Partial discharge detection device and method based on distributed capacitive micro-machined ultrasonic transducer

Abstract

The invention belongs to the technical field of acoustic emission sensors, and discloses a partial discharge detection device and method based on distributed capacitive micro-machined ultrasonic transducers, and the device comprises the steps: arranging at least four capacitive micro-machined ultrasonic transducers at different positions of a housing of a to-be-detected transformer; acquiring an ultrasonic signal in the transformer in real time through the capacitive micro-mechanical ultrasonic transducer; and calculating the position information of the partial discharge source in the transformer by using the time information of the ultrasonic signals acquired by all the capacitive micro-mechanical ultrasonic transducers, the propagation speed of the ultrasonic waves in the transformer and the position information of each capacitive micro-mechanical ultrasonic transducer. According to the invention, the MEMS ultrasonic sensor is adopted to measure the partial discharge phenomenon of the transformer, the measurement result is accurate, and the partial discharge source with partial discharge in the transformer can be accurately judged.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of acoustic emission sensors, and particularly relates to a partial discharge detection device and method based on a distributed capacitive micromechanical ultrasonic transducer. BACKGROUND

[0002] In the power system, partial discharge refers to a partial discharge phenomenon occurring inside or on the surface of an insulating material under the action of a high-voltage electric field. Its harmfulness is manifested in local heating, charged particle impact, chemical active substance generation, and radiation, which can accelerate insulation deterioration and possibly cause equipment failure, seriously threatening the safe and stable operation of the power system. Therefore, it is crucial to detect partial discharge of electrical equipment to identify insulation defects. Among them, ultrasonic technology has important application value in transformer partial discharge detection: when partial discharge occurs inside the transformer, ultrasonic signals of a specific frequency are generated, which can be received by the ultrasonic sensor installed on the shell; this technology, with the advantages of strong anti-electromagnetic interference ability, high discharge source positioning accuracy, and multi-dimensional characteristic analysis of signal amplitude, frequency, and phase, can not only effectively determine whether the transformer has partial discharge phenomenon, but also realize the positioning diagnosis of the discharge source, thereby providing key technical support for timely detection of insulation defects and reliable operation of the transformer and power system.

[0003] The size and weight of traditional acoustic sensors are relatively large, which may be limited by space when installed on the transformer, and may have some impact on the structure and operation of the transformer. Secondly, the manufacturing cost of traditional ultrasonic sensors is relatively high, which limits large-scale application. Thirdly, it is usually difficult to integrate with other detection equipment or systems, which is not conducive to intelligent and automated detection and monitoring. In addition, the sensitivity and resolution of traditional ultrasonic sensors are relatively low, which may not accurately detect weak partial discharge ultrasonic signals, and the analysis of partial discharge characteristics is not comprehensive and accurate. Moreover, its anti-electromagnetic interference and anti-mechanical vibration capabilities are limited, and in the complex operating environment of the transformer, the stability and reliability of the detection results may be affected. SUMMARY

[0004] To solve the problems in the prior art, the purpose of the present application is to provide a partial discharge detection device and method based on a distributed capacitive micromechanical ultrasonic transducer. The present application uses a MEMS ultrasonic sensor to measure the partial discharge phenomenon of the transformer, and the measurement result is accurate and can accurately determine the partial discharge source inside the transformer.

[0005] To achieve the above purpose, the present application adopts the following technical solution: A partial discharge detection method based on a distributed capacitive micromechanical ultrasonic transducer, comprising the following processes: Arranging at least four capacitive micromachined ultrasonic transducers at different positions of the shell of the transformer to be detected, and acquiring ultrasonic signals in the transformer in real time through the capacitive micromachined ultrasonic transducers; Using the time information of the ultrasonic signals collected by all the capacitive micromachined ultrasonic transducers, the propagation speed of the ultrasonic waves in the transformer, and the position information of each capacitive micromachined ultrasonic transducer, the position information of the partial discharge source in the transformer is calculated.

[0006] Preferably, the above-mentioned partial discharge detection method of the present application further comprises the following process: Among the acquired ultrasonic signals in the transformer, the ultrasonic signal with the largest amplitude is screened out; the capacitive micromachined ultrasonic transducer that collects the ultrasonic signal with the largest amplitude is determined, and the remaining capacitive micromachined ultrasonic transducers are arranged at different positions near the capacitive micromachined ultrasonic transducer that collects the ultrasonic signal with the largest amplitude; The above-mentioned process is repeated at least once, and then the position information of the partial discharge source in the transformer is calculated using the time information of the ultrasonic signals collected by all the capacitive micromachined ultrasonic transducers, the propagation speed of the ultrasonic waves in the transformer, and the position information of each capacitive micromachined ultrasonic transducer.

[0007] Preferably, the number of capacitive micromachined ultrasonic transducers is four, and the four capacitive micromachined ultrasonic transducers are respectively denoted as the first capacitive micromachined ultrasonic transducer, the second capacitive micromachined ultrasonic transducer, the third capacitive micromachined ultrasonic transducer, and the fourth capacitive micromachined ultrasonic transducer. The spatial coordinates of the first capacitive micromachined ultrasonic transducer, the second capacitive micromachined ultrasonic transducer, the third capacitive micromachined ultrasonic transducer, and the fourth capacitive micromachined ultrasonic transducer are respectively denoted as 、 、 and The time when the first capacitive micromachined ultrasonic transducer, the second capacitive micromachined ultrasonic transducer, the third capacitive micromachined ultrasonic transducer, and the fourth capacitive micromachined ultrasonic transducer receive the ultrasonic signals in the transformer is respectively denoted as 、 、 and The propagation speed of the ultrasonic waves in the transformer is The spatial coordinates of the partial discharge source in the transformer are calculated through the following equation set: .

[0008] The present invention also provides a partial discharge detection device based on a distributed capacitive micromachined ultrasonic transducer, which is used to implement the partial discharge detection method based on a distributed capacitive micromachined ultrasonic transducer as described above. The device includes at least four capacitive micromachined ultrasonic transducers, all of which are connected to a signal processing module. The signal processing module is used to calculate the position information of the partial discharge source in the transformer using the time information of the ultrasonic signals collected by all capacitive micromachined ultrasonic transducers, the propagation speed of the ultrasonic wave in the transformer, and the position information of each capacitive micromachined ultrasonic transducer.

[0009] Preferably, all capacitive micromachined ultrasonic transducers are wirelessly connected to the signal processing module via a Bluetooth module.

[0010] Preferably, for each capacitive micromachined ultrasonic transducer, the capacitive micromachined ultrasonic transducer is arranged in a sensor housing, a matching layer is provided at the bottom of the sensor housing, the capacitive micromachined ultrasonic transducer is located in the sensor housing and fixed on the matching layer, the matching layer is connected to the outer casing of the transformer, a high-frequency connector is provided on the sensor housing, and the capacitive micromachined ultrasonic transducer is connected to the high-frequency connector.

[0011] Preferably, the sensor housing comprises an outer conical metal housing, and the inner surface of the conical metal housing is provided with a sound-absorbing cotton layer.

[0012] Preferably, the capacitive micromachined ultrasonic transducer and the matching layer are connected via an adhesive layer, and a fixing bracket for fixing the capacitive micromachined ultrasonic transducer is provided on the adhesive layer.

[0013] Preferably, the capacitive micromachined ultrasonic transducer includes a packaging shell, the bottom of which is fixed to a PCB printed circuit board through an adhesive layer, a capacitive micromachined ultrasonic transducer chip and an ASIC chip are provided inside the packaging shell, the capacitive micromachined ultrasonic transducer chip and the ASIC chip are electrically connected and both are fixed on the adhesive layer, the ASIC chip is electrically connected to the PCB printed circuit board, the PCB printed circuit board is electrically connected to the high-frequency connector, the outside of the ASIC chip is also poured with potting glue, and a sound hole for transmitting sound waves is provided at the top of the packaging shell at a position opposite to the capacitive micromachined ultrasonic transducer chip.

[0014] Preferably, the capacitive micromachined ultrasonic transducer chip adopts a MEMS ultrasonic sensor.

[0015] The present invention has the following beneficial effects: The application utilizes the capacitive micromachined ultrasonic transducer to detect the partial discharge phenomenon of the transformer, according to the rapid energy release and the transient elastic wave generated by the partial discharge, the propagation reaches the surface of the sensor, when the ultrasonic transducer surface receives the mechanical vibration transmitted by the ultrasonic wave, the vibrating diaphragm of the capacitive micromachined ultrasonic transducer generates displacement under the vibration, changes the distance between the two polar plates, and causes the capacitance value to change. The capacitive micromachined ultrasonic transducer further converts the capacitance change into an electrical signal output, obtains an electrical signal easy to observe, record and process, realizes the monitoring of the partial discharge. The capacitive micromachined ultrasonic transducer used in the application has the characteristics of small size and light weight, so it is convenient to install in the narrow space of the transformer and has little influence on the capacitive micromachined ultrasonic transducer, the cost is low, can realize large-scale application, is easy to integrate, can improve the system performance and reliability, has superior performance, can accurately detect weak signals and analyze discharge characteristics, has strong anti-interference ability and can work stably in complex environment, can effectively improve the accuracy and efficiency of the partial discharge detection, and ensures the safe and stable operation of the transformer. Further, the capacitive micromachined ultrasonic transducer is used to replace the traditional ultrasonic probe to arrange in a distributed manner on the surface of the transformer, the amplitude of the collected ultrasonic signal is compared, the detection range is reduced, then the distributed arrangement mode is changed, reacquisition is performed, and the position of the partial discharge source is calculated through the acoustic-acoustic positioning method, so that the accuracy of the partial discharge source position judgment is high. BRIEF DESCRIPTION OF DRAWINGS

[0016] The accompanying drawings are included to provide a further understanding of the application, and constitute a part of the specification, and together with the embodiments of the application, make a further detailed explanation, but do not constitute a limitation to the application.

[0017] Figure 1 It is a complete packaging structure schematic diagram of the capacitive micromachined ultrasonic transducer in the embodiment of the application.

[0018] Figure 2 It is a structure schematic diagram of the capacitive micromachined ultrasonic transducer in the embodiment of the application.

[0019] Figure 3 It is a structure schematic diagram of the capacitive micromachined ultrasonic transducer chip in the embodiment of the application.

[0020] Figure 4 It is a distributed arrangement method schematic diagram for preliminarily determining the region where the partial discharge source is located in the embodiment of the application.

[0021] Figure 5 It is a distributed arrangement method for further determining the position where the partial discharge source is located in the embodiment of the application.

[0022] Figure 6FIG. 1 is a schematic diagram of a partial discharge detection device based on distributed capacitive micromachined ultrasonic transducers in an embodiment of the present application.

[0023] In the figure: 1, MEMS acoustic emission sensor; 2, sensor shell; 3, conical metal shell; 4, adhesive layer; 5, matching layer; 6, fixed support; 7, capacitive micromachined ultrasonic transducer; 7-1, first capacitive micromachined ultrasonic transducer; 7-2, second capacitive micromachined ultrasonic transducer; 7-3, third capacitive micromachined ultrasonic transducer; 7-4, fourth capacitive micromachined ultrasonic transducer; 8, high-frequency connector; 9, sound-absorbing cotton layer; 10, transformer; 11, partial discharge source.

[0024] 71, packaging shell; 72, gold wire; 73, capacitive micromachined ultrasonic transducer chip; 74, PCB printed circuit board; 75, acoustic hole; 76, potting glue; 77, ASIC chip; 78, sealing layer.

[0025] 731, metal upper electrode; 732, electrical isolation layer; 733, vibrating diaphragm; 734, isolation groove; 735, cavity; 736, support column; 737, silicon substrate; 738, metal lower electrode. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the embodiments of the present application and the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0027] Referring to Figure 6 The partial discharge detection method based on distributed capacitive micromachined ultrasonic transducers in the present application includes the following processes: At least four capacitive micromachined ultrasonic transducers are arranged at different positions of the shell of the transformer 10 to be detected, and ultrasonic signals in the transformer are acquired in real time by the capacitive micromachined ultrasonic transducers. The position information of the partial discharge source in the transformer is calculated by using the time information of the ultrasonic signals collected by all the capacitive micromachined ultrasonic transducers, the propagation speed of the ultrasonic waves in the transformer, and the position information of each capacitive micromachined ultrasonic transducer.

[0028] Referring to Figure 1In the above scheme of the present application, the capacitive micromachined ultrasonic transducer can adopt the following arrangement form, specifically, each capacitive micromachined ultrasonic transducer 7 can be arranged in the sensor shell 2, the sensor shell 2 is provided with a matching layer 5, the capacitive micromachined ultrasonic transducer is located in the sensor shell 2 and fixed on the matching layer 5, the matching layer 5 is connected with the shell of the transformer, the sensor shell 2 is provided with a high-frequency connector 8, and the capacitive micromachined ultrasonic transducer is connected with the high-frequency connector 8. Wherein, the matching layer 5 can be made of a material with acoustic characteristics adapted, and its acoustic impedance is between the sensor and the external medium. The capacitive micromachined ultrasonic transducer 7, the sensor shell 2, the matching layer 5 and the high-frequency connector 8 constitute a MEMS acoustic emission sensor 1. In the above scheme, the specific structure of the sensor shell 2 can adopt the following structure: the sensor shell 2 includes a conical metal shell 3 as the outermost layer, an acoustic cotton layer 9 as the inner layer, the acoustic cotton layer 9 is arranged on the inner wall surface of the conical metal shell 3, and the high-frequency connector 8 is mounted on the conical metal shell 3. The conical metal shell 3 is made of stainless steel material, which is used to protect the internal components from the influence of external factors such as dust, water vapor and electromagnetic interference. The conical (i.e. circular truncated cone) structure can focus sound waves, enhance propagation distance and directivity, reduce energy scattering and attenuation, and at the same time can reduce the reflection of the shell to the sound wave, reduce the interference signal, improve the resolution and accuracy. In addition, the conical structure has good mechanical stability and can resist external force impact to protect the internal components. The acoustic cotton layer is located in the inner layer of the metal shell, which can filter out environmental noise and external interference and create a sealed environment for the internal sensitive components. The high-frequency connector 8 ensures the transmission of the electrical signal from the CMUT to the cable with low noise and low capacitance. The fixing bracket 6 is used to fix the position of the MEMS acoustic emission sensor 1. In the above scheme, the capacitive micromachined ultrasonic transducer and the matching layer 5 can be connected through the adhesive layer 4, and the fixing bracket 6 for fixing the capacitive micromachined ultrasonic transducer can also be arranged on the adhesive layer 4.

[0029] Referring to Figure 2The capacitive micromachined ultrasonic transducer can adopt the following structure: the capacitive micromachined ultrasonic transducer comprises a packaging shell 71, the bottom of the packaging shell 71 is fixed to a PCB printed circuit board 74 through an adhesive layer 78, the inside of the packaging shell 71 is provided with a capacitive micromachined ultrasonic transducer chip 73 and an ASIC chip 77, the capacitive micromachined ultrasonic transducer chip 73 and the ASIC chip 77 are electrically connected and are both fixed on the adhesive layer 78, the ASIC chip 77 is electrically connected with the PCB printed circuit board 74, the PCB printed circuit board 74 is electrically connected with the high-frequency connector 8, the outside of the ASIC chip 77 is further poured with potting glue 76, and the top of the packaging shell 71 is provided with an acoustic hole 75 for transmitting sound waves at a position opposite to the capacitive micromachined ultrasonic transducer chip 73. The ASIC chip 77 can be integrated with a Bluetooth wireless transmission function. The packaging shell 71 plays a role in protecting internal components and shielding external interference. The acoustic hole 75 is used for transmitting sound into the inside of the sensor and balancing internal air pressure. The gold wire 72 is used for realizing electrical connection between the capacitive micromachined ultrasonic transducer chip 73 and the ASIC chip and other components, and is widely applied due to good conductivity and stability. The potting glue 76 protects the ASIC chip from mechanical damage and chemical corrosion. The capacitive micromachined ultrasonic transducer chip 73 is a core component of the sensor and can convert acoustic signals into electric signals. The ASIC chip 77 with the Bluetooth wireless transmission function is a special integrated circuit, which amplifies, filters and analog-to-digital converts the weak electric signals output by the capacitive micromachined ultrasonic transducer chip 73, and simultaneously contains the Bluetooth wireless transmission function, so as to realize wireless transmission of collected data. The sealing layer 78 can prevent external water vapor, dust and other impurities from entering and protect internal sensitive components. The PCB printed circuit board 74 provides electrical connection and physical support for various components in the sensor.

[0030] Referring to Figure 3The capacitive micromachined ultrasonic transducer chip 73 adopts a typical MEMS ultrasonic sensor, also called a core CMUT chip, which comprises a metal upper electrode 731, an electrical isolation layer 732, a vibrating diaphragm 733, an isolation groove 734, a cavity 735, a support column 736, a silicon substrate 737, a metal lower electrode 738, and the cavity 735 is sealed by the structures arranged in sequence from top to bottom; the vibrating diaphragm 733 is provided with the isolation groove 734, which penetrates the electrical isolation layer 732 and the vibrating diaphragm 733 in the thickness direction. The silicon substrate 737 adopts low-resistance silicon, which is beneficial to the formation of alloy with the lower electrode and has good electrical conductivity. The upper electrode 731, the electrical isolation layer 732, the vibrating diaphragm 733, the cavity 735 and the lower electrode 738 have consistent shapes; the electrical isolation layer 732, the vibrating diaphragm 733 and the lower electrode 738 have consistent lateral dimensions, and the lateral dimensions are greater than the lateral dimension of the cavity 735. The isolation groove 734 is annular, is located at the same height as the vibrating diaphragm 733, the central axis of the isolation groove 734 coincides with the geometric center line of the vibrating diaphragm 733, and is used for increasing the independence of the micro element. The electrical isolation layer 732 is located between the upper electrode 731 and the vibrating diaphragm 733, and is made of silicon oxide, which is used for preventing the Schottky barrier caused by the contact between the metal upper electrode and the semiconductor vibrating diaphragm from adversely affecting the normal work of the device. The upper and lower electrodes are made of metal materials, and the upper electrode is designed in a patterned manner. When an ultrasonic wave is incident on the CMUT chip, the pressure of the sound wave makes the vibrating diaphragm 733 vibrate. The vibration changes the distance between the metal upper electrode 731 and the metal lower electrode 738, and further causes the change of the capacitance, so that the electrical signal is easy to observe, record and process.

[0031] As Figure 1-Figure 3 shown, the specific principle of the above scheme of the application is as follows: during partial discharge, the transformer 10 often has charge neutralization, and a relatively steep current pulse is generated accordingly. The effect of the current pulse will make the area where the partial discharge occurs expand instantaneously due to heating, and a phenomenon similar to local thermal explosion is generated. After the discharge ends, the originally heated and expanded area will return to the original volume. The volume change caused by the expansion and contraction due to partial discharge will cause the instantaneous change of the density of the medium, forming the so-called ultrasonic wave, which propagates in a spherical wave mode to the surrounding from the discharge point. Therefore, when the transformer 10 has partial discharge, ultrasonic waves are also generated.

[0032] The capacitive micromachined ultrasonic transducer, as a core element of the capacitive micromachined ultrasonic transducer for partial discharge detection, mainly comprises upper and lower electrodes and an elastic diaphragm in the middle. When no ultrasonic wave is received, there is a certain initial capacitance between the upper and lower electrodes. When the ultrasonic wave is incident on the capacitive micromachined ultrasonic transducer, the pressure of the sound wave causes the elastic diaphragm to vibrate. This vibration changes the distance between the upper and lower electrodes, thereby causing a change in capacitance. Specifically, the diaphragm bends to one side under the action of the sound wave pressure, reducing the electrode spacing and increasing the capacitance; in the negative pressure stage of the sound wave, the diaphragm bends to the other side, increasing the electrode spacing and reducing the capacitance. In this way, the capacitive micromachined ultrasonic transducer converts the mechanical vibration of the ultrasonic wave into a change in capacitance, obtaining an electrical signal that is easy to observe, record and process, and realizing monitoring of partial discharge.

[0033] The capacitive micromachined ultrasonic transducer chip, as a core sensing component of the MEMS sensor for detecting partial discharge, is a key force for promoting the development of power system state monitoring and high-voltage equipment fault diagnosis. It has the characteristics of microarray design, can be flexibly deployed in complex power equipment to realize omnidirectional capture of partial discharge signals; low power consumption operation characteristics make it can work stably in power equipment online monitoring scene for a long time; high sensitivity and excellent resolution can accurately perceive the weak ultrasonic signal generated by partial discharge, even the subtle discharge characteristic change can be clearly captured; its high compatibility with complementary metal oxide semiconductor (CMOS) process facilitates system integration, greatly reduces the volume and cost of detection equipment. This environment-adaptive and high-performance CMUT not only meets the needs of smart grid for multifunctional, highly integrated and miniaturized partial discharge detection equipment, but also effectively promotes the development of power equipment fault warning and diagnosis technology, providing a solid guarantee for the safe and stable operation of power system.

[0034] The capacitive micromachined ultrasonic transducer is applied in the field of external acoustic emission partial discharge monitoring technology, and has the characteristics of miniaturization, high sensitivity and low power consumption.

[0035] In the above scheme of the present application, the MEMS acoustic emission sensor 1 is used to electromechanically convert the ultrasonic wave in the form of spherical wave propagating from the discharge point to the surrounding caused by the change of the medium density change caused by the expansion and contraction of the discharge area during partial discharge, to obtain the electrical signal easy to observe, record and process, and transmit the electrical signal to the high-frequency connector on the sensor shell 2 through the connecting line. The sensor shell 2 is used to protect the internal elements, create a sealed environment for the internal sensitive elements, and protect them from external environmental factors such as dust, water vapor, chemicals, mechanical impact and vibration. At the same time, the fixation and support of the sensor elements are also realized. And the electrical signal from the MEMS acoustic emission sensor 1 is transmitted through the high-frequency connector 8 and the low-noise, low-capacitance cable.

[0036] The distributed arrangement mode for realizing partial discharge detection is shown in the following figure: Figure 4-Figure 5 As shown in the figure, the capacitive micromechanical ultrasonic transducer for partial discharge detection is first installed outside the transformer in a distributed arrangement mode, and the amplitude of the collected ultrasonic signal is compared to make a preliminary judgment. The ultrasonic transducer close to the partial discharge source position collects ultrasonic signal with larger amplitude. Then the distributed arrangement mode is changed to narrow the detection range, and the position of the partial discharge source is calculated by the acoustic-acoustic positioning method through re-collection. The specific operation of the above process is as follows: in the obtained ultrasonic signal in the transformer, the ultrasonic signal with the largest amplitude of the ultrasonic signal is selected; the capacitive micromechanical ultrasonic transducer collecting the ultrasonic signal with the largest amplitude is determined, and the remaining capacitive micromechanical ultrasonic transducers are arranged at different positions close to the capacitive micromechanical ultrasonic transducer collecting the ultrasonic signal with the largest amplitude; The above process is repeated at least once, and then the time information of the ultrasonic signal collected by all capacitive micromechanical ultrasonic transducers, the propagation speed of the ultrasonic wave in the transformer and the position information of each capacitive micromechanical ultrasonic transducer are used to calculate the position information of the partial discharge source in the transformer.

[0037] The acoustic-acoustic positioning method used in the above scheme of the present application is to measure the time difference of the acoustic wave generated by the transformer partial discharge source reaching different sensors, establish a nonlinear equation set, and then solve it by using an optimization algorithm to determine the position of the partial discharge source.

[0038] Taking the number of four capacitive micromechanical ultrasonic transducers as an example for description: The four capacitive micromechanical ultrasonic transducers are respectively denoted as the first capacitive micromechanical ultrasonic transducer, the second capacitive micromechanical ultrasonic transducer, the third capacitive micromechanical ultrasonic transducer and the fourth capacitive micromechanical ultrasonic transducer, and the spatial coordinates of the four ultrasonic sensors are respectively ( ), i.e. the spatial coordinates of the first, second, third and fourth capacitive micromachined ultrasonic transducers are respectively denoted as , , and ; the spatial coordinate of the partial discharge source 11 is denoted as ; the time when the ultrasonic wave generator sends out the signal is measured by the four ultrasonic sensors , i.e. the time when the ultrasonic signal in the transformer is received by the first, second, third and fourth capacitive micromachined ultrasonic transducers is respectively denoted as , , and ; the speed of the ultrasonic wave propagation in the transformer is denoted as , and the spatial coordinate of the partial discharge source in the transformer is denoted as , which is calculated by the following formulae: (1) (2) (3) The formulae (1), (2) and (3) together constitute the ultrasonic hyperbolic positioning nonlinear equation group, and the solution of the equation group is , which is the coordinate of the partial discharge source.

[0039] Referring to Figure 6 , the application further provides a partial discharge detection device based on the distributed capacitive micromachined ultrasonic transducers, which is used for realizing the partial discharge detection method based on the distributed capacitive micromachined ultrasonic transducers as described above. The device comprises at least four capacitive micromachined ultrasonic transducers, all of which are connected with a signal processing module. The signal processing module is used for calculating the position information of the partial discharge source in the transformer by using the time information of the ultrasonic signals collected by all of the capacitive micromachined ultrasonic transducers, the speed of the ultrasonic wave propagation in the transformer and the position information of each capacitive micromachined ultrasonic transducer.

[0040] The basic principle, main features and advantages of the application are shown and described above. It should be understood by those skilled in the art that the application is not limited by the above-mentioned embodiments, and the above-mentioned embodiments and descriptions in the specification are only preferred examples of the application and are not intended to limit the application. Without departing from the spirit and scope of the application, various changes and improvements can be made to the application, and these changes and improvements all fall within the scope of the claimed application. The scope of protection of the application is defined by the appended claims and their equivalents.

Claims

1. A method for detecting partial discharge based on a distributed capacitive micromachined ultrasonic transducer, characterized in that: The process includes the following: Arrange at least four capacitive micromachined ultrasonic transducers at different positions of the housing of the transformer to be tested, and acquire ultrasonic signals inside the transformer in real time through the capacitive micromachined ultrasonic transducers; The position information of the partial discharge source in the transformer is calculated by using the time information of the ultrasonic signals collected by all capacitive micromachined ultrasonic transducers, the propagation speed of the ultrasonic wave in the transformer and the position information of each capacitive micromachined ultrasonic transducer.

2. The method for detecting partial discharge based on a distributed capacitive micromachined ultrasonic transducer according to claim 1, wherein: It also includes the following processes: Screening out an ultrasonic signal with the largest amplitude from the acquired ultrasonic signals within the transformer; determining a capacitive micromachined ultrasonic transducer that collects the ultrasonic signal with the largest amplitude, and arranging the remaining capacitive micromachined ultrasonic transducers at different positions around the capacitive micromachined ultrasonic transducer that collects the ultrasonic signal with the largest amplitude; The above process is repeated at least once, and then the position information of the partial discharge source in the transformer is calculated using the time information of the ultrasonic signals collected by all capacitive micromachined ultrasonic transducers, the propagation speed of the ultrasonic wave in the transformer, and the position information of each capacitive micromachined ultrasonic transducer.

3. A method for detecting partial discharge based on a distributed capacitive micromachined ultrasonic transducer according to claim 1 or 2, characterized in that: There are four capacitive micromachined ultrasonic transducers, which are respectively denoted as the first capacitive micromachined ultrasonic transducer, the second capacitive micromachined ultrasonic transducer, the third capacitive micromachined ultrasonic transducer and the fourth capacitive micromachined ultrasonic transducer. The spatial coordinates of the first capacitive micromachined ultrasonic transducer, the second capacitive micromachined ultrasonic transducer, the third capacitive micromachined ultrasonic transducer and the fourth capacitive micromachined ultrasonic transducer are respectively denoted as 、 、 and The moments when the first capacitive micromachined ultrasonic transducer, the second capacitive micromachined ultrasonic transducer, the third capacitive micromachined ultrasonic transducer, and the fourth capacitive micromachined ultrasonic transducer receive the ultrasonic signal in the transformer are respectively 、 、 and , the propagation speed of ultrasonic waves in the transformer is , then the spatial coordinates of the partial discharge source in the transformer are Calculated by the following equations: 。 4. A partial discharge detection device based on a distributed capacitive micromachined ultrasonic transducer, characterized in that: A method for detecting partial discharges based on distributed capacitive micromachined ultrasonic transducers, used to implement any one of claims 1-3, comprises at least four capacitive micromachined ultrasonic transducers, all of which are connected to a signal processing module, the signal processing module being used to calculate the position information of the partial discharge source in the transformer using the time information of the ultrasonic signals collected by all the capacitive micromachined ultrasonic transducers, the propagation speed of the ultrasonic waves in the transformer, and the position information of each capacitive micromachined ultrasonic transducer.

5. The partial discharge detection device based on a distributed capacitive micromachined ultrasonic transducer according to claim 4, characterized in that: All capacitive micromachined ultrasonic transducers are wirelessly connected to the signal processing module via a Bluetooth module.

6. The partial discharge detection device based on a distributed capacitive micromachined ultrasonic transducer according to claim 4, characterized in that: For each capacitive micromachined ultrasonic transducer, the capacitive micromachined ultrasonic transducer is arranged in a sensor housing (2), a matching layer (5) is provided at the bottom of the sensor housing (2), the capacitive micromachined ultrasonic transducer is located in the sensor housing (2) and fixed on the matching layer (5), the matching layer (5) is connected to the housing of the transformer, a high-frequency connector (8) is provided on the sensor housing (2), and the capacitive micromachined ultrasonic transducer is connected to the high-frequency connector (8).

7. The partial discharge detection device based on a distributed capacitive micromachined ultrasonic transducer according to claim 6, characterized in that: The sensor housing (2) comprises an outer conical metal housing (3), and a sound-absorbing cotton layer (9) is provided on the inner surface of the conical metal housing (3).

8. The partial discharge detection device based on a distributed capacitive micromachined ultrasonic transducer according to claim 6, characterized in that: The capacitive micromechanical ultrasonic transducer and the matching layer (5) are connected via an adhesive layer (4), and a fixing bracket (6) for fixing the capacitive micromechanical ultrasonic transducer is provided on the adhesive layer (4).

9. The partial discharge detection device based on a distributed capacitive micromachined ultrasonic transducer according to claim 6, characterized in that: The capacitive micromachined ultrasonic transducer includes a packaging shell (71), the bottom of the packaging shell (71) is fixed to a PCB printed circuit board (74) through an adhesive layer (78), a capacitive micromachined ultrasonic transducer chip (73) and an ASIC chip (77) are provided inside the packaging shell (71), the capacitive micromachined ultrasonic transducer chip (73) and the ASIC chip (77) are electrically connected and both are fixed on the adhesive layer (78), the ASIC chip (77) is electrically connected to the PCB printed circuit board (74), the PCB printed circuit board (74) is electrically connected to the high-frequency connector (8), the outside of the ASIC chip (77) is also cast with a potting glue (76), and a sound hole (75) for transmitting sound waves is provided at a position opposite to the capacitive micromachined ultrasonic transducer chip (73) on the top of the packaging shell (71).

10. The partial discharge detection device based on a distributed capacitive micromachined ultrasonic transducer according to claim 9, characterized in that: The capacitive micromachined ultrasonic transducer chip (73) uses a MEMS ultrasonic sensor.

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