Variable pitch control method and system for wind generating set and wind generating set

Abstract

The invention provides a variable pitch control method and system of a wind generating set and the wind generating set. The wind generating set comprises a variable-pitch system, and the variable-pitch system comprises blades, a variable-pitch bearing and a variable-pitch gear. The method comprises the following steps: acquiring the static friction torque of a variable pitch bearing of the wind generating set; based on the static friction torque of the variable-pitch bearing, determining the change trend of the gravity torque of the blade relative to the variable-pitch bearing in the rotating process by adopting a third-party load calculation model; and according to the change trend of the gravity torque, the azimuth angle and the pitch angle of the blade are adjusted, so that the backlash between the variable-pitch bearing and the variable-pitch gear caused by the change of the gravity torque is eliminated, and the load impact caused by backlash slipping is reduced. According to the embodiment of the invention, the backlash between the variable-pitch bearing and the variable-pitch gear can be eliminated, the risk of slipping of the variable-pitch bearing and the variable-pitch gear is reduced, safe operation of a unit is ensured, and the service life of the variable-pitch system of the wind generating set is prolonged.

Description

Technical Field

[0001] This application relates to the technical field of wind power, and particularly relates to a pitch control method and system for a wind turbine generator set, and a wind turbine generator set. Background Art

[0002] The pitch system of a wind turbine generator set is an important control actuator in a wind power system, and it includes mechanical components and electrical systems such as blades, root bolts, pitch bearings, pitch gearboxes, pitch motors, and controllers. Due to the pre-bending of the blades, when the wind turbine generator set is operating, the gravitational load of the blades will generate an alternating torque on the pitch bearing. When the alternating torque load changes direction and its amplitude is less than the static friction torque of the pitch bearing, the pitch motor is unloaded, and the backlash of the pitch transmission mechanism will remain at the force application end (i.e., the load transfer path end). When the amplitude of the alternating torque load changes exceeds the static friction torque of the pitch bearing, the phenomenon of backlash slip will occur. This phenomenon will cause components such as the pitch motor, pitch bearing, and root bolts to bear impact loads. Moreover, if the frequency conversion motor is driving for pitch adjustment, its operating frequency will dynamically change between 0 Hz and 200 Hz. Under the impact load of backlash slip, if the operating frequency overlaps with the modal frequency (sometimes also called the solid frequency) of the pitch mechanical system, the impact load on components such as the pitch motor, pitch bearing, and root bolts will increase when the overlap occurs. Under the long-term action of these two impact loads, in the lightest case, it may cause wear on the tooth surface of the pitch bearing of the pitch system, and in the worst case, it may cause serious device damage such as root bolt fracture and pitch bearing damage, and even production accidents, causing significant economic losses to the enterprise. Therefore, there is an urgent need to provide a pitch control method for a wind turbine generator set in order to solve the above problems. Summary of the Invention

[0003] In view of at least one of the above technical problems existing in the prior art, this application is proposed. According to one aspect of this application, a pitch control method for a wind turbine generator set is provided. The wind turbine generator set includes a pitch system, and the pitch system includes blades, a pitch bearing, and a pitch gear. The method includes:

[0004] Obtain the static friction torque of the pitch bearing of the wind turbine generator set;

[0005] Based on the static friction torque of the pitch bearing, use a third-party load calculation model to determine the change trend of the gravitational torque of the blade relative to the pitch bearing during rotation;

[0006] According to the change trend of the gravitational torque, adjust the azimuth angle and pitch angle of the blade to eliminate the backlash between the pitch bearing and the pitch gear caused by the change of the gravitational torque, and reduce the load impact caused by backlash slip.

[0007] In some embodiments, the pitch system further includes a variable-frequency motor; the method further includes:

[0008] Performing a dynamic analysis on the pitch system to determine the modal frequency of the pitch system;

[0009] Obtaining the dynamic operating frequency of the variable-frequency motor;

[0010] Determining whether there is a resonance intersection point between the modal frequency of the pitch system and the dynamic operating frequency of the variable-frequency motor;

[0011] In the case where there is a resonance intersection point between the modal frequency of the pitch system and the dynamic operating frequency of the variable-frequency motor, adjusting the dynamic operating frequency of the variable-frequency motor so that the dynamic operating frequency quickly crosses the modal frequency, and reducing the load impact caused by frequency resonance.

[0012] In some embodiments, performing a dynamic analysis on the pitch system to determine the modal frequency of the pitch system includes:

[0013] Performing a dynamic analysis on the pitch system according to the pitch parameters of the pitch system respectively when the blade is fixed and rotating, to determine the modal frequency of the pitch system;

[0014] Wherein, the pitch parameters of the pitch system at least include the rotor inertia of the motor, the inertia of the gear train of the speed reducer, the inertia of the pinion, the inertia of the bearing, the stiffness of the high-speed end of the speed reducer, the stiffness of the low-speed end of the speed reducer, the damping of the high-speed end of the speed reducer, the damping of the low-speed end of the speed reducer, the speed ratio of the speed reducer, and the speed ratio of the gear ring.

[0015] In some embodiments, based on the static frictional torque of the pitch bearing, using a third-party load calculation model to determine the change trend of the gravitational torque of the blade relative to the pitch bearing during rotation includes:

[0016] According to the third-party load calculation model, simulating and calculating at least two sets of gravitational torques and the static frictional torque of the pitch bearing under different working conditions;

[0017] Based on the magnitude relationship between the gravitational torque and the static frictional torque of the pitch bearing, determining the change trend of the gravitational torque of the blade relative to the pitch bearing during rotation.

[0018] In some embodiments, according to the third-party load calculation model, simulating and calculating at least two sets of gravitational torques and the static frictional torque of the pitch bearing under different working conditions includes:

[0019] Under power generation and idling conditions respectively, calculate the at least two sets of gravity torques and the static friction torque of the pitch bearing based on a preset turbulence intensity and a preset simulation duration.

[0020] In some embodiments, according to the change trend of the gravity torque, adjust the azimuth angle and pitch angle of the blade to eliminate the backlash between the pitch bearing and the pitch gear caused by the change of the gravity torque, and reduce the load impact caused by backlash slip, including:

[0021] When the change trend of the gravity torque indicates that the gravity torque is in an increasing state relative to the static friction torque of the pitch bearing, increase or decrease the pitch angle of the blade by a preset amplitude until the backlash between the pitch bearing and the pitch gear caused by the change of the gravity torque is eliminated.

[0022] In some embodiments, when the change trend of the gravity torque indicates that the gravity torque is in an increasing state relative to the static friction torque of the pitch bearing, increase or decrease the pitch angle of the blade by a preset amplitude until the backlash between the pitch bearing and the pitch gear caused by the change of the gravity torque is eliminated, including:

[0023] When the azimuth angle of the blade is within the first azimuth angle range, increase the pitch angle of the blade based on a preset amplitude;

[0024] Judge whether the gravity torque is still greater than the static friction torque of the pitch bearing after increasing the pitch angle of the blade;

[0025] When the gravity torque is still greater than the static friction torque of the pitch bearing, continue to increase the pitch angle of the blade by a preset amplitude; otherwise, stop increasing the pitch angle of the blade.

[0026] In some embodiments, when the change trend of the gravity torque indicates that the gravity torque is in an increasing state relative to the static friction torque of the pitch bearing, increase or decrease the pitch angle of the blade by a preset amplitude until the backlash between the pitch bearing and the pitch gear caused by the change of the gravity torque is eliminated, including:

[0027] When the azimuth angle of the blade is within the second azimuth angle range, decrease the pitch angle of the blade based on a preset amplitude;

[0028] Judge whether the gravity torque is still greater than the static friction torque of the pitch bearing after decreasing the pitch angle of the blade;

[0029] When the gravity torque is still greater than the static friction torque of the pitch bearing, continue to decrease the pitch angle of the blade by the preset amplitude; otherwise, stop decreasing the pitch angle of the blade.

[0030] Another aspect of the embodiment of the present application provides a pitch control system for a wind turbine generator set, the system comprising:

[0031] A memory and a processor, wherein a computer program run by the processor is stored on the memory, and when the computer program is run by the processor, the processor is made to execute the pitch control method of the wind turbine generator set as described above.

[0032] Another aspect of the embodiment of the present application provides a wind turbine generator set, the wind turbine generator set comprising the pitch control system of the wind turbine generator set as described above.

[0033] In the pitch control method of the wind turbine generator set according to the embodiment of the present application, through the static friction torque calculation formula of the pitch bearing of the wind turbine generator set, a third-party load calculation model is adopted to determine the change trend of the gravity torque of the blade relative to the pitch axis, and according to the change trend, the pitch angle of the blade is adjusted to eliminate the backlash at the load transfer force receiving end of the gravity torque. In the embodiment of the present application, when there is a risk of slipping in the wind turbine generator set, the pitch angle of the blade can be adjusted in advance, so as to eliminate the backlash of the pitch system, thereby ensuring the safe operation of the unit, increasing the service life of the pitch system of the wind turbine generator set, and reducing the failure rate of the wind turbine generator set; the embodiment of the present application does not need to increase or transform the hardware cost of the wind turbine generator set, and only adjusts according to the on-site operation data, which is easy to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present application, and those of ordinary skill in the art can also obtain other drawings based on these drawings without creative efforts.

[0035] Figure 1 A schematic flow chart showing the pitch control method of the wind turbine generator set according to the embodiment of the present application;

[0036] Figure 2 A schematic flow chart showing step S102 according to the embodiment of the present application;

[0037] Figure 3 A schematic flow chart showing step S201 according to the embodiment of the present application;

[0038] Figure 4 A schematic flow chart showing step S103 according to the embodiment of the present application;

[0039] Figure 5Shows a schematic flowchart of step S401 according to an embodiment of the present application;

[0040] Figure 6 Shows a schematic flowchart of step S402 according to an embodiment of the present application;

[0041] Figure 7 Shows a schematic flowchart of a pitch control method for a wind turbine according to another embodiment of the present application;

[0042] Figure 8 Shows a schematic diagram of a pitch system dynamics analysis model according to an embodiment of the present application;

[0043] Figure 9 Shows a schematic flowchart of step S701 according to an embodiment of the present application;

[0044] Figure 10 Shows a schematic block diagram of a pitch control system for a wind turbine according to an embodiment of the present application;

[0045] Figure 11 Shows a schematic block diagram of a wind turbine according to an embodiment of the present application. Detailed implementation manners

[0046] To enable those skilled in the art to better understand the technical solutions of the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0047] Some noun definitions related to wind turbines in the embodiments of the present application are as follows:

[0048] The pitch angle is the angle between the wind turbine blade and the rotation plane, mainly used to adjust the aerodynamic performance of the blade. For example, during wind power generation, by adjusting the pitch angle, the aerodynamic angle of attack of the blade can be changed, thereby controlling the wind energy capture efficiency.

[0049] The azimuth angle is the circumferential position where the blade is located during rotation (for example, with the rotation center as the origin, 0° to 360° represents the direction where the blade is located). During wind power generation, the change in the azimuth angle directly affects the relative movement direction between the blade and the airflow.

[0050] Based on the foregoing at least one technical problem, the present application provides a pitch control method for a wind turbine generator set, and the method includes: obtaining a calculation formula and coefficients of the static friction torque of the pitch bearing of the wind turbine generator set; according to the calculation formula and coefficients of the static friction torque of the pitch bearing, using a third-party load calculation model to determine the change trend of the gravity torque of the blade relative to the pitch axis; according to the change trend, adjusting the pitch angle of the blade to eliminate the backlash at the load transfer force receiving end of the gravity torque. In the pitch control method for a wind turbine generator set according to the embodiment of the present application, through the calculation formula and coefficients of the static friction torque of the pitch bearing of the wind turbine generator set, a third-party load calculation model is used to determine the change trend of the gravity torque of the blade relative to the pitch axis, and according to the change trend, the pitch angle of the blade is adjusted to eliminate the backlash at the load transfer force receiving end of the gravity torque. In the embodiment of the present application, when there is a slipping risk in the wind turbine generator set, the pitch angle of the blade can be adjusted in advance, so as to eliminate the backlash of the pitch system, thereby ensuring the safe operation of the unit, increasing the service life of the pitch system of the wind turbine generator set, and reducing the failure rate of the wind turbine generator set; the embodiment of the present application does not need to increase or transform the hardware cost of the wind turbine generator set, and only adjusts according to the on-site operation data, which is easy to implement.

[0051] Figure 1 FIG. shows a schematic flow chart of a pitch control method for a wind turbine generator set according to an embodiment of the present application; as Figure 1 shown, the pitch control method 100 for a wind turbine generator set according to an embodiment of the present application may include the following steps S101, step S102, and step S103:

[0052] In step S101, obtain the static friction torque of the pitch bearing of the wind turbine generator set.

[0053] In one example, a pre-designed calculation formula may be used to calculate the calculation formula and coefficients of the static friction torque of the pitch bearing. For example, it may be calculated according to the calculation formula of the static friction torque of the pitch bearing in the traditional technology. In the traditional technology, the basic calculation formula of the static friction torque of the pitch bearing is:

[0054] M = F × r,

[0055] F = μp,

[0056] wherein, F represents the frictional force; r represents the bearing radius; μ represents the friction coefficient; p represents the load.

[0057] In other examples, for a wind turbine generator set, since the static friction torque of the pitch bearing is relatively fixed, therefore, the static friction torque and coefficients provided by the supplier may also be directly used as the input of the subsequent load calculation model.

[0058] In step S102, based on the static friction torque of the pitch bearing, a third-party load calculation model is used to determine the change trend of the gravity torque of the blade relative to the pitch bearing during rotation.

[0059] Among them, the third-party load calculation model shall meet the design requirements of Part 1 of "IEC 61400-1 Wind Energy Generation Systems" (4.0 Edition, 2019). For offshore wind turbines, it shall also meet the design requirements of Part 3-1 "Fixed Offshore Wind Turbines" of "IEC 61400-3-1 Wind Energy Generation System Specification" (1st Edition, 2019-04).

[0060] In an embodiment of the present application, as Figure 2 shown, the step S102 of determining the change trend of the gravity torque of the blade relative to the pitch bearing based on the static friction torque of the pitch bearing by using a third-party load calculation model includes step S201 and step S202:

[0061] In step S201, according to the third-party load calculation model, at least two sets of gravity torques and the static friction torque of the pitch bearing under different working conditions are simulated and calculated;

[0062] In step S202, based on the magnitude relationship between the gravity torque and the static friction torque of the pitch bearing, the change trend of the gravity torque of the blade relative to the pitch bearing during rotation is determined.

[0063] Generally, when the gravity torque is greater than the static friction torque of the pitch bearing, the backlash between the pitch bearing and the pitch gear increases, and there is a risk of slipping. Before a slipping event may occur, the change trend of the gravity torque can be predicted, and the gravity torque can be adjusted in time according to the change trend of the gravity torque, thereby reducing the slipping risk.

[0064] In an embodiment of the present application, as Figure 3 shown, step S201 of simulating and calculating at least two sets of gravity torques and the static friction torque of the pitch bearing under different working conditions according to the third-party load calculation model includes step S301:

[0065] In step S301, under the conditions of power generation and idling working conditions respectively, at least two sets of gravity torques and the static friction torque of the pitch bearing are calculated based on a preset turbulence intensity and a preset simulation duration.

[0066] For example, assume that the preset turbulence intensity is 6% and the preset simulation duration is 10 minutes. Under the conditions of power generation and idling operating conditions respectively, data of multiple groups of gravitational torques and static frictional torques of the pitch bearings can be calculated. Then, the gravitational torques and the static frictional torques of the pitch bearings in each group of data are compared. Since there is a risk of gear slippage when the gravitational torque is greater than the static frictional torque of the pitch bearing, the gravitational torque can be adjusted before a slippage event may occur, thereby reducing the slippage risk.

[0067] In step S103, according to the change trend of the gravitational torque, the azimuth angle and the pitch angle of the blade are adjusted to eliminate the backlash between the pitch bearing and the pitch gear caused by the change of the gravitational torque, and reduce the load impact caused by backlash slippage.

[0068] In an embodiment of the present application, in an embodiment of the present application, as Figure 4 shown, according to the change trend of the gravitational torque, the azimuth angle and the pitch angle of the blade are adjusted to eliminate the backlash between the pitch bearing and the pitch gear caused by the change of the gravitational torque, and reduce the load impact caused by backlash slippage, including step S401:

[0069] In step S401, when the change trend of the gravitational torque indicates that the gravitational torque is in an increasing state relative to the static frictional torque of the pitch bearing, the pitch angle of the blade is increased or decreased by a preset amplitude until the backlash between the pitch bearing and the pitch gear caused by the change of the gravitational torque is eliminated.

[0070] Since there is a corresponding relationship between the slippage event and the azimuth angle of the blade when slippage occurs, there is a corresponding relationship between the azimuth angle of the blade and the pitch angle of the blade, and there is also a corresponding relationship between the pitch angle of the blade and the gravitational torque. Therefore, by adjusting the azimuth angle of the blade or the pitch angle of the blade, the gravitational torque can be adjusted, so as to achieve the purpose of avoiding the occurrence of slippage events.

[0071] From another perspective, during the operation of a wind turbine generator set, an excessively small azimuth angle of the blade may cause local stress concentration and trigger slippage. Therefore, if the minimum azimuth angle and the maximum azimuth angle (the maximum azimuth angle at which the control strategy is activated) when slippage occurs can be determined, when the blade is about to reach the minimum azimuth angle, or rather, when the azimuth angle of the blade is at the maximum azimuth angle at which the control strategy is activated, an intervention measure (for example, adjusting the pitch angle of the blade) is initiated to avoid a slippage event caused by local stress concentration. The minimum azimuth angle when slippage occurs refers to the minimum threshold of the azimuth angle corresponding to the blade when the pitch system starts to experience slippage, which is usually determined by friction conditions, load distribution, and mechanical structure stability. At the same time, in order to be able to adjust the pitch angle of the blade in advance, the maximum azimuth angle at which the control strategy is activated should be less than the minimum azimuth angle and the maximum azimuth angle when slippage occurs by a certain degree.

[0072] In some examples, the correspondence between the minimum azimuth angle when slippage occurs and the maximum azimuth angle at which the control strategy is activated is shown in Table 1.

[0073] Table 1: Correspondence table of the minimum azimuth angle when slippage occurs and the maximum azimuth angle at which the control strategy is activated

[0074]

[0075] As can be seen from Table 1, when the determined minimum azimuth angle when slippage occurs is greater than or equal to 45 degrees, the blade pitch angle should be adjusted when the blade actually reaches 30 degrees to avoid slippage; when the determined minimum azimuth angle when slippage occurs is 37 degrees, the blade pitch angle should be adjusted when the blade actually reaches 22 degrees to avoid slippage. That is to say, the minimum azimuth angle when slippage occurs should be approximately 15 degrees different from the maximum azimuth angle at which the control strategy is activated.

[0076] Based on the statistically obtained information of the minimum azimuth angle when slippage occurs, the maximum blade azimuth angle at which the pitch angle adjustment strategy is activated after the blade rotates past the vertical plane can be determined. The preset amplitude of the pitch angle to be adjusted each time can be set to 1 degree, and its adjustment direction is opposite to the possible slippage direction. The basic principle is to eliminate the backlash at the force-bearing end of the pitch gear system before the gravitational torque value of the pre-bent blade on the pitch axis becomes larger to avoid harmful slippage.

[0077] In one example, as Figure 5 shown, in the case where the change trend of the gravitational torque indicates that the gravitational torque is in an increasing state relative to the static friction torque of the pitch bearing, increasing or decreasing the pitch angle of the blade by a preset amplitude until the backlash between the pitch bearing and the pitch gear caused by the change in the gravitational torque is eliminated includes steps S501, step S502, step S503, and step S505:

[0078] In step S501, when the azimuth angle of the blade is within the first azimuth angle range, increase the pitch angle of the blade based on the preset amplitude;

[0079] In step S502, determine whether the gravitational torque is still greater than the static friction torque of the pitch bearing after increasing the pitch angle of the blade; if so, execute step S503; otherwise, execute step S504;

[0080] In step S503, continue to increase the pitch angle of the blade by the preset amplitude;

[0081] In step S504, stop increasing the pitch angle of the blade.

[0082] For example, the first azimuth range is from 0 degrees to 30 degrees, and the preset amplitude of the pitch angle is 1 degree. Of course, the preset amplitude of the pitch angle can also be set to 0.5 - 1.5 degrees. The embodiments of the present application are only used as examples to illustrate the inventive concept of the present application, and do not limit the protection scope of the present invention.

[0083] In another example, as Figure 6 shown, in step S401, when the change trend of the gravitational torque indicates that the gravitational torque is in an increasing state relative to the static friction torque of the pitch bearing, increasing or decreasing the pitch angle of the blade by a preset amplitude until the backlash between the pitch bearing and the pitch gear caused by the change in the gravitational torque is eliminated, includes steps S601, step S602, step S603, and step S604:

[0084] In step S601, when the azimuth angle of the blade is within the second azimuth range, reducing the pitch angle of the blade based on the preset amplitude;

[0085] In step S602, determining whether the gravitational torque is still greater than the static friction torque of the pitch bearing after reducing the pitch angle of the blade; if so, executing step S504; otherwise, executing step S505;

[0086] In step S603, continuously reducing the pitch angle of the blade by the preset amplitude;

[0087] In step S604, stopping reducing the pitch angle of the blade.

[0088] For example, the second azimuth range is from 180 degrees to 210 degrees, and the preset amplitude of the pitch angle is 1 degree. Of course, the preset amplitude of the pitch angle can also be adjusted to 0.5 - 1.5 degrees. The embodiments of the present application are only used as examples to illustrate the inventive concept of the present application, and do not limit the protection scope of the present invention.

[0089] It should be noted that the preset amplitudes of the two pitch angle adjustments can be the same or different.

[0090] For example, assuming that when a person faces the wind turbine, the impeller rotates clockwise, and the azimuth angle when the blade is directly above the tower barrel is 0 degrees; when the blade rotates to the 90 - degree azimuth angle, the blade is at the 3 o'clock direction; when the blade rotates to the 180 - degree azimuth angle, the blade is at the 6 o'clock direction; when the blade rotates to the 270 - degree azimuth angle, the blade is at the 9 o'clock direction.

[0091] When the blade is at the azimuth angle of 90 degrees, the gravitational torque and the aerodynamic torque are in the same direction, causing the pitch angle to become smaller; when the blade is at the azimuth angle of 270 degrees, the gravitational torque and the aerodynamic torque are in the opposite direction, and the gravitational torque causes the pitch angle to become larger. At the two azimuth angles of 90 degrees and 270 degrees, the impact of backlash slip on the pitch system is the greatest, and at the two azimuth angles of 0 degrees and 180 degrees, the impact of backlash slip on the pitch system is the smallest.

[0092] Based on the above analysis, the preset amplitude of the pitch angle can be set to 1 degree. When the azimuth angle of the blade changes from 0 degrees to 90 degrees, the pitch angle is adjusted to increase by 1 degree each time. When the blade rotates from 180 degrees to 270 degrees, the pitch angle is adjusted to decrease by 1 degree each time.

[0093] Generally speaking, in the embodiment of the present application, to avoid backlash slip of the pitch system of the wind turbine generator, when the azimuth angle of the blade is between 0 degrees and 30 degrees, the pitch angle is adjusted to increase by 0.5 - 1.5 degrees; when the azimuth angle of the blade is between 180 degrees and 210 degrees, the pitch angle is adjusted to decrease by 0.5 - 1.5 degrees. By this method, the backlash of the pitch system is eliminated, and the impact load caused by backlash slip on the pitch system is avoided.

[0094] Further, analyze whether the current or torque of the pitch motor mutates when the azimuth angle of the blade is in the range of plus or minus 60 degrees of 90 degrees and 270 degrees, and adjust the starting amplitude of the pitch angle and the maximum azimuth angle for starting the control strategy in the control strategy accordingly to eliminate the mutation of the current or torque. An example of the adjustment process is as follows: if there is a mutation and the mutation azimuth angle is close to 90 degrees or 270 degrees, the pitch angle is increased according to the preset amplitude. For example, it is increased by 0.5 degrees each time, and then the changes in the current or torque of the pitch motor before and after the increase are compared to determine the final starting angle of the pitch angle and the maximum azimuth angle for starting the control strategy. In this way, the adjustment and verification of the control strategy can be realized, and the purpose of effectively avoiding harmful slip can be achieved.

[0095] In another embodiment of the present application, the pitch system further includes a variable-frequency motor. As Figure 7 shown, the method further includes step S701, step S702, and step S703:

[0096] In step S701, perform a dynamic analysis on the pitch system to determine the modal frequency of the pitch system;

[0097] In step S702, obtain the dynamic operating frequency of the variable-frequency motor;

[0098] In step S703, determine whether there is a resonance intersection point between the modal frequency of the pitch system and the dynamic operating frequency of the variable-frequency motor; if so, execute step S704; otherwise, end this process;

[0099] In step S704, adjust the dynamic operating frequency of the variable-frequency motor so that the dynamic operating frequency quickly crosses the modal frequency, reducing the load impact caused by frequency resonance.

[0100] In the embodiment of the present application, the role of performing dynamic analysis on the pitch system is to analyze the dynamic response of the pitch system under excitation to determine the modal frequency (natural frequency).

[0101] As Figure 8 shown, it is a schematic diagram of the pitch system dynamic analysis model 800. Generally, the pitch system dynamic analysis model includes two types:

[0102] The first type is to establish a model including the motor rotor, reduction gearbox, and output pinion according to the pitch system parameters with the blade fixed. Combining Figure 8 , where the bearing is fixed and the pinion is fixed. Modal analysis can be performed based on parameters such as the damping at the low-speed end of the reduction gearbox, the damping at the high-speed end of the reduction gearbox, the stiffness at the low-speed end of the reduction gearbox, the stiffness at the high-speed end of the reduction gearbox, the moment of inertia of the motor rotor, the moment of inertia of the reduction gearbox gear train, the moment of inertia of the pinion, the moment of inertia of the bearing, the reduction gearbox ratio, and the ring gear ratio to obtain the modal frequency (natural frequency) and vibration mode of the pitch system.

[0103] The second type is to establish a model including the blade, motor rotor, reduction gearbox, and output pinion according to the pitch system parameters with the blade rotating, and continue to combine Figure 8 , where the bearing is fixed and the pinion rotates freely. Modal analysis can be performed based on parameters such as the damping at the low-speed end of the reduction gearbox, the damping at the high-speed end of the reduction gearbox, the stiffness at the low-speed end of the reduction gearbox, the stiffness at the high-speed end of the reduction gearbox, the moment of inertia of the motor rotor, the moment of inertia of the reduction gearbox gear train, the moment of inertia of the pinion, the moment of inertia of the bearing, the reduction gearbox ratio, and the ring gear ratio to obtain the modal frequency (natural frequency) and vibration mode of the pitch system.

[0104] In one example, as Figure 9 shown, performing dynamic analysis on the pitch system in step S701 to determine the modal frequency of the pitch system includes step S901:

[0105] In step S901, respectively perform dynamic analysis on the pitch system according to the pitch parameters of the pitch system with the blade fixed and rotating to determine the modal frequency of the pitch system.

[0106] Among them, the pitch parameters of the pitch system at least include the moment of inertia of the motor rotor, the moment of inertia of the reduction gearbox gear train, the moment of inertia of the pinion, the moment of inertia of the bearing, the stiffness at the high-speed end of the reduction gearbox, the stiffness at the low-speed end of the reduction gearbox, the damping at the high-speed end of the reduction gearbox, the damping at the low-speed end of the reduction gearbox, the reduction gearbox ratio, and the ring gear ratio.

[0107] In an embodiment of the present application, by comparing the structural mode of the pitch system with the operating frequency of the pitch motor, it is determined whether there is a resonance intersection point between the pitch system and the variable-frequency motor. If there is a resonance focus, the operating frequency of the variable-frequency motor is controlled so that when the variable-frequency motor operates with variable frequency, it quickly passes through the resonance point to avoid resonance.

[0108] For example, after calculating the resonance frequency of the resonance intersection point, when the variable-frequency motor reaches the resonance frequency, its operating frequency is quickly changed to quickly pass through the resonance frequency. And after the variable-frequency motor quickly passes through the resonance frequency, it quickly resumes the normal operating frequency.

[0109] If the variable-frequency motor is used for pitch drive, its variable-frequency operating range can be from 0 Hz to 200 Hz. Under the impact load of backlash slip, the operating frequency of the variable-frequency motor will change dynamically. If its operating frequency overlaps with the modal frequency of the pitch system, it will increase the impact load on the bearing. Under long-term action, in the lightest case, it may cause wear of the bearing tooth surface, and in the most serious case, it may cause serious accidents such as breakage of the blade root bolts and damage to the pitch bearing, causing significant economic losses to the enterprise.

[0110] In an embodiment of the present application, by comparing whether there is a risk of resonance between the modal frequency of the pitch system and the operating frequency of the variable-frequency motor, the operating frequency of the variable-frequency motor is controlled. At the same time, the torque of the pitch motor in the operating data of the wind turbine generator set is analyzed to continuously adjust the size of the pitch angle by controlling the blade azimuth angle to eliminate the backlash of the pitch system. This method is simple to implement, low in cost and effective.

[0111] The following is combined with Figure 10 The pitch control system of the wind turbine generator set of the present application is described, wherein Figure 10 Fig. shows a schematic block diagram of a pitch control system of a wind turbine generator set according to an embodiment of the present application.

[0112] As Figure 10 shown, the pitch control system 1000 of the wind turbine generator set includes: one or more memories 1001 and one or more processors 1002. A computer program is stored on the memory 1001 and is run by the processor 1002. When the computer program is run by the processor 1002, the processor 1002 is caused to execute the pitch control method of the wind turbine generator set described above.

[0113] The pitch control system 1000 of the wind turbine generator set may be part or all of a computer device that can implement the pitch control method of the wind turbine generator set by software, hardware or a combination of software and hardware.

[0114] As Figure 10As shown, the pitch control system 1000 of a wind turbine generator includes one or more memories 1001, one or more processors 1002, a display (not shown), a communication interface, etc. These components are interconnected through a bus system and / or other forms of connection mechanisms (not shown). It should be noted that Figure 10 The components and structures of the pitch control system 1000 of the wind turbine generator shown are exemplary rather than restrictive. According to requirements, the pitch control system 1000 of the wind turbine generator may also have other components and structures.

[0115] The memory 1001 is used to store various data and executable program instructions generated during the operation of the relevant method. It may include one or more computer program products, and the computer program products may include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. The volatile memory may include, for example, random access memory (RAM) and / or cache memory, etc. The non-volatile memory may include, for example, read-only memory (ROM), hard disk, flash memory, etc.

[0116] The processor 1002 may be a central processing unit (CPU), an image processing unit (GPU), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other forms of processing units with data processing capabilities and / or instruction execution capabilities, and may be other components in the pitch control system 1000 of the wind turbine generator to perform desired functions.

[0117] The communication interface may be an interface of any currently known communication protocol, such as a wired interface or a wireless interface. Among them, the communication interface may include one or more serial ports, USB interfaces, Ethernet ports, WiFi, wired networks, DVI interfaces, device integrated interconnection modules, or other suitable various ports, interfaces, or connections.

[0118] In addition, according to the embodiments of the present application, as Figure 11 shown, a wind turbine generator 1100 is also provided. The wind turbine generator 1100 includes the pitch control system 1000 of the wind turbine generator as described above.

[0119] The pitch control system of the wind turbine generator and the wind turbine generator in the embodiments of the present application have the same advantages as the aforementioned pitch control method of the wind turbine generator because they can implement the aforementioned pitch control method of the wind turbine generator.

[0120] Although example embodiments have been described herein with reference to the accompanying drawings, it should be understood that the above example embodiments are merely exemplary and are not intended to limit the scope of the present application thereto. Those of ordinary skill in the art can make various changes and modifications therein without departing from the scope and spirit of the present application. All such changes and modifications are intended to be included within the scope of the present application as claimed in the appended claims.

[0121] Those of ordinary skill in the art can realize that the units and algorithm steps of the examples described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. A professional technician can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present application.

[0122] In several embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the units is only a logical function division, and there can be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another device, or some features can be ignored or not executed.

[0123] In the specification provided herein, a large number of specific details are set forth. However, it can be understood that the embodiments of the present application can be practiced without these specific details. In some instances, well-known methods, structures, and technologies are not shown in detail so as not to obscure the understanding of this specification.

[0124] Similarly, it should be understood that, in order to streamline the present application and assist in understanding one or more of the various inventive aspects, in the description of the exemplary embodiments of the present application, the various features of the present application are sometimes grouped together into a single embodiment, figure, or description thereof. However, the method of the present application should not be construed as reflecting the intention that the claimed present application requires more features than are expressly recited in each claim. Rather, as reflected by the corresponding claims, the inventive point lies in being able to solve the corresponding technical problem with fewer features than all the features of a single disclosed embodiment. Therefore, the claims following the detailed description are hereby expressly incorporated into the detailed description, where each claim itself serves as a separate embodiment of the present application.

[0125] Those skilled in the art will appreciate that, except where features are mutually exclusive, any combination can be used to combine all the features disclosed in this specification (including the accompanying claims, abstract, and drawings), as well as all the processes or units of any method or device so disclosed. Unless otherwise explicitly stated, each feature disclosed in this specification (including the accompanying claims, abstract, and drawings) can be replaced by an alternative feature that provides the same, equivalent, or similar purpose.

[0126] In addition, those skilled in the art will understand that although some of the embodiments described herein include certain features included in other embodiments rather than other features, the combination of features of different embodiments is within the scope of this application and forms different embodiments. For example, in the claims, any one of the claimed embodiments can be used in any combination.

[0127] Each component embodiment of this application can be implemented in hardware, or in software modules running on one or more processors, or in a combination thereof. Those skilled in the art should understand that a microprocessor or a digital signal processor (DSP) can be used in practice to implement some or all of the functions of some of the modules according to the embodiments of this application. This application can also be implemented as a device program (e.g., a computer program and a computer program product) for executing part or all of the methods described herein. Such a program implementing this application can be stored on a computer-readable medium, or can be in the form of one or more signals. Such signals can be downloaded from an Internet website, or provided on a carrier signal, or provided in any other form.

[0128] It should be noted that the above embodiments illustrate this application rather than limit this application, and those skilled in the art can design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps not listed in the claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. This application can be implemented by means of hardware including several different elements and by means of a suitably programmed computer. In the unit claims listing several devices, several of these devices can be embodied by the same item of hardware. The use of the words first, second, and third, etc. does not denote any order. These words can be interpreted as names.

[0129] As described above, it is only the specific implementation manner of this application or the description of the specific implementation manner. The protection scope of this application is not limited thereto. Any person skilled in the art in the technical field disclosed by this application can easily think of changes or substitutions, which should all be covered within the protection scope of this application. The protection scope of this application shall be subject to the protection scope of the claims.

Claims

1. A wind turbine generator set pitch control method, characterized in that: The wind turbine generator set includes a pitch system, and the pitch system includes blades, a pitch bearing and a pitch gear; the method includes: Obtaining the static friction torque of the variable pitch bearing of the wind turbine generator set; Based on the static friction torque of the pitch bearing, a third-party load calculation model is used to determine a change trend of the gravity torque of the blade relative to the pitch bearing during rotation; According to the variation trend of the gravity torque, the azimuth angle and the pitch angle of the blade are adjusted to eliminate the backlash between the variable pitch bearing and the variable pitch gear caused by the variation of the gravity torque, and reduce the load impact caused by backlash slippage.

2. The method according to claim 1, characterized in that The pitch system further includes a variable frequency motor; and the method further includes: Performing a dynamic analysis on the pitch system to determine a modal frequency of the pitch system; Obtaining the dynamic operating frequency of the variable frequency motor; Determining whether there is a resonance intersection between the modal frequency of the variable pitch system and the dynamic operating frequency of the variable frequency motor; When there is a resonance intersection between the modal frequency of the variable pitch system and the dynamic operating frequency of the variable frequency motor, the dynamic operating frequency of the variable frequency motor is adjusted so that the dynamic operating frequency quickly passes through the modal frequency, thereby reducing the load impact caused by frequency resonance.

3. The method according to claim 2, characterized in that Performing a dynamic analysis on the pitch system to determine the modal frequency of the pitch system includes: Under the conditions that the blade is fixed and rotating, respectively, the pitch system is dynamically analyzed according to the pitch parameters of the pitch system to determine the modal frequency of the pitch system; Among them, the pitch parameters of the pitch system include at least the motor rotor moment of inertia, the gearbox gear system moment of inertia, the pinion moment of inertia, the bearing moment of inertia, the gearbox high-speed end stiffness, the gearbox low-speed end stiffness, the gearbox high-speed end damping, the gearbox low-speed end damping, the gearbox speed ratio and the gear ring speed ratio.

4. The method according to claim 1, characterized in that: Based on the static friction torque of the pitch bearing, a third-party load calculation model is used to determine a change trend of the gravity torque of the blade relative to the pitch bearing during the rotation process, including: According to the third-party load calculation model, at least two groups of gravity torques and static friction torques of the variable pitch bearing under different working conditions are simulated and calculated; Based on the magnitude relationship between the gravity torque and the static friction torque of the pitch bearing, a change trend of the gravity torque of the blade relative to the pitch bearing during rotation is determined.

5. The method according to claim 4, characterized in that According to the third-party load calculation model, at least two groups of gravity torques and static friction torques of the pitch bearing under different working conditions are simulated and calculated, including: Under power generation and idling conditions respectively, the at least two groups of gravity torques and the static friction torque of the variable pitch bearing are calculated based on a preset turbulence intensity and a preset simulation duration.

6. The method according to claim 5, characterized in that According to the change trend of the gravity torque, the azimuth angle and the pitch angle of the blade are adjusted to eliminate the backlash between the variable pitch bearing and the variable pitch gear caused by the change of the gravity torque and reduce the load impact caused by backlash slippage, including: When the changing trend of the gravity torque indicates that the gravity torque is in an increasing state relative to the static friction torque of the pitch bearing, the pitch angle of the blade is increased or decreased by a preset amplitude until the tooth clearance between the pitch bearing and the pitch gear caused by the change of the gravity torque is eliminated.

7. The method according to claim 6, characterized in that When the change trend of the gravity torque indicates that the gravity torque is in an increasing state relative to the static friction torque of the pitch bearing, the pitch angle of the blade is increased or decreased by a preset amplitude until the backlash between the pitch bearing and the pitch gear caused by the change of the gravity torque is eliminated, including: When the azimuth angle of the blade is within a first azimuth angle range, increasing the blade pitch angle based on a preset amplitude; Determining whether the gravity torque is still greater than the static friction torque of the pitch bearing after increasing the blade pitch angle; When the gravity torque is still greater than the static friction torque of the pitch bearing, the blade pitch angle continues to be increased according to the preset amplitude; otherwise, the blade pitch angle is stopped from being increased.

8. The method according to claim 6, characterized in that When the change trend of the gravity torque indicates that the gravity torque is in an increasing state relative to the static friction torque of the pitch bearing, the pitch angle of the blade is increased or decreased by a preset amplitude until the backlash between the pitch bearing and the pitch gear caused by the change of the gravity torque is eliminated, including: When the azimuth angle of the blade is within a second azimuth angle range, reducing the blade pitch angle based on a preset amplitude; Determining whether the gravity torque is still greater than the static friction torque of the pitch bearing after reducing the blade pitch angle; When the gravity torque is still greater than the static friction torque of the pitch bearing, the blade pitch angle continues to be reduced according to the preset amplitude; otherwise, the blade pitch angle is stopped from being reduced.

9. A wind turbine generator set pitch control system, characterized in that: The system comprises: A memory and a processor, wherein the memory stores a computer program executed by the processor, and when the computer program is executed by the processor, the processor executes the wind turbine pitch control method according to any one of claims 1 to 8.

10. A wind turbine generator set, characterized in that: The wind turbine generator set includes the wind turbine generator set pitch control system according to claim 9.

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