Blade clearance distance monitoring system and blade clearance distance monitoring method

Abstract

An embodiment of the present invention discloses a blade clearance distance monitoring system and a blade clearance distance monitoring method, which are used to measure the clearance distance using a radar probe. Because the radar probe has good weather resistance, it has relatively high anti-interference performance. An embodiment of the present invention provides a clearance distance monitoring system, which includes multiple radar probes, a controller, a tower, and a wind turbine. The wind turbine includes blades. The multiple radar probes and the controller are arranged on the tower, the controller is connected to the multiple radar probes, and the wind turbine is arranged at the top of the tower. The distance between the multiple radar probes and the top of the tower is greater than a first distance and less than a second distance, wherein the first distance is half the length of the blade, and the second distance is half the distance between the tip of the blade and the bottom of the tower plus half the length of the blade.

Description

Technical Field

[0001] The present invention relates to the technical field of wind turbines, and in particular to a blade clearance distance monitoring system and a blade clearance distance monitoring method. Background Art

[0002] For wind power generation, some areas mainly rely on low wind speed power generation. In order to capture the wind kinetic energy as much as possible in low wind speed areas, high towers and long blades are standard for low wind speed wind turbines.

[0003] As wind turbines have grown in size, generating power at over 7MW today, up from 1MW years ago, their structure has undergone significant changes, with blade length increasing from approximately 20 meters to over 80 meters. This increase in blade length also increases the amount of deformation that occurs during operation. To ensure the safe operation of wind turbines, a minimum safe distance must be maintained between the blades and the tower after blade deformation, known as the minimum clearance distance.

[0004] In order to ensure the wind capture efficiency of wind turbines as much as possible, the blades need to bear the wind force to the maximum extent under safe conditions. Therefore, monitoring the clearance distance between the blades can ensure the safe operation of the blades and the wind turbine, and also provide effective support for the power generation of the wind turbine.

[0005] Currently, there is no effective means of monitoring clearance. Some manufacturers install laser ranging equipment on the top of the wind turbine nacelle to monitor the blade clearance, but the actual monitoring effect is poor and cannot effectively monitor the blade clearance distance. At the same time, the laser ranging equipment will be affected by extreme weather environments such as rain, fog, dust, haze, and low temperature, which will render the monitoring function ineffective. Especially in strong winds (typhoons), the operation of wind turbines must strictly monitor the blade clearance, but this is also the time when the laser ranging equipment is most likely to fail. This will pose a huge risk to the wind turbine generator set, and in severe cases, it will cause the blades to collide with the tower, causing the wind turbine generator set to collapse. Summary of the Invention

[0006] The embodiments of the present invention provide a blade clearance distance monitoring system and a blade clearance distance monitoring method for measuring the clearance distance using a radar probe. Because the radar probe is weather-resistant and highly resistant to environmental interference, it can operate normally in adverse weather conditions such as rain, fog, sand, dust, and strong winds, thereby making the blade clearance monitoring system more reliable.

[0007] A first aspect of the present invention provides a blade clearance distance monitoring system, the blade clearance distance monitoring system comprising a plurality of radar probes, a controller, a tower and a wind turbine, the wind turbine comprising blades;

[0008] The multiple radar probes and the controller are arranged on the tower, the controller is connected to the multiple radar probes, and the wind turbine is arranged on the top of the tower;

[0009] The distance between the multiple radar probes and the top of the tower is greater than a first distance and less than a second distance, wherein the first distance is half of the length of the blade, and the second distance is half of the distance between the tip of the blade and the bottom of the tower plus half of the length of the blade.

[0010] Optionally, in some embodiments of the present invention, the radar probe includes a millimeter wave radar.

[0011] Optionally, in some embodiments of the present invention, the plurality of radar probes include three radar probes, and the three radar probes are arranged at three equally divided points of a section circle at the same height of the tower; or,

[0012] The multiple radar probes include four radar probes, and the four radar probes are arranged at four equally divided points of a section circle at the same height of the tower.

[0013] Optionally, in some embodiments of the present invention, the distance between the multiple radar probes and the top of the tower is greater than a third distance and less than a fourth distance, wherein the third distance is one-third of the length of the blade, and the fourth distance is one-third of the distance between the tip of the blade and the bottom of the tower plus one-third of the length of the blade.

[0014] Optionally, in some embodiments of the present invention, the multiple radar probes are mounted on the tower by welding, bonding, screwing, riveting or snapping.

[0015] A second aspect of the present invention provides a blade clearance distance monitoring method, which is applied to the blade clearance distance monitoring system described in the first aspect of the present invention and any optional implementation of the first aspect. The method may include:

[0016] When the blade sweeps across the tower, detection is performed by the multiple radar probes to obtain detection data;

[0017] According to the detection data, the current clearance distance between the blade and the tower is obtained by the controller.

[0018] Optionally, in some embodiments of the present invention,

[0019] The detecting by the multiple radar probes to obtain detection data includes:

[0020] Recording the distance information and time measured by the multiple radar probes;

[0021] Obtaining, by the controller, a current clearance distance between the blade and the tower according to the detection data, including:

[0022] The controller determines a current clearance distance between the blade and the tower according to the time when the distance information is measured and the distance information.

[0023] Optionally, in some embodiments of the present invention, the plurality of radar probes include a first radar probe and a second radar probe;

[0024] The detecting by the multiple radar probes to obtain detection data includes:

[0025] Obtaining a first curve of clearance distance and time through detection by the first radar probe;

[0026] A second curve of clearance distance and time is obtained by detecting the second radar probe;

[0027] Obtaining, by the controller, a current clearance distance between the blade and the tower according to the detection data, including:

[0028] Determining, by the controller, that the minimum clearance distance corresponding to the first curve is a first current minimum clearance distance;

[0029] Determining, by the controller, that the minimum clearance distance corresponding to the second curve is a second current minimum clearance distance;

[0030] When the first current minimum clearance distance is greater than the second current minimum clearance distance, the controller determines that the current minimum clearance distance between the blade and the tower is the second current minimum clearance distance.

[0031] Optionally, in some embodiments of the present invention,

[0032] The multiple radar probes include a third radar probe, a fourth radar probe, and a fifth radar probe. When the blade sweeps across the tower, the multiple radar probes are used to perform detection to obtain detection data, including:

[0033] When the blade sweeps across the tower, detection is performed by the third radar probe to obtain a third curve of clearance distance and time;

[0034] The step of obtaining, by the controller, a current clearance distance between the blade and the tower according to the detection data includes:

[0035] Determining, by the controller, that the minimum clearance distance corresponding to the third curve is a third current minimum clearance distance;

[0036] The method further comprises:

[0037] When the time point corresponding to the third current minimum clearance distance falls within a first time range, the fourth radar probe is turned on by the controller, wherein the fourth radar probe is on a first side of the third radar probe, the first time range is a range between a starting time point and a center time point corresponding to the third curve, and the center time point is a center point between a starting time point and an ending time point corresponding to the third curve;

[0038] When the time point corresponding to the third current minimum clearance distance belongs to the second time range, the fifth radar probe is turned on by the controller, wherein the fifth radar probe is on the second side of the third radar probe, and the second time range is the range where the end time point and the center time point corresponding to the third curve are located, and the center time point is the center point between the start time point and the end time point corresponding to the third curve.

[0039] Optionally, in some embodiments of the present invention, the method further includes:

[0040] If the current clearance distance is less than the preset minimum clearance distance, the controller determines that the blade is in a safe state.

[0041] It can be seen from the above technical solutions that the embodiments of the present invention have the following advantages:

[0042] In an embodiment of the present invention, the clearance distance monitoring system includes multiple radar probes, a tower, and a wind turbine, wherein the wind turbine includes blades. The multiple radar probes are mounted on the tower, and the wind turbine is mounted on the top of the tower. The distance between the multiple radar probes and the top of the tower is greater than a first distance and less than a second distance, wherein the first distance is one-half the length of the blade, and the second distance is one-half the distance between the blade tip and the bottom of the tower plus one-half the length of the blade. The clearance distance is measured using radar probes. Because radar probes have strong penetrating power and can operate normally in adverse weather such as rain, fog, dust, and strong winds, the measured clearance distance is highly reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments and the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention, and other drawings can be obtained based on these drawings.

[0044] Figure 1 A schematic diagram of an embodiment of a blade clearance distance monitoring system according to an embodiment of the present invention;

[0045] Figure 2 A schematic diagram of the layout of multiple radar probes in an embodiment of the present invention;

[0046] Figure 3 Schematic diagram of the coverage area formed by radar waves;

[0047] Figure 4 A schematic diagram of an embodiment of a blade clearance distance monitoring method according to an embodiment of the present invention;

[0048] Figure 5 A schematic diagram of radar probe clearance distance monitoring in an embodiment of the present invention;

[0049] Figure 6 Schematic diagram of a first curve and a second curve regarding clearance distance and time in an embodiment of the present invention;

[0050] Figure 7 Schematic diagram of the clearance distance measured after one rotation of a three-blade impeller in an embodiment of the present invention. DETAILED DESCRIPTION

[0051] The embodiments of the present invention provide a blade clearance distance monitoring system and a blade clearance distance monitoring method, which are used to obtain a highly reliable clearance distance by measuring with a radar probe.

[0052] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. All the embodiments in the present invention should fall within the scope of protection of the present invention.

[0053] The technical solution of the present invention is further described below by way of examples. Figure 1 FIG. 1 is a schematic diagram of an embodiment of a blade clearance distance monitoring system according to an embodiment of the present invention.

[0054] The blade clearance distance monitoring system includes a plurality of radar probes 101, a controller 102, a tower 103 and a wind turbine 104, wherein the wind turbine 104 includes blades 1041;

[0055] Among them, multiple radar probes 101 and a controller 102 are installed on a tower 103, the controller 102 is connected to the multiple radar probes 101, and a wind turbine 104 is installed on the top of the tower 103;

[0056] The distance between multiple radar probes 101 and the top of the tower 103 is greater than the first distance and less than the second distance, wherein the first distance is half the length of the blade 1041, and the second distance is half the distance between the tip of the blade 1041 and the bottom of the tower 103 plus half the length of the blade 1041.

[0057] It is understandable that the blade clearance distance monitoring system may also be referred to as a wind turbine blade clearance distance monitoring system.

[0058] In the embodiment of the present invention, a radar probe is mainly used to monitor the clearance distance between the blades and the tower of the wind turbine. Since the radar probe has a strong penetrating power and can work normally in adverse weather conditions such as rain, fog, dust, and strong winds, the reliability of the measured clearance distance is relatively high.

[0059] Optionally, in some embodiments of the present invention, the radar probe 101 includes a millimeter wave radar or other microwave radar. The radar probe can be a separate ranging radar probe or a radar probe that can simultaneously detect distance and position (such as angle), without specific limitation.

[0060] Millimeter-wave radar, with its strong penetrating power, is unaffected by extreme weather conditions such as rain, fog, dust, haze, and low temperatures. Its ranging accuracy can reach the centimeter level, and its fast response speed fully meets the requirements for wind turbines in various environments, such as oceans, foggy mountainous areas, grasslands, and neighboring regions. It is more suitable for this application environment than lidar, ultrasonic radar, and infrared radar.

[0061] Optionally, in some embodiments of the present invention, the plurality of radar probes 101 include three radar probes, and the three radar probes are arranged at three equal points of a section circle at the same height of the tower 103; or,

[0062] The plurality of radar probes 101 include four radar probes, and the four radar probes are arranged at four equal points of a section circle at the same height of the tower 103; or,

[0063] The plurality of radar probes 101 include five radar probes, and the five radar probes are arranged at five equally divided points of a section circle at the same height of the tower 103; or

[0064] The plurality of radar probes 101 include six radar probes, and the six radar probes are arranged at six equal points of a section circle at the same height of the tower 103 .

[0065] It is understandable that the number of radar probes is not limited and can be adjusted according to actual conditions. Figure 2As shown in FIG, a schematic diagram of the layout of multiple radar probes in an embodiment of the present invention. Multiple probes are installed at equal intervals on the circumference of the tower 103 to form an S1-S2 annular effective ranging area with no blind spots. Figure 3 The figure below is a schematic diagram of the coverage area formed by radar waves. Figure 3 As shown, the specific requirements are: minimum clearance distance < maximum measurement distance of the radar probe; and the blind area of ​​the clearance monitoring radar is within the minimum clearance distance.

[0066] Here is Figure 1-Figure 3 A brief description of the parameters that appear in is as follows:

[0067] The number of radar probes is determined by the tower radius R, the minimum clearance distance S1 of the blades, and the detection angle a of the radar wave of the radar probe.

[0068]

[0069] Among them, R1: radar blind zone radius, is a known parameter;

[0070] S: Clearance distance, the distance between the blade and the center axis of the tower when the blade sweeps across the front of the tower;

[0071] S2: The maximum measurement distance of the radar probe, generally greater than the maximum blade clearance distance;

[0072] S1: minimum clearance distance;

[0073] R1: Radar blind zone radius;

[0074] H: The installation height of the radar probe, generally at the minimum distance between the blade tip and the bottom of the tower, and the height can be adjusted appropriately as needed;

[0075] a: Horizontal detection angle of the radar probe (radar probe property; the detection angle can be changed by changing the hardware design according to performance requirements);

[0076] As shown in Formula 1, the number n of radar probes and the detection angle a of the radar probes can be determined.

[0077] Optionally, in some embodiments of the present invention, the distance between multiple radar probes 101 and the top of the tower 103 is greater than a third distance and less than a fourth distance, wherein the third distance is one-third of the length of the blade 1041, and the fourth distance is one-third of the distance between the tip of the blade 1041 and the bottom of the tower 103 plus one-third of the length of the blade 1041.

[0078] Optionally, in some embodiments of the present invention, the distance between multiple radar probes 101 and the top of the tower 103 is greater than the fifth distance and less than the sixth distance, wherein the fifth distance is one-quarter of the length of the blade 1041, and the fifth distance is one-quarter of the distance between the tip of the blade 1041 and the bottom of the tower 103 plus one-quarter of the length of the blade 1041.

[0079] Optionally, in some embodiments of the present invention, the distance between multiple radar probes 101 and the top of the tower 103 is greater than the seventh distance and less than the eighth distance, wherein the seventh distance is one-fifth of the length of the blade 1041, and the eighth distance is one-quarter of the distance between the tip of the blade 1041 and the bottom of the tower 103 plus one-fifth of the length of the blade 1041.

[0080] Optionally, in some embodiments of the present invention, the distance between the multiple radar probes 101 and the bottom of the tower 103 is consistent with the distance between the tip of the blade 1041 and the ground.

[0081] Optionally, in some embodiments of the present invention, multiple radar probes 101 are mounted on the tower 103 by welding, bonding, screwing, riveting or snapping.

[0082] Optionally, in some embodiments of the present invention, the controller 102 is connected to the multiple radar probes 101 via wired or wireless means.

[0083] Optionally, in some embodiments of the present invention, the controller 102 is mounted on the tower 103 by welding, bonding, screwing, riveting or snapping.

[0084] Optionally, in some embodiments of the present invention, the distance between the multiple radar probes 101 and the top of the tower 103 is equal to the length of the blade 1041 .

[0085] like Figure 4 FIG. 1 is a schematic diagram of an embodiment of a blade clearance distance monitoring method according to an embodiment of the present invention, wherein the method is applied to Figure 1 The blade clearance distance monitoring system shown may include:

[0086] 401. When the blade sweeps across the tower, detection is performed using the multiple radar probes to obtain detection data.

[0087] The detection by the multiple radar probes to obtain the detection data may include: recording the distance information of the multiple radar probes; and recording the time when the multiple radar probes measure the distance information.

[0088] For example, Figure 5FIG. 1 is a schematic diagram of a radar probe for monitoring clearance distance in an embodiment of the present invention. When the blades pass through the front of the tower, the radar probe can detect a series of data.

[0089] 402. According to the detection data, obtain, via the controller, a current clearance distance between the blade and the tower.

[0090] Obtaining the current clearance distance between the blade and the tower through the controller according to the detection data may include: determining the current clearance distance between the blade and the tower through the controller according to the time when the distance information is measured and the distance information.

[0091] Optionally, in some embodiments of the present invention, the multiple radar probes include a first radar probe and a second radar probe; and performing detection by the multiple radar probes to obtain detection data may include: obtaining a first curve of clearance distance and time by detecting by the first radar probe; and obtaining a second curve of clearance distance and time by detecting by the second radar probe;

[0092] According to the detection data, obtaining the current clearance distance between the blade and the tower through the controller may include: determining through the controller that the minimum clearance distance corresponding to the first curve is a first current minimum clearance distance; determining through the controller that the minimum clearance distance corresponding to the second curve is a second current minimum clearance distance; when the first current minimum clearance distance is greater than the second current minimum clearance distance, determining through the controller that the current minimum clearance distance between the blade and the tower is the second current minimum clearance distance.

[0093] Optionally, in some embodiments of the present invention, the multiple radar probes include a third radar probe, a fourth radar probe, and a fifth radar probe, and when the blade sweeps across the tower, detecting by the multiple radar probes to obtain detection data may include: when the blade sweeps across the tower, detecting by the third radar probe to obtain a third curve of clearance distance and time;

[0094] Obtaining, by the controller, the current clearance distance between the blade and the tower according to the detection data may include: determining, by the controller, a minimum clearance distance corresponding to the third curve as a third current minimum clearance distance;

[0095] The method further comprises:

[0096] When the time point corresponding to the third current minimum clearance distance falls within a first time range, the fourth radar probe is turned on by the controller, wherein the fourth radar probe is on a first side of the third radar probe, the first time range is a range between a starting time point and a center time point corresponding to the third curve, and the center time point is a center point between a starting time point and an ending time point corresponding to the third curve;

[0097] When the time point corresponding to the third current minimum clearance distance belongs to the second time range, the fifth radar probe is turned on by the controller, wherein the fifth radar probe is on the second side of the third radar probe, and the second time range is the range where the end time point and the center time point corresponding to the third curve are located, and the center time point is the center point between the start time point and the end time point corresponding to the third curve.

[0098] For example, when the impeller rotates one circle, the clearance distance of the blade tip detected by radar probes A and B is as follows: Figure 6 The figure shows a schematic diagram of the first and second curves of clearance distance versus time in an embodiment of the present invention. The curves (data) of the clearance distance from blade 1 to the tower are collected by radar probes A and B, respectively. Radar probe A measures the first current minimum clearance distance as S11, and radar probe B measures the second current minimum clearance distance as S12. The chord height of arc AB is h, and the smaller value of (S11, S12) is taken as the current minimum clearance distance S13. At this time, the current minimum clearance distance of blade 1 is: S13(-h, 0). S13(-h, 0) means that if the measured current minimum clearance distance is 5 meters, there is a deviation between the converted value and the actual value, and the deviation is between 0 and h.

[0099] like Figure 7 As shown in FIG, it is a schematic diagram of the clearance distance measured when the three-blade impeller rotates one circle in an embodiment of the present invention. Figure 7 The clearance value-time data (ST plot) measured by radar probe A can be used to determine whether the minimum clearance value is to the left or right of radar A's horizontal centerline based on the relationship between the measured minimum clearance time t and t1 and t2. The corresponding radar is then activated, while the remaining radars are deactivated. This means that two radar probes are simultaneously operating. This increases the radar probe's service life and reduces maintenance costs. Radar A's horizontal centerline is the midpoint between the curve's start and end time points.

[0100] 403. If the current clearance distance is less than the preset minimum clearance distance, determine, through the controller, that the blade is in a safe state.

[0101] Optionally, if the current clearance distance is greater than or equal to the preset minimum clearance distance, the controller determines that the blade is in a dangerous state and may prompt the user to reset the blades of the wind turbine.

[0102] In an embodiment of the present invention, when a blade passes over the tower, the multiple radar probes detect the blade and obtain detection data. Based on the detection data, the controller determines the current clearance distance between the blade and the tower. If the current clearance distance is less than the preset minimum clearance distance, the clearance distance monitoring system determines that the blade is in a safe state through the controller. In other words, the multiple radar probes detect the current clearance distance between the blade and the tower, and further, based on the current clearance distance, whether the blade is in a safe state can be determined.

[0103] This clearance distance monitoring system can use millimeter-wave radar as the main ranging solution, using millimeter-wave radar probes evenly distributed around the tower and a dedicated controller to monitor the real-time clearance distance between the blades and the tower, and can provide a variety of data provision methods as needed.

[0104] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0105] In the several embodiments provided by the present invention, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the units is merely a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interface, device or unit, which can be electrical, mechanical or other forms.

[0106] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0107] In addition, the functional units in the various embodiments of the present invention may be integrated into a single processing unit, each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0108] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0109] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments can still be modified, or some of the technical features thereof can be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A blade clearance distance monitoring method, characterized in that: The method comprises: When the blade sweeps across the tower, detection is performed by multiple radar probes to obtain detection data, wherein the multiple radar probes include a first radar probe, a second radar probe, a third radar probe, a fourth radar probe, and a fifth radar probe, and the radar probe includes a millimeter wave radar; According to the detection data, a current clearance distance between the blade and the tower is obtained by a controller; The detecting by the multiple radar probes to obtain detection data includes: Obtaining a first curve of clearance distance and time through detection by the first radar probe; A second curve of clearance distance and time is obtained by detecting the second radar probe; A third curve of clearance distance and time is obtained by detecting the third radar probe; The method of obtaining, by a controller, a current clearance distance between the blade and the tower according to the detection data includes: Determining, by the controller, that the minimum clearance distance corresponding to the first curve is a first current minimum clearance distance; Determining, by the controller, that the minimum clearance distance corresponding to the second curve is a second current minimum clearance distance; Determining, by the controller, that the minimum clearance distance corresponding to the third curve is a third current minimum clearance distance; When the first current minimum clearance distance is greater than the second current minimum clearance distance, determining, by the controller, the current minimum clearance distance between the blade and the tower as the second current minimum clearance distance; The method further comprises: When the time point corresponding to the third current minimum clearance distance belongs to a first time range, the fourth radar probe is turned on by the controller, wherein the fourth radar probe is on a first side of the third radar probe, the first time range is a range between a starting time point and a center time point corresponding to the third curve, and the center time point is a center point between a starting time point and an ending time point corresponding to the third curve; When the time point corresponding to the third current minimum clearance distance belongs to a second time range, the fifth radar probe is turned on by the controller, wherein the fifth radar probe is on the second side of the third radar probe, the second time range is the range between the end time point and the center time point corresponding to the third curve, and the center time point is the center point between the start time point and the end time point corresponding to the third curve; The method further comprises: If the current clearance distance is less than a preset minimum clearance distance, the controller determines that the blade is in a safe state.

2. A blade clearance distance monitoring system, characterized in that: The blade clearance distance monitoring system is applicable to the method according to claim 1, wherein the system comprises a plurality of radar probes, a controller, a tower and a wind turbine, wherein the radar probe comprises a millimeter wave radar, and the wind turbine comprises blades; The multiple radar probes and the controller are arranged on the tower, the controller is connected to the multiple radar probes, and the wind turbine is arranged on the top of the tower; The distances between the multiple radar probes and the top of the tower are greater than a first distance and less than a second distance, wherein the first distance is half the length of the blade, and the second distance is half the distance between the blade tip and the bottom of the tower plus half the length of the blade; The multiple radar probes include five radar probes, and the five radar probes are arranged at five equally divided points of a section circle at the same height of the tower.

3. The blade clearance distance monitoring system according to claim 2, characterized in that: The multiple radar probes are mounted on the tower by welding, bonding, screwing, riveting or snapping.

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