Composite sound absorbing muffler

Abstract

A composite sound-absorbing silencer includes: a low-frequency sound-absorbing module and a mid-to-high-frequency sound-absorbing module installed inside the ventilation opening of a substation; the low-frequency sound-absorbing module adopts an internal tube superstructure design to absorb noise in the first frequency band radiated from the transformer body; the mid-to-high-frequency sound-absorbing module absorbs noise in the second frequency band radiated from the transformer body through frictional loss; the frequency of the first frequency band noise is lower than the frequency of the second frequency band noise. This invention can adjust the usable area and arrangement of the internal modular low-frequency sound-absorbing modules according to the actual cross-sectional area of ​​the ventilation opening and the environmental ventilation requirements, thereby controlling the radiated noise from the transformer in the indoor substation; the product has the lowest pressure loss along the entire airflow path, improving the cooling safety and reliability of the equipment operation; and by installing a wire mesh at the silencer's air inlet, it strengthens the protection against external objects and extends the service life of the equipment.

Description

Technical Field

[0001] This invention relates to the field of noise control, and more specifically to a composite sound-absorbing silencer. Background Technology

[0002] With the improvement of people's living standards, the demand for electricity is increasing. Many urban substations are built near residential areas, and the noise from these substations inevitably affects people's lives and work. To meet environmental protection requirements for substation / converter station boundary noise, noise reduction of the ventilation openings in indoor substations has become a relatively effective method. Since ventilation openings are a weak point in noise reduction, the radiated noise directly affects the overall noise level of the indoor substation. Given the requirements for equipment ventilation and cooling, noise reduction of the ventilation openings must not compromise these requirements.

[0003] Noise can be divided into high-frequency noise and low-frequency noise. Outdoors, high-frequency noise attenuates rapidly with increasing distance or when blocked by obstacles; while low-frequency noise has longer sound waves and can travel long distances through obstacles, attenuating very slowly with increasing distance. However, current research often overlooks the fact that indoors, due to the relatively small indoor area, high-frequency noise attenuates slowly, and its impact on users is equally significant. To address the aforementioned issues, Chinese patent CN106192785A provides a full-band noise reduction barrier and shielding device for substations. It employs a metamaterial low-frequency noise reduction layer and a high-frequency noise reduction layer. The metamaterial low-frequency noise reduction layer is positioned at the front end of the full-band noise reduction barrier body, while the high-frequency noise reduction layer is positioned at the rear end. The metamaterial low-frequency noise reduction layer consists of several periodically arranged lattices, with a silicone rubber elastic film placed between each lattice. A mass block is attached to one side of the silicone rubber elastic film in the direction of sound incidence. Although this invention provides a full-band noise reduction barrier with good noise reduction capabilities across high, medium, and low frequencies, the use of multiple materials and a multi-layered structure significantly increases production costs. Furthermore, consideration of wind resistance, corrosion resistance, and insulation properties limits its use in specific environments.

[0004] Therefore, how to solve the problems of incomplete noise reduction and high cost in existing technologies for indoor substations is an urgent issue to be addressed in the field of noise control. Summary of the Invention

[0005] To address the problems of incomplete noise reduction and high cost in existing technologies for indoor substations, this invention provides a composite sound-absorbing silencer, comprising: a low-frequency sound-absorbing module and a medium-to-high-frequency sound-absorbing module disposed within the ventilation opening of the substation.

[0006] The low-frequency sound-absorbing module adopts an internal tube superstructure design to absorb the first frequency band noise radiated from the transformer body.

[0007] The mid-to-high frequency sound-absorbing module absorbs noise from the second frequency band radiated by the transformer body through frictional loss.

[0008] The frequency of the noise in the first frequency band is lower than the frequency of the noise in the second frequency band.

[0009] Preferably, there are multiple low-frequency sound-absorbing modules and multiple mid-to-high-frequency sound-absorbing modules.

[0010] Preferably, the multiple low-frequency sound-absorbing modules and the multiple medium- and high-frequency sound-absorbing modules are fixed inside the substation ventilation opening in a cross-shaped or spaced arrangement.

[0011] Preferably, the low-frequency sound-absorbing module includes: a housing and a tube, wherein the housing has at least one through hole for inserting the tube on the side facing the sound source.

[0012] Preferably, each surface of the box is made of galvanized sheet.

[0013] Preferably, the insertion tube has an opening at one end outside the box, and a small hole is provided on the side wall or bottom of the insertion tube inside the box.

[0014] Preferably, the length of the cannula is 3.4 mm to 77.4 mm.

[0015] Preferably, the small hole is a rectangular small hole or a circular small hole.

[0016] Preferably, the mid-to-high frequency sound-absorbing module includes: a shell composed of plates and its internal filling material, wherein the plates include porous sound-absorbing panels.

[0017] Preferably, the pore size of the porous sound-absorbing panel is 0.1mm to 1mm.

[0018] Preferably, the perforation rate of the porous sound-absorbing panel is 0.1% to 30%.

[0019] Preferably, the plate comprises a galvanized plate.

[0020] Preferably, the filling material is selected from at least one of rock wool and glass fiber wool.

[0021] Preferably, when the plurality of low-frequency sound-absorbing modules and the plurality of mid-to-high-frequency sound-absorbing modules are arranged in a cross-shaped configuration on a single plane, the plurality of low-frequency sound-absorbing modules are arranged in a cross-shaped configuration on a single plane.

[0022] Multiple mid-to-high frequency sound-absorbing modules are evenly filled between the outer and inner walls of the cross, and are located on the same plane as the low-frequency sound-absorbing modules.

[0023] Preferably, the multiple low-frequency sound-absorbing modules and the multiple mid-to-high-frequency sound-absorbing modules are arranged in an interleaved configuration, which can be either an embedded type or a split type.

[0024] Preferably, when the plurality of low-frequency sound-absorbing modules and the plurality of mid-to-high-frequency sound-absorbing modules are configured in the embedded manner, the low-frequency sound-absorbing modules are embedded in the filling material of the mid-to-high-frequency sound-absorbing modules.

[0025] Preferably, when the multiple low-frequency sound-absorbing modules and the multiple mid-to-high-frequency sound-absorbing modules are configured in the shunt configuration, the low-frequency sound-absorbing modules are located at the end of the substation ventilation opening closest to the sound source, and the multiple low-frequency sound-absorbing modules are arranged closely together laterally to form a low-frequency sound-absorbing layer.

[0026] The mid-to-high frequency sound-absorbing module is arranged horizontally adjacent to the low-frequency sound-absorbing layer and is located at the end furthest from the sound source, forming a composite sound-absorbing layer.

[0027] The single sound-absorbing layer composed of the mid-to-high frequency sound-absorbing module is arranged longitudinally parallel to the mid-to-high frequency sound-absorbing module of the composite sound-absorbing layer.

[0028] The composite sound-absorbing layer is installed at both ends of the ventilation opening of the substation;

[0029] The substation ventilation opening has at least one low-frequency sound-absorbing layer in the middle.

[0030] As described in any of the above-mentioned composite sound-absorbing silencers, the first frequency band noise includes single-frequency noise of 100-500Hz; the second frequency band noise includes mid-to-high frequency noise of 500-2000Hz.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] This invention provides a composite sound-absorbing silencer, comprising: a low-frequency sound-absorbing module and a mid-to-high-frequency sound-absorbing module; the low-frequency sound-absorbing module is placed on the side wall and / or in the gaps of the outer enclosure ventilation duct; the mid-to-high-frequency sound-absorbing module is placed on the side wall and / or in the gaps of the outer enclosure ventilation duct. By combining the low-frequency and mid-to-high-frequency sound-absorbing modules, effective control of both low-frequency and mid-to-high-frequency noise can be achieved simultaneously. Cost-effective aluminum alloy sheet metal enclosure ventilation duct and galvanized steel are selected as the main materials. These materials not only have good sound absorption performance but also corrosion resistance and strength, thereby reducing material costs and extending the product's service life. This invention provides two design methods for the low-frequency and high-frequency sound-absorbing modules to meet different needs.

[0033] This invention allows for adjustment of the usable area and layout of the internal modular low-frequency sound-absorbing modules based on the actual cross-sectional area of ​​the ventilation openings and environmental ventilation requirements, thereby controlling the radiated noise from transformers in indoor substations. The product incorporates modular porous material sound-absorbing panels; by adjusting the panel spacing and dimensions, mid-to-high frequency noise can be controlled, and physical dimensions can be adjusted according to different size requirements for rapid response and integration. The product exhibits minimal pressure loss throughout the airflow path, improving the cooling safety and reliability of equipment operation. By installing a wire mesh at the silencer's air inlet, protection against external objects is enhanced, extending the equipment's service life. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the overall external structure of the low-frequency sound-absorbing module of the present invention;

[0035] Figure 2 This is a schematic diagram of the low-frequency sound-absorbing module of the present invention;

[0036] Figure 3 This is a partial cross-sectional view of the low-frequency resonant sound-absorbing structure of the present invention;

[0037] Figure 4 This is a schematic diagram of the overall structure of the cross-shaped muffler of the present invention;

[0038] Figure 5 In this invention Figure 4 Plan view in direction B;

[0039] Figure 6 In this invention Figure 4 Plan view in the C direction;

[0040] Figure 7 This is a schematic diagram of the embedded structure of the silencer arranged at intervals according to the present invention;

[0041] Figure 8 This is a schematic diagram of the embedded sound wave propagation in the silencer arranged at intervals according to the present invention;

[0042] Figure 9 This is a schematic diagram of the spaced-apart muffler split-flow structure of the present invention;

[0043] Wherein: 1-Low-frequency sound-absorbing module; 2-Mid-high frequency sound-absorbing module; 3-Substation ventilation opening; 11-Box; 12-Insertion tube; 121-Small hole. Detailed Implementation

[0044] To better understand the present invention, the following description, in conjunction with the accompanying drawings, will further illustrate the invention.

[0045] like Figure 4 , Figure 7-9As shown, a composite sound-absorbing silencer includes: a low-frequency sound-absorbing module 1 and a medium- and high-frequency sound-absorbing module 2 installed in the ventilation opening 3 of the substation;

[0046] The low-frequency sound-absorbing module 1 adopts an internal tube superstructure design to absorb the first frequency noise radiated from the transformer body;

[0047] The mid-to-high frequency sound-absorbing module 2 absorbs noise from the second frequency band radiated from the transformer body through frictional loss.

[0048] The frequency of noise in the first frequency band is lower than the frequency of noise in the second frequency band.

[0049] There are multiple low-frequency sound-absorbing modules 1 and multiple mid-to-high-frequency sound-absorbing modules 2.

[0050] The first frequency band noise includes single-frequency noise in the range of 100 to 500 Hz; the second frequency band noise includes mid-to-high frequency noise in the range of 500 to 2000 Hz.

[0051] like Figure 1 and Figure 2 As shown, the low-frequency sound-absorbing module 1 includes: a box body 11 and a tube 12. The side of the box body 11 facing the sound source has at least one through hole for inserting the tube 12. Each side of the box body 11 is made of galvanized sheet.

[0052] The low-frequency sound-absorbing module 1 measures 130mm × 100mm, the insertion tube 12 has a length of 3.4mm to 77.4mm, and the small hole 121 is a rectangular or circular hole.

[0053] When low-frequency sound waves of 100–500 Hz reach the substation ventilation opening 3, they first impact the housing 11. As the sound waves pass through the through-hole in the housing 11, some of the low-frequency sound energy is converted into airflow. The sound waves then enter the hollow cavity formed inside the housing through the through-hole, providing a space for resonance. The insertion tube 12 is inserted into the housing 11, with one end closed and the other end open.

[0054] like Figure 3 As shown, the insertion tube 12 has an opening at one end outside the housing 11, and a small hole 121 is provided on the side wall or bottom of the insertion tube 12 inside the housing 11. A resonant acoustic cavity is formed between the cavity of the low-frequency sound-absorbing module 1 and the insertion tube 12. When the frequency of the incident sound wave is close to the natural frequency of the low-frequency sound-absorbing module 1, the air in the acoustic cavity resonates with the sound wave, consuming the sound wave energy. The sound absorption frequency is adjusted by the position and size of the small hole 121 on the insertion tube 12, thereby achieving the absorption of noise at a specific frequency. At the same time, the resonant cavity sound absorption structure meets environmental protection requirements.

[0055] After multiple reflections and absorptions, the energy of the sound wave gradually attenuates, and by the time it passes through the other end of the silencer, the noise level has been significantly reduced.

[0056] After the sound wave enters the low-frequency sound-absorbing module 1, the energy of the sound wave is gradually converted into heat energy through friction and viscous resistance in the pores of the sound-absorbing material.

[0057] The mid-to-high frequency sound-absorbing module 2 includes: a shell composed of plates and its internal filling material. The plates include porous sound-absorbing panels, which are made of porous galvanized sound-absorbing material with a thickness of approximately 100 mm. The pore size of the porous sound-absorbing panels is 0.1 mm to 1 mm, and the perforation rate is 0.1% to 30%. The plates include galvanized steel sheets, and the filling material is selected from at least one of rock wool and glass fiber wool.

[0058] Mid-to-high frequency sound waves pass through the panel, where the size and distribution of the small holes are designed to maximize sound wave capture and absorption. The porous sound-absorbing panel is filled with rock wool or glass fiber wool, materials with high porosity and low density, which can effectively absorb sound waves. When sound waves enter the filling material, they propagate in the pores inside the material. Due to friction and the viscous resistance of air molecules, the energy of the mid-to-high frequency sound waves is gradually converted into heat energy.

[0059] Multiple low-frequency sound-absorbing modules 1 and multiple medium- and high-frequency sound-absorbing modules 2 are fixed inside the substation ventilation openings 3 in a cross-shaped or spaced arrangement.

[0060] The silencer uses a flange, with a sealing plate attached to the flange end face. The silencer flange is fixed to the wall with expansion bolts, thus enabling quick installation and disassembly.

[0061] like Figure 4 As shown, when multiple low-frequency sound-absorbing modules 1 and multiple mid-to-high-frequency sound-absorbing modules 2 are arranged in a cross shape, the multiple low-frequency sound-absorbing modules 1 are arranged in a cross structure on a plane.

[0062] Multiple mid-to-high frequency sound-absorbing modules 2 are evenly filled between the outer and inner walls of the cross, and are located on the same plane as the low-frequency sound-absorbing module 1. The porous sound-absorbing panel is reinforced with ribs around its perimeter.

[0063] The cross-shaped low-frequency sound-absorbing module 1 has internal insertion tubes on both sides, forming an internal insertion slit-type sound-absorbing superstructure.

[0064] Low-frequency sound waves have long wavelengths, so fewer arrays are needed. The low-frequency sound-absorbing modules 1 are arranged in a cross shape on the perforated plate 11, forming a cross-shaped low-frequency sound-absorbing module plate. This arrangement helps cover a wider frequency range. Reinforcing ribs 5 are located around the perforated sound-absorbing panel to enhance its structural strength and rigidity, preventing deformation under high pressure or high wind speeds. Figure 6 As shown in CC, internal tubes are provided at opposite ends of the cross-shaped low-frequency sound-absorbing module 1, and these internal tubes form an internal slot-type sound-absorbing superstructure; as Figure 5As shown in BB, the other two ends are single flat plates, and the design of the internal tubes increases the complexity of the muffler, which helps to further absorb and disperse sound waves and improve the absorption efficiency of low-frequency noise.

[0065] This composite sound-absorbing silencer design, by combining a low-frequency sound-absorbing module 1 and a mid-to-high-frequency sound-absorbing module 2, can achieve effective control of broadband noise.

[0066] When sound waves reach the cross-shaped silencer ventilation opening in the substation, after entering the silencer interior, low-frequency sound waves enter the resonant cavity of the low-frequency sound-absorbing module 1. Part of the sound energy is converted into airflow, which is then absorbed by the air layer within the resonant cavity and converted into heat energy. Simultaneously, because the cross-shaped low-frequency sound-absorbing module plate has internally inserted tubes on opposite sides, these tubes form an internally inserted slot-type sound-absorbing superstructure, which helps to further absorb and disperse sound waves, improving the absorption efficiency of low-frequency noise. At the same time, sound waves also come into contact with the porous sound-absorbing panel, which is distributed on the perforated plate 11 in other parts besides the low-frequency sound-absorbing module 1. The sound waves enter the interior of the porous sound-absorbing panel through small holes. The interior of the porous sound-absorbing panel is filled with rock wool or glass fiber wool, materials with high porosity and low density, which can effectively absorb mid-to-high frequency sound waves. As the sound waves propagate within the pores of the material, due to friction and the viscous resistance of air molecules, the energy of the sound waves is gradually converted into heat energy.

[0067] The cross-shaped muffler, by combining low-frequency sound absorption module 1 and mid-to-high-frequency sound absorption module 2, can effectively control broadband noise, which not only improves sound absorption efficiency but also enhances the stability and durability of the structure.

[0068] The multiple low-frequency sound-absorbing modules 1 and the multiple mid-to-high-frequency sound-absorbing modules 2 are arranged in an alternating configuration, which can be either embedded or split-type.

[0069] like Figure 7-8 As shown, the spaced silencers can be configured as a straight-through type. When multiple low-frequency sound-absorbing modules 1 and multiple mid-to-high-frequency sound-absorbing modules 2 are configured in an embedded manner, the low-frequency sound-absorbing modules 1 are embedded in the filling material of the mid-to-high-frequency sound-absorbing modules 2. The number of layers of the square array plate is set according to the noise requirements. The first and last layers are set as composite array plates. Since the low-frequency wavelength is long, not many arrays are needed, and the middle layers can all be set as single array plates. If the resistance allows, composite arrays can be added in the middle for noise reduction.

[0070] The low-frequency sound-absorbing module 1 and the mid-to-high-frequency sound-absorbing module 2 are integrated with the main structure of the silencer to form a compact unit, which can save space and is suitable for space-constrained application scenarios. The embedded configuration can maintain the continuity of airflow and reduce airflow disturbance, thereby reducing airflow noise.

[0071] After entering the silencer, the sound waves pass through the porous sound-absorbing panel, where the rock wool or fiberglass wool inside absorbs some of the mid-to-high frequency sound waves. Then, they reach the low-frequency sound-absorbing module 1 and enter the perforated plate 11, where they absorb some of the low-frequency sound energy through the resonant cavity between the perforated plate and the panel. The sound waves then pass through the air layer between the panel and the back panel, providing additional resonant space to absorb excess low-frequency sound energy. After multiple reflections and absorptions, the sound wave energy gradually attenuates, and by the time it passes through the other end of the silencer, the noise level has been significantly reduced.

[0072] like Figure 9 As shown, when multiple low-frequency sound-absorbing modules 1 and multiple mid-to-high-frequency sound-absorbing modules 2 are configured in a split manner, the low-frequency sound-absorbing module 1 is located in the substation ventilation opening 3 at the end closest to the sound source, and the multiple low-frequency sound-absorbing modules 1 are arranged horizontally and closely to form a low-frequency sound-absorbing layer.

[0073] The mid-to-high frequency sound absorption module 2 is horizontally arranged adjacent to the low-frequency sound absorption layer and is located at the end furthest from the sound source, forming a composite sound absorption layer;

[0074] A single sound-absorbing layer consisting of a mid-to-high frequency sound-absorbing module 2, which is longitudinally and parallel to the composite sound-absorbing layer.

[0075] The first and last two layers of the substation ventilation opening 3 are equipped with composite sound-absorbing layers;

[0076] At least one low-frequency sound-absorbing layer is provided in the middle of the substation ventilation opening 3. The spaced silencers can be configured as curved, and their low-frequency sound-absorbing module 1 and mid-to-high frequency sound-absorbing module 2 are configured in a split manner. The number of square array plates is set according to the noise requirements. The first and last two layers are set as composite array plates. Since the low-frequency wavelength is long, not many arrays are needed, and the middle layers can all be set as single array plates. If the resistance allows, composite arrays can be added in the middle for noise reduction.

[0077] The silencer features an internal insertable modular porous sound-absorbing panel. Its split-flow configuration offers greater flexibility, allowing adjustment of each module's configuration to meet specific noise control needs. The split-flow design disperses airflow to different sound-absorbing modules, improving sound absorption efficiency. This configuration is suitable for complex airflow environments, such as bends and branched ventilation ducts, and better adapts to changes in airflow.

[0078] Noise generated by the indoor transformer and cooling fan radiates indoors. When this noise reaches the wall ventilation and cooling vents, the sound waves enter the vent's cross-section. These sound waves then enter the composite ventilation silencer. The first section of the silencer's wall utilizes a modular low-frequency sound-absorbing superstructure to absorb the transformer's 100-500Hz single-frequency noise. As the sound waves pass through this silencer section, the transformer's low-frequency radiated noise is reduced.

[0079] When the sound wave enters the second section of the silencer, it absorbs the mid-to-high frequency noise of the cooling fan through the internal insert-type porous sound-absorbing panel, thereby reducing the radiated noise of the cooling fan; and at the very end, it controls and suppresses the overall radiated noise, preventing the indoor transformer's noise from leaking out.

[0080] This invention, through the development of a super-structure composite ventilation silencer, can effectively suppress the noise radiated from the ventilation openings of conventional indoor transformers, facilitating the comprehensive management of transformer and fan noise in various indoor transformers, thereby achieving the following effects:

[0081] 1) The design and application of the composite ventilation silencer with super-structure can further suppress noise at the substation boundary;

[0082] 2) By conducting an early assessment of the noise at the ventilation openings, the low-frequency noise from the transformer can be suppressed at the source, thereby achieving comprehensive noise control from the propagation path at the source.

[0083] 3) The modular design of the low-frequency superstructure ensures the array design and production of different ventilation opening silencing structures;

[0084] 4) By combining the low-frequency superstructure with the traditional porous material modular structure, a comprehensive solution can be achieved for the noise control of transformers and fans.

[0085] 5) Based on current performance testing, this structure can achieve a noise reduction of more than 20dB.

[0086] The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of the claims of the present invention pending approval.

Claims

1. A composite sound-absorbing silencer, characterized in that, include: Low-frequency sound-absorbing module (1) and medium-high frequency sound-absorbing module (2) are installed in the ventilation opening (3) of the substation; The low-frequency sound-absorbing module (1) adopts an internal tube superstructure design to absorb the first frequency band noise radiated from the transformer body; The mid-to-high frequency sound-absorbing module (2) absorbs noise from the second frequency band radiated from the transformer body by means of frictional loss; The frequency of the noise in the first frequency band is lower than the frequency of the noise in the second frequency band.

2. The composite sound-absorbing silencer as described in claim 1, characterized in that, There are multiple low-frequency sound-absorbing modules (1) and multiple mid-to-high frequency sound-absorbing modules (2).

3. A composite sound-absorbing silencer as described in claim 2, characterized in that, Multiple low-frequency sound-absorbing modules (1) and multiple medium- and high-frequency sound-absorbing modules (2) are fixed in the substation ventilation opening (3) in a cross or spaced manner.

4. The composite sound-absorbing silencer as described in claim 1, characterized in that, The low-frequency sound-absorbing module (1) includes a housing (11) and a tube (12). The housing (11) has at least one through hole for inserting the tube (12) on the side facing the sound source.

5. A composite sound-absorbing silencer as described in claim 4, characterized in that, The box body (11) is made of galvanized sheet on each side.

6. A composite sound-absorbing silencer as described in claim 4, characterized in that, The insertion tube (12) has an opening at one end outside the box (11), and the insertion tube (12) inside the box (11) has a small hole (121) on its side wall or bottom.

7. A composite sound-absorbing silencer as described in claim 4, characterized in that, The length of the cannula (12) is 3.4 mm to 77.4 mm.

8. A composite sound-absorbing silencer as described in claim 6, characterized in that, The small hole (121) is a rectangular small hole or a circular small hole.

9. A composite sound-absorbing silencer as described in claim 1, characterized in that, The mid-to-high frequency sound-absorbing module (2) includes: a shell composed of a plate and its internal filling material, wherein the plate includes a porous sound-absorbing panel.

10. A composite sound-absorbing silencer as described in claim 9, characterized in that, The pore size of the porous sound-absorbing panel is 0.1mm to 1mm.

11. A composite sound-absorbing silencer as described in claim 9, characterized in that, The perforation rate of the porous sound-absorbing panel is 0.1% to 30%.

12. A composite sound-absorbing silencer as described in claim 9, characterized in that, The plate includes galvanized steel.

13. A composite sound-absorbing silencer as described in claim 9, characterized in that, The filling material is selected from at least one of rock wool and glass fiber wool.

14. A composite sound-absorbing silencer as described in claim 3, characterized in that, When the multiple low-frequency sound-absorbing modules (1) and the multiple mid-to-high frequency sound-absorbing modules (2) are arranged in the cross-shaped arrangement, the multiple low-frequency sound-absorbing modules (1) are arranged in a cross-shaped structure on a plane; Multiple mid-to-high frequency sound-absorbing modules (2) are evenly filled between the outer and inner walls of the cross, and are located on the same plane as the low-frequency sound-absorbing module (1).

15. A composite sound-absorbing silencer as described in claim 3, characterized in that, The multiple low-frequency sound-absorbing modules (1) and the multiple mid-to-high-frequency sound-absorbing modules (2) are arranged in a configuration that can be either embedded or split-type.

16. A composite sound-absorbing silencer as described in claim 15, characterized in that, When the multiple low-frequency sound-absorbing modules (1) and the multiple mid-to-high frequency sound-absorbing modules (2) are configured in the embedded manner, the low-frequency sound-absorbing module (1) is embedded in the filling material of the mid-to-high frequency sound-absorbing module (2).

17. A composite sound-absorbing silencer as described in claim 15, characterized in that, When multiple low-frequency sound-absorbing modules (1) and multiple mid-to-high frequency sound-absorbing modules (2) are configured in the split-type configuration, the low-frequency sound-absorbing module (1) is located in the substation ventilation opening (3) at one end close to the sound source, and the multiple low-frequency sound-absorbing modules (1) are arranged closely in the horizontal direction to form a low-frequency sound-absorbing layer; The mid-to-high frequency sound absorption module (2) is arranged horizontally adjacent to the low frequency sound absorption layer and is located at the end away from the sound source, forming a composite sound absorption layer; The mid-to-high frequency sound absorption module (2) forms a single sound absorption layer, and the mid-to-high frequency sound absorption module (2) is arranged longitudinally parallel to the composite sound absorption layer. The first and last two layers of the substation ventilation opening (3) are provided with the composite sound-absorbing layer; The substation ventilation opening (3) shall have at least one low-frequency sound-absorbing layer in the middle.

18. A composite sound-absorbing silencer as described in any one of claims 1-17, characterized in that, The first frequency band noise includes single-frequency noise of 100 to 500 Hz; the second frequency band noise includes mid-to-high frequency noise of 500 to 2000 Hz.

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