Method and device for suppressing main bearing load of wind turbine based on independent pitch technology

Abstract

The present invention relates to the technical field of wind turbines, and in particular to a method and device for suppressing the load on a main bearing of a wind turbine set based on an independent pitch control technology. The method and device obtain the gravity of a wind rotor end, the position deviation of a fixed hub coordinate system and a main bearing coordinate system in the x direction, and the elevation angle of the wind turbine set, and then obtain the structural load of the main bearing coordinate system according to the gravity of the wind rotor end, the position deviation of the fixed hub coordinate system and the main bearing coordinate system in the x direction, and the elevation angle of the wind turbine set. Then, the structural load of the main bearing coordinate system is used to obtain the pitch superposition angle of each blade, and then the final pitch angle of each blade is obtained, so that the nodding torque in the main bearing coordinate system can be compensated, the nodding torque of the main bearing can be suppressed, and the load on the main bearing of a large wind turbine set can be reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of wind turbines, and in particular to a method and device for suppressing the load on a main bearing of a wind turbine set based on independent pitch control technology. Background Art

[0002] A wind turbine is a power generation device that converts wind energy into electrical energy. During the operation of a wind turbine, the loads on the main bearing of the wind turbine mainly include: 1. The structural load generated by the design of the wind turbine, which is the component of the gravity moment in the nodding direction generated by the gravity of the blades, hub, pitch system, and main shaft in the wind rotor assembly under the action of the elevation angle; 2. The unbalanced load on the wind rotor surface generated by wind shear, tower shadow, and unbalanced load of blades, which is transmitted to the main bearing through the hub, and is mainly manifested as a nodding moment. For the main bearing, the yaw moment is a non-critical directional load.

[0003] At present, traditional independent pitch control usually considers reducing the unbalanced load in the hub coordinate system. The reference load in its control loop is the nodding moment and yaw moment in the hub coordinate system, which has a good effect on the load in the rotating hub coordinate system. However, for the load in the main bearing coordinate system, the load suppression effect on the main bearing is not optimal because the traditional independent pitch control technology does not fully consider its structural load. Considering the current large-scale design requirements of wind turbines, the main bearings of wind turbines are key components. Therefore, for the subsequent large-scale design of wind turbines, it is crucial to reduce the load in the main bearing coordinate system. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention proposes a method and device for suppressing the main bearing load of a wind turbine generator set based on independent pitch control technology, thereby reducing the main bearing load of a large wind turbine generator set.

[0005] In a first aspect, the present invention provides a method for suppressing the main bearing load of a wind turbine generator system based on independent pitch control technology.

[0006] In the first possible implementation, a method for suppressing the main bearing load of a wind turbine based on independent pitch control technology includes: obtaining the rotor end gravity, the position deviation of the fixed hub coordinate system and the main bearing coordinate system in the x-direction, and the wind turbine elevation angle; obtaining the main bearing coordinate system structural load according to the rotor end gravity, the position deviation, and the wind turbine elevation angle; obtaining the pitch superposition angle of each blade according to the main bearing coordinate system structural load; obtaining the final pitch angle of each blade according to the pitch superposition angle; and performing independent pitch control according to the final pitch angle.

[0007] In combination with the first possible implementation, in the second possible implementation, the structural load of the main bearing coordinate system is obtained according to the wind rotor end gravity, position deviation, and wind turbine elevation angle, including: by calculating Md-offset =F g *L*cos(α) obtains the structural load of the main bearing coordinate system; where M d-offset is the structural load of the main bearing coordinate system, F g is the gravity at the rotor end, L is the position deviation between the fixed hub coordinate system and the main bearing coordinate system in the x direction, and α is the elevation angle of the wind turbine.

[0008] In combination with the first feasible method, in the third feasible method, the variable pitch superposition angle of each blade is obtained according to the structural load of the main bearing coordinate system, including: obtaining the nodding moment and yaw moment in the fixed hub coordinate system; obtaining the main bearing nodding moment compensation value according to the structural load of the main bearing coordinate system; obtaining the nodding direction output angle according to the main bearing nodding moment compensation value and the nodding moment; obtaining the variable pitch superposition angle of each blade according to the nodding direction output angle, the yaw moment, and the azimuth angle of each blade.

[0009] By statically or dynamically compensating the independent pitch nodding moment target load, it is possible to compensate for the nodding load of key components at the rear of the main bearing or hub coordinate system, thereby reducing the key load of the main bearing.

[0010] In combination with the third achievable method, in the fourth achievable method, the main bearing nodding moment compensation value is obtained according to the structural load of the main bearing coordinate system, including: by calculating M d_ref =-M d-offset *γGet the main bearing nodding torque compensation value; where M d_ref is the main bearing nodding torque compensation value, M d-offset is the structural load of the main bearing coordinate system, and γ is the structural load compensation coefficient.

[0011] In combination with the third implementable method, in a fifth implementable method, the output angle of the nodding direction is obtained according to the main bearing nodding torque compensation value and the nodding torque, including:

[0012] By calculation Get the output angle of the nod direction;

[0013] Among them, θ d-offset is the output angle of the nodding direction, θ d_old is the output angle of the nodding direction in the previous state, k p_d To nod the ratio of the control ring, is the integral coefficient of the nodding control loop, M d-f is the DC component of the nodding torque, M d-f-old is the DC component of the nodding torque in the previous state, M d_ref is the main bearing nodding torque compensation value, and Timestep is the discrete time step of the controller.

[0014] In combination with the fifth implementable manner, in a sixth implementable manner, a low-pass filter and a notch filter are combined to separate the DC component of the nodding torque to obtain the DC component of the nodding torque.

[0015] In combination with the second implementable method, in a seventh implementable method, the final pitch angle of each blade is obtained according to the pitch superposition angle, including: obtaining a unified pitch angle; obtaining the final pitch angle of each blade according to the unified pitch angle and the pitch superposition angle of each blade.

[0016] In a second aspect, the present invention provides another wind turbine main bearing load suppression device based on independent pitch technology, comprising a processor and a memory storing program instructions, wherein the processor is configured to execute the wind turbine main bearing load suppression method based on independent pitch technology as described above when running the program instructions.

[0017] In a third aspect, the present invention provides a storage medium storing program instructions, which, when running, execute the above-mentioned method for suppressing the main bearing load of a wind turbine based on the independent pitch control technology.

[0018] It can be seen from the above technical solution that the beneficial technical effects of the present invention are as follows:

[0019] The structural load of the main bearing coordinate system is obtained according to the gravity of the wind rotor end, the position deviation of the fixed hub coordinate system and the main bearing coordinate system in the x-direction, and the elevation angle of the wind turbine. Then, the structural load of the main bearing coordinate system is used to obtain the pitch superposition angle of each blade, and then the final pitch angle of each blade is obtained. This can compensate for the nodding torque in the main bearing coordinate system, suppress the nodding torque of the main bearing, and reduce the load on the main bearing of a large wind turbine. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for the specific embodiments or the prior art description. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn according to the actual scale.

[0021] Figure 1 A schematic diagram of a method for suppressing the main bearing load of a wind turbine generator set based on the independent pitch control technology provided by the present invention;

[0022] Figure 2 A schematic diagram of the structural load in the main bearing coordinate system for calculating the gravity load provided by the present invention;

[0023] Figure 3 A schematic structural diagram of a wind turbine main bearing load suppression device based on independent pitch control technology provided by the present invention;

[0024] Figure 4 A time series comparison diagram of the characteristic load of the main bearing under three simulation strategies provided by the present invention;

[0025] Figure 5 A timing comparison diagram of pitch angle under three strategies during simulation provided by the present invention;

[0026] Figure 6 This is a power timing comparison diagram under three strategies during the simulation provided by the present invention. DETAILED DESCRIPTION

[0027] The following embodiments of the technical solution of the present invention are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and are therefore only used as examples, and cannot be used to limit the protection scope of the present invention.

[0028] It should be noted that, unless otherwise specified, the technical terms or scientific terms used in this application should have the common meanings understood by those skilled in the art to which the invention belongs.

[0029] Combination Figure 1 As shown, this embodiment provides a method for suppressing the main bearing load of a wind turbine based on independent pitch control technology, including:

[0030] Step S01, obtaining the wind rotor end gravity, the position deviation of the fixed hub coordinate system and the main bearing coordinate system in the x direction, and the elevation angle of the wind turbine set;

[0031] Step S02, obtaining the structural load of the main bearing coordinate system according to the wind rotor end gravity, the position deviation of the fixed hub coordinate system and the main bearing coordinate system in the x direction, and the elevation angle of the wind turbine;

[0032] Step S03, obtaining the pitch superposition angle of each blade according to the structural load of the main bearing coordinate system;

[0033] Step S04, obtaining the final pitch angle of each blade according to the pitch superposition angle;

[0034] Step S05: Perform independent pitch change according to the final pitch change angle.

[0035] The structural load of the main bearing coordinate system is obtained through the gravity of the wind rotor end, the position deviation of the fixed hub coordinate system and the main bearing coordinate system in the x-direction, and the elevation angle of the wind turbine. Then, the structural load of the main bearing coordinate system is used to obtain the pitch superposition angle of each blade, and then the final pitch angle of each blade is obtained. This can compensate for the nodding torque in the main bearing coordinate system, suppress the nodding torque of the main bearing, and reduce the load on the main bearing of a large wind turbine.

[0036] Optionally, the main bearing coordinate system structural load is obtained according to the wind rotor end gravity, the position deviation of the fixed hub coordinate system and the main bearing coordinate system in the x direction, and the elevation angle of the wind turbine, including: by calculating M d-offset =F g *L*cos(α) obtains the structural load of the main bearing coordinate system, F g is the gravity at the rotor end, L is the position deviation between the fixed hub coordinate system and the main bearing coordinate system in the x direction, and α is the elevation angle of the wind turbine.

[0037] Optionally, by calculating F g =m*g to obtain the gravity at the wind rotor end; where m is the equivalent mass of the wind rotor end, generally considering the mass of the blades and hub system; g is the acceleration due to gravity.

[0038] In some embodiments, in combination Figure 2 As shown, the wind rotor end gravity F g , the position deviation of the fixed hub coordinate system and the main bearing coordinate system in the x direction, and the elevation angle of the wind turbine are substituted into M d-offset =F g *L*cos(α), obtain the structural load M of the main bearing coordinate system d-offset .

[0039] Optionally, the variable pitch superposition angle of each blade is obtained according to the structural load of the main bearing coordinate system, including: obtaining the nodding moment and yaw moment in the fixed hub coordinate system; obtaining the main bearing nodding moment compensation value according to the structural load of the main bearing coordinate system; obtaining the nodding direction output angle according to the main bearing nodding moment compensation value and the nodding moment; obtaining the variable pitch superposition angle of each blade according to the nodding direction output angle, the yaw moment, and the azimuth angle of each blade.

[0040] This solution expands the traditional independent pitch control technology and uses the nodding torque compensation algorithm of the main bearing coordinate system to change the target value of the traditional independent pitch control, realize the nodding load compensation of the main bearing, and ultimately reduce the critical load of the main bearing.

[0041] Optionally, obtaining the nodding moment and the yaw moment in the fixed hub coordinate system includes: obtaining the blade root load and the azimuth angle, and then using the coordinate system for transformation to obtain the nodding moment and the yaw moment in the fixed hub coordinate system.

[0042] In some embodiments, the rotor azimuth angle φ is measured by a low-speed shaft encoder or a code disc or other angle measuring device. There are at least four ways to obtain the nodding moment and yaw moment in the fixed hub coordinate system. Method 1: Measure the blade root load and use coordinate transformation to obtain the nodding moment M in the fixed hub coordinate system d , yaw moment M qMethod 2: By obtaining the characteristic load Mx and blade root load My in the nodding direction, the characteristic load Mx and blade root load My in the nodding direction are decomposed and then integrated according to the azimuth angle to obtain M in the fixed hub coordinate system. d 、M q Method 3: By obtaining the tower top blade root load My and the characteristic load Mz in the yaw direction, the tower top My and Mz are decomposed and integrated according to the nacelle position to obtain M d 、M q ; Method 4: Obtain the nodding torque M by measuring d , yaw moment M q .

[0043] Optionally, obtaining the main bearing nodding moment compensation value according to the main bearing coordinate system structural load includes: calculating M d_ref =-M d-offset *γGet the main bearing nodding torque compensation value; where M d_ref is the main bearing nodding torque compensation value, M d-offset is the structural load of the main bearing coordinate system, and γ is the structural load compensation coefficient.

[0044] Optionally, obtaining the nodding direction output angle according to the main bearing nodding torque compensation value and the nodding torque includes:

[0045] By calculation Get the output angle of the nod direction;

[0046] Among them, θ d-offset is the output angle of the nodding direction, θ d_old is the output angle of the nodding direction in the previous state, k p_d To nod the ratio of the control ring, is the integral coefficient of the nodding control loop, M d-f is the DC component of the nodding torque, M d-f-old is the DC component of the nodding torque in the previous state, M d_ref is the main bearing nodding torque compensation value, and Timestep is the discrete time step of the controller.

[0047] Optionally, a low-pass filter and a notch filter are combined to separate the DC component of the nodding moment to obtain the DC component of the nodding moment. A low-pass filter and a notch filter are combined to separate the DC component of the yaw moment to obtain the DC component of the yaw moment.

[0048] Optionally, the variable pitch superposition angle of each blade is obtained according to the nod direction output angle, the yaw moment, and the azimuth angle of each blade, including: obtaining the yaw direction output angle according to the yaw moment; obtaining the variable pitch superposition angle of each blade according to the nod direction output angle, the yaw direction output angle, and the azimuth angle of each blade.

[0049] Optionally, by calculating θ newn =θ d-offset *cosφ n +θ q *sinφ n Get the pitch superposition angle of the nth blade; where θ newn is the superposition angle of the pitch of the nth blade, θ d-offset is the output angle of the nodding direction, φ n is the azimuth angle of the nth blade, θ q is the output angle in the yaw direction, and n is a positive integer.

[0050] Optionally, by calculating θ q =θ q_old +k p_q *(M q-f -M q-f_old )+Timestep*k i_q *M q-f Get the yaw direction output angle; where, θ q_old is the yaw output angle of the blade in the previous state, k p_q is the ratio of the yaw control loop, k i_q is the integral coefficient of the yaw control loop, M q-f is the DC component of the yaw moment, M q-f_old is the DC component of the yaw torque in the previous state, and Timestep is the discrete time step of the controller.

[0051] Optionally, obtaining a final pitch angle of each blade according to the pitch superposition angle includes: obtaining a unified pitch angle; and obtaining a final pitch angle of each blade according to the unified pitch angle and the pitch superposition angle of each blade.

[0052] Optionally, by calculating Pitchdem newn =θ+θ newn Get the final pitch angle of the nth blade.

[0053] In some embodiments, the present invention provides another wind turbine main bearing load suppression device based on independent pitch technology, comprising a processor and a memory storing program instructions, and the processor is configured to execute the wind turbine main bearing load suppression method based on independent pitch technology as described above when running the program instructions.

[0054] In some embodiments, the present invention provides a storage medium storing program instructions, which, when running, execute the above-mentioned method for suppressing the main bearing load of a wind turbine based on the independent pitch control technology.

[0055] In some embodiments, a certain 8MW unit is taken as an example to illustrate the effect of this solution. According to the solution of this embodiment, the parameters shown in Table 1 are calculated to obtain the main bearing nodding torque compensation value M. d_ref =1603kNm.

[0056] Table 1 Simulation verification parameters

[0057] model An 8MW unit m 151513kg g <![CDATA[9.8m / s 2 ]]> α 6° L 1.8m γ 10％

[0058] In some embodiments, before the present solution is actually applied, it is first verified using Bladed, a professional simulation software for wind turbine generator sets. Bladed is used to simulate three situations as follows:

[0059] Case A: Disable the independent pitch strategy and use only the traditional unified pitch strategy.

[0060] Case B: Turn on the traditional independent pitch strategy;

[0061] Case C: activating the wind turbine main bearing load suppression strategy based on independent pitch control technology, that is, the solution of this application.

[0062] Under turbulent wind, three cases are simulated respectively, and the following results are obtained: Figure 4 , 5 , the comparison timing diagram shown in 6, Figure 4 During the simulation, the main bearing fatigue load time series under the three strategies are compared. In case C, the main bearing fatigue load is obviously closer to the "0" axis, proving that this scheme indeed reduces the main bearing load. Figure 5 When simulating, the pitch angle timings under the three strategies are compared, and the pitch action amplitude of case C increases to a certain extent. Figure 6 When simulating, the power timing of the three strategies is compared, and the power of the three situations basically does not change. The above proves that the strategy of this scheme can operate stably under the premise of meeting the independent pitch application conditions.

[0063] As a further example, using the DLC1.2 working condition in IEC61400-1, a load simulation of the 4m / s-25m / s power generation working condition is performed, and the fatigue load of the main bearing is counted. The comparison results of the fatigue load M of the main bearing are shown in Table 2:

[0064] Table 2 Statistical results of equivalent fatigue load of main bearing under normal power generation conditions (case A is 100%)

[0065] M Situation A Situation B Case C 4 100％ 94％ 90％ 7 100％ 92％ 87％ 10 100％ 89％ 84％

[0066] As shown in Table 2, when the standard value of the fatigue load M of the main bearing is 4, the strategy of case A is applied, and the fatigue load M of the main bearing is 100% of 4, the strategy of case B is applied, and the fatigue load M of the main bearing is 94% of 4, and the strategy of case C is applied, and the fatigue load M of the main bearing is 90% of 4. According to the statistical results of Table 1, compared with case A, the fatigue load of the main bearing is reduced by at least 10% after the strategy of case C is applied; compared with case B, the fatigue load of the main bearing is reduced by 4%-5% after the strategy of case C is applied. It can be seen that the main bearing load suppression strategy of the wind turbine based on the independent pitch technology of this scheme is applied to a certain 8MW model. Compared with the traditional independent pitch technology, the fatigue load of the main bearing of this scheme is reduced by 4%-5%, and compared with the traditional unified pitch technology, the fatigue load of the main bearing of this scheme is reduced by at least 10%. It can be seen that compared with the existing technology, this scheme has obvious help in reducing the load and weight of the main bearing design of large-capacity units.

Claims

1. A method for suppressing the main bearing load of a wind turbine based on independent pitch technology, characterized in that: include: Obtain the wind rotor end gravity, the position deviation of the fixed hub coordinate system and the main bearing coordinate system in the x-direction, and the elevation angle of the wind turbine; Obtaining the structural load of the main bearing coordinate system according to the wind rotor end gravity, the position deviation, and the wind turbine group elevation angle; Obtaining a pitch superposition angle of each blade according to the structural load of the main bearing coordinate system; Obtaining a final pitch angle of each blade according to the pitch superposition angle; Perform independent pitch change according to the final pitch change angle; The structural load of the main bearing coordinate system is obtained according to the wind rotor end gravity, the position deviation, and the elevation angle of the wind turbine generator set, including: By calculating M d-offset =F g *L*cos(α) obtains the structural load of the main bearing coordinate system; Among them, M d-offset is the structural load of the main bearing coordinate system, F g is the gravity at the wind rotor end, L is the position deviation between the fixed hub coordinate system and the main bearing coordinate system in the x direction, and α is the elevation angle of the wind turbine; Obtaining the pitch superposition angle of each blade according to the structural load of the main bearing coordinate system, including: Obtain the nodding moment and yaw moment in the fixed hub coordinate system; Obtaining a main bearing nodding moment compensation value according to the main bearing coordinate system structural load; Obtaining a nodding direction output angle according to the main bearing nodding torque compensation value and the nodding torque; Obtaining a pitch superposition angle of each blade according to the nodding direction output angle, the yaw moment, and the azimuth angle of each blade; Obtaining the main bearing nodding moment compensation value according to the main bearing coordinate system structural load includes: By calculating M d_ref =-M d-offset *γGet the main bearing nodding torque compensation value; where M d_ref is the main bearing nodding torque compensation value, M d-offset is the structural load of the main bearing coordinate system, γ is the structural load compensation coefficient; Obtaining a nodding direction output angle according to the main bearing nodding torque compensation value and the nodding torque includes: By calculation Get the output angle of the nod direction; Among them, θ d-offset is the output angle of the nodding direction, θ d_old is the output angle of the nodding direction in the previous state, k p_d To nod the ratio of the control ring, is the integral coefficient of the nodding control loop, M d-f is the DC component of the nodding torque, M d-f-old is the DC component of the nodding torque in the previous state, M d_ref is the main bearing nodding torque compensation value, Timestep is the discrete time step of the controller; The DC component of the nodding torque is separated by combining a low-pass filter and a notch filter to obtain the DC component of the nodding torque; Obtaining a final pitch angle of each blade according to the pitch superposition angle includes: Get uniform pitch angle; Obtaining a final pitch angle of each blade according to the unified pitch angle and the pitch superposition angle of each blade; By calculating θ newn =θ d-offset *cosφ n +θ q *sinφ n Get the pitch superposition angle of the nth blade; where θ newn is the superposition angle of the pitch of the nth blade, θ d-offset is the output angle of the nodding direction, φ n is the azimuth angle of the nth blade, θ q is the output angle in the yaw direction, and n is a positive integer; By calculating θ q =θ q_old +k p_q *(M q-f -M q-f_old )+Timestep*k i_q *M q-f Get the yaw direction output angle; where, θ q_old is the yaw output angle of the blade in the previous state, k p_q is the ratio of the yaw control loop, k i_q is the integral coefficient of the yaw control loop, M q-f is the DC component of the yaw moment, M q-f_old is the DC component of the yaw torque in the previous state, and Timestep is the discrete time step of the controller; By calculating Pitchdem newn =θ+θ newn Get the final pitch angle of the nth blade.

2. A wind turbine main bearing load suppression device based on independent pitch control technology, comprising a processor and a memory storing program instructions, characterized in that: The processor is configured to execute the method for suppressing the main bearing load of a wind turbine generator system based on the independent pitch control technology as claimed in claim 1 when running the program instructions.

3. A storage medium storing program instructions, characterized in that: When the program instructions are executed, the method for suppressing the main bearing load of a wind turbine generator set based on the independent pitch control technology as claimed in claim 1 is executed.

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