Wind power tower drum defect detection surface wave sensor and detection method thereof

Abstract

The invention provides a wind power tower drum defect detection surface wave sensor and a detection method thereof. The sensor comprises a shell, a magnetic attraction part and a transmitting and receiving integrated signal part. The magnetic attraction component adopts a U-shaped structure and is formed by connecting two ends of a strip-shaped magnet with a magnetizer respectively; and the receiving and transmitting integrated signal component is positioned at the opening end of the U-shaped structure of the magnetic component. The sensor is adsorbed on the surface of the outer wall of a tower drum, meanwhile, a near surface layer of the outer wall of the tower drum presents a strong bias magnetic field, radio frequency pulse current is introduced into a transmitting and receiving integrated signal component, a high-frequency dynamic magnetic field is induced on the near surface, surface waves in any direction are excited and received under the action of the two fields, and echo signals of the surface waves are analyzed. And judging whether the outer wall of the tower drum has defects. The sensor disclosed by the invention is small in size and capable of meeting mobile scanning, the propagation distance of the excited surface wave is long, the recognition precision is high, the working difficulty of tower drum defect detection is reduced, circumferential and axial defect detection is realized, and the detection efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the field of surface wave nondestructive testing, and in particular to a surface wave sensor for detecting defects in a wind power tower and a detection method thereof. Background Art

[0002] As an efficient and clean form of energy, wind power has gradually become an important part of the energy structure adjustment and emission reduction goals of various countries. According to the International Renewable Energy Agency (IRENA), wind power installed capacity has achieved rapid growth in the past decade and is expected to continue to rise in the future. In the field of wind power generation, wind turbine towers are one of the key structural components of wind turbines, and their performance is directly related to the safety, economy and sustainability of wind farms. Whether it is onshore wind power or offshore wind power, wind turbine towers need to withstand the test of various extreme environments and complex physical conditions.

[0003] Wind turbine towers are usually made of steel and must withstand adverse factors such as wind erosion, humidity changes, and large temperature fluctuations. Especially in offshore environments, high-salinity seawater, strong winds, and tidal effects are more likely to cause material corrosion. These factors will accelerate the aging of the tower material, resulting in reduced structural strength, shortened fatigue life, and even serious safety hazards, leading to economic losses and personal injuries. Therefore, timely and accurate detection and evaluation of the defect status of wind turbine towers is crucial to ensure the safe operation of wind power facilities and extend their service life.

[0004] At present, the commonly used wind turbine tower inspection methods mainly include visual inspection and ultrasonic inspection. Although visual inspection is intuitive, it requires additional safety measures and usually requires the use of aerial work equipment or drones. It is time-consuming and depends on the professional level of the inspectors, and the inspection accuracy is low. Ultrasonic inspection, as a non-destructive inspection technology, has been widely used in the wind power industry due to its high efficiency, accuracy and strong adaptability. However, for defects in wind turbine towers, especially defects concentrated in the near-surface area, traditional ultrasonic guided waves and body wave sensors mainly target internal defects in materials, making it difficult to achieve high-precision near-surface inspection.

[0005] In this case, surface wave sensors are very sensitive to detecting surface defects of wind turbine towers due to their ability to propagate along the surface of materials. The detection results can usually be accurate to the millimeter level, making them very suitable for corrosion defect detection of wind turbine towers. However, current surface wave sensors still face some challenges in practical applications, such as complex structure, low integration, and susceptibility to environmental interference, which limits their widespread application in wind turbine tower detection.

[0006] Therefore, there is an urgent need for an innovative wind turbine tower defect detection technology that can effectively overcome the defects of existing technologies, so as to improve the accuracy, efficiency and reliability of detection and ensure the sustainable development of the wind power industry. Summary of the invention

[0007] The purpose of the present invention is to address the deficiencies in the prior art and provide a surface wave sensor for detecting defects in a wind turbine tower and a detection method thereof, which can realize rapid detection, precise positioning and global scanning of surface defects in a wind turbine tower.

[0008] In order to achieve the above purpose, the present invention adopts the following technical scheme: In a first aspect, the present invention provides a surface wave sensor for detecting defects in a wind turbine tower, the sensor comprising a shell, and a magnetic attraction component and a transceiver signal component located inside the shell; the transceiver signal component is located at the bottom of the surface wave sensor; the magnetic attraction component is located at the top of the transceiver signal component; The magnetic attraction component adopts a U-shaped structure, including a bar magnet and two magnetic conductors; the two ends of the bar magnet are respectively connected to a magnetic conductor; The U-shaped structure opening end of the magnetic attraction component faces the bottom of the surface wave sensor, and the transceiver integrated signal component is located at the U-shaped structure opening end of the magnetic attraction component; The transceiver integrated signal component is located directly below the bar magnet and is used to excite high-frequency short pulse current and simultaneously receive the echo signal and transmit it to the terminal.

[0009] Preferably, a filling layer is provided between the transceiver-in-one signal component and the bar magnet; more preferably, the filling layer is made of insulating material.

[0010] Preferably, the magnetic attraction force F of the bar magnet satisfies , Indicates the minimum threshold of magnetic attraction force at which the sensor can be adsorbed on the outer wall of the wind turbine tower. Indicates the maximum threshold of the magnetic attraction force with which the sensor can be adsorbed on the outer wall of the wind turbine tower.

[0011] Preferably, the transceiver signal component adopts a folded transceiver signal coil, including a plurality of straight line segments arranged in parallel at equal intervals, and adjacent straight line segments are connected by connecting segments; the straight line segments are used to excite surface waves, and the high-frequency dynamic magnetic fields of adjacent straight line segments are in opposite directions. More preferably, in the transceiver signal component, the spacing between adjacent straight line segments is half the wavelength of the surface wave, so that the surface waves excited by each straight line segment are superimposed in the same phase, thereby improving the strength of the surface wave signal. The width of the transceiver signal component is smaller than the width of the bar magnet.

[0012] Preferably, the sensor further comprises a moving wheel arranged at the bottom.

[0013] Preferably, the lift-off value L of the transceiver-integrated signal component should be less than 1 mm, that is, the distance between the transceiver-integrated signal component and the outer surface of the tower should be less than 1 mm.

[0014] In a second aspect, the present invention provides a method for detecting defects in a wind turbine tower, the method comprising: S1. Adsorbing the sensor on the outer wall of the wind turbine tower by magnetic attraction; S2. A high-frequency short pulse current is passed into the integrated signal transceiver component, thereby exciting a high-frequency dynamic magnetic field near the surface of the wind turbine tower; at the same time, the bar magnet induces a static bias magnetic field in the near-surface area; the high-frequency dynamic magnetic field interacts with the static bias magnetic field, and surface waves are excited based on the magnetostrictive mechanism, which propagate around the sensor; S3. When the surface wave propagates and encounters a defective area, a reflected echo is formed. The echo interacts with the static bias magnetic field, and the echo signal is received by the transceiver integrated signal component based on the inverse magnetostrictive effect. The defects include corrosion, end wall, weld, coating wear, and coating peeling. S4. Control the movement of the sensor according to the preset sensor scanning path and scanning interval, repeat steps S2 and S3 until the whole circumference of the tower is scanned, and finally analyze and process the echo signal returned by the integrated signal transceiver component to obtain the defect area analysis result.

[0015] Preferably, the wavelength of the surface wave Satisfy the following: Among them, v R is the surface wave phase velocity, v s is the shear wave velocity of the surface wave, v p is the shear wave velocity of the surface wave, and f is the surface wave excitation frequency.

[0016] Compared with the prior art, the present invention has at least the following beneficial effects: The sensor of the present invention is a movable trolley structure as a whole, with a highly integrated surface wave transceiver structure inside. The shell is made of lightweight aluminum alloy material, and a filling layer is set between the transceiver signal component and the bar magnet to enhance the structural stability and strength and reduce the weight. This ingenious design makes it compact, small, easy to operate and move, in sharp contrast to the bulky sensors in the prior art, greatly improving the flexibility and convenience of the detection process.

[0017] The magnetic attraction component of the present invention adopts a U-shaped structure, and the two ends of the strip magnet are bonded to the magnetic conductor, which can not only effectively guide the direction of the magnetic lines of force and enhance the local magnetic field, but also can be adsorbed to the outer wall of the wind power tower through magnetic force, and the magnetic attraction force is within the appropriate threshold range, ensuring stable adsorption while facilitating position adjustment. In addition, the moving wheel at the bottom of the sensor further assists it to move flexibly on the surface of the tower, achieve precise positioning, and can adapt to the needs of different detection positions and paths, effectively solving the problem of fixed sensor position and difficulty in flexible detection in the prior art.

[0018] The present invention generates a high-frequency dynamic magnetic field by passing a high-frequency short pulse current into the folded transceiver integrated signal coil, which interacts with the static bias magnetic field induced by the bar magnet to excite surface waves. The surface waves can propagate in all directions, thereby simultaneously detecting circumferential and axial defects. This feature overcomes the defects of the prior art of single detection direction and large limitations, and realizes comprehensive detection of wind turbine tower defects.

[0019] The propagation characteristics of the surface waves excited by the present invention make it extremely sensitive to surface defects of wind turbine towers, with a detection accuracy of up to millimeter level, and can accurately locate the defect position. In the data analysis and processing stage, the accuracy of the detection results is further improved through the precise analysis of the echo signal, effectively avoiding the problem of defect omission or misjudgment caused by insufficient detection accuracy in the prior art.

[0020] The sensor of the present invention can be easily moved on the outer wall surface of the wind turbine tower, and can be detected according to the preset scanning path and spacing. It can quickly cover a large area, efficiently complete the whole week scanning task, significantly shorten the detection time, and improve the detection efficiency. Compared with traditional detection methods (such as visual detection requires the use of high-altitude working equipment or drones and is time-consuming and relies on manual experience, and ultrasonic detection has limited accuracy and low detection efficiency for near-surface defects), the present invention greatly improves the detection speed while ensuring the detection accuracy.

[0021] Finally, during the entire detection process, the sensor only requires external equipment to provide high-frequency short-pulse current to excite surface waves, and there is no need for a continuous high-energy consumption operation mode. While ensuring the normal realization of the detection function, it effectively reduces power consumption, reduces energy consumption and equipment operating costs, and improves the economy and practicality of the equipment.

[0022] To sum up, the wind turbine tower defect detection surface wave sensor and its detection method of the present invention show significant advantages in structural design, detection function and working performance, effectively solving many problems in the existing wind turbine tower detection technology, and providing an efficient, accurate, reliable and economical solution for wind turbine tower defect detection, which is of great significance to ensuring the safe operation of wind power facilities and promoting the sustainable development of the wind power industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A flow chart of a method for detecting corrosion defects in a wind turbine tower provided by the present invention.

[0024] Figure 2 This is a schematic diagram of the working mode of the surface wave sensor for corrosion defect detection of the present invention.

[0025] Figure 3 This is a working principle diagram of the corrosion defect detection surface wave sensor of the present invention.

[0026] Figure 4 It is a top view of the folded transmitting and receiving integrated coil structure of the present invention.

[0027] Markings in the figure: shell 1, magnetic attraction component 2, bar magnet 21, magnetic conductor 22, transceiver integrated signal component 3, straight line segment 31, filling layer 4, moving wheel 5, static bias magnetic field 6, high-frequency dynamic magnetic field 7, surface wave 8. DETAILED DESCRIPTION

[0028] The present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0029] like Figure 2-3 As shown, the present invention aims to provide an efficient, accurate and practical surface wave sensor for wind turbine tower defect detection. The sensor is in the form of a movable trolley structure, and the interior is a highly integrated surface wave transceiver structure. The sensor includes a housing 1, a magnetic component 2 located inside the housing 1, a transceiver signal component 3 and a moving wheel 5 arranged at the bottom. The transceiver signal component 3 is located at the bottom of the surface wave sensor; the magnetic component 2 is located at the top of the transceiver signal component 3;

[0030] The shell 1 is made of lightweight aluminum alloy, which ensures that the overall structure is light and has a certain strength.

[0031] The magnetic attraction component 2 adopts a U-shaped structure, including a strip magnet 21 and two magnetic conductors 22; the two ends of the strip magnet 21 are respectively connected to a magnetic conductor 22; the strip magnet 21 and the magnetic conductor 22 can be connected by bonding, and the bonding material can be a high magnetic permeability material for guiding the direction of the magnetic lines of force of the strip magnet and enhancing the local magnetic field. The bonding material uses an insulating sealant to prevent moisture penetration.

[0032] The U-shaped opening end of the magnetic attraction component 2 faces the bottom of the surface wave sensor, and the transceiver integrated signal component 3 is located at the U-shaped opening end of the magnetic attraction component 2; The transceiver integrated signal component 3 is located directly below the bar magnet 21; A filling layer 4 is provided between the transceiver integrated signal component 3 and the bar magnet 21 ; specifically, the filling layer 4 is made of insulating material, such as foam, to enhance the structural stability and strength of the sensor while reducing weight.

[0033] The sensor is placed on the outer wall of the wind turbine tower. With the help of the magnetic force of the magnetic attraction component 2, the sensor can be tightly attached and fixed on the outer wall of the tower. It is necessary to ensure that the magnetic attraction force F of the bar magnet 21 satisfies , Indicates the minimum threshold of magnetic attraction force at which the sensor can be adsorbed on the outer wall of the wind turbine tower. Indicates the maximum threshold of magnetic attraction that the sensor can adhere to the outer wall of the wind turbine tower. In actual operation, you can also choose a detachable method such as a suction cup, bonding or grasping to assist in fixing the sensor according to the specific situation to ensure that the sensor remains stable during the detection process. After the fixation is completed, determine the path and spacing of the local scan according to the detection requirements to prepare for subsequent detection work.

[0034] The sensor is connected to an external device via a connecting line of the integrated signal transceiver component 3, and the external device integrates key components such as a signal generator and an acquisition card.

[0035] Start the signal generator to pass a high-frequency short pulse current into the transceiver signal component 3. At this time, the folded transceiver signal coil used in the transceiver signal component 3 begins to function, with the coil winding direction perpendicular to the magnetic field direction of the magnetic conductor 22 and the coil width being smaller than the width of the bar magnet 21. Figure 2 The folded transceiver signal coil includes a plurality of straight line segments 31 arranged in parallel and at equal intervals, and adjacent straight line segments 31 are connected by connecting segments; the straight line segments 31 are used to excite the surface wave 8, and the currents of adjacent straight line segments 31 are opposite, so the directions of the high-frequency dynamic magnetic field 7 are also opposite. The spacing between adjacent straight line segments 31 is half the wavelength of the surface wave 8, so that the surface waves excited by each straight line segment 31 are superimposed in the same phase, thereby improving the strength of the surface wave signal. This embodiment can use a transceiver signal coil arranged in a "J" shape, see Figure 4 The whole structure is a flexible film structure, which is made by flexible printed circuit technology. The center distance d of adjacent coil clusters is half the wavelength of the surface wave excited. The width of a single-turn coil cluster does not exceed half the wavelength, and the current directions of adjacent turn coils are opposite. Under the action of high-frequency short pulse current, a high-frequency dynamic magnetic field is excited on the near surface of the tower 7.

[0036] At the same time, the bar magnet 21 induces a static bias magnetic field 6 near the surface of the tower. The high-frequency dynamic magnetic field 7 interacts with the static bias magnetic field 6, and based on the magnetostrictive mechanism, successfully excites a surface wave 8, which propagates around the sensor. The wavelength of the surface wave satisfies the following formula, and is preferably less than one-quarter of the tower wall thickness:

[0037] Among them, v R is the surface wave phase velocity, v s is the shear wave velocity, v p is the shear wave velocity, and f is the surface wave excitation frequency.

[0038] The lift-off value L of the transceiver-integrated signal component 3 should be less than 1 mm, that is, the distance between the transceiver-integrated signal component 3 and the outer surface of the tower should be less than 1 mm.

[0039] In order to more comprehensively and deeply understand the practical application effects and advantages of the wind turbine tower defect detection surface wave sensor and the detection method thereof involved in the present invention, they will be further elaborated in conjunction with specific embodiments below.

[0040] This embodiment provides a method for detecting defects at the bottom of a wind turbine tower using the above-mentioned new sensor with small size, simple structure, strong adaptability and high efficiency, which can realize rapid detection, precise positioning and regional scanning of corrosion defects of wind turbine towers, such as Figure 1 The steps include: A typical onshore wind turbine tower can be selected as the inspection object, focusing on its bottom area, which is close to the ground and easily affected by humidity changes, rain erosion and possible wind erosion, and is a defect-prone area. Of course, an offshore wind turbine tower can also be selected as the inspection object, focusing on its weld area, which is prone to weld defects, corrosion, and coating peeling due to the dual influence of welding technology and the harsh offshore environment.

[0041] Step 1: Fix the surface wave sensor of the present invention on the outer wall of the tower. Since the sensor has a built-in magnetic attraction component 2, the sensor can be closely attached to and fixed on the outer wall of the tower by magnetic force. In this process, the magnetic attraction force F of the bar magnet 21 is measured. and At the same time, in order to further ensure the accuracy and stability of the sensor position, auxiliary tools can be used to fine-tune it to align it with the predetermined scanning path and determine the appropriate scanning spacing, such as setting it to collect data every 5 cm. In addition, detachable methods such as suction cups, bonding or grasping can also be used to determine the path and spacing of local scanning.

[0042] Step 2: Connect the transceiver signal component 3 to an external device through a connecting line. The external device integrates a signal generator and an acquisition card. The signal generator passes a high-frequency short pulse current of, for example, 5-8MHz into the transceiver signal component 3, thereby exciting a high-frequency dynamic magnetic field 7 near the surface of the tower, which interacts with the static bias magnetic field 6 induced by the bar magnet in the near-surface area of ​​the tower, and excites a surface wave 8 based on the magnetostrictive mechanism, which propagates around the sensor. Since the lift-off value L between the bottom of the sensor and the outer wall of the tower is less than 1mm, it is ensured that the surface wave can effectively interact with the tower surface.

[0043] Step 3: When the surface wave propagates and encounters tower defects, it will form a reflected echo. These defects include but are not limited to corrosion pits (circumferential corrosion or axial corrosion), end wall, weld (weld area. When propagating, once it encounters defects such as pores in the weld, slag inclusions, or weld thinning caused by corrosion, it will produce reflected echoes, coating wear, coating peeling, etc. The reflected echo interacts with the bias magnetic field generated by the bar magnet. Based on the inverse effect of magnetostriction, the echo signal is received through the integrated signal transceiver component 3, and the acquisition card of the external device receives the echo signal. The acquisition card performs a series of processing operations on the echo signal, including filtering, amplification, and storage. The filtering operation can effectively remove noise interference in the signal and improve the signal-to-noise ratio of the signal; the amplification operation enhances the strength of the signal, which is convenient for subsequent analysis; the storage operation ensures the integrity of the signal data and provides data support for subsequent in-depth analysis. For example, in this detection, the acquisition card uses a Butterworth filter for filtering, and sets the amplification factor to 100 times to ensure that the quality and strength of the echo signal are sufficient for subsequent analysis.

[0044] Step 4: According to the scanning path and scanning spacing, change the sensor position along the scanning direction, repeat steps 2 and 3, complete the detection of circumferential corrosion defects and axial corrosion defects, and then analyze and process the stored signals to determine the defect location, size and other parameters. For example, through professional signal processing software, extract and analyze the time domain and frequency domain characteristics of the signal. Observe the arrival time of the echo signal, calculate the distance between the defect and the sensor based on the known surface wave propagation speed (predetermined according to material properties and detection environment); analyze the amplitude change of the echo signal, and combine it with the pre-established defect feature database to preliminarily determine the type and severity of the defect.

[0045] After analysis, it was found that the echo signal had obvious abnormal changes at a certain position, such as a peak point before the end echo, which may represent a new reflection source, and it is inferred that it may be a defect. After calculation, the defect position is about 30 cm away from the starting point of the sensor, and according to the signal amplitude and characteristics, it may be a local corrosion defect, and the corrosion depth is expected to be between 2-3 mm. In order to further verify the accuracy of the test results, other detection methods (such as visual inspection after local grinding or micro-damage detection) can be used for comparative verification to ensure the reliability of the test results.

[0046] In summary, the surface wave sensor and detection method of the present invention realizes rapid and accurate detection of wind turbine tower defects through the above series of steps, effectively solves many problems faced by the prior art in wind turbine tower defect detection, and provides strong technical support for the safe and stable operation of the wind power industry.

[0047] The above is a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A surface wave sensor for detecting defects in a wind turbine tower, characterized in that: The sensor comprises a housing (1), and a magnetic attraction component (2) and a transceiver signal component (3) located inside the housing (1); the transceiver signal component (3) is located at the bottom of the surface wave sensor; the magnetic attraction component (2) is located at the top of the transceiver signal component (3); The magnetic attraction component (2) adopts a U-shaped structure, comprising a bar magnet (21) and two magnetic conductors; two ends of the bar magnet (21) are respectively connected to a magnetic conductor; The U-shaped structural opening end of the magnetic attraction component (2) faces the bottom of the surface wave sensor, and the transceiver-in-one signal component (3) is located at the U-shaped structural opening end of the magnetic attraction component (2); The transceiver-integrated signal component (3) is located directly below the bar magnet (21) and is used to receive signals from an external signal generator, to stimulate high-frequency short pulse current, and to receive echo signals and transmit them to the terminal.

2. The sensor according to claim 1, characterized in that A filling layer (4) is provided between the transceiver-in-one signal component (3) and the bar magnet (21).

3. The sensor according to claim 1, characterized in that The magnetic attraction force F of the bar magnet (21) satisfies , Indicates the minimum threshold of magnetic attraction force at which the sensor can be adsorbed on the outer wall of the wind turbine tower. Indicates the maximum threshold of the magnetic attraction force with which the sensor can be adsorbed on the outer wall of the wind turbine tower.

4. The sensor according to claim 1, characterized in that The transceiver signal component (3) adopts a folded transceiver signal coil, comprising a plurality of straight line segments (31) arranged in parallel and at equal intervals, wherein adjacent straight line segments (31) are connected via a connecting segment; the straight line segments (31) are used to excite surface waves (8), and the high-frequency dynamic magnetic fields (7) of adjacent straight line segments (31) are in opposite directions.

5. The sensor according to claim 1, characterized in that In the integrated signal transceiver component (3), the spacing between adjacent straight line segments (31) is half the wavelength of the surface wave (8), so that the surface waves excited by the straight line segments (31) are superimposed in phase, thereby increasing the strength of the surface wave signal.

6. The sensor according to claim 1, characterized in that The width of the integrated signal transceiver component (3) is smaller than the width of the bar magnet (21).

7. The sensor according to claim 1, characterized in that The sensor also includes a moving wheel (5) arranged at the bottom.

8. The sensor according to claim 1, characterized in that The lift-off value L of the integrated signal transceiver component (3) is less than 1 mm.

9. A wind turbine tower defect detection method based on the sensor according to any one of claims 1 to 8, characterized in that: The method comprises: S1. Adsorbing the sensor according to any one of claims 1 to 8 onto the outer wall surface of the wind turbine tower by means of magnetic attraction; S2, a high-frequency short pulse current is passed through the integrated signal transceiver component (3), thereby exciting a high-frequency dynamic magnetic field (7) near the surface of the object to be measured; at the same time, the bar magnet (21) induces a static bias magnetic field (6) in the near-surface area; the high-frequency dynamic magnetic field (7) interacts with the static bias magnetic field (6), and based on the magnetostrictive mechanism, a surface wave (8) is excited, which propagates around the sensor; S3, when the surface wave (8) propagates and encounters a defect area, a reflected echo is formed, and the echo interacts with the static bias magnetic field (6), and the echo signal is received through the transceiver integrated signal component (3) based on the magnetostrictive inverse effect; S4. Control the movement of the sensor according to the preset sensor scanning path and scanning interval, repeat steps S2 and S3 until the whole circumference of the tower is scanned, and finally analyze and process the echo signal returned by the integrated signal transceiver component (3) to obtain the defect area analysis result.

10. The method according to claim 9, characterized in that: The wavelength of the surface wave (8) Satisfy the following: Among them, v R is the surface wave (8) phase velocity, v s is the shear wave velocity of the surface wave (8), v p is the shear wave velocity of the surface wave (8), and f is the excitation frequency of the surface wave (8).

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