Transformer noise active suppression cover based on acoustic metamaterial and use method thereof

Abstract

The invention relates to an active transformer noise suppression cover based on acoustic metamaterials and a use method of the active transformer noise suppression cover, and belongs to the technical field of power equipment noise control. The active transformer noise suppression cover comprises a cover body, a plurality of acoustic metamaterial units, a ventilation and heat dissipation module, a cable leading-out module, an active noise reduction system and a damping base; the modules are laid in the cover body; the acoustic metamaterial unit comprises a unit body, the unit body is composed of a rigid framework and a sound absorption material filled in the framework, and at least one resonant cavity is completely embedded in the unit body. According to the invention, the noise reduction effect is remarkable, the frequency band coverage is wide, the acoustic metamaterial unit is used for targeted absorption and isolation of 100-500Hz low-frequency noise, and the active noise reduction system is used for dynamically and accurately counteracting residual noise of the frequency band, so that complementation of passive and active noise reduction technologies in frequency band and efficiency is realized, and the overall noise reduction effect is far better than that of a single technical scheme.

Description

Technical Field

[0001] This invention relates to the field of power equipment noise control technology, and in particular to an active noise suppression cover for transformers based on acoustic metamaterials and its application method. Background Technology

[0002] Transformers generate significant low-frequency noise during operation, mainly from the vibration caused by the magnetostriction of the iron core and the electromagnetic force vibration of the windings. The main energy is concentrated in the range of 100-500Hz. There are a large number of distribution transformers in cities, and they are often installed near residential areas. The low-frequency noise they generate can travel a long distance and easily cause noise pollution problems.

[0003] Currently, noise reduction measures for transformers mainly employ traditional soundproof enclosures or sound barriers, but these measures have the following limitations:

[0004] 1. Poor low-frequency noise reduction effect: Traditional sound insulation materials and structures follow the mass law and have limited sound insulation effect on low-frequency noise of 100-500Hz, resulting in bulky structures. For example, the acoustic metamaterial barrier design method for transformer noise reduction in patent publication number CN201811002648.7 can target specific frequencies, but lacks the ability to dynamically adjust to complex noise spectrum.

[0005] 2. The contradiction between heat dissipation and noise reduction: Existing noise reduction covers often sacrifice ventilation and ignore heat dissipation requirements in pursuit of noise reduction effect. The inertial amplification acoustic metamaterial structure and substation noise protection device with patent publication number CN117079626A has a good passive noise reduction effect, but the problem of integrating heat dissipation and noise reduction has not been solved.

[0006] 3. Limited technology and insufficient adaptability: Existing technologies mostly adopt a single passive noise reduction or a single active noise reduction scheme. For example, a transformer noise suppression method with patent publication number CN103971908B uses active control technology based on BP neural network algorithm. If it is not combined with efficient passive sound insulation, its noise reduction effect and stability in high sound pressure level environments will be limited.

[0007] 4. Lack of vibration control: Existing technologies rarely consider the structural noise problem caused by transformer vibration propagating through the foundation.

[0008] Therefore, there is an urgent need for a comprehensive solution that integrates efficient passive sound insulation, dynamic active control, efficient heat dissipation, and vibration isolation. By combining passive and active noise reduction technologies using acoustic metamaterials, this solution can effectively suppress the low-frequency noise characteristics of transformers, thus solving the technical problems of poor low-frequency noise performance and reduced heat dissipation of transformers caused by traditional sound insulation devices. Summary of the Invention

[0009] This invention provides an active noise suppression cover for transformers based on acoustic metamaterials and its usage method, which solves the technical problems of poor low-frequency noise suppression, prominent contradiction between heat dissipation and noise reduction, and lack of coordinated control of vibration and noise in existing transformer noise reduction equipment.

[0010] The present invention provides the following solution to the above-mentioned technical problems: an active noise suppression cover for transformers based on acoustic metamaterials, comprising a cover body, acoustic metamaterial units, ventilation and heat dissipation modules, cable lead-out modules, an active noise reduction system, and a vibration damping base. Multiple acoustic metamaterial units are provided and modularly laid inside the cover body.

[0011] The acoustic metamaterial unit includes a unit body, which is composed of a rigid skeleton and sound-absorbing material filled in the skeleton. At least one resonant cavity is completely embedded inside the unit body. The resonant cavity is a spiral channel structure or a Helmholtz resonator structure. The wall of the resonant cavity is made of rigid material. Its structural parameters are configured to make the resonant frequency match the 100-500Hz main frequency range of transformer noise.

[0012] The enclosure has an internal space that conforms to the shape of the transformer and is equipped with a temperature sensor.

[0013] Both the ventilation and heat dissipation module and the cable lead-out module are located in the cover;

[0014] The active noise cancellation system includes an error microphone, a reference microphone, a controller, and a secondary sound source. The reference microphone is located inside the enclosure near the transformer core, while the error microphone is positioned 1-2 meters outside the enclosure along the main noise propagation path. The secondary sound source is located on the inner side wall of the enclosure. The controller employs a filtered x-LMS algorithm. The internal reference microphone can collect the original noise that has not been attenuated by the passive noise cancellation enclosure, providing advance for the system. The external error microphone directly monitors the final noise reduction effect and feeds back the residual noise to the controller. The filtered x-LMS algorithm can dynamically adjust the anti-phase sound waves emitted by the secondary sound source, tracking and canceling noise changes in real time.

[0015] The shock-absorbing base includes a fixed base plate, a fixed plate, and a shock-absorbing layer, wherein the shock-absorbing layer is disposed between the fixed base plate and the fixed plate.

[0016] Based on the above technical solution, the present invention can be further improved as follows.

[0017] Furthermore, the total length L of the spiral channel structure of the resonant cavity is designed according to the target resonant frequency f using the formula f = c / (4L), where c is the speed of sound and L ranges from 0.2 to 1.5 meters. The given length range clearly covers the physical dimensions required for the 100-500Hz noise frequency band of the transformer, overcoming the blindness and inefficiency of traditional sound insulation materials in low-frequency design.

[0018] Furthermore, the Helmholtz resonator structure of the resonant cavity consists of a neck cavity and a main body cavity. Its resonant frequency f is determined by the formula f=(c / 2π)√(S / (VL')), where S is the cross-sectional area of ​​the neck, V is the volume of the main body cavity, and L' is the effective length of the neck. By flexibly adjusting the two independent geometric parameters of the neck size and the cavity volume, the required resonant frequency can be precisely customized without changing the overall shape of the unit. This is particularly suitable for complex noise environments that require targeting multiple discrete low-frequency peaks.

[0019] Furthermore, the acoustic metamaterial unit is a regular hexagonal prism structure, which is assembled by snaps and sealing strips on the edge of the unit. This structural design realizes the modularity of the enclosure and rapid on-site installation. The regular hexagonal structure can achieve seamless and close-fitting installation, effectively avoiding sound leakage channels caused by seam alignment and ensuring the acoustic integrity of the overall enclosure.

[0020] Furthermore, the matrix material of the acoustic metamaterial unit is aluminum silicate fiberboard.

[0021] Furthermore, the ventilation and heat dissipation module includes an air intake pipe, an exhaust pipe, a fan, and a water-cooled circulation pipe. Both the air intake and exhaust pipes are equipped with micro-perforated plate silencers. The fan is connected to the air intake pipe. The water-cooled circulation pipe is located within the transformer and is connected to a circulation pump and a cooling system, forming a water-cooled heat dissipation system. This resolves the inherent contradiction between noise reduction and heat dissipation. The micro-perforated plate silencer is a highly efficient reactive silencer that effectively attenuates airflow noise, especially low-to-mid-frequency noise, passing through the pipe. This ensures ventilation and heat dissipation without becoming a new noise leakage point. Combining air cooling and water cooling forms a composite heat dissipation system. The water-cooled circulation pipe efficiently removes heat from the core area inside the enclosure, while the air cooling system is responsible for overall ventilation and auxiliary heat dissipation, ensuring the long-term safe and stable operation of the transformer in a sealed, soundproof environment.

[0022] Furthermore, the damping layer of the damping base is made of high-damping rubber material with a thickness of 40-60mm. Four to six passive air spring vibration dampers are installed on the upper side of the fixing plate, achieving source control of transformer vibration noise from the propagation path. The high-damping rubber layer effectively isolates and dissipates high-frequency vibration energy, while the low-natural-frequency air spring vibration dampers are specifically designed to isolate the transformer's strong low-frequency magnetostrictive vibration.

[0023] A method for using an active noise suppression cover for transformers includes the following steps:

[0024] S1. Place the transformer on the vibration-damping base and secure it with bolts;

[0025] S2. Assemble the prefabricated acoustic metamaterial enclosure modules around the transformer, ensuring the interfaces are sealed;

[0026] S3. Connect the transformer input and output cables through the labyrinthine conduit of the cable lead-out module;

[0027] S4. Start the active noise cancellation system, collect noise signal x(n) through the reference microphone, generate an anti-phase sound wave y(n) according to the filtering x-LMS algorithm of the controller, emit it through the secondary sound source, and detect residual noise e(n) through the error microphone and feed it back to the controller for adaptive adjustment;

[0028] S5. When the temperature inside the enclosure exceeds the set threshold, the fan in the ventilation and heat dissipation module is activated for forced cooling.

[0029] The beneficial effects of this invention are as follows: This invention provides an active noise suppression cover for transformers based on acoustic metamaterials and its usage method, which has the following advantages:

[0030] 1. Significant noise reduction effect and wide frequency band coverage. Through the targeted absorption and isolation of low-frequency noise in the 100-500Hz range by acoustic metamaterial units, combined with the dynamic and precise cancellation of residual noise in this frequency band by the active noise reduction system, the passive and active noise reduction technologies complement each other in terms of frequency band and efficiency. The overall noise reduction effect far exceeds that of a single technical solution.

[0031] 2. The system has a high degree of integration and strong synergistic effect. Through the coordinated design of four major modules—acoustic metamaterials, active noise reduction, ventilation and heat dissipation, and vibration damping base—in acoustics, structure, and control, a comprehensive solution of "passive sound insulation + active noise cancellation + efficient heat dissipation + vibration isolation" has been formed, resulting in better synergistic governance effect.

[0032] 3. Reliable heat dissipation performance ensures equipment safety. It adopts a composite heat dissipation mode of "air cooling + water cooling" and innovatively integrates micro-perforated plate silencers in the ventilation ducts, ensuring that heat dissipation efficiency and sound insulation performance are not mutually exclusive. This provides a solid guarantee for the long-term safe and stable operation of the transformer in the sealed enclosure. The modular acoustic metamaterial enclosure, the ventilation duct with built-in micro-perforated plate silencers, and the water cooling circulation system solve the inherent contradiction between sealed sound insulation and internal equipment heat dissipation from the structural design, achieving the parallel function of noise reduction and heat dissipation.

[0033] 4. Strong environmental adaptability and easy engineering implementation: The modular acoustic metamaterial enclosure design facilitates transportation and rapid on-site assembly, making it suitable for deployment in complex environments with limited space, such as urban residential areas. At the same time, the active noise reduction system has adaptive adjustment capabilities, which can cope with noise fluctuations caused by changes in transformer load, ensuring stable long-term operation. The vibration damping base isolates the transformer's own vibration from the vibration propagation path, and together with the acoustic enclosure, it forms an integrated "vibration-noise" control strategy, reducing the risk of structural sound transmission from the source.

[0034] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it according to the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Specific embodiments of the present invention are given in detail below with reference to the accompanying drawings. Attached Figure Description

[0035] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings:

[0036] Figure 1 This is a schematic diagram of the structure of an active noise suppression cover for a transformer based on acoustic metamaterials and its usage method, provided in an embodiment of the present invention.

[0037] Figure 2 A front view of an active noise suppression cover for a transformer based on acoustic metamaterials and its usage method provided in an embodiment of the present invention;

[0038] Figure 3 This is a schematic diagram of the structure of a transformer noise active suppression cover based on acoustic metamaterials and its usage method provided in an embodiment of the present invention.

[0039] The attached diagram lists the components represented by each number as follows:

[0040] 1. Enclosure; 2. Acoustic metamaterial unit; 201. Unit body; 202. Resonance cavity; 3. Ventilation and heat dissipation module; 301. Inlet pipe; 302. Exhaust pipe; 303. Fan; 304. Water-cooled circulation pipe; 305. Micro-perforated plate silencer; 4. Cable lead-out module; 5. Active noise reduction system; 501. Error microphone; 502. Reference microphone; 503. Controller; 504. Secondary sound source; 6. Vibration damping base; 601. Fixed base plate; 602. Fixed plate; 603. Vibration damping layer. Detailed Implementation

[0041] The following is in conjunction with the appendix Figure 1-3 The principles and features of the present invention are described below. The examples given are for illustrative purposes only and are not intended to limit the scope of the invention. The invention is described more specifically in the following paragraphs by way of example with reference to the accompanying drawings. The advantages and features of the invention will become clearer from the following description. It should be noted that the drawings are in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the invention.

[0042] It should be noted that when a component is described as "fixed to" another component, it can be directly on the other component or may have a component in between. When a component is considered "connected to" another component, it can be directly connected to the other component or may have a component in between. When a component is considered "set on" another component, it can be directly set on the other component or may have a component in between. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0044] like Figure 1-3 As shown, the present invention provides a transformer noise active suppression cover based on acoustic metamaterials and its usage method, including cover body 1, acoustic metamaterial unit 2, ventilation and heat dissipation module 3, cable lead-out module 4, active noise reduction system 5 and vibration damping base 6;

[0045] The enclosure 1 is assembled with multiple modular acoustic metamaterial units 2, forming a closed space that completely encloses the transformer;

[0046] The acoustic metamaterial unit 2 adopts a regular hexagonal prism structure with an outer circle diameter of 200mm and a height of 100mm. This shape can achieve seamless tiling and effectively avoid sound leakage.

[0047] Matrix material: Unit body 201 uses a density of 110 kg / m³ 3 The aluminum silicate fiberboard combines good sound absorption and structural strength, and the resonant cavity has two designs.

[0048] Implementation method A (spiral channel structure): In response to the prominent 100Hz noise of the transformer, according to the formula f=c / (4L) (where c is taken as 340m / s), the total length of the spiral channel is designed to be L=0.85m. The channel has a square cross section (10mm×10mm) and is integrally formed in the aluminum silicate fiberboard matrix through a molding process.

[0049] Implementation Method B (Helmholtz Resonator Structure): For 200Hz noise, a Helmholtz resonator is designed, with its main cavity being a sphere with a diameter of 60mm (volume V≈113,000mm³), and its neck being a sphere with a diameter of 10mm (cross-sectional area S≈78.5mm²). 2 The effective length L' of the 15mm physical length circular tube is calculated according to the formula L'≈L+0.48*√S. The resonant frequency is verified by the formula f=(c / 2π)*√(S / (V*L')) and confirmed to be 200Hz. The neck part is manufactured by 3D printing and embedded in the matrix with a cavity reserved during molding.

[0050] Assembly method: Each unit is prefabricated in the factory and mechanically connected on site through metal clips embedded in the edge of the unit. Closed-cell rubber sealing strips are filled at all joints to ensure the overall acoustic sealing of the enclosure 1.

[0051] The active noise cancellation system 5 is used to dynamically cancel noise that the acoustic metamaterials cannot completely eliminate, and the hardware layout is as follows;

[0052] Reference microphone 502: Two GRAS46AE type microphones are selected and installed on the inner wall of housing 1, facing the transformer core, to collect the original noise signal x(n);

[0053] Error microphone 501: Four GRAS46AE microphones of the same model are selected and installed 1.5 meters outside the enclosure 1 in the main noise propagation direction (such as the side facing the residential building) to monitor the residual noise e(n) after noise reduction.

[0054] Secondary sound source 504: Four Beyma12P80ND coaxial loudspeakers are selected and evenly distributed on the inner side wall of the enclosure 1.

[0055] Controller 503: The core uses the National Instruments CRIO-9045 embedded real-time controller, paired with the NI9234 analog input module and the NI9263 analog output module;

[0056] The controller 503 runs an adaptive control program based on the x-LMS filtering algorithm. After the system is powered on, it first performs offline identification of the secondary path (the transfer function from the secondary sound source 504 to the error microphone 501). During normal operation, the controller calculates and updates the filter coefficients W(n) in real time based on the reference signal x(n) and the error signal e(n), and generates an antiphase sound wave y(n) to drive the secondary sound source 504. The convergence step size μ is set to 0.0005 to achieve stable and fast convergence.

[0057] Ventilation and heat dissipation module 3 is used to solve the heat dissipation problem of the transformer inside the sealed enclosure;

[0058] Air-cooled system: An air inlet pipe 301 and an exhaust pipe 302 are respectively installed on both sides of the cover 1. The pipes are made of galvanized steel plate with a diameter of 250mm. A micro-perforated plate silencer 305 is installed inside the pipe. The silencer is made of 1mm thick aluminum alloy plate with a hole diameter of 0.5mm, a hole spacing of 10mm, and a perforation rate of 2.5%, which can effectively attenuate airflow noise. An EBM-papst615-208 axial flow fan 303 is installed in the air inlet pipe 301.

[0059] Water cooling system: UPVC pipes are bent into 304 water cooling circulation pipes and tightly wrapped around the transformer heat sink. The circulation pipes are connected to a circulation pump and a chiller to form a closed water cooling circulation.

[0060] Control system: A PT100 temperature sensor is installed inside the enclosure 1 near the high-voltage side of the transformer. When the temperature inside the enclosure exceeds the set threshold of 50°C, the control system first starts the water-cooled circulation pump. If the temperature continues to be higher than 55°C, the axial flow fan 303 is further started for forced air cooling.

[0061] The shock-absorbing base 6 is used to isolate the transformer body vibration;

[0062] The structure, from bottom to top, includes:

[0063] Fixed base plate 601: 20mm thick Q235 steel plate, fixed to the concrete foundation with anchor bolts;

[0064] Damping layer 603: a 50mm thick high-damping rubber sheet with a Shore hardness of 50;

[0065] Fixing plate 602: 20mm thick Q235 steel plate, used to support the transformer;

[0066] Vibration dampers: On the upper surface of the fixed plate 602, corresponding to the four mounting feet of the transformer, a Vibrasorb International AV-45 passive air spring vibration damper is installed at each position. Its natural frequency is 4Hz, which can effectively isolate the low-frequency vibration generated by the magnetostriction of the transformer core.

[0067] The cable lead-out module 4 is a labyrinthine conduit structure installed on the side wall of the enclosure 1. The inside is filled with ceramic silicone rubber fireproof putty to ensure that the cable passes through while maintaining good acoustic sealing and fireproof performance.

[0068] The specific working principle and usage method of this invention are as follows:

[0069] S1. Hoist the transformer onto the vibration damping base 6 and fasten it to the air spring vibration damper with bolts. Then, assemble the prefabricated acoustic metamaterial unit 2 around the transformer to form a complete cover 1. Finally, lead out and connect the transformer input and output cables through the labyrinth-type conduit of the cable lead-out module 4.

[0070] S2. Debugging: Power on the active noise cancellation system 5, run the control software through the connected industrial control computer to perform secondary path identification, then start the adaptive algorithm, observe the signal of the error microphone 501, and fine-tune the convergence step size to make the system reach the best noise reduction state.

[0071] S3. Operation: After the transformer is put into operation, the active noise reduction system 5 continues to work to dynamically cancel noise, and the temperature monitoring system automatically manages the start and stop of the ventilation and heat dissipation module 3 to ensure that the transformer temperature rise is within a safe range.

[0072] S4. Maintenance: Clean the dust filter of intake pipe 301 regularly (e.g., monthly), check the chiller and water cooling pipeline every quarter, and calibrate the microphone sensitivity every six months.

[0073] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Content not described in detail in this specification is prior art known to those skilled in the art.

[0074] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Those skilled in the art can readily implement the present invention based on the accompanying drawings and the above description. However, any modifications, alterations, or variations made by those skilled in the art without departing from the scope of the present invention, utilizing the disclosed technical content, are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, or variations made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the present invention.

Claims

1. A transformer noise active suppression cover based on acoustic metamaterials, comprising a cover body (1), an acoustic metamaterial unit (2), a ventilation and heat dissipation module (3), a cable lead-out module (4), an active noise reduction system (5), and a vibration damping base (6), characterized in that: Multiple acoustic metamaterial units (2) are provided and modularly laid inside the cover (1); The acoustic metamaterial unit (2) includes a unit body (201), which is composed of a rigid frame and a sound-absorbing material filled in the frame. The interior of the unit body (201) is completely embedded with at least one resonant cavity (202). The resonant cavity (202) is a spiral channel structure or a Helmholtz resonator structure. The wall of the resonant cavity (202) is made of rigid material, and its structural parameters are configured to make the resonant frequency match the 100-500Hz main frequency range of transformer noise. The enclosure (1) has an internal space that conforms to the shape of the transformer and is equipped with a temperature sensor. The ventilation and heat dissipation module (3) and the cable lead-out module (4) are both installed in the cover (1); The active noise cancellation system (5) includes an error microphone (501), a reference microphone (502), a controller (503), and a secondary sound source (504). The reference microphone (502) of the active noise cancellation system (5) is located inside the enclosure (1) near the transformer core. The error microphone (501) is located 1-2 meters outside the enclosure (1) on the main noise propagation path. The secondary sound source (504) is located on the inner side wall of the enclosure (1). The controller (503) uses the x-LMS filtering algorithm. The shock-absorbing base (6) includes a fixed base plate (601), a fixed plate (602), and a shock-absorbing layer (603), wherein the shock-absorbing layer (603) is disposed between the fixed base plate (601) and the fixed plate (602).

2. The transformer noise active suppression cover based on acoustic metamaterials according to claim 1, characterized in that, The total length L of the spiral channel structure of the resonant cavity (202) is designed according to the target resonant frequency f using the formula f = c / (4L), where c is the speed of sound and L ranges from 0.2 to 1.5 meters.

3. The transformer noise active suppression cover based on acoustic metamaterials according to claim 1, characterized in that, The Helmholtz resonator structure of the resonant cavity (202) consists of a neck cavity and a main cavity. Its resonant frequency f is determined by the formula f=(c / 2π)√(S / (VL')), where S is the cross-sectional area of ​​the neck, V is the volume of the main cavity, and L' is the effective length of the neck.

4. The transformer noise active suppression cover based on acoustic metamaterials according to claim 1, characterized in that, The acoustic metamaterial unit (2) is a regular hexagonal prism structure, which is assembled by snap-fit ​​and sealing strips on the edge of the unit.

5. The transformer noise active suppression cover based on acoustic metamaterials according to claim 1, characterized in that, The matrix material of the acoustic metamaterial unit (2) is aluminum silicate fiberboard.

6. The transformer noise active suppression cover based on acoustic metamaterials according to claim 1, characterized in that, The ventilation and heat dissipation module (3) includes an air inlet pipe (301), an exhaust pipe (302), a fan (303), and a water-cooled circulation pipe (304). The air inlet pipe (301) and the exhaust pipe (302) are both equipped with micro-perforated plate silencers (305). The fan (303) is connected to the air inlet pipe (301). The water-cooled circulation pipe (304) is located on the transformer and is connected to a circulation pump and a chiller to form a water-cooled heat dissipation system.

7. The transformer noise active suppression cover based on acoustic metamaterials according to claim 1, characterized in that, The damping layer (603) of the damping base (6) is made of high-damping rubber material with a thickness of 40-60mm, and 4-6 passive air spring dampers are provided on the upper side of the fixing plate (602).

8. A method of using a transformer noise active suppression cover based on acoustic metamaterials as described in any one of claims 1-7, characterized in that, Includes the following steps: S1. Place the transformer on the shock-absorbing base (6) and fix it with bolts; S2. Assemble the prefabricated acoustic metamaterial enclosure modules around the transformer, ensuring the interfaces are sealed; S3. Connect the transformer input and output cables through the labyrinthine conduit of the cable lead-out module (4); S4. Start the active noise reduction system (5), collect noise signal x(n) through reference microphone (502), and the controller (503) generates antiphase sound wave y(n) according to the filtering x-LMS algorithm. It is emitted through secondary sound source (504), and the error microphone (501) detects residual noise e(n) and feeds it back to the controller (503) for adaptive adjustment. S5. When the temperature inside the cover exceeds the set threshold, start the fan (303) in the ventilation and heat dissipation module (3) for forced cooling.

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