Built-in acoustic-electric combined sensor of transformer and partial discharge detection method

Abstract

The invention provides a built-in acoustic-electric combined sensor of a transformer and a partial discharge detection method. The sensor includes: a mounting unit; the ultrahigh frequency sensing unit is arranged on the mounting unit; one end of the connecting rod is connected with the ultrahigh frequency sensing unit, and the other end is provided with an angle adjusting unit; the optical fiber ultrasonic sensing unit is arranged on the angle adjusting unit. The angle of the optical fiber ultrasonic sensing unit is adjusted through the angle adjusting unit, the detection range of the sensor is enlarged, or the detection angle is adjusted, so that the optimal angle is selected for detection, the problem that detection data is inaccurate due to the fact that a fixed structure obtains single angle data is solved, the sensitivity of a detection system is enhanced, and the detection precision is improved. According to the invention, the detection accuracy is ensured, the partial discharge measurement advantages of the ultrahigh frequency sensing unit and the optical fiber ultrasonic sensing unit are combined, the simultaneous acquisition of ultrahigh frequency signals and optical fiber ultrasonic signals is realized through the joint detection of acoustic and electrical signals, and the problem that the sensitivity of single partial discharge detection is limited is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of partial discharge detection of power transformers, and in particular to a transformer built-in acoustic-electric combined sensor and a partial discharge detection method. Background Art

[0002] Power transformers are key equipment for power transmission and distribution in power systems. Large transformers are expensive, and their safe and stable operation is crucial to ensuring the safety of the power grid. However, transformer insulation materials will age over time, leading to partial discharge problems, which will have a significant negative impact on the safety and stability of the transformer, and in turn pose a threat to the safe operation of the entire power grid. Therefore, transformer partial discharge detection is a vital task. By effectively diagnosing and identifying partial discharge problems inside the transformer, potential fault hazards can be eliminated in a timely manner to ensure the normal operation of the transformer and the stable power supply of the power grid.

[0003] At present, the methods used to diagnose the defect type of partial discharge in transformers usually use a single sensor for detection. However, this type of method can only obtain single information of ultra-high frequency, high frequency current or ultrasonic data, and it is difficult to perform multi-sensor joint synchronous detection data. Since the single data acquisition method cannot provide accurate defect type identification, the effectiveness of problem diagnosis and identification is limited. If these two sensors are used for detection at the same time, they need to be installed in different positions respectively, resulting in complex sensor layout and high installation and maintenance costs. Due to the long distance between different sensors, it is difficult to achieve synchronous data collection and precise positioning, which affects the detection accuracy. Therefore, the combined acoustic and electrical sensing detection of partial discharge inside the transformer is of great significance.

[0004] In order to improve the detection accuracy, ultrasonic sensors and UHF sensors are preferably arranged inside the transformer, so the built-in sensors need to ensure insulation safety. However, both ultrasonic sensors and UHF sensors adopt a fixed structure, which does not cover all angles and can only obtain data from one angle, resulting in inaccurate detection data. Summary of the invention

[0005] In view of this, the present invention proposes a transformer built-in acoustic-electric combined sensor and a partial discharge detection method, aiming to solve the problem that the existing transformer internal partial discharge detection sensor is a fixed structure and can only obtain single angle data, resulting in inaccurate detection data.

[0006] On the one hand, the present invention proposes a transformer built-in acoustic-electric combined sensor, which includes: an installation unit, used to be installed on the transformer to be tested; an ultra-high frequency sensing unit, arranged on the installation unit, and used to detect the ultra-high frequency signal generated by local discharge in the transformer to be tested; a connecting rod, one end of which is connected to the ultra-high frequency sensing unit, and the other end is provided with an angle adjustment unit; a fiber optic ultrasonic sensing unit, arranged in the angle adjustment unit, and the angle adjustment unit is used to adjust the arrangement angle of the fiber optic ultrasonic sensing unit to obtain an optimal detection angle, so that the fiber optic ultrasonic sensing unit can detect the ultrasonic signal generated by local discharge in the transformer to be tested at the optimal detection angle, thereby monitoring the operating status of the transformer to be tested based on the ultra-high frequency signal and the ultrasonic signal.

[0007] Furthermore, in the above-mentioned transformer built-in acoustic-electric combined sensor, the piezoelectric self-energy extraction unit is connected to the angle adjustment unit, and the mounting unit is provided with a piezoelectric self-energy extraction unit, which is used to generate an electrical signal to power the angle adjustment unit when the mounting unit vibrates with the transformer to be tested and the vibration signal acts on the piezoelectric self-energy extraction unit.

[0008] Furthermore, in the above transformer built-in acoustic-electric combined sensor, the piezoelectric self-energy extraction unit is a cylindrical piezoelectric ceramic piece.

[0009] Furthermore, in the above-mentioned transformer built-in acoustic-electric combined sensor, the mounting unit includes: an insulating disk; a mounting disk, one side of the mounting disk is sealedly connected to the insulating disk; a flange disk is sealedly connected to the other side of the mounting disk, and the side of the insulating disk facing away from the mounting disk is sealedly connected to the side of the UHF sensing unit facing away from the connecting rod.

[0010] Furthermore, in the above transformer built-in acoustic-electric combined sensor, the connecting rod is a telescopic rod structure, which is used to adjust the position of the optical fiber ultrasonic sensing unit inside the transformer to be tested.

[0011] Furthermore, in the above transformer built-in acoustic-electric combined sensor, the connecting rod is hollow inside and is used for threading to achieve the lead-out of the optical fiber in the optical fiber ultrasonic sensing unit.

[0012] Furthermore, in the above transformer built-in acoustic-electric combined sensor, the optical fiber ultrasonic sensing unit is a sensor probe with a ring structure made by vacuum casting, and is connected to the angle adjustment unit in a detachable manner.

[0013] Furthermore, in the above-mentioned transformer built-in acoustic-electric combined sensor, the angle adjustment unit is connected to a control unit for receiving ultra-high frequency signals and ultrasonic signals, and controlling the angle adjustment unit based on the ultra-high frequency signals and ultrasonic signals, so as to control the angle adjustment unit to drive the optical fiber ultrasonic sensing unit to rotate to an optimal angle.

[0014] On the other hand, the present invention also proposes a partial discharge detection method, which includes the following steps: step S1, using a transformer built-in acoustic and electrical combined sensor to perform preliminary detection on the transformer to be tested, obtain the amplitude of the ultra-high frequency signal and the amplitude of the ultrasonic signal generated by the partial discharge in the transformer to be tested, and compare them with a first threshold and a second threshold respectively; step S2, when the amplitude of the ultra-high frequency signal is greater than the first threshold and / or the amplitude of the ultrasonic signal is greater than the second threshold, drive the optical fiber ultrasonic sensor unit to rotate through an angle adjustment unit, so that the optical fiber ultrasonic sensor unit rotates to each gear position in turn, and at each gear position , obtaining the amplitude of the ultrasonic signal generated by the partial discharge in the transformer to be tested; wherein the optical fiber ultrasonic sensing unit has multiple gears to correspond to different arrangement angles; step S3, when the amplitude of the ultrasonic signal in at least one gear is greater than the second threshold, comparing the amplitudes of the ultrasonic signals in each gear, and determining the gear with the largest ultrasonic signal amplitude as the optimal gear; step S4, driving the optical fiber ultrasonic sensing unit to rotate to the optimal gear through the angle adjustment unit, and performing periodic partial discharge detection of the transformer to be tested at the optimal gear, obtaining the ultra-high frequency signal and ultrasonic signal generated by the partial discharge in the transformer to be tested, so as to monitor the operating status of the transformer to be tested.

[0015] Furthermore, in the above partial discharge detection method, when the amplitude of the ultrasonic signal at each gear position is less than or less than the second threshold, the optical fiber ultrasonic sensing unit is driven to rotate to the initial gear position through the angle adjustment unit, and steps S1 and S2 are repeated.

[0016] The transformer built-in acoustic-electric combined sensor and partial discharge detection method provided by the present invention combine the partial discharge measurement advantages of the ultra-high frequency sensing unit and the optical fiber ultrasonic sensing unit, realize the simultaneous collection of ultra-high frequency signals and optical fiber ultrasonic signals through the joint detection of acoustic and electrical signals, and solve the problem of limited sensitivity of single partial discharge detection; adopt an embedded structure, the optical fiber ultrasonic sensing probe is located inside the transformer, which can improve the anti-interference ability, detection sensitivity and accuracy of defect positioning, the ultra-high frequency sensing unit and the optical fiber ultrasonic sensing unit can effectively detect the partial discharge generated inside the transformer and quickly capture the partial discharge signal, and compare the use of the optical fiber ultrasonic sensor and the ultra-high frequency sensor at the same time to perform detection at different positions, support the synchronous detection of the optical fiber ultrasonic signal and the ultra-high frequency signal, have good consistency, and can efficiently monitor the internal discharge of the transformer, discover latent defects, and diagnose defects. The degree of insulation damage under the action of the electric field can be determined, thereby effectively carrying out fault warning and improving the status maintenance level of the transformer; the optical fiber ring of the optical fiber ultrasonic sensor is made into a sensor probe by vacuum casting, and at the same time, the various parts of the combined sensor such as the mounting plate, the insulating plate, the ultra-high frequency sensing unit and the optical fiber ultrasonic sensing unit are sealed by sealing rings, and the combined sensor becomes one with the transformer after installation, has good sealing, and can ensure reliable operation under high pressure and high oil temperature environment; the angle of the optical fiber ultrasonic sensing unit is adjusted by the angle adjustment unit to increase the sensor detection range, or adjust the detection angle to select the optimal angle for detection, which solves the problem that the existing local discharge detection sensor inside the transformer is a fixed structure and can only obtain a single angle data, resulting in inaccurate detection data, enhances the sensitivity of the detection system, and ensures the accuracy of detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings: Figure 1 A schematic diagram of the structure of a transformer-built-in acoustic-electric combined sensor provided in an embodiment of the present invention; Figure 2 A schematic diagram of the structure of the connection between the optical fiber ultrasonic sensor unit and the angle adjustment unit provided in an embodiment of the present invention; Figure 3 A schematic diagram of the structure of a fiber optic ultrasonic sensor unit provided in an embodiment of the present invention; Figure 4 A flowchart of a partial discharge detection method provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0018] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present disclosure and to be able to fully convey the scope of the present disclosure to those skilled in the art. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features described in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0019] See also Figure 1 and Figure 2 , which shows the preferred structure of the transformer built-in acoustic-electric combined sensor provided by the embodiment of the present invention. As shown in the figure, the transformer built-in acoustic-electric combined sensor includes: an installation unit 1, a UHF sensor unit 2, a connecting rod 3, an angle adjustment unit 4, an optical fiber ultrasonic sensor unit 5, a piezoelectric self-energy extraction unit 6, and a control unit (not shown in the figure).

[0020] The mounting unit 1 is used to be mounted on the transformer 8 to be tested. Specifically, the mounting unit 1 can be fixedly mounted on the transformer 8 to be tested, so that the transformer built-in acoustic-electric combined sensor and the transformer 8 to be tested are installed as an integrated structure. In order to ensure the sealing between the transformer built-in acoustic-electric combined sensor and the transformer 8 to be tested, preferably, a sealing ring is provided between the mounting unit 1 and the transformer 8 to be tested, so that the transformer 8 to be tested has good sealing at the location where the sensor is installed, avoiding leakage and insulation problems, thereby ensuring that the sensor operates reliably under high pressure and high oil temperature environment.

[0021] The UHF sensing unit 2 is arranged on the mounting unit 1, and is used to detect the UHF signal generated by the partial discharge in the transformer 8 to be tested, that is, by receiving the UHF signal in the surrounding environment, detecting the partial discharge according to the spectrum of the signal, and obtaining the electromagnetic wave signal generated by the partial discharge. Specifically, the left side of the UHF sensing unit 2 is sealed and connected to the right side of the mounting unit 1, and in particular, a sealing ring can be provided between the two to seal the two, further avoiding leakage and insulation problems, and further ensuring the long-term stability and reliability of the sensor. Among them, the UHF sensing unit 2 can be an antenna vibrator, especially a structure combining a flat plate and a conical receiving antenna, which has the characteristics of high comprehensiveness, simple structure and convenient processing. The working bandwidth is 300MHz~1500MHz, the gain is 40dB, the noise factor NF≤3dB, the detection sensitivity is not more than 2V / m, the dynamic detection range is not less than 60dB, the time deviation of different detection channels is <1μs, the amplification band of the RF amplifier used covers 2kHz~2GHz, and the amplifier gain within the frequency band is>30dB. In this embodiment, the UHF sensing unit 2 can be placed inside the transformer 8 to be tested, One end of the connecting rod 3 (such as Figure 1 The left end shown in FIG. 1 is connected to the UHF sensor unit 2, and the other end (as shown in FIG. Figure 2 The right end of the connecting rod 3 is provided with an angle adjustment unit 4. Specifically, the connecting rod 3 can be a support rod to support the angle adjustment unit 4 and the optical fiber ultrasonic sensor unit 5, so that the optical fiber ultrasonic sensor unit 5 is supported inside the transformer 8 to be tested. In this embodiment, the left end of the connecting rod 3 is fixedly connected to the UHF sensor unit 2, and the two are sealed and sealed, and a sealing ring can be provided for sealing; the right end of the connecting rod 3 is fixedly connected to the angle adjustment unit 4, and the two are sealed and sealed, and a sealing ring can be provided for sealing.

[0022] The optical fiber ultrasonic sensor unit 5 is arranged in the angle adjustment unit 4, and the angle adjustment unit 4 is used to adjust the arrangement angle of the optical fiber ultrasonic sensor unit 5 to obtain the optimal detection angle, so that the optical fiber ultrasonic sensor unit 5 can detect the ultrasonic signal generated by the partial discharge in the transformer 8 to be tested at the optimal detection angle, thereby monitoring the operating state of the transformer 8 to be tested based on the ultra-high frequency signal and the ultrasonic signal. Specifically, the detection optical fiber in the optical fiber ultrasonic sensor unit 5 can be a single-mode optical fiber, and the length can be 50m. Figure 3 As shown, the fiber optic ultrasonic sensor unit 5 can be in a ring structure and can be made into a sensor probe by vacuum casting. The diameter of the fiber optic ring is 30 mm, and 32 layers are wound on the core shaft. While avoiding excessive bending that causes a significant attenuation of the signal, the modulation amplitude of the phase of the interference light can be increased, so that the system has a higher detection sensitivity, and its operating frequency band covers 80kHz~200kHz. The detection optical fiber in the fiber optic ultrasonic sensor unit 5 is subjected to the pressure of the ultrasonic wave generated by the local discharge, causing a slight change in the length of this part of the optical fiber, which ultimately causes the interference phase of the reference light and the detection light to change, thereby detecting the local discharge and obtaining the ultrasonic signal generated by the local discharge. The bottom of the fiber optic ultrasonic sensor unit 5 (such as Figure 2The left side of the optical fiber ultrasonic sensor unit 5 is connected with an angle adjustment unit 4, which can adjust the angle of the optical fiber ultrasonic sensor unit 5, increase the sensor detection range, or adjust the detection angle to select the optimal angle for detection, enhance the sensitivity of the detection system, and ensure the accuracy of the detection. Among them, the optical fiber ultrasonic sensor unit 5 can have five gears, namely the first gear, the second gear, the third gear, the fourth gear and the fifth gear, and the corresponding angles, that is, the angles between the optical fiber ultrasonic sensor unit 5 and the vertical housing of the transformer 8 to be tested are 30°, 60°, 90°, 120° and 150° respectively. In order to facilitate the replacement of the optical fiber ultrasonic sensor unit 5, preferably, the optical fiber ultrasonic sensor unit 5 and the angle adjustment unit 4 are connected in a detachable manner, for example, the optical fiber ultrasonic sensor unit 5 and the angle adjustment unit 4 can be connected by threaded connection, of course, they can also be connected by other methods, and there is no limitation on it in this embodiment.

[0023] The piezoelectric self-energy unit 6 can be arranged on the mounting unit 1, and the piezoelectric self-energy unit 6 is connected to the angle adjustment unit 4, and is used to generate an electrical signal when the mounting unit 1 vibrates with the transformer 8 to be tested and the vibration signal acts on the piezoelectric self-energy unit 6, so as to power the angle adjustment unit 4. Specifically, the piezoelectric self-energy unit 6 can be a piezoelectric ceramic sheet, and the mounting unit 1 vibrates synchronously with the transformer 8 to be tested, so that when the transformer 8 to be tested vibrates, the vibration signal acts on the piezoelectric self-energy unit 6, so that the piezoelectric self-energy unit 6 generates an electrical signal, and then powers the control unit and other components. In this embodiment, the piezoelectric self-energy unit 6 can be a cylindrical piezoelectric ceramic sheet with a bottom radius of 2 cm and a thickness of 1 cm. The resonant frequency of the piezoelectric ceramic sheet of this size is more consistent with the frequency of transformer vibration. When the vibration signal of the transformer acts on the piezoelectric sheet, more electrical energy can be generated. The piezoelectric sheet is connected to the angle adjustment unit 4 through a wire, and can also be connected to the control unit to provide electrical energy for the angle control and the control unit.

[0024] In this embodiment, the angle adjustment unit 4 is connected to a control unit (not shown in the figure), which is used to receive the UHF signal and the ultrasonic signal, and control the angle adjustment unit 4 based on the UHF signal and the ultrasonic signal, so as to control the angle adjustment unit 4 to drive the fiber optic ultrasonic sensor unit to rotate to the optimal angle. Specifically, the control unit is respectively connected to the angle adjustment unit 4, the UHF sensor unit 2, and the fiber optic ultrasonic sensor unit 5, and is used to receive the UHF signal obtained by the UHF sensor unit 2 and the ultrasonic signal obtained by the fiber optic ultrasonic sensor unit 5, so as to control the angle adjustment unit 4 based on the amplitude of the UHF signal and the amplitude of the ultrasonic signal, so as to adjust the arrangement angle of the fiber optic ultrasonic sensor unit 5, especially the angle between the fiber optic ultrasonic sensor unit 5 and the vertical housing of the transformer 8 to be tested.

[0025] In this embodiment, the UHF sensing unit 2 and the fiber optic ultrasonic sensing unit 5 are also connected to a wireless signal transmission unit for transmitting the UHF signal acquired by the UHF sensing unit 2 and the ultrasonic signal acquired by the fiber optic ultrasonic sensing unit 5 to a remote monitoring room.

[0026] Continue to see Figure 1 The mounting unit 1 includes: an insulating disk 11, a mounting disk 12 and a flange 13; wherein one side of the mounting disk 12 (such as Figure 1 The flange 13 is connected to the other side of the mounting plate 11 (as shown in the right side) and is sealed to the insulating plate 11; Figure 1 The left side shown in the figure is sealed and connected, and the insulating disk 11 is away from the side of the mounting disk 12 (such as Figure 1 The right side shown in FIG. 1 is opposite to the side of the UHF sensor unit 2 facing away from the connecting rod 3 (as shown in FIG. Figure 1 left side shown) sealed connection.

[0027] Specifically, one side of the insulating disk 11 is sealed and connected to the side of the UHF sensing unit 2 away from the connecting rod 3, the other side of the insulating disk 11 is connected to one side of the mounting disk 12, the side of the mounting disk 12 away from the insulating disk 11 is sealed and connected to the flange 13, and the side of the flange 13 away from the mounting disk 12 can be connected to a wireless signal transmission unit.

[0028] In this embodiment, the connecting rod 3 can be a telescopic rod structure, which is used to adjust the position of the fiber optic ultrasonic sensor unit 5 placed inside the transformer 8 to be tested, which can expand the detection range of the sensor, and can also refer to the angle adjustment to select the optimal length for detection. Specifically, the connecting rod 3 is hollow inside and is used for threading to realize the extraction of the optical fiber in the fiber optic ultrasonic sensor unit 5. Among them, the connecting rod 3 can be a hollow telescopic rod with a bottom radius of 2 cm made of XLPE. In order to ensure the insulation performance of the transformer, the bottom radius of the cavity inside the telescopic rod is 0.5 cm, and the fiber optic ultrasonic sensor unit 5 extends from the ultra-high frequency sensor unit 2 into the inside of the transformer 8 to be tested. The length range of the telescopic rod structure deep into the transformer 8 to be tested is 5cm-20cm. On the basis of ensuring that the insulation performance of the transformer is not damaged, the monitoring range is expanded as much as possible, and the detection sensitivity and coverage breadth of partial discharge events are improved. Among them, the optical fiber of the fiber optic ultrasonic sensor unit 5 is extracted through the telescopic rod structure and can be connected to an external demodulator. The sensor as a whole reaches the IP68 protection level.

[0029] Continue to see Figure 2 The outer wall of the connecting rod 3 is provided with a carbon fiber shell 31, and the connecting rod control line 32 and the optical fiber lead-out line 33 are provided inside. Among them, the two ends of the connecting rod control line 32 are connected to the control unit and the angle adjustment unit 4 respectively.

[0030] In this embodiment, the control unit is also used to control the built-in acoustic-electric combined sensor of the transformer to perform preliminary detection on the transformer 8 to be tested at regular intervals, obtain the amplitude of the ultra-high frequency signal and the amplitude of the ultrasonic signal generated by the partial discharge in the transformer 8 to be tested, and compare them with the first threshold and the second threshold respectively; when the amplitude of the ultra-high frequency signal is greater than the first threshold and / or the amplitude of the ultrasonic signal is greater than the second threshold, the control unit controls the angle adjustment unit 4 to drive the optical fiber ultrasonic sensor unit 5 to rotate, so that the optical fiber ultrasonic sensor unit 5 rotates to each gear position in turn, and obtains the amplitude of the ultrasonic signal generated by the partial discharge in the transformer 8 to be tested at each gear position; when the amplitude of the ultrasonic signal in at least one gear position is greater than the second threshold, compare the amplitude of the ultrasonic signal in each gear position, and determine the gear position with the largest amplitude of the ultrasonic signal as the optimal gear position; the control unit controls the angle adjustment unit 4 to drive the optical fiber ultrasonic sensor unit 5 to rotate to the optimal gear position, and performs regular and intermittent partial discharge detection of the transformer to be tested at the optimal gear position, and obtains the ultra-high frequency signal and the ultrasonic signal generated by the partial discharge in the transformer 5 to be tested, so as to monitor the operating state of the transformer 5 to be tested. In this embodiment, when the amplitude of the ultrasonic signal at each gear is less than or less than the second threshold, the control unit controls the angle adjustment unit 4 to drive the optical fiber ultrasonic sensor unit to rotate to the initial gear, and continues to perform periodic preliminary detection on the transformer 8 to be tested until the amplitude of the ultrasonic signal at at least one gear is greater than the second threshold. Among them, the detection frequency of the periodic partial discharge detection is greater than the detection frequency of the periodic preliminary detection, which can be determined according to actual conditions and is not limited in this embodiment.

[0031] In summary, the transformer built-in acoustic-electric combined sensor provided in this embodiment combines the partial discharge measurement advantages of the UHF sensing unit 2 and the fiber optic ultrasonic sensing unit 5, and realizes the simultaneous acquisition of UHF signals and fiber optic ultrasonic signals through the joint detection of acoustic and electrical signals, thereby solving the problem of limited sensitivity of single partial discharge detection. The embedded structure is adopted, and the fiber optic ultrasonic sensing probe is located inside the transformer, which can improve the anti-interference ability, detection sensitivity and accuracy of defect location. The UHF sensing unit 2 and the fiber optic ultrasonic sensing unit 5 can effectively detect the partial discharge generated inside the transformer and quickly capture the partial discharge signal. Compared with the simultaneous use of the fiber optic ultrasonic sensor and the UHF sensor for detection at different positions, it supports the synchronous detection of the fiber optic ultrasonic signal and the UHF signal, has good consistency, and can efficiently monitor Measure the internal discharge of the transformer, discover latent defects, diagnose the degree of insulation damage caused by defects under the action of the electric field, and then effectively carry out fault warning and improve the status maintenance level of the transformer; the optical fiber ring of the optical fiber ultrasonic sensor is made into a sensor probe by vacuum casting, and at the same time, various parts of the combined sensor such as the mounting plate, the insulating plate, the ultra-high frequency sensing unit 2 and the optical fiber ultrasonic sensing unit 5 are sealed by a sealing ring, and the combined sensor becomes one with the transformer after installation, has good sealing, and can ensure reliable operation under high pressure and high oil temperature environment; adjust the angle of the optical fiber ultrasonic sensing unit 5 by the angle adjustment unit 4, increase the sensor detection range, or adjust the detection angle to select the optimal angle for detection, enhance the sensitivity of the detection system, and ensure the accuracy of detection.

[0032] Method Example: See also Figure 4 , which is a flowchart of a partial discharge detection method provided by an embodiment of the present invention. As shown in the figure, the partial discharge detection method, i.e., the transformer partial discharge signal detection method, comprises the following steps: Step S1, using the above transformer built-in acoustic-electric combined sensor to perform preliminary detection on the transformer to be tested, obtain the amplitude of the ultra-high frequency signal and the amplitude of the ultrasonic signal generated by partial discharge in the transformer to be tested, and compare them with the first threshold and the second threshold respectively.

[0033] Specifically, the optical fiber ultrasonic sensor unit in the above transformer built-in acoustic-electric combined sensor is in the initial gear position, wherein the initial gear position may be a default gear position, for example, the second gear position or the third gear position, which may be determined according to actual conditions, and is not limited in this embodiment. First, a preliminary detection is performed at regular intervals by the ultra-high frequency sensor unit 2 and the optical fiber ultrasonic sensor unit 5 in the transformer built-in acoustic-electric combined sensor, that is, the transformer to be tested is started to be detected every first preset time period, and the detection time may be 20ms, or other time periods, and is not limited in this embodiment; that is, a 20ms detection is performed first to obtain the amplitude of the ultra-high frequency signal and the amplitude of the ultrasonic signal, and the amplitude of the ultra-high frequency signal is compared with the first threshold, and the amplitude of the ultrasonic signal is compared with the second threshold.

[0034] Step S2, when the amplitude of the UHF signal is greater than the first threshold value and / or the amplitude of the ultrasonic signal is greater than the second threshold value, the optical fiber ultrasonic sensing unit is driven to rotate by the angle adjustment unit, so that the optical fiber ultrasonic sensing unit is rotated to each gear position in turn, and at each gear position, the amplitude of the ultrasonic signal generated by the partial discharge in the transformer to be tested is obtained; wherein the optical fiber ultrasonic sensing unit has multiple gear positions to correspond to different arrangement angles.

[0035] Specifically, when the amplitude of the UHF signal is less than or equal to the first threshold and the amplitude of the ultrasonic signal is less than or equal to the second threshold, step S1 is repeated, that is, the gear position is maintained, and the transformer to be tested is preliminarily tested periodically by the UHF sensing unit 2 and the optical fiber ultrasonic sensing unit 5 until the amplitude of the UHF signal is greater than the first threshold and / or the amplitude of the ultrasonic signal is greater than the second threshold. When the amplitude of the UHF signal is greater than the first threshold and / or the amplitude of the ultrasonic signal is greater than the second threshold, that is, when the amplitude of the UHF signal is greater than the first threshold, the amplitude of the ultrasonic signal is greater than the second threshold, or the amplitude of the UHF signal is greater than the first threshold and the amplitude of the ultrasonic signal is greater than the second threshold, the control angle adjustment unit 4 is started to drive the optical fiber ultrasonic sensing unit 5 to rotate, so that the optical fiber ultrasonic sensing unit 5 rotates to each gear position in turn, and at each gear position, the amplitude of the ultrasonic signal generated by the partial discharge in the transformer to be tested is obtained.

[0036] Step S3, when the amplitude of the ultrasonic signal in at least one gear is greater than the second threshold, compare the amplitudes of the ultrasonic signals in each gear and determine the gear with the largest amplitude of the ultrasonic signal as the optimal gear.

[0037] Specifically, when the amplitude of the ultrasonic signal at each gear is less than or less than the second threshold, the control angle adjustment unit 4 is started to drive the optical fiber ultrasonic sensor unit 5 to rotate to the initial gear, i.e., the default gear, and repeat steps S1 and S2 to perform signal detection until the amplitude of the ultrasonic signal at at least one gear is greater than the second threshold. When the amplitude of the ultrasonic signal at at least one gear is greater than the second threshold, the amplitudes of the ultrasonic signals at each gear are compared, and the gear with the largest amplitude of the ultrasonic signal is determined as the optimal gear.

[0038] Step S4, driving the optical fiber ultrasonic sensing unit to rotate to the optimal gear position through the angle adjustment unit, and performing periodic partial discharge detection of the transformer under test at the optimal gear position, obtaining the ultra-high frequency signal and ultrasonic signal generated by the partial discharge in the transformer under test, so as to monitor the operating status of the transformer under test.

[0039] Specifically, the control angle adjustment unit 4 is started to drive the optical fiber ultrasonic sensing unit 5 to rotate to the optimal gear position determined in step S3, and the periodic intermittent partial discharge detection of the transformer to be tested is performed at the optimal gear position, that is, the transformer to be tested is started to be tested every second preset time period, and the detection time can be 20ms, or other time periods, which are not limited in this embodiment, and the ultra-high frequency signal and ultrasonic signal generated by the partial discharge in the transformer to be tested are obtained to monitor the operating status of the transformer to be tested. Among them, the detection frequency of the periodic intermittent partial discharge detection is greater than the detection frequency of the periodic preliminary detection in step S1, that is, the second preset time period is less than the first preset time period.

[0040] In summary, the partial discharge detection method provided in this embodiment combines the partial discharge measurement advantages of the UHF sensing unit 2 and the fiber optic ultrasonic sensing unit 5, and realizes the simultaneous acquisition of the UHF signal and the fiber optic ultrasonic signal through the joint detection of acoustic and electrical signals, thereby solving the problem of limited sensitivity of single partial discharge detection. The embedded structure is adopted, and the fiber optic ultrasonic sensing probe is located inside the transformer, which can improve the anti-interference ability, detection sensitivity and accuracy of defect location. The UHF sensing unit 2 and the fiber optic ultrasonic sensing unit 5 can effectively detect the partial discharge generated inside the transformer and quickly capture the partial discharge signal. Compared with the simultaneous use of the fiber optic ultrasonic sensor and the UHF sensor for detection at different positions, it supports the synchronous detection of the fiber optic ultrasonic signal and the UHF signal, has good consistency, and can efficiently monitor the transformer. The internal discharge of the transformer can be detected to find latent defects, and the degree of insulation damage caused by the defects under the action of the electric field can be diagnosed, so as to effectively carry out fault warning and improve the condition maintenance level of the transformer; the optical fiber ring of the optical fiber ultrasonic sensor is made into a sensor probe by vacuum casting, and at the same time, various parts of the combined sensor such as the mounting plate, the insulating plate, the ultra-high frequency sensing unit 2 and the optical fiber ultrasonic sensing unit 5 are sealed by sealing rings, and the combined sensor becomes one with the transformer after installation, has good sealing, and can ensure reliable operation under high pressure and high oil temperature environment; the angle of the optical fiber ultrasonic sensing unit 5 is adjusted by the angle adjustment unit 4 to increase the sensor detection range, or adjust the detection angle to select the optimal angle for detection, enhance the sensitivity of the detection system, and ensure the accuracy of detection.

[0041] It should be noted that, in the description of the present invention, terms such as "up", "down", "left", "right", "inside" and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings. This is merely for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.

[0042] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0043] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A transformer built-in acoustic and electrical combined sensor, characterized in that: include: An installation unit, used for being installed on the transformer to be tested; A UHF sensing unit, arranged on the mounting unit, for detecting UHF signals generated by partial discharge in the transformer to be tested; A connecting rod, one end of which is connected to the UHF sensing unit and the other end of which is provided with an angle adjustment unit; The optical fiber ultrasonic sensing unit is arranged in the angle adjustment unit, and the angle adjustment unit is used to adjust the arrangement angle of the optical fiber ultrasonic sensing unit to obtain the optimal detection angle, so that the optical fiber ultrasonic sensing unit can detect the ultrasonic signal generated by the partial discharge in the transformer to be tested at the optimal detection angle, thereby monitoring the operating status of the transformer to be tested based on the ultra-high frequency signal and the ultrasonic signal.

2. The transformer built-in acoustic-electric combined sensor according to claim 1, characterized in that: A piezoelectric self-energy extraction unit is provided on the mounting unit, and the piezoelectric self-energy extraction unit is connected to the angle adjustment unit. When the mounting unit vibrates along with the transformer to be tested and the vibration signal acts on the piezoelectric self-energy extraction unit, an electrical signal is generated to power the angle adjustment unit.

3. The transformer built-in acoustic-electric combined sensor according to claim 2, characterized in that: The piezoelectric self-energy extraction unit is a cylindrical piezoelectric ceramic piece.

4. The transformer built-in acoustic-electric combined sensor according to any one of claims 1 to 3, characterized in that: The installation unit comprises: Insulation disc; A mounting plate, one side of which is sealingly connected to the insulating plate; The flange is sealed and connected to the other side of the mounting plate, and the side of the insulating plate facing away from the mounting plate is sealed and connected to the side of the UHF sensor unit facing away from the connecting rod.

5. The transformer built-in acoustic-electric combined sensor according to any one of claims 1 to 3, characterized in that: The connecting rod is a telescopic rod structure, which is used to adjust the position of the optical fiber ultrasonic sensor unit inside the transformer to be tested.

6. The transformer built-in acoustic-electric combined sensor according to any one of claims 1 to 3, characterized in that: The connecting rod is hollow inside and is used for threading to realize the lead-out of the optical fiber in the optical fiber ultrasonic sensor unit.

7. The transformer built-in acoustic-electric combined sensor according to any one of claims 1 to 3, characterized in that: The optical fiber ultrasonic sensor unit is a sensor probe with a ring structure made by vacuum casting, and is connected to the angle adjustment unit in a detachable manner.

8. The transformer built-in acoustic-electric combined sensor according to any one of claims 1 to 3, characterized in that: The angle adjustment unit is connected to a control unit for receiving ultra-high frequency signals and ultrasonic signals, and controlling the angle adjustment unit based on the ultra-high frequency signals and ultrasonic signals, so as to control the angle adjustment unit to drive the optical fiber ultrasonic sensing unit to rotate to an optimal angle.

9. A partial discharge detection method, characterized in that: The steps include: Step S1, using the transformer built-in acoustic-electric combined sensor as described in any one of claims 1 to 8, to perform preliminary detection on the transformer to be tested, obtain the amplitude of the ultra-high frequency signal and the amplitude of the ultrasonic signal generated by the partial discharge in the transformer to be tested, and compare them with the first threshold and the second threshold respectively; Step S2, when the amplitude of the UHF signal is greater than the first threshold value and / or the amplitude of the ultrasonic signal is greater than the second threshold value, the optical fiber ultrasonic sensor unit is driven to rotate by the angle adjustment unit, so that the optical fiber ultrasonic sensor unit is rotated to each gear position in turn, and at each gear position, the amplitude of the ultrasonic signal generated by the partial discharge in the transformer to be tested is obtained; wherein the optical fiber ultrasonic sensor unit has a plurality of gear positions to correspond to different arrangement angles; Step S3, when the amplitude of the ultrasonic signal in at least one gear is greater than the second threshold, compare the amplitudes of the ultrasonic signals in each gear, and determine the gear with the largest amplitude of the ultrasonic signal as the optimal gear; Step S4, driving the optical fiber ultrasonic sensing unit to rotate to an optimal gear position through the angle adjustment unit, and performing periodic partial discharge detection of the transformer to be tested at the optimal gear position, obtaining ultra-high frequency signals and ultrasonic signals generated by partial discharge in the transformer to be tested, so as to monitor the operating status of the transformer to be tested.

10. The partial discharge detection method according to claim 9, characterized in that: When the amplitude of the ultrasonic signal at each gear position is less than or less than the second threshold, the optical fiber ultrasonic sensor unit is driven to rotate to the initial gear position through the angle adjustment unit, and steps S1 and S2 are repeated.

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