Device and method for testing vibration environment reliability of optical microphone

Abstract

The invention relates to an optical microphone vibration environment reliability test device and test method, and belongs to the technical field of power equipment detection. The device comprises a test box body, a vibration simulation system, an oil-immersed environment simulation system, an ultrasonic signal generation system and an optical microphone fixing part, and can simulate the multi-axial vibration working condition of the oil-immersed transformer in a range of 1-600Hz at high precision. The testing method of the scheme comprises the following steps: testing the change rule of the sensitivity and the signal-to-noise ratio of the optical microphone along with vibration parameters in a simulated oil immersion vibration environment; the method comprises the following steps: quantitatively measuring cavity length drift of a Fabry-Perot interference cavity caused by vibration by using a laser interferometer, and establishing a cavity length-frequency mapping model; and carrying out a reflecting diaphragm durability test and an optical fiber bending loss test, and evaluating the performance attenuation and the service life under long-term vibration. According to the invention, the blank in the prior art is filled, and a systematic evaluation basis is provided for reliable application of the optical microphone in the transformer.

Description

Technical Field

[0001] This invention relates to the field of power equipment testing technology, and in particular to an optical microphone vibration environment reliability testing device and testing method. Background Technology

[0002] Partial discharge is a significant indicator of insulation degradation in power equipment. While it may not immediately cause short circuits or insulation breakdown, its long-term effects gradually corrode the insulation materials, leading to a continuous decline in insulation performance and ultimately insulation failure. Therefore, partial discharge detection of critical power equipment such as transformers can identify potential insulation problems in advance, preventing sudden failures caused by insulation degradation. This is of great importance for reducing power outages and ensuring the safe and stable operation of the power grid.

[0003] Fabry-Pérot (FP) interferometric fiber optic sensors (also known as optical microphones) are widely used in ultrasonic signal detection of partial discharge inside transformers due to their outstanding advantages such as small size, flexible installation, strong anti-electromagnetic interference capability, high positioning accuracy, and high sensitivity.

[0004] However, the internal operating conditions of large oil-immersed transformers are complex, especially the vibration caused by factors such as core magnetostriction, which poses a serious challenge to the long-term detection reliability of the built-in optical microphone. Specifically, the vibration during transformer operation mainly affects the performance of the optical microphone through the following mechanisms: First, vibration causes minute displacements or deformations in the two reflecting surfaces of the FP interferometer cavity, the core sensing unit of the optical microphone, altering its initial cavity length. This directly causes a drift in the wavelength or phase of the interference spectrum, resulting in measurement errors. In severe cases, non-uniform vibration can cause the reflecting surfaces to tilt slightly, reducing their parallelism and leading to a decrease in the contrast of the interference fringes. This, in turn, reduces the signal-to-noise ratio and may even cause the detection signal to disappear completely.

[0005] Secondly, prolonged exposure to vibration can cause fatigue and loosening of the optical microphone's mounting structure, leading to overall displacement or complete detachment of the sensor and its failure. Simultaneously, in a vibrating environment, the highly reflective dielectric film coated on the optical microphone's reflective surface may peel off due to friction or impact from tiny particles in the transformer oil, reducing reflectivity and weakening the reflected signal strength. This not only affects real-time detection performance but also accelerates diaphragm aging and shortens the sensor's lifespan.

[0006] Furthermore, vibration can also affect optical transmission through mechanical conduction. When vibration is transmitted to the fiber optic link connected to the optical microphone, it may cause local bending of the fiber, resulting in attenuation of optical power and further reducing the signal-to-noise ratio of the entire detection system.

[0007] Currently, testing of optical microphone performance largely focuses on evaluating basic acoustic characteristics in static or air environments, lacking a systematic testing scheme for their long-term reliability in the specific vibration environment of oil-immersed transformers. This gap makes it difficult to assess the applicability and lifespan of optical microphones under real-world conditions, hindering their further reliable application in this field.

[0008] Therefore, there is an urgent need for a dedicated testing device and corresponding testing scheme that can highly simulate the vibration conditions of oil-immersed transformers, so as to scientifically evaluate the influence of the vibration environment on the detection performance of optical microphones, fill the existing technological gap, and provide key data support and theoretical basis for the long-term reliable operation and placement optimization of optical microphones in oil-immersed transformers. Summary of the Invention

[0009] The technical problem to be solved by the present invention is: in order to overcome the above-mentioned technical problems, the present invention provides an optical microphone vibration environment reliability testing device and testing method.

[0010] The technical solution adopted by this invention to solve its technical problem is: an optical microphone vibration environment reliability testing device, comprising: The test chamber contains a sealed test cavity. The vibration simulation system includes a vibration table installed at the bottom of the test chamber for generating controllable mechanical vibrations to cause the test chamber to vibrate. An oil immersion environment simulation system includes a transformer oil inlet and outlet located on the test chamber; An ultrasonic signal generating system includes a high-voltage sleeve installed on the top of the test chamber and a partial discharge model placed inside the test cavity, for generating stable ultrasonic signals in an oil immersion environment; An optical microphone fixing component is disposed inside the test cavity and is used to fix the optical microphone to be tested; The test chamber is equipped with a through-hole, through which the optical microphone signal line is introduced into the test chamber. The device is configured to simulate the vibration conditions of an oil-immersed transformer and to perform reliability testing on the optical microphone placed therein.

[0011] The pass-through includes a housing, an optical fiber transmission assembly, and a quick-install sealing mechanism. The housing has cavities extending through both ends. The optical fiber transmission assembly includes an optical fiber patch cord and a potting compound. The patch cord passes through the cavity, and the potting compound is located within the cavity and seals the patch cord within it. The optical microphone signal line is connected to the patch cord of the pass-through. The quick-install sealing mechanism is mounted on the housing and is used to detachably fix the housing to the adapter plate of the oil-immersed transformer and achieve a seal. The quick-install sealing mechanism includes a movable rod, a connecting rod, and at least two openable spring clips. The movable rod is movably mounted on the housing along its axial direction. The spring clips are linked to the movable rod via the connecting rod. When the movable rod is pushed inwards towards the transformer, the spring clips close to allow the pass-through to pass through the adapter plate. When the movable rod is pulled outwards towards the transformer, the movable rod moves outwards towards the transformer, and the connecting rod causes the spring clips to open and press tightly against the inner wall of the transformer, achieving a compression seal.

[0012] The oil immersion environment simulation system also includes an oil pump, which is connected to the inlet and outlet and is used to fill and discharge transformer oil into the test chamber.

[0013] The vibration simulation system has a vibration frequency adjustment range of 1Hz to 600Hz, with a frequency adjustment accuracy of not less than 0.1Hz; a vibration amplitude range of 0 to 5mm; and an acceleration range of 0 to 20g.

[0014] The vibration simulation system supports independent or mixed vibrations along the X, Y, and Z axes of the test chamber. The X, Y, and Z axes correspond to the length, width, and height directions of the test chamber, respectively, with the length direction of the test chamber being longer and the width direction being shorter.

[0015] The penetrator is located on the side of the test chamber.

[0016] The test chamber also has an observation window on its side.

[0017] A method for testing the vibration environment reliability of an optical microphone based on the aforementioned device includes at least one of the following tests: Acoustic performance testing under vibration environment, interference cavity stability testing, reflective diaphragm durability testing, and fiber optic bending loss testing under vibration conditions; The acoustic performance test under vibration environment includes the following steps: The optical microphone to be tested is fixed inside the test cavity; Transformer oil is injected into the test chamber through the oil immersion environment simulation system. The lowest liquid level of the transformer oil injected into the test chamber during vibration is higher than the highest point of the optical microphone, ensuring that the optical microphone can be submerged during vibration. The ultrasonic signal generating system generates a stable ultrasonic signal. The vibration simulation system is controlled to vibrate at a preset vibration frequency, amplitude, and acceleration; The signal-to-noise ratio and sensitivity of the optical microphone were measured under different vibration parameters; The signal-to-noise ratio and sensitivity of the optical microphone were analyzed as a function of vibration parameters. The vibration parameters include vibration frequency, amplitude, acceleration, and vibration direction; The stability test of the interference cavity includes the following steps: The optical microphone to be tested is fixed inside the test cavity; Transformer oil is injected into the test chamber through the oil immersion environment simulation system. The lowest liquid level of the transformer oil injected into the test chamber during vibration is higher than the highest point of the optical microphone, ensuring that the optical microphone can be submerged during vibration. Before the vibration begins, the initial cavity length of the Fabry-Perot interferometer cavity of the optical microphone is measured using a laser interferometer; The vibration simulation system is activated, and the change in cavity length of the optical microphone is measured at different vibration frequencies. The drift of the interference spectrum is recorded using a spectrometer. A mapping model between cavity length offset and vibration frequency was established to analyze the variation of cavity length with vibration frequency. The durability test of the reflective film includes the following steps: The optical microphone to be tested is fixed inside the test cavity; Transformer oil is injected into the test chamber through the oil immersion environment simulation system. The lowest liquid level of the transformer oil injected into the test chamber during vibration is higher than the highest point of the optical microphone, ensuring that the optical microphone can be submerged during vibration. Start the vibration simulation system to perform continuous vibration; At predetermined time intervals, the surface morphology of the optical microphone reflective diaphragm is observed using a microscope, and the peeling area is calculated; at the same time, the reflectivity of the optical microphone reflective diaphragm is measured using a spectrophotometer, and the reflectivity attenuation rate is calculated. The variation of the peeling area and reflectivity attenuation rate with vibration time was analyzed to evaluate the lifespan of the optical microphone; The fiber bending loss test under vibration conditions includes the following steps: A section of fiber optic patch cord simulating the actual deployment state is bent and fixed inside the test cavity. In normal use, the tail fiber of the fiber optic sensor is bent, which simulates this actual bent deployment state. Connect the laser source to the input end of the fiber optic patch cord and connect the optical power meter to the output end of the fiber optic patch cord. Transformer oil is injected into the test chamber through the oil immersion environment simulation system. The lowest liquid level of the transformer oil injected into the test chamber during vibration is higher than the highest point of the optical microphone, ensuring that the optical microphone can be submerged during vibration. Controlling the vibration simulation system to perform frequency sweep vibration, step-type frequency sweep vibration can be preferred; Record the optical power under static conditions And the dynamic optical power P(f) at different vibration frequencies f; Calculate the frequency attenuation rate and frequency attenuation coefficient of optical power, analyze the law of optical power attenuation with vibration frequency, and locate the critical failure frequency. Specifically, based on experiments, continuously reduce the frequency until the sensor can no longer detect the position. The frequency at this point is the critical failure frequency.

[0018] When the vibration simulation system supports independent or mixed vibrations in the X, Y, and Z axes of the test chamber, the optical microphone vibration environment reliability test method includes multi-axial vibration effect testing. The multiaxial vibration effect test includes the following steps: Multiple optical microphones to be tested are fixed inside the test cavity; Transformer oil is injected into the test chamber through the oil immersion environment simulation system. The lowest liquid level of the transformer oil injected into the test chamber during vibration is higher than the highest point of the optical microphone, ensuring that the optical microphone can be submerged during vibration. The ultrasonic signal generating system generates a stable ultrasonic signal. The vibration simulation system is controlled to apply vibrations in the X, Y, and Z axes respectively, and the signal-to-noise ratio and sensitivity of the optical microphone under different vibration directions are tested and recorded respectively; and / or the vibration simulation system is controlled to apply vibrations in the X, Y, and Z axes simultaneously, and the signal-to-noise ratio and sensitivity of the optical microphone are tested and recorded. The impact of vibration direction on the detection performance of the optical microphone was evaluated.

[0019] When testing acoustic performance or interference cavity stability under vibration, the vibration frequency starts from 1 Hz and gradually increases to 600 Hz in 50 Hz increments.

[0020] Compared with the prior art, the optical microphone vibration environment reliability testing device and testing scheme provided by the present invention have the following significant advantages: 1. This invention constructs a highly realistic transformer operating environment within a sealed testing device by integrating a mechanical vibration table, an oil-immersed environment simulation system, and a high-voltage discharge ultrasonic signal generation system. This device not only simulates the transformer oil medium environment but also accurately reproduces the main frequency components of transformer core vibration, including the 50Hz power frequency and its higher harmonics, with a frequency range of 1-600Hz, as well as multi-directional vibration characteristics. This solves the problem that traditional vibration tests are only conducted in air and cannot reflect the true operating conditions of oil-immersed transformers, providing a reliable testing platform for optical microphones.

[0021] 2. This invention is not only a testing device, but also proposes a complete testing scheme based on the device, which can quantitatively evaluate the impact of vibration on the performance of optical microphones from multiple key dimensions: Acoustic performance evaluation: It can test the changes in sensitivity and signal-to-noise ratio of optical microphones under different vibration frequencies, amplitudes, accelerations and directions, and directly evaluate the stability of its detection performance.

[0022] Interference cavity stability assessment: By combining a laser interferometer and a spectrometer, the changes in cavity length and interference spectrum drift caused by vibration were quantitatively measured, and a mapping model of "cavity length offset - vibration frequency" was constructed, providing a direct basis for analyzing the stability of the core sensing unit of the sensor.

[0023] Durability assessment of key components: By simulating long-term vibration, the evolution of the reflectivity attenuation rate and surface peeling area of ​​the optical microphone reflective diaphragm over time is quantitatively monitored, enabling accelerated assessment and prediction of the optical microphone's lifespan.

[0024] Fiber optic transmission reliability assessment: By testing the optical power attenuation of bent optical fibers under vibration conditions, the critical failure frequency is located, and the impact of vibration on the signal transmission link is evaluated, providing guidance for on-site cabling.

[0025] 3. The vibration simulation system of this invention has a high vibration frequency adjustment accuracy of 0.1Hz, and the amplitude and acceleration can be precisely controlled. It also supports independent or mixed vibrations in the X, Y, and Z axes. This high-precision, multi-degree-of-freedom control capability enables the test to finely simulate various complex vibration scenarios, resulting in more accurate test results and stronger guidance.

[0026] 4. This invention systematically solves the problem of the lack of a dedicated reliability testing scheme for optical microphones in the vibration environment of oil-immersed transformers. The test data obtained through this device and scheme can provide key data support and theoretical basis for the optimized placement of optical microphones in transformers, vibration-resistant structure design, service life prediction, and field application reliability assessment, which is of great significance for promoting the reliable application of optical microphones in power equipment condition monitoring. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the reliability testing device provided in an embodiment of the present invention.

[0028] Figure 2 This is a schematic diagram illustrating the cascade effect of vibration on the performance of an optical microphone, as described in this invention.

[0029] Figure 3 This is a flowchart of the reliability testing method provided in the embodiments of the present invention.

[0030] Figure 4 This is a diagram illustrating the specific test steps of the acoustic performance testing method under vibration environment provided in this embodiment of the invention.

[0031] Figure 5 This is a schematic diagram of the overall structure of the penetrator provided in an embodiment of the present invention.

[0032] Figure 6 This is a partially enlarged schematic diagram of the fiber optic patch cord encapsulated within the housing in this invention.

[0033] Figure 7 This is a schematic diagram of the installation process of the penetrator provided in an embodiment of the present invention.

[0034] In the diagram: 1. Test chamber, 2. Vibration table, 3. High-voltage bushing, 4. Partial discharge model, 5. Observation window, 6. Optical microphone, 7. Optical microphone signal line, 8. Optical microphone fixing component, 9. Transformer oil inlet / outlet, 10. Through-connector, T1. Fiber optic patch cord, T2. Fiber optic interface, T3. Flange, T4. Inner sleeve, T41. Potting body, T5. Outer shell, T6. Adapter plate, T7. Spring, T8. Pivot point, T9. Connecting ring, T10. Push rod, T11. Connecting rod, T12. Sealing ring, T13. Thread, T14. Fixing nut, T15. Return spring, T16. Locking block, a. Transformer inner side. Detailed Implementation

[0035] The invention will now be described in further detail with reference to the accompanying drawings. It should be emphasized that the following description is merely exemplary and not intended to limit the scope or application of the invention.

[0036] Example 1

[0037] like Figure 1 As shown, this embodiment provides an optical microphone vibration environment reliability testing device, which mainly consists of the following parts: Test Chamber 1: As the core container, its interior forms a sealed test chamber to simulate the internal environment of a transformer tank. The chamber is typically made of high-strength metals, such as stainless steel, to ensure structural strength and sealing.

[0038] Vibration simulation system: Its core is the vibration table 2 located at the bottom of the test chamber 1. This vibration table 2 can be electromagnetic or hydraulic, with a vibration frequency adjustment range of 1Hz to 600Hz, accurately covering the 50Hz power frequency of the transformer and its higher harmonics. The vibration frequency adjustment accuracy is no less than 0.1Hz, and the screen display accuracy can reach 0.01Hz. The vibration amplitude range is 0 to 5mm, and the acceleration range is 0 to 20g. More importantly, this vibration table 2 supports independent or mixed vibrations along the X, Y, and Z axes of the test chamber 1 to simulate real and complex multi-dimensional vibration conditions.

[0039] Oil immersion environment simulation system: includes transformer oil inlet and outlet located at the bottom of the test chamber 1 and an external oil pump connected to the inlet and outlet. The oil pump can quickly fill and drain transformer oil into the test chamber, enabling the optical microphone 6 to be tested in an oil immersion state, and allowing for convenient replacement of internal components. Figure 1 The location shown in Figure 9 is the transformer oil inlet or outlet. The transformer oil inlet and outlet are located on the same side, but they are separate.

[0040] Ultrasonic signal generation system: This includes a high-voltage sleeve 3 fixedly mounted on the top of the housing and a partial discharge model 4, such as a needle-plate discharge model, placed inside the test chamber. By applying a high voltage of a specific intensity, such as a sinusoidal AC voltage, to the high-voltage sleeve 3, a stable and repeatable ultrasonic signal can be excited at the discharge model 4, which is used to evaluate the detection performance of the optical microphone 6.

[0041] Optical microphone mounting component 8: Located inside the test chamber, it can be a mechanical clamp or a customized mounting base, used to reliably mount and fix the optical microphone 6 under test, and its position and orientation can be adjusted to simulate different deployment scenarios. The clamp can be set according to the sensor size, which should fix the sensor but not put too much pressure on it to avoid affecting the sensor's performance, since the sensor relies on the vibration of the diaphragm to achieve sensing.

[0042] Through-connector 10: Located on the side of the test chamber 1. The fiber optic signal line of the optical microphone 6 is introduced into / exited from the test chamber 1 through the through-connector 10, while ensuring the high sealing of the chamber and preventing transformer oil leakage.

[0043] Observation window 5: Also located on the side of the test chamber 1, it is usually made of high-strength transparent glass, which makes it easy for the experimenters to observe the internal working conditions of the device, confirm the status of the optical microphone 6, and assist in replacing the internal discharge model 4.

[0044] like Figure 5As shown, the penetrator 10 provided in this embodiment of the invention includes a housing, an optical fiber transmission assembly, and a quick-install sealing mechanism. The housing has an accommodating cavity extending through both ends; the optical fiber transmission assembly includes an optical fiber patch cord T1 and a potting compound T41. The optical fiber patch cord T1 penetrates the accommodating cavity and transmits the sensor's detection signal to an external demodulation system with low optical loss, thereby realizing the transmission of optical signals. The potting body T41 is located within the accommodating cavity and pots the fiber optic patch cord T1 within the accommodating cavity. The optical microphone signal line 7 is connected to the fiber optic patch cord T1 of the pass-through device 10. A quick-install sealing mechanism is provided on the housing to detachably fix the housing to the adapter plate T6 of the oil-immersed transformer and achieve sealing. The quick-install sealing mechanism includes a movable rod, a connecting rod T11, and at least two openable spring pieces T7. The movable rod is movably disposed on the housing along the axial direction of the housing. The spring pieces T7 are linked to the movable rod through the connecting rod T11. When the movable rod is pushed inward toward the transformer, the spring pieces T7 are closed to allow the pass-through device to pass through the adapter plate T6. When the movable rod is pulled outward toward the transformer, the movable rod moves in the direction of the transformer's outward direction, and the connecting rod T11 drives the spring pieces T7 to open and press tightly against the inner wall of the transformer to achieve a compression seal.

[0045] The fiber optic interface T2 of the fiber optic patch cord T1 is preferably an FC type interface to avoid the interface being too long and protruding, causing partial discharge inside the transformer.

[0046] like Figure 6 As shown, the potting height of the potting body T41 is flush with the end face of the outer shell, ensuring high sealing performance inside the connector 10. During potting, potting is performed on both sides of the flange T3 of the FC type interface to facilitate connection with the optical fiber. The potting body T41 is made of high-temperature and oil-resistant epoxy resin. When forming the potting body T41, silicone is first used to pre-fix the optical fiber patch cord T1 to maintain its shape, and then epoxy resin potting is performed. This avoids excessive bending and excessive compression of the optical fiber patch cord T1 during epoxy resin condensation and curing, which would increase optical loss.

[0047] The quick-install sealing mechanism also includes a sealing ring T12 and a fixing nut T14. When the spring T7 opens and is pressed against the inner wall of the transformer, the sealing ring T12 is compressed between the adapter plate T6 and the outer shell and / or between the adapter plate T6 and the fixing nut T14. The fixing nut T14 is sleeved on the outer shell and threadedly connected to the outer shell.

[0048] The ferrule of the fiber optic patch cord T1 is preferably a glass ferrule, and the outer surface of the glass ferrule is covered with a titanium dioxide coating. The titanium dioxide coating is formed on the surface of the glass ferrule by spraying or vapor deposition.

[0049] The outer casing includes an inner sleeve T4 and an outer shell T5 coaxially fitted together, with a gap between the inner sleeve T4 and the outer shell T5. The movable rod and connecting rod 11 are disposed within the gap, and the potting body T41 is enclosed within the inner sleeve T4. Both the inner sleeve T4 and the outer shell T5 are made of stainless steel. The gap between the inner sleeve T4 and the outer shell T5 is filled with air to facilitate the sliding of the movable rod, thereby controlling the opening state of the spring T7.

[0050] The movable rod includes a connecting ring T9 and multiple push rods T10. The push rods T10 are arranged along the axial direction of the outer shell and are evenly distributed between the inner sleeve T4 and the outer shell T5. The connecting ring T9 is located at the end away from the spring T7, and one end of each push rod T10 is connected to one end of the spring T7 via a connecting rod T11. The other end of each push rod T10 is fixedly connected to the connecting ring T9. The outer shell is also provided with a locking assembly, which includes a return spring T15 and a locking block T16. One end of the return spring T15 is fixed to the inner sleeve T4, and the other end of the return spring T15 is fixed to the locking block T16. The return spring T15 is arranged perpendicular to the axial direction of the outer shell. The locking block T16 moves radially along the outer shell through the return spring T15. When the movable rod is pulled outward towards the outside of the transformer, the spring T7 opens and presses tightly against the inner wall of the transformer. The locking block T16 pushes the inner wall of the connecting ring T9 outward and locks with the connecting ring T9, thereby locking the push rod T10. In this embodiment, the connecting ring T9 is a circular ring shape, which is fitted onto the optical fiber connector. The connecting ring T9 and the push rod T10 are a whole.

[0051] like Figure 7 As shown, the push rod T10 moves to the left, causing the spring piece T7 to move and close, making it easier for the penetrator to pass through the adapter plate T6 and enter the transformer. Then, the connecting ring T9 is stretched to the right, pulling the push rod T10. The connecting rod T11 causes the spring piece T7 to move and open. The entire penetrator is moved to the right to ensure that the spring piece T7 is tightly attached to the inner wall of the transformer. The rubber sealing ring T12 is used to ensure a seal, and the fixing nut T14 is tightened to fix the penetrator and complete the installation.

[0052] Example 2

[0053] This embodiment details the implementation process of several core testing methods based on the above-mentioned device. The overall process can be found in [reference needed]. Figure 3 .

[0054] 1. Acoustic performance testing under vibration conditions, such as... Figure 4 As shown: Step S101: Install the optical microphone 6 to be tested into a predetermined position inside the test chamber using the optical microphone fixing component 8.

[0055] Step S102: Inject transformer oil into the test chamber using an oil immersion environment simulation system until the optical microphone 6 is completely submerged. To ensure that the optical microphone 6 is submerged during vibration, the lowest level of the transformer oil injected into the test chamber during vibration is higher than the highest point of the optical microphone 6.

[0056] Step S103: Apply a stable sinusoidal voltage to the partial discharge model 4 through the high-voltage bushing 3 to generate a stable ultrasonic signal.

[0057] Step S104: Set the parameters of the vibration table 2, for example: amplitude 3mm, acceleration 10g. Start with a vibration frequency of 1Hz and gradually increase the vibration frequency to 600Hz in 50Hz intervals. Before this step, the signal-to-noise ratio and sensitivity of the output signal of the optical microphone 6 when it is not vibrating can be tested first. This can be used as a benchmark for subsequent experiments. All subsequent experiments will apply the same ultrasonic signal for comparison. In specific tests, vibration signals of different intensities can be applied in the X-axis direction.

[0058] Step S105: At each frequency point, after the vibration stabilizes, measure and record the signal-to-noise ratio and sensitivity of the output signal of the optical microphone 6 through the back-end data acquisition system. This allows testing the changes in the signal-to-noise ratio and sensitivity of the optical microphone 6 at different locations within the device, and evaluating the impact of the vibration source on the test performance of the optical microphone at different locations in the same vibration environment.

[0059] Step S106: Plot the signal-to-noise ratio-vibration frequency and sensitivity-vibration frequency relationship curves to analyze the law of change of acoustic performance of optical microphone 6 with vibration frequency.

[0060] 2. Multiaxial vibration effect test

[0061] When the vibration simulation system supports independent or mixed vibrations in the X, Y, and Z axes of the test chamber 1, the vibration environment reliability test method for the optical microphone 6 includes this multi-axial vibration effect test, which can be implemented after step S104. The same vibration signal is applied in the X, Y, and Z axes respectively, and the signal-to-noise ratio and sensitivity of the optical microphone 6 are tested to evaluate the impact of different vibration directions on the optical microphone test performance. Finally, three-dimensional vibration is applied simultaneously to highly simulate the impact of complex vibration environment on the optical microphone, specifically including the following steps: Step S201: To keep the ultrasonic signal stable, fix multiple optical microphones 6 at different positions inside the test chamber.

[0062] Step S202: Fix the vibration intensity, amplitude 3mm, and acceleration 10g.

[0063] Step S203: Starting from 1Hz, at 50Hz intervals, the vibration table 2 applies vibrations to the X, Y, and Z axes of the test chamber 1 respectively, and measures and records the signal-to-noise ratio of each optical microphone 6 under different vibration directions.

[0064] Step S204: Compare and analyze the data to evaluate the impact of vibration direction on the detection performance of optical microphone 6, and provide a basis for the selection of on-site placement location.

[0065] 3. Interference cavity stability test

[0066] Step S301: Fix the optical microphone 6 inside the test chamber and inject transformer oil. To ensure that the optical microphone 6 is submerged during vibration, the lowest level of the transformer oil injected into the test chamber during vibration is higher than the highest point of the optical microphone 6.

[0067] Step S302: When there is no vibration, use a laser interferometer to perpendicularly incident the beam into the Fabry-Perot FP interferometer cavity of the optical microphone 6 and measure its initial cavity length as a reference.

[0068] Step S303: Start the vibration table 2 and perform step sweep vibration from 1Hz to 600Hz at 50Hz intervals.

[0069] Step S304: At each frequency point, the change in cavity length of the FP cavity is measured in real time using a laser interferometer, and the drift of the interference spectrum is recorded simultaneously using a spectrometer.

[0070] Step S305: Plot the relationship between cavity length offset and vibration frequency, construct a quantitative mapping model, and analyze the stability of the 6 core sensing units of the optical microphone as a function of vibration frequency.

[0071] 4. Durability test of reflective film

[0072] Step S401: Fix the optical microphone 6 inside the test chamber and inject transformer oil until the optical microphone 6 is completely submerged during vibration.

[0073] Step S402: Set the vibration table 2 to vibrate continuously for a long time at a frequency of 50Hz and an acceleration of 10g.

[0074] Step S403: Every 24 hours, take pictures of the surface morphology of the reflective film through the observation window 5 using a microscope, and calculate the peeling area. .

[0075] Step S404: Measure the reflectance of the film using a spectrophotometer and calculate the reflectance attenuation rate. .

[0076] Step S405: Record the changes in peeling area and reflectivity attenuation rate with vibration time, plot the curves, analyze the aging rate of the diaphragm, and provide a basis for predicting the service life of the optical microphone 6 in a vibration environment.

[0077] 5. Fiber bending loss test under vibration conditions

[0078] Step S501: Bend a section of fiber optic patch cord to simulate the actual deployment state and fix it in the test cavity. The bending degree of the fiber optic patch cord should not be too large to avoid affecting the transmission of optical signals. In normal use, the tail fiber of the fiber optic sensor is bent, which is to simulate this actual bending deployment state.

[0079] Step S502: Connect the laser source to the input end of the fiber optic patch cord and connect the optical power meter to the output end of the fiber optic patch cord.

[0080] Step S503: Inject transformer oil into the test chamber. To ensure that the optical microphone 6 can be submerged during vibration, the lowest level of the transformer oil injected into the test chamber during vibration is higher than the highest point of the optical microphone 6.

[0081] Step S504: Set the vibration table 2 to sweep frequency in 1Hz steps, set the step duration to 30s, and set the acceleration to 10g.

[0082] Step S505: Record the output optical power under static conditions. And the dynamic optical power P(f) at different vibration frequencies f.

[0083] Step S506: Calculate the frequency attenuation rate of optical power and frequency attenuation coefficient This study analyzes the relationship between optical power attenuation and vibration frequency to pinpoint the critical failure frequency at which optical power drops sharply, guiding on-site fiber optic cabling. Specifically, based on experiments, the frequency is continuously reduced until the sensor can no longer detect the location; this frequency is the critical failure frequency.

[0084] Figure 2This invention relates to a schematic diagram of the cascade effect of vibration on the performance of an optical microphone. Transformer vibration may cause displacement of the reflective surface of the FP cavity, changing the initial cavity length, leading to wavelength drift in the interference spectrum, phase signal distortion, and reduced detection sensitivity. Non-uniform vibration causes a slight tilt of the reflective surface, reducing parallelism, decreasing interference fringe contrast, and thus reducing the signal-to-noise ratio. Therefore, this invention proposes a reliability testing scheme for the stability of the optical microphone's interference cavity in a vibration environment. The optical microphone 6 is fixed on the experimental stage inside the device, and the cavity length of the optical microphone 6 is measured by perpendicularly incident laser interferometer beam into the FP cavity, recorded as reference data. The vibration stage 2 is started, and the change in the cavity length of the optical microphone 6 is measured at 50Hz intervals from 1Hz to 600Hz. The amount of interference spectrum drift is analyzed and recorded using a spectrometer, and a cavity length offset-vibration frequency graph is plotted to analyze the law of change of the cavity length of the optical microphone 6's reflective cavity with the transformer vibration frequency. At the same time, the signal-to-noise ratio of the optical microphone 6 is tested under the same ultrasonic signal, and a signal-to-noise ratio-vibration frequency waveform is plotted to analyze the law of change of the detection signal-to-noise ratio of the optical microphone 6 with the transformer vibration frequency, providing a basis for the reliable application of the optical microphone 6.

[0085] Long-term vibration in transformer oil can cause friction or peeling of the reflective film particles, reducing reflectivity, weakening signal strength, accelerating diaphragm aging, and shortening diaphragm lifespan. Therefore, this invention conducts durability tests on the reflective film. The optical microphone 6 is fixed in a test chamber, and transformer oil is injected until it is completely submerged during vibration. The vibration table 2 is started at a vibration frequency of 50Hz and an acceleration of 10g. The surface morphology of the film is photographed with a microscope every 24 hours, and the reflectivity of the film is measured with a spectrophotometer. The peeling area and reflectivity attenuation rate are calculated, and the changes in the peeling area and reflectivity attenuation rate with vibration time are analyzed to provide a basis for the life assessment of the optical microphone 6 in the transformer vibration environment.

[0086] When optical microphone 6 is arranged inside a transformer, it is often in a bent state. Under vibration conditions, this may increase optical power loss. Therefore, this invention conducts an optical power loss test under vibration conditions to measure the correlation between vibration frequency and fiber bending loss, and to locate the critical failure frequency. A section of fiber optic patch cord is fixed in a bent shape inside the test box to simulate the actual arrangement of optical microphone 6. A laser source is connected to the input end of the fiber optic patch cord, and an optical power meter is connected to the output end of the fiber optic patch cord. The vibration table 2 is set to sweep the frequency in 1Hz steps, with a step time of 30s and an acceleration of 10g. The static optical power P and dynamic optical power P(f) are recorded, and the frequency attenuation rate and frequency attenuation coefficient are calculated to explore the law of optical power attenuation changing with vibration frequency.

[0087] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A device for testing the reliability of an optical microphone under vibration conditions, characterized in that, include: The test chamber (1) has a sealed test cavity inside; The vibration simulation system includes a vibration table (2) disposed at the bottom of the test chamber (1) for generating mechanical vibration; An oil immersion environment simulation system includes a transformer oil inlet and outlet located on the test chamber (1); An ultrasonic signal generating system includes a high-voltage sleeve (3) installed on the top of the test chamber (1) and a partial discharge model (4) placed inside the test chamber, for generating ultrasonic signals in an oil immersion environment; An optical microphone fixing component (8) is disposed in the test cavity and is used to fix the optical microphone (6) to be tested. The test chamber (1) is equipped with a through-hole (10), and the optical microphone signal line (7) is introduced into the test chamber (1) through the through-hole (10). The device is configured to simulate the vibration condition of an oil-immersed transformer and to perform reliability testing on the optical microphone (6) placed therein.

2. The optical microphone vibration environment reliability testing device as described in claim 1, characterized in that: The penetrator (10) includes a housing, an optical fiber transmission assembly, and a quick-install sealing mechanism; The outer shell has an accommodating cavity extending through both ends thereto; The optical fiber transmission assembly includes an optical fiber patch cord (T1) and a potting compound (T41). The optical fiber patch cord (T1) passes through the accommodating cavity, and the potting compound (T41) is located inside the accommodating cavity and pots the optical fiber patch cord (T1) inside the accommodating cavity. The optical microphone signal line (7) is connected to the optical fiber patch cord (T1) of the connector (10). The quick-install sealing mechanism is disposed on the outer casing and is used to detachably fix the outer casing to the transition plate of the oil-immersed transformer and achieve a seal. The quick-install sealing mechanism includes a movable rod, a connecting rod (T11), and at least two openable spring pieces (T7). The movable rod is movably disposed on the outer casing along the axial direction of the outer casing. The spring pieces (T7) are linked to the movable rod through the connecting rod (T11). When the movable rod is pushed inward toward the transformer, the spring pieces (T7) are closed to allow the penetrator to pass through the transition plate (T6). When the movable rod is pulled outward toward the transformer, the movable rod moves in the direction of the transformer's outward, and the connecting rod (T11) drives the spring pieces (T7) to open and press tightly against the inner wall of the transformer to achieve a compression seal.

3. The optical microphone vibration environment reliability testing device as described in claim 1, characterized in that: The oil immersion environment simulation system also includes an oil pump, which is connected to the inlet and outlet and is used to fill and discharge transformer oil into the test chamber.

4. The optical microphone vibration environment reliability testing device as described in claim 1, characterized in that: The vibration simulation system has a vibration frequency adjustment range of 1Hz to 600Hz, with a frequency adjustment accuracy of not less than 0.1Hz; a vibration amplitude range of 0 to 5mm; and an acceleration range of 0 to 20g.

5. The optical microphone vibration environment reliability testing device as described in claim 1, characterized in that: The vibration simulation system supports independent or mixed vibrations in the X, Y, and Z axes of the test chamber (1).

6. The optical microphone vibration environment reliability testing device as described in claim 1, characterized in that: The penetrator (10) is located on the side of the test chamber (1).

7. The optical microphone vibration environment reliability testing device as described in claim 6, characterized in that: The test chamber (1) is also provided with an observation window (5) on its side.

8. A method for testing the vibration environment reliability of an optical microphone based on the device described in any one of claims 1-7, characterized in that, Includes at least one of the following tests: Acoustic performance testing under vibration environment, interference cavity stability testing, reflective diaphragm durability testing, and fiber optic bending loss testing under vibration conditions; The acoustic performance test under vibration environment includes the following steps: The optical microphone (6) to be tested is fixed inside the test cavity; Transformer oil is injected into the test chamber through the oil immersion environment simulation system. The lowest liquid level of the transformer oil injected into the test chamber during vibration is higher than the highest point of the optical microphone (6). Ultrasonic signals are generated by the ultrasonic signal generating system. The vibration simulation system is controlled to vibrate at a preset vibration frequency, amplitude, and acceleration; The signal-to-noise ratio and sensitivity of the optical microphone (6) were measured under different vibration parameters; The signal-to-noise ratio and sensitivity of the optical microphone (6) are analyzed as a function of vibration parameters; The vibration parameters include vibration frequency, amplitude, acceleration, and vibration direction; The stability test of the interference cavity includes the following steps: The optical microphone (6) to be tested is fixed inside the test cavity; Transformer oil is injected into the test chamber through the oil immersion environment simulation system. The lowest liquid level of the transformer oil injected into the test chamber during vibration is higher than the highest point of the optical microphone (6). Before the vibration begins, the initial cavity length of the Fabry-Perot interferometer cavity of the optical microphone (6) is measured using a laser interferometer; The vibration simulation system is started, and the cavity length change of the optical microphone (6) is measured at different vibration frequencies. The drift of the interference spectrum is recorded using a spectrometer. A mapping model between cavity length offset and vibration frequency was established to analyze the variation of cavity length with vibration frequency. The durability test of the reflective film includes the following steps: The optical microphone (6) to be tested is fixed inside the test cavity; Transformer oil is injected into the test chamber through the oil immersion environment simulation system. The lowest liquid level of the transformer oil injected into the test chamber during vibration is higher than the highest point of the optical microphone (6). Start the vibration simulation system to perform continuous vibration; At predetermined time intervals, the surface morphology of the reflective film of the optical microphone (6) is observed using a microscope, and the peeling area is calculated; at the same time, the reflectivity of the reflective film of the optical microphone (6) is measured using a spectrophotometer, and the reflectivity attenuation rate is calculated. Analyze the variation of the peeling area and reflectivity attenuation rate with vibration time; The fiber bending loss test under vibration conditions includes the following steps: A section of fiber optic patch cord simulating the actual deployment state is bent and fixed inside the test cavity; Connect the laser source to the input end of the fiber optic patch cord, and connect the optical power meter to the output end of the fiber optic patch cord; Transformer oil is injected into the test chamber through the oil immersion environment simulation system. The lowest liquid level of the transformer oil injected into the test chamber during vibration is higher than the highest point of the optical microphone (6). The vibration simulation system is controlled to perform frequency sweep vibration; Record the optical power under static conditions And the dynamic optical power P(f) at different vibration frequencies f; Calculate the frequency attenuation rate and frequency attenuation coefficient of optical power, analyze the law of optical power attenuation with vibration frequency, and locate the critical failure frequency.

9. The method for testing the reliability of an optical microphone in a vibration environment as described in claim 8, characterized in that: When the vibration simulation system supports independent or mixed vibrations in the X, Y, and Z axes of the test chamber (1), the vibration environment reliability test method of the optical microphone (6) includes multi-axial vibration influence test; The multiaxial vibration effect test includes the following steps: Multiple optical microphones (6) to be tested are fixed inside the test cavity; Transformer oil is injected into the test chamber through the oil immersion environment simulation system. The lowest liquid level of the transformer oil injected into the test chamber during vibration is higher than the highest point of the optical microphone (6). Ultrasonic signals are generated by the ultrasonic signal generating system. The vibration simulation system is controlled to apply vibrations in the X, Y, and Z axes respectively, and the signal-to-noise ratio and sensitivity of the optical microphone (6) under different vibration directions are tested and recorded respectively; and / or the vibration simulation system is controlled to apply vibrations in the X, Y, and Z axes simultaneously, and the signal-to-noise ratio and sensitivity of the optical microphone (6) are tested and recorded. The effect of vibration direction on the detection performance of the optical microphone (6) was evaluated.

10. The method for testing the reliability of an optical microphone in a vibration environment as described in claim 8, characterized in that: When testing acoustic performance or interference cavity stability under vibration, the vibration frequency starts from 1 Hz and gradually increases to 600 Hz in 50 Hz increments.

11. The method for testing the reliability of an optical microphone in a vibration environment as described in claim 8, characterized in that: Including interference cavity stability test, reflective diaphragm durability test and fiber bending loss test under vibration, the lifetime prediction and / or reliability analysis of the optical microphone (6) are carried out by combining the results of the interference cavity stability test, reflective diaphragm durability test and fiber bending loss test under vibration.

Images