Wind turbine flutter suppression method and apparatus, and control system and wind turbine

Abstract

The present application relates to the technical field of wind turbines. Provided are a wind turbine flutter suppression method and apparatus, and a control system and a wind turbine. The method comprises: determining a yaw angle between a wind direction and the orientation of a nacelle; and on the basis of the yaw angle, determining a pitch control method for changing a pitch angle. The pitch control method comprises a rotational-speed control based pitch control scheme and a pitch control sequence based pitch control scheme, wherein the rotational-speed control based pitch control scheme comprises: on the basis of the rotational speed of a rotor of a wind turbine, adjusting the pitch angle of blades of the wind turbine, so as to maintain the rotational speed of the rotor within a preset rotational-speed range until wind turbine flutter is suppressed; and the pitch control sequence based pitch control scheme comprises: on the basis of a preset pitch control rule, performing a pitch control operation on the pitch angle of the blades of the wind turbine until the wind turbine flutter is suppressed. By means of the method, the present application can realize wind turbine flutter suppression without using yaw when the wind turbine undergoes a power outage and relies on a low-power backup power source.

Description

Wind turbine flutter suppression method, device, control system and wind turbine Technical Field

[0001] The present application relates to the technical field of wind turbines, and in particular to a method, device, control system, and wind turbine flutter suppression method. Background Art

[0002] For large wind turbines, the likelihood of blade flutter in a stationary state increases with increasing rotor diameter and tower height. Conventional wind turbine flutter suppression typically involves changing the nacelle's wind direction angle (i.e., yaw) in combination with changing the blade pitch angle. Typically, the wind turbine controller drives the yaw motor installed in the nacelle to change the nacelle's orientation, thereby changing the nacelle's wind direction angle. The pitch motor in the hub then changes the blade's installation angle relative to the hub, thereby changing the pitch angle. It's well known that yaw motors consume significant energy, while pitch motors consume less. However, in the event of a grid power outage, wind turbines are sometimes powered by small diesel generators, which often lack sufficient output power to support both yaw and pitch operations. Consequently, wind turbine flutter cannot be effectively suppressed. Summary of the Invention

[0003] In view of this, embodiments of the present application provide a method, device, control system, and wind turbine for suppressing wind turbine flutter, which can suppress wind turbine flutter without using yaw.

[0004] In a first aspect, an embodiment of the present application provides a method for suppressing flutter of a wind turbine, comprising:

[0005] Determine the included angle between the nacelle orientation of the wind turbine and the wind direction;

[0006] Determining a pitch change strategy for changing the pitch angle according to the nacelle wind direction angle; wherein the pitch change strategy includes a speed control pitch change scheme and a pitch sequence pitch change scheme;

[0007] The speed control pitch scheme includes: adjusting the pitch angle of the wind turbine blades according to the speed of the wind turbine rotor, so that the wind turbine rotor speed is maintained within a preset speed range until the flutter of the wind turbine is suppressed;

[0008] The pitch sequence pitch scheme includes: performing pitch operations on the wind turbine blades according to a pitch angle sequence in a preset pitch rule until the flutter of the wind turbine is suppressed.

[0009] In some embodiments, the pitch change strategy for determining the change of the pitch angle according to the nacelle wind direction angle includes:

[0010] When the angle of the cabin wind direction angle is less than the first angle or the angle of the cabin wind direction angle is greater than or equal to the second angle, the speed-controlled pitch change scheme is used to change the pitch angle;

[0011] When the angle of the nacelle wind direction is greater than or equal to the first angle and smaller than the second angle, a pitch sequence pitching scheme is used to change the pitch angle;

[0012] The first angle has a value range of greater than or equal to 40 degrees and less than or equal to 70 degrees; the second angle has a value range of greater than or equal to 110 degrees and less than or equal to 140 degrees.

[0013] In some embodiments, adjusting the pitch angle of the wind turbine blades according to the wind turbine rotor speed so that the wind turbine rotor speed remains within a preset speed range includes:

[0014] wherein, each time the pitch angles of the three blades of the wind turbine are adjusted, a first preset detection time is interval to detect whether the wind rotor speed is within a preset speed range;

[0015] Wherein, the preset speed range refers to between the first speed and the second speed;

[0016] If it is detected that the rotation speed of the wind rotor is less than the first rotation speed, the pitch angles of the three blades of the wind turbine are respectively reduced by a preset adjustment angle;

[0017] If it is detected that the rotation speed of the wind rotor is greater than the second rotation speed, the pitch angles of the three blades of the wind turbine are increased by a preset adjustment angle respectively;

[0018] The relationship between the first speed and the second speed satisfies 0<first speed<second speed<12 rpm.

[0019] In some embodiments, performing pitch operation on the wind turbine blades according to a pitch angle sequence in a preset pitch change rule includes:

[0020] Controlling the three blades of the wind turbine to change the pitch angle to a first sequence value;

[0021] detecting, at intervals of a second preset detection time, whether the flutter of the wind turbine generator is suppressed;

[0022] If it is not suppressed, performing pitch operation on the three blades of the wind turbine according to the preset pitch change rule so that the pitch angle reaches the second sequence value of the pitch angle sequence;

[0023] After the pitch operation, detecting again after the second preset detection time whether the flutter of the wind turbine generator is suppressed;

[0024] If it is not suppressed, continue to perform pitch operation on the three blades of the wind turbine according to the preset pitch change rule, so that the pitch angle reaches the next sequence value in the pitch angle sequence;

[0025] The preset pitch change rules include:

[0026] The pitch angles of the three blades in the pitch angle sequence are successively increased or decreased;

[0027] The difference between the maximum and minimum pitch angles of the same blade in the pitch angle sequence is greater than the maximum value of the pitch angle interval span that generates flutter accumulation;

[0028] An absolute value of a difference between adjacent sequence values ​​of the pitch angle of the same blade in the pitch angle sequence is smaller than a minimum value of a distance between pitch angle intervals generating flutter accumulation.

[0029] In some embodiments, the maximum span of the pitch angle interval generating flutter accumulation is greater than 60 degrees; and the minimum distance between the pitch angle intervals generating flutter accumulation is less than 35 degrees.

[0030] In some embodiments, determining whether the flutter of the wind turbine is suppressed includes:

[0031] Collect vibration signals from tower vibration sensors or blade vibration sensors located on the wind turbine;

[0032] Performing spectrum analysis on the vibration signal, and extracting the amplitude-frequency component of the vibration signal in the 0.2 Hz to 3.0 Hz range as the equivalent amplitude;

[0033] If the equivalent amplitude does not exceed a preset value, it is determined that the flutter of the wind turbine is suppressed, wherein the preset value is in the range of 0.004 m / s^2<preset value<0.1 m / s^2.

[0034] In some embodiments, after the flutter of the wind turbine is suppressed, the method further includes:

[0035] Controlling the three blades of the wind turbine to retract to a feathering position;

[0036] The feathering position refers to a position where the pitch angle is greater than or equal to 80 degrees and less than or equal to 95 degrees.

[0037] In a second aspect, an embodiment of the present application provides a wind turbine flutter suppression device, comprising:

[0038] A calculation module, used to determine a nacelle-wind direction angle between the nacelle orientation of the wind turbine and the wind direction;

[0039] A determination module, configured to determine a pitch change strategy for changing the pitch angle according to the nacelle wind direction angle;

[0040] The pitch control strategy includes a speed control pitch control scheme and a pitch sequence pitch control scheme;

[0041] The speed control pitch scheme includes: adjusting the pitch angle of the wind turbine blades according to the speed of the wind turbine rotor, so that the wind turbine rotor speed is maintained within a preset speed range until the flutter of the wind turbine is suppressed;

[0042] The pitch sequence pitch scheme includes: performing pitch operations on the wind turbine blades according to a pitch angle sequence in a preset pitch rule until the flutter of the wind turbine is suppressed.

[0043] In a third aspect, an embodiment of the present application provides a control system for a wind turbine, comprising a controller and a pitch drive system;

[0044] The pitch drive system is used to receive instructions from the controller and perform pitch control on the blades of the wind turbine;

[0045] The controller is used to execute the above-mentioned wind turbine flutter suppression method and output control instructions to the variable pitch drive system.

[0046] In a fourth aspect, an embodiment of the present application provides a wind turbine, including the above-mentioned control system of the wind turbine.

[0047] The embodiments of the present application have the following beneficial effects: the present application first determines the angle between the wind direction and the cabin wind direction of the cabin; and then determines whether to use a speed-controlled pitch change scheme or a pitch sequence pitch change scheme for pitch change operation according to the cabin wind direction angle. Through this method, the present application can achieve wind turbine flutter suppression without using yaw when the wind turbine loses power and with the help of a lower-power backup power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0049] FIG1 shows a schematic structural diagram of a wind turbine according to an embodiment of the present application;

[0050] FIG2 is a schematic diagram showing the wind direction angle of the cabin according to an embodiment of the present application;

[0051] FIG3 shows a schematic diagram of pitch angles according to an embodiment of the present application;

[0052] FIG4 shows a first flow chart of a method for suppressing flutter of a wind turbine according to an embodiment of the present application;

[0053] FIG5 is a schematic diagram showing a cumulative interval for generating chatter according to an embodiment of the present application;

[0054] FIG6 shows a second flow chart of the method for suppressing flutter of a wind turbine according to an embodiment of the present application;

[0055] FIG7 shows a schematic structural diagram of a wind turbine flutter suppression device according to an embodiment of the present application.

[0056] Component Symbol Description:

[0057] 1-blade; 2-nacelle; 3-tower; 4-hub; 10-calculation module; 20-determination module;

[0058] a-blade azimuth; b-nacelle wind direction angle; c-pitch angle; d-flutter accumulation interval; e-interval span; f-interval distance. DETAILED DESCRIPTION

[0059] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments.

[0060] The components of the embodiments of the present application generally described and illustrated in the drawings herein may be arranged and designed in a variety of different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed application, but rather merely represents selected embodiments of the present application. All other embodiments obtained by those skilled in the art based on the embodiments of the present application without creative effort are within the scope of protection of the present application.

[0061] Hereinafter, the terms "including", "having" and their cognates used in various embodiments of the present application are intended only to indicate specific features, numbers, steps, operations, elements, components or combinations of the aforementioned items, and should not be understood as excluding the existence of one or more other features, numbers, steps, operations, elements, components or combinations of the aforementioned items or adding the possibility of one or more features, numbers, steps, operations, elements, components or combinations of the aforementioned items. In addition, the terms "first", "second", "third" and the like are only used to distinguish descriptions and should not be understood as indicating or implying relative importance.

[0062] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by those skilled in the art to which the various embodiments of the present application belong. The terms (such as those defined in generally used dictionaries) will be interpreted as having the same meaning as in the context of the relevant technical field and will not be interpreted as having an idealized meaning or an overly formal meaning unless clearly defined in the various embodiments of the present application.

[0063] The following describes some embodiments of the present application in detail with reference to the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments may be combined with each other.

[0064] For large wind turbines, as the diameter of the impeller and the height of the tower increase, the possibility of vibration of the wind turbine blades in a static state also gradually increases.

[0065] As shown in Figures 1 to 3, a typical wind turbine includes but is not limited to a tower, a nacelle, a hub and blades, wherein the hub 4 and the blades 1 are combined together to form a wind rotor. The nacelle 2 is mounted on the tower 3, the hub 4 is mounted at the front end of the nacelle 2, and the three blades 1 are symmetrically mounted along the side wall of the hub 4. The angle between the central axis of the nacelle 2 and the wind direction is referred to as the nacelle wind direction angle. The installation angle of the blade 1 relative to the hub 4 is dynamically adjustable. This angle is called the pitch angle, and the pitch angle is shown in Figure 3 c. Under the action of wind, the wind rotor rotates around the central axis of the nacelle 2, and the angle between its blade 1 and the tower 3 is called the blade azimuth angle, and the blade azimuth angle is shown in Figure 1 a.

[0066] In the prior art, wind turbine flutter suppression is typically achieved by changing the nacelle's wind direction angle (i.e., yaw) in combination with the blade pitch angle. Typically, the wind turbine controller drives the yaw motor installed in the nacelle 2 to change the orientation of the nacelle 2, thereby changing the nacelle's wind direction angle. The pitch motor in the hub 4 is then activated to change the blade's installation angle relative to the hub 4, thereby changing the blade pitch angle. It is well known that the yaw motor consumes a lot of energy, while the pitch motor consumes less. However, in the event of a grid power outage, the wind turbine is sometimes powered by a small diesel generator, which has insufficient output power to support both yaw and pitch operations. Consequently, wind turbine flutter cannot be effectively suppressed.

[0067] The present application proposes a method for suppressing wind turbine flutter without relying on yaw and only changing the pitch angle according to pitch control.

[0068] The wind turbine flutter suppression method is described below with reference to some specific embodiments.

[0069] FIG4 shows a flow chart of a method for suppressing wind turbine flutter according to an embodiment of the present application. Exemplarily, the method for suppressing wind turbine flutter includes the following steps:

[0070] Step S100: determining the nacelle-wind direction angle between the orientation of the wind turbine nacelle and the wind direction.

[0071] As shown in Figure 2, the cabin wind direction angle b is specifically the angle between the cabin centerline and the wind direction. When determining the cabin wind direction angle, it can be measured by a wind vane installed on the top of the cabin or a wind tower several kilometers in front of the wind turbine. The wind vane or wind tower can sense the angle between the incident airflow and the centerline of the sensor, and then convert it into an electrical signal and send it to the wind turbine controller to determine the cabin wind direction angle.

[0072] Step S200: determining a pitch change strategy for changing the pitch angle according to the nacelle wind direction angle.

[0073] The pitch change strategy includes a speed control pitch change scheme and a pitch change sequence pitch change scheme.

[0074] The speed-controlled pitch-changing scheme includes: adjusting the pitch angle of the wind turbine blades according to the speed of the wind turbine rotor, so that the wind turbine rotor speed is maintained within a preset speed range until the flutter of the wind turbine is suppressed.

[0075] The pitch sequence pitch scheme includes: performing pitch operations on the wind turbine blades according to a pitch angle sequence in a preset pitch rule until the flutter of the wind turbine is suppressed.

[0076] Generally, for wind turbines, the nacelle wind direction angle and blade pitch angle are important factors affecting wind energy capture. The nacelle wind direction angle ranges from 0 to 180 degrees. When the nacelle wind direction angle approaches 90 degrees, the wind turbine cannot capture wind energy regardless of the angle used. When the nacelle wind direction angle approaches 0 or 180 degrees, appropriate pitch adjustment can capture wind energy and rotate the rotor. The smaller the pitch angle, the greater the wind energy captured and the higher the stable rotor speed. Conversely, the larger the pitch angle, the less wind energy captured. The blade azimuth angle constantly changes during rotor rotation, which does not allow blade flutter to accumulate. Therefore, when the nacelle wind direction angle approaches 0 or 180 degrees, the rotor can be rotated to suppress blade flutter. This can be achieved by using a speed-controlled pitch control scheme. Furthermore, when the wind direction angle of the nacelle is close to 90 degrees, relying on the pitch action is not enough to rotate the wind rotor. At this time, a specific pitch sequence method can be used to suppress flutter, that is, a pitch sequence pitch scheme is used to suppress flutter.

[0077] Furthermore, based on the above-mentioned influence of the nacelle wind direction angle and the pitch angle on capturing wind energy, the pitch change method for determining the change of the pitch angle according to the nacelle wind direction angle described in the present application includes:

[0078] When the angle of the nacelle wind direction angle is less than the first angle or the angle of the nacelle wind direction angle is greater than or equal to the second angle, the speed-controlled pitch change scheme is used to change the pitch angle.

[0079] When the angle of the nacelle wind direction is greater than or equal to the first angle and less than the second angle, a pitch sequence pitching scheme is adopted to change the pitch angle.

[0080] The first angle has a value range of greater than or equal to 40 degrees and less than or equal to 70 degrees; the second angle has a value range of greater than or equal to 110 degrees and less than or equal to 140 degrees.

[0081] Specifically, in the present application, when the nacelle wind direction angle is greater than 0 degrees and less than the first angle, the wind turbine is said to be facing the wind; when the nacelle wind direction angle is greater than or equal to the second angle, the wind turbine is said to be facing away from the wind; and when the nacelle wind direction angle is greater than or equal to the first angle and less than the second angle, the wind turbine is said to be facing sideways to the wind. The selection of the first angle and the second angle must ensure that the wind rotor can effectively rotate when the wind turbine is facing the wind and when the wind turbine is facing away from the wind, and that the wind rotor can hardly rotate when the wind turbine is facing sideways to the wind. In the present application, by using wind turbine load simulation software (such as Bladed) for calculation, the first angle is taken between [40,70] and the second angle is taken between [110,140], which can simultaneously meet the speed requirements of the above three different wind turbine facing wind states.

[0082] It can be understood that in this application, when the wind turbine is facing the wind or facing away from the wind, the speed control pitch scheme is used to change the pitch angle, and when the wind turbine is facing the wind sideways, the pitch sequence pitch scheme is used to change the pitch angle.

[0083] In some embodiments, adjusting the pitch angle of the wind turbine blades according to the wind turbine rotor speed so that the wind turbine rotor speed remains within a preset speed range includes:

[0084] After each adjustment of the pitch angles of the three blades of the wind turbine, a first preset detection time is interval to detect whether the wind wheel speed is within the preset speed range; the preset speed range is between the first speed and the second speed.

[0085] If it is detected that the rotation speed of the wind wheel is less than the first rotation speed, the pitch angles of the three blades of the wind turbine are respectively reduced by a preset adjustment angle.

[0086] If it is detected that the rotation speed of the wind wheel is greater than the second rotation speed, the pitch angles of the three blades of the wind turbine are respectively increased by a preset adjustment angle.

[0087] Since the conditions for flutter accumulation can be destroyed as long as the rotor rotates, the first speed in this application only needs to be greater than 0. To prevent the wind turbine from being unsafe due to excessive rotor speed, the second speed must be set to ensure the safety of the wind turbine. Therefore, the relationship between the first speed and the second speed in this application must satisfy 0 < first speed < second speed < 12 rpm. In addition, the preset adjustment angle needs to be selected based on the control response of the wind turbine. When the first preset detection time is 10 seconds, the preset adjustment angle has a value range of greater than or equal to 1 degree and less than or equal to 8 degrees.

[0088] Specifically, when the wind turbine is facing the wind or facing away from it, the rotor speed is controlled by variable pitch control to maintain it between a first speed and a second speed. The present application can detect the rotor speed directly using circumferential bolts and proximity switches mounted on the main shaft bearing surface of the wind turbine nacelle. Alternatively, a high-speed encoder can be installed on the wind turbine to determine the generator speed, and the rotor speed can be indirectly measured by dividing the generator speed by the gearbox speed ratio. When the speed-controlled variable pitch scheme is first activated, the wind turbine is in a shutdown state. At this time, the rotor speed is zero, which is less than the first speed. The pitch angles of the three blades of the wind turbine are controlled to be reduced by a preset adjustment angle based on the original value. After the first preset detection time, the rotor speed is detected again. If the rotor speed is still less than the first speed, the pitch angles of the three blades of the wind turbine are controlled to be reduced by a preset adjustment angle based on the previous value. If the rotor speed is detected to be greater than the second speed, the pitch angles of the three blades of the wind turbine are controlled to be increased by a preset adjustment angle based on the previous value. As long as the flutter of the wind turbine generator cannot be suppressed, the above steps will be repeated, that is, the rotor speed is detected at intervals of the first preset detection time, and then the pitch angles of the three blades are controlled to increase or decrease by a preset adjustment angle according to the rotor speed. This can prevent the wind rotor from continuously accelerating or decelerating, so that the wind rotor fluctuates within a suitable speed range. Since the azimuth angle of the blades is constantly changing, the conditions for the accumulation of blade flutter are lost, and the blade flutter disappears under the action of its own damping. During the speed control process, when it is detected that the flutter of the wind turbine generator is suppressed, the speed control pitch scheme is stopped, and then the pitch angles of the three blades are controlled to return to the feathering position, even if the pitch angle stays between 80 degrees and 95 degrees. Among them, the first preset detection time is usually between 5 seconds and 30 seconds.

[0089] In some embodiments, performing pitching operations on the wind turbine blades according to a pitch angle sequence in a preset pitching rule includes: controlling the three blades of the wind turbine to pitch to a first sequence value of a pitch angle sequence; detecting whether the flutter of the wind turbine is suppressed after a second preset detection time interval; if not, performing pitching operations on the three blades of the wind turbine according to the preset pitching rule to pitch the pitch angle to a second sequence value of the pitch angle sequence; after the pitching operations, detecting again after the second preset detection time interval whether the flutter of the wind turbine is suppressed; if not, continuing to perform pitching operations on the three blades of the wind turbine according to the preset pitching rule to pitch the pitch angle to the next sequence value of the pitch angle sequence. The above pitching operations and detecting whether the flutter of the wind turbine is suppressed are repeated until the last sequence value in the pitch angle sequence is reached. Then, according to whether the flutter is suppressed, the three blades of the wind turbine are pitched according to the preset pitching rules, so that the pitch angle returns to the feathering position or reaches the first sequence value of the pitch angle sequence, and the above operation is repeated.

[0090] Among them, the preset pitch change rules include: the pitch angles of the three blades in the pitch angle sequence increase or decrease in sequence respectively; the difference between the maximum and minimum values ​​of the pitch angle of the same blade in the pitch angle sequence is greater than the maximum value of the pitch angle interval span that produces flutter accumulation; the absolute value of the difference between adjacent sequence values ​​of the pitch angle of the same blade in the pitch angle sequence is less than the minimum value of the distance between the pitch angle intervals that produce flutter accumulation.

[0091] Specifically, as shown in FIG5 , the span of the pitch angle interval generating flutter accumulation and the distance between adjacent pitch angle intervals generating flutter accumulation are described as follows:

[0092] This application uses computing software with fluid-solid coupling simulation capabilities to conduct simulation studies, examining the blade flutter accumulation of a single blade at different cabin wind direction angles, blade azimuth angles, and pitch angles. The results show that under the influence of any cabin wind direction angle and blade azimuth angle, there is a portion of the pitch angle interval that will produce flutter accumulation, and the other intervals are non-risk intervals (i.e., intervals where no flutter accumulation occurs). In the prior art, some methods will use the method of determining an optimal pitch angle to reduce flutter accumulation, but this method requires knowing the blade azimuth angle, which is relatively complicated. In this application, there is no need to determine the optimal pitch angle, it is only necessary to keep the pitch angle outside the pitch interval that produces flutter accumulation, that is, it is only necessary to keep the pitch angle in the non-risk interval. As shown in Figure 5, within all working ranges of the pitch angle, there may be more than one continuous interval that "generates flutter accumulation". According to analysis, the pitch angle interval span that generates flutter accumulation and the distance between adjacent pitch angle intervals that generate flutter accumulation can be obtained based on all pitch angle intervals that generate flutter accumulation. The interval span e in the gray area in Figure 5 is the pitch angle interval span that generates flutter accumulation, and the distance f between two pitch angle intervals d that generate flutter accumulation is the distance between adjacent pitch angle intervals that generate flutter accumulation. -10 degrees to 100 degrees is the entire working range of the pitch angle.

[0093] Furthermore, when the difference between the maximum and minimum values ​​in the pitch angle sequence exceeds the maximum value of the pitch angle interval that generates flutter accumulation, and the step size of each change in the sequence is less than the minimum distance between intervals that generate flutter accumulation, at least one pitch angle in the pitch angle sequence is guaranteed to be within the non-risk interval, preventing blade flutter accumulation in the wind turbine. It should be noted that since the rotor does not rotate, the risk status of each pitch angle does not change during pitch angle adjustment, making the above solution feasible.

[0094] Specifically, as shown in FIG6 , the specific implementation process of performing the pitch operation on the wind turbine blades according to the pitch angle sequence in the preset pitch change rule is as follows:

[0095] In step S10, the three blades of the wind turbine are controlled to pitch to the initial value of the pitch angle sequence (p11, p12, p13), and then step S20 is executed to detect whether the flutter of the wind turbine is suppressed at an interval of a second preset detection time; if the flutter of the wind turbine is suppressed, step S30 is executed to control the three blades of the wind turbine to return to the feather position; if the flutter of the wind turbine is not suppressed, step S40 is executed to perform pitch operation on the three blades of the wind turbine according to the preset pitch change rule, and the pitch angle after pitch change is (pi1, pi2, pi3); then step S20 and step S40 are executed in a loop until step S30 or step S50 is executed. If step S50 is executed, the pitch angle is changed to (pn1, pn2, pn3), and then step S60 is continued to detect whether the flutter of the wind turbine generator is suppressed at an interval of a second preset detection time. If it is suppressed, step S30 is executed to control the three blades of the wind turbine generator to return to the propeller position. If the flutter of the wind turbine generator is not suppressed, the process returns to step S10.

[0096] The maximum value of the span of the pitch angle interval generating flutter accumulation is defined as px; and the minimum value of the distance between adjacent pitch angle intervals generating flutter accumulation is defined as py.

[0097] According to the specific implementation process shown in Figure 6, the pitch angle sequence {pil.pi2.pi3 (i=1.2…n)} can effectively suppress the flutter of the wind turbine if the following preset pitch control rules are met at the same time:

[0098] Rule 1:

[0099] p11>p21>p31>…>pn1 or p11 <p21<p31<…<pn1

[0100] p12>p22>p32>…>pn2 or p12 <p22<p32<…<pn2

[0101] p13>p23>p33>…>pn3 or p13 <p23<p33<…<pn3

[0102] Rule 2:

[0103] Max{p11,p21,…,pn1}-Min{p11,p21,…,pn1}> px

[0104] Max{p12,p22,…,pn2}-Min{p12,p22,…,pn2}> px

[0105] Max{p13,p23,…,pn3}-Min{p13,p23,…,pn3}> px

[0106] Rule 3:

[0107] Max{abs(p11-p21), abs(p21-p31),… abs(p(n-1)1-pn1)} <py

[0108] Max{abs(p12-p22), abs(p22-p32),… abs(p(n-1)2-pn2)} <py

[0109] Max{abs(p13-p23), abs(p23-p33),… abs(p(n-1)3-pn3)} <py。

[0110] The maximum span px of the pitch angle interval generating flutter accumulation is usually greater than 60 degrees; the minimum distance py between the pitch angle intervals generating flutter accumulation is usually less than 35 degrees.

[0111] Furthermore, the present application provides a method for detecting whether wind turbine flutter is suppressed by collecting vibration signals from a tower vibration sensor or a blade vibration sensor, and determining, based on the vibration signals, whether the amplitude of the signal spectrum between 0.2 Hz and 3.0 Hz exceeds a preset value; if the amplitude does not exceed the preset value, the wind turbine flutter is suppressed; if the amplitude exceeds the preset value, the wind turbine flutter is not suppressed. The preset value is in the range of 0.004 m / s² < preset value < 0.1 m / s².

[0112] The present application is further described below based on a specific implementation method:

[0113] In this specific embodiment, the wind turbine is a long-bladed wind turbine with a vibration sensor installed in its nacelle. A small 20kW diesel generator continuously powers the turbine's components. This power supply enables the turbine's controller, pitch drive system, and communications system to operate effectively.

[0114] In this specific embodiment, the wind vane installed on the top of the cabin can sense the angle between the incident airflow and the central axis of the sensor, and convert it into an electrical signal, which is sent to the controller. The controller can then obtain the cabin wind direction angle based on the electrical signal.

[0115] The wind turbine's nacelle is equipped with a vibration sensor that collects vibration signals from the tower and transmits them to the controller. This vibration signal reflects the real-time vibration acceleration of a single point in the nacelle. This vibration acceleration value is cached for 30 seconds and Fourier transformed every 30 seconds. If, after the Fourier transform, the maximum amplitude of the signal spectrum in the 0.2Hz to 3.0Hz range exceeds 0.1m / s², blade flutter is determined to be present, and the method described in this invention takes effect. Conversely, when the maximum amplitude of the signal spectrum in the 0.2Hz to 3.0Hz range does not exceed 0.01m / s², the wind turbine flutter is determined to be suppressed.

[0116] When wind turbine flutter is detected, the controller reads the nacelle wind direction angle. In this specific embodiment, the first angle is 50 degrees and the second angle is 120 degrees. If the nacelle wind direction angle is less than 50 degrees or greater than 120 degrees, the speed-controlled pitch control scheme is adopted. Conversely, if the nacelle wind direction angle is greater than 50 degrees and less than 120 degrees, the sequential pitch control scheme is adopted.

[0117] In the speed-controlled pitch control scheme, the first speed is 1 rpm, the second speed is 8 rpm, and the preset adjustment angle is 6 degrees. In this specific embodiment, a row of bolts and proximity switches are installed on the main shaft bearing surface of the wind turbine nacelle to directly detect the rotor speed. When the control program is first activated, the wind turbine is shut down and the speed is equal to 0, which is less than the first speed. The controller controls the pitch angle to decrease by a preset adjustment angle (6 degrees), changing the pitch angle from 89 degrees (feathering angle) to 83 degrees. After the first preset detection time (set to 10 seconds in this specific embodiment), the rotor speed is checked again. If the speed is less than 1 rpm, the controller controls the pitch angle to decrease by another 6 degrees. Once the rotor speed exceeds 1 rpm, the pitch angle stabilizes. After this, if the wind speed increases, the speed may increase rapidly. During a certain test, if the speed exceeds 8 rpm (the second speed), the controller controls the pitch angle to increase to avoid excessive speed. Then, after 10 seconds, the wind rotor speed test is performed again. During the speed control, when the vibration signal processing program finds that the wind turbine flutter has been suppressed, the speed control pitch change plan is stopped, and the controller controls the three pitch angles to return to the feathering position (89 degrees in this specific implementation).

[0118] The following implementation method describes the pitch sequence pitch change scheme:

[0119] In the pitch sequence pitch change scheme, simulation studies on a specific aircraft model show that the maximum span of the interval that causes flutter accumulation is 47 degrees, and the minimum interval is 16 degrees. The pitch angle sequence selected in this scheme is as follows:

[0120] { (pi1,pi2,pi3)|(i=1,2,…n)}={(89,89,10),(76,76,23),(62,62,36),(48,48,49),(34,34,72)}.

[0121] As can be seen, when n=5, the three preset rules mentioned in this application method are verified as follows:

[0122] Rule 1:

[0123] p11>p21>p31>p41>p51

[0124] p12>p22>p32>p42>p52

[0125] p13 <p23<p33<p43<p53

[0126] The above pitch angle sequence complies with Rule 1.

[0127] Rule 2:

[0128] Max{p11,p21,p31,p41,p51}-Min{ p11,p21,p31,p41,p51}=55>47

[0129] Max{p12,p22,p32,p42,p52}-Min{ p12,p22,p32,p42,p52}=55>47

[0130] Max{p13,p23,p33,p43,p53}-Min{ p13,p23,p33,p43,p53}=62>47

[0131] It can be seen that the above pitch angle sequence also complies with Rule 2.

[0132] Rule 3:

[0133] max{abs(p11-p21),abs(p21-p31),abs(p31-p41),abs(p41-p51)} =14<16

[0134] max{abs(p12-p22),abs(p22-p32),abs(p32-p42),abs(p42-p52)} =14<16

[0135] max{abs(p13-p23), abs(p23-p33), abs(p33-p43), abs(p43-p53)}=13<16

[0136] It can be seen that the above pitch angle sequence also complies with Rule 3.

[0137] Therefore, the control sequence described above is effective. During specific execution, if wind turbine flutter is detected and the nacelle wind direction angle is between 50 and 120 degrees, the three blades are first pitched to (89, 89, 10), and the system waits for 5 minutes (the second preset detection time in this specific embodiment is 5 minutes). If flutter is still present after 5 minutes, the pitch angles are adjusted to (76, 76, 23), and another 5-minute wait is performed, and so on, until the blades are adjusted to (34, 34, 72). According to design principles, during the above pitch change process, a pitch angle combination must exist. While maintaining this pitch angle, flutter is suppressed. After flutter is suppressed, the three blade pitch angles are controlled to return to the feathered position (89, 89, 89).

[0138] Furthermore, if a sudden change in wind direction occurs during the propeller movement process, the pitch angle range in which flutter accumulates may change. In this relatively unlikely scenario, after moving the propeller to (34, 34, 72) and waiting for more than 5 minutes, the controller detects that blade flutter still exists and adjusts the pitch angle to the first sequence of pitch angle values ​​(89, 89, 10) and repeats the above process until the flutter recovers, then returns to the feathering position (89, 89, 89).

[0139] The present application first determines the angle between the wind direction and the cabin wind direction of the cabin; then determines whether to use a speed-controlled pitch scheme or a pitch sequence pitch scheme for the pitch operation based on the cabin wind direction angle. By this method, the present application can achieve wind turbine flutter suppression without using yaw when the wind turbine loses power. Moreover, by the method of the present application, when the blade azimuth angle is unknown, it is possible to detect whether the flutter is suppressed by relying solely on the vibration signal collected by the tower vibration sensor or the blade vibration sensor. Combined with the speed-controlled pitch scheme of the present application to destroy the flutter accumulation condition or the pitch sequence pitch scheme, a pitch angle that effectively suppresses the flutter is found.

[0140] FIG7 shows a schematic structural diagram of a wind turbine flutter suppression device according to an embodiment of the present application. Exemplarily, the wind turbine flutter suppression device includes:

[0141] The calculation module 10 is used to determine the nacelle-wind direction angle between the nacelle orientation of the wind turbine and the wind direction.

[0142] The determination module 20 is configured to determine a pitch change strategy for changing the pitch angle according to the nacelle wind direction angle.

[0143] The pitch control strategy includes a speed control pitch control scheme and a pitch sequence pitch control scheme;

[0144] The speed control pitch scheme includes: adjusting the pitch angle of the wind turbine blades according to the speed of the wind turbine rotor, so that the wind turbine rotor speed is maintained within a preset speed range until the flutter of the wind turbine is suppressed;

[0145] The pitch sequence pitch scheme includes: performing pitch operations on the wind turbine blades according to a pitch angle sequence in a preset pitch rule until the flutter of the wind turbine is suppressed.

[0146] It can be understood that the device of this embodiment corresponds to the wind turbine flutter suppression method of the above embodiment, and the options in the above embodiment are also applicable to this embodiment, so they will not be described again here.

[0147] The present application also provides a control system for a wind turbine, comprising a controller and a pitch drive system; the pitch drive system is configured to receive instructions from the controller and pitch the blades of the wind turbine; the controller is configured to execute the above-mentioned wind turbine flutter suppression method and output control instructions to the pitch drive system.

[0148] The present application also provides a wind turbine generator, including the above-mentioned wind turbine generator control system.

[0149] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can also be implemented in other ways. The device embodiments described above are merely schematic. For example, the flowcharts and structure diagrams in the accompanying drawings show the possible architectures, functions and operations of the devices, methods and computer program products according to the multiple embodiments of the present application. In this regard, each box in the flowchart or block diagram can represent a module, a program segment or a part of the code, and the module, program segment or a part of the code contains one or more executable instructions for implementing the specified logical functions. It should also be noted that in an alternative implementation, the functions marked in the box can also occur in an order different from that marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the structure diagram and / or flowchart, and the combination of boxes in the structure diagram and / or flowchart, can be implemented using a dedicated hardware-based system that performs the specified function or action, or can be implemented using a combination of dedicated hardware and computer instructions.

[0150] In addition, the functional modules or units in the various embodiments of the present application can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0151] If the functions are implemented in the form of software function modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes a number of instructions for enabling a computer device (which can be a smart phone, personal computer, server, or network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0152] The above is only a specific implementation method of the present application, but the scope of protection of the present application is not limited thereto. Any technician familiar with this technical field can easily think of changes or replacements within the technical scope disclosed in this application, which should be covered by the scope of protection of the present application.

Claims

1. A method for suppressing flutter of a wind turbine, characterized in that: include: Determine the wind direction angle between the nacelle orientation of the wind turbine and the wind direction; Determine a pitch change strategy for changing the pitch angle according to the cabin wind direction angle; wherein the pitch change strategy includes a speed control pitch change scheme and a pitch change sequence pitch change scheme; The speed control pitch change scheme includes: adjusting the pitch angle of the wind turbine blades according to the speed of the wind turbine rotor, so that the wind turbine rotor speed is maintained within a preset speed range until the flutter of the wind turbine is suppressed; The pitch sequence pitch scheme includes: performing pitch operation on the wind turbine blades according to a pitch angle sequence in a preset pitch rule until the flutter of the wind turbine is suppressed.

2. The method for suppressing flutter of a wind turbine according to claim 1, characterized in that: The pitch change strategy for determining the change of the pitch angle according to the nacelle wind direction angle includes: When the angle of the cabin wind direction angle is less than the first angle or the angle of the cabin wind direction angle is greater than or equal to the second angle, the speed control pitch change scheme is used to change the pitch angle; When the angle of the wind direction of the nacelle is greater than or equal to the first angle and less than the second angle, a pitch angle is changed by using a pitch sequence pitch change scheme; The value range of the first angle is greater than or equal to 40 degrees and less than or equal to 70 degrees; the value range of the second angle is greater than or equal to 110 degrees and less than or equal to 140 degrees.

3. The method for suppressing flutter of a wind turbine according to claim 2, characterized in that: The pitch angle of the wind turbine blades is adjusted according to the wind turbine rotor speed, so that the wind turbine rotor speed is maintained within a preset speed range. include: Wherein, after each adjustment of the pitch angles of the three blades of the wind turbine, a first preset detection time is interval to detect whether the rotation speed of the wind rotor is within the preset rotation speed range; Wherein, the preset speed range refers to between the first speed and the second speed; If it is detected that the rotation speed of the wind rotor is less than the first rotation speed, the pitch angles of the three blades of the wind turbine are respectively reduced by preset adjustment angles; If it is detected that the rotation speed of the wind rotor is greater than the second rotation speed, the pitch angles of the three blades of the wind turbine generator are increased by preset adjustment angles respectively; The relationship between the first speed and the second speed satisfies 0<first speed<second speed<12 rpm.

4. The method for suppressing flutter of a wind turbine according to claim 2, characterized in that: The pitching operation of the wind turbine blades according to the pitch angle sequence in the preset pitching rule comprises: Controlling the three blades of the wind turbine to change the pitch angle to a first sequence value of the pitch angle sequence; Detecting whether the flutter of the wind turbine generator is suppressed at an interval of a second preset detection time; If it is not suppressed, the three blades of the wind turbine are subjected to pitch changing operation according to a preset pitch changing rule, so that the pitch angle is changed to a second sequence value of the pitch angle sequence; After the pitch operation, detecting again at an interval of the second preset detection time whether the flutter of the wind turbine generator is suppressed; If it is not suppressed, continue to perform pitch changing operation on the three blades of the wind turbine according to the preset pitch changing rule, so that the pitch angle is changed to the next sequence value of the pitch angle sequence; The preset pitch change rules include: The pitch angles of the three blades in the pitch angle sequence are increased or decreased in sequence respectively; The difference between the maximum and minimum pitch angles of the same blade in the pitch angle sequence is greater than the maximum value of the pitch angle interval span that generates flutter accumulation; The absolute value of the difference between adjacent sequence values ​​of the pitch angle of the same blade in the pitch angle sequence is smaller than the minimum value of the distance between the pitch angle intervals generating flutter accumulation.

5. The method for suppressing flutter of a wind turbine according to claim 4, characterized in that: The maximum value of the span of the pitch angle interval generating flutter accumulation is greater than 60 degrees; the minimum value of the distance between the pitch angle intervals generating flutter accumulation is less than 35 degrees.

6. The method for suppressing flutter of a wind turbine according to claim 1, characterized in that: The determination of whether the flutter of the wind turbine is suppressed includes: Collect vibration signals from a tower vibration sensor or a blade vibration sensor located on the wind turbine; Performing spectrum analysis on the vibration signal, and extracting the amplitude-frequency component of the vibration signal in the range of 0.2 Hz to 3.0 Hz as the equivalent amplitude; If the equivalent amplitude does not exceed the preset value, it is determined that the flutter of the wind turbine is suppressed, wherein the preset value has a value range of 0.004 m / s^2<preset value<0.1 m / s^2.

7. The method for suppressing flutter of a wind turbine according to any one of claims 1 to 6, characterized in that: After the flutter of the wind turbine generator is suppressed, the method further includes: Controlling the three blades of the wind turbine to return to a feathering position; The feathering position refers to a position where the pitch angle is greater than or equal to 80 degrees and less than or equal to 95 degrees.

8. A wind turbine flutter suppression device, characterized in that: include: A calculation module, used to determine a cabin wind direction angle between a cabin orientation of a wind turbine and a wind direction; A determination module, used to determine a variable pitch strategy for changing the pitch angle according to the nacelle wind direction angle; Wherein, the pitch change strategy includes a speed control pitch change scheme and a pitch change sequence pitch change scheme; The speed control pitch change scheme includes: adjusting the pitch angle of the wind turbine blades according to the speed of the wind turbine rotor, so that the wind turbine rotor speed is maintained within a preset speed range until the flutter of the wind turbine is suppressed; The pitch sequence pitch scheme includes: performing pitch operation on the wind turbine blades according to a pitch angle sequence in a preset pitch rule until the flutter of the wind turbine is suppressed.

9. A control system for a wind turbine, characterized in that: Including controller and pitch drive system; The variable pitch drive system is used to receive instructions from the controller and change the pitch of the blades of the wind turbine; The controller is used to execute the wind turbine flutter suppression method according to any one of claims 1 to 7 and output control instructions to the variable pitch drive system.

10. A wind turbine generator, characterized in that: A control system for a wind turbine generator comprising the control system of claim 9.

Images