EFPI sensor with acoustic directivity control function
By wrapping the acoustic directionality regulation unit and filling the acoustic impedance matching liquid outside the EFPI sensor, the problems of limited acoustic directionality and fragility of the diaphragm are solved, achieving a larger range of efficient sound reception and diaphragm protection, ensuring that Stable detection in high-voltage power equipment.
Patent Information
- Application Number
- CN202410434796.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-04-11
- Publication Date
- 2024-12-10
- Estimated Expiration
- 2044-04-11
AI Technical Summary
The acoustic directionality of the EFPI sensor is limited, resulting in a decrease in the sensitivity of the acoustic signal detection in the non-efficient acoustic reception angle range, and the diaphragm is fragile, making it impossible to effectively detect locally released ultrasonic signals in high-voltage power equipment, and membranes are prone to appear during installation. The chip is broken.
The EFPI sensor is wrapped with an acoustic directional regulation unit, including an N-layer acoustic directional regulation layer, and refracts the local ultrasonic signal through a gradually smaller impedance, guiding it into the efficient response reception interval, increasing the acoustic directionality, and in the membrane A vibration coupling gap is set between the sheet and the acoustic directional regulation unit and acoustic impedance matching liquid is filled to protect the diaphragm.
It significantly expands the high-efficiency sound reception angle of the EFPI sensor, improves detection sensitivity, and provides high-strength protection for fragile diaphragms, avoids diaphragm damage, and ensures stable operation in high-voltage power environment.
Smart Images
Figure CN118191530B_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a technology for improving the acoustic directivity of an EFPI sensor, and belongs to the field of sensors. Background Art
[0002] Partial discharge is the initial manifestation of insulation degradation. The detection of partial discharge of high-voltage power equipment can effectively evaluate the insulation status of the equipment, quickly eliminate dangers, and improve the safety and stability of equipment operation. Therefore, the detection of partial discharge is particularly important. Partial discharge is accompanied by physical phenomena such as sound, light, electricity, heat, and chemistry. Among them, partial discharge ultrasonic signals have become an important detection method for partial discharge due to their strong anti-interference ability, rapid positioning ability of partial discharge points, and high real-time performance. Sensors for partial discharge ultrasonic signal detection mainly include optical acoustic sensors and piezoelectric ceramic (PZT) sensors. Among them, optical sensors have been widely studied due to their strong anti-electromagnetic interference ability, high detection sensitivity, and long transmission distance. Among the many optical ultrasonic sensors, the extrinsic Fabry-Perot (EFPI) sensor has received extensive attention and research due to its detection sensitivity, simple structure, small size, and can be designed as a fully insulating structure for internal installation. However, the diaphragm-type EFPI sensor still has the key problems of small receiving angle of efficient acoustic signals and fragile diaphragm structure.
[0003] The basic structure of EFPI sensor can be found in Figure 1 As shown, it includes a diaphragm 101, a quartz glass tube 102, an optical fiber 103 and a Fabry-Perot cavity 104. The normal direction of the diaphragm is defined as a 0° receiving angle, and the counterclockwise direction is the positive direction. The EFPI sensor has a small high-efficiency acoustic receiving angle, that is, its sensor has obvious acoustic directivity, see Figure 4 The black block describes the curve. The EFPI sensor has two high-efficiency response receiving intervals, one of which is the 300°~60° receiving angle directly opposite the diaphragm, and the other is the 120°~180° receiving angle at the tail end of the optical fiber. The part outside these two intervals is the non-efficient sound receiving angle interval. The detection sensitivity of the EFPI sensor to the sound signal incident in the non-efficient sound receiving angle interval will be greatly reduced, making the sensor unable to effectively detect the partial discharge ultrasonic signal; in order to obtain higher detection sensitivity, the EFPI sensor sound and light transducer diaphragm thickness is generally less than 30 microns. This diaphragm thickness cannot cope with the complex operating environment of high-voltage power equipment, especially when it is installed inside the power transformer to detect partial discharge ultrasonic signals. The diaphragm is very likely to be damaged, which causes the EFPI sensor to fail completely, and even the diaphragm fragments as foreign matter cause insulation accidents. Summary of the invention
[0004] In order to solve the problem of limited receiving angle when using an EFPI sensor to detect partial discharge ultrasonic signals, the present invention provides an EFPI sensor with acoustic directivity control function.
[0005] The EFPI sensor with acoustic directivity control function described in the present invention includes an EFPI sensor 100 and an acoustic directivity control unit, and the acoustic directivity control unit is wrapped around the outside of the EFPI sensor 100; the acoustic directivity control unit includes N layers of acoustic directivity control layers 200, and the impedance of the N layers of acoustic directivity control layers 200 gradually decreases from the outside to the inside. The local discharge ultrasonic signals in different wave vector directions are modulated by the acoustic directivity control unit and enter the high-efficiency response receiving interval of the EFPI sensor. The modulation process is a process in which the N layers of acoustic directivity control layers 200 continuously refract the local discharge ultrasonic signals and guide them to the high-efficiency response receiving interval.
[0006] Preferably, a vibration coupling gap 300 is provided between the diaphragm of the EFPI sensor 100 and the acoustic directivity control unit, and the vibration coupling gap 300 is filled with an acoustic impedance matching liquid.
[0007] Preferably, each layer of the acoustic directivity control layer 200 is a trumpet-shaped structure with the diaphragm normal as the axis of symmetry, wherein the end of the acoustic directivity control unit wrapped around the diaphragm end is arc-shaped, and the longitudinal cross-section is elliptical, and the acoustic directivity control unit is gradually distributed along the direction from the diaphragm end of the EFPI sensor 100 to the tail end of the optical fiber until it shrinks into a cone at the tail end of the optical fiber.
[0008] Preferably, the EFPI sensor 100 has two high-efficiency response receiving sections, which are located at the membrane end and the optical fiber tail end respectively.
[0009] Beneficial effects of the present invention: After the EFPI sensor is installed with an acoustic directivity control unit, its sensing detection characteristics show obvious non-acoustic directivity, that is, the EFPI sensor now obtains a larger range of efficient sound receiving angles. At the same time, the introduction of the acoustic directivity control unit provides high-intensity protection for the fragile diaphragm of the EFPI sensor. BRIEF DESCRIPTION OF THE DRAWINGS
[0010] Figure 1 This is a basic structural diagram of a traditional EFPI sensor;
[0011] Figure 2 It is a structural schematic diagram of the EFPI sensor with acoustic directivity control function according to the present invention;
[0012] Figure 3 is a schematic diagram of a partial discharge signal monitoring system using the EFPI sensor of the present invention;
[0013] Figure 4It is a comparison chart of the acoustic directivity results of monitoring partial discharge signals using the traditional EFPI sensor and the EFPI sensor of the present invention; wherein the black block curve is the acoustic directivity result of monitoring partial discharge signals using the traditional EFPI sensor, and the red block curve is the acoustic directivity result of monitoring partial discharge signals using the sensor of the present invention. DETAILED DESCRIPTION
[0014] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0015] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.
[0016] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.
[0017] Specific implementation method 1: The following is combined Figures 1 to 4 The present embodiment is described. The EFPI sensor with acoustic directivity control function described in the present embodiment includes an EFPI sensor 100 and an acoustic directivity control unit. The acoustic directivity control unit is wrapped around the outside of the EFPI sensor 100. The acoustic directivity control unit includes N layers of acoustic directivity control layers 200. The impedance of the N layers of acoustic directivity control layers 200 gradually decreases from the outside to the inside. The local discharge ultrasonic signals in different wave vector directions are modulated by the acoustic directivity control unit and enter the high-efficiency response receiving interval of the EFPI sensor. The modulation process is a process in which the N layers of acoustic directivity control layers 200 continuously refract the local discharge ultrasonic signals and guide them to the high-efficiency response receiving interval, so as to achieve high-sensitivity reception of the EFPI sensor.
[0018] Each layer of the acoustic directivity control layer 200 is a trumpet-shaped structure with the diaphragm normal as the axis of symmetry, wherein the end of the acoustic directivity control unit wrapped in the diaphragm end is arc-shaped, and the longitudinal cross-section is elliptical, and the acoustic directivity control unit is gradually distributed along the direction from the diaphragm end of the EFPI sensor 100 to the tail end of the optical fiber until it shrinks into a cone at the tail end of the optical fiber, thereby guiding a larger range of sound signals to the high response receiving range of the EFPI sensor.
[0019] See also Figure 1When the diaphragm normal of the EFPI sensor coincides with the wave vector direction of the incident ultrasonic signal (the propagation direction of the sound wave), the sensor diaphragm amplitude is the largest, that is, the sensor output signal is the strongest, and this direction is defined as the 0° receiving angle; when the diaphragm normal and the sound signal wave vector form an angle, the incident sound signal produces a phase difference at different points on the effective vibration area of the diaphragm, resulting in a decrease in the total force of the sound signal on the diaphragm, thereby reducing the amplitude of the diaphragm. As the incident angle increases, the total force gradually decreases, which is most obvious when the angle reaches 90°. When the incident angle increases further until the sound signal is incident from the back of the sensor, the sensor output signal is affected by many factors such as the sensor structure. Figure 4 The changes shown, from Figure 4 It can be seen from the curve that the EFPI sensor 100 has two high-efficiency response receiving intervals, located at the diaphragm end and the fiber tail end within the range of ±60°, where the effect of the acoustic signal incident from the back on the sensor is less than that from the front. The traditional EFPI sensor 100 can effectively receive the acoustic signal transmitted within the high-efficiency response receiving interval, but is insensitive to the acoustic signal incident from the non-high-efficiency acoustic receiving angle interval. In order to solve this problem, this embodiment proposes a solution to wrap an acoustic directivity control unit outside the traditional EFPI sensor 100.
[0020] Since sound signals will be refracted when propagating between media with different impedances, Figure 2 The acoustic signal incident in the non-efficient acoustic receiving angle interval is continuously refracted and guided into the efficient response receiving interval.
[0021] like Figure 3 FIG. 1 is an EFPI sensor acoustic directivity test system using the present embodiment. The system uses a plate-plate electrode as an acoustic signal emission source. However, due to the uncertainty of the partial discharge amount, a PZT sensor is used as a calibration comparison sensor. By adjusting the corresponding angles between the EFPI sensor and the plate-plate electrode, the incidence of acoustic signals at different angles is simulated. First, the acoustic directivity test of the bare EFPI sensor without an acoustic directivity control and protection structure is performed. Then, while ensuring that the experimental conditions remain unchanged, the acoustic directivity test of the EFPI sensor with an acoustic directivity control function of the present embodiment is performed. The results are shown in FIG. Figure 4As shown. The experimental results are normalized results, that is, the maximum peak-to-peak value of the output signal of each EFPI sensor is divided by the maximum peak-to-peak value of the output signal of the PZT sensor, and the output signal ratio of the two sensors when the EFPI sensor is facing the plate-plate electrode is used as the initial ratio, that is, it is normalized to 1 when the receiving angle is 0°. The red block curve is the EFPI acoustic directivity result of the present embodiment with acoustic directivity control function. Through the experimental results, it can be found that after the EFPI sensor is installed with the acoustic directivity control unit, its sensing detection characteristics show obvious non-acoustic directivity, that is, at this time the EFPI sensor obtains a wider range of efficient sound receiving angles, and at the same time, the introduction of the acoustic directivity control unit provides high-intensity protection for the fragile diaphragm of the EFPI sensor.
[0022] Specific implementation method 2: This implementation method further limits implementation method 1, and a vibration coupling gap 300 is set between the diaphragm of the EFPI sensor 100 and the acoustic directivity control unit, and the vibration coupling gap 300 is filled with acoustic impedance matching liquid. In this implementation method, in order to ensure that the diaphragm obtains a better vibration space, a vibration coupling gap 300 is left at the contact position between the innermost acoustic directivity control layer 200 of the acoustic directivity control unit and the diaphragm, and the air gap is filled with acoustic impedance matching liquid to ensure that when the acoustic signal is incident on the diaphragm from the innermost layer of the acoustic directivity control unit, there will be no situation where the reflected acoustic signal energy is greater than the incident acoustic signal energy due to acoustic impedance mismatch.
[0023] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. It should therefore be understood that many modifications may be made to the exemplary embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in a manner different from that described in the original claims. It should also be understood that the features described in conjunction with a single embodiment may be used in other described embodiments.
Claims
1. EFPI sensor with acoustic directivity control function, It is characterized in that The invention comprises an EFPI sensor (100) and an acoustic directivity control unit, wherein the acoustic directivity control unit is wrapped around the outside of the EFPI sensor (100); the acoustic directivity control unit comprises N layers of acoustic directivity control layers (200), the impedance of the N layers of acoustic directivity control layers (200) gradually decreases from the outside to the inside, and partial discharge ultrasonic signals in different wave vector directions are modulated by the acoustic directivity control unit and enter the high-efficiency response receiving interval of the EFPI sensor, and the modulation process is a process in which the N layers of acoustic directivity control layers (200) continuously refract the partial discharge ultrasonic signals, and guide the partial discharge ultrasonic signals incident in the non-high-efficiency acoustic receiving angle interval to the high-efficiency response receiving interval; Each layer of the acoustic directivity control layer (200) is a trumpet-shaped structure with the normal direction of the diaphragm as the axis of symmetry, wherein the end of the acoustic directivity control unit wrapped at the end of the diaphragm is arc-shaped, and the longitudinal section is elliptical, and the acoustic directivity control unit is gradually distributed along the direction from the diaphragm end of the EFPI sensor (100) to the tail end of the optical fiber until the tail end of the optical fiber shrinks into a cone.
2. The EFPI sensor with acoustic directivity control function according to claim 1, It is characterized in that A vibration coupling gap (300) is provided between the diaphragm of the EFPI sensor (100) and the acoustic directivity control unit, and the vibration coupling gap (300) is filled with an acoustic impedance matching liquid.
3. The EFPI sensor with acoustic directivity control function according to claim 1, It is characterized in that The EFPI sensor (100) has two high-efficiency response receiving sections, which are respectively located at the membrane end and the optical fiber tail end.