An online diagnosis method, system and device for wind wheel unbalance state

Abstract

The application discloses an online diagnosis method, system and device for a wind wheel unbalance state, relates to the field of fault monitoring, and comprises determining a blade vibration frequency and an axial rotation frequency in an axial vibration spectrum of a wind wheel output shaft; when a problem occurs in a certain blade, the wind wheel is unbalanced, the rotation center of the wind wheel is offset, and the axial vibration spectrum of the wind wheel output shaft is characterized in that, in addition to the blade vibration frequency, the axial rotation frequency also exists, and is positively correlated with the unbalance degree of the blade, so that the ratio of the axial rotation frequency to the blade vibration frequency is used to measure the unbalance degree, and greater than a first threshold value may cause a fault. In the process of wind wheel operation, direct detection is carried out, fault detection is more timely, and safety problems caused by fault discovery delay are avoided. In addition, the ratio of the axial rotation frequency to the blade vibration frequency is used to measure the unbalance degree to determine the wind wheel unbalance fault, and the fault can be more accurately determined.

Description

Technical Field

[0001] This invention relates to the field of fault monitoring, and in particular to an online diagnostic method, system, and device for wind turbine imbalance. Background Technology

[0002] A wind turbine consists of a rotor, nacelle, and tower. The blades in the rotor rotate around the main shaft inside the nacelle under the influence of wind force, and the tower supports the nacelle. The rotor is the key component of the wind turbine that converts wind energy into kinetic energy. Due to the influence of the production, installation, and operating environment, rotor imbalance faults are prone to occur, which can lead to fatigue damage to the transmission or connection components of the wind turbine, reduce power generation efficiency, and in severe cases, may even cause catastrophic accidents such as blade breakage and turbine collapse.

[0003] Therefore, detecting whether the wind turbine rotor is unbalanced is very important for the operation of the wind turbine. Summary of the Invention

[0004] The purpose of this invention is to provide an online diagnostic method, system, and device for wind turbine imbalance. The degree of imbalance is measured by the ratio of axial rotational frequency to blade vibration frequency; if the ratio exceeds a first threshold, a fault may occur. If the trajectory of the shaft center deviates and meets the fault threshold rule, it indicates a possible imbalance. If both conditions are met simultaneously, an imbalance fault is confirmed in the wind turbine, leading to a more accurate fault diagnosis.

[0005] To address the aforementioned technical problems, this invention provides an online diagnostic method for wind turbine imbalance, comprising:

[0006] The blade vibration frequency and axial rotation frequency in the axial vibration spectrum of the wind turbine output shaft are determined. The axial rotation frequency is positively correlated with the degree of imbalance of the wind turbine blades, and the blade vibration frequency is positively correlated with the number of blades.

[0007] When the ratio of the axial rotational frequency to the blade vibration frequency exceeds a first threshold, it is determined that the wind turbine has an imbalance fault.

[0008] On the other hand, determining the blade vibration frequency and axial rotation frequency in the axial vibration spectrum of the wind turbine output shaft includes:

[0009] The acceleration a of the axial displacement of the wind turbine output shaft within a preset time t is obtained. x (t);

[0010] Based on the acceleration ax(t) of the axial displacement and the relationship between the axial displacement and s x (t)=∫∫a x (t) Determine the axial displacement s of the wind turbine output shaft. x (t);

[0011] The blade vibration frequency and the axial rotation frequency are determined based on the axial vibration displacement spectrum formed by the axial displacement.

[0012] On the other hand, determining the blade vibration frequency and the axial rotation frequency based on the spectrum formed by the axial displacement includes:

[0013] The frequency corresponding to the maximum value of the axial displacement determined within the first preset frequency range of the axial vibration displacement spectrum is taken as the axial rotation frequency.

[0014] The frequency corresponding to the maximum value of the axial displacement determined within the second preset frequency range of the axial vibration displacement spectrum is taken as the blade vibration frequency.

[0015] Wherein, the first preset frequency range is the average rotational frequency f of the wind turbine within the preset time period. n0 Centered on the average rotor speed f within the preset time period, the second preset frequency range is defined as follows: n0 Centered on k times the value of the blades, where k is the number of blades.

[0016] On the other hand, the process of determining the average rotational frequency of the wind turbine within the preset time period includes:

[0017] Determine the rotational speed v(t) of the wind turbine within a preset time t;

[0018] The average rotational speed within the preset time t is determined based on the rotational speed within the preset time t.

[0019] Based on the relationship between the average rotational speed and rotational frequency Determine the average rotation frequency within the preset time t.

[0020] On the other hand, before using the frequency corresponding to the maximum value of the axial displacement determined within the first preset frequency range of the axial vibration displacement spectrum as the axial rotation frequency, the method further includes:

[0021] Set the search range △f;

[0022] The frequency corresponding to the maximum value of the axial displacement determined within a first preset frequency range of the axial vibration displacement spectrum is taken as the axial rotation frequency, including:

[0023] In the first preset frequency range f of the axial vibration displacement spectrum a =[f n0 -△f,f n0 The frequency corresponding to the maximum value of the axial displacement within the range of +△f] is taken as the axial rotation frequency s. Zx (f nx );

[0024] The frequency corresponding to the maximum value of the axial displacement determined within the second preset frequency range of the axial vibration displacement spectrum is taken as the blade vibration frequency, including:

[0025] In the second preset frequency range f of the axial vibration displacement spectrum b =[kf n0 -△f,kf n0 The frequency corresponding to the maximum value of the axial displacement determined within +△f] is taken as the blade vibration frequency s. Zx (f knx ).

[0026] On the other hand, it also includes:

[0027] Determine the motion trajectory of the shaft center of the wind turbine output shaft;

[0028] When the ratio of the axial rotational frequency to the blade vibration frequency exceeds a first threshold, an imbalance fault is determined in the wind turbine, including:

[0029] If the ratio of the axial rotational frequency to the blade vibration frequency exceeds a first threshold and the motion trajectory of the shaft center satisfies the fault threshold rule, it is determined that the wind turbine has an imbalance fault.

[0030] On the other hand, determining the motion trajectory of the shaft center of the wind turbine output shaft includes:

[0031] Obtain the acceleration a of the radial horizontal displacement within a preset time t. y (t) and the acceleration a of the radial vertical displacement within the preset time t. z (t);

[0032] According to the acceleration a of the radial horizontal displacement y (t), the acceleration a of the radial vertical displacement z (t), radial horizontal displacement relationship s y (t)=∫∫a y (t) and the relationship between radial and vertical displacement s z (t)=∫∫a z (t) Determine the radial horizontal displacement s y (t) and the radial vertical displacement s z (t);

[0033] According to the radial horizontal displacement s y (t) and the radial vertical displacement s z (t) determines the motion trajectory r(t) of the axis.

[0034] On the other hand, the process of determining whether the motion trajectory satisfies the fault threshold rule includes:

[0035] The amplitude ratio s of the major axis to the minor axis of the figure formed by the motion trajectory is determined based on the motion trajectory of the axis. max ;

[0036] In the amplitude ratio s max Not less than the preset value s k If so, the motion trajectory is determined to satisfy the fault threshold rule.

[0037] On the other hand, determining that the wind turbine has an imbalance fault when the ratio of the axial rotational frequency to the blade vibration frequency exceeds a first threshold and the motion trajectory of the shaft center satisfies the fault threshold rule includes:

[0038] When the ratio of the axial rotation frequency to the blade vibration frequency exceeds a second threshold, it is determined that the first fault warning condition is met; when the ratio of the axial rotation frequency to the blade vibration frequency exceeds the first threshold, it is determined that the first fault alarm condition is met, wherein the first threshold is greater than the second threshold.

[0039] In the amplitude ratio s max When the value is 1, the second fault warning condition is determined to be met, and the amplitude ratio s max The value is not less than the preset value s k When the second fault alarm condition is met, the preset value s is determined to be satisfied. k Greater than 1;

[0040] The ratio of the axial rotational frequency to the blade vibration frequency meets the first fault warning condition or the first fault alarm condition; and the amplitude ratio s max If the second fault warning condition or the second fault alarm condition is met, it is determined that the wind turbine has an imbalance fault.

[0041] On the other hand, the ratio of the axial rotational frequency to the blade vibration frequency meets the first fault warning condition or the first fault alarm condition; and the amplitude ratio s max When the second fault warning condition or the second fault alarm condition is met, it is determined that the wind turbine has an imbalance fault, which also includes:

[0042] If an imbalance fault is determined in the wind turbine, a pre-alarm level is established based on the ratio of the axial rotation frequency to the blade vibration frequency, and the amplitude ratio s is used. max The lower of the eligible pre-alarm levels determines the level of the wind turbine imbalance fault.

[0043] To address the aforementioned technical problems, the present invention also provides an online diagnostic system for wind turbine imbalance, comprising:

[0044] The frequency determination unit is used to determine the blade vibration frequency and axial rotation frequency in the axial vibration spectrum of the wind turbine output shaft. The axial rotation frequency is positively correlated with the degree of imbalance of the wind turbine blades, and the blade vibration frequency is positively correlated with the number of blades.

[0045] The fault determination unit is used to determine that the wind turbine has an imbalance fault when the ratio of the axial rotation frequency to the blade vibration frequency exceeds a first threshold value.

[0046] To address the aforementioned technical problems, the present invention also provides an online diagnostic device for wind turbine imbalance, comprising:

[0047] Memory, used to store computer programs;

[0048] A processor is used to implement the steps of the online diagnostic method for wind turbine imbalance described above when executing the computer program.

[0049] This invention discloses an online diagnostic method, system, and device for wind turbine imbalance. When a blade malfunctions, causing wind turbine imbalance and a shift in the turbine's rotation center, the axial vibration spectrum of the turbine's output shaft will exhibit an axial rotational frequency in addition to the blade vibration frequency. This axial rotational frequency is positively correlated with the degree of blade imbalance. Therefore, the ratio of the axial rotational frequency to the blade vibration frequency is used to measure the degree of imbalance. If the ratio exceeds a preset threshold, the wind turbine is considered to be in an imbalance fault. This invention proposes using the ratio of the axial rotational frequency to the blade vibration frequency to measure the degree of imbalance and determine if a wind turbine is in an imbalance fault, which can more accurately identify the fault. Furthermore, this method can perform real-time data acquisition and monitoring during wind turbine operation, enabling real-time monitoring of the wind turbine's operating status and avoiding safety issues caused by delayed fault detection. Further, it is determined that the axial trajectory of the wind turbine's output shaft in a normal state should be a stable ellipse with minimal difference between its major and minor axes. In an imbalanced state, the trajectory will deviate. If the trajectory deviates and meets the fault threshold law, the wind turbine can also be considered to be in an imbalanced state. Therefore, this method also combines the ratio of the major and minor axis amplitudes of the motion trajectory of the wind turbine output shaft center to determine whether the wind turbine is in an unbalanced motion state; and provides a fusion diagnostic method that uses the ratio of the axial rotation frequency to the blade vibration frequency and the motion trajectory of the shaft center to simultaneously determine the wind turbine unbalanced state, further improving the accuracy of monitoring. Attached Figure Description

[0050] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the prior art and embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0051] Figure 1 A flowchart of an online diagnostic method for wind turbine imbalance provided by the present invention;

[0052] Figure 2 A schematic diagram of the structure of a wind turbine generator provided by the present invention;

[0053] Figure 3 A schematic diagram of the motion trajectory for constructing an axis provided by the present invention;

[0054] Figure 4 A schematic diagram of the structure of an online diagnostic system for wind turbine imbalance provided by the present invention;

[0055] Figure 5 This is a schematic diagram of the structure of an online diagnostic device for wind turbine imbalance provided by the present invention. Detailed Implementation

[0056] The core of this invention is to provide an online diagnostic method, system, and device for wind turbine imbalance. The degree of imbalance is measured by the ratio of axial rotational frequency to blade vibration frequency; if the ratio exceeds a first threshold, a fault may occur. If the trajectory of the shaft center deviates and meets the fault threshold rule, it indicates a possible imbalance. If both conditions are met simultaneously, an imbalance fault in the wind turbine is confirmed.

[0057] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0058] Figure 1 The flowchart illustrates an online diagnostic method for wind turbine imbalance provided by this invention. Figure 2 A schematic diagram of the structure of a wind turbine generator provided by the present invention;

[0059] The online diagnostic methods for wind turbine imbalance include:

[0060] S11: Determine the blade vibration frequency and axial rotation frequency in the axial vibration spectrum of the wind turbine output shaft. The axial rotation frequency is positively correlated with the degree of imbalance of the wind turbine blades, and the blade vibration frequency is positively correlated with the number of blades.

[0061] When a wind turbine is in normal equilibrium, its blades rotate around the output shaft. As the blades pass through the tower, they experience a reaction force from the tower. Therefore, for each rotation, the turbine experiences several forces of equal amplitude from the blades, which manifests as a distinct blade-passing vibration frequency in the axial vibration spectrum of the output shaft. When a blade malfunctions, causing turbine imbalance, the turbine's rotation center shifts, and the forces acting on the blades before passing through the tower become inconsistent. Consequently, for each rotation, the turbine experiences at least one force of varying amplitude, resulting in an axial rotation frequency in the output shaft's axial vibration spectrum, in addition to the blade vibration frequency. Therefore, the characteristics of wind turbine imbalance are: the axial vibration spectrum exhibits a distinct axial rotation frequency in addition to the blade vibration frequency; the more severe the imbalance, the more pronounced the axial rotation frequency. The degree of imbalance can be measured by the amplitude ratio of the axial rotation frequency to the blade vibration frequency.

[0062] S12: When the ratio of axial rotation frequency to blade vibration frequency exceeds the first threshold, it is determined that the wind turbine has an imbalance fault.

[0063] The fact that the amplitude ratio of axial rotation frequency to blade vibration frequency exceeds the first threshold indicates that the current axial rotation frequency is too high and that there is a significant imbalance in the frequency domain.

[0064] This invention discloses an online diagnostic method for wind turbine imbalance. When a blade malfunctions, causing wind turbine imbalance and a shift in the turbine's rotation center, the axial vibration spectrum of the turbine's output shaft will exhibit an axial rotational frequency in addition to the blade vibration frequency. This axial rotational frequency is positively correlated with the degree of blade imbalance. Therefore, the ratio of the axial rotational frequency to the blade vibration frequency is used to measure the degree of imbalance. If the ratio exceeds a preset threshold, the wind turbine is considered to have an imbalance fault. This invention proposes using the ratio of the axial rotational frequency to the blade vibration frequency to measure the degree of imbalance and determine the presence of an imbalance fault in the wind turbine, which allows for more accurate fault identification. Furthermore, this method enables real-time data acquisition and monitoring during wind turbine operation, achieving real-time monitoring of the wind turbine's operating status and avoiding safety issues caused by delayed fault detection.

[0065] Based on the above embodiments:

[0066] In some embodiments, determining the blade vibration frequency and axial rotational frequency in the axial vibration spectrum of the wind turbine output shaft includes:

[0067] The axial displacement acceleration 'a' is acquired by an axial sensor located below the wind turbine output shaft within a preset time t. x (t);

[0068] Based on the acceleration ax(t) of the axial displacement and the relationship between the axial displacement and s x (t)=∫∫a x(t) Determine the axial displacement s of the wind turbine output shaft x (t);

[0069] The blade vibration frequency and axial rotation frequency are determined based on the axial vibration displacement spectrum formed by the axial displacement.

[0070] A vibration coordinate accelerometer is installed below the wind turbine output shaft, with sensors for axial, radial horizontal, and radial vertical directions. Since the axial sensor collects axial acceleration, it needs to be integrated and converted into axial displacement.

[0071] Because the wind turbine rotates at a low speed, the spectral resolution df needs to reach a certain accuracy in order to facilitate spectral analysis. At this time, the corresponding single sample sampling time T = 1 / df, that is, when df = 0.1Hz, T = 10s, and the axial sensor sampling time t > 10s.

[0072] In some embodiments, determining the blade vibration frequency and axial rotation frequency based on the spectrum formed by the axial displacement includes:

[0073] The frequency corresponding to the maximum value of the axial displacement determined within the first preset frequency range of the axial vibration displacement spectrum is taken as the axial rotation frequency.

[0074] The frequency corresponding to the maximum value of the axial displacement determined within the second preset frequency range of the axial vibration displacement spectrum is taken as the blade vibration frequency.

[0075] The first preset frequency range is defined as the average rotational frequency f of the wind turbine within a preset time period. n0 Centered on the average rotor speed f within a preset time period, the second preset frequency range is defined as follows: n0 Centered on k times the value of the blade, where k is the number of blades.

[0076] To avoid errors in frequency search due to sampling accuracy, we consider searching for the maximum value within a certain range around the theoretical frequency. This value is the actual axial frequency: (f...) n0 Centered on the first preset frequency range, the actual frequency search band is determined, and the maximum value in the spectrum of the axial vibration displacement of the main shaft is searched.

[0077] To avoid errors in blade frequency search due to sampling accuracy, the maximum value is searched within a certain range around the theoretical blade vibration frequency. This value is the actual blade vibration frequency. Taking k times the first order of the actual axial vibration as the center, i.e., k times the actual blade vibration frequency, the second preset frequency range is determined as the actual rotation frequency search band, and the maximum value of the main shaft axial vibration displacement spectrum is searched.

[0078] In some embodiments, the process of determining the average rotational frequency of the wind turbine within a preset time period includes:

[0079] Determine the rotational speed v(t) of the wind turbine within a preset time t;

[0080] The average rotational speed within the preset time t is determined based on the rotational speed within the preset time t.

[0081] Based on the relationship between average rotational speed and rotational frequency Determine the average rotation frequency within a preset time t.

[0082] SCADA (Supervisory Control and Data Acquisition) system: This system acquires and monitors data to control the turbine. It uses sensors installed at key locations within the turbine to collect operating parameters such as vibration, temperature, and operating time, identifies any exceeding limits, and controls the turbine based on these parameters. This application can determine the average rotational speed over a preset time t based on the rotor speed data collected by the SCADA system, and then determine the average rotational frequency based on the correlation between speed and frequency.

[0083] Furthermore, since the wind turbine rotates at a low speed, speed fluctuations have a significant impact on the rotational frequency and the passing frequency of the blades. Obtaining the real-time rotational speed signal of the wind turbine allows for the calculation of a more accurate rotational frequency value during the monitoring period.

[0084] In some embodiments, before using the frequency corresponding to the maximum value of the axial displacement determined within a first preset frequency range of the axial vibration displacement spectrum as the axial rotation frequency, the method further includes:

[0085] Set the search range △f;

[0086] The frequency corresponding to the maximum value of the axial displacement determined within a first preset frequency range of the axial vibration displacement spectrum is taken as the axial rotation frequency, including:

[0087] Within the first preset frequency range f of the axial vibration displacement spectrum a =[f n0 -△f,f n0 The frequency corresponding to the maximum value of the axial displacement within the range of +△f] is taken as the axial rotation frequency s. Zx (f nx );

[0088] The frequency corresponding to the maximum value of the axial displacement determined within the second preset frequency range of the axial vibration displacement spectrum is taken as the blade vibration frequency, including:

[0089] In the second preset frequency range f of the axial vibration displacement spectrum b =[kf n0 -△f,kf n0 The frequency corresponding to the maximum value of the axial displacement determined within +△f] is taken as the blade vibration frequency s.Zx (f knx ).

[0090] The search range Δf is set by the actual sampling frequency and the actual sampling time. Since the first preset frequency range is based on f... n0 Centered on f, the first preset frequency range is f when the search range is Δf. a =[f n0 -△f,f n0 +△f]. Since the second search range is k times f. n0 Therefore, when the search range is Δf, the second preset frequency range is f. b =[kf n0 -△f,kf n0 +△f).

[0091] The frequency corresponding to the maximum value of the axial displacement obtained by searching within the first preset frequency range and the second preset frequency range is taken as the actual axial rotation frequency and blade vibration frequency within that time period.

[0092] In some embodiments, it also includes:

[0093] Determine the motion trajectory of the wind turbine output shaft centerline;

[0094] When the ratio of axial rotational frequency to blade vibration frequency exceeds a first threshold, an imbalance fault in the wind turbine is determined, including:

[0095] If the ratio of axial rotation frequency to blade vibration frequency exceeds the first threshold and the trajectory of the shaft center meets the fault threshold rule, it is determined that the wind turbine has an imbalance fault.

[0096] The trajectory of the center point of the rotor shaft is the shaft center trajectory. Under normal conditions, the rotor shaft center trajectory should be a relatively stable ellipse with a small difference between its major and minor axes. In reality, due to imbalance, misalignment, or other issues, the rotor shaft center changes. In an unbalanced state, the rotor's rotation center trajectory will shift, and its shaft center trajectory will appear as a circle or an ellipse with a large difference between its major and minor axes. Therefore, by detecting the trajectory of the shaft center, the unbalanced state of the rotor can be determined.

[0097] If the trajectory of the axis of motion satisfies the fault threshold rule, it proves that the imbalance in the time domain is relatively large.

[0098] Specifically, the fault threshold rule can be that the shape of the motion trajectory approaches a preset shape.

[0099] In some embodiments, determining the motion trajectory of the wind turbine output shaft centerline includes:

[0100] The radial horizontal displacement acceleration 'a' is acquired by a radial horizontal sensor located below the wind turbine output shaft within a preset time t. y (t) and the acceleration a of the radial vertical displacement collected by the radial vertical sensor located below the wind turbine output shaft within a preset time t. z (t);

[0101] Based on the acceleration a of the radial horizontal displacement y (t) The acceleration a of the radial vertical displacement z (t), radial horizontal displacement relationship s y (t)=∫∫a y (t) and the relationship between radial and vertical displacement s z (t)=∫∫a z (t) Determine the radial horizontal displacement s y (t) and radial vertical displacement s z (t);

[0102] Based on radial horizontal displacement s y (t) and radial vertical displacement s z (t) determines the trajectory r(t) of the axis of motion.

[0103] Figure 3 A schematic diagram of the motion trajectory for constructing an axis provided by the present invention;

[0104] Typically, two mutually perpendicular sensors—a radial horizontal sensor and a radial vertical sensor—are mounted on a plane perpendicular to the axis, and their time-domain waveform data are combined to create a display of the axis trajectory. Figure 2 3D dynamic single graph, such as Figure 3 As shown.

[0105] A vibration three-coordinate accelerometer is installed below the wind turbine output shaft, with axial, radial horizontal, and radial vertical sensors in three directions. Since the radial horizontal and radial vertical sensors collect radial horizontal and radial vertical accelerations, they need to be integrated and converted into radial horizontal and radial vertical displacements.

[0106] In some embodiments, the process of determining whether a motion trajectory satisfies a fault threshold rule includes:

[0107] Determine the amplitude ratio s of the major axis to the minor axis of the figure formed by the motion trajectory based on the trajectory of the axis. max ;

[0108] In amplitude ratio s max Not less than the preset value s k If so, the motion trajectory is determined to satisfy the fault threshold rule.

[0109] Because the vibration signal of a wind turbine rotor contains not only useful axial rotational frequency, blade vibration frequency and their higher harmonics, but also noise, electromagnetic signals and other interference components, the original shaft center trajectory is quite complex. Therefore, the displacement signal can be pre-processed to remove noise and purify it, highlighting key factors such as rotational frequency. Furthermore, a first-harmonic shaft center trajectory can be plotted to extract the true trajectory of the imbalance.

[0110] The shape formed by the axes can be either circular or elliptical. Therefore, the specific shape (circular or elliptical) can be determined based on the amplitude ratio between the major and minor axes, thus determining the degree of imbalance. The degree of imbalance is related to s. max They are positively correlated.

[0111] In some embodiments, determining that the wind turbine has an imbalance fault when the ratio of the axial rotational frequency to the blade vibration frequency exceeds a first threshold and the trajectory of the shaft center meets the fault threshold rule includes:

[0112] When the ratio of axial rotation frequency to blade vibration frequency exceeds the second threshold, the first fault warning condition is determined to be met; when the ratio of axial rotation frequency to blade vibration frequency exceeds the first threshold, the first fault alarm condition is determined to be met. The first threshold is greater than the second threshold.

[0113] In amplitude ratio s max When the value is 1, the second fault warning condition is met, and the amplitude ratio s max The value is not less than the preset value s k When the second fault alarm condition is met, the preset value s is set. k Greater than 1;

[0114] The ratio of axial rotational frequency to blade vibration frequency meets the first fault warning condition or the first fault alarm condition; and the amplitude ratio s max If the conditions for the second fault warning or the second fault alarm are met, it is determined that the wind turbine has an imbalance fault.

[0115] In some embodiments, the ratio of axial rotational frequency to blade vibration frequency meets the first fault warning condition or the first fault alarm condition; and the amplitude ratio s max If the second fault warning condition or the second fault alarm condition is met, it is determined that the wind turbine has an imbalance fault, which also includes:

[0116] If an imbalance fault is determined in the wind turbine, the pre-alarm level and amplitude ratio s should be determined according to the ratio of axial rotation frequency to blade vibration frequency. max The lower of the eligible early warning levels determines the level of wind turbine imbalance fault.

[0117] Therefore, the determination of wind turbine imbalance faults is transformed into determining the axial rotational frequency (S). Zx (fnx ) and blade vibration frequency s Zx (f knx The ratio w exceeds the first threshold value w k And the amplitude ratio s max Not less than the preset value s k .

[0118] Different threshold values ​​can be set according to the degree of wind turbine imbalance. Typically, two thresholds are set: a warning threshold and an alarm threshold. When the second threshold is reached, a fault warning is issued; when the first threshold is reached, a fault alarm is issued. The first threshold value must be greater than the second threshold value.

[0119] If the trajectory of the axis is a circle or an ellipse with a large difference between its major and minor axes, then s max =1 or s max Greater than s k When the wind turbine is unbalanced, the condition is met, where s k This is a limit value for the amplitude ratio of the major axis to the minor axis of the motion trajectory. In practice, it can be adjusted according to the needs of on-site maintenance. max Greater than s k This indicates that the trajectory of the axis is an ellipse with significant differences between its major and minor axes, s max =1 indicates that the axis trajectory is circular. Similarly, warning and alarm thresholds can be set for the axis trajectory. For example, a warning is output if the circular rule is met, and an alarm is output if the elliptical rule is met.

[0120] In actual alarm process, if the ratio of axial rotation frequency to blade vibration frequency meets the warning requirement and the amplitude ratio meets the alarm requirement, then the level of wind turbine imbalance fault is determined according to the lower level, i.e., the warning level.

[0121] To further achieve accurate diagnosis and maintenance guidance, a comprehensive decision can be output based on the consistency of diagnostic conclusions from multiple consecutive single samples. For example, if there are 6 consecutive alarm levels of alarm or higher among 10 consecutive single samples, an alarm is output; if there are 6 consecutive alarm levels of warning or higher, a warning is output; if neither of the above conditions is met, normal is output.

[0122] Figure 4 This is a schematic diagram of an online diagnostic system for wind turbine imbalance provided by the present invention. The online diagnostic system for wind turbine imbalance includes:

[0123] The frequency determination unit 41 is used to determine the blade vibration frequency and axial rotation frequency in the axial vibration spectrum of the wind turbine output shaft. The axial rotation frequency is positively correlated with the degree of imbalance of the wind turbine blades, and the blade vibration frequency is positively correlated with the number of blades.

[0124] The fault determination unit 42 is used to determine that the wind turbine has an imbalance fault when the ratio of the axial rotation frequency to the blade vibration frequency exceeds the first threshold value and the motion trajectory meets the fault threshold rule.

[0125] Based on the above embodiments:

[0126] The axial displacement acceleration acquisition unit is used to acquire the acceleration a of the axial displacement set on the wind turbine output shaft within a preset time t. x (t);

[0127] An axial displacement determination unit is used to determine the axial displacement based on the acceleration a. x (t) and the axial displacement relationship s x (t)=∫∫a x (t) Determine the axial displacement sx(t) of the wind turbine output shaft;

[0128] The frequency determination unit 41 is specifically used to determine the blade vibration frequency and axial rotation frequency based on the axial vibration displacement spectrum formed by the axial displacement.

[0129] The frequency determination unit 41 is specifically used to determine the frequency corresponding to the maximum value of the axial displacement within the first preset frequency range of the axial vibration displacement spectrum as the axial rotation frequency.

[0130] The frequency corresponding to the maximum value of the axial displacement determined within the second preset frequency range of the axial vibration displacement spectrum is taken as the blade vibration frequency.

[0131] The first preset frequency range is defined as the average rotational frequency f of the wind turbine within a preset time period. n0 Centered on the average rotor speed f within a preset time period, the second preset frequency range is defined as follows: n0 Centered on k times the value of the blade, where k is the number of blades.

[0132] The rotational speed determination unit is used to determine the rotational speed v(t) of the wind turbine within a preset time t;

[0133] The average rotational speed determination unit is used to determine the average rotational speed within a preset time t based on the rotational speed within that preset time t.

[0134] The average rotational speed determination unit is used to determine the average rotational speed based on the relationship between the average rotational speed and the rotational speed. Determine the average rotation frequency within a preset time t.

[0135] The search range setting unit is used to set the search range △f;

[0136] Frequency determination unit 41 is specifically used to determine the frequency range f of the axial vibration displacement spectrum. a =[f n0 -△f,fn0 The frequency corresponding to the maximum value of the axial displacement within the range of +△f] is taken as the axial rotation frequency s. Zx (f nx );

[0137] In the second preset frequency range f of the axial vibration displacement spectrum b =[kf n0 -△f,kf n0 The frequency corresponding to the maximum value of the axial displacement determined within +△f] is taken as the blade vibration frequency s. Zx (f knx ).

[0138] The motion trajectory determination unit is used to determine the motion trajectory of the shaft center of the wind turbine output shaft;

[0139] The fault determination unit 42 is specifically used to determine that the wind turbine has an imbalance fault when the ratio of the axial rotation frequency to the blade vibration frequency exceeds the first threshold value and the motion trajectory of the shaft center meets the fault threshold rule.

[0140] The radial displacement acceleration determination unit is used to obtain the acceleration a of the radial horizontal displacement within a preset time t. y (t) and the acceleration a of the radial vertical displacement within the preset time t. z (t);

[0141] A radial displacement determination unit is used to determine the radial horizontal displacement based on the acceleration 'a'. y (t), radial vertical displacement acceleration az(t), radial horizontal displacement relationship s y (t)=∫∫a y (t) and the relationship between radial and vertical displacement s z (t)=∫∫a z (t) Determine the radial horizontal displacement s y (t) and radial vertical displacement sz(t);

[0142] The motion trajectory determination unit is specifically used to determine the radial horizontal displacement s. y (t) and radial vertical displacement s z (t) determines the trajectory r(t) of the axis of motion.

[0143] The amplitude ratio determination unit is used to determine the amplitude ratio s of the major axis and minor axis of the graphic formed by the motion trajectory based on the motion trajectory of the axis center. max ;

[0144] The process of determining the motion trajectory of the shaft to satisfy the fault threshold rule is as follows:

[0145] In amplitude ratio s max Not less than the preset value s kIf so, the motion trajectory is determined to satisfy the fault threshold rule.

[0146] The first condition determination unit is used to determine whether the first fault warning condition is met when the ratio of the axial rotational frequency to the blade vibration frequency exceeds a second threshold value. k When the first fault alarm condition is met, the first threshold value w is determined. k Greater than the second threshold value;

[0147] The second condition determination unit is used to determine the amplitude ratio s. max When the value is 1, the second fault warning condition is met, and the amplitude ratio s max The value is not less than the preset value s k When the second fault alarm condition is met, the preset value s is set. k Greater than 1;

[0148] The fault determination unit 42 is specifically used to determine the fault when the ratio of the axial rotational frequency to the blade vibration frequency meets the first fault warning condition or the first fault alarm condition; and the amplitude ratio s max If the conditions for the second fault warning or the second fault alarm are met, it is determined that the wind turbine has an imbalance fault.

[0149] If an imbalance fault is determined in the wind turbine, the pre-alarm level and amplitude ratio s should be determined according to the ratio of axial rotation frequency to blade vibration frequency. max The lower of the eligible early warning levels determines the level of wind turbine imbalance fault.

[0150] Figure 5 This is a schematic diagram of an online diagnostic device for wind turbine imbalance provided by the present invention. The online diagnostic device for wind turbine imbalance includes:

[0151] Memory 51 is used to store computer programs;

[0152] The processor 52 is used to implement the steps of the above-described online diagnostic method for wind turbine imbalance when executing a computer program.

[0153] Please refer to the above embodiments for a description of the online diagnostic device for wind turbine imbalance provided in this application, and it will not be repeated here.

[0154] It should also be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0155] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0156] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An online diagnostic method for wind turbine imbalance, characterized in that, include: The blade vibration frequency and axial rotation frequency in the axial vibration spectrum of the wind turbine output shaft are determined. The axial rotation frequency is positively correlated with the degree of imbalance of the wind turbine blades, and the blade vibration frequency is positively correlated with the number of blades. When the ratio of the axial rotation frequency to the blade vibration frequency exceeds a first threshold, it is determined that the wind turbine has an imbalance fault. Also includes: Determine the motion trajectory of the shaft center of the wind turbine output shaft; When the ratio of the axial rotational frequency to the blade vibration frequency exceeds a first threshold, an imbalance fault is determined in the wind turbine, including: If the ratio of the axial rotation frequency to the blade vibration frequency exceeds a first threshold and the motion trajectory of the shaft center satisfies the fault threshold rule, it is determined that the wind turbine has an imbalance fault. The process of determining whether the motion trajectory satisfies the fault threshold rule includes: The amplitude ratio of the major axis to the minor axis of the graphic formed by the motion trajectory is determined based on the motion trajectory of the axis. ; In the amplitude ratio Not less than the preset value If so, the motion trajectory is determined to satisfy the fault threshold rule; The condition that the ratio of the axial rotational frequency to the blade vibration frequency exceeds a first threshold and the motion trajectory of the shaft center satisfies the fault threshold rule determines that the wind turbine has an imbalance fault, including: When the ratio of the axial rotation frequency to the blade vibration frequency exceeds the second threshold, it is determined that the first fault warning condition is met; when the ratio of the axial rotation frequency to the blade vibration frequency exceeds the first threshold, it is determined that the first fault alarm condition is met. The first threshold is greater than the second threshold, and the first threshold and the second threshold are set according to the degree of wind turbine imbalance. In the amplitude ratio When the value is 1, the second fault warning condition is determined to be met, and the amplitude ratio is... The value is not less than the preset value. When the second fault alarm condition is met, the preset value is determined to be true. Greater than 1; The ratio of the axial rotational frequency to the blade vibration frequency meets the first fault warning condition or the first fault alarm condition; and the amplitude ratio If the second fault warning condition or the second fault alarm condition is met, it is determined that the wind turbine has an imbalance fault.

2. The online diagnostic method for wind turbine imbalance as described in claim 1, characterized in that, Determine the blade vibration frequency and axial rotational frequency in the axial vibration spectrum of the wind turbine output shaft, including: Obtain the acceleration of the axial displacement of the wind turbine output shaft within a preset time t. ; Based on the acceleration of the axial displacement and axial displacement relationship Determine the axial displacement of the wind turbine output shaft ; The blade vibration frequency and the axial rotation frequency are determined based on the axial vibration displacement spectrum formed by the axial displacement.

3. The online diagnostic method for wind turbine imbalance as described in claim 2, characterized in that, Determining the blade vibration frequency and the axial rotation frequency based on the spectrum formed by the axial displacement includes: The frequency corresponding to the maximum value of the axial displacement determined within the first preset frequency range of the axial vibration displacement spectrum is taken as the axial rotation frequency. The frequency corresponding to the maximum value of the axial displacement determined within the second preset frequency range of the axial vibration displacement spectrum is taken as the blade vibration frequency. Wherein, the first preset frequency range is the average rotational frequency of the wind turbine within the preset time period. Centered on the average rotational frequency of the wind turbine within the preset time period, the second preset frequency range is based on the average rotational frequency of the wind turbine within the preset time period. Centered on k times the value of the blades, where k is the number of blades.

4. The online diagnostic method for wind turbine imbalance as described in claim 3, characterized in that, The process of determining the average rotational frequency of the wind turbine within the preset time period includes: Determine the rotational speed of the wind turbine within a preset time t. ; The average rotational speed within the preset time t is determined based on the rotational speed within the preset time t. ; Based on the relationship between the average rotational speed and rotational frequency Determine the average rotation frequency within the preset time t.

5. The online diagnostic method for wind turbine imbalance as described in claim 3, characterized in that, Before using the frequency corresponding to the maximum value of the axial displacement within the first preset frequency range of the axial vibration displacement spectrum as the axial rotation frequency, the method further includes: Set search scope ; The frequency corresponding to the maximum value of the axial displacement determined within a first preset frequency range of the axial vibration displacement spectrum is taken as the axial rotation frequency, including: The first preset frequency range of the axial vibration displacement spectrum The frequency corresponding to the maximum value of the internally determined axial displacement is taken as the axial rotation frequency. ; The frequency corresponding to the maximum value of the axial displacement determined within the second preset frequency range of the axial vibration displacement spectrum is taken as the blade vibration frequency, including: The second preset frequency range of the axial vibration displacement spectrum The frequency corresponding to the maximum value of the internally determined axial displacement is taken as the blade vibration frequency. .

6. The online diagnostic method for wind turbine imbalance as described in claim 1, characterized in that, Determining the motion trajectory of the shaft center of the wind turbine output shaft includes: Obtain the acceleration of the radial horizontal displacement within a preset time t. and the acceleration of the radial vertical displacement within a preset time t ; Based on the acceleration of the radial horizontal displacement The acceleration of the radial vertical displacement Radial and horizontal displacement relationship and the relationship between radial and vertical displacement Determine the radial horizontal displacement and the radial vertical displacement ; According to the radial horizontal displacement and the radial vertical displacement Determine the motion trajectory of the axis. .

7. The online diagnostic method for wind turbine imbalance as described in claim 1, characterized in that, The ratio of the axial rotational frequency to the blade vibration frequency meets the first fault warning condition or the first fault alarm condition; and the amplitude ratio When the second fault warning condition or the second fault alarm condition is met, it is determined that the wind turbine has an imbalance fault, which also includes: If an imbalance fault is determined in the wind turbine, a pre-alarm level is established based on the ratio of the axial rotation frequency to the blade vibration frequency, and the amplitude ratio is also considered. The lower of the eligible pre-alarm levels determines the level of the wind turbine imbalance fault.

8. An online diagnostic system for wind turbine imbalance, characterized in that, include: The frequency determination unit is used to determine the blade vibration frequency and axial rotation frequency in the axial vibration spectrum of the wind turbine output shaft. The axial rotation frequency is positively correlated with the degree of imbalance of the wind turbine blades, and the blade vibration frequency is positively correlated with the number of blades. The fault determination unit is used to determine that the wind turbine has an imbalance fault when the ratio of the axial rotation frequency to the blade vibration frequency exceeds a first threshold value. A motion trajectory determination unit is used to determine the motion trajectory of the axis of the wind turbine output shaft; The fault determination unit is specifically used to determine that the wind turbine has an imbalance fault when the ratio of the axial rotation frequency to the blade vibration frequency exceeds a first threshold value and the motion trajectory of the shaft center meets the fault threshold rule. The amplitude ratio determination unit is used to determine the amplitude ratio of the major axis to the minor axis of the graphic formed by the motion trajectory based on the motion trajectory of the axis. ; The process of determining whether the motion trajectory satisfies the fault threshold rule includes: In the amplitude ratio Not less than the preset value If so, the motion trajectory is determined to satisfy the fault threshold rule; The first condition determination unit is used to determine that a first fault warning condition is met when the ratio of the axial rotation frequency to the blade vibration frequency exceeds a second threshold value, and to determine that a first fault alarm condition is met when the ratio of the axial rotation frequency to the blade vibration frequency exceeds the first threshold value. The first threshold value is greater than the second threshold value, and the first threshold value and the second threshold value are set according to the degree of wind turbine imbalance. The second condition determination unit is used to determine the amplitude ratio. When the value is 1, the second fault warning condition is determined to be met, and the amplitude ratio is... The value is not less than the preset value. When the second fault alarm condition is met, the preset value is determined to be true. Greater than 1; The fault determination unit is specifically used when the ratio of the axial rotational frequency to the blade vibration frequency meets the first fault warning condition or the first fault alarm condition; and the amplitude ratio If the second fault warning condition or the second fault alarm condition is met, it is determined that the wind turbine has an imbalance fault.

9. An online diagnostic device for wind turbine imbalance, characterized in that, include: Memory, used to store computer programs; A processor, configured to execute the computer program to implement the steps of the online diagnostic method for wind turbine imbalance as described in any one of claims 1 to 7.

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