Self-adaptive low-frequency noise reduction transformer cooling fan and control method

Abstract

The invention discloses a self-adaptive low-frequency noise reduction transformer cooling fan and a control method, relates to the technical field of transformer noise reduction, and is used for solving the problem of low-frequency noise dynamic suppression in an existing transformer substation transformer noise reduction mode. The cooling fan comprises a fan body, a mechanical noise reduction module, an acoustic processing module, a state detection module and an intelligent control module, the intelligent control module sends an instruction to an execution mechanism according to data transmitted by the state detection module, the execution mechanism receives the instruction to adjust the attack angle of a composite noise reduction blade, and vibration noise is restrained from the source; and the execution mechanism receives an instruction and attenuates sound energy from a propagation path by changing the opening degree of the spiral micro-channel. Vibration noise is suppressed from a noise generation source through the mechanical noise reduction module, air noise is attenuated from a propagation path through the acoustic processing module, and optimal noise reduction under all working conditions is achieved by adjusting the attack angle of the composite noise reduction blade or the opening degree of the spiral micro-channel in real time.

Description

Technical Field

[0001] The present invention relates to the technical field of transformer noise reduction in substations, and in particular to a transformer cooling fan with adaptive low-frequency noise reduction and a control method thereof. Background Art

[0002] During substation transformer operation, cooling fans are a major source of noise. Their noise spectrum is primarily low-frequency, ranging from 100 Hz to 500 Hz. Traditional noise reduction methods typically involve installing soundproof enclosures and standard mufflers, but these methods have the following drawbacks.

[0003] (1) Poor low-frequency noise suppression effect: Traditional sound-absorbing materials are effective for high-frequency noise, but have limited attenuation for low-frequency noise.

[0004] (2) Large size affects heat dissipation: The muffler has a complex structure and may block the air duct, reducing cooling efficiency.

[0005] (3) Unable to adapt to variable speed conditions: The noise characteristics of variable frequency fans change at different speeds, and fixed noise reduction solutions are difficult to optimize.

[0006] (4) Difficulty in maintenance: The noise reduction structure is difficult to disassemble and assemble, which increases operation and maintenance costs.

[0007] Existing technologies address these shortcomings by optimizing blades or muffler structures, but they fail to address the dynamic suppression of low-frequency noise. Active noise reduction algorithms also suffer from latency, leading to failure of substation electromagnetic compatibility control. Therefore, a cooling fan with adaptive, compact, and efficient low-frequency noise reduction is urgently needed. Summary of the Invention

[0008] The purpose of the present invention is to propose a transformer cooling fan with adaptive low-frequency noise reduction and a control method, which are used to solve the problem of dynamic suppression of low-frequency noise under the existing substation transformer noise reduction method.

[0009] The technical solution adopted by the present invention to solve the technical problem is: a transformer cooling fan with adaptive low-frequency noise reduction, including a fan body and the following modules.

[0010] A mechanical noise reduction module includes a composite noise reduction blade.

[0011] The acoustic processing module includes a muffler with a compact spiral microchannel integrated on a volute of a fan body.

[0012] State detection module: The state detection module includes a speed sensor for detecting the fan speed, a sound pressure sensor for detecting the transformer noise spectrum, and a vibration sensor for detecting the transformer vibration data.

[0013] Intelligent control module: The intelligent control module includes a controller and an actuator. The controller is signal-connected to the sound pressure sensor, the speed sensor, the vibration sensor, and the actuator. The controller sends instructions to the actuator based on the data transmitted by the status detection module. The actuator receives the instructions to adjust the angle of attack of the composite noise reduction blade to suppress vibration noise from the source; and the actuator receives the instructions to attenuate the sound energy from the propagation path by changing the opening and closing degree of the spiral microchannel.

[0014] Furthermore, the composite noise reduction blade has a bionic serrated trailing edge.

[0015] Furthermore, the serration height of the composite noise reduction blade is 2% of the blade chord length, and the serration spacing is 5 mm, which breaks up the tail vortex and reduces turbulent noise.

[0016] Furthermore, the leading edge of the composite noise reduction blade has perforations.

[0017] Furthermore, the inner wall of the perforation is coated with damping glue to suppress vibration conduction.

[0018] Furthermore, the perforation diameter is 3 mm and the perforation spacing is 12 mm; a Helmholtz resonance cavity is formed to absorb sound energy of 100 Hz-300 Hz low-frequency noise through air resonance.

[0019] Furthermore, the spiral microchannel has a tapered structure from the inlet to the outlet, with the inlet having a width of 15 mm and a depth of 10 mm, and the outlet having a width of 12 mm and a depth of 8 mm; the total length of the spiral microchannel is 1.2 m.

[0020] Furthermore, the inlet end of the spiral microchannel is filled with metal foam, the middle part of the spiral microchannel is filled with porous ceramics, and the outlet end of the spiral microchannel is filled with polyurethane; the metal foam absorbs high-frequency noise, the porous ceramics absorb medium-frequency noise, and the polyurethane targets and absorbs low-frequency noise, thereby achieving coverage of key noise frequency bands.

[0021] Furthermore, a magnetic snap-fit ​​assembly structure is provided between the composite noise reduction blade and the fan body, and a slide rail plug-in structure is provided between the muffler and the fan body.

[0022] The present invention also provides a control method for a transformer cooling fan with adaptive low-frequency noise reduction, which includes the following steps.

[0023] S1. The fan speed data is collected in real time through the speed sensor, the noise spectrum data of the transformer is collected in real time through the sound pressure sensor, and the vibration data of the transformer is collected in real time through the vibration sensor, and the above data are uploaded to the intelligent control module in real time.

[0024] S2. The intelligent control module adjusts the attack angle of the composite noise reduction blade and / or the opening and closing degree of the spiral microchannel according to the fan speed, transformer noise spectrum data and transformer vibration data.

[0025] The beneficial effects of the present invention are as follows: the present invention adjusts the angle of attack of the composite noise reduction blade and the opening and closing degree of the spiral microchannel by real-time detection of the fan speed and transformer vibration data, thereby achieving adaptive noise reduction of low-frequency noise. This is mainly reflected in: (1) the use of composite noise reduction blades: the composite noise reduction blades adopt a bionic serrated trailing edge to suppress medium and high-frequency eddy current noise; and adopt a perforated structure to achieve targeted absorption of low-frequency noise. (2) the use of a muffler with spiral microchannels: spiral microchannels are set on the inner wall of the volute of the fan body, and low-frequency attenuation is enhanced by sound wave interference and gradient-set sound-absorbing materials. (3) Source-path collaborative control: the mechanical noise reduction module suppresses vibration noise from the source of noise generation, and the acoustic processing module attenuates air noise from the propagation path. By adjusting the angle of attack of the composite noise reduction blades or the opening and closing degree of the spiral microchannels in real time, optimal noise reduction is achieved under all working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a noise suppression process diagram of the present invention.

[0027] Figure 2 This is the dynamic parameter matching diagram of the present invention. DETAILED DESCRIPTION

[0028] like Figure 1 、 Figure 2 As shown, the present invention provides a transformer cooling fan with adaptive low-frequency noise reduction and a control method. This fan utilizes a four-layer detachable modular architecture, with each module working collaboratively to implement a closed-loop control system known as "perception-decision-execution-verification." This achieves a triple breakthrough in low-frequency noise reduction, heat dissipation maintenance, and intelligent adaptation. The structure, operating principle, and control method of the present invention are described in detail below with reference to the accompanying drawings.

[0029] like Figure 1 As shown, a transformer cooling fan with adaptive low-frequency noise reduction includes a fan body, a mechanical noise reduction module, an acoustic processing module, a state detection module and an intelligent control module.

[0030] 1. Fan body.

[0031] The diameter of the fan body is 450mm-500mm, with an allowable processing tolerance of ±0.8mm, matching the IEC 60601-2-20 standard flange.

[0032] The axial length of the fan body is 280 mm, and the allowable processing tolerance is ±0.5 mm, which meets the space constraints of the transformer cabinet.

[0033] The fan body's mounting interface uses M12 bolts, H7 / g6 fit, and is connected to a DIN 929 standard flange.

[0034] For the fan body, the thermal properties of the material must meet the requirements of thermal deformation temperature: 160°C and linear expansion coefficient: 2.3×10 -5 / ℃.

[0035] For the fan body, the material corrosion resistance must meet the salt spray test: no corrosion for 3000 hours; UV aging must meet the following requirements: ΔE<1.5 under 2000 hours of QUV test.

[0036] For the fan body, the structural mechanical properties of its material must meet Table 1.

[0037]

[0038] 2. Mechanical noise reduction module.

[0039] The mechanical noise reduction module includes composite noise reduction blades made of carbon fiber-reinforced nylon, offering both lightweight and high strength. These blades feature a bionic serrated trailing edge. The serrations are 2% of the blade chord length, ideally 10 mm, with a 5 mm pitch. The trailing edge of the blades mimics the shape of an owl feather to break up wake vortices and reduce turbulent noise. This reduces mid- and high-frequency noise by 4-6 dB.

[0040] For composite noise reduction blades, the thermal properties of the material must meet the following requirements: thermal deformation temperature: 215°C, linear expansion coefficient: 2.3×10 -5 / ℃.

[0041] For composite noise reduction blades, the structural mechanical properties of the material must meet Table 2.

[0042]

[0043] The leading edge of the composite noise-reduction blade features several perforations, each 3mm in diameter and 12mm apart, forming a Helmholtz resonance cavity. This absorbs low-frequency noise energy from 100Hz to 300Hz through air resonance. Damping adhesive is applied to the inner walls of the perforations to suppress vibration transmission.

[0044] The fan torsion angle of the composite noise reduction blade adopts the structural design shown in Table 3.

[0045]

[0046] The manufacturing process of the composite noise reduction blade is described below.

[0047] (1) Mold design.

[0048] Parting surface selection: Parting along the maximum chord length position to reduce demoulding force.

[0049] Demolding angle: 1.2° on the pressure side and 1.5° on the suction side to compensate for shrinkage deformation.

[0050] Surface treatment: mirror polishing (Ra≤0.1μm) + spraying DLC ​​coating.

[0051] (2) Molding process.

[0052] The molding process, parameters and quality requirements are shown in Table 4.

[0053]

[0054] (3) Post-processing process.

[0055] ①Dynamic balance correction.

[0056] Permissible residual unbalance: 0.8g·cm.

[0057] Correction method: laser de-weighting, depth <0.3mm.

[0058] ②Surface coating.

[0059] Primer: Epoxy conductive paint, thickness 50μm.

[0060] Topcoat: Polyurethane oleophobic coating, contact angle >150°

[0061] 3. Acoustic processing module.

[0062] The acoustic treatment module includes a muffler with compact spiral microchannels integrated into the turbine's volute. The microchannels feature a tapered design, decreasing in size from inlet to outlet. The inlet is 15mm wide and 10mm deep, while the outlet is 12mm wide and 8mm deep. The total length of the microchannels is 1.2m, with eight spiral turns.

[0063] The spiral microchannels are filled with a gradient-filled sound-absorbing material. Specifically, the inlet is filled with metal foam, such as aluminum fiber; the middle is filled with porous ceramic; and the outlet is filled with polyurethane. The metal foam absorbs high-frequency noise, the porous ceramic absorbs mid-frequency noise, and the polyurethane targets low-frequency noise, effectively covering key frequency bands. The spiral microchannels have a base pitch of 12°, with an adaptive adjustment range of 10°-15°.

[0064] The spiral microchannel extends the sound path by adopting a tapered structural design and a spiral structure, so that opposite phase sound waves cancel each other out.

[0065] For the sound-absorbing material filled in the spiral microchannel, the sound absorption coefficient must meet the requirements of Table 5.

[0066]

[0067] The manufacturing process of the muffler is described below.

[0068] (1) Precision machining.

[0069] The PCD ball end mill is used for the finishing part of the muffler, and the diamond coated end mill is used for the roughing part. The cutting parameters are shown in Table 6.

[0070]

[0071] (2) Material composite.

[0072] ①Interface processing.

[0073] Plasma cleaning: cleaning speed 100W / 5min.

[0074] Primer: Silane coupling agent is used.

[0075] ②Curing process.

[0076] Step heating: The heating method is 80℃(1h)→120℃(2h)→160℃(1h).

[0077] Vacuum degree: ≤10 -2 Pa.

[0078] 4. Status detection module.

[0079] The status detection module includes a speed sensor, a sound pressure sensor and a vibration sensor to monitor the vibration of the transformer.

[0080] The speed sensor is used to detect the fan speed in real time, the sound pressure sensor is used to detect the transformer noise spectrum in real time, and the vibration sensor is used to detect transformer vibration data in real time. The specific specifications of the speed sensor, sound pressure sensor, and vibration sensor are shown in Table 7.

[0081]

[0082] The controllers that match the above speed sensors, sound pressure sensors, and vibration sensors must meet the following requirements.

[0083] (1) Main chip: TI TMS320F28379D.

[0084] (2) Real-time performance.

[0085] Interrupt response time: <500ns.

[0086] FFT calculation period: 1.2ms.

[0087] (3) Storage configuration.

[0088] Flash memory: 1MB, parameter database.

[0089] RAM: 512KB, real-time cache.

[0090] The requirements for data collection of each sensor are shown in Table 8.

[0091]

[0092] The data collected by each sensor is preprocessed. The preprocessing requirements are shown in Table 9.

[0093]

[0094] Table 10 shows the contents of spectrum analysis operations for data collected by the sound pressure sensor.

[0095]

[0096] 5. Intelligent control module.

[0097] The intelligent control module includes a controller and an actuator. Signal connections are established between the controller and the sound pressure sensor, the speed sensor, the vibration sensor, and the actuator. Based on data from the status detection module, the controller sends instructions to the actuator, which then adjusts the angle of attack of the composite noise-reduction blades, suppressing vibration noise at its source. Furthermore, the actuator receives instructions to attenuate sound energy along the propagation path by varying the opening and closing of the spiral microchannels.

[0098] Table 11 shows the adjustment strategies for the attack angle of the composite noise reduction blade and the opening and closing degree of the spiral microchannel at different fan speeds.

[0099]

[0100] The working mode of the intelligent control module is shown in Table 12.

[0101]

[0102] To facilitate the rapid assembly and disassembly between the fan body and the composite noise reduction blades, and between the muffler and the fan body, a magnetic snap-on assembly structure is used between the composite noise reduction blades and the fan body, and a sliding rail plug-in structure is used between the muffler and the fan body.

[0103] The following is a detailed description of the magnetic clip assembly structure between the composite noise reduction blades and the fan body.

[0104] (1) Magnetic snap-on principle: Utilizes the suction force provided by a strong permanent magnet, such as NdFeB N52, to achieve initial fixation and accurate positioning, combined with a mechanical locking pin / spring-loaded claw to provide the primary anti-vibration and anti-torque connection strength. The strong permanent magnet's suction force is responsible for overcoming the blade's gravity and assisting in alignment.

[0105] (2) Detailed structural composition.

[0106] ① Hub interface: The hub end is designed as a boss structure with a locating pin hole and a magnet mounting slot / hole.

[0107] ②Blade root interface.

[0108] Strong permanent magnets are embedded in specific locations at the blade root, corresponding to the hub magnets. The magnets are covered with a thin layer of corrosion-resistant, non-magnetic material, such as stainless steel or engineering plastics.

[0109] Locking Pin / Claw Groove: A receiving hole or locking groove that mates with the locking pin / claw on the wheel hub.

[0110] Guide bevel: facilitates automatic guidance and alignment when inserting the wheel hub.

[0111] ③Locking pin / claw mechanism located on the wheel hub.

[0112] Locking pin / claw: has a beveled or wedge-shaped structure and is manually pulled or rotated by the operator.

[0113] Spring: Provides locking force, the compression spring travel must be sufficient to release the blade.

[0114] Operating handle / pull ring: Releases the locking mechanism.

[0115] (3) Steps and procedures for removing blades.

[0116] ①The operator presses or rotates the operating handle / pull ring on the wheel hub.

[0117] ②The locking pin / claw is pulled back into the wheel hub to unlock.

[0118] ③ Since the strong permanent magnet suction is only used to assist positioning, the blades can be separated from the hub under their own gravity or light pulling.

[0119] ④The operator removes the blades with bare hands.

[0120] (4) Key design points.

[0121] ① Calculation of the strength of strong permanent magnets: The suction force must be > 3 times the weight of the blade to ensure safe handling and positioning, and < the maximum locking force to ensure that the locking mechanism is the main load-bearing component.

[0122] ② Locking force design: The mechanical locking structure must provide a locking force that is much greater than the maximum aerodynamic torque / centrifugal force during operation and pass strength verification calculations.

[0123] ③ Anti-misoperation: The locking mechanism has an anti-loosening design, such as ratchet and self-locking bevel.

[0124] ④Material compatibility: All metal parts must be resistant to salt spray corrosion and use stainless steel or spray coating. Plastic parts must be resistant to UV and high temperature.

[0125] The following describes the sliding rail plug-in structure between the muffler and the fan body.

[0126] (1) Principle: The entire muffler is designed as an independent drawer-type unit, which is inserted and withdrawn from the fan volute through precision-machined slide rails, such as linear bearings. The rear end connection uses a quick-plug hose connector and an electrical connector.

[0127] (2) Detailed structural composition.

[0128] ①Muffler module: includes a metal matrix, an internal spiral microchannel structure, a filled gradient sound-absorbing material, and an actuator interface.

[0129] ② Volute cavity: A rectangular cavity is set on the side of the volute of the fan body or at a specific location to accommodate the muffler. The cavity includes two sides of the slide rail mounting surface and a positioning surface.

[0130] ③ Precision slide rail assembly: Use at least two pairs of heavy-duty linear ball bearing slide rails. The rails are fixed to the sides of the volute cavity, and the sliders are fixed to the sides of the muffler module. The rails must have limit stops to prevent them from being completely pulled off.

[0131] ④ Sealing structure: After the muffler module is inserted into place, its periphery is compressed by a sealing ring, such as silicone rubber, to achieve an airtight seal between the volute air duct.

[0132] ⑤Quick plug connector.

[0133] Module end: Set up male or female quick-connect connector, made of metal or engineering plastic.

[0134] Volute end: matching female or male quick-connect connector.

[0135] Requirements: With O-ring seal and self-locking mechanism, it can be locked when plugged in and released by pressing or rotating.

[0136] ⑥Quick plug electrical connector: with multiple pins, used to power the solenoid valve or sensor and communicate via RS485 / CAN, with foolproof design.

[0137] ⑦ Locking device: After the muffler module is fully inserted, it is locked in the volute cavity by a simple and reliable lock or rotating handle to prevent it from loosening and popping out during operation. The locking device is usually integrated into the maintenance panel on the front of the muffler module.

[0138] like Figure 2 As shown, a control method for a transformer cooling fan with adaptive low-frequency noise reduction of the present invention includes the following steps.

[0139] S1. The fan speed data is collected in real time through the speed sensor, the transformer noise spectrum data is collected in real time through the sound pressure sensor, and the transformer vibration data is collected in real time through the vibration sensor. The above data are uploaded to the intelligent control module in real time.

[0140] S2. The intelligent control module adjusts the attack angle of the composite noise reduction blade and / or the opening and closing degree of the spiral microchannel according to the fan speed, transformer noise spectrum data and transformer vibration data.

[0141] The beneficial effects of the present invention are: (1) Use of composite noise reduction blades: The composite noise reduction blades adopt a bionic serrated trailing edge to suppress medium and high frequency eddy current noise; and adopt a perforated structure to achieve targeted absorption of low frequency noise. (2) Use of a muffler with spiral microchannels: A spiral microchannel is set on the inner wall of the volute of the fan body, and low frequency attenuation is enhanced through sound wave interference and gradient sound absorption materials. (3) Source-path collaborative control: The mechanical noise reduction module suppresses vibration noise from the source of noise generation, and the acoustic processing module attenuates air noise from the propagation path. By real-time adjustment of the composite noise reduction blade attack angle or the opening and closing degree of the spiral microchannel, optimal noise reduction is achieved in all working conditions. (4) Quick maintenance design: The muffler of the acoustic processing module adopts a magnetic snap-on structure, and the composite noise reduction blades of the mechanical noise reduction module adopt a slide rail plug-in structure, which can be replaced without tools and is convenient for assembly and disassembly.

Claims

1. A transformer cooling fan with adaptive low-frequency noise reduction, comprising a fan body, characterized in that: Also includes: A mechanical noise reduction module, the mechanical noise reduction module comprising a composite noise reduction blade; An acoustic processing module, the acoustic processing module comprising a muffler with a compact spiral microchannel integrated on a volute of a fan body; Status detection module: The status detection module includes a speed sensor for detecting the fan speed, a sound pressure sensor for detecting the transformer noise spectrum, and a vibration sensor for detecting the transformer vibration data; Intelligent control module: The intelligent control module includes a controller and an actuator. The controller is signal-connected to the sound pressure sensor, the speed sensor, the vibration sensor, and the actuator. The controller sends instructions to the actuator based on the data transmitted by the status detection module. The actuator receives the instructions to adjust the angle of attack of the composite noise reduction blade to suppress vibration noise from the source; and the actuator receives the instructions to attenuate the sound energy from the propagation path by changing the opening and closing degree of the spiral microchannel.

2. The transformer cooling fan with adaptive low-frequency noise reduction according to claim 1, characterized in that: The composite noise reduction blade has a bionic serrated trailing edge.

3. The transformer cooling fan with adaptive low-frequency noise reduction according to claim 2, characterized in that: The serration height of the composite noise reduction blade is 2% of the blade chord length, and the serration spacing is 5 mm.

4. The transformer cooling fan with adaptive low-frequency noise reduction according to claim 3, characterized in that: The leading edge of the composite noise reduction blade is provided with perforations.

5. The transformer cooling fan with adaptive low-frequency noise reduction according to claim 4, characterized in that: The inner wall of the perforation is coated with damping glue.

6. The transformer cooling fan with adaptive low-frequency noise reduction according to claim 5, characterized in that: The perforation diameter is 3 mm and the perforation spacing is 12 mm, forming a Helmholtz resonance cavity, which absorbs sound energy of 100 Hz-300 Hz low-frequency noise through air resonance.

7. The transformer cooling fan with adaptive low-frequency noise reduction according to claim 6, characterized in that: The spiral microchannel has a tapered structure from the inlet to the outlet, with a width of 15 mm and a depth of 10 mm at the inlet, and a width of 12 mm and a depth of 8 mm at the outlet; the total length of the spiral microchannel is 1.2 m.

8. The transformer cooling fan with adaptive low-frequency noise reduction according to claim 7, characterized in that: The inlet end of the spiral microchannel is filled with metal foam, the middle part of the spiral microchannel is filled with porous ceramics, and the outlet end of the spiral microchannel is filled with polyurethane.

9. The transformer cooling fan with adaptive low-frequency noise reduction according to claim 8, characterized in that: A magnetic snap-fit ​​assembly structure is provided between the composite noise reduction blade and the fan body, and a slide rail plug-in structure is provided between the muffler and the fan body.

10. The control method for a transformer cooling fan with adaptive low-frequency noise reduction according to claim 9, characterized in that: The following steps are involved: S1. Collect fan speed data in real time through the speed sensor, collect transformer noise spectrum data in real time through the sound pressure sensor, and collect transformer vibration data in real time through the vibration sensor, and upload the above data to the intelligent control module in real time; S2. The intelligent control module adjusts the attack angle of the composite noise reduction blade and / or the opening and closing degree of the spiral microchannel according to the fan speed, transformer noise spectrum data and transformer vibration data.

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