A wind turbine tower clearance monitoring system and method

Abstract

This invention provides a wind turbine tower clearance monitoring system and method, including a circular track, a mobile trolley, a camera device, an infrared thermal imager, a first lighting spotlight, a second lighting spotlight, a data acquisition and transmission module, a central processing unit, and a control module. The circular track is installed on the ground at the bottom of the tower, the mobile trolley is installed on the circular track, the camera device is installed on the mobile trolley, and the camera device simultaneously captures images of the blade tip position and the corresponding tower position. The infrared thermal imager is installed on the mobile trolley and captures images of the blade tip. The control module controls the mobile trolley to synchronize with the nacelle yaw. The monitoring system is installed at the bottom of the tower, close to the blade tip position, resulting in less imaging interference, higher clarity, higher accuracy in calculating the tower clearance value, and a lower probability of error. It is also convenient for maintenance and installation, and the position of the monitoring system can be adjusted according to the nacelle yaw angle to facilitate the monitoring of the tower clearance.

Description

Technical Field

[0001] This invention relates to the field of tower clearance monitoring technology, specifically to a wind turbine tower clearance monitoring system and method. Background Technology

[0002] The tower clearance of a wind turbine refers to the minimum distance between the blade tip and the tower as the blade passes over it during rotor rotation. As the capacity of individual wind turbines, rotor diameters, and blade lengths increase, the clearance between the tower and the blades becomes increasingly crucial. When a wind turbine experiences rotor failure or defects in blade design and manufacturing, insufficient tower clearance can lead to serious malfunctions such as blade-to-tower collisions. Therefore, real-time monitoring of tower clearance has become a key research area in the wind power industry to ensure the safe operation of wind turbines.

[0003] Currently, image-based air clearance monitoring is a mainstream technology for tower clearance monitoring. Several companies have proposed different tower clearance monitoring schemes based on this technology, each with its own advantages. For example, patent CN202310438068.7 discloses a wind turbine tower clearance monitoring system and method that combines video clearance monitoring with infrared thermal imaging technology to monitor tower clearance, ensuring effective monitoring even in low light conditions. However, this tower clearance monitoring system also has some drawbacks:

[0004] (1) High-definition cameras and infrared thermal imagers are usually installed at the bottom of the cabin, which is far from the blade tip. It is difficult to achieve high-definition capture and distinguish the blade tip position and the tower position that is close to the blade tip.

[0005] (2) Due to the obstruction of the bottom of the cabin, the infrared thermal imager can only shoot and capture the position of the blades at an angle downwards. It inevitably captures ground objects and is easily interfered with by the infrared imaging of objects with higher ground temperatures. For example, the infrared imaging of cars, machinery and equipment and large animals on the ground may affect the clarity of the infrared imaging of the blades.

[0006] (3) The main monitoring equipment is installed at the bottom of the cabin, which is high above the ground. The lenses of the high-definition cameras and infrared thermal imagers are not easy to clean after being contaminated or blocked by sand and soil, and the equipment is inconvenient to maintain. Summary of the Invention

[0007] To address the aforementioned problems in the existing technology, this invention provides a wind turbine tower clearance monitoring system and method. The monitoring system is installed at the bottom of the tower, close to the blade tip, resulting in minimal imaging interference, high clarity, high accuracy in calculating the tower clearance value, low error probability, and ease of maintenance and installation. Furthermore, the position of the monitoring system can be adjusted according to the nacelle yaw angle to facilitate tower clearance monitoring.

[0008] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0009] A wind turbine tower clearance monitoring system, the wind turbine tower clearance monitoring system comprising:

[0010] A circular track is installed on the ground at the bottom of the tower and is coaxially mounted with the tower.

[0011] A mobile trolley is mounted on a circular track and is driven to move along the circular track by a travel drive motor.

[0012] The camera device is mounted on a mobile trolley and located below the tower and the blade tip. The camera lens points upwards. When the blade passes the tower position, the camera device simultaneously captures the blade tip position and the tower position at the corresponding height.

[0013] An infrared thermal imager is mounted on a mobile trolley and positioned below the tower and the blade tip. The lens of the infrared thermal imager is pointed in the direction the blade turns in. The angle θ1 of the lens in the horizontal direction towards the blade turning in is 30° to 75°, and the angle θ2 between the lens and the ground is 45° to 80° to capture images of the blade tip.

[0014] The first and second spotlights are both mounted on a mobile trolley and shine obliquely upwards toward the blades and the tower, respectively.

[0015] The data acquisition and transmission module is connected to the camera device and the infrared thermal imager to receive image data from the camera device and the infrared thermal imager.

[0016] The central processing unit is connected to the data acquisition and transmission module, receives data information sent by the data acquisition and transmission module, identifies the position of the tower and blade tip, and sends the nacelle yaw angle data information to the data acquisition and transmission module.

[0017] The control module, connected to the data acquisition and transmission module, contains an inertial measurement module and a light sensor. The inertial measurement module is mounted on the moving trolley and monitors the angle of rotation of the trolley around the tower. The control module transmits the data from the inertial measurement module to the central processing unit via the data acquisition and transmission module and receives the yaw angle data of the nacelle. The control module is connected to the traveling drive motor of the moving trolley and controls the moving trolley to yaw synchronously with the nacelle. The light sensor transmits the monitored ambient light intensity data to the control module and the data acquisition and transmission module. The control module controls the infrared thermal imager, the first illumination spotlight, and the second illumination spotlight to turn on or off based on the magnitude of the light intensity data.

[0018] The upper surface of the circular track is a rough surface. The moving trolley includes a car body and running wheels connected to the bottom of the car body. The running wheels of the moving trolley are in contact with the upper surface of the circular track. The running wheels are connected to a running drive motor, which drives the running wheels to move along the upper surface of the circular track.

[0019] The circular track has grooves on both sides, and the bottom of the moving trolley is equipped with two sets of anti-tilt wheels. The two sets of anti-tilt wheels are respectively hung upside down in the grooves on both sides of the circular track. When the moving trolley moves, the anti-tilt wheels move synchronously in the grooves.

[0020] The first and second spotlights use different colors of light.

[0021] The installation angles of the first and second spotlights are adjustable.

[0022] The up-down pointing angle of the lens of the camera device is adjustable.

[0023] The angle between the lens of the infrared thermal imager and the ground is adjustable.

[0024] The annular track is installed on the ground by a support frame, and one or more support frames are distributed at the bottom of the annular track; the annular track is embedded in the entrance step of the tower door, and the height of the upper surface of the annular track is flush with the height of the step into which it is embedded.

[0025] This invention also provides a monitoring method for a wind turbine tower clearance monitoring system, comprising the following steps:

[0026] S1. Select a suitable diameter circular track, and install the circular track, moving trolley, camera device, infrared thermal imager, first lighting spotlight, second lighting spotlight, data acquisition and transmission module and control module as required. Record the diameter R1 of the circular track, the angle β between the lens of the camera device and the ground, the angle θ1 of the lens of the infrared thermal imager in the horizontal direction towards the blade turning side, and the angle θ2 between the lens of the infrared thermal imager and the ground.

[0027] S2. The control module records the initial position of the mobile trolley. When the nacelle yaws, the central processing unit transmits the yaw angle to the control module through the data acquisition and transmission module. The control module sends an action command to the travel drive motor based on the received yaw angle data. The travel drive motor drives the entire mobile trolley to move towards the nacelle position after yaw. At the same time, the inertial measurement module monitors in real time and feeds back to the control module the angle by which the mobile trolley has moved around the tower. When the moving angle of the mobile trolley is the same as the nacelle yaw angle, the mobile trolley stops moving.

[0028] S3. Based on the angle β between the camera lens and the ground, the angle θ1 of the infrared thermal imager lens in the horizontal direction towards the blade's inward side, the angle θ2 between the infrared thermal imager lens and the ground, the relative position parameters of the camera device and the infrared thermal imager on the moving trolley, and the structural dimensions of the camera device and the infrared thermal imager, the relative position and relative shooting angle of the camera lens and the infrared thermal imager lens in three-dimensional space can be determined.

[0029] S4. During the operation of the wind turbine, the camera device captures images of the tower and blade tips in real time and transmits the image data to the data acquisition and transmission module; the light sensor monitors the ambient light intensity data in real time and transmits it to the control module and the data acquisition and transmission module; the data acquisition and transmission module transmits the received image data and ambient light intensity data to the central processing unit.

[0030] S5. When the ambient light intensity is greater than the set threshold, the control module turns off the infrared thermal imager, the first illumination spotlight, and the second illumination spotlight. The image processing software of the central processing unit, based on the image of the tower and blade tip captured by the camera device, determines the position and relative distance of the tower and blade tip in the image according to the shape and grayscale characteristics of the tower and blade tip. Then, based on the ratio of the image size to the actual size, it calculates the minimum distance between the tower and the blade tip, i.e., the tower clearance value.

[0031] S6. When the ambient light intensity is less than or equal to the set threshold, the following two monitoring methods will be performed simultaneously:

[0032] S6.1 The control module turns on the infrared thermal imager, the first lighting spotlight and the second lighting spotlight. The camera device captures images of the tower and blade tips above in real time and transmits the image data to the central processing unit via the data acquisition and transmission module. The central processing unit calculates the tower clearance value according to step S5.

[0033] S6.2. While performing the monitoring method described in S6.1 above, an infrared thermal imager is used to capture images of the blade tips. The image data is then transmitted to the central processing unit via the data acquisition and transmission module. The image processing software of the central processing unit combines the blade tip images captured by the infrared thermal imager and the tower images captured by the camera device based on the relative positions and relative shooting angles of the lens of the camera device and the lens of the infrared thermal imager in three-dimensional space. The blade tips of the same blade at different positions during one revolution of the impeller are connected into a line, and this line is extended to the position of the tower in the composite image. The distance between the extended line and the tower in the composite image is the representation of the tower clearance value in the image. Based on the ratio of the image size to the actual size, the actual tower clearance value can be calculated.

[0034] S7. When any of the tower clearance values ​​calculated in S5, S6.1, and S6.2 above reach the set threshold, an early warning message will be issued.

[0035] In step S6.2, the trajectory of the blade tip image captured by the camera device at the same wind speed when the ambient light intensity is greater than a set threshold is used as a correction reference for the extension line of the blade tip trajectory captured by the infrared thermal imager.

[0036] Compared with the prior art, the beneficial effects of the present invention are: 1. The wind turbine tower clearance monitoring system provided by the present invention monitors the tower clearance through a camera device and an infrared thermal imager. It uses two methods to monitor and calculate the tower clearance value simultaneously in environments with poor ambient light, resulting in a large safety redundancy.

[0037] 2. In this invention, both the camera device and the infrared thermal imager are installed at the bottom of the tower, close to the blade tip. This allows for high-definition capture and differentiation of the blade tip position and the tower position close to the blade tip, resulting in high accuracy and low error probability in calculating the tower clearance value. Furthermore, the infrared thermal imager shoots and captures the blade tip position at an angle upwards, avoiding interference from images of objects with higher ground temperatures. This results in high clarity of the blade infrared image, further improving the accuracy of clearance monitoring in low-light conditions. It also facilitates maintenance and installation.

[0038] 3. In this invention, the camera device and infrared thermal imager are mounted on a circular track by a mobile trolley. When the nacelle yaws, the control module controls the mobile trolley to move the camera device and infrared thermal imager around the tower along the circular track according to the nacelle yaw angle, so that the camera device and infrared thermal imager can always be located below the tower and the blade tip, that is, below the nacelle, which facilitates the tower clearance monitoring system to monitor the tower clearance after the nacelle yaws.

[0039] 4. In this invention, the first and second lighting spotlights of different colors illuminate the blades and the tower respectively, which can improve the distinguishability of the blade tips and the tower in environments with poor light.

[0040] 5. In this invention, the surface of the ring track is flat and does not easily accumulate sand, gravel or liquid water. The trolley is mounted on the grooves on both sides of the ring track by anti-tilt wheels, which can prevent tilting during the movement of the trolley.

[0041] 6. In this invention, the annular track is embedded in the entrance steps of the tower door, and the height of the upper surface of the annular track is level with the height of the steps into which it is embedded. This allows the mobile trolley to rotate 360° around the tower without affecting the normal entry and exit of staff through the tower door.

[0042] 7. In this invention, the image trajectory of the blade tip captured by the camera device at the same wind speed when the ambient light intensity is greater than a set threshold is used as a correction reference for the extension line of the blade tip trajectory captured by the infrared thermal imager, thereby further improving the accuracy of drawing the extension line of the blade tip trajectory captured by the infrared thermal imager and the accuracy of the tower clearance value under this monitoring method. Attached Figure Description

[0043] Figure 1 This is an installation diagram of the wind turbine tower clearance monitoring system provided by the present invention.

[0044] Figure 2 for Figure 1 A magnified schematic diagram of part A in the middle;

[0045] Figure 3 This is a schematic diagram showing the connection between the annular track and the support frame in this invention;

[0046] Figure 4 This is a schematic diagram of the circular track in this invention;

[0047] Figure 5 This is a schematic diagram of the structure of the mobile vehicle in this invention;

[0048] Figure 6 This is a schematic diagram showing the connection between the mobile trolley and the circular track in this invention;

[0049] Figure 7 This is a top view schematic diagram of the arrangement of the camera device, infrared thermal imager, etc. on the mobile vehicle in this invention;

[0050] Figure 8 This is a schematic diagram of the arrangement of the camera device, infrared thermal imager, etc. on the mobile vehicle in this invention;

[0051] In the diagram: 1-Circular track, 101-Groove, 2-Mobile trolley, 201-Car body, 202-Drive motor, 203-Walking wheel, 204-Anti-tilt wheel, 3-Camera device, 4-Infrared thermal imager, 5-Tower, 6-Support frame, 7-Entrance step, 801-First bracket, 802-First drive shaft, 803-First drive motor, 901-Second bracket, 902-Second drive shaft, 903-Second drive motor, 10-First spotlight, 11-Second spotlight, 12-Data acquisition and transmission module and control module. Detailed Implementation

[0052] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0053] The installation diagram of the wind turbine tower clearance monitoring system provided in this invention is as follows: Figure 1 and Figure 2 As shown, it includes a circular track 1, a mobile trolley 2, a camera device 3, an infrared thermal imager 4, a first lighting spotlight 10, a second lighting spotlight 11, a data acquisition and transmission module and a control module 12, as well as a central processing unit. The data acquisition and transmission module and the control module are integrated into one unit in the figure.

[0054] The circular track is installed on the ground at the bottom of the tower and is coaxial with tower 5, see... Figure 1 Specifically, the circular track is installed on the ground via support frame 6. Further, the bottom of the support frame is supported on the ground, and the top of the support frame is connected to the circular track by adhesive or bolts. In this embodiment, one or more support frames are distributed at the bottom of the circular track; the specific number is set according to need. In the figure, six support frames are evenly distributed. Figure 3 To ensure that the camera and infrared thermal imager are positioned below the tower and blade tips, the diameter of the circular track should be appropriately selected based on the overall size of the wind turbine.

[0055] The mobile trolley is mounted on a circular track. In this embodiment, the upper surface of the circular track is a rough surface, and grooves 101 are provided on both sides of the circular track. Figure 4 As shown. Furthermore, the grooves on both sides of the circular track are at the same height. The mobile trolley includes a body 201, a drive motor 202, and wheels 203 and two sets of anti-roll wheels 204 connected to the bottom of the body, as shown. Figure 5 As shown. The traveling wheels of the mobile trolley are in contact with the upper surface of the circular track. The traveling wheels are connected to the travel drive motor. Two sets of anti-tilt wheels are respectively hooked up to the grooves on both sides of the circular track, as shown. Figure 2 and Figure 6As shown. The travel drive motor drives the travel wheels to rotate. Because the upper surface of the circular track is rough, there is friction between the travel wheels and the upper surface of the circular track, thus providing a forward traction force, causing the travel wheels to move along the upper surface of the circular track. The anti-tilt wheels move synchronously within the grooves, thereby driving the trolley to move along the circular track via the travel drive motor. Specifically, the bottom of the trolley has two travel wheels at the front and two at the rear. The two front travel wheels are connected to the travel drive motor and are the driving wheels, while the two rear travel wheels are the driven wheels. Each set of anti-tilt wheels includes two anti-tilt wheels, which prevent the trolley from tilting.

[0056] In this embodiment, the annular track is embedded in the entrance step 7 of the tower gate, and the height of the upper surface of the annular track is flush with the height of the step in which it is embedded. Figure 1 While allowing the mobile trolley to rotate 360° around the tower, it does not obstruct staff from entering and exiting the tower doors.

[0057] In this embodiment, the camera device is a high-definition camera with a wide-angle lens. The camera device is mounted on the body of the mobile trolley and located below the tower and the blade tip. The lens of the camera device points upward. When the blade passes the tower position, the camera device simultaneously captures the blade tip position and the tower position at the corresponding height.

[0058] In this embodiment, the vertical pointing angle of the camera lens is adjustable. Specifically, a first bracket 801 is fixed on the mobile carriage, and a first drive shaft 802 and a first drive motor 803 are connected to the first bracket. The camera device is fixedly connected to the first drive shaft, and the first drive motor is connected to the first drive shaft and drives the first drive shaft to rotate, thereby adjusting the vertical pointing angle of the camera lens. Adjusting the angle of the device by connecting the drive motor and the drive shaft is a conventional technique and will not be described in detail here. Furthermore, the first bracket is fixed to the mobile carriage by adhesive or screw connection.

[0059] An infrared thermal imager is also mounted on a mobile trolley, positioned below the tower and between the blade tip and the tower. The imager's lens is pointed towards the blade's turning direction to capture images of the blade tip. Specifically, the imager's lens is horizontally offset at an angle θ1 of 30°–75° towards the blade's turning side. Figure 7 and Figure 8 As shown, it can capture images of the blade tips over a wider area and with greater clarity. The infrared thermal imager's lens has an angle θ2 of 45° to 80° with the ground, allowing it to capture more images of the blade tips at an angle upwards, while avoiding the engine compartment and hub areas above, thus preventing the high temperatures in these areas from affecting the resolution of the infrared images of the blades.

[0060] In this embodiment, the angle between the lens of the infrared thermal imager and the ground is adjustable. Specifically, a second bracket 901 is fixed on the mobile trolley, and a second drive shaft 902 and a second drive motor 903 are connected to the second bracket. The infrared thermal imager is fixedly connected to the second drive shaft, and the second drive motor is connected to the second drive shaft and drives the second drive shaft to rotate, thereby adjusting the angle between the lens of the infrared thermal imager and the ground. Further, the second bracket is fixed to the mobile trolley by adhesive or screw connection.

[0061] The first and second spotlights are mounted on a mobile trolley. They emit different colors of light and are directed obliquely upwards towards the blades and tower, respectively. In low-light conditions such as nighttime or foggy weather, the first and second spotlights enhance the visibility of the blade tips and tower. In this embodiment, the mounting angles of the first and second spotlights are adjustable, and the angle adjustment mechanism also employs a drive motor and drive shaft. See [link to documentation]. Figure 2 Similar to the angle adjustment structure in camera devices and infrared thermal imagers, it will not be described here.

[0062] The data acquisition and transmission module is connected to the camera device and the infrared thermal imager to receive image data from the camera device and the infrared thermal imager.

[0063] The central processing unit (CPU) is connected to the data acquisition and transmission module via wired or wireless means. The CPU receives data from the module, and its image processing software analyzes the received image data. Based on object shape features and grayscale characteristics, it can identify the position of the tower and blade tips, thereby monitoring the tower clearance. The CPU can also send data such as the nacelle yaw angle to the data acquisition and transmission module for synchronization of the moving trolley's yaw with the nacelle.

[0064] In this embodiment, the control module can synchronize the yaw of the mobile trolley with the cabin, adjust the up and down pointing angle of the camera lens, adjust the angle between the infrared thermal imager lens and the ground, adjust the up and down pointing angle of the first and second lighting spotlights, and turn the first lighting spotlight, the second lighting spotlight and the infrared thermal imager on or off.

[0065] Specifically, the control module is connected to the data acquisition and transmission module. The control module is equipped with an inertial measurement module and a light sensor. The inertial measurement module is mounted on the mobile trolley and monitors the angle of rotation of the mobile trolley around the tower. The inertial measurement module transmits the monitored data to the control module and the data acquisition and transmission module. The data acquisition and transmission module transmits the data from the inertial measurement module to the central processing unit and transmits the nacelle yaw angle data to the control module. The control module is connected to the travel drive motor of the mobile trolley and controls the drive of the travel drive motor according to the angle of rotation of the mobile trolley around the tower and the nacelle yaw angle data, so that the mobile trolley is synchronized with the nacelle yaw, ensuring that the camera device and infrared thermal imager are always located below the tower and the blade tip.

[0066] The light sensor transmits the monitored ambient light intensity data to the control module and the data acquisition and transmission module. The control module controls the infrared thermal imager, the first illumination spotlight, and the second illumination spotlight to turn on or off based on the magnitude of the light intensity data.

[0067] In this embodiment, the control module is also connected to the first drive motor, the second drive motor, and the drive motor for adjusting the angles of the first and second lighting spotlights, thereby controlling and adjusting the up-and-down pointing angle of the camera lens, the angle between the lens of the infrared thermal imager and the ground, and the up-and-down pointing angles of the first and second lighting spotlights.

[0068] The monitoring method for the wind turbine tower clearance monitoring system provided by this invention includes the following steps:

[0069] S1. Select a circular track with an appropriate diameter. The diameter of the circular track should allow the camera device and the infrared thermal imager to be located below the tower and the blade tip, i.e. below the nacelle.

[0070] Install the circular track, mobile trolley, camera device, infrared thermal imager, first spotlight, second spotlight, data acquisition and transmission module and control module as required. Record the diameter R1 of the circular track, the angle β between the lens of the camera device and the ground, the angle θ1 of the lens of the infrared thermal imager in the horizontal direction towards the blade turning side, and the angle θ2 between the lens of the infrared thermal imager and the ground.

[0071] S2. The control module records the initial position of the moving trolley. When the nacelle yaws, the central processing unit transmits the yaw angle to the control module through the data acquisition and transmission module. The control module sends an action command to the travel drive motor based on the received yaw angle data. The travel drive motor drives the entire moving trolley to move towards the nacelle position after yaw. At the same time, the inertial measurement module monitors in real time and feeds back to the control module the angle by which the moving trolley has moved around the tower. When the moving angle of the moving trolley is the same as the nacelle yaw angle, the moving trolley stops moving. This ensures that after the nacelle yaws, the camera device and infrared thermal imager can still be located below the position between the tower and the blade tip.

[0072] S3. Based on the angle β between the camera lens and the ground, the angle θ1 of the infrared thermal imager lens in the horizontal direction towards the blade's inward side, the angle θ2 between the infrared thermal imager lens and the ground, the relative position parameters of the camera device and the infrared thermal imager on the moving trolley, and the structural dimensions of the camera device and the infrared thermal imager, the relative position and relative shooting angle of the camera lens and the infrared thermal imager lens in three-dimensional space can be determined.

[0073] S4. During the operation of the wind turbine, the camera device captures images of the tower and blade tips in real time and transmits the image data to the data acquisition and transmission module; the light sensor monitors the ambient light intensity data in real time and transmits it to the control module and the data acquisition and transmission module; the data acquisition and transmission module transmits the received image data and ambient light intensity data to the central processing unit.

[0074] S5. When the ambient light intensity is greater than the set threshold, the control module turns off the infrared thermal imager, the first illumination spotlight, and the second illumination spotlight. The image processing software of the central processing unit, based on the image of the tower and blade tip captured by the camera device, determines the position and relative distance of the tower and blade tip in the image according to the shape and grayscale characteristics of the tower and blade tip. Then, based on the ratio of the image size to the actual size, it calculates the minimum distance between the tower and the blade tip, i.e., the tower clearance value.

[0075] S6. When the ambient light intensity is less than or equal to the set threshold, the following two monitoring methods will be performed simultaneously:

[0076] S6.1 The control module turns on the infrared thermal imager, the first lighting spotlight and the second lighting spotlight. The camera device captures images of the tower and blade tips above in real time and transmits the image data to the central processing unit via the data acquisition and transmission module. The central processing unit calculates the tower clearance value according to step S5.

[0077] S6.2. While performing the monitoring method described in S6.1 above, an infrared thermal imager is used to capture images of the blade tips. The image data is then transmitted to the central processing unit via the data acquisition and transmission module. The image processing software of the central processing unit combines the blade tip images captured by the infrared thermal imager and the tower images captured by the camera device based on the relative positions and relative shooting angles of the lens of the camera device and the lens of the infrared thermal imager in three-dimensional space. The blade tips of the same blade at different positions during one revolution of the impeller are connected into a line, and this line is extended to the position of the tower in the composite image. The distance between the extended line and the tower in the composite image is the representation of the tower clearance value in the image. Based on the ratio of the image size to the actual size, the actual tower clearance value can be calculated.

[0078] During this process, the image trajectory of the blade tip captured by the camera device at the same wind speed when the ambient light intensity is greater than the set threshold is used as a correction reference for the extension line of the blade tip trajectory captured by the infrared thermal imager, thereby further improving the accuracy of drawing the extension line of the blade tip trajectory captured by the infrared thermal imager and the accuracy of the tower clearance value under this monitoring method.

[0079] S7. When any of the tower clearance values ​​calculated in S5, S6.1, and S6.2 above reach the set threshold, an early warning message will be issued.

Claims

1. A wind turbine tower clearance monitoring system characterized by: The wind turbine tower clearance monitoring system includes: A circular track is installed on the ground at the bottom of the tower and is coaxial with the tower. The upper surface of the circular track is a rough surface, and grooves are provided on both sides of the circular track. The mobile trolley includes a trolley body and running wheels connected to the bottom of the trolley body. The running wheels of the mobile trolley are in contact with the upper surface of the circular track. The running wheels are connected to a running drive motor, which drives the running wheels to move along the upper surface of the circular track. The bottom of the mobile trolley is equipped with two sets of anti-tilt wheels, which are respectively hung upside down in the grooves on both sides of the circular track. When the mobile trolley moves, the anti-tilt wheels move synchronously in the grooves. The camera device is mounted on a mobile trolley and located below the tower and the blade tip. The camera lens points upwards. When the blade passes the tower position, the camera device simultaneously captures the blade tip position and the tower position at the corresponding height. An infrared thermal imager is mounted on a mobile trolley and positioned below the tower and the blade tip. The lens of the infrared thermal imager points in the direction the blade is turning in. The angle θ1 of the lens in the horizontal direction towards the blade turning in is 30°~75°, and the angle θ2 between the lens and the ground is 45°~80°, capturing images of the blade tip. The first and second spotlights are both mounted on a mobile trolley and shine obliquely upwards toward the blades and the tower, respectively. The data acquisition and transmission module is connected to the camera device and the infrared thermal imager to receive image data from the camera device and the infrared thermal imager. The central processing unit is connected to the data acquisition and transmission module, receives data information sent by the data acquisition and transmission module, identifies the position of the tower and blade tip, and sends the nacelle yaw angle data information to the data acquisition and transmission module. The control module, connected to the data acquisition and transmission module, contains an inertial measurement module and a light sensor. The inertial measurement module is mounted on the moving trolley and monitors the angle of rotation of the trolley around the tower. The control module transmits the data from the inertial measurement module to the central processing unit via the data acquisition and transmission module and receives the yaw angle data of the nacelle. The control module is connected to the traveling drive motor of the moving trolley and controls the moving trolley to yaw synchronously with the nacelle. The light sensor transmits the monitored ambient light intensity data to the control module and the data acquisition and transmission module. The control module controls the infrared thermal imager, the first illumination spotlight, and the second illumination spotlight to turn on or off based on the magnitude of the light intensity data.

2. The wind turbine tower clearance monitoring system according to claim 1, characterized in that: The first and second spotlights use different colors of light.

3. The wind turbine tower clearance monitoring system according to claim 1, characterized in that: The installation angles of the first and second spotlights are adjustable.

4. The wind turbine tower clearance monitoring system according to claim 1, characterized in that: The up-down pointing angle of the lens of the camera device is adjustable.

5. The wind turbine tower clearance monitoring system according to claim 1, characterized in that: The angle between the lens of the infrared thermal imager and the ground is adjustable.

6. The wind turbine tower clearance monitoring system according to claim 1, characterized in that: The annular track is installed on the ground by a support frame, and one or more support frames are distributed at the bottom of the annular track; the annular track is embedded in the entrance step of the tower door, and the height of the upper surface of the annular track is flush with the height of the step into which it is embedded.

7. A monitoring method for a wind turbine tower clearance monitoring system according to any one of claims 1 to 6, characterized in that... Includes the following steps: S1. Select a suitable diameter circular track, and install the circular track, moving trolley, camera device, infrared thermal imager, first lighting spotlight, second lighting spotlight, data acquisition and transmission module and control module as required. Record the diameter R1 of the circular track, the angle β between the lens of the camera device and the ground, the angle θ1 of the lens of the infrared thermal imager in the horizontal direction towards the blade turning side, and the angle θ2 between the lens of the infrared thermal imager and the ground. S2. The control module records the initial position of the mobile trolley. When the nacelle yaws, the central processing unit transmits the yaw angle to the control module through the data acquisition and transmission module. The control module sends an action command to the travel drive motor based on the received yaw angle data. The travel drive motor drives the entire mobile trolley to move towards the nacelle position after yaw. At the same time, the inertial measurement module monitors in real time and feeds back to the control module the angle by which the mobile trolley has moved around the tower. When the moving angle of the mobile trolley is the same as the nacelle yaw angle, the mobile trolley stops moving. S3. Based on the angle β between the camera lens and the ground, the angle θ1 of the infrared thermal imager lens in the horizontal direction towards the blade's inward side, the angle θ2 between the infrared thermal imager lens and the ground, the relative position parameters of the camera device and the infrared thermal imager on the moving trolley, and the structural dimensions of the camera device and the infrared thermal imager, the relative position and relative shooting angle of the camera lens and the infrared thermal imager lens in three-dimensional space can be determined. S4. During the operation of the wind turbine, the camera device captures images of the tower and blade tips in real time and transmits the image data to the data acquisition and transmission module; the light sensor monitors the ambient light intensity data in real time and transmits it to the control module and the data acquisition and transmission module; the data acquisition and transmission module transmits the received image data and ambient light intensity data to the central processing unit. S5. When the ambient light intensity is greater than the set threshold, the control module turns off the infrared thermal imager, the first illumination spotlight, and the second illumination spotlight. The image processing software of the central processing unit, based on the image of the tower and blade tip captured by the camera device, determines the position and relative distance of the tower and blade tip in the image according to the shape and grayscale characteristics of the tower and blade tip. Then, based on the ratio of the image size to the actual size, it calculates the minimum distance between the tower and the blade tip, i.e., the tower clearance value. S6. When the ambient light intensity is less than or equal to the set threshold, the following two monitoring methods will be performed simultaneously: S6.1 The control module turns on the infrared thermal imager, the first lighting spotlight and the second lighting spotlight. The camera device captures images of the tower and blade tips above in real time and transmits the image data to the central processing unit via the data acquisition and transmission module. The central processing unit calculates the tower clearance value according to step S5. S6.

2. While performing the monitoring method described in S6.1 above, an infrared thermal imager is used to capture images of the blade tips. The image data is then transmitted to the central processing unit via the data acquisition and transmission module. The image processing software of the central processing unit combines the blade tip images captured by the infrared thermal imager and the tower images captured by the camera device based on the relative positions and relative shooting angles of the lens of the camera device and the lens of the infrared thermal imager in three-dimensional space. The blade tips of the same blade at different positions during one revolution of the impeller are connected into a line, and this line is extended to the position of the tower in the composite image. The distance between the extended line and the tower in the composite image is the representation of the tower clearance value in the image. Based on the ratio of the image size to the actual size, the actual tower clearance value can be calculated. S7. When any of the tower clearance values ​​calculated in S5, S6.1, and S6.2 above reach the set threshold, an early warning message will be issued.

8. The monitoring method of the wind turbine tower clearance monitoring system according to claim 7, characterized in that: In step S6.2, the trajectory of the blade tip image captured by the camera device at the same wind speed when the ambient light intensity is greater than a set threshold is used as a correction reference for the extension line of the blade tip trajectory captured by the infrared thermal imager.

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