Wind turbine generator rotating shaft fault monitoring method and system based on pulse amplitude modulation

Abstract

The invention provides a wind turbine generator rotating shaft fault monitoring method and system based on pulse amplitude modulation. The method comprises the steps that pulse amplitude modulation signals of a rotating shaft are collected through a pulse amplitude modulation measuring device installed on a target shaft section of the rotating shaft of a measured wind turbine generator; performing amplitude demodulation on the pulse amplitude modulation signal to obtain an eccentric compound vibration component of the rotating shaft; carrying out discretization processing to obtain a composite vibration component sequence of a discrete time domain, then carrying out Fourier transform on the sequence of the discrete time domain to obtain phase differences, and extracting vibration amplitudes and amplitude characteristic parameters of each vibration component under different frequencies; and monitoring a misalignment abnormal state of the rotating shaft according to the vibration amplitudes, the amplitude characteristic parameters and the phase differences of the vibration components under different frequencies. According to the technical scheme, signals are collected through the pulse amplitude modulation measuring device, and high-precision monitoring and accurate fault type identification of the misalignment of the rotating shaft of the wind turbine generator are realized in combination with amplitude demodulation and frequency domain analysis.

Description

Technical Field

[0001] This application relates to the field of pulse amplitude modulation technology, and in particular to a method and system for monitoring wind turbine shaft faults based on pulse amplitude modulation. Background Technology

[0002] As a core component of new energy power generation, the operational stability of the wind turbine's shaft system directly determines the unit's power generation efficiency and service life. During the manufacturing, installation, and long-term operation of wind turbines, factors such as component machining errors, assembly deviations, foundation settlement, or shaft wear can cause the shaft to deviate from its theoretical rotation center, resulting in misalignment faults (such as parallel misalignment or angular misalignment). When misalignment occurs, periodic vibration components are generated during operation. On the one hand, this vibration exacerbates the wear of critical components such as bearings and gears, shortening the equipment's lifespan. On the other hand, if not monitored and addressed in a timely manner, it may lead to serious accidents such as shaft jamming or breakage, causing significant economic losses. Therefore, a high-precision and highly adaptable method for monitoring wind turbine shaft misalignment is urgently needed.

[0003] Existing technologies suffer from several drawbacks: low signal extraction accuracy, traditional monitoring relies heavily on accelerometers to collect vibration signals, but the complex operating environment of wind turbines (including airflow disturbances and electromagnetic interference) easily leads to low signal-to-noise ratios, making it difficult to accurately extract vibration characteristics corresponding to misalignment; and poor adaptability to variable speeds, as wind turbines often operate at varying speeds (affected by wind speed changes). Traditional methods struggle to distinguish between signal changes caused by speed fluctuations and vibration signals caused by misalignment, resulting in significant monitoring errors. Therefore, there is an urgent need for a solution that can perform high-precision monitoring and fault type identification for wind turbine shaft misalignment. Summary of the Invention

[0004] This application provides a method and system for monitoring wind turbine shaft faults based on pulse amplitude modulation, so as to at least solve the technical problems of low monitoring accuracy and inaccurate identification of fault types.

[0005] The first aspect of this application proposes a method for monitoring wind turbine shaft faults based on pulse amplitude modulation, the method comprising:

[0006] The pulse amplitude modulation signal of the wind turbine shaft is acquired by a pulse amplitude modulation measurement device installed on the target shaft section of the wind turbine shaft under test. The pulse amplitude modulation signal is generated by the displacement sensor sensing the change in the groove height difference of the grooved tooth disk and the distance change caused by the shaft eccentricity.

[0007] The amplitude of the pulse amplitude-modulated signal is demodulated to obtain the eccentric composite vibration component of the rotating shaft;

[0008] The eccentric composite vibration components are discretized to obtain a discrete-time composite vibration component sequence. Then, the discrete-time composite vibration component sequence is subjected to Fourier transform to obtain each phase difference, and the vibration amplitude and amplitude characteristic parameters of each vibration component at different frequencies are extracted.

[0009] The misalignment anomaly of the rotating shaft is monitored based on the vibration amplitude, amplitude characteristic parameters, and phase difference of each vibration component at different frequencies.

[0010] Preferably, the pulse amplitude modulation measuring device includes: a slotted toothed disc and a displacement sensor.

[0011] Furthermore, the step of demodulating the amplitude of the pulse amplitude-modulated signal to obtain the eccentric vibration component of the rotating shaft includes:

[0012] The amplitude envelope of the pulse amplitude-modulated signal is extracted by filtering or envelope detection methods.

[0013] The amplitude envelope is converted into the eccentric vibration component of the rotating shaft based on the sensitivity parameters and bias voltage of the displacement sensor.

[0014] Furthermore, the step of performing a Fourier transform on the discrete-time composite vibration component sequence to obtain each phase difference, and extracting the vibration amplitude and amplitude characteristic parameters of each vibration component at different frequencies, includes:

[0015] The frequency domain signal of the eccentric composite vibration component is obtained by performing a Fourier transform on the discrete time domain composite vibration component sequence.

[0016] Based on the frequency domain signal, the vibration amplitude and amplitude characteristic parameters of each vibration component at different frequencies are extracted;

[0017] The Fourier series corresponding to the discrete-time composite vibration component sequence is decomposed using Euler's formula to obtain the coefficients of the Fourier series. The initial phase angle of each vibration component is determined based on the coefficients of the Fourier series, and then the phase difference is determined based on the initial phase angle of each vibration component.

[0018] Furthermore, the monitoring of the misalignment anomaly of the rotating shaft based on the vibration amplitude, amplitude characteristic parameters, and phase difference of each vibration component at different frequencies includes:

[0019] Based on the vibration amplitude of each vibration component at different frequencies, determine the ratio of the vibration amplitude of each vibration component at a+1 times the frequency to the vibration amplitude at a times the frequency.

[0020] When the ratio corresponding to the i-th vibration component is greater than the first threshold and the j-th phase difference is 90°±10°, it is determined that the wind turbine shaft has an angle misalignment fault.

[0021] When the ratio corresponding to the i-th vibration component is greater than the first threshold and the j-th phase difference is 180°±10°, it is determined that the wind turbine shaft has a parallel misalignment fault.

[0022] Where i belongs to I, I is the total number of vibration components, j belongs to J, J is the total number of phase differences, and a is an integer greater than or equal to 1.

[0023] A second aspect of this application provides a wind turbine shaft fault monitoring system based on pulse amplitude modulation, comprising:

[0024] The acquisition module is used to acquire the pulse amplitude modulation signal of the shaft using a pulse amplitude modulation measurement device installed on the target shaft section of the wind turbine shaft under test. The pulse amplitude modulation signal is generated by the displacement sensor sensing the change in the groove height difference of the grooved tooth disk and the distance change caused by the shaft eccentricity.

[0025] The demodulation module is used to demodulate the amplitude of the pulse amplitude-modulated signal to obtain the eccentric composite vibration component of the rotating shaft;

[0026] The transformation module is used to discretize the eccentric composite vibration components to obtain a discrete time-domain composite vibration component sequence, then perform a Fourier transform on the discrete time-domain composite vibration component sequence to obtain each phase difference, and extract the vibration amplitude and amplitude characteristic parameters of each vibration component at different frequencies.

[0027] The monitoring module is used to monitor the misalignment abnormality of the rotating shaft based on the vibration amplitude, amplitude characteristic parameters and phase difference of each vibration component at different frequencies.

[0028] Preferably, the pulse amplitude modulation measuring device includes: a slotted toothed disc and a displacement sensor.

[0029] Furthermore, the demodulation module is also used for:

[0030] The amplitude envelope of the pulse amplitude-modulated signal is extracted by filtering or envelope detection methods.

[0031] The amplitude envelope is converted into the eccentric vibration component of the rotating shaft based on the sensitivity parameters and bias voltage of the displacement sensor.

[0032] A third aspect of this application provides an electronic device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, it implements the method described in the first aspect embodiment.

[0033] A fourth aspect of this application provides a computer-readable storage medium having a computer program stored thereon that, when executed by a processor, implements the method described in the first aspect.

[0034] The technical solutions provided by the embodiments of this application bring at least the following beneficial effects:

[0035] This application proposes a method and system for monitoring wind turbine shaft faults based on pulse amplitude modulation (PAM). The method includes: acquiring PAM signals of the shaft using a PAM measuring device installed on the target shaft segment of the wind turbine under test; wherein the PAM signals are generated by a displacement sensor sensing changes in the tooth groove height difference of a slotted toothed disk and distance changes caused by shaft eccentricity; demodulating the amplitude of the PAM signals to obtain the eccentric composite vibration components of the shaft; discretizing the eccentric composite vibration components to obtain a discrete-time domain composite vibration component sequence; performing a Fourier transform on the discrete-time domain composite vibration component sequence to obtain phase differences, and extracting the vibration amplitude and amplitude characteristic parameters of each vibration component at different frequencies; and monitoring the misalignment anomaly of the shaft based on the vibration amplitude, amplitude characteristic parameters, and phase differences of each vibration component at different frequencies. The technical solution proposed in this application, by acquiring signals through a PAM measuring device and combining amplitude demodulation and frequency domain analysis, achieves high-precision monitoring and accurate identification of wind turbine shaft misalignment.

[0036] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0037] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0038] Figure 1 This is a flowchart of a wind turbine shaft fault monitoring method based on pulse amplitude modulation according to an embodiment of this application;

[0039] Figure 2 This is a schematic diagram illustrating the principle of shaft eccentricity detection based on an embodiment of this application;

[0040] Figure 3 This is a schematic diagram of the vibration signal generation process of an eccentric shaft according to an embodiment of this application;

[0041] Figure 4 This is a schematic diagram illustrating the correspondence between the time domain and frequency domain of a signal according to an embodiment of this application;

[0042] Figure 5A diagram of an experimental apparatus for measuring pulse amplitude modulation signals according to an embodiment of this application.

[0043] Figure 6 A pulse amplitude modulation signal diagram according to an embodiment of this application.

[0044] Figure 7 This is a structural diagram of a wind turbine shaft fault monitoring system based on pulse amplitude modulation, according to an embodiment of this application. Detailed Implementation

[0045] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0046] This application proposes a method and system for monitoring wind turbine shaft faults based on pulse amplitude modulation (PAM). The method includes: acquiring PAM signals of the shaft using a PAM measuring device installed on the target shaft segment of the wind turbine shaft under test, wherein the PAM signals are generated by a displacement sensor sensing changes in the tooth groove height difference of a slotted toothed disk and distance changes caused by shaft eccentricity; demodulating the amplitude of the PAM signals to obtain the eccentric composite vibration components of the shaft; discretizing the eccentric composite vibration components to obtain a discrete-time domain composite vibration component sequence, then performing a Fourier transform on the discrete-time domain composite vibration component sequence to obtain each phase difference, and extracting the vibration amplitude and amplitude characteristic parameters of each vibration component at different frequencies; and monitoring the misalignment anomaly of the shaft based on the vibration amplitude, amplitude characteristic parameters, and phase differences of each vibration component at different frequencies. The technical solution proposed in this application, by acquiring signals through a PAM measuring device and combining amplitude demodulation and frequency domain analysis, achieves high-precision monitoring and accurate identification of wind turbine shaft misalignment.

[0047] The following description, with reference to the accompanying drawings, illustrates a method and system for monitoring wind turbine shaft faults based on pulse amplitude modulation (PAM).

[0048] Example 1

[0049] Figure 1 This is a flowchart illustrating a wind turbine shaft fault monitoring method based on pulse amplitude modulation, according to an embodiment of this application. Figure 1 As shown, the method includes:

[0050] Step 1: Use a pulse amplitude modulation measurement device installed on the target shaft section of the wind turbine shaft under test to collect the pulse amplitude modulation signal of the shaft. The pulse amplitude modulation signal is generated by the displacement sensor sensing the change in the groove height difference of the grooved tooth disk and the distance change caused by the shaft eccentricity.

[0051] It should be noted that, as Figure 2 The diagram shown illustrates the pulse amplitude modulation principle under shaft misalignment.

[0052] Misalignment caused by bearing assembly errors results in real-time vibration components during operation.

[0053] For a rotating shaft with a smooth surface and in an eccentric state, the displacement sensor senses the displacement change on the shaft surface and outputs a displacement signal with varying amplitude, such as... Figure 1 As shown, during the operation of the shaft, the pulse signal generated by the displacement measuring slotted toothed disc is modulated by the eccentricity, exhibiting a pulse amplitude modulation phenomenon.

[0054] Pulses can be used to determine the phase of a vibration signal, so the phase of the vibration signal can be obtained while demodulating the modulation component of the pulse signal.

[0055] It should be noted that the pulse amplitude modulation measurement device includes: a slotted toothed disc and a displacement sensor.

[0056] It should be noted that, as Figure 3 As shown, by sensing the change in the height difference of the tooth groove through the displacement sensor, the output displacement signal can be approximated as a pulse signal, i.e., a pulse amplitude modulation signal.

[0057] Step 2: Demodulate the amplitude of the pulse amplitude-modulated signal to obtain the eccentric composite vibration component of the rotating shaft;

[0058] In this embodiment of the disclosure, step 2 specifically includes:

[0059] The amplitude envelope of the pulse amplitude-modulated signal is extracted by filtering or envelope detection methods.

[0060] The amplitude envelope is converted into the eccentric vibration component of the rotating shaft based on the sensitivity parameters and bias voltage of the displacement sensor.

[0061] It should be noted that the vibration component, i.e., the eccentric composite vibration component, can be obtained by demodulating the amplitude of the pulse signal, i.e., the pulse amplitude-modulated signal. Furthermore, the vibration response can satisfy the modal superposition condition. The vibration response of the shaft during variable speed operation can be expressed as:

[0062]

[0063] In the formula, B(x,t) represents the vibration response of the shaft during variable speed operation; Nb This indicates the order of the vibration mode; this value is a positive integer greater than 0. B represents the vibration phase; ω(x,t) represents the angular velocity at any position along the length of the shaft; i (ω(x,t)) represents a vibration signal whose amplitude is modulated by the angular velocity ω(x,t);

[0064] The maximum angular frequency shift of the vibration frequency due to frequency conversion modulation is:

[0065]

[0066] In the formula, ω represents the maximum change in angular velocity of the shaft after it is subjected to an external disturbance; c (x,t) represents the working angular velocity of the shaft at any position along its length in a undisturbed state; ω(x,t) represents the total angular velocity of the shaft at any position along its length; [a,b] represents the time range;

[0067] Angular frequency offset is an indicator of the vibration frequency modulation depth. In practical applications, the angular velocity fluctuation caused by speed control deviation is much smaller than the instantaneous angular velocity. Therefore, it can be approximated as a steady rotational speed, and the effect of rotational frequency fluctuation on the frequency modulation of the vibration components can be ignored.

[0068]

[0069] In the formula, The sum of disturbance angular velocities, ω(t) represents the total angular velocity of the shaft, which includes all disturbance components and the working angular velocity.

[0070] Specifically, during the measurement process, the vibration component caused by the eccentricity of the rotating shaft of the displacement sensor changes the distance between the measuring point and the slotted toothed disk. The output pulse signal then exhibits amplitude modulation, and the modulation component is the eccentric vibration component, i.e., the eccentric composite vibration component. The implementation process includes:

[0071] S21, the displacement sensor of the pulse amplitude modulation measuring device senses the change in distance to the encoder disk ("encoder disk" refers to a "slotted toothed disk"), and uses the projection point of the measuring point on the slotted toothed disk as a reference to decompose the vibration at that point into two vibration components: tangential and normal. That is, the component of the vibration signal with the rotational frequency as the fundamental frequency is frequency-modulated at the instantaneous angular frequency. Based on the above analysis, the tangential and normal vibration components are expressed as:

[0072]

[0073] In the formula, θ(x,t) represents the total angle during the rotation of the axis, which is equivalent to integrating over ω(x,t). y (x,t) represents the tangential vibration component, Vz (x,t) represents the normal vibration component, the specific form of which is obtained by actual measurement using a displacement sensor.

[0074] S22, the tangential vibration component of eccentric vibration can be approximately expressed as θ y (x,t), the frequency of the modulation pulse signal, the angular motion of the shaft can be expressed as:

[0075] θ(x,t)=θ c (t)+θ y (x,t) (2-5)

[0076] In the formula, θ y (x,t) represents the tangential component of the eccentric vibration, and the angular vibration is approximately equal to the tangential linear vibration θ. y (x,t)≈V y (x,t), θ c (t) represents the angle θ that the shaft rotates through at the operating speed. y (x,t) represents the vibration caused by eccentricity, and the corresponding tangential angular component.

[0077] S23. The influence of the tangential vibration component on the shaft angular velocity is relatively weak because the linear velocity of the tangential vibration component is much smaller than the linear velocity of the rotational motion, thus having a small impact on the instantaneous angular velocity. In reality, the vibration component modulates the amplitude of the rotational speed pulse. During the calculation of the pulse signal timestamp using the voltage comparison value, the amplitude-modulated component can cause two types of comparisons: leading and lagging. Furthermore, the frequencies of these leading and lagging comparisons are the same as the frequency of the vibration component. This analysis represents the main influencing mechanism in the eccentricity measurement process.

[0078] S24. Under the same amplitude value, the closer the ramp angle of the transition edge of the original pulse signal is to 90°, the better the instantaneity of the high-low switching process of the pulse signal, the smaller the lead or lag comparison in the pulse transition time calculation process, and the smaller the impact on vibration measurement. Conversely, the longer the high-low level transition process takes, the smaller the lead or lag comparison in the pulse timestamp calculation process, and the more significant the vibration.

[0079] S25, the amplitude of the pulse amplitude modulation signal, can be used to obtain the pulse signal output by the slotted toothed disc under vibration. Substituting equation (2-5) into the equation, we get the amplitude-frequency modulation pulse signal, i.e.:

[0080]

[0081] In the formula, P r (t) and P f (t) represent the high and low levels of the pulse signal, respectively, U z(x,t) is the voltage signal output by the displacement sensor for the normal vibration component.

[0082] t n,1 ,t n,2 t represents the time points corresponding to the rising and falling edges of the current pulse period. n,2 ,t n+1,1 This indicates the time points corresponding to the falling edge of the current pulse cycle and the rising edge of the next pulse cycle.

[0083] The relationship between the analog signal output by the displacement sensor and the actual vibration components can be expressed as:

[0084] U z (x,t)=U offset +p z (x,t)s+V(x,t) (2-7)

[0085] In the formula, U offset p is the bias voltage of the sensor. z (x,t) represents the distance between the measuring point and the encoder disk, and s represents the sensitivity of the displacement sensor, in mm / V.

[0086] Step 3: Discretize the eccentric composite vibration components to obtain a discrete-time composite vibration component sequence. Then, perform a Fourier transform on the discrete-time composite vibration component sequence to obtain each phase difference, and extract the vibration amplitude and amplitude characteristic parameters of each vibration component at different frequencies.

[0087] In this embodiment of the disclosure, step 3 specifically includes:

[0088] The frequency domain signal of the eccentric composite vibration component is obtained by performing a Fourier transform on the discrete time domain composite vibration component sequence.

[0089] Based on the frequency domain signal, the vibration amplitude and amplitude characteristic parameters of each vibration component at different frequencies are extracted;

[0090] The Fourier series corresponding to the discrete-time composite vibration component sequence is decomposed using Euler's formula to obtain the coefficients of the Fourier series. The initial phase angle of each vibration component is determined based on the coefficients of the Fourier series, and then the phase difference is determined based on the initial phase angle of each vibration component.

[0091] It should be noted that for a continuous time-domain signal x(t), its discrete form can be written as x(n). The Fourier transform can be expressed as: x(t) replaces the U_z(x,t) signal, because the signal is relatively complex, and using x(t) to replace it makes the subsequent derivation clearer.

[0092]

[0093] In Equation 2-8, X(e jω ) represents the Fourier transform result of the discrete-time domain signal; x(n) represents the discrete-time domain signal; e -jωn It uses Euler's formula to represent Fourier series.

[0094] For signals of finite duration in the time domain, they can be considered as time series truncated by a rectangular window, and equation (2-8) can be rewritten as:

[0095]

[0096] In the formula, n∈[0,N-1], and N is the maximum harmonic order.

[0097] According to Euler's formula, for any real number ω, the following holds:

[0098]

[0099] In Equation 2-11, It uses Euler's formula to represent the nth order Fourier series, a n and b n This represents the coefficients of the Fourier series.

[0100] The phase angle of a signal can be expressed as:

[0101]

[0102] In the formula, This represents the initial phase angle of each component of the signal.

[0103] After obtaining the initial phase angle of each phase using the above method, the phase difference between two phases can be obtained. If the signal is represented as:

[0104]

[0105] In the formula, To measure the initial phase of the signal, x v To obtain the signal, A i ω represents the amplitude components in the measured signal. i The angular velocity components in the measured signal; This represents the phase components of the measured signal; N represents the number of all sinusoidal components in the signal.

[0106] Formula 2-12 uses x v The measured signal is equivalent to the superposition of N sinusoidal signals with different amplitudes, angular velocities, and phases.

[0107] The phase difference between each phase can then be expressed as:

[0108]

[0109] The correspondence between the time domain and frequency domain of a signal is as follows: Figure 4 As shown in the figure. This method extracts the phase using the phase frequency characteristics in the signal frequency domain.

[0110] Step 4: Monitor the misalignment of the rotating shaft based on the vibration amplitude, amplitude characteristic parameters and phase difference of each vibration component at different frequencies.

[0111] In this embodiment of the disclosure, step 4 specifically includes:

[0112] Based on the vibration amplitude of each vibration component at different frequencies, determine the ratio of the vibration amplitude of each vibration component at a+1 times the frequency to the vibration amplitude at a times the frequency.

[0113] When the ratio corresponding to the i-th vibration component is greater than the first threshold and the j-th phase difference is 90°±10°, it is determined that the wind turbine shaft has an angle misalignment fault.

[0114] When the ratio corresponding to the i-th vibration component is greater than the first threshold and the j-th phase difference is 180°±10°, it is determined that the wind turbine shaft has a parallel misalignment fault.

[0115] Where i belongs to I, I is the total number of vibration components, j belongs to J, J is the total number of phase differences, and a is an integer greater than or equal to 1.

[0116] For example, the misalignment experiment of a pulse amplitude modulation signal is performed using the method of this embodiment, as follows:

[0117] Two slotted gear discs are installed on the shaft section at one end of the rotor test bench, such as... Figure 5 As shown, the range is measured using an eddy current sensor and a laser displacement sensor, respectively, and the output pulse amplitude modulation signal is as follows. Figure 6 As shown. Adjust the alignment of this shaft segment to create an eccentric state. Set up two operating conditions: constant speed and variable speed, and collect signals from the two sensors. The amplitude-modulated pulse signal can effectively characterize the information of eccentric vibration and needs to be preserved and demodulated. The demodulated signal is the vibration component caused by eccentricity. Then, by using the jump time point of the rising or falling edge of the pulse signal, the phase of the vibration can be determined. Using this method, slotted gear disks can be deployed on both sides of the shaft segment, and the amplitude-modulated pulse signals output by the displacement sensors on both sides can be collected. Then, the vibration component in the signal can be extracted, and combined with the phase information, the shaft misalignment fault can be identified.

[0118] Table 1. Pulse Amplitude Modulation Measurement Device

[0119]

[0120] A pulse amplitude modulation monitoring device composed of a slotted gear disc and a displacement sensor was used. The parameters of the sensor and measuring equipment are shown in Table 1. Pulse amplitude modulation signals were collected for both constant and variable speed operation. During the constant speed operation phase of the shaft, the vibration caused by the shaft's eccentricity was obtained through the envelope, and the phase information of the vibration signal could be obtained from the timestamp of the pulse signal. The frequency of the speed regulation pulse signal was also modulated by the rotational frequency, and the measured signal conformed to the theoretical derivation. Experiments proved that the proposed pulse amplitude modulation can achieve the detection of shaft eccentricity.

[0121] In summary, the wind turbine shaft fault monitoring method proposed in this embodiment acquires signals through a pulse amplitude modulation measurement device and combines amplitude demodulation and frequency domain analysis to achieve high-precision monitoring of wind turbine shaft misalignment and accurate identification of fault types.

[0122] Example 2

[0123] Figure 7 This is a structural diagram of a wind turbine shaft fault monitoring system based on pulse amplitude modulation according to an embodiment of this application, as shown below. Figure 7 As shown, the system includes:

[0124] The acquisition module 100 is used to acquire the pulse amplitude modulation signal of the shaft using a pulse amplitude modulation measurement device installed on the target shaft section of the wind turbine shaft under test. The pulse amplitude modulation signal is generated by the displacement sensor sensing the change in the groove height difference of the grooved tooth disk and the distance change caused by the shaft eccentricity.

[0125] The pulse amplitude modulation measurement device includes a slotted toothed disc and a displacement sensor.

[0126] The demodulation module 200 is used to perform amplitude demodulation on the pulse amplitude modulation signal to obtain the eccentric composite vibration component of the rotating shaft;

[0127] The transformation module 300 is used to discretize the eccentric composite vibration components to obtain a discrete time-domain composite vibration component sequence, then perform a Fourier transform on the discrete time-domain composite vibration component sequence to obtain each phase difference, and extract the vibration amplitude and amplitude characteristic parameters of each vibration component at different frequencies.

[0128] The monitoring module 400 is used to monitor the misalignment abnormality of the rotating shaft based on the vibration amplitude, amplitude characteristic parameters and phase difference of each vibration component at different frequencies.

[0129] In this embodiment of the disclosure, the demodulation module 200 is further configured to:

[0130] The amplitude envelope of the pulse amplitude-modulated signal is extracted by filtering or envelope detection methods.

[0131] The amplitude envelope is converted into the eccentric vibration component of the rotating shaft based on the sensitivity parameters and bias voltage of the displacement sensor.

[0132] In this embodiment of the disclosure, the transformation module 300 is further configured to:

[0133] The frequency domain signal of the eccentric composite vibration component is obtained by performing a Fourier transform on the discrete time domain composite vibration component sequence.

[0134] Based on the frequency domain signal, the vibration amplitude and amplitude characteristic parameters of each vibration component at different frequencies are extracted;

[0135] The Fourier series corresponding to the discrete-time composite vibration component sequence is decomposed using Euler's formula to obtain the coefficients of the Fourier series. The initial phase angle of each vibration component is determined based on the coefficients of the Fourier series, and then the phase difference is determined based on the initial phase angle of each vibration component.

[0136] In this embodiment of the disclosure, the monitoring module 400 is further configured to:

[0137] Based on the vibration amplitude of each vibration component at different frequencies, determine the ratio of the vibration amplitude of each vibration component at a+1 times the frequency to the vibration amplitude at a times the frequency.

[0138] When the ratio corresponding to the i-th vibration component is greater than the first threshold and the j-th phase difference is 90°±10°, it is determined that the wind turbine shaft has an angle misalignment fault.

[0139] When the ratio corresponding to the i-th vibration component is greater than the first threshold and the j-th phase difference is 180°±10°, it is determined that the wind turbine shaft has a parallel misalignment fault.

[0140] Where i belongs to I, I is the total number of vibration components, j belongs to J, J is the total number of phase differences, and a is an integer greater than or equal to 1.

[0141] In summary, the wind turbine shaft fault monitoring system proposed in this embodiment acquires signals through a pulse amplitude modulation measurement device and combines amplitude demodulation and frequency domain analysis to achieve high-precision monitoring of wind turbine shaft misalignment and accurate identification of fault types.

[0142] Example 3

[0143] To implement the above embodiments, this disclosure also proposes an electronic device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, it implements the method described in Embodiment 1.

[0144] Example 4

[0145] To implement the above embodiments, this disclosure also proposes a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method described in Embodiment 1.

[0146] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0147] Any process or method description in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing custom logic functions or processes, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as should be understood by those skilled in the art to which embodiments of this application pertain.

[0148] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A method for monitoring wind turbine shaft faults based on pulse amplitude modulation, characterized in that, The method includes: The pulse amplitude modulation signal of the wind turbine shaft is acquired by a pulse amplitude modulation measurement device installed on the target shaft section of the wind turbine shaft under test. The pulse amplitude modulation signal is generated by the displacement sensor sensing the change in the groove height difference of the grooved tooth disk and the distance change caused by the shaft eccentricity. The amplitude of the pulse amplitude-modulated signal is demodulated to obtain the eccentric composite vibration component of the rotating shaft; The eccentric composite vibration components are discretized to obtain a discrete-time composite vibration component sequence. Then, the discrete-time composite vibration component sequence is subjected to Fourier transform to obtain each phase difference, and the vibration amplitude and amplitude characteristic parameters of each vibration component at different frequencies are extracted. The misalignment anomaly of the rotating shaft is monitored based on the vibration amplitude, amplitude characteristic parameters, and phase difference of each vibration component at different frequencies.

2. The method as described in claim 1, characterized in that, The pulse amplitude modulation measurement device includes: a slotted toothed disc and a displacement sensor.

3. The method as described in claim 2, characterized in that, The step of demodulating the amplitude of the pulse amplitude-modulated signal to obtain the eccentric vibration component of the rotating shaft includes: The amplitude envelope of the pulse amplitude-modulated signal is extracted by filtering or envelope detection methods. The amplitude envelope is converted into the eccentric vibration component of the rotating shaft based on the sensitivity parameters and bias voltage of the displacement sensor.

4. The method as described in claim 3, characterized in that, The process of performing a Fourier transform on the discrete-time composite vibration component sequence to obtain each phase difference, and extracting the vibration amplitude and amplitude characteristic parameters of each vibration component at different frequencies, includes: The frequency domain signal of the eccentric composite vibration component is obtained by performing a Fourier transform on the discrete time domain composite vibration component sequence. Based on the frequency domain signal, the vibration amplitude and amplitude characteristic parameters of each vibration component at different frequencies are extracted; The Fourier series corresponding to the discrete-time composite vibration component sequence is decomposed using Euler's formula to obtain the coefficients of the Fourier series. The initial phase angle of each vibration component is determined based on the coefficients of the Fourier series, and then the phase difference is determined based on the initial phase angle of each vibration component.

5. The method as described in claim 4, characterized in that, The monitoring of the misalignment anomaly of the rotating shaft based on the vibration amplitude, amplitude characteristic parameters, and phase difference of each vibration component at different frequencies includes: Based on the vibration amplitude of each vibration component at different frequencies, determine the ratio of the vibration amplitude of each vibration component at a+1 times the frequency to the vibration amplitude at a times the frequency. When the ratio corresponding to the i-th vibration component is greater than the first threshold and the j-th phase difference is 90°±10°, it is determined that the wind turbine shaft has an angle misalignment fault. When the ratio corresponding to the i-th vibration component is greater than the first threshold and the j-th phase difference is 180°±10°, it is determined that the wind turbine shaft has a parallel misalignment fault. Where i belongs to I, I is the total number of vibration components, j belongs to J, J is the total number of phase differences, and a is an integer greater than or equal to 1.

6. A wind turbine shaft fault monitoring system based on pulse amplitude modulation, characterized in that, The system includes: The acquisition module is used to acquire the pulse amplitude modulation signal of the shaft using a pulse amplitude modulation measurement device installed on the target shaft section of the wind turbine shaft under test. The pulse amplitude modulation signal is generated by the displacement sensor sensing the change in the groove height difference of the grooved tooth disk and the distance change caused by the shaft eccentricity. The demodulation module is used to demodulate the amplitude of the pulse amplitude-modulated signal to obtain the eccentric composite vibration component of the rotating shaft; The transformation module is used to discretize the eccentric composite vibration components to obtain a discrete time-domain composite vibration component sequence, then perform a Fourier transform on the discrete time-domain composite vibration component sequence to obtain each phase difference, and extract the vibration amplitude and amplitude characteristic parameters of each vibration component at different frequencies. The monitoring module is used to monitor the misalignment abnormality of the rotating shaft based on the vibration amplitude, amplitude characteristic parameters and phase difference of each vibration component at different frequencies.

7. The system as described in claim 6, characterized in that, The pulse amplitude modulation measurement device includes: a slotted toothed disc and a displacement sensor.

8. The system as described in claim 7, characterized in that, The demodulation module is also used for: The amplitude envelope of the pulse amplitude-modulated signal is extracted by filtering or envelope detection methods. The amplitude envelope is converted into the eccentric vibration component of the rotating shaft based on the sensitivity parameters and bias voltage of the displacement sensor.

9. An electronic device, characterized in that, include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the program, implements the method as described in any one of claims 1-5.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the method as described in any one of claims 1-5.

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