A wind power gear box body modal test method

Abstract

The application provides a wind power gear box body modal test method, comprising the following steps: hoisting the wind power gear box on a test device, establishing a simulation model, performing free modal analysis, obtaining simulation values of each order elastic modal frequency, selecting a reference excitation point, determining an excitation value range, installing an acceleration sensor at the excitation point, knocking, receiving a sensing signal, processing the sensing signal to obtain a frequency domain signal, dividing the frequency domain signal into a first signal and a second signal according to peak values of the frequency domain signal, using the first signal to represent actual values of each order elastic modal frequency, calculating a relative error between a simulation value of each order elastic modal frequency and an actual value of the elastic modal frequency corresponding to the simulation value, taking an average value, and judging whether the average value is less than a first preset threshold value; if the average value is less than the first preset threshold value, the simulation model can be used to predict and optimize the performance of the wind power gear box.

Description

Technical Field

[0001] This application relates to the field of modal testing technology for wind turbine gearboxes, specifically to a modal testing method for wind turbine gearbox housings. Background Technology

[0002] Existing modal testing methods for wind turbine gearboxes typically require the construction of a modal testing platform. During operation, the gearbox is placed on the vibration testing platform, and different excitation methods are used to detect parameters such as the gearbox's natural frequencies, vibration modes, and structural response. However, existing signal processing methods suffer from several problems. Under different boundary conditions, it is difficult to distinguish between the rigid and elastic modes of the gearbox, leading to interference, errors, and aliasing. This makes it impossible to obtain accurate elastic and rigid mode frequency values ​​from the processed signals. Consequently, when assessing the finite element model and experimental errors, the discrepancy between simulation and experimental values ​​becomes significant. Therefore, it is impossible to accurately reflect the structural characteristics or performance of the gearbox that need to be measured, nor can the performance of the wind turbine gearbox be predicted and optimized. Summary of the Invention

[0003] The purpose of this application is to address the above problems by providing a modal testing method for wind turbine gearbox housings, the testing method comprising:

[0004] S1. Hoist the wind turbine gearbox onto the test device using the connectors;

[0005] S2. Establish a simulation model of the wind turbine gearbox, perform free modal analysis on the simulation model, obtain the simulation values ​​of each order of elastic modal frequencies of the wind turbine gearbox, and select a reference excitation point on the wind turbine gearbox to determine the range of excitation values.

[0006] S3. Install an acceleration sensor at the reference excitation point location;

[0007] S4. Excite the reference excitation point on the wind turbine gearbox with an excitation value within the range of the excitation value, and receive the sensing signal output by the acceleration sensor.

[0008] S5. Process the sensing signal to obtain a frequency domain signal. Based on the peak value of the frequency domain signal, decompose a first signal from the frequency domain signal. The first signal is used to represent the actual value of each elastic modal frequency in the frequency domain signal. Obtain the actual value of each elastic modal frequency from the first signal.

[0009] S6. Based on the simulated values ​​of each elastic modal frequency and the actual values ​​of each elastic modal frequency, calculate the relative error between the simulated value of each elastic modal frequency and its corresponding actual value, and take the average error value of each relative error. If the average error value is less than the first preset threshold, determine that the simulation model can be used to predict and optimize the performance of the wind turbine gearbox.

[0010] According to the technical solution provided in the embodiments of this application, after step S5 and before step S6, the following is further included:

[0011] A second signal is decomposed from the frequency domain signal. The second signal is used to represent the actual value of the rigid modal frequency in the frequency domain signal. The first elastic modal frequency is obtained from the first signal. When the rigid modal frequency is less than 20% of the first elastic modal frequency, the connector is determined to meet the free boundary condition.

[0012] According to the technical solution provided in the embodiments of this application, selecting the reference excitation point on the wind turbine gearbox specifically includes:

[0013] Obtain the actual dimensions of the wind turbine gearbox and establish the simulation model based on the actual dimensions;

[0014] The pitch line position of the risk gearbox is determined through the free modal analysis.

[0015] Avoiding the nodal line position, select an even number of reference excitation points on the wind turbine gearbox;

[0016] The positions of all the reference excitation points are symmetrically distributed relative to the nodal line positions.

[0017] According to the technical solution provided in the embodiments of this application, the step of determining the range of excitation values ​​specifically includes:

[0018] Determine the order of the required test elastic modal frequencies;

[0019] The order is input into the finite element software used to build the simulation model to obtain the value of the last elastic modal frequency.

[0020] The range of excitation values ​​is constructed by taking 0 as the minimum value and the value of the last elastic modal frequency as the maximum value.

[0021] According to the technical solution provided in the embodiments of this application, when the rigid modal frequency is greater than or equal to 20% of the first elastic modal frequency, the hardness of the current connector is obtained and recorded as the first hardness value.

[0022] Select a connector with a hardness lower than the first hardness value and repeat steps S1-S6 until it is determined that the first frequency domain signal is less than 20% of the first elastic modal frequency, at which point the connector is determined to meet the free boundary condition.

[0023] According to the technical solution provided in the embodiments of this application, after step S6, the following method is further included:

[0024] Obtain the mode shapes corresponding to the simulated frequencies of each elastic modal, and calculate the first mode shape;

[0025] Obtain the mode shapes corresponding to the actual values ​​of the elastic modal frequencies of each order, and calculate the second mode shape;

[0026] The first mode shape and the second mode shape are input into the modal confidence criterion evaluation formula to evaluate the reliability and accuracy of the first mode shape and the second mode shape.

[0027] According to the technical solution provided in the embodiments of this application, the test device includes: a support frame, on which two lifting components are provided, each of the lifting components having a first rotating shaft that can rotate around its own axis, and a steel wire rope is wound on the first rotating shaft;

[0028] At least two connectors, each of which is disposed on the wind turbine gearbox and arranged along a first direction, wherein the end of the connector that is relatively away from the wind turbine gearbox is connected to the wire rope.

[0029] According to the technical solution provided in the embodiments of this application, a slide rail extending in a first direction is provided on the support frame, a sliding component is provided on the slide rail, the sliding component is slidably connected to the slide rail, and the lifting component is provided on the sliding component.

[0030] According to the technical solution provided in the embodiments of this application, the sliding component includes the support platform, the bottom of the support platform is provided with a pulley, the pulley is slidably connected to the slide rail, and the pulley can rotate about its own axis relative to the support platform.

[0031] According to the technical solution provided in the embodiments of this application, a first through hole is provided on the support platform, and the steel wire rope passes through the first through hole and is connected to the connector.

[0032] Compared with the prior art, the beneficial effects of this application are as follows: This application obtains the simulated values ​​of the elastic modal frequencies of the wind turbine gearbox by suspending the wind turbine gearbox on a test device, establishing a simulation model of the wind turbine gearbox, and performing free modal analysis on it. Furthermore, a reference excitation point is selected on the wind turbine gearbox, and the range of excitation values ​​is determined. An accelerometer is installed at the reference excitation point, and the reference point is excited with an excitation value within the range of excitation values. The sensing signal output by the accelerometer is received, and then the sensing signal is processed to obtain a frequency domain signal. Based on the frequency domain signal... The peak value is decomposed into a first signal, which is used to represent the actual value of each elastic modal frequency in the frequency domain signal. The actual value of each elastic modal frequency is obtained from the first signal. Then, based on the simulated value of each elastic modal frequency and the actual value of each elastic modal frequency, the relative error between the simulated value of each elastic modal frequency and its corresponding actual value is calculated. The average error value of all relative errors is taken. Then, if the average error value is less than the first preset threshold, it is considered that the simulation model is relatively accurate and can be used to predict and optimize the performance of wind turbine gearboxes.

[0033] In the process of use, the wind turbine gearbox is first hoisted onto the test device, then a simulation model of the wind turbine gearbox is established, and free modal analysis is performed. Through free modal analysis, the simulated values ​​of each elastic modal frequency of the wind turbine gearbox can be obtained. A reference excitation point is selected on the wind turbine gearbox, and the range of excitation values ​​is determined. Then, an accelerometer is installed at the reference excitation point, and the reference excitation point is excited with values ​​within the excitation value range. The sensing signal output by the accelerometer is received, and then the received sensing signal is processed to obtain a frequency domain signal. The frequency domain signal has different peak values. Based on the peak values ​​of the frequency domain signal, the first signal is decomposed from the frequency domain signal, which is used to represent the actual value of each elastic modal frequency in the frequency domain signal. Then, based on the simulated value of each elastic modal frequency and its corresponding actual value, the relative error of each elastic modal frequency is calculated. Then, the average error value of all elastic modal frequencies is calculated, and the magnitude of the average error value is judged. When the average error value is less than the first preset threshold, it is indicated that the simulation model is relatively reliable and can be used to predict and optimize the performance of the wind turbine gearbox.

[0034] This application processes the acquired sensor signals to obtain frequency domain signals, and decomposes them according to the peak values ​​to derive a first signal representing the actual frequency domain values ​​of each order of elastic modes in the frequency domain signal. This allows for the differentiation between rigid and elastic modes of the gearbox, thus avoiding interference, errors, and aliasing in the first signal. The actual frequency values ​​of each order of elastic modes are then obtained from the first signal. The relative error between the simulated and actual values ​​of each order of elastic modes and their corresponding frequency domain simulated values ​​is calculated, and an average error value is obtained. This average error value is compared with a first preset threshold to determine the accuracy of the simulation model and its suitability for predicting and optimizing the performance of the wind turbine gearbox. Furthermore, this method can also determine the degree of free boundary conditions, obtaining more accurate free modal performance of the gearbox under freer boundary conditions. This provides the OEM with initial modal performance data for the gearbox, facilitating comparison with later gearbox failures and aiding in fault diagnosis and troubleshooting. It also helps determine the rationality of the gearbox installation location. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the overall structure of the wind turbine gearbox modal testing device provided in Embodiment 1 of this application;

[0036] Figure 2 Provided for Embodiment 1 of this application Figure 1 Enlarged view of point A in the middle;

[0037] Figure 3 Provided for Embodiment 1 of this application Figure 1 Enlarged view of point B in the middle;

[0038] Figure 4 Provided for Embodiment 1 of this application Figure 1 Enlarged view of point C in the middle;

[0039] Figure 5 This is a flowchart of the method provided in Embodiment 1 of this application;

[0040] Figure 6 This is the fourth set of MAC matrix results provided in Embodiment 1 of this application;

[0041] Figure 7 This is a schematic diagram of the structure of the rolling wheel assembly provided in Embodiment 1 of this application;

[0042] Figure 8 This is a schematic diagram of the roller mounting bracket and roller provided in Embodiment 1 of this application.

[0043] The text labels in the diagram represent: 1. Wind turbine gearbox; 2. Support frame; 3. Lifting component; 4. Connector; 5. First rotating shaft; 6. Wire rope; 7. Slide rail; 8. Support platform; 9. Pulley; 11. Hook; 12. Ear hole; 13. Rotary drive motor; 14. Lifting drive motor; 15. First mounting part; 16. Bearing part; 17. First shielding part; 18. Second shielding part; 20. Rolling wheel; 21. Rolling wheel rotating shaft; 22. Bolt; 23. Spring; 24. Rolling wheel mounting bracket. Detailed Implementation

[0044] To enable those skilled in the art to better understand the technical solution of this application, the application will be described in detail below with reference to the accompanying drawings. The description in this section is only exemplary and explanatory, and should not be used to limit the scope of protection of this application.

[0045] This application provides a modal testing device for a wind turbine gearbox housing. The testing device includes a wind turbine gearbox 1 and further includes:

[0046] Support frame 2, the support frame 2 is provided with at least two lifting components 3, each of the lifting components 3 has a first rotating shaft 5 that can rotate around its own axis, and a steel wire rope 6 is wound on the first rotating shaft 5;

[0047] At least two connectors 4 are provided on the wind turbine gearbox 1 and arranged along a first direction. The end of the connector 4 that is relatively away from the wind turbine gearbox 1 is connected to the wire rope 6.

[0048] Specifically, in this embodiment, please refer to Figure 1The support frame 2 includes a first support portion extending along a first direction, and a second support portion and a third support portion connected to both ends of the first support portion and perpendicular to the first support portion. The second support portion and the third support portion extend along a second direction and are arranged sequentially along the first direction, with the second direction being perpendicular to the first direction. A hoisting component 3 is provided on the first support portion, with at least two hoisting components 3 arranged along the first direction. The hoisting component 3 is a winch, and the winch has a first rotating shaft 5. A lifting drive motor 14 is also provided on the second support portion, and the lifting drive motor 14 has a lifting drive end connected to the first rotating shaft 5. The lifting drive end is used to drive the first rotating shaft 5 to rotate around its own axis. A steel wire rope 6 is wound on the first rotating shaft 5. Through the lifting drive motor 14, the steel wire rope 6 can be correspondingly unwound or wound. At least two connecting components 4 are provided on the wind turbine gearbox 1. All connecting parts 4 are mounted on the wind turbine gearbox 1. The specific connecting parts 4 used in this embodiment need continuous verification to determine if they meet the free boundary conditions. First, a steel wire rope 6 is used as the connecting part 4. If the steel wire rope 6 does not meet the free boundary conditions, then a nylon rope is used as the connecting part 4, and the free boundary conditions are again determined. If not, a rubber rope is used for verification until the free boundary conditions are met. When determining whether the free boundary conditions are met, the rigid frequency picked up from the test results can be used. Under ideal free modal conditions, the rigid body frequency of the wind turbine gearbox 1 is 0. The rigid body frequency of the model cannot be captured during the test. If the rigid modal frequency in the test results is close to 0, and the maximum value does not exceed 20% of the first-order elastic modal frequency, then the free boundary conditions are met. This will be explained in detail in the following method section. The end of the connecting part 4 that is relatively far from the wind turbine gearbox 1 is connected to the steel wire rope 6.A roller assembly is also provided at the bottom end of the support frame 2. This roller assembly allows for the movement of the entire device. The roller assembly includes roller mounting brackets 24 connected to the bottom ends of the four support legs of the support frame 2. The roller mounting brackets 24 have a rotation space inside, within which rollers 20 are mounted. A roller rotation shaft 21 is provided along the axial direction of the rollers 20. Circular mounting slots are respectively provided on opposite sides of the roller mounting brackets 24, and bearings are installed in these slots. The two ends of the roller rotation shaft 21 are respectively... The roller 20 is located in the two circular mounting slots and can rotate around the roller rotation axis 21. To prevent the entire device from moving during the test, a clamping member is also provided on the roller mounting bracket 24. The clamping member includes a threaded rod extending in the horizontal direction, and a spring 23 is provided on the threaded rod. A bolt 22 is provided at one end of the threaded rod. By rotating the bolt 22, the spring 23 can be compressed. The other end of the clamping member forms a clamping space, which has a clamping end located in the rotating hole space and on the outside of the wheel, such as; Figure 7 and Figure 8 As shown, when the bolt 22 is rotated, the clamping ends will also move closer to each other, thereby clamping the rolling wheel 20 and preventing the rolling wheel 20 from rotating. Its working principle is the same as that of pliers. When the two pliers handles move closer to each other, the other ends of the pliers will also move closer to each other, thereby clamping the object to be clamped.

[0049] During use, the support frame 2 is first moved above the wind turbine gearbox 1, and then the lifting drive motor 14 is started. The lifting drive motor 14 drives the first rotating shaft 5 to rotate, so that the wire rope 6 wound on the first rotating shaft 5 is released until the end of the wire rope 6 away from the winch can be hooked together with the connector 4. Then the lifting drive motor 14 is reversed so that the wire rope 6 is wound on the first rotating shaft 5, thereby lifting the wind turbine gearbox 1 and suspending it in the air. Then the connector 4 is replaced, and it is determined whether the suspended wind turbine gearbox 1 can meet the free boundary conditions. If it does not meet the conditions, the connector 4 is replaced again until it is determined that the suspended wind turbine gearbox 1 can meet the free boundary conditions. For specific judgment conditions, please refer to the embodiments in the method section.

[0050] This application, by providing a support frame 2 and a hoisting component 3 on the support frame 2, can realize the free boundary conditions of the wind turbine gearbox 1, reduce the difference between the actual measured modal frequencies and the actual situation, reduce the distortion of modal shapes, and also reduce the modal coupling effect.

[0051] Furthermore, a slide rail 7 extending along a first direction is provided on the support frame 2, and a sliding component is provided on the slide rail 7. The sliding component is slidably connected to the slide rail 7, and the lifting component 3 is provided on the sliding component.

[0052] Specifically, in this embodiment, a slide rail 7 extending along the first direction is provided on the upper surface of the support frame 2, and a sliding component is provided on the slide rail 7. The sliding component is slidably connected to the slide rail 7, and the sliding component can move along the extension direction of the slide rail 7. The lifting component 3 is provided on the sliding component.

[0053] During use, the lifting drive motor 14 is used to release the wire rope 6 wound on the first rotating shaft 5. The other end of the wire rope 6 is placed above the connector 4 of the wind turbine gearbox 1. Then, the sliding component slides on the slide rail 7, causing the hoisting component 3 to slide on the slide rail 7 until the end of the wire rope 6 away from the hoisting component 3 is observed to be directly above the connector 4. Then, the wire rope 6 is connected to the connector 4. Then, the lifting drive motor 14 is used to retract the wire rope 6. As the wire rope 6 is retracted, the wind turbine gearbox 1 will also be suspended on the support frame 2. Then, the free boundary conditions of the wind turbine gearbox 1 are tested to see if they meet the requirements.

[0054] Furthermore, the sliding component includes the support platform 8, the bottom of the support platform 8 is provided with a pulley 9, the pulley 9 is slidably connected to the slide rail 7, and the pulley 9 can rotate about its own axis relative to the support platform 8.

[0055] Furthermore, the number of slide rails 7 is two, and the two slide rails 7 are arranged along a second direction, which is perpendicular to the first direction.

[0056] Specifically, in this embodiment, please refer to Figure 2 There are two slide rails 7, and the two slide rails 7 are arranged sequentially along the second direction. The sliding assembly includes a support platform 8, which is cuboid in shape. Four first mounting parts 15 are provided at the four corners of the bottom of the support platform 8. Each first mounting part 15 has a rotation space. A pulley 9 is installed in each rotation space. There are four pulleys 9 in total, divided into two groups. Each group of pulleys 9 is located on each slide rail 7, and the pulleys 9 on each slide rail 7 are arranged along the extension direction of the slide rail 7. A rotary drive motor 13 is also provided on the support platform 8. The rotary drive motor 13 has a rotary drive shaft, which is connected to the rotation shaft of one of the pulleys 9 to drive the pulley 9 to move along the first direction on the slide rail 7.

[0057] Furthermore, a first through hole is provided on the support platform 8, through which the steel wire rope 6 passes and connects to the connector 4.

[0058] Specifically, in this embodiment, a first through hole is provided on the support platform 8. The first through hole provides space for the steel wire rope 6 to pass through and connect with the wind turbine gearbox 1. The diameter of the first through hole is slightly larger than the diameter of the steel wire rope 6, which can ensure that the steel wire rope 6 can pass through smoothly.

[0059] Furthermore, a hook is provided between the wire rope 6 and the connector 4.

[0060] Specifically, in this embodiment, a hook is also provided between the wire rope 6 and the connector 4, and the shape of the hook is as follows: Figure 3 As shown, the hook includes a support portion 16 connected to the wire rope 6, and a hook portion 11 for hooking the connector 4. It also includes a first shielding portion 17 and a second shielding portion 18. The support portion 16 is located between the first shielding portion 17 and the second shielding portion 18. The support portion 16 is cylindrical. The hook portion 11 is fixedly connected to the first shielding portion 17 and the second shielding portion 18. An ear hole 12 is also provided between the connector 4 and the wind turbine gearbox 1. Figure 4 As shown, the ear hole 12 is used to provide a connection point for the connector 14. In use, the connector 14 can pass directly through the ear hole 12 and be fixed on the wind turbine gearbox 1.

[0061] In addition to the aforementioned experimental apparatus, the entire experimental setup also includes a signal acquisition and processing device. Specifically, a table is placed on the ground, and a computer (similar to a workstation) is placed on the table. A signal acquisition front-end is also placed on the table. The signal acquisition front-end is connected to two sensors. One sensor is connected to a triaxial acceleration sensor, which is attached to the surface of the wind turbine gearbox. The other sensor is connected to a force sensor, which is used to apply excitation to the wind turbine gearbox. After the two sensors have acquired their respective signals, the acquired signals are input into the signal acquisition front-end. After processing by the signal acquisition front-end, the signals can be input into the computer for viewing.

[0062] The test method described in this application embodiment is based on a test apparatus, and the test method includes:

[0063] S1. Hoist the wind turbine gearbox onto the test device using the connectors;

[0064] S2. Establish a simulation model of the wind turbine gearbox, perform free modal analysis on the simulation model, obtain the simulation values ​​of each order of elastic modal frequencies of the wind turbine gearbox, and select a reference excitation point on the wind turbine gearbox to determine the range of excitation values.

[0065] B. Selecting the reference excitation point on the wind turbine gearbox specifically includes:

[0066] Obtain the actual dimensions of the wind turbine gearbox and establish the simulation model based on the actual dimensions;

[0067] The pitch line position of the risk gearbox is determined through the free modal analysis.

[0068] Avoiding the nodal line position, select an even number of reference excitation points on the wind turbine gearbox;

[0069] The positions of all the reference excitation points are symmetrically distributed relative to the nodal line positions.

[0070] C. The step of determining the range of the excitation value specifically includes:

[0071] Determine the order of the required test elastic modal frequencies;

[0072] The order is input into the finite element software used to build the simulation model to obtain the value of the last elastic modal frequency.

[0073] The range of excitation values ​​is constructed by taking 0 as the minimum value and the value of the last elastic modal frequency as the maximum value.

[0074] Specifically, in this embodiment, the actual dimensions of the wind turbine gearbox, including its length, width, and height, must first be measured. These dimensions are then input into the finite element method (FEM) software used to build the simulation model. A simulation model is established, and free modal analysis is performed on the gearbox to determine the location of the pitch line. Since this part will not produce corresponding vibrations even when excited, the pitch line location needs to be selected to avoid mode loss. Then, avoiding the pitch line location, an even number of reference excitation points are selected on the gearbox, symmetrically distributed relative to the pitch line location. After confirming the reference excitation points, the range of excitation values ​​needs to be determined. When determining the excitation value range, the order of the elastic modal frequencies to be tested must first be determined. Assuming that only the first ten frequencies are desired in the experiment, the tenth frequency can be obtained through free modal simulation in the finite element method software. The frequency corresponding to the tenth order becomes the maximum value of the excitation value, and the minimum value is 0. That is to say, the maximum value of the excitation value is the frequency value corresponding to a certain elastic modal frequency. Therefore, the range of the desired frequency is [0, the frequency corresponding to the tenth order]. When conducting modal tests, the excitation value range should theoretically be selected based on the frequency of the order of interest. In practice, a value slightly larger than that frequency value should be selected to avoid experimental errors causing the measured frequency to be too large, thus failing to capture that order of mode. After the above steps are completed, an experimental model needs to be established. The establishment of the experimental model involves connecting the determined reference excitation points with points, lines, and surfaces to form the experimental model. The experimental model is used to characterize the mode shape animation of the actual object. Through the subsequent mode shape animation, the mode shape and shape of the wind turbine gearbox can be obtained. The mode shape animation can be compared with the mode shape simulation of the finite element model to determine the accuracy of the finite element model.

[0075] S3. Install an acceleration sensor at the reference excitation point location;

[0076] Specifically, in this embodiment, an acceleration sensor is installed at the location of each reference excitation point. For example, to prevent the acceleration sensor from falling off during the test, it can be installed on the wind turbine gearbox by pasting or other means.

[0077] S4. Excite the reference excitation point on the wind turbine gearbox with an excitation value within the range of the excitation value, and receive the sensing signal output by the acceleration sensor.

[0078] Specifically, in this embodiment, the reference excitation point on the wind turbine gearbox needs to be excited within the excitation value range, and then the sensing signal output by the acceleration sensor is received. Before excitation, the excitation method of the wind turbine gearbox needs to be selected. The excitation methods include hammer excitation and vibrator excitation. In this embodiment, the excitation method of the wind turbine gearbox is hammer excitation. Hammer excitation is divided into single reference impact testing (MRIT) and multiple reference impact testing (MRIT). Since the test object is a large structure, the multiple reference impact testing technology, which is easy to install and highly mobile, is used for testing. The multiple reference impact testing technology can provide a more comprehensive and accurate vibration response of the wind turbine gearbox. Compared to single-reference-point impact testing, multi-reference-point impact testing can acquire more data in a single test, reducing testing time and cost. This is particularly important for testing large structures or complex systems. During excitation, an accelerometer is used to excite the wind turbine gearbox. In this embodiment, an ICP piezoelectric sensor is selected. After the wind turbine gearbox is excited at high frequency using a hammer, the accelerometer transmits the vibration acceleration signal to the data acquisition front end through the principle of "piezoelectric effect." At the same time, the force sensor on the hammer also transmits a signal to the data acquisition front end. By performing a fast Fourier transform on the time-domain signal, the frequency response function (FRF) of the wind turbine gearbox structure is obtained. This function can be used to describe the vibration characteristics and dynamic response of the gearbox structure at different frequencies, and it can also be used to evaluate the stability of the gearbox structure.

[0079] S5. Process the sensing signal to obtain a frequency domain signal. Based on the peak value of the frequency domain signal, decompose a first signal from the frequency domain signal. The first signal is used to represent the actual value of each elastic modal frequency in the frequency domain signal. Obtain the actual value of each elastic modal frequency from the first signal.

[0080] Specifically, in this embodiment, after processing the sensor, a frequency domain signal is obtained. The frequency domain signal has multiple peaks. Based on the peaks of the frequency domain signal, a first signal is decomposed from the frequency domain signal. The first signal is used to represent the actual value of each elastic modal frequency in the frequency domain signal. The actual value of each elastic modal frequency can be obtained directly from the first signal.

[0081] S6. Based on the simulated values ​​of each elastic modal frequency and the actual values ​​of each elastic modal frequency, calculate the relative error between the simulated value of each elastic modal frequency and its corresponding actual value, and take the average error value of each relative error. If the average error value is less than the first preset threshold, determine that the simulation model can be used to predict and optimize the performance of the wind turbine gearbox.

[0082] D. Obtain the mode shapes corresponding to the simulated frequencies of each elastic modal, and calculate the first mode shape;

[0083] Obtain the mode shapes corresponding to the actual values ​​of the elastic modal frequencies of each order, and calculate the second mode shape;

[0084] The first and second vibration modes are input into the modal confidence criterion evaluation formula to evaluate the reliability and accuracy of the elastic modal frequencies of each order.

[0085] Specifically, in this embodiment, the wind turbine gearbox is first hoisted onto the test device using connectors. After hoisting, the simulated values ​​and actual values ​​of each elastic modal frequency are obtained. Then, the relative error between the simulated value and the corresponding actual value of each elastic modal frequency is calculated. For example, the first relative error between the simulated value and the actual value of the first elastic modal frequency is calculated, and the second relative error between the simulated value and the actual value of the second elastic modal frequency is calculated. Finally, all relative errors are calculated. The average error value (the average of the first-order relative error and the second-order relative error) is calculated as follows: Xth relative error = (Xth order elastic modal frequency simulation value - Xth order elastic modal frequency actual value) / Xth order elastic modal frequency simulation value. Then, the average error value is calculated, and then it is determined whether the average error value is less than a first preset threshold. In this embodiment, the first preset threshold is 10%. When it is determined that the average error value is less than the first preset threshold of 10%, it indicates that the simulation model can truly reflect the performance of the wind turbine gearbox and can be used to predict and optimize the performance of the wind turbine gearbox.

[0086] To avoid extracting interfering modes from the experimental results that are not inherent to the wind turbine gearbox structure itself, the mode shapes corresponding to the simulated values ​​of each elastic modal frequency are obtained, and summed to obtain the first mode shape. The mode shapes corresponding to the actual values ​​of each elastic modal frequency are also obtained, and summed to obtain the second mode shape. The first and second mode shapes are then input into the Model Assurance Criterion (MAC) to evaluate the accuracy and reliability of each elastic modal frequency. MAC is a crucial criterion for evaluating the correlation of mode shapes. The expression for calculating MAC is:

[0087]

[0088] In the above formula, ФA represents the vector of the first mode shape;

[0089] ФB represents the vector of the second mode shape;

[0090] The scalar value obtained from MAC calculation is between 0 and 1, or expressed as a percentage. The smaller the MAC value, the weaker the correlation between the vectors of the first mode and the second mode, and the stronger their orthogonality. The larger the MAC value, the more parallel or similar the vectors of the first mode and the second mode are to each other, indicating that the experimental results are more accurate in identifying the actual frequency and mode shape. In an ideal MAC matrix, apart from the main diagonal elements (which represent the correlation between each mode and itself, usually 1), the other element values ​​(representing the correlation between different modes, usually ranging from -1 to 1, where -1 represents a completely negative correlation, 1 represents a completely positive correlation, and 0 represents no correlation) are very small. At this time, the mode shapes are independent of each other.

[0091] like Figure 6 As shown, the MAC matrix results of the fourth group of the wind turbine gearbox modal test are presented. The main diagonal elements are the dot products of the first four elastic modes themselves, which are close to 1, indicating that the correlation between each mode and itself is stronger. The off-diagonal elements are close to 0, indicating no correlation. This means that the mode shapes are independent of each other, the position and number of modal reference points are reasonable, and there are no spurious modes in the test results.

[0092] If the mode shape matrix of an object Then the first mode vector Second mode vector The dot product of the first mode shape vector itself (Main diagonal elements), the dot product of the first mode vector and the second mode vector (Other elements)

[0093] Furthermore, the procedure includes the following steps after step S5 and before step S6:

[0094] A third signal is decomposed from the frequency domain signal. The third signal is used to represent the actual value of the rigid modal frequency in the frequency domain signal. The first elastic modal frequency is obtained from the first signal. When the rigid modal frequency is less than 20% of the first elastic modal frequency, the connector is determined to meet the free boundary condition.

[0095] When the rigid modal frequency is determined to be greater than or equal to 20% of the first elastic modal frequency, the hardness of the current connector is obtained and recorded as the first hardness value.

[0096] Select a connector with a hardness lower than the first hardness value and repeat steps S1-S6 until it is determined that the first frequency domain signal is less than 20% of the first elastic modal frequency, at which point the connector is determined to meet the free boundary condition.

[0097] Specifically, in this embodiment, it is necessary to determine whether the connector meets the free boundary condition. Therefore, it is necessary to decompose the third signal from the frequency domain signal. The third signal is used to represent the actual value of the rigid mode frequency in the frequency domain signal. When it is determined that the rigid mode frequency is less than 20% of the first elastic mode frequency, it can be concluded that the connector meets the free boundary condition.

[0098] When it is determined that the rigid modal frequency is greater than or equal to 20% of the first elastic modal frequency, the hardness of the current connector is obtained and recorded as the first hardness value.

[0099] Select a connector with a hardness lower than the first value and repeat steps S1-S6 until it is determined that the first frequency domain signal is less than 20% of the first elastic mode frequency. Then, it is determined that the connector meets the free boundary conditions. Only when the boundary conditions meet the requirements can the wind turbine gearbox be formally tested. If the boundary conditions do not meet the requirements, the connector needs to be replaced until it is determined that the boundary conditions meet the requirements.

[0100] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. The above descriptions are only preferred embodiments of this application. It should be noted that due to the limitations of written expression, while there are objectively infinite specific structures, those skilled in the art can make several improvements, modifications, or changes without departing from the principles of this invention, and can also combine the above technical features in an appropriate manner. These improvements, modifications, changes, or combinations, or the direct application of the inventive concept and technical solution to other situations without modification, should all be considered within the scope of protection of this application.

Claims

1. A wind turbine gearbox case modal test method, characterized in that, include: S1. Hoist the wind turbine gearbox onto the test device using the connectors; S2. Establish a simulation model of the wind turbine gearbox, perform free modal analysis on the simulation model, obtain the simulation values ​​of each order of elastic modal frequencies of the wind turbine gearbox, and select a reference excitation point on the wind turbine gearbox to determine the range of excitation values. S3. Install an acceleration sensor at the reference excitation point location; S4. Excite the reference excitation point on the wind turbine gearbox with an excitation value within the range of the excitation value, and receive the sensing signal output by the acceleration sensor. S5. Process the sensing signal to obtain a frequency domain signal. Based on the peak value of the frequency domain signal, decompose a first signal from the frequency domain signal. The first signal is used to represent the actual value of each elastic modal frequency in the frequency domain signal. Obtain the actual value of each elastic modal frequency from the first signal. A second signal is decomposed from the frequency domain signal. The second signal is used to represent the actual value of the rigid modal frequency in the frequency domain signal. The first elastic modal frequency is obtained from the first frequency domain signal. When the rigid modal frequency is less than 20% of the first elastic modal frequency, the connector is determined to meet the free boundary condition. S6. Based on the simulated values ​​of each elastic modal frequency and the actual values ​​of each elastic modal frequency, calculate the relative error between the simulated value of each elastic modal frequency and its corresponding actual value, and take the average error value of each relative error. If the average error value is less than the first preset threshold, determine that the simulation model is used to predict and optimize the performance of the wind turbine gearbox. Obtain the mode shapes corresponding to the simulated frequencies of each elastic modal, and calculate the first mode shape; Obtain the mode shapes corresponding to the actual values ​​of the elastic modal frequencies of each order, and calculate the second mode shape; The first and second vibration modes are input into the modal confidence criterion evaluation formula to evaluate the reliability and accuracy of the elastic modal frequencies of each order.

2. The wind turbine gearbox case modal test method according to claim 1, characterized in that, The selection of the reference excitation point on the wind turbine gearbox specifically includes: Obtain the actual dimensions of the wind turbine gearbox and establish the simulation model based on the actual dimensions; The nodal line position of the wind turbine gearbox is determined through the free modal analysis. Avoiding the nodal line position, select an even number of reference excitation points on the wind turbine gearbox; The positions of all the reference excitation points are symmetrically distributed relative to the nodal line positions.

3. The wind turbine gearbox case modal test method according to claim 2, characterized in that, The step of determining the range of the excitation value specifically includes: Determine the order of the required test elastic modal frequencies; The order is input into the finite element software used to build the simulation model to obtain the value of the last elastic modal frequency. The range of excitation values ​​is constructed by taking 0 as the minimum value and the value of the last elastic modal frequency as the maximum value.

4. The modal testing method for wind turbine gearbox housing according to claim 3, characterized in that, When the rigid modal frequency is determined to be greater than or equal to 20% of the first elastic modal frequency, the hardness of the current connector is obtained and recorded as the first hardness value. Select a connector with a hardness lower than the first hardness value and repeat steps S1-S6 until it is determined that the first frequency domain signal is less than 20% of the first elastic modal frequency, at which point the connector is determined to meet the free boundary condition.

5. The modal test method for wind turbine gearbox housing according to claim 1, characterized in that, The test apparatus includes: A support frame (2) is provided with at least two lifting components (3), each of the lifting components (3) having a first rotating shaft (5) that rotates about its own axis, and a steel wire rope (6) is wound on the first rotating shaft (5). At least two connectors (4), each of the connectors (4) is provided on the wind turbine gearbox (1) and arranged along a first direction, and the end of the connector (4) that is relatively away from the wind turbine gearbox (1) is connected to the wire rope (6).

6. The modal testing method for wind turbine gearbox housing according to claim 5, characterized in that, A slide rail (7) extending in a first direction is provided on the support frame (2), and a sliding component is provided on the slide rail (7). The sliding component is slidably connected to the slide rail (7), and the lifting component (3) is provided on the sliding component.

7. The modal testing method for wind turbine gearbox housing according to claim 6, characterized in that, The sliding assembly includes a support platform (8), and a pulley (9) is provided at the bottom of the support platform (8). The pulley (9) is slidably connected to the slide rail (7), and the pulley (9) rotates about its own axis relative to the support platform (8).

8. The modal test method for wind turbine gearbox housing according to claim 7, characterized in that, A first through hole is provided on the support platform (8), and the wire rope (6) passes through the first through hole and is connected to the connector (4).

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