CN111426918A - Non-contact basin-type insulator detection device based on laser ultrasound - Google Patents
Non-contact basin-type insulator detection device based on laser ultrasound Download PDFInfo
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- CN111426918A CN111426918A CN202010267610.3A CN202010267610A CN111426918A CN 111426918 A CN111426918 A CN 111426918A CN 202010267610 A CN202010267610 A CN 202010267610A CN 111426918 A CN111426918 A CN 111426918A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
- G01R31/1209—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing using acoustic measurements
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
- G01R31/1218—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing using optical methods; using charged particle, e.g. electron, beams or X-rays
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
- G01R31/1227—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials
- G01R31/1263—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials of solid or fluid materials, e.g. insulation films, bulk material; of semiconductors or LV electronic components or parts; of cable, line or wire insulation
- G01R31/1272—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials of solid or fluid materials, e.g. insulation films, bulk material; of semiconductors or LV electronic components or parts; of cable, line or wire insulation of cable, line or wire insulation, e.g. using partial discharge measurements
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Abstract
A laser ultrasonic non-contact type basin-type insulator nondestructive testing device comprises a laser excitation module, an electromagnetic ultrasonic receiving module, a control and synchronization module and a tomography module. The laser excitation module is connected with the control and synchronization module, the electromagnetic ultrasonic module is also connected with the control and synchronization module, and the electromagnetic ultrasonic receiving module is connected with the tomography module. The control and synchronization module firstly outputs a synchronization signal to enable the laser excitation module and the electromagnetic ultrasonic receiving module to start working, and the electromagnetic ultrasonic receiving module receives the ultrasonic signal and then outputs the ultrasonic signal to the tomography module to enable the tomography module to carry out imaging. The laser excitation module excites the basin-type insulator through pulse laser to enable the basin-type insulator to generate high-frequency ultrasound inside the basin-type insulator. The electromagnetic ultrasonic receiving module obtains echo signals generated by ultrasonic transmitted in the basin-type insulator by utilizing the Lorentz force effect of electromagnetic ultrasonic. The fault imaging module comprises a computer and realizes fault imaging of the basin-type insulator.
Description
Technical Field
The invention relates to a non-contact insulator detection device based on laser ultrasound.
Background
The basin-type insulator is used as a core component of a GIS (Gas Insulated Switchgear), and plays roles of supporting a conductor, isolating an air chamber and electrically insulating. Its presence distorts the GIS electric field distribution, especially at the triple junction. Statistical analysis shows that the basin-type insulator occupies a large proportion in GIS faults and is the weakest insulation link in the GIS, particularly when metal particle pollution, surface burrs, bulges and other defects exist in the GIS, flashover voltage is seriously reduced, insulation problems are one of important factors threatening safe operation of equipment, once insulation faults occur, the required maintenance time is much longer than AIS, a withstand voltage test needs to be carried out after repair, product interchangeability among GIS manufacturers is poor, and the compatibility of equipment maintenance, part replacement and type selection of extension engineering can be greatly disturbed.
Due to the compactness and complexity of the internal space structure of the GIS, the internal maintenance of the GIS is very difficult, the transmission of the fault in the internal limited space also influences the performance of non-fault elements, and the fault is caused in a larger range, the average power failure time required for maintaining the fault of the GIS equipment is longer than that of the maintenance of a conventional substation, and the economic loss is larger. Therefore, if early signs of a latent insulation fault can be identified and the insulation state can be accurately judged, an optimal maintenance plan can be arranged before the GIS equipment is about to break down, and the problem that the breakdown causes greater economic loss is avoided. The existing detection methods mainly comprise a pulse current method, an ultrasonic method, a chemical detection method and the like, the pulse current method and the chemical detection method cannot carry out online detection, and the ultrasonic method has the potential of online detection. Therefore, a non-contact on-line detection device is urgently needed.
Laser ultrasound has a certain potential in basin-type insulator detection as a non-contact online detection technology, but the existing laser ultrasound detection technology directly excites a detected target body through laser, ultrasonic waves are generated in the detected target body due to thermoelastic or ablation effects, and the photoacoustic conversion efficiency of the basin-type insulator is not high, so that the detection sensitivity is reduced.
Disclosure of Invention
The invention aims to solve the problems that the existing basin-type insulator cannot be detected on line or is low in on-line detection sensitivity, and provides a non-contact basin-type insulator detection device based on laser ultrasound.
The detection device comprises a laser excitation module, an electromagnetic ultrasonic receiving module, a control and synchronization module and a tomography module; the laser excitation module and the electromagnetic ultrasonic module are both connected with the control and synchronization module, and the electromagnetic ultrasonic receiving module is connected with the tomography module; the control and synchronization module firstly outputs a synchronization signal to enable the laser excitation module and the electromagnetic ultrasonic receiving module to start working, and the electromagnetic ultrasonic receiving module receives an ultrasonic signal and then outputs the ultrasonic signal to the tomography module; the laser excitation module excites the basin-type insulator through pulse laser to generate high-frequency ultrasound inside the basin-type insulator; the electromagnetic ultrasonic receiving module acquires echo signals generated by ultrasonic transmitted in the basin-type insulator by utilizing the Lorentz force effect of electromagnetic ultrasonic;
the fault imaging module comprises a computer (9) for realizing fault imaging of the basin-type insulator (4);
the laser excitation module comprises a pulse laser (1), a laser collimation system (2) and a convex lens (3); the laser collimation system is positioned between the pulse laser (1) and the convex lens (3); the laser beam emitted by the pulse laser (1) is used as a collimated baseline and is coaxial with the main optical axis of the convex lens (3); the pulse laser (1) emits pulse laser under the control of the control and synchronization module, and the pulse laser is focused on the surface of the basin-type insulator (4) through the laser collimation system (2) and the convex lens (3).
The electromagnetic ultrasonic receiving module comprises an electromagnetic ultrasonic transducer (6) and a signal detection processing system (8), the electromagnetic ultrasonic transducer (6) is connected with the signal detection processing system (8), and the signal detection processing system (8) is connected with a signal generator (7) of the control and synchronization module;
the control and synchronization module comprises a three-dimensional scanning platform (5) and a signal generator (7), the signal generator (7) synchronously controls the laser excitation module and the electromagnetic ultrasonic receiving module, and the three-dimensional scanning platform (5) controls the laser excitation module and the electromagnetic ultrasonic receiving module to realize circumferential scanning of the basin-type insulator (4);
the fault imaging module comprises a computer (9) and realizes fault imaging of the basin-type insulator (4).
Optionally, the electromagnetic ultrasonic transducer (6) consists of a magnet and an exciting coil, and has two structural forms of a directional electromagnetic ultrasonic transducer and an omnidirectional ultrasonic transducer.
Optionally, the directional electromagnetic ultrasonic transducer is composed of two parallel square magnet permanent magnets 1a1 and 2a2 with equal size, the two magnets have opposite magnetic poles and opposite polarities; the magnetic material of the magnet is NdFeb, and the exciting coil is positioned below the magnet and is coaxial and tightly connected with the magnet; the exciting coil is a zigzag coil A3, and is designed by PCB flexible processing for the excitation coil with a folding structure.
Optionally, the omnidirectional ultrasonic transducer is composed of a columnar permanent magnet B2 and a ring-shaped magnet B1 surrounding the columnar permanent magnet B2, and the magnetic poles of the ring-shaped permanent magnet B1 are opposite; the columnar permanent magnet B2 and the annular permanent magnet B1 are placed compactly, or epoxy resin is filled between the columnar permanent magnet B2 and the annular permanent magnet B1; the columnar permanent magnet B2 and the annular permanent magnet B1 are equal in height and cross-sectional area; the excitation coil of the omnidirectional ultrasonic transducer adopts a double-turn coil structure, the double-turn coil is divided into an inner-turn coil and an outer-turn coil, the inner-turn coil and the outer-turn coil are coaxial, the outer diameter of the outer-turn coil is larger than the maximum radius of the annular permanent magnet B1, the outer diameter of the inner-turn coil is slightly larger than the diameter of the columnar permanent magnet B2, and the outer diameter of the outer-turn coil is slightly larger than the outer diameter of the annular permanent magnet B1.
Optionally, a signal generator (7) of the control and synchronization module transmits a synchronization signal to the pulse laser (1), the pulse laser (1) receives the synchronization signal and then transmits pulse laser, the laser beam is collimated by the laser collimation system (2), a focused laser beam is generated under the focusing action of the convex lens (3), the focused laser beam irradiates the surface of the tested basin-type insulator (4), the basin-type insulator (4) is located in the scanning range of the pulse laser (1) and the electromagnetic ultrasonic transducer (6), and the electromagnetic ultrasonic transducer (6) receives an ultrasonic echo signal; the electromagnetic ultrasonic transducer (6) receives ultrasonic echo signals, the ultrasonic echo signals are converted into electric signals, the electric signals received by the electromagnetic ultrasonic transducer (6) are amplified and filtered by the signal detection processing system through the signal detection processing system (8), the electric signals are collected by the data acquisition system and stored in the computer (9), all the echo signals in the scanning process are stored in the computer (9), and a tomography image is reconstructed by adopting a filtering back projection and iterative reconstruction combined algorithm.
Optionally, the three-dimensional scanning platform (5) controls the electromagnetic ultrasonic transducer (6) and the laser excitation module C1, and the circular scanning detection of the basin-type insulator is performed by adopting a laser excitation scanning mode: firstly, an electromagnetic ultrasonic transducer (6) is fixed, a first dimension of a three-dimensional scanning platform (5) controls a circular scanner to realize the circular scanning of a fault of a basin-type insulator (4) by a laser excitation module C1, then a second dimension of the three-dimensional scanning platform controls another circular scanner to realize the circular movement of one step length of the electromagnetic ultrasonic transducer (6), then the movement of the electromagnetic ultrasonic transducer (6) is stopped, the first dimension of the three-dimensional scanning platform controls the circular scanner to realize the circular scanning of the same fault of the basin-type insulator (4) by the laser excitation module C1, and so on, the circular scanning of the same fault is completed, and finally the position movement of the next fault of the basin-type insulator (4) is realized by the third dimension of the three-dimensional scanning platform.
Optionally, the three-dimensional scanning platform (5) controls the electromagnetic ultrasonic transducer (6) and the laser excitation module C1, and performs circumferential scanning detection on the disc insulator by using an electromagnetic ultrasonic detection scanning mode: firstly fixing a laser excitation module C1, controlling a circular scanner by utilizing a first dimension of a three-dimensional scanning platform to realize the circular scanning of one fault of the basin-type insulator (4) by an electromagnetic ultrasonic transducer (6), then controlling another circular scanner by utilizing a second dimension of the three-dimensional scanning platform (5) to control a laser excitation module C1 to move the laser excitation module by one step length, fixing a laser excitation module C1 again, controlling the circular scanner by utilizing the first dimension of the three-dimensional scanning platform (5) to realize the circular scanning of the same fault of the basin-type insulator (4) by the electromagnetic ultrasonic transducer (6) again, repeating the steps to complete the circular scanning of the same fault, and finally realizing the position movement of the next fault of the basin-type insulator (4) by utilizing the third dimension of the three-dimensional scanning platform (5).
The non-contact type detection device for the basin-type insulator based on the laser ultrasound can realize the non-contact type detection of the basin-type insulator.
Drawings
FIG. 1 is a schematic diagram of a non-contact basin-type insulator detection device based on laser ultrasound according to the present invention,
in the figure: the system comprises a pulse laser 1, a laser collimation system 2, a convex lens 3, a basin-type insulator 4, a three-dimensional scanning platform 5, an electromagnetic ultrasonic transducer 6, a signal generator 7, a signal detection processing system 8 and a computer 9;
figure 2 the present invention is directed to an electromagnetic ultrasonic transducer structure,
in the figure: a1 permanent magnet 1, a2 permanent magnet 2, A3: a meander coil, a 4-basin insulator;
figure 3a an omnidirectional electromagnetic ultrasound transducer structure of the reversed double-turn coil structure of the invention,
in the figure: b1 ring magnet, B2 column magnet, B4 reverse double-turn coil structure;
figure 3b shows an omnidirectional electromagnetic ultrasound transducer structure with a homodromous double-turn coil structure according to the invention,
in the figure: b1 ring magnet, B2 column magnet, B5 homodromous double-turn coil structure;
FIG. 4a laser excitation scanning mode of the present invention;
figure 4b electromagnetic ultrasound inspection scanning mode of the invention,
in the figure: 4 basin insulators, 6 electromagnetic ultrasonic transducers, C1 laser excitation module.
Detailed Description
The invention aims to solve the problems that the existing basin-type insulator cannot be detected on line or is low in on-line detection sensitivity, and provides a non-contact basin-type insulator detection device based on laser ultrasound.
The invention discloses a non-contact basin-type insulator detection device based on laser ultrasound. The laser excitation module is connected with the control and synchronization module, the electromagnetic ultrasonic module is also connected with the control and synchronization module, and the electromagnetic ultrasonic receiving module is connected with the tomography module. The control and synchronization module firstly outputs a synchronization signal to enable the laser excitation module and the electromagnetic ultrasonic receiving module to start working, and the electromagnetic ultrasonic receiving module receives the ultrasonic signal and then outputs the ultrasonic signal to the tomography module. The laser excitation module emits pulse laser to excite the basin-type insulator to generate high-frequency ultrasound inside the basin-type insulator. The electromagnetic ultrasonic receiving module obtains echo signals generated by ultrasonic transmitted in the basin-type insulator by utilizing the Lorentz force effect of electromagnetic ultrasonic. The control and synchronization module comprises a three-dimensional scanning platform and a signal generator, the signal generator synchronously controls the laser excitation module and the electromagnetic ultrasonic receiving module, and the three-dimensional scanning platform controls the laser excitation module and the electromagnetic ultrasonic receiving module to realize circumferential scanning of the basin-type insulator to be detected. The fault imaging module comprises a computer and realizes fault imaging of the basin-type insulator.
The laser excitation module comprises a pulse laser, a laser collimation system and a convex lens. The laser collimation system is positioned between the pulse laser and the convex lens. The laser beam emitted by the pulse laser is coaxial with the main optical axis of the convex lens as a collimated baseline. The pulse laser emits pulse laser under the control of the control and synchronization module, and the pulse laser is collimated by the laser collimation system and focused on the surface of the basin-type insulator through the convex lens. The wavelength of the pulse laser can be 532nm green light or frequency doubling light 1064nm, the pulse width is less than 20ns, and the laser can be Nd: YAG laser, which may be femtosecond laser.
The electromagnetic ultrasonic receiving module comprises an electromagnetic ultrasonic transducer and a signal detection processing system. The electromagnetic ultrasonic transducer is connected with a signal detection processing system, and the signal detection processing system is connected with a signal generator of the control and synchronization module. The electromagnetic ultrasonic transducer is composed of a magnet and an exciting coil, and is different from the traditional electromagnetic ultrasonic transducer, and the electromagnetic ultrasonic transducer is a directional electromagnetic ultrasonic transducer or an omnidirectional electromagnetic ultrasonic transducer. The directional electromagnetic ultrasonic transducer consists of two parallel square magnets with the same size, wherein the magnetic poles of the two magnets are opposite and the polarities of the two magnets are opposite. The exciting coil is arranged below the magnet and is adhered with the magnet to form the electromagnetic ultrasonic transducer, and the exciting coil is designed by utilizing PCB flexible processing and is of a folding structure. The magnetic material of the magnet is NdFeb. The omnidirectional ultrasonic transducer consists of a columnar permanent magnet and a ring magnet surrounding the columnar permanent magnet, wherein the magnetic poles of the two magnets are opposite. The columnar permanent magnet and the annular permanent magnet can be compactly placed, epoxy resin can be filled between the two magnets, the height of the columnar magnet and the height of the annular magnet are equal, and the cross-sectional area of the columnar magnet and the cross-sectional area of the annular magnet are equal. The exciting coil of the omnidirectional ultrasonic transducer is a double-turn coil, and the outer diameter of the double-turn coil is slightly larger than that of the annular permanent magnet. The double-turn coil is divided into an inner-turn coil and an outer-turn coil, the current directions of the inner-turn coil and the outer-turn coil can be the same or opposite, the outer diameter of the inner-turn coil is slightly larger than the diameter of the columnar magnet, and the outer diameter of the outer-turn coil is slightly larger than the outer diameter of the annular magnet.
The control and synchronization module controls a pulse laser and an electromagnetic ultrasonic receiving module of the laser excitation module. And a signal generator of the control and synchronization module sends a synchronization signal to the pulse laser and a signal processing and detecting system of the electromagnetic ultrasonic receiving module, so that the synchronization of the laser ultrasonic excitation and the electromagnetic ultrasonic receiving module is realized. The three-dimensional scanning platform controls the electromagnetic ultrasonic transducer and the laser excitation module to scan, and circumferential scanning detection of the basin-type insulator is achieved. The circular scanning detection comprises two modes, one mode is that firstly, the electromagnetic ultrasonic transducer is fixed, the circular scanning of the laser excitation module on the basin-type insulator is realized by using the three-dimensional scanning platform, then, the electromagnetic ultrasonic transducer moves by one step length, the electromagnetic ultrasonic transducer is fixed again, the circular scanning of the laser excitation module on the fault of the basin-type insulator is realized by using the three-dimensional scanning platform, and the rest is done by analogy, and the whole scanning is completed. The other mode is that the laser excitation module is fixed firstly, the three-dimensional scanning platform is used for realizing the circumferential scanning of the electromagnetic ultrasonic transducer on the basin-type insulator, then the laser excitation module moves by one step length, the laser excitation module is fixed again, the three-dimensional scanning platform is used for realizing the circumferential scanning of the electromagnetic ultrasonic transducer on the basin-type insulator, and the rest is done by analogy to complete the whole scanning.
The computer is used for storing all echo signals in the scanning process, and a tomography image is reconstructed by adopting a filtering back projection and iterative reconstruction combined algorithm, wherein the reconstruction process is simply described as follows: firstly, reconstructing a tomography image by using a filtering back-projection algorithm, then calculating an actual ultrasonic propagation time vector on each path according to a standard model by using the acquired ultrasonic signal propagation path matrix excited and detected each time, and performing error correction on the reconstructed image to obtain an actual tomography image.
The non-contact basin-type insulator nondestructive testing device adopts laser ultrasonic to excite the surface of the basin-type insulator, receives an echo signal by using a non-contact electromagnetic ultrasonic transducer by means of an ultrasonic echo method, realizes the tomography of the circumferential surface of the basin-type insulator in a laser scanning mode, and finally analyzes the received echo ultrasonic signal so as to realize the tomography imaging of the basin-type insulator.
The specific process is as follows:
firstly, a signal generator of a synchronous control system transmits a synchronous signal to a pulse laser, the pulse laser transmits pulse laser after receiving the synchronous signal, the laser beam is collimated by a laser collimation system, a focused laser beam is formed under the focusing action of a convex lens, and the focused laser beam irradiates the surface of the basin-type insulator to be measured. The basin-type insulator is positioned in the scanning range of the pulse laser and the electromagnetic ultrasonic transducer. Due to the photoacoustic effect, the acoustic signal generated on the basin insulator is received by the detection probe. By adjusting the distance between the convex lens and the basin-type insulator, the size of a light spot irradiated on the surface of the basin-type insulator is changed, namely the size of a focused focal spot is changed, the smaller the focused focal spot is, the more concentrated the energy is, and the stronger the intensity of the generated ultrasonic signal is. The electromagnetic ultrasonic transducer receives the ultrasonic echo signal, converts the ultrasonic signal into an electric signal, and the electric signal is amplified and filtered by the signal detection processing system, collected by the data collection system and stored in the computer. And the computer stores all echo signals in the scanning process and reconstructs a tomography image by adopting a filtering back projection and iterative reconstruction combined algorithm.
The invention is further described below with reference to the accompanying drawings and the detailed description.
As shown in figure 1, the laser ultrasonic non-contact type basin-type insulator detection device comprises a laser excitation module, an electromagnetic ultrasonic receiving module, a control and synchronization module and a tomography module. The laser excitation module is connected with the control and synchronization module, the electromagnetic ultrasonic module is also connected with the control and synchronization module, and the electromagnetic ultrasonic receiving module is connected with the tomography module. The control and synchronization module firstly outputs a synchronization signal to enable the laser excitation module and the electromagnetic ultrasonic receiving module to start working, and the electromagnetic ultrasonic receiving module receives the ultrasonic signal and then outputs the ultrasonic signal to the tomography module to enable the tomography module to carry out imaging. The laser excitation module excites the basin-type insulator through pulse laser to enable the basin-type insulator to generate high-frequency ultrasound inside the basin-type insulator. The electromagnetic ultrasonic receiving module obtains echo signals generated by ultrasonic transmitted in the basin-type insulator by utilizing the Lorentz force effect of electromagnetic ultrasonic.
The control and synchronization module comprises a three-dimensional scanning platform 5 and a signal generator 7, the signal generator synchronously controls the laser excitation module and the electromagnetic ultrasonic receiving module, and the three-dimensional scanning platform 5 controls the laser excitation module and the electromagnetic ultrasonic receiving module to realize the fault scanning of the basin-type insulator 4.
The tomography module comprises a computer 9, and tomography of the basin-type insulator 4 is realized.
The laser excitation module comprises a pulse laser 1, a laser collimation system 2 and a convex lens 3. The laser collimation system is positioned between the pulse laser and the convex lens. The laser beam emitted by the pulse laser is coaxial with the main optical axis of the convex lens 3 as a collimated baseline. The pulse laser 1 emits pulse laser under the control of the control and synchronization module, and the pulse laser is focused on the surface of the basin-type insulator 4 through the laser collimation system 2 and the convex lens 3. The wavelength of the pulse laser 1 can be 532nm green light, or frequency doubling light 1064nm, the pulse width is less than 20ns, and the laser can be Nd: YAG laser, which may be femtosecond laser.
As shown in fig. 2 and fig. 3, the electromagnetic ultrasonic receiving module includes an electromagnetic ultrasonic transducer 6 and a signal detection processing system 8, the electromagnetic ultrasonic transducer 6 is connected to the signal detection processing system 8, and the signal detection processing system 8 is connected to the signal generator 7 of the control and synchronization module. The electromagnetic ultrasonic transducer 6 is composed of a magnet and an exciting coil. The electromagnetic ultrasonic transducer 6 of the present invention has two structures, one is the electromagnetic ultrasonic transducer 6 of the directional type shown in fig. 2, and the other is the ultrasonic transducer 6 of the omnidirectional type shown in fig. 3a and 3 b. The directional electromagnetic ultrasonic transducer 6 is composed of two parallel square magnet permanent magnets 1A1 and 2A2 with the same size, the magnetic poles of the two magnets are opposite, and the polarities of the two magnets are opposite. The magnetic material of the magnet is NdFeb; the exciting coil is positioned below the magnet and is coaxial and closely connected with the magnet. An excitation coil of the directional electromagnetic ultrasonic transducer is a zigzag coil A3 and is designed by PCB flexible processing; meander coil a3 is a meander structure excitation coil. The omnidirectional type ultrasonic transducer is composed of a columnar permanent magnet B2 and a ring magnet B1 surrounding it, the poles of the columnar permanent magnet B2 and the ring magnet B1 surrounding it being opposed. The columnar permanent magnet B2 and the annular permanent magnet B1 can be placed compactly, epoxy resin can be filled between the two magnets, and the columnar permanent magnet B2 and the annular permanent magnet B1 are equal in height and cross-sectional area. The exciting coil of the omnidirectional ultrasonic transducer adopts a double-turn coil structure, the double-turn coil is divided into an inner-turn coil and an outer-turn coil, the inner-turn coil and the outer-turn coil are coaxial, the current directions of the inner-turn coil and the outer-turn coil can be the same or opposite, wherein, a reverse double-turn coil structure is shown in figure 3a, a same-direction double-turn coil structure is shown in figure 3B, and the outer diameter of the outer-turn coil of the double-turn coil is larger than the maximum radius of the annular permanent magnet B1; the outer diameter of the inner turn coil of the double-turn coil is slightly larger than the diameter of the columnar permanent magnet B2, and the outer diameter of the outer turn coil is slightly larger than the outer diameter of the annular permanent magnet B1.
The control and synchronization module controls a pulse laser and an electromagnetic ultrasonic receiving module of the laser excitation module. And a signal generator of the control and synchronization module sends a synchronization signal to the pulse laser 1, a signal processing and detecting system 8 of the electromagnetic ultrasonic receiving module and the three-dimensional scanning platform 5, so that the synchronization of the laser ultrasonic excitation and the electromagnetic ultrasonic receiving module is realized. The three-dimensional scanning platform 5 controls the electromagnetic ultrasonic transducer 6 and the laser excitation module to scan, and the circumferential scanning detection of the basin-type insulator is realized.
The circular scanning detection comprises two modes, fig. 4a shows a laser excitation scanning mode, firstly, the electromagnetic ultrasonic transducer 6 is fixed, the first dimension of the three-dimensional scanning platform 5 controls a circular scanner to realize the circular scanning of the laser excitation module C1 on a fault of the basin-type insulator 4, and then the second dimension of the three-dimensional scanning platform controls another circular scanner to realize the circular movement of the electromagnetic ultrasonic transducer 6 by one step length; and then stopping moving the electromagnetic ultrasonic transducer 6, controlling a circular scanner by using the first dimension of the three-dimensional scanning platform to realize the circular scanning of the laser excitation module C1 on the same fault of the basin-type insulator 4, repeating the operation in the same way to finish the circular scanning of the same fault, and finally realizing the position movement of the next fault of the basin-type insulator 4 by using the third dimension of the three-dimensional scanning platform. Fig. 4b shows another mode: and (3) an electromagnetic ultrasonic detection scanning mode. Firstly fixing a laser excitation module C1, controlling a circular scanner by utilizing a first dimension of a three-dimensional scanning platform to realize the circular scanning of the electromagnetic ultrasonic transducer 6 on a fault of the basin-type insulator 4, then controlling another circular scanner by utilizing a second dimension of the three-dimensional scanning platform to realize the control on the laser excitation module C1, moving the laser excitation module C3526 by one step length, fixing the laser excitation module C1 again, controlling the circular scanner by utilizing the first dimension of the three-dimensional scanning platform to realize the circular scanning of the electromagnetic ultrasonic transducer 6 on the same fault of the basin-type insulator 4 again, repeating the steps, completing the circular scanning of the same fault, and finally realizing the position movement of the next fault of the basin-type insulator 4 by utilizing the third dimension of the three-dimensional scanning platform.
The computer is used for storing all echo signals in the scanning process, and can adopt a filtering back projection and iterative reconstruction combined algorithm to reconstruct a tomography image, wherein the reconstruction process is simply described as follows:
firstly, a tomography image is reconstructed by using a filtering back-projection algorithm, and then the actual vector of ultrasonic propagation time on each path is calculated by using the acquired ultrasonic signal propagation path matrix excited and detected each time according to a standard model to correct the error of the reconstructed image, so that the actual tomography image is obtained.
The surface of the basin-type insulator 4 is excited by the pulse laser 1, the non-contact electromagnetic ultrasonic transducer 6 is used for receiving echo signals by means of an ultrasonic echo method, the tomography of the circumference of the surface of the basin-type insulator 4 is realized by a scanning detection mode, and finally the echo ultrasonic signals received by the electromagnetic ultrasonic transducer 6 are analyzed so as to realize the tomography imaging of the basin-type insulator 4. The method comprises the following specific steps:
firstly, a signal generator 7 of a control and synchronization module transmits a synchronization signal to a pulse laser 1, the pulse laser 1 transmits pulse laser after receiving the synchronization signal, the laser beam is collimated by a laser collimation system 2 and generates a focused laser beam under the focusing action of a convex lens 3, the focused laser beam irradiates the surface of a basin-type insulator 4 to be detected, the basin-type insulator 4 is positioned in the scanning range of the pulse laser 1 and an electromagnetic ultrasonic transducer 6, and due to the photoacoustic effect, an acoustic wave signal is generated in the basin-type insulator 4, and the acoustic wave echo signal is received by a detection probe. By adjusting the distance between the convex lens 3 and the basin-shaped insulator 4, the size of the light spot irradiated on the surface of the basin-shaped insulator, namely the size of the focused focal spot, is changed. The ultrasonic echo signal is received by the electromagnetic ultrasonic transducer 6 at the receiving end, the ultrasonic echo signal generates an electric signal, the electric signal received by the electromagnetic ultrasonic transducer 6 is amplified and filtered by the signal detection processing system 8, and is acquired by the data acquisition system and stored in the computer 9.
The non-contact type detection device for the basin-type insulator based on the laser ultrasound can realize the non-contact type detection of the basin-type insulator.
Claims (7)
1. A non-contact basin-type insulator detection device based on laser ultrasound is characterized in that the detection device comprises a laser excitation module, an electromagnetic ultrasound receiving module, a control and synchronization module and a tomography module; the laser excitation module and the electromagnetic ultrasonic module are both connected with the control and synchronization module, and the electromagnetic ultrasonic receiving module is connected with the tomography module; the control and synchronization module firstly outputs a synchronization signal to enable the laser excitation module and the electromagnetic ultrasonic receiving module to start working, and the electromagnetic ultrasonic receiving module receives an ultrasonic signal and then outputs the ultrasonic signal to the tomography module; the laser excitation module excites the basin-type insulator through pulse laser to generate high-frequency ultrasound inside the basin-type insulator; the electromagnetic ultrasonic receiving module acquires echo signals generated by ultrasonic transmitted in the basin-type insulator by utilizing the Lorentz force effect of electromagnetic ultrasonic;
the fault imaging module comprises a computer (9) for realizing fault imaging of the basin-type insulator (4);
the laser excitation module comprises a pulse laser (1), a laser collimation system (2) and a convex lens (3); the laser collimation system is positioned between the pulse laser (1) and the convex lens (3); the laser beam emitted by the pulse laser (1) is used as a collimated baseline and is coaxial with the main optical axis of the convex lens (3); the pulse laser (1) emits pulse laser under the control of the control and synchronization module, and the pulse laser is focused on the surface of the basin-type insulator (4) through the laser collimation system (2) and the convex lens (3).
The electromagnetic ultrasonic receiving module comprises an electromagnetic ultrasonic transducer (6) and a signal detection processing system (8), the electromagnetic ultrasonic transducer (6) is connected with the signal detection processing system (8), and the signal detection processing system (8) is connected with a signal generator (7) of the control and synchronization module;
the control and synchronization module comprises a three-dimensional scanning platform (5) and a signal generator (7), the signal generator (7) synchronously controls the laser excitation module and the electromagnetic ultrasonic receiving module, and the three-dimensional scanning platform (5) controls the laser excitation module and the electromagnetic ultrasonic receiving module to realize circumferential scanning of the basin-type insulator (4);
the fault imaging module comprises a computer (9) and realizes fault imaging of the basin-type insulator (4).
2. The laser-based ultrasonic non-contact basin insulator testing device according to claim 1, wherein said electromagnetic ultrasonic transducer (6) is composed of a magnet and an excitation coil, and has two structural forms of a directional electromagnetic ultrasonic transducer and an omnidirectional ultrasonic transducer.
3. The laser-based ultrasonic non-contact basin insulator detection device according to claim 2, wherein the directional electromagnetic ultrasonic transducer is composed of two parallel square magnet permanent magnets 1A1 and 2A2 with equal size, the two magnets have opposite magnetic poles and opposite polarities; the magnetic material of the magnet is NdFeb, and the exciting coil is positioned below the magnet and is coaxial and tightly connected with the magnet; the exciting coil is a zigzag coil A3, and is designed by PCB flexible processing for the excitation coil with a folding structure.
4. The laser-based ultrasonic non-contact type basin insulator testing device according to claim 2, wherein said omnidirectional ultrasonic transducer is composed of a cylindrical permanent magnet B2 and a ring magnet B1 surrounding it, the poles of the cylindrical permanent magnet B2 and the ring magnet B1 are opposite; the columnar permanent magnet B2 and the annular permanent magnet B1 are placed compactly, or epoxy resin is filled between the columnar permanent magnet B2 and the annular permanent magnet B1; the columnar permanent magnet B2 and the annular permanent magnet B1 are equal in height and cross-sectional area; the excitation coil of the omnidirectional ultrasonic transducer adopts a double-turn coil structure, the double-turn coil is divided into an inner-turn coil and an outer-turn coil, the inner-turn coil and the outer-turn coil are coaxial, the outer diameter of the outer-turn coil is larger than the maximum radius of the annular permanent magnet B1, the outer diameter of the inner-turn coil is slightly larger than the diameter of the columnar permanent magnet B2, and the outer diameter of the outer-turn coil is slightly larger than the outer diameter of the annular permanent magnet B1.
5. The laser-based ultrasonic non-contact type basin insulator detection device according to claim 1, wherein the signal generator (7) of the control and synchronization module transmits a synchronization signal to the pulse laser (1), the pulse laser (1) transmits pulse laser after receiving the synchronization signal, the laser beam is collimated by the laser collimation system (2), a focused laser beam is generated under the focusing action of the convex lens (3), the focused laser beam irradiates the surface of the basin insulator (4) to be detected, the basin insulator (4) is located in the scanning range of the pulse laser (1) and the electromagnetic ultrasonic transducer (6), and the electromagnetic ultrasonic transducer (6) receives an ultrasonic echo signal; the electromagnetic ultrasonic transducer (6) receives ultrasonic echo signals, the ultrasonic echo signals are converted into electric signals, the electric signals received by the electromagnetic ultrasonic transducer (6) are amplified and filtered by the signal detection processing system through the signal detection processing system (8), the electric signals are collected by the data acquisition system and stored in the computer (9), all the echo signals in the scanning process are stored in the computer (9), and a tomography image is reconstructed by adopting a filtering back projection and iterative reconstruction combined algorithm.
6. The laser-based ultrasonic non-contact type basin insulator detection device according to claim 1, characterized in that the three-dimensional scanning platform (5) controls the electromagnetic ultrasonic transducer (6) and the laser excitation module C1, and the basin insulator is circumferentially scanned and detected by adopting a laser excitation scanning mode: firstly, an electromagnetic ultrasonic transducer (6) is fixed, a first dimension of a three-dimensional scanning platform (5) controls a circular scanner to realize the circular scanning of a fault of a basin-type insulator (4) by a laser excitation module C1, then a second dimension of the three-dimensional scanning platform controls another circular scanner to realize the circular movement of one step length of the electromagnetic ultrasonic transducer (6), then the movement of the electromagnetic ultrasonic transducer (6) is stopped, the first dimension of the three-dimensional scanning platform controls the circular scanner to realize the circular scanning of the same fault of the basin-type insulator (4) by the laser excitation module C1, and so on, the circular scanning of the same fault is completed, and finally the position movement of the next fault of the basin-type insulator (4) is realized by the third dimension of the three-dimensional scanning platform.
7. The laser-ultrasonic-based non-contact type basin insulator detection device according to claim 1, characterized in that the three-dimensional scanning platform (5) controls the electromagnetic ultrasonic transducer (6) and the laser excitation module C1, and the basin insulator is detected by scanning circumferentially in an electromagnetic ultrasonic detection scanning mode: firstly fixing a laser excitation module C1, controlling a circular scanner by utilizing a first dimension of a three-dimensional scanning platform to realize the circular scanning of one fault of the basin-type insulator (4) by an electromagnetic ultrasonic transducer (6), then controlling another circular scanner by utilizing a second dimension of the three-dimensional scanning platform (5) to control a laser excitation module C1 to move the laser excitation module by one step length, fixing a laser excitation module C1 again, controlling the circular scanner by utilizing the first dimension of the three-dimensional scanning platform (5) to realize the circular scanning of the same fault of the basin-type insulator (4) by the electromagnetic ultrasonic transducer (6) again, repeating the steps to complete the circular scanning of the same fault, and finally realizing the position movement of the next fault of the basin-type insulator (4) by utilizing the third dimension of the three-dimensional scanning platform (5).
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