A noise reduction device and method for a wind turbine gearbox brake system

Abstract

The application provides a noise reduction device and method for a gear box brake system of a wind turbine, belonging to the technical field of wind power generation, comprising a shell, a vibration isolation structure, a multi-layer noise reduction structure and a monitoring control module. One end of the shell is connected to a generator through a connecting disc with a first rubber medium, and the other end is connected to a gear box clamp and a high-speed shaft through second and third rubber media respectively, achieving comprehensive vibration isolation. The shell is hollow, and the inner wall is sequentially embedded with a metal layer, a sound absorbing medium and an external sound insulation medium to absorb and isolate noise. A first sensor bracket is provided on the shell to install a noise and temperature sensor into the interior, and a second sensor bracket is provided to install a first and a second active noise reduction mechanism. The device reduces noise from the source through a composite damping and sound absorption and insulation structure, and realizes intelligent monitoring and accurate noise reduction in combination with sensors and active noise reduction, reduces the noise of the gear box brake system and improves the equipment operating environment.

Description

Technical Field

[0001] This invention belongs to the field of wind power generation technology, and specifically relates to a noise reduction device and method for a wind turbine gearbox braking system. Background Technology

[0002] With the increasing size of wind turbine generators, noise pollution from these units is becoming increasingly serious. The noise from wind turbine generators mainly originates from mechanical noise, electromagnetic noise, and aerodynamic noise. Mechanical noise primarily comes from the gearbox, yaw system, and cooling system; electromagnetic noise mainly comes from the generator and converter; and aerodynamic noise mainly comes from the sweeping sound of the rotor blades.

[0003] In general, related solutions use a rigid metal-to-metal connection between the generator and the gearbox braking system. Vibrations generated by the generator are directly transmitted to the braking system housing through the metal contact surface. The forced vibration of the housing generates secondary noise, and long-term vibration transmission can loosen the connecting bolts. Furthermore, vibration interferes with the braking accuracy of the braking system and exacerbates friction and wear on internal components. When the gearbox caliper, high-speed shaft end, and brake system housing are connected, the instantaneous impact vibration of the caliper during braking and the continuous vibration of the high-speed shaft act on the housing. The superposition of these different vibration sources causes resonance in the housing, generating high-frequency noise. Moreover, vibration transmission increases the gap at the connection points, further aggravating collision noise and component wear.

[0004] To detect noise, noise and temperature sensors are installed on the braking system. However, the sensing process is easily affected by external airflow and environmental noise, which can interfere with signal acquisition, leading to data distortion and an inability to accurately reflect the internal operating status of the braking system. This, in turn, affects the accurate formulation of subsequent active noise reduction control strategies. Summary of the Invention

[0005] This invention provides a noise reduction device for the gearbox braking system of a wind turbine generator set, which effectively reduces the noise level of the gearbox braking system. To effectively monitor internal temperature and noise changes, temperature and noise sensors are installed within the device, and temperature and noise warning thresholds are set. This effectively reduces the sound pressure level of the wind turbine generator set, reduces unplanned downtime, and extends the service life of components and equipment.

[0006] The device includes: a housing, the first end of which is connected to a generator via a connecting plate; The connection contact surface between the connecting plate and the generator is provided with a first rubber medium; One side of the second end of the housing is connected to the gearbox caliper, and the contact surface of the connection is provided with a second rubber medium; The second end of the housing is connected to the high-speed shaft end of the gearbox, and the contact surface of the connection is provided with a third rubber medium; The shell is a hollow structure, and a gearbox braking system is installed inside the hollow structure. The hollow structure has a metal layer embedded in its inner wall, and a sound-absorbing medium is installed inside the metal layer; a sound-insulating medium is installed on the outside of the metal layer.

[0007] Preferably, a first sensor bracket is installed near the first end of the housing; A noise sensor and a temperature sensor are mounted on the first sensor bracket; The sensing ends of the noise sensor and the temperature sensor extend into the housing to sense noise and temperature information inside the housing.

[0008] Preferably, a second sensor bracket is also mounted on the housing; The second sensor bracket is equipped with a first active noise reduction mechanism and a second active noise reduction mechanism.

[0009] Preferably, the housing has a first through hole, which is directly opposite the first active noise reduction mechanism.

[0010] Preferably, a second through hole is provided on the housing, and the second through hole is directly opposite the second active noise reduction mechanism.

[0011] The present invention also provides a noise reduction method, the method comprising: S101: The first end of the housing is connected to the generator via a connecting plate, wherein the connection contact surface between the connecting plate and the generator is provided with a first rubber medium; the second end of the housing is connected to the gearbox caliper and the high-speed shaft end face of the gearbox respectively, and the connection contact surface between the housing and the gearbox caliper is provided with a second rubber medium, and the connection contact surface between the housing and the high-speed shaft end face of the gearbox is provided with a third rubber medium. S102: Install a first sensor bracket near the first end of the housing, and insert the sensing ends of the noise sensor and temperature sensor into the housing through the housing; install a second sensor bracket on the housing, and install a first active noise reduction mechanism and a second active noise reduction mechanism on the second sensor bracket; connect the noise sensor, the first active noise reduction mechanism and the second active noise reduction mechanism to the noise analyzer respectively, connect the noise analyzer to the industrial control computer, and connect the industrial control computer to the fan control system PLC; S103: Set the sampling frequency of data acquisition to 2560Hz, and perform wavelet noise reduction preprocessing and spectral feature value analysis on the data acquired by the noise sensor through the industrial control computer; S104: Set thresholds for sound pressure levels in different frequency bands. When the decibel value in any frequency band exceeds the threshold, control the first active noise reduction mechanism and the second active noise reduction mechanism to open to reduce noise from the sound source inside the casing, and feed back the decibel value signal to the fan control system PLC at preset intervals. S105: When the internal temperature of the housing collected by the temperature sensor exceeds the preset temperature threshold, the fan speed is reduced by the fan control system PLC, and the temperature signal is fed back to the fan control system PLC at preset intervals. S106: When the decibel value in all frequency bands is less than the threshold, shut down the first active noise cancellation mechanism and the second active noise cancellation mechanism. S107: When the internal temperature of the casing is lower than the preset temperature threshold, the fan speed is restored to the normal speed through the fan control system PLC.

[0012] Preferably, S103 specifically includes the following steps: Configure the sampling parameters of the noise sensor using a data acquisition card, fix the sampling frequency at 2560Hz, and convert the analog noise signal into a digital signal sequence. The industrial control computer receives digital signal sequences through a serial communication interface and stores them as discrete-time signal data blocks in chronological order. Discrete wavelet transform is performed on the discrete-time signal data block, and multi-scale decomposition is performed using Daubechies wavelet basis functions to obtain the wavelet coefficients of each level. Based on the statistical characteristics of noise, a threshold is set, and soft threshold quantization is performed on the wavelet coefficients. Coefficients greater than the threshold are retained, and inverse discrete wavelet transform is performed on the quantized coefficients to reconstruct the denoised time domain signal. Perform a fast Fourier transform on the denoised time-domain signal, calculate the frequency amplitude spectrum, divide the frequency bands into equal bandwidths, and calculate the sound pressure level value in each frequency band as the spectral characteristic value.

[0013] Preferably, S104 specifically includes the following steps: S1041: Based on the noise frequency characteristics of the wind turbine generator gearbox braking system during operation, the noise frequency range is segmented using equal bandwidth or variable bandwidth methods to determine the frequency interval boundaries of each frequency segment. S1042: Based on the noise pressure level fluctuation range and noise reduction target of the gearbox braking system under normal operating conditions, set a sound pressure level threshold for each frequency band. S1043: The electrical signal output by the noise sensor is acquired in real time by the industrial control computer and converted into the sound pressure level value of the corresponding frequency band; S1044: Compare the real-time sound pressure level values ​​of each frequency band with the corresponding thresholds set in S1042 one by one to determine whether there is a sound pressure level in a certain frequency band that exceeds the frequency band threshold. S1045: When it is determined that the sound pressure level of any frequency band exceeds the threshold, an active noise reduction control command is generated and sent to the drive unit of the first active noise reduction mechanism and the second active noise reduction mechanism to drive the noise reduction mechanism to start; and at preset intervals, the current sound pressure level values ​​of each frequency band are packaged into signal frames and sent to the fan control system PLC.

[0014] Preferably, S1042 specifically includes the following steps: Under no-load, rated load and typical variable load conditions of wind turbine generator sets, the original noise time-domain signal of the gearbox braking system is collected by noise sensors and stored in the industrial control computer. The industrial control computer performs wavelet noise reduction preprocessing and fast Fourier transform on the stored raw noise time-domain signal to calculate the sound pressure level values ​​for each preset frequency band. For each preset frequency band, the mean normal noise sound pressure level and the standard deviation of noise sound pressure level fluctuation are calculated based on the sound pressure level values ​​of all operating conditions. Based on the upper limit of the allowable continuous noise sound pressure level in the gearbox area and the statistical characteristics of each frequency band, the operating sound pressure level threshold for each frequency band is calculated. Each frequency band and its corresponding operating sound pressure level threshold are stored in the industrial control computer as key-value pairs.

[0015] Preferably, S106 specifically includes the following steps: The industrial control computer collects the decibel values ​​of each frequency band in real time and compares them with the preset sound pressure level threshold of the corresponding frequency band to determine whether the decibel values ​​of all frequency bands are less than the threshold. The industrial control computer records the comparison results in each monitoring cycle. If the decibel values ​​of all frequency bands are less than the threshold, it is marked as meeting the requirements; otherwise, it is marked as not meeting the requirements. The industrial control computer is equipped with a timer. When the monitoring cycle mark meets the requirements, the cumulative time is incremented; when the mark does not meet the requirements, the cumulative time is reset. The industrial control computer checks the cumulative time, and generates a control command to shut down the active noise cancellation mechanism when the cumulative time reaches 30 minutes. The industrial control computer sends control commands to the drive units of the first and second active noise cancellation mechanisms, and the drive units perform a shutdown operation to stop the sound source cancellation action.

[0016] As can be seen from the above technical solutions, the present invention has the following advantages: The noise reduction device of the wind turbine gearbox braking system provided by the present invention has a housing first end connected to the generator through a connecting plate. A first rubber medium fills the connection contact surface, and uses the elastic deformation of the rubber to absorb the vibration of the generator operation and block the vibration from being transmitted to the housing. At the same time, the rubber medium evenly disperses the pressure at the connection part, reduces the bolt fastening stress, improves the fatigue resistance of the connection structure, and extends the service life of the connection parts.

[0017] The second end of the housing of the present invention is provided with a second and a third rubber medium on the connection surface with the gearbox caliper and the high-speed shaft end, respectively. The two rubber media are adapted to the force characteristics of different connection parts, and specifically absorb the braking impact vibration of the caliper and the running vibration of the high-speed shaft, so as to ensure the coaxiality of the connection between the housing and the gearbox components and reduce mechanical wear.

[0018] The hollow shell of this invention provides a closed installation space for the gearbox braking system, limiting the noise propagation range and preventing noise from directly spreading to the outside. The shell's structural strength supports the stable operation of the braking system, while also providing a mounting carrier for the internal noise reduction medium, external sensors, and noise reduction mechanisms. The sound-absorbing medium, metal layer, and sound-insulating medium on the inner wall of the shell form a triple noise reduction structure. The sound-absorbing medium dissipates sound wave energy through its porous structure, the metal layer reflects unabsorbed sound waves, causing secondary attenuation, and the sound-insulating medium blocks sound waves from transmitting to the outside of the shell. The triple structure works together to cover a wide range of noise, improving the noise reduction depth.

[0019] The first sensor bracket of this invention is fixed near the first end of the housing, providing a stable mounting reference for the noise sensor and temperature sensor. The sensing end of the sensor extends into the housing, directly contacting the internal environment, so the captured noise and temperature signals are not affected by external interference, resulting in high data accuracy. The sealed design of the mounting hole prevents noise leakage. The second sensor bracket provides precise mounting positioning for the first and second active noise reduction mechanisms. The bracket structure is strong enough to withstand the vibrations of the noise reduction mechanism during operation, ensuring the accurate emission direction of the reverse sound wave and improving the targeting of active noise reduction. Attached Figure Description

[0020] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 A schematic diagram of the noise reduction device structure of the gearbox braking system of a wind turbine generator set; Figure 2 This is a side view of the noise reduction device in the gearbox braking system of a wind turbine generator set. Figure 3 This is a schematic diagram of the overall structure of the noise reduction device; Figure 4 This is a schematic diagram of the side structure of the noise reduction device; Figure 5 This is a schematic diagram of an embodiment of the noise reduction device.

[0022] Explanation of reference numerals in the attached figures: 1. Connecting plate, 2. First rubber medium, 3. Second rubber medium, 4. Third rubber medium, 5. First sensor bracket, 6. Temperature sensor, 7. First through hole, 8. First active noise reduction mechanism, 9. Noise sensor, 10. Sound-absorbing medium, 11. Metal layer, 12. Sound-insulating medium, 13. Second through hole, 14. Second active noise reduction mechanism, 15. Second sensor bracket, 21. Housing. Detailed Implementation

[0023] The noise reduction device for the wind turbine gearbox braking system provided by this invention adopts a combination of active noise reduction, passive noise reduction, and monitoring. On the one hand, it reduces the noise of the wind turbine gearbox braking system during operation; on the other hand, it prevents the multiple sound sources in the braking system from emitting sound energy for extended periods during long-term operation of the unit, which could then be converted into heat energy inside the noise reduction device, reaching the ignition point of the internal sound-absorbing medium and causing a fire. The device has a simple structure, is easy to install and disassemble, and while reducing the decibel level of the wind turbine gearbox braking system, it also provides long-term monitoring and early warning functions.

[0024] The noise reduction device for the gearbox braking system of a wind turbine generator according to this application will be described in detail below. Specific details such as particular system structures and technologies are presented for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application can also be implemented in other embodiments without these specific details.

[0025] It should be understood that "one or more" as mentioned in this application refers to one, two, or more, and "multiple" as mentioned in this application refers to two or more. In the description of this application, unless otherwise stated, " / " means "or," for example, A / B can mean A or B. The "and / or" in this document is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone.

[0026] To facilitate a clear description of the technical solutions of this application, the terms "first" and "second" are used to distinguish identical or similar items with essentially the same function and effect. Those skilled in the art will understand that the terms "first" and "second" do not limit the quantity or execution order, and that the terms "first" and "second" do not necessarily imply that they are different.

[0027] The terms "one embodiment" or "some embodiments" used in this application mean that one or more embodiments of this application include the specific features, structures, or characteristics described in that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this application do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized.

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Please see Figures 1 to 5 The diagram shows a schematic of a noise reduction device for a wind turbine gearbox braking system in a specific embodiment. The device includes a housing 21. The first end of the housing 21 has an integrally formed annular flange structure. The connecting disc 1 is made of 45# steel, and one end of it is fastened to the housing flange by 8 sets of M high-strength bolts. The other end is provided with a connection end face adapted to the generator output end.

[0030] In this embodiment, the first rubber medium 2 is made of nitrile rubber with a Shore hardness of 55-60. It is processed into a ring structure with a thickness of 2.5mm. Its inner diameter is adapted to the positioning boss on the connecting end face of the connecting plate, and its outer diameter is consistent with the size of the connecting end face. During installation, circumferential positioning is achieved through the positioning boss, and it is pressed between the contact surfaces of the connecting plate and the generator.

[0031] As can be seen, the connecting plate 1, as a mechanical connection intermediate, achieves rigid fixation between the housing 21 and the generator through bolts. The first rubber medium 2 utilizes its own elastic deformation characteristics to buffer the vibration generated during generator operation, preventing the vibration from being directly transmitted to the housing through the metal contact surface, reducing secondary noise caused by vibration of the housing. The ring structure and the positioning boss work together to ensure accurate installation and prevent the rubber medium from shifting and affecting the buffering effect.

[0032] In some embodiments, two symmetrically arranged ear plates are welded to one side of the second end of the housing 21. The ear plates have through holes adapted to the gearbox caliper connection holes. The second rubber medium 3 is made of fluororubber with a temperature resistance range of -20℃ to 150℃. It is processed into a sheet structure with a thickness of 3mm and has clearance holes on its surface corresponding to the through holes of the ear plates. It is fastened by passing an internal hexagonal bolt through the ear plate, the rubber medium, and the caliper connection hole, and the rubber medium is pressed between the contact surfaces of the ear plate and the caliper.

[0033] Fluororubber's temperature and wear resistance properties are well-suited to the working environment of gearbox calipers. Its sheet-like structure fully covers the connection contact surface, and impact vibrations are absorbed by the elastic deformation of the rubber medium.

[0034] In some embodiments, a shaft hole adapted to the high-speed shaft end of the gearbox is machined at the center of the second end of the housing 21, with a fit tolerance of H7 / f6, and an annular mounting groove is formed on the end face of the shaft hole. The third rubber medium 4 is made of silicone rubber with an elastic modulus of 1.2MPa, machined into an annular structure with a thickness of 3mm, and embedded in the annular mounting groove. During installation, the flange face of the high-speed shaft end of the gearbox is in contact with the end face of the shaft hole, pressing the third rubber medium 4 into the mounting groove, and circumferentially fastened by 6 sets of M14 bolts.

[0035] In this embodiment, the clearance fit between the shaft hole and the high-speed shaft end achieves coaxial positioning. The third rubber medium 4 utilizes the high elasticity of silicone rubber to buffer the radial vibration and axial movement generated during the operation of the high-speed shaft, while simultaneously filling the gaps in the contact surface. The annular mounting groove enables precise positioning of the rubber medium and reduces noise caused by vibration.

[0036] In some embodiments, the housing 21 is welded from Q235 steel plate and is a hollow cylindrical structure with open ends. The inner diameter is 6mm larger than the maximum outer diameter of the gearbox brake system, and the wall thickness is 10mm. Eight positioning blocks are evenly distributed around the inner wall of the housing. The positioning blocks are welded and fixed to the inner wall of the housing. The end face of the positioning blocks is machined with positioning steps to fit the mounting flange of the gearbox brake system. The brake system is fixed to the positioning steps by bolts. The housing has detachable end caps at both ends. The end caps are connected to the housing flanges by bolts, and the inner side of the end caps is provided with sealing gaskets.

[0037] In some embodiments, the hollow cylindrical structure provides a closed installation space for the gearbox braking system, the positioning block enables precise positioning and fixation of the braking system, and the end cover and sealing gasket form a closed structure to limit the outward diffusion of noise. The positioning block ensures the braking system is securely installed, the removable end cover facilitates later maintenance and repair, and the sealing gasket further improves noise reduction and sealing performance.

[0038] In some embodiments, the metal layer 11 is made of 304 stainless steel sheet with a thickness of 1.2 mm. An annular groove is pre-reserved on the inner wall of the housing, and the metal layer is fixed in the groove by a snap-fit ​​method, fitting snugly against the inner wall of the housing. The sound-absorbing medium 10 is centrifugal glass wool with a density of 32 kg / m³ and a thickness of 25 mm. It is wrapped around the inner wall of the metal layer 11 and secured circumferentially with galvanized steel wire. The sound-insulating medium 12 is damping sound-insulating felt with a thickness of 6 mm. It is bonded to the outer wall of the metal layer 11 with butyl adhesive, fitting tightly against the inner wall of the housing without gaps.

[0039] As can be seen, the porous structure of the sound-absorbing medium 10 captures sound waves, and the energy of the sound waves is consumed by fiber friction when they propagate in the pores; the metal layer 11 reflects the unabsorbed sound waves, allowing them to re-enter the sound-absorbing medium 10 for secondary absorption; the sound-insulating medium 12 uses damping properties to block the transmission of sound waves to the outside of the shell. The reflective effect of the metal layer improves the sound absorption efficiency, and the damping sound-insulating felt blocks the sound wave transmission path. The synergistic effect of the three structures achieves all-round noise reduction.

[0040] In some embodiments, the first sensor bracket 5 is made of 6061 aluminum alloy in an L-shaped structure and is fixed to the outer wall of the housing 21 near the first end by four sets of M10 bolts. Two sensor mounting seats are machined on the horizontal end face of the bracket, respectively adapted to the noise sensor 9 and the temperature sensor 6. The noise sensor 9 is a piezoelectric sensor, and the temperature sensor 6 is a K-type thermocouple. Both are fixed to the mounting seats by threaded connections. The housing 21 has mounting holes corresponding to the mounting seat positions. The sensor sensing end passes through the mounting hole and extends into the housing, with a protruding length of 8mm. An O-ring is provided between the mounting hole and the sensor to achieve a seal.

[0041] As can be seen, the L-shaped bracket provides a stable mounting reference for the sensor, with the sensing end placed directly within the housing environment. Noise sensor 9 captures pressure changes caused by sound waves, and temperature sensor 6 senses the ambient temperature, converting physical signals into electrical signals for output. Since the sensing end directly contacts the internal environment, the captured noise and temperature signals accurately reflect the actual working conditions. The O-ring seal prevents noise leakage from affecting detection accuracy.

[0042] In some embodiments, the second sensor bracket 15 is made of 304 stainless steel and is U-shaped. It is fastened to the outer wall of the middle part of the housing 21 by six sets of M12 bolts, and the bolts are equipped with anti-loosening washers. The two parallel mounting surfaces of the bracket are machined with positioning pin holes. The first active noise reduction mechanism 8 and the second active noise reduction mechanism 14 are fixed to the mounting surfaces by bolts. The positioning pins are inserted into the pin holes to achieve precise positioning, ensuring that the transmitting end axis of the two noise reduction mechanisms is coaxial with the through hole of the housing. A shock-absorbing pad is provided between the mounting surface of the bracket and the outer wall of the housing.

[0043] Optionally, the first and second active noise cancellation mechanisms can be implemented using a combination of a moving-coil loudspeaker and a driving amplifier, mainly by generating sound waves that are inversely phase to the noise through the loudspeaker to cancel the noise.

[0044] For dynamic speakers, choose a 50W dynamic speaker, such as the TOA F-2352SC or JBL Control 25-1.

[0045] The driver amplifier incorporates a Class D amplifier module, such as a 50W Class D amplifier board based on the TI TPA3118 chip, or the BOSCHPLE-1MA050-EU. These components are symmetrically mounted on the second sensor bracket, with the speaker diaphragm facing the internal braking system. The amplifier receives the inverted signal output from the industrial control computer, driving the speaker to produce sound to cancel out noise.

[0046] In this embodiment, the U-shaped bracket utilizes the high strength of stainless steel to provide stable support. The positioning pin and the shock-absorbing pad work together to ensure the stability of the installation posture of the active noise reduction mechanism. The shock-absorbing pad reduces the impact of shell vibration on the noise reduction mechanism, ensuring stable noise reduction effect.

[0047] In some embodiments, both the first through hole 7 and the second through hole 13 are circular through holes, formed by CNC drilling. The hole diameter is 1.5 mm larger than the outer diameter of the transmitter end of the active noise cancellation mechanism. The hole walls are chamfered to remove burrs, and the surface roughness Ra ≤ 1.6 μm. The position of the through hole corresponds precisely to the mounting surface of the second sensor bracket 15, ensuring that after the active noise cancellation mechanism is installed, the distance between the transmitter end and the edge of the through hole is 2 mm. A silicone rubber gasket is embedded in the edge of the through hole. The inner diameter of the gasket is the same as that of the through hole, and the outer diameter is 5 mm larger than that of the through hole, fitting snugly against the transmitter end of the active noise cancellation mechanism.

[0048] As can be seen, the through-hole forms a sound wave conduction channel. The reverse sound wave emitted by the active noise cancellation mechanism enters the housing directly through the through-hole, superimposing with the original noise within the housing to achieve noise cancellation. The silicone rubber gasket seals the gap to prevent noise leakage, and the reverse sound wave reaches the noise source area directly through the through-hole, improving the noise cancellation efficiency.

[0049] The following are embodiments of the noise reduction method provided in this disclosure. This noise reduction method and the noise reduction device in the above embodiments belong to the same inventive concept. For details not described in detail in the embodiments of the noise reduction method, please refer to the embodiments of the noise reduction device described above.

[0050] The methods include: S101: The first end of the housing is connected to the generator via a connecting plate, wherein the connection contact surface between the connecting plate and the generator is provided with a first rubber medium; the second end of the housing is connected to the gearbox caliper and the high-speed shaft end face of the gearbox respectively, and the connection contact surface between the housing and the gearbox caliper is provided with a second rubber medium, and the connection contact surface between the housing and the high-speed shaft end face of the gearbox is provided with a third rubber medium.

[0051] S102: Install a first sensor bracket near the first end of the housing, and insert the sensing ends of the noise sensor and temperature sensor into the housing through the housing; install a second sensor bracket on the housing, and install a first active noise reduction mechanism and a second active noise reduction mechanism on the second sensor bracket; connect the noise sensor, the first active noise reduction mechanism and the second active noise reduction mechanism to the noise analyzer respectively, connect the noise analyzer to the industrial control computer, and connect the industrial control computer to the fan control system PLC.

[0052] S103: Set the sampling frequency of data acquisition to 2560Hz, and perform wavelet noise reduction preprocessing and spectral feature value analysis on the data acquired by the noise sensor through the industrial control computer.

[0053] S104: Set thresholds for sound pressure levels in different frequency bands. When the decibel value in any frequency band exceeds the threshold, control the first and second active noise reduction mechanisms to open to reduce noise from the sound source inside the casing, and feed back the decibel value signal to the fan control system PLC every 10 minutes.

[0054] S105: When the internal temperature of the housing collected by the temperature sensor exceeds the preset temperature threshold, the fan speed is reduced by the fan control system PLC, and the temperature signal is fed back to the fan control system PLC every 10 minutes.

[0055] S106: When the decibel value in all frequency bands is less than the threshold for 30 consecutive minutes, shut down the first active noise cancellation mechanism and the second active noise cancellation mechanism.

[0056] S107: When the internal temperature of the casing is lower than the preset temperature threshold for 30 consecutive minutes, the fan speed is restored to normal speed through the fan control system PLC.

[0057] In one embodiment of the present invention, based on step S103, the following is a possible embodiment and its specific implementation will be described in a non-limiting manner. S103 specifically includes the following steps: S1031: Configure the sampling parameters of the noise sensor through the data acquisition card, fix the sampling frequency to 2560Hz, and convert the analog noise signal into a digital signal sequence.

[0058] In some embodiments, the data acquisition card has a built-in analog-to-digital converter (ADC) that samples the voltage signal output by the noise sensor at a rate of 2560Hz to generate a digital sequence. The ADC resolution is set to bits, and the range matches the sensor output range.

[0059] S1032: The industrial control computer receives digital signal sequences through a serial communication interface and stores them as discrete-time signal data blocks in chronological order.

[0060] S1033: Perform discrete wavelet transform processing on the discrete-time signal data block, and use Daubechies wavelet basis functions for multi-scale decomposition to obtain wavelet coefficients at each level.

[0061] In some embodiments, the Daubechies4 wavelet is used as the basis function, and the filter coefficients are pre-stored in the industrial control computer's memory. Convolution and downsampling operations are performed on each data block to generate a tree-like coefficient structure. This decomposes the signal into sub-signals of different frequency bands, separating noise and useful components.

[0062] S1034: Based on the statistical characteristics of noise, a threshold is set, and soft threshold quantization is performed on the wavelet coefficients. Coefficients greater than the threshold are retained, and inverse discrete wavelet transform is performed on the quantized coefficients to reconstruct the denoised time domain signal.

[0063] In some embodiments, the detail coefficients of each layer are processed point-by-point while the approximation coefficients remain unchanged. The inverse transform is achieved through upsampling and convolution of the filter bank. In this way, noise-dominant wavelet coefficients are suppressed by thresholding, while signal-dominant coefficients are preserved, thereby removing noise during reconstruction.

[0064] S1035: Perform a fast Fourier transform on the denoised time-domain signal, calculate the frequency amplitude spectrum, divide the frequency bands into equal bandwidths, and calculate the sound pressure extreme values ​​in each frequency band as spectral characteristic values.

[0065] In some embodiments, the FFT has 1024 points and a frequency resolution of 2.5 Hz. Frequency bands are divided into 0-500 Hz, 500-1000 Hz, 1000-1500 Hz, 1500-2000 Hz, etc. The sound pressure level is obtained by taking the logarithm of the sum of the squares of the amplitudes of all frequencies within each band.

[0066] As can be seen, converting the time-domain signal into a frequency-domain energy distribution quantifies the noise intensity of each frequency band. This provides spectral characteristics, facilitating the setting of thresholds and the execution of frequency-selective noise reduction control.

[0067] In one embodiment of the present invention, based on step S104, the following is a possible embodiment and its specific implementation will be described in a non-limiting manner. S104 specifically includes the following steps: S1041: Based on the noise frequency characteristics of the wind turbine gearbox braking system during operation, the noise frequency range is segmented using equal bandwidth or variable bandwidth methods to determine the frequency interval boundaries of each frequency segment.

[0068] In some embodiments, based on the frequency distribution of vibration sources such as electromagnetic vibration and mechanical friction vibration during the operation of the gearbox braking system, an appropriate segmentation method is selected. Optionally, a 1 / 3 octave band division is adopted to clearly define the start and end frequencies of each frequency band, ensuring coverage of all noise frequency bands that need to be monitored.

[0069] S1042: Based on the noise sound pressure level fluctuation range and noise reduction target under normal operating conditions of the gearbox braking system, a sound pressure level threshold is set for each frequency band.

[0070] S1042 specifically includes the following steps: S10421: The wind turbine generator set is continuously operated under no-load, rated load and typical variable load conditions. The original noise time domain signal of the gearbox braking system during the stable operation period under each condition is collected by the installed noise sensor and industrial control computer data acquisition system and stored in the industrial control computer.

[0071] S10422: Call the preset signal processing program in the industrial control computer, and perform the same wavelet noise reduction preprocessing and fast Fourier transform operation as in step S103 on each segment of the original noise time domain signal stored in step S10421, and calculate the sound pressure level value of each segment of the signal in each preset frequency band.

[0072] S10423: For each preset frequency band, a sample dataset is compiled from all sound pressure level values ​​calculated under all operating conditions for that frequency band. Using the sample dataset, the arithmetic mean is calculated as the base sound pressure level for that frequency band, and its sample standard deviation is calculated as a measure of the fluctuation of that frequency band.

[0073] In some embodiments, for the first m The noise sound pressure level sample set is {Lp,i,m} for each frequency band.

[0074] Calculate the normal noise sound pressure level for this frequency band. and noise sound pressure level fluctuation .

[0075] Here, for each frequency band m Iterate through all sample values L p,i,m Calculate the mean of normal noise sound pressure level and the standard deviation of noise sound pressure level fluctuation.

[0076] This embodiment describes the gearbox braking system in the first... m The normal level and fluctuation of noise sound pressure level samples for each frequency band are estimated. The normal noise sound pressure level reflects the typical noise level of that frequency band, and the fluctuation of the noise sound pressure level reflects its normal range of variation, so that the threshold setting is based on the configuration of actual scenario data.

[0077] S10424: Consult the equipment technical manual to obtain the upper limit of the permissible continuous noise sound pressure level in the gearbox area, and use it as the global target sound pressure level L. target For each frequency band m, the arithmetic mean is calculated based on its statistical characteristics. and sample standard deviation And a margin coefficient k with a preset value range between 1.5 and 3.0 is used, through the formula Calculate the operating sound pressure level threshold for this frequency band. .

[0078] S10425: Calculate all frequency bands and their corresponding sound pressure level thresholds. It is stored in the industrial control computer in the form of key-value pairs.

[0079] S1043: The electrical signal output by the noise sensor is acquired in real time by the industrial control computer and converted into the sound pressure level value of the corresponding frequency band; In some embodiments, the analog electrical signal output by the noise sensor is amplified and filtered by the signal conditioning circuit, and then converted into a digital signal by the A / D conversion module of the industrial control computer. The digital signal is then converted into a sound pressure level value for the corresponding frequency band through a pre-stored frequency sound pressure level conversion relationship.

[0080] S1044: Compare the real-time sound pressure level values ​​of each frequency band with the corresponding thresholds set in S1042 one by one to determine whether there is a sound pressure level in a certain frequency band that exceeds the frequency band threshold.

[0081] S1045: When it is determined that the sound pressure level of any frequency band exceeds the threshold, an active noise reduction control command is generated and sent to the drive unit of the first active noise reduction mechanism and the second active noise reduction mechanism to drive the noise reduction mechanism to start; and at preset intervals, the current sound pressure level values ​​of each frequency band are packaged into signal frames and sent to the fan control system PLC.

[0082] In some embodiments, after receiving a control command, the active noise reduction mechanism generates an anti-phase sound wave that matches the noise frequency and amplitude according to the principle of inverse phase noise reduction. The drive unit receives the command through a relay or communication protocol and then executes the start operation. A data packaging function can be called every 10 minutes to convert the sound pressure level arrays of each frequency band into a message format conforming to the PLC communication protocol for transmission, thereby achieving precise control of noise in the gearbox braking system.

[0083] In one embodiment of the present invention, based on step S106, the following is a possible embodiment and its specific implementation will be described in a non-limiting manner. S106 specifically includes the following steps: S1061: The industrial control computer collects the decibel values ​​of each frequency band output by the noise sensor in real time, retrieves the sound pressure level threshold preset for each frequency band in S104, and compares the decibel value of each frequency band with the frequency band threshold one by one to confirm whether the decibel values ​​of all current frequency bands are less than the corresponding threshold.

[0084] In some embodiments, the decibel values ​​of each frequency band collected by the noise sensor are derived from the spectral feature value analysis results of S103. The correspondence between the frequency bands and thresholds set in S104 is pre-stored in the industrial control computer, and the comparison is performed one by one according to the frequency band order.

[0085] S1062: Set the monitoring period and record the comparison results in each period; if the decibel values ​​of all frequency bands are less than the threshold in a certain period, it is marked as meeting the requirements; if the decibel value of any frequency band exceeds the threshold, it is marked as not meeting the requirements.

[0086] S1063: Configure the timer module, initially set the cumulative time to 0; when a certain period is marked as meeting the requirements, the monitoring period duration is added to the cumulative time; when a certain period is marked as not meeting the requirements, the cumulative time is immediately reset to 0.

[0087] S1064: Check the accumulated time of the timer in real time. When the accumulated time reaches 30 minutes, generate a control command to turn off the active noise cancellation mechanism.

[0088] S1065: The control command is sent to the drive unit of the first active noise cancellation mechanism and the second active noise cancellation mechanism through the signal transmission line. The drive unit performs a shutdown operation to stop the sound source cancellation action of the active noise cancellation mechanism.

[0089] In some embodiments, the decibel values ​​of each frequency band are collected and compared with the threshold in real time, and the compliance status is marked periodically; a timer is used to accumulate the time required to meet the requirements and to reset the timer if the requirements are not met; a shutdown command is generated when the accumulated time reaches 30 minutes; a command is sent to drive the mechanism to shut down, ensuring that active noise reduction is turned off only after the noise inside the housing has stabilized and met the standard, so as to avoid premature shutdown and ineffective noise suppression.

[0090] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0091] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A noise reduction method, characterized in that, The method is used to perform noise reduction on the noise reduction device of the gearbox braking system of a wind turbine generator set; The noise reduction device of the wind turbine gearbox braking system includes: a housing (21), the first end of which is connected to the generator via a connecting plate (1); The connection contact surface between the connecting plate (1) and the generator is provided with a first rubber medium (2); One side of the second end of the housing (21) is connected to the gearbox caliper, and the contact surface of the connection is provided with a second rubber medium (3). The second end of the housing (21) is connected to the high-speed shaft end of the gearbox, and the contact surface of the connection is provided with a third rubber medium (4). The shell (21) is a hollow structure, and a gearbox braking system is installed inside the hollow structure; The hollow structure has a metal layer (11) embedded in its inner wall, and a sound-absorbing medium (10) is installed inside the metal layer (11); a sound-insulating medium (12) is installed outside the metal layer (11). A first sensor bracket (5) is installed near the first end of the housing (21); A noise sensor (9) and a temperature sensor (6) are mounted on the first sensor bracket (5). The sensing ends of the noise sensor (9) and the temperature sensor (6) extend into the housing (21) respectively to sense the noise and temperature information inside the housing. The methods include: S101: The first end of the housing is connected to the generator via a connecting plate, wherein the connection contact surface between the connecting plate and the generator is provided with a first rubber medium; the second end of the housing is connected to the gearbox caliper and the high-speed shaft end face of the gearbox respectively, and the connection contact surface between the housing and the gearbox caliper is provided with a second rubber medium, and the connection contact surface between the housing and the high-speed shaft end face of the gearbox is provided with a third rubber medium. S102: Install a first sensor bracket near the first end of the housing, and insert the sensing ends of the noise sensor and temperature sensor into the housing through the housing; install a second sensor bracket on the housing, and install a first active noise reduction mechanism and a second active noise reduction mechanism on the second sensor bracket; connect the noise sensor, the first active noise reduction mechanism and the second active noise reduction mechanism to the noise analyzer respectively, connect the noise analyzer to the industrial control computer, and connect the industrial control computer to the fan control system PLC; S103: Set the sampling frequency of data acquisition to 2560Hz, and perform wavelet noise reduction preprocessing and spectral feature value analysis on the data acquired by the noise sensor through the industrial control computer; S104: Set thresholds for sound pressure levels in different frequency bands. When the decibel value in any frequency band exceeds the threshold, control the first active noise reduction mechanism and the second active noise reduction mechanism to open to reduce noise from the sound source inside the casing, and feed back the decibel value signal to the fan control system PLC at preset intervals. S104 specifically includes the following steps: S1041: Based on the noise frequency characteristics of the wind turbine generator gearbox braking system during operation, the noise frequency range is segmented using equal bandwidth or variable bandwidth methods to determine the frequency interval boundaries of each frequency segment. S1042: Based on the noise pressure level fluctuation range and noise reduction target of the gearbox braking system under normal operating conditions, set a sound pressure level threshold for each frequency band. S1042 specifically includes the following steps: Under no-load, rated load and typical variable load conditions of wind turbine generator sets, the original noise time-domain signal of the gearbox braking system is collected by noise sensors and stored in the industrial control computer. The industrial control computer performs wavelet noise reduction preprocessing and fast Fourier transform on the stored raw noise time-domain signal to calculate the sound pressure level values ​​for each preset frequency band. For each preset frequency band, the mean normal noise sound pressure level and the standard deviation of noise sound pressure level fluctuation are calculated based on the sound pressure level values ​​of all operating conditions. Based on the upper limit of the allowable continuous noise sound pressure level in the gearbox area and the statistical characteristics of each frequency band, the operating sound pressure level threshold for each frequency band is calculated. Store each frequency band and its corresponding operating sound pressure level threshold in the industrial control computer in the form of key-value pairs; S1043: The electrical signal output by the noise sensor is acquired in real time by the industrial control computer and converted into the sound pressure level value of the corresponding frequency band; S1044: Compare the real-time sound pressure level values ​​of each frequency band with the corresponding thresholds set in S1042 one by one to determine whether there is a sound pressure level in a certain frequency band that exceeds the frequency band threshold. S1045: When it is determined that the sound pressure level of any frequency band exceeds the threshold, an active noise reduction control command is generated and sent to the drive unit of the first active noise reduction mechanism and the second active noise reduction mechanism to drive the noise reduction mechanism to start; and at preset intervals, the current sound pressure level values ​​of each frequency band are packaged into signal frames and sent to the fan control system PLC. S105: When the internal temperature of the housing collected by the temperature sensor exceeds the preset temperature threshold, the fan speed is reduced by the fan control system PLC, and the temperature signal is fed back to the fan control system PLC at preset intervals. S106: When the decibel value in all frequency bands is less than the threshold, shut down the first active noise cancellation mechanism and the second active noise cancellation mechanism. S107: When the internal temperature of the casing is lower than the preset temperature threshold, the fan speed is restored to the normal speed through the fan control system PLC.

2. The noise reduction method according to claim 1, characterized in that, The housing (21) has a first through hole (7) which is directly opposite the first active noise reduction mechanism (8).

3. The noise reduction method according to claim 1, characterized in that, A second through hole (13) is provided on the housing (21), and the second through hole (13) is directly opposite the second active noise reduction mechanism (14).

4. The noise reduction method according to claim 1, characterized in that, S103 specifically includes the following steps: Configure the sampling parameters of the noise sensor using a data acquisition card, fix the sampling frequency at 2560Hz, and convert the analog noise signal into a digital signal sequence. The industrial control computer receives digital signal sequences through a serial communication interface and stores them as discrete-time signal data blocks in chronological order. Discrete wavelet transform is performed on the discrete-time signal data block, and multi-scale decomposition is performed using Daubechies wavelet basis functions to obtain the wavelet coefficients of each level. Based on the statistical characteristics of noise, a threshold is set, and soft threshold quantization is performed on the wavelet coefficients. Coefficients greater than the threshold are retained, and inverse discrete wavelet transform is performed on the quantized coefficients to reconstruct the denoised time domain signal. Perform a fast Fourier transform on the denoised time-domain signal, calculate the frequency amplitude spectrum, divide the frequency bands into equal bandwidths, and calculate the sound pressure level value in each frequency band as the spectral characteristic value.

5. The noise reduction method according to claim 1, characterized in that, S106 specifically includes the following steps: The industrial control computer collects the decibel values ​​of each frequency band in real time and compares them with the preset sound pressure level threshold of the corresponding frequency band to determine whether the decibel values ​​of all frequency bands are less than the threshold. The industrial control computer records the comparison results in each monitoring cycle. If the decibel values ​​of all frequency bands are less than the threshold, it is marked as meeting the requirements; otherwise, it is marked as not meeting the requirements. The industrial control computer is equipped with a timer. When the monitoring cycle mark meets the requirements, the cumulative time is incremented; when the mark does not meet the requirements, the cumulative time is reset. The industrial control computer checks the cumulative time, and generates a control command to shut down the active noise cancellation mechanism when the cumulative time reaches 30 minutes. The industrial control computer sends control commands to the drive units of the first and second active noise cancellation mechanisms, and the drive units perform a shutdown operation to stop the sound source cancellation action.

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