; In millimeter-wave radar-based coordinates When calculating the blade tip coordinates and minimum clearance, two millimeter-wave radars are grouped together. When two or more millimeter-wave radars can simultaneously capture distance data, the following process is used to calculate the blade tip coordinates: Let the two millimeter-wave radars be numbered as follows: and Get the number as and Measurement data from two millimeter-wave radars, and numbered as follows: The measurement data of the millimeter-wave radar is denoted as Numbered The coordinates of the millimeter-wave radar are as follows , will be numbered The measurement data of the millimeter-wave radar is denoted as Numbered The coordinates of the millimeter-wave radar are as follows ; according to We obtain the following formula: ， according to We obtain the following formula: ， according to We obtain the following formula: ， Based on the distance from the tower axis to the blade rotation center The constraint equations are obtained as follows: ， The coordinates of the rotation center of the wind turbine blades are The coordinates of the point and the tip of the wind turbine blade are: When the projection point on the horizontal plane is collinear with the origin, the following relationship exists: ， Solve the above 5 equations simultaneously to obtain the coordinates of the blade tip. .

2. The method for measuring the clearance distance of wind turbine blades using millimeter-wave radar according to claim 1, characterized in that, In millimeter-wave radar-based coordinates When calculating the blade tip coordinates and minimum clearance, if only one millimeter-wave radar can simultaneously capture distance data, the following process is used to calculate the blade tip coordinates: Let the number of this millimeter-wave radar be... Get the number as The measurement data from the millimeter-wave radar, and numbered as The measurement data of the millimeter-wave radar is denoted as Numbered The coordinates of the millimeter-wave radar are as follows At the same time, the orientation of the wind turbine nacelle was measured. The included angle of the axial square is ; according to We obtain the following formula: ， according to We obtain the following formula: ， According to the cabin orientation angle get: ， The coordinates of the rotation center of the wind turbine blades are The coordinates of the point and the tip of the wind turbine blade are: When the projection point on the horizontal plane is collinear with the origin, the following relationship exists: ， Solve the above 5 equations simultaneously to obtain the coordinates of the blade tip. .

3. The method for measuring the clearance distance of wind turbine blades using millimeter-wave radar according to claim 1 or 2, characterized in that, The blade tip coordinates corresponding to the minimum clearance value are calculated using the following formula: ； The minimum clearance value is calculated based on the blade tip coordinates corresponding to the minimum clearance value: ， in, This indicates the tower radius at the same horizontal plane as the blade tip.

Images