Wind turbine blade clearance distance identification method and identification device, and protection system
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- BEIJING HUANENG XINRUI CONTROL TECH
- Filing Date
- 2025-08-22
- Publication Date
- 2026-06-26
Smart Images
Figure CN121273552B_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to the field of wind power generation technology, and in particular to a method, identification device, and protection system for identifying the clearance distance of wind turbine blades. Background Technology
[0002] With the continuous development of wind power generation technology, the size and power of wind turbine blades are constantly increasing. During wind turbine operation, the clearance distance between the turbine blades and the tower is crucial. If the clearance distance is too small, it may lead to collisions between the blades and the tower, causing serious equipment damage and safety accidents. However, existing wind turbine clearance monitoring and protection methods suffer from problems such as low accuracy, slow response speed, and insufficient reliability in monitoring clearance distance. Summary of the Invention
[0003] This disclosure aims to at least solve one of the problems existing in the prior art, and to provide a method, identification device, and protection system for identifying the clearance distance of wind turbine blades.
[0004] One aspect of this disclosure provides a method for identifying the clearance distance of wind turbine blades, the method comprising:
[0005] Using a millimeter-wave radar installed on the outer wall of the tower, multiple point cloud coordinates are obtained when the tip of the wind turbine blade passes through the scanning range of the millimeter-wave radar.
[0006] Based on the multiple point cloud coordinates and the geometric position of the millimeter-wave radar on the tower, the trajectory of the blade tip when it passes through the scanning range of the millimeter-wave radar is determined.
[0007] Based on the trajectory of movement, the clearance distance between the blade tip and the tower is determined.
[0008] Optionally, determining the trajectory of the blade tip as it passes through the scanning range of the millimeter-wave radar, based on the multiple point cloud coordinates and the geometric position of the millimeter-wave radar on the tower, includes:
[0009] The multiple point cloud coordinates are respectively converted into target point cloud coordinates in the translation coordinate system of the tangent of the outer wall of the tower; wherein, in the vertical direction of the ground, the offset of the translation coordinate system relative to the millimeter-wave radar coordinate system in which the multiple point cloud coordinates are located is 0; in the vertical direction of the outer wall of the tower, the offset of the translation coordinate system relative to the millimeter-wave radar coordinate system is y0; in the direction parallel to the tangent of the outer wall of the tower, the offset of the translation coordinate system relative to the millimeter-wave radar coordinate system is z0.
[0010] Based on the target point cloud coordinates, the trajectory point cloud coordinates corresponding to each scanning cycle of the millimeter-wave radar are selected; wherein, the coordinate value of the trajectory point cloud coordinates in the direction perpendicular to the ground is 0, and the coordinate value of the trajectory point cloud coordinates in the direction parallel to the tangent of the outer wall of the tower is z0.
[0011] Optionally, determining the clearance distance between the blade tip and the tower based on the movement trajectory includes:
[0012] The minimum coordinate value of each trajectory point cloud coordinate in the vertical direction of the outer wall of the tower is taken as the minimum clearance distance value of the blade tip.
[0013] Optionally, the number of millimeter-wave radars installed on the outer wall of the tower is multiple, and the scanning range of the multiple millimeter-wave radars covers a 360-degree area surrounding the tower; and,
[0014] The center height of each millimeter-wave radar is greater than the tip height of the wind turbine blade when it is perpendicular to the ground, and the difference between the center height and the tip height is within the range of 0.5 meters to 1 meter. At the same time, the center height of each millimeter-wave radar is consistent.
[0015] Optionally, the number of millimeter-wave radars is four, and each millimeter-wave radar covers a 90-degree area surrounding the tower.
[0016] Optionally, the identification method further includes:
[0017] If the clearance between the blade tip and the tower is less than the safety threshold, an alarm signal will be issued and protective measures will be activated.
[0018] Optionally, the startup protection measures include:
[0019] When the minimum clearance distance at the blade tip is less than the safety threshold and greater than the safety warning value, and the safety warning value is less than the safety threshold, the low clearance normal feathering mode is activated. If the pitch angle of the wind turbine is less than the preset limit and the generator speed is greater than the preset ratio of its rated speed, then the first blade recovery rate is superimposed on the minimum pitch angle limit of the wind turbine to adjust the wind turbine blades to feathering state; otherwise, the original design power of the wind turbine is executed.
[0020] Optionally, the startup protection measures further include:
[0021] When the minimum clearance distance at the blade tip is less than the minimum safety limit, and the minimum safety limit is less than the safety warning value, the low clearance fault shutdown mode is activated, and the propeller is retracted and the machine is stopped according to the preset pitch angle interpolation point and the preset pitch rate.
[0022] When the minimum clearance distance value at the blade tip is less than the safety warning value but greater than or equal to the minimum safety limit, the low emergency feathering mode is activated, and a second retardation rate is superimposed on the minimum pitch angle limit of the wind turbine to adjust the wind turbine blades to a feathering state.
[0023] Another aspect of this disclosure provides a wind turbine blade clearance distance identification device, the identification device comprising:
[0024] The acquisition module is used to acquire multiple point cloud coordinates of the blade tip of the wind turbine when it passes through the scanning range of the millimeter-wave radar installed on the outer wall of the tower.
[0025] The trajectory determination module is used to determine the movement trajectory of the blade tip when it passes through the scanning range of the millimeter-wave radar, based on the multiple point cloud coordinates and the geometric position of the millimeter-wave radar on the tower.
[0026] The clearance distance determination module is used to determine the clearance distance between the blade tip and the tower based on the movement trajectory.
[0027] Optionally, the identification device further includes:
[0028] The alarm module is used to issue an alarm signal and activate protective measures when the clearance distance between the blade tip and the tower is less than a safety threshold.
[0029] Another aspect of this disclosure provides a wind turbine blade clearance distance protection system, the protection system including a clearance monitoring device and a central control system; the clearance monitoring device is communicatively connected to the central control system.
[0030] The clearance monitoring device is used to acquire multiple point cloud coordinates of the blade tip when it passes through the scanning range of the millimeter-wave radar installed on the outer wall of the tower; based on the multiple point cloud coordinates and the geometric position of the millimeter-wave radar on the tower, it determines the trajectory of the blade tip when it passes through the scanning range of the millimeter-wave radar; based on the trajectory, it determines the clearance distance between the blade tip and the tower, and transmits the clearance distance to the central control system.
[0031] The central control system is used to receive the clearance distance, issue an alarm signal and activate protective measures when the clearance distance is less than a safety threshold.
[0032] Compared with the prior art, this disclosure can monitor the clearance distance of wind turbines of different types and sizes in real time with high accuracy and fast response speed, and has a wide range of application prospects. It can also take corresponding protective measures in time when the clearance distance is too small, effectively preventing the occurrence of blade-to-tower collision accidents, and improving the safety and reliability of wind turbine operation. Attached Figure Description
[0033] One or more embodiments are illustrated by way of example with the corresponding pictures in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.
[0034] Figure 1 A flowchart of a method for identifying the clearance distance of wind turbine blades provided in one embodiment of this disclosure;
[0035] Figure 2 A schematic diagram of the installation location of a millimeter-wave radar provided for another embodiment of this disclosure;
[0036] Figure 3 A flowchart illustrating a clearance distance protection measure provided in another embodiment of this disclosure;
[0037] Figure 4 This is a schematic diagram of a wind turbine blade clearance distance identification device provided for another embodiment of the present disclosure. Detailed Implementation
[0038] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the various embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the various embodiments of this disclosure to facilitate a better understanding of the disclosure. However, the technical solutions claimed in this disclosure can be implemented even without these technical details and with various variations and modifications based on the following embodiments. The division of the various embodiments below is for ease of description and should not constitute any limitation on the specific implementation of this disclosure. The various embodiments can be combined with and referenced by each other without contradiction.
[0039] One embodiment of this disclosure relates to a method for identifying the clearance distance of wind turbine blades, the process of which is as follows: Figure 1 As shown, it includes steps S110 to S130.
[0040] Step S110: Using a millimeter-wave radar installed on the outer wall of the tower, obtain multiple point cloud coordinates when the tip of the wind turbine blade passes through the scanning range of the millimeter-wave radar.
[0041] Specifically, this embodiment uses millimeter-wave radar ranging technology, utilizing millimeter-wave radar installed on the outer wall of the wind turbine tower to monitor the clearance distance between the blade tip of the wind turbine and the tower in real time.
[0042] For example, multiple millimeter-wave radars are installed on the outer wall of the tower, and the scanning range of the multiple millimeter-wave radars covers a 360-degree area surrounding the tower. Furthermore, the center height of each millimeter-wave radar is greater than the tip height of the wind turbine blade when it is perpendicular to the ground, and the difference between the center height and the tip height is within the range of 0.5 meters to 1 meter. At the same time, the center height of each millimeter-wave radar is consistent.
[0043] Specifically, combined Figure 2 When the blades are perpendicular to the ground, the millimeter-wave radar can be positioned on the outer wall of the tower, above the blade tip height. The difference between the center height of the millimeter-wave radar and the blade tip height should be within 0.5 to 1 meter, allowing the radar to detect the clearance distance between the blade tip and the tower in real time. Simultaneously, the scanning range of each millimeter-wave radar covers a 360-degree area surrounding the tower, and their center heights remain consistent, ensuring that all radars are on the same horizontal plane, forming a 360-degree all-around horizontal monitoring plane. This monitoring plane allows for real-time, comprehensive monitoring of the blade's trajectory and clearance distance, enabling precise control of blade dynamics regardless of changes in the yaw angle of the nacelle or blade.
[0044] Preferably, there are four millimeter-wave radars, each covering a 90-degree area surrounding the tower. Ultra-wide-angle millimeter-wave radars can be used to overcome the limitations of traditional millimeter-wave radars in terms of detection range, angular coverage, and environmental adaptability.
[0045] Step S120: Based on multiple point cloud coordinates and the geometric position of the millimeter-wave radar on the tower, determine the trajectory of the blade tip when it passes through the scanning range of the millimeter-wave radar.
[0046] Specifically, step S120 can perform coordinate transformation on multiple point cloud coordinates based on the geometric position of the millimeter-wave radar on the tower, thereby obtaining the movement trajectory of the blade tip when it passes through the scanning range of the millimeter-wave radar.
[0047] For example, step S120 includes: converting multiple point cloud coordinates into target point cloud coordinates in a translation coordinate system of the tangent of the tower's outer wall. Specifically, in the vertical direction relative to the millimeter-wave radar coordinate system containing the multiple point cloud coordinates, the offset of the translation coordinate system is 0. In the vertical direction relative to the millimeter-wave radar coordinate system, the offset of the translation coordinate system is y0. In the direction parallel to the tangent of the tower's outer wall, the offset of the translation coordinate system is z0. Based on the target point cloud coordinates, the trajectory point cloud coordinates corresponding to each scanning cycle of the millimeter-wave radar are selected. Specifically, the coordinate value of the trajectory point cloud coordinates in the vertical direction is 0, and the coordinate value in the direction parallel to the tangent of the tower's outer wall is z0.
[0048] Specifically, combining the data model of the wind turbine tower outer wall and the geometric position of the millimeter-wave radar on the tower outer wall, the translational coordinate system of the tower outer wall tangent within the ±45 degree scanning angle range of the millimeter-wave radar can be represented as (0, y0, z0). Let the vertical direction of the earth be denoted as the x-direction, the vertical direction of the tower outer wall as the y-direction, and the direction parallel to the tower outer wall tangent as the z-direction. Assuming the point cloud coordinates acquired by the millimeter-wave radar are (x1, y1, z1), the target point cloud coordinates obtained by transforming these coordinates can be represented as (x1, y1+y0, z1+z0).
[0049] Since the number of point cloud coordinates collected by the millimeter-wave radar increases when the blade tip passes through its scanning range, the number of point cloud coordinates collected by the millimeter-wave radar can be used to determine whether the blade tip has passed through its scanning range. For example, if the number of point cloud coordinates collected by a millimeter-wave radar in one scan is greater than a set value, such as 30,000, then the radar's detection is considered valid.
[0050] Assuming the millimeter-wave radar has a scanning period of 50ms, the coordinates of target points within the same 50ms acquisition interval are statistically analyzed. These points have a coordinate value of 0 in the x-direction (vertical to the ground) and a coordinate value of z0 in the z-direction (parallel to the tangent on the outer wall of the tower). These statistically analyzed target point cloud coordinates can then be used as the coordinates of each trajectory point cloud. The scanning period of the millimeter-wave radar can be set between 50ms and 100ms to avoid reducing detection accuracy due to excessively short scanning periods.
[0051] Step S130: Determine the clearance distance between the blade tip and the tower based on the movement trajectory.
[0052] Specifically, step S130 can use the coordinate values of the trajectory point cloud corresponding to the movement trajectory in the y direction, i.e., the vertical direction of the outer wall of the tower, to determine the clearance distance between the blade tip and the tower.
[0053] For example, step S130 includes: taking the minimum coordinate value of each trajectory point cloud coordinate in the vertical direction of the outer wall of the tower as the minimum clearance distance value of the blade tip.
[0054] Specifically, the coordinates of each trajectory point cloud are marked as (0, yc, z0), where yc represents the coordinate value of the y direction in the trajectory point cloud coordinates, which is the vertical direction of the outer wall of the tower. Then, in step S130, the minimum value of yc can be used as the minimum clearance distance value of the blade tip.
[0055] The wind turbine blade clearance distance identification method provided in this disclosure, compared with the prior art, can monitor the clearance distance of wind turbines of different types and sizes in real time, with high accuracy and fast response speed, and has broad application prospects.
[0056] For example, the wind turbine blade clearance distance identification method further includes: if the clearance distance between the blade tip and the tower is less than a safety threshold, an alarm signal is issued and protective measures are activated.
[0057] Specifically, the specific value of the safety threshold can be determined according to actual needs, and this implementation method does not limit it. The alarm signal can take any one or more forms such as sound, light, and vibration, and those skilled in the art can select and set it according to actual needs. The actuator for the protection measures can be the pitch system of the wind turbine. Based on the different relationships between the clearance distance and the safety threshold, the pitch system can adjust the wind turbine's operating state through different clearance protection modes to achieve clearance distance protection, such as normal clearance mode, normal feathering mode for low clearance, fault shutdown mode for excessively low clearance, emergency feathering mode for low clearance, and safe clearance mode.
[0058] By issuing an alarm signal and activating protective measures when the clearance between the blade tip and the tower is less than the safety threshold, appropriate protective measures can be taken in a timely manner when the clearance is too small, effectively preventing blade-to-tower collision accidents and improving the safety and reliability of wind turbine operation.
[0059] For example, the activation of protection measures includes: when the minimum clearance distance between the blade tips is less than the safety threshold and greater than the safety warning value, and the safety warning value is less than the safety threshold, the low clearance normal feathering mode is activated; if the pitch angle of the wind turbine is less than the preset limit and the generator speed is greater than the preset ratio of its rated speed, then the first blade recovery rate is superimposed on the minimum pitch angle limit of the wind turbine to adjust the wind turbine blades to the feathering state; otherwise, the original design power of the wind turbine is executed.
[0060] For example, the activation protection measures also include: when the minimum clearance distance at the blade tip is less than the minimum safety limit, and the minimum safety limit is less than the safety warning value, activating the low clearance fault shutdown mode, and retracting the blades to shut down according to the preset pitch angle interpolation point and preset pitch rate. When the minimum clearance distance at the blade tip is less than the safety warning value but greater than or equal to the minimum safety limit, activating the low clearance emergency feathering mode, superimposing a second feathering rate on the minimum pitch angle limit of the wind turbine, and adjusting the wind turbine blades to a feathered state.
[0061] Specifically, the minimum safety limit is less than the safety warning value, and the safety warning value is less than the safety threshold. For example, the minimum safety limit can be set to 4m, the safety warning value can be set to 5m, and the safety threshold can be set to 6m. Based on the relationship between the minimum clearance distance to the blade tip and the minimum safety limit, safety warning value, and safety threshold, different protection measures can be taken through different clearance protection modes.
[0062] For example, combined Figure 3After the wind turbine blade clearance distance identification process begins, it first determines whether clearance control is enabled. If not, the original design power of the wind turbine is executed. If so, it determines whether the interface clearance safety mode is enabled. If the interface clearance safety mode is enabled, the safe clearance power of the wind turbine is executed; otherwise, it determines whether the clearance data is valid. If the clearance data is invalid, the safe clearance power of the wind turbine is executed. If the clearance data is valid, it combines the clearance radar measurement value (i.e., the minimum tip clearance distance value obtained through the wind turbine blade clearance distance identification method) and the data validity flag to determine which clearance protection mode to activate. Assuming the minimum safety limit is set to 4m, the safety warning value is set to 5m, and the safety threshold is set to 6m, based on the relationship between the clearance value (i.e., the minimum tip clearance distance value) and the minimum safety limit, safety warning value, and safety threshold, three cases can be identified.
[0063] In the first case (Case 1), if the clearance value is greater than the safety threshold (i.e., clearance value > 6m), the safety clearance mode is activated, and the original design power of the fan is executed.
[0064] In the second case (Case 2), the clearance value is greater than the safety warning value but less than the safety threshold, i.e., 5m < clearance value < 6m. In this case, the low clearance normal feathering mode is activated. It is determined whether the pitch angle is less than 10 degrees and the generator speed is greater than 0.8 times its rated speed, i.e., generator speed > 0.8 times the rated speed. If the conditions are met, the first pitch recovery rate is added to the minimum pitch angle limit of the wind turbine, i.e., minimum pitch angle limit plus pitch recovery rate 1, to adjust the wind turbine blades to feathering state. Otherwise, the original design power of the wind turbine is executed.
[0065] In the third case (Case 3), the clearance value is less than the safety threshold, i.e., clearance value < 5m. In this case, it is determined whether the clearance value is less than 4m, i.e., clearance value < 4m and pitch angle < 10 degrees, and generator speed > 0.8 rated speed. If so, the low clearance fault shutdown mode is activated, and the turbine is stopped by retracting the pitch according to the preset pitch angle interpolation point and preset pitch rate to achieve emergency shutdown. Otherwise, the low clearance emergency feathering mode is activated, and a second retracting rate is superimposed on the minimum pitch angle limit of the wind turbine, i.e., minimum pitch angle limit superimposed on retracting rate 2, to adjust the wind turbine blades to feathering state.
[0066] Taking a 7.5MW wind turbine as an example, different return propeller rates and target angles are set under different airspace protection modes.
[0067] (1) Low clearance normal feathering mode: When the clearance value is in the range of [5.5m, 6.0m], the minimum pitch angle limit is increased by 0.5 degrees per second; when the clearance value is in the range of [5.0m, 5.5m], the minimum pitch angle limit is increased by 1.0 degrees per second, for a total of 3 seconds. After the additional value is maintained for 20 seconds, it decreases by 0.25 degrees per second until it reaches 0 degrees.
[0068] (2) Low air clearance fault shutdown mode: The wind turbine enters the emergency shutdown state and stops the turbine by retracting the pitch according to the preset pitch angle and pitch rate interpolation table. The pitch angle interpolation point (unit: deg) is [-1, 40, 89, 95] and the pitch rate (unit: deg / s) is [4, 1, 3.5, 0.8].
[0069] (3) Low clearance emergency feathering mode: The minimum pitch angle limit is increased by 2.5 degrees per second for a total of 4 seconds. After the additional value is maintained for 20 seconds, it decreases by 0.625 degrees per second until it reaches 0 degrees.
[0070] (4) No airspace protection mode / normal airspace mode: When the wind turbine is generating electricity, pitch control is performed according to the preset power and pitch angle interpolation table of the corresponding mode. The power interpolation point (unit is kW) is [0,3510,4510,6010,7010,7500], and the pitch angle interpolation point (unit is deg) is [-0.5,-0.5,2.5,3,4,5].
[0071] (5) Safety clearance mode: When the wind turbine is generating electricity, the pitch angle is controlled according to the preset power and pitch angle interpolation table in this mode. The power interpolation point (unit is kW) is [0,2010,2510,3510,5010,6510,7500], and the pitch angle interpolation point (unit is deg) is [0.5,0.5,2.5,4,5,6,7.5,8.5].
[0072] Another embodiment of this disclosure relates to a wind turbine blade clearance distance identification device, such as... Figure 4 As shown, it includes an acquisition module 410, a trajectory determination module 420, and a clearance distance determination module 430.
[0073] The acquisition module 410 is used to acquire multiple point cloud coordinates when the tip of the wind turbine blade passes through the scanning range of the millimeter-wave radar installed on the outer wall of the tower.
[0074] The trajectory determination module 420 is used to determine the movement trajectory of the blade tip when it passes through the scanning range of the millimeter-wave radar, based on multiple point cloud coordinates and the geometric position of the millimeter-wave radar on the tower.
[0075] The clearance distance determination module 430 is used to determine the clearance distance between the blade tip and the tower based on the movement trajectory.
[0076] For example, the wind turbine blade clearance distance identification device also includes an alarm module. The alarm module is used to issue an alarm signal and activate protective measures when the clearance distance between the blade tip and the tower is less than a safety threshold.
[0077] For a detailed implementation method of the wind turbine blade clearance distance identification device provided in this disclosure, please refer to the wind turbine blade clearance distance identification method provided in this disclosure, which will not be repeated here.
[0078] The wind turbine blade clearance distance identification device provided in this disclosure, compared with the prior art, can monitor the clearance distance of wind turbines of different types and sizes in real time with high accuracy and fast response speed. It has a wide range of application prospects and can also take corresponding protective measures in time when the clearance distance is too small, effectively preventing the occurrence of blade-to-tower collision accidents and improving the safety and reliability of wind turbine operation.
[0079] Another embodiment of this disclosure relates to a wind turbine blade clearance distance protection system, including a clearance monitoring device and a central control system, wherein the clearance monitoring device is communicatively connected to the central control system.
[0080] The clearance monitoring device uses a millimeter-wave radar installed on the outer wall of the tower to acquire multiple point cloud coordinates when the tip of the wind turbine blade passes through the scanning range of the millimeter-wave radar; based on the multiple point cloud coordinates and the geometric position of the millimeter-wave radar on the tower, it determines the movement trajectory of the blade tip when it passes through the scanning range of the millimeter-wave radar; based on the movement trajectory, it determines the clearance distance between the blade tip and the tower, and transmits the clearance distance to the central control system.
[0081] The central control system receives the clearance distance and issues an alarm signal and activates protective measures when the clearance distance is less than the safety threshold.
[0082] For a detailed implementation method of the wind turbine blade clearance distance protection system provided in this disclosure, please refer to the wind turbine blade clearance distance identification method provided in this disclosure, which will not be repeated here.
[0083] The wind turbine blade clearance distance protection system provided in this disclosure, compared with the prior art, can monitor the clearance distance of wind turbines of different types and sizes in real time with high accuracy and fast response speed. It has a wide range of application prospects and can also take corresponding protective measures in time when the clearance distance is too small, effectively preventing the occurrence of blade-to-tower collision accidents and improving the safety and reliability of wind turbine operation.
[0084] Those skilled in the art will understand that the above embodiments are specific implementations of this disclosure, and in practical applications, various changes can be made to them in form and detail without departing from the spirit and scope of this disclosure.
Claims
1. A method for identifying the clearance distance of wind turbine blades, characterized in that, The identification method includes: Using a millimeter-wave radar installed on the outer wall of the tower, multiple point cloud coordinates are obtained when the tip of the wind turbine blade passes through the scanning range of the millimeter-wave radar. Based on the multiple point cloud coordinates and the geometric position of the millimeter-wave radar on the tower, the trajectory of the blade tip when it passes through the scanning range of the millimeter-wave radar is determined. Based on the trajectory of movement, the clearance distance between the blade tip and the tower is determined; The determination of the movement trajectory of the blade tip as it passes through the scanning range of the millimeter-wave radar, based on the multiple point cloud coordinates and the geometric position of the millimeter-wave radar on the tower, includes: The multiple point cloud coordinates are respectively converted into target point cloud coordinates in the translation coordinate system of the tangent of the outer wall of the tower; wherein, in the vertical direction of the ground, the offset of the translation coordinate system relative to the millimeter-wave radar coordinate system in which the multiple point cloud coordinates are located is 0; in the vertical direction of the outer wall of the tower, the offset of the translation coordinate system relative to the millimeter-wave radar coordinate system is y0; in the direction parallel to the tangent of the outer wall of the tower, the offset of the translation coordinate system relative to the millimeter-wave radar coordinate system is z0. Based on the target point cloud coordinates, the trajectory point cloud coordinates corresponding to each scanning cycle of the millimeter-wave radar are selected; wherein, the coordinate value of the trajectory point cloud coordinates in the vertical direction of the ground is 0, and the coordinate value of the trajectory point cloud coordinates in the direction parallel to the tangent of the outer wall of the tower is z0. Multiple millimeter-wave radars are installed on the outer wall of the tower, and the scanning range of these multiple millimeter-wave radars covers a 360-degree area surrounding the tower; and... The center height of each millimeter-wave radar is greater than the tip height of the wind turbine blade when it is perpendicular to the ground, and the difference between the center height and the tip height is within the range of 0.5 meters to 1 meter. At the same time, the center height of each millimeter-wave radar is consistent. The identification method further includes: If the clearance between the blade tip and the tower is less than the safety threshold, an alarm signal will be issued and protective measures will be activated. The startup protection measures include: When the minimum clearance distance between blade tips is less than the safety threshold and greater than the safety warning value, and the safety warning value is less than the safety threshold, the low clearance normal feathering mode is activated. If the pitch angle of the wind turbine is less than the preset limit and the generator speed is greater than the preset ratio of its rated speed, the first blade recovery rate is superimposed on the minimum pitch angle limit of the wind turbine to adjust the wind turbine blades to feathering state; otherwise, the original design power of the wind turbine is executed. The startup protection measures also include: When the minimum clearance distance at the blade tip is less than the minimum safety limit, and the minimum safety limit is less than the safety warning value, the low clearance fault shutdown mode is activated, and the propeller is retracted and the machine is stopped according to the preset pitch angle interpolation point and the preset pitch rate. When the minimum clearance distance value at the blade tip is less than the safety warning value but greater than or equal to the minimum safety limit, the low emergency feathering mode is activated, and a second retardation rate is superimposed on the minimum pitch angle limit of the wind turbine to adjust the wind turbine blades to a feathering state.
2. The identification method according to claim 1, characterized in that, Determining the clearance distance between the blade tip and the tower based on the movement trajectory includes: The minimum coordinate value of each trajectory point cloud coordinate in the vertical direction of the outer wall of the tower is taken as the minimum clearance distance value of the blade tip.
3. The identification method according to claim 1, characterized in that, The number of millimeter-wave radars is four, and each millimeter-wave radar covers a 90-degree area surrounding the tower.
4. A wind turbine blade clearance distance identification device, characterized in that, The identification device includes: The acquisition module is used to acquire multiple point cloud coordinates of the blade tip of the wind turbine when it passes through the scanning range of the millimeter-wave radar installed on the outer wall of the tower. The trajectory determination module is used to determine the movement trajectory of the blade tip when it passes through the scanning range of the millimeter-wave radar, based on the multiple point cloud coordinates and the geometric position of the millimeter-wave radar on the tower. The clearance distance determination module is used to determine the clearance distance between the blade tip and the tower based on the movement trajectory; The determination of the movement trajectory of the blade tip as it passes through the scanning range of the millimeter-wave radar, based on the multiple point cloud coordinates and the geometric position of the millimeter-wave radar on the tower, includes: The multiple point cloud coordinates are respectively converted into target point cloud coordinates in the translation coordinate system of the tangent of the outer wall of the tower; wherein, in the vertical direction of the ground, the offset of the translation coordinate system relative to the millimeter-wave radar coordinate system in which the multiple point cloud coordinates are located is 0; in the vertical direction of the outer wall of the tower, the offset of the translation coordinate system relative to the millimeter-wave radar coordinate system is y0; in the direction parallel to the tangent of the outer wall of the tower, the offset of the translation coordinate system relative to the millimeter-wave radar coordinate system is z0. Based on the target point cloud coordinates, the trajectory point cloud coordinates corresponding to each scanning cycle of the millimeter-wave radar are selected; wherein, the coordinate value of the trajectory point cloud coordinates in the vertical direction of the ground is 0, and the coordinate value of the trajectory point cloud coordinates in the direction parallel to the tangent of the outer wall of the tower is z0. Multiple millimeter-wave radars are installed on the outer wall of the tower, and the scanning range of these multiple millimeter-wave radars covers a 360-degree area surrounding the tower; and... The center height of each millimeter-wave radar is greater than the tip height of the wind turbine blade when it is perpendicular to the ground, and the difference between the center height and the tip height is within the range of 0.5 meters to 1 meter. At the same time, the center height of each millimeter-wave radar is consistent. The identification device further includes: An alarm module is used to issue an alarm signal and activate protective measures when the clearance distance between the blade tip and the tower is less than a safety threshold. The startup protection measures include: When the minimum clearance distance between blade tips is less than the safety threshold and greater than the safety warning value, and the safety warning value is less than the safety threshold, the low clearance normal feathering mode is activated. If the pitch angle of the wind turbine is less than the preset limit and the generator speed is greater than the preset ratio of its rated speed, the first blade recovery rate is superimposed on the minimum pitch angle limit of the wind turbine to adjust the wind turbine blades to feathering state; otherwise, the original design power of the wind turbine is executed. The startup protection measures also include: When the minimum clearance distance at the blade tip is less than the minimum safety limit, and the minimum safety limit is less than the safety warning value, the low clearance fault shutdown mode is activated, and the propeller is retracted and the machine is stopped according to the preset pitch angle interpolation point and the preset pitch rate. When the minimum clearance distance value at the blade tip is less than the safety warning value but greater than or equal to the minimum safety limit, the low emergency feathering mode is activated, and a second retardation rate is superimposed on the minimum pitch angle limit of the wind turbine to adjust the wind turbine blades to a feathering state.
5. A wind turbine blade clearance distance protection system, characterized in that, The protection system includes an airspace monitoring device and a central control system; the airspace monitoring device is communicatively connected to the central control system. The clearance monitoring device is used to acquire multiple point cloud coordinates of the blade tip when it passes through the scanning range of the millimeter-wave radar installed on the outer wall of the tower; based on the multiple point cloud coordinates and the geometric position of the millimeter-wave radar on the tower, it determines the trajectory of the blade tip when it passes through the scanning range of the millimeter-wave radar; based on the trajectory, it determines the clearance distance between the blade tip and the tower, and transmits the clearance distance to the central control system. The central control system is used to receive the clearance distance, issue an alarm signal and activate protective measures when the clearance distance is less than a safety threshold. The determination of the movement trajectory of the blade tip as it passes through the scanning range of the millimeter-wave radar, based on the multiple point cloud coordinates and the geometric position of the millimeter-wave radar on the tower, includes: The multiple point cloud coordinates are respectively converted into target point cloud coordinates in the translation coordinate system of the tangent of the outer wall of the tower; wherein, in the vertical direction of the ground, the offset of the translation coordinate system relative to the millimeter-wave radar coordinate system in which the multiple point cloud coordinates are located is 0; in the vertical direction of the outer wall of the tower, the offset of the translation coordinate system relative to the millimeter-wave radar coordinate system is y0; in the direction parallel to the tangent of the outer wall of the tower, the offset of the translation coordinate system relative to the millimeter-wave radar coordinate system is z0. Based on the target point cloud coordinates, the trajectory point cloud coordinates corresponding to each scanning cycle of the millimeter-wave radar are selected; wherein, the coordinate value of the trajectory point cloud coordinates in the vertical direction of the ground is 0, and the coordinate value of the trajectory point cloud coordinates in the direction parallel to the tangent of the outer wall of the tower is z0. Multiple millimeter-wave radars are installed on the outer wall of the tower, and the scanning range of these multiple millimeter-wave radars covers a 360-degree area surrounding the tower; and... The center height of each millimeter-wave radar is greater than the tip height of the wind turbine blade when it is perpendicular to the ground, and the difference between the center height and the tip height is within the range of 0.5 meters to 1 meter. At the same time, the center height of each millimeter-wave radar is consistent. The startup protection measures include: When the minimum clearance distance between blade tips is less than the safety threshold and greater than the safety warning value, and the safety warning value is less than the safety threshold, the low clearance normal feathering mode is activated. If the pitch angle of the wind turbine is less than the preset limit and the generator speed is greater than the preset ratio of its rated speed, the first blade recovery rate is superimposed on the minimum pitch angle limit of the wind turbine to adjust the wind turbine blades to feathering state; otherwise, the original design power of the wind turbine is executed. The startup protection measures also include: When the minimum clearance distance at the blade tip is less than the minimum safety limit, and the minimum safety limit is less than the safety warning value, the low clearance fault shutdown mode is activated, and the propeller is retracted and the machine is stopped according to the preset pitch angle interpolation point and the preset pitch rate. When the minimum clearance distance value at the blade tip is less than the safety warning value but greater than or equal to the minimum safety limit, the low emergency feathering mode is activated, and a second retardation rate is superimposed on the minimum pitch angle limit of the wind turbine to adjust the wind turbine blades to a feathering state.