Method, apparatus, and control system for suppressing flutter in wind turbines, and wind turbines

Abstract

This application relates to the technical field of wind turbines and provides a method, apparatus, control system, and wind turbine for suppressing flutter of a wind turbine, the method comprising the steps of determining a nacelle wind direction angle between the wind direction and the orientation of the nacelle, and determining a pitch control method for changing the pitch angle based on the nacelle wind direction angle, the pitch control method comprising a pitch control scheme by rotational speed control and a pitch control scheme by pitch sequence, the pitch control scheme by rotational speed control comprising maintaining the turbine rotational speed within a predetermined range by adjusting the pitch angle of the wind turbine blades based on the turbine rotational speed of the wind turbine until flutter of the wind turbine is suppressed, and the pitch control scheme by pitch sequence comprising performing a pitch operation on the pitch angle of the wind turbine blades according to a predetermined pitch control rule until flutter of the wind turbine is suppressed. This application provides that by using this method, flutter suppression of a wind turbine can be achieved without using yaw when the wind turbine experiences a power outage and operates on a lower-power backup power source.

Description

Technical Field

[0001] This application relates to the technical field of wind turbines, and particularly to a method, device, control system and wind turbine for suppressing flutter of a wind turbine.

Background Art

[0002] In large wind turbines, with the increase in the diameter of the rotor blades and the height of the tower, the probability of flutter of the blades of the wind turbine in a stationary state is gradually increasing. In the prior art, the suppression of flutter of a wind turbine is usually realized by means of combining the change of the nacelle wind direction angle (i.e., yaw) and the change of the pitch angle. Generally, the control device of the wind turbine changes the direction of the nacelle by driving and operating a yaw motor installed in the nacelle, further changes the nacelle wind direction angle, and changes the attachment angle of the blade to the hub by operating a pitch motor in the hub, thereby changing the pitch angle. As is well known, the energy consumption during the operation of the yaw motor is relatively large, and the power consumption of the pitch motor is relatively small. However, when the power grid is out of power, the wind turbine can only supply power by arranging a small diesel generator, and the output power is insufficient to support the simultaneous operation of yaw and pitch. Therefore, the flutter of the wind turbine cannot be effectively suppressed.

Summary of the Invention

Problems to be Solved by the Invention

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

Means for Solving the Problems

[0004] In a first aspect, the embodiments of this application are a method for suppressing flutter of a wind turbine, comprising: determining a nacelle wind direction angle between the direction of the nacelle of the wind turbine and the wind direction; The steps include determining a pitch control strategy that modifies the pitch angle based on the nacelle wind direction angle, wherein the pitch control strategy includes a pitch control scheme by rotational speed control and a pitch control scheme by pitch sequence control. The pitch control scheme using rotational speed control includes maintaining the turbine rotational speed within a predetermined range by adjusting the pitch angle of the wind turbine blades based on the turbine rotational speed of the wind turbine until the flutter of the wind turbine is suppressed. The pitch control scheme using the pitch sequence provides a method for suppressing flutter in a wind turbine, which includes performing a pitch operation on the blades of the wind turbine based on a pitch angle sequence in a predetermined pitch control rule until the flutter of the wind turbine is suppressed.

[0005] In some embodiments, the step of determining a pitch control strategy that modifies the pitch angle based on the nacelle wind direction angle is: If the angle of the nacelle wind direction is less than the first angle, or if the angle of the nacelle wind direction is greater than or equal to the second angle, the pitch angle is changed by employing the rotational speed control pitch control scheme. If the angle of the nacelle wind direction angle is greater than or equal to the first angle and less than the second angle, the pitch angle is changed by employing a pitch control scheme using a pitch sequence, The range of the first angle is 40 degrees or more and 70 degrees or less, and the range of the second angle is 110 degrees or more and 140 degrees or less.

[0006] In some embodiments, the step of maintaining the turbine rotation speed within a predetermined range by adjusting the pitch angle of the wind turbine blades based on the turbine rotation speed of the wind turbine is performed as follows: Each time the pitch angle of the three blades of the wind turbine is adjusted, a first predetermined detection time interval is set to detect whether the turbine rotation speed is within the predetermined rotation speed range, The aforementioned predetermined rotational speed range refers to the range between the first rotational speed and the second rotational speed, If it is detected that the turbine rotation speed is less than the first rotation speed, the pitch angles of the three blades of the wind turbine are each reduced by a predetermined adjustment angle, If it is detected that the turbine rotation speed exceeds the second rotation speed, the pitch angles of the three blades of the wind turbine generator are each increased by a predetermined adjustment angle, The relationship between the first rotational speed and the second rotational speed satisfies the condition 0 < first rotational speed < second rotational speed < 12 rpm.

[0007] In some embodiments, the step of performing a pitch operation on the blades of the wind turbine based on a pitch angle sequence in a predetermined pitch control rule is: The three blades of the wind turbine are pitch-controlled to the first sequence value of the pitch angle sequence, The second step involves detecting whether the flutter of the wind turbine is suppressed at predetermined detection time intervals, In the case of NO, the pitch angle is moved to the second sequence value of the pitch angle sequence by performing pitch operations on the three blades of the wind turbine according to a predetermined pitch control rule. After the pitch operation, after an interval of the second predetermined detection time, it is detected again whether the flutter of the wind turbine is suppressed. If NO, the pitch operation is continued with respect to the three blades of the wind turbine according to the predetermined pitch control rule, thereby moving the pitch angle to the next sequence value in the pitch angle sequence, The aforementioned predetermined pitch control rule is: The pitch angles of the three blades in the aforementioned pitch angle sequence increase or decrease sequentially, The difference between the maximum and minimum pitch angles of the same blade in the aforementioned pitch angle sequence exceeds the maximum value of the pitch angle interval span that causes flutter accumulation, This includes the condition that 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 distance between pitch angle intervals that cause the accumulation of flutter.

[0008] In some embodiments, the maximum span of the pitch angle intervals that cause flutter accumulation exceeds 60 degrees, and the minimum distance between the pitch angle intervals that cause flutter accumulation is less than 35 degrees.

[0009] In some embodiments, the determination of whether the flutter of the wind turbine is suppressed is made as follows: Collecting vibration signals from tower vibration sensors or blade vibration sensors located on wind turbines, Spectrum analysis is performed on the vibration signal, and the amplitude frequency components in the 0.2Hz to 3.0Hz band of the vibration signal are extracted as equivalent amplitudes. If the equivalent amplitude does not exceed a predetermined value, it is determined that the flutter of the wind turbine has been suppressed, and the range of the predetermined value is set to 0.004 m / s 2 <Predetermined value<0.1m / s 2 This includes doing so.

[0010] In some embodiments, after the flutter of the wind turbine is suppressed, the method is performed. The further step includes controlling the three blades of the wind turbine to return them to the feathering position, The feathering position refers to a position where the pitch angle is between 80 degrees and 95 degrees.

[0011] In a second aspect, the embodiment of the present application is a flutter suppression device for a wind turbine, A calculation module for determining the nacelle wind direction angle between the orientation of the wind turbine nacelle and the wind direction, The system includes a decision module for determining a pitch control strategy that modifies the pitch angle based on the nacelle wind direction angle, The pitch control strategy includes a pitch control scheme based on rotational speed control and a pitch control scheme based on pitch sequence control. The pitch control scheme based on the rotational speed control includes maintaining the turbine rotational speed within a predetermined rotational speed range by adjusting the pitch angle of the blades of the wind turbine until flutter of the wind turbine is suppressed, based on the turbine rotational speed of the wind turbine. The pitch control scheme based on the pitch sequence includes performing a pitch operation on the blades of the wind turbine based on a pitch angle sequence in a predetermined pitch control rule until flutter of the wind turbine is suppressed, and provides a flutter suppression device for the wind turbine.

[0012] In a third aspect, an embodiment of the present application is a control system for a wind turbine, comprising a control device and a pitch drive system. The pitch drive system receives an instruction from the control device and is used to perform pitch control on the blades of the wind turbine. The control device executes the above-described flutter suppression method for the wind turbine and is used to output a control instruction to the pitch drive system, and provides a control system for the wind turbine.

[0013] In a fourth aspect, an embodiment of the present application provides a wind turbine comprising the above-described control system for the wind turbine.

Advantages of the Invention

[0014] Embodiments of the present application have the following beneficial effects. The present application first determines a nacelle wind direction angle between the wind direction and the orientation of the nacelle, and then determines which of the pitch control scheme based on rotational speed control or the pitch control scheme based on a pitch sequence is adopted to perform a pitch operation based on the nacelle wind direction angle. By using such a method, the present application can achieve flutter suppression of the wind turbine without using yaw when the wind turbine loses power and operates with a lower-power backup power source.

Brief Description of the Drawings

[0015] To more clearly explain the technical concept of the embodiments of this application, the drawings necessary for describing the embodiments are briefly described below. It should be understood that the following drawings illustrate some embodiments of this application and should not be considered limiting in scope. Those skilled in the art can obtain further drawings based on these drawings without requiring any creative effort. [Figure 1] Figure 1 is a schematic diagram showing the structure of a wind turbine according to an embodiment of the present invention. [Figure 2] Figure 2 is a schematic diagram showing the nacelle wind direction angle according to an embodiment of the present invention. [Figure 3] Figure 3 is a schematic diagram showing the pitch angle according to an embodiment of the present invention. [Figure 4] Figure 4 is a first flowchart showing a flutter suppression method for a wind turbine according to an embodiment of the present invention. [Figure 5] Figure 5 is a schematic diagram showing the interval that causes flutter accumulation according to an embodiment of the present invention. [Figure 6] Figure 6 is a second flowchart showing a flutter suppression method for a wind turbine according to an embodiment of the present invention. [Figure 7] Figure 7 is a schematic diagram showing the structure of a flutter suppression device for a wind turbine according to an embodiment of the present invention. [Modes for carrying out the invention]

[0016] The technical proposal of the embodiments of this application will be clearly and completely explained below with reference to the drawings of the embodiments of this application. Naturally, the embodiments described are only a part of the embodiments of this application, and not the entirety of the embodiments.

[0017] Typically, the components of the embodiments of the present application shown and illustrated in these drawings can be arranged and designed in a variety of different configurations. Therefore, the following detailed description of the embodiments of the present application shown in the drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the present application. Any other embodiments that a person skilled in the art could obtain based on the embodiments of the present application without requiring inventive work would fall within the scope of the present application.

[0018] In the following description, the terms “includes,” “has,” and their synonyms, which may be used in various embodiments of the present application, are intended solely to indicate specific features, numbers, steps, operations, elements, components, or combinations thereof, and should not be understood as excluding from the outset the existence of one or more other features, numbers, steps, operations, elements, components, or combinations thereof, or as adding the possibility of one or more features, numbers, steps, operations, elements, components, or combinations thereof. Furthermore, terms such as “first,” “second,” “third,” etc., are used solely to distinguish descriptions and should not be understood as indicating or implying relative importance.

[0019] Unless otherwise specified, all terms used herein (including technical and scientific terms) have the same meaning as those generally understood by those skilled in the art to which the various embodiments of this application belong. Such terms (for example, those defined in commonly used dictionaries) shall be interpreted as having the same meaning as their contextual meaning in the relevant art, and shall not be interpreted as having an idealized or overly formal meaning unless explicitly defined in the various embodiments of this application.

[0020] Several embodiments of the present application will be described in detail below with reference to the drawings. The embodiments and features described below can be combined with each other, unless they conflict.

[0021] In large wind turbines, as the diameter of the impeller and the height of the tower increase, the probability of vibration occurring in the turbine blades while the turbine is stationary also gradually increases.

[0022] As shown in Figures 1 to 3, a wind turbine typically comprises a tower, nacelle, hub, and blades, but is not limited to these; a combination of a hub 4 and blades 1 forms the turbine. The nacelle 2 is attached to the tower 3, the hub 4 is attached to the tip of the nacelle 2, and the three blades 1 are attached symmetrically to the side walls of the hub 4. The angle between the central axis of the nacelle 2 and the wind direction is abbreviated as the nacelle wind direction angle, and the mounting angle of the blades 1 relative to the hub 4 is dynamically adjustable; this angle is called the pitch angle, and the pitch angle is shown as c in Figure 3. Due to the action of wind, the turbine rotates around the central axis of the nacelle 2, and the angle between its blades 1 and the tower 3 is called the blade azimuth angle, and the blade azimuth angle is shown as a in Figure 1.

[0023] In conventional technology, flutter suppression of wind turbines is usually achieved by a combination of changing the nacelle wind direction angle (i.e., yaw) and changing the pitch angle. Generally, the control device of a wind turbine changes the orientation of the nacelle 2 by driving a yaw motor installed inside the nacelle 2, thereby changing the nacelle wind direction angle, and changes the mounting angle of the blades relative to the hub 4 by operating a pitch motor inside the hub 4, thereby changing the pitch angle. As is well known, the energy consumption of the yaw motor is relatively large when it is in operation, while the power consumption of the pitch motor is relatively small. However, in the event of a power outage in the power grid, wind turbines can only be supplied with power by deploying a small diesel generator, and the output power is insufficient to support the simultaneous operation of yaw and pitch. For this reason, flutter of the wind turbine cannot be effectively suppressed.

[0024] This invention proposes a method for suppressing flutter in wind turbines by changing the pitch angle solely through pitch control, without relying on yaw.

[0025] The following describes a method for suppressing flutter in a wind turbine, with reference to several specific examples.

[0026] Figure 4 shows a flowchart of a flutter suppression method for a wind turbine according to an embodiment of the present invention. Exemplarily, the flutter suppression method for the wind turbine includes the following steps S100 and S200.

[0027] Step S100 determines the nacelle wind direction angle, which is the relationship between the orientation of the wind turbine nacelle and the wind direction.

[0028] As shown in Figure 2, the nacelle wind direction angle b is specifically the angle between the central axis of the nacelle and the wind direction. The nacelle wind direction angle can be determined by measuring it using a wind vane mounted on the top of the nacelle or an anemometer located several kilometers in front of the wind turbine. The wind vane or anemometer senses the angle between the incoming airflow and the central axis of the sensor, converts this into an electrical signal, and transmits it to the control device of the wind turbine, which can then determine the nacelle wind direction angle.

[0029] In step S200, a pitch control strategy is determined that modifies the pitch angle based on the nacelle wind direction angle.

[0030] The pitch control strategy includes a pitch control scheme based on rotational speed control and a pitch control scheme based on pitch sequences.

[0031] The pitch control scheme using rotational speed control includes maintaining the turbine rotational speed within a predetermined range by adjusting the pitch angle of the wind turbine blades based on the turbine rotational speed of the wind turbine until the flutter of the wind turbine is suppressed.

[0032] The pitch control scheme using the pitch sequence includes performing a pitch operation on the blades of the wind turbine based on a pitch angle sequence in a predetermined pitch control rule until the flutter of the wind turbine is suppressed.

[0033] Generally, in wind turbines, the nacelle wind direction angle and pitch angle are important factors that affect wind energy capture. The angular range of the nacelle wind direction angle is [0, 180]. When the nacelle wind direction angle is close to 90 degrees, no wind turbine can capture wind energy regardless of the angle used. When the nacelle wind direction angle is close to 0 or 180 degrees, wind energy can be captured by appropriately adjusting the pitch angle. When the turbine is rotated, a smaller pitch angle results in more wind energy capture and a higher stable rotational speed for the turbine. Conversely, a larger pitch angle results in less wind energy capture. When the turbine rotates, the blade azimuth angle is constantly changing, so the conditions for blade flutter accumulation are not present. Therefore, when the nacelle wind direction angle is close to 0 or 180 degrees, blade flutter can be suppressed by rotating the turbine; that is, flutter can be suppressed by employing a pitch control scheme based on rotational speed control. Furthermore, when the nacelle wind direction angle is close to 90 degrees, pitch motion alone is insufficient to rotate the turbine. In this case, a specific pitch sequence scheme can be employed to suppress flutter; that is, a pitch control scheme using a pitch sequence is employed to suppress flutter.

[0034] Furthermore, based on the influence of the above-mentioned nacelle wind direction angle and pitch angle on wind energy capture, the step of determining a pitch control method for changing the pitch angle based on the nacelle wind direction angle as described in this application is: If the angle of the nacelle wind direction is less than the first angle, or if the angle of the nacelle wind direction is greater than or equal to the second angle, the pitch angle is changed by employing the rotational speed control pitch control scheme. This includes, if the angle of the nacelle wind direction is greater than or equal to a first angle and less than a second angle, changing the pitch angle by employing a pitch control scheme using a pitch sequence.

[0035] The range of the first angle is 40 degrees or more and 70 degrees or less, and the range of the second angle is 110 degrees or more and 140 degrees or less.

[0036] Specifically, in this application, when the nacelle wind direction angle is greater than 0 degrees and less than the first angle, it is called the wind turbine's headwind state; when the nacelle wind direction angle is greater than or equal to the second angle, it is called the wind turbine's tailwind state; and when the nacelle wind direction angle is greater than or equal to the first angle and less than the second angle, it is called the wind turbine's crosswind state. In selecting the first and second angles, it is necessary to ensure that the turbine can rotate effectively when the wind turbine is in a headwind state and when it is in a tailwind state, and that the turbine can hardly rotate when the wind turbine is in a crosswind state. In this application, calculations are performed using wind turbine load simulation software (e.g., Bladed), and by setting the value of the first angle to [40,70] and the value of the second angle to [110,140], the rotational speed requirements for the three different wind direction states of the wind turbine can be simultaneously satisfied.

[0037] To make it clear, in this application, when the wind turbine is in a wind-facing state or a tailwind state, a pitch control scheme using rotational speed control is employed to change the pitch angle, and when the wind turbine is in a crosswind state, a pitch control scheme using a pitch sequence is employed to change the pitch angle.

[0038] In some embodiments, the step of maintaining the turbine rotation speed within a predetermined range by adjusting the pitch angle of the wind turbine blades based on the turbine rotation speed of the wind turbine is performed as follows: Each time the pitch angle of the three blades of the wind turbine is adjusted, a first predetermined detection time interval is set to detect whether the turbine rotation speed is within the predetermined rotation speed range, wherein the predetermined rotation speed range refers to the range between the first rotation speed and the second rotation speed. If it is detected that the turbine rotation speed is less than the first rotation speed, the pitch angles of the three blades of the wind turbine are each reduced by a predetermined adjustment angle, The method includes, when it is detected that the turbine rotation speed exceeds the second rotation speed, increasing the pitch angle of each of the three blades of the wind turbine generator by a predetermined adjustment angle.

[0039] Since the rotation of the turbine can break the conditions for flutter accumulation, in this application, the first rotational speed only needs to be greater than 0. In order to avoid compromising the safety of the wind turbine if the turbine rotational speed is too fast, the setting of the second rotational speed needs to ensure the safety of the wind turbine, and therefore, in this application, the relationship between the first rotational speed and the second rotational speed must satisfy 0 < first rotational speed < second rotational speed < 12 rpm. Furthermore, the predetermined adjustment angle needs to be selected according to the control response status of the wind turbine, and when the value of the first predetermined detection time is set to 10 seconds, the value range of the predetermined adjustment angle is between 1 degree and 8 degrees.

[0040] Specifically, when the wind turbine is facing or behind the wind, the turbine rotation speed is maintained between the first and second rotation speeds by pitch control. In this application, when detecting the turbine rotation speed, the turbine rotation speed may be directly detected using circumferential bolts and proximity switches attached to the main shaft bearing surface of the wind turbine nacelle, or the rotation speed of the generator may be determined by attaching a high-speed encoder to the wind turbine, and the turbine rotation speed may be measured indirectly by dividing the generator rotation speed by the gearbox speed ratio. When the pitch control scheme by rotation speed control is first started, the wind turbine is in a stopped state, and at this time the turbine rotation speed is 0, which is less than the first rotation speed, so the pitch angles of the three blades of the wind turbine are controlled to decrease by a predetermined adjustment angle from the original pitch angle. After a first predetermined detection time interval, the turbine rotation speed is detected again, and if it is detected that the turbine rotation speed is still less than the first rotation speed, the pitch angles of the three blades of the wind turbine are controlled to decrease by a predetermined adjustment angle from the pitch angle after the previous adjustment. If it is detected that the turbine rotational speed exceeds the second rotational speed, the pitch angles of the three blades of the wind turbine are controlled to increase by a predetermined adjustment angle from the pitch angle after the previous adjustment. The above steps are repeated until the flutter of the wind turbine is suppressed, that is, at each interval of the first predetermined detection time, the turbine rotational speed is detected, and then the pitch angles of the three blades are controlled to increase or decrease by one predetermined adjustment angle based on the turbine rotational speed. This allows the turbine to vary within an appropriate rotational speed range by avoiding continuous acceleration or deceleration of the turbine. Because the blade azimuth angle is constantly changing, the conditions for accumulation of blade flutter are lost, and blade flutter is eliminated due to its own damping effect. If it is detected during the rotational speed control process that the flutter of the wind turbine has been suppressed, the execution of the pitch control scheme by rotational speed control is stopped, and then the pitch angles of the three blades are controlled to return to the feathering position, that is, to maintain the pitch angles between 80 and 95 degrees. The first predetermined detection time is usually between 5 and 30 seconds.

[0041] In some embodiments, the step of performing a pitch operation on the blades of the wind turbine based on a pitch angle sequence in a predetermined pitch control rule includes: pitching the three blades of the wind turbine to a first sequence value in the pitch angle sequence; detecting, after a second predetermined detection time interval, whether the flutter of the wind turbine is suppressed; if NO, pitching the three blades of the wind turbine to a second sequence value in the pitch angle sequence by performing a pitch operation on them according to a predetermined pitch control rule; detecting again, after the pitch operation, whether the flutter of the wind turbine is suppressed after a second predetermined detection time interval; if NO, continuing to pitch the three blades of the wind turbine according to the predetermined pitch control rule to pitch the pitch angle to the next sequence value in the pitch angle sequence. The pitch operation and the operation of detecting whether the flutter of the wind turbine is suppressed are repeated until the last sequence value in the pitch angle sequence is reached. Next, depending on whether flutter is suppressed, the pitch is controlled for the three blades of the wind turbine according to a predetermined pitch control rule to return the pitch angle to the feathering position or to the first sequence value of the pitch angle sequence, and the above operation is repeated.

[0042] The predetermined pitch control rule includes the following: the pitch angles of the three blades in the pitch angle sequence are sequentially increased or sequentially decreased; the difference between the maximum and minimum pitch angles of the same blade in the pitch angle sequence exceeds the maximum span of the pitch angle interval that causes flutter accumulation; and the absolute value of the difference between adjacent sequence values ​​of the pitch angles of the same blade in the pitch angle sequence is less than the minimum distance between the pitch angle intervals that cause flutter accumulation.

[0043] Specifically, as shown in Figure 5, the span of the pitch angle interval that causes flutter accumulation, and the distance between adjacent pitch angle intervals that cause flutter accumulation will be explained below. In this application, simulation studies were conducted using computational software with fluid-structure interaction simulation capabilities to examine the accumulation of blade flutter when a single blade is at different nacelle wind direction angles, blade azimuth angles, and pitch angles. The results showed that, under the action of arbitrary nacelle wind direction angles and blade azimuth angles, flutter accumulates in some pitch angle ranges, while other ranges are non-risk ranges (i.e., ranges that do not cause flutter accumulation). In the prior art, flutter accumulation can be reduced by determining the optimal pitch angle, but this method is more complex because it requires knowing the blade azimuth angle. In this application, it is not necessary to determine the optimal pitch angle; it is only necessary to maintain the pitch angle outside the pitch range that causes flutter accumulation, that is, to maintain the pitch angle in a non-risk range. As shown in Figure 5, within the entire operating range of the pitch angle, there may be multiple consecutive sections that "cause flutter accumulation." Analysis reveals that, based on all pitch angle sections that cause flutter accumulation, the span of the pitch angle section that causes flutter accumulation and the distance between adjacent such flutter-causing pitch angle sections can be obtained. In Figure 5, the span e in the gray area represents the span of the pitch angle section that causes flutter accumulation, and the distance f between two pitch angle sections d that cause flutter accumulation represents the distance between adjacent such flutter-causing pitch angle sections. The range from -10 degrees to 100 degrees represents the entire operating range of the pitch angle.

[0044] Furthermore, if the difference between the maximum and minimum values ​​in the pitch angle sequence exceeds the maximum value of the pitch angle interval that causes flutter accumulation, and the change step size per sequence is less than the minimum distance between the intervals that cause flutter accumulation, then the pitch angle sequence will always contain at least one pitch angle within a non-risk interval, thereby preventing blade flutter accumulation in the wind turbine. It should be explained that since the turbine is not rotating, the risk status of each pitch angle does not change during the pitch angle adjustment process, and therefore the above scheme is feasible.

[0045] Specifically, as shown in Figure 6, the step of performing a pitch operation on the blades of the wind turbine based on a pitch angle sequence in a predetermined pitch control rule is as follows: In step S10, the three blades of the wind turbine are pitch-controlled to the initial values ​​(p11, p12, p13) of the pitch angle sequence. Next, step S20 is executed to detect whether the flutter of the wind turbine is suppressed after a second predetermined detection time interval. 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 feathering position. If the flutter of the wind turbine is not suppressed, step S40 is executed to perform a pitch operation on the three blades of the wind turbine according to a predetermined pitch control rule, setting the pitch angle after pitch control to (pi1, pi2, pi3). Steps S20 and S40 are then repeatedly executed until step S30 or step S50 is executed. If step S50 is executed, the pitch is controlled to the pitch angle (pn1, pn2, pn3). Next, step S60 is executed to detect whether the flutter of the wind turbine is suppressed after a second predetermined detection time interval. If YES, step S30 is executed to control the three blades of the wind turbine to return to the feathering position. If the flutter of the wind turbine is not suppressed, the process returns to step S10.

[0046] The maximum span of a pitch angle interval that causes flutter accumulation is defined as px, and the minimum distance between adjacent pitch angle intervals that cause flutter accumulation is defined as py.

[0047] According to the pitch angle sequence {pil,pi2,pi3(i=1,2,…,n)} in the specific implementation process shown in Figure 6, if the following predetermined pitch control rules can be simultaneously satisfied, flutter of the wind turbine can be effectively suppressed. Rule 1: p11>p21>p31>...>pn1 or p11 <p21<p31<…<pn1 p12>p22>p32>...>pn2 or p12 <p22<p32<…<pn2 p13>p23>p33>...>pn3 or p13 <p23<p33<…<pn3

[0048] Rule 2: Max{p11,p21,…,pn1}-Min{p11,p21,…,pn1}>px Max{p12,p22,…,pn2}-Min{p12,p22,…,pn2}>px Max{p13,p23,…,pn3}-Min{p13,p23,…,pn3}>px

[0049] Rule 3: Max{abs(p11-p21),abs(p21-p31),…abs(p(n-1)1-pn1)} <py Max{abs(p12-p22),abs(p22-p32),…abs(p(n-1)2-pn2)} <py Max{abs(p13-p23),abs(p23-p33),…abs(p(n-1)3-pn3)} <py。

[0050] The maximum span px of the pitch angle intervals that cause the aforementioned flutter accumulation is usually greater than 60 degrees, and the minimum distance py between the pitch angle intervals that cause the aforementioned flutter accumulation is usually less than 35 degrees.

[0051] Furthermore, in this application, the method for detecting whether the flutter of a wind turbine is suppressed is as follows: A vibration signal is collected from a tower vibration sensor or a blade vibration sensor, and based on the vibration signal, it is determined whether the amplitude of the signal spectrum in the range of 0.2 Hz to 3.0 Hz exceeds a predetermined value. If the amplitude does not exceed the predetermined value, the flutter of the wind turbine is suppressed; if the amplitude exceeds the predetermined value, the flutter of the wind turbine is not suppressed. The range of the predetermined value is 0.004 m / s. 2 <Predetermined value<0.1m / s 2 That is the case.

[0052] The solution of this application will be further described below based on specific embodiments. In this specific embodiment, the wind turbine is a single wind turbine with long blades, a vibration sensor is mounted on the nacelle of the wind turbine, and simultaneously, a small diesel generator (20kW) is continuously operating to supply power to the wind turbine's equipment. The power supply enables the wind turbine's control system, pitch drive system, and communication system to operate effectively.

[0053] In this specific embodiment, a wind vane mounted on the top of the nacelle can sense the angle between the incoming airflow and the central axis of the sensor, convert this into an electrical signal, and transmit it to a control device, which can then obtain the nacelle wind direction angle based on the electrical signal.

[0054] A vibration sensor is attached to the nacelle of the wind turbine. The vibration sensor collects vibration signals from the tower and transmits them to the control unit. The vibration signal reflects the real-time vibration acceleration at a single point on the nacelle. This vibration acceleration value is temporarily stored for 30 seconds, and a Fourier transform is performed once every 30 seconds. After the Fourier transform, the maximum amplitude of the signal spectrum in the 0.2Hz to 3.0Hz band is 0.1m / s². 2If it is detected that the value exceeds this, it is determined that blade flutter occurs, and the method of the present invention begins to function. Conversely, if the maximum amplitude of the signal spectrum in the range of 0.2 Hz to 3.0 Hz is 0.01 m / s 2 If the value does not exceed a certain threshold, it is determined that the flutter of the wind turbine has been suppressed.

[0055] If flutter is detected in the wind turbine, the control device reads the nacelle wind direction angle. In this specific embodiment, if the first angle is 50 and the second angle is 120, and the control device detects that the nacelle wind direction angle is less than 50 degrees or greater than 120 degrees, it employs a pitch control scheme based on rotational speed control. Conversely, if the control device detects that the nacelle wind direction angle is greater than 50 degrees but less than 120 degrees, it employs a pitch control scheme based on pitch sequence control.

[0056] In the pitch control scheme using rotational speed control, the first rotational speed is set to 1 rpm, the second rotational speed to 8 rpm, and the predetermined adjustment angle to 6 degrees. In this specific embodiment, the turbine rotational speed can be directly detected by attaching a row of bolts and proximity switches to the main shaft bearing surface of the wind turbine nacelle. When the control program is first started, the wind turbine is stopped, the rotational speed is equal to 0, and is less than the first rotational speed. Therefore, the control device controls the pitch angle to decrease by the predetermined adjustment angle (6 degrees), changing the pitch angle from the feathering angle of 89 degrees to 83 degrees. Next, after a first predetermined detection time (in this specific embodiment, the first predetermined detection time is set to 10 seconds), the turbine rotational speed is detected again, and if the rotational speed is less than 1 rpm, the control device controls the pitch angle to decrease by a further 6 degrees. After the turbine rotational speed exceeds 1 rpm, the pitch angle stabilizes. Subsequently, if the wind speed increases, it may cause a rapid increase in rotational speed. In a certain detection, if the rotational speed exceeds 8 rpm (second rotational speed), the control device avoids an excessive increase in rotational speed by controlling the pitch angle. Then, after 10 seconds, the turbine rotational speed is detected again, and if the vibration signal processing program detects that the flutter of the wind turbine has been suppressed in the rotational speed control, the control device stops executing the pitch control scheme based on rotational speed control and controls the three pitch angles to return to the feathering position (89 degrees in this specific embodiment).

[0057] In the following embodiment, a pitch control scheme using a pitch sequence will be described. Simulation studies of a particular type of pitch control scheme using pitch sequences have shown that the maximum span of a section that causes flutter accumulation is 47 degrees, and the minimum interval between sections is 16 degrees. The pitch angle sequence selected in this solution is as follows: {(pi1,pi2,pi3)|(i=1,2,…n)}={(89,89,10),(76,76,23),(62,62,36),(48,48,49),(34,34,72)}

[0058] As can be seen from the above, n=5, and the three prescribed rules mentioned in the method of this application are verified as follows. Rule 1: p11>p21>p31>p41>p51 p12>p22>p32>p42>p52 p13 <p23<p33<p43<p53 The above pitch angle sequence conforms to Rule 1.

[0059] Rule 2: Max{p11,p21,p31,p41,p51}-Min{p11,p21,p31,p41,p51}=55>47 Max{p12,p22,p32,p42,p52}-Min{p12,p22,p32,p42,p52}=55>47 Max{p13,p23,p33,p43,p53}-Min{p13,p23,p33,p43,p53}=62>47 As can be seen from the above, the above pitch angle sequence also conforms to Rule 2.

[0060] Rule 3: max{abs(p11-p21),abs(p21-p31),abs(p31-p41),abs(p41-p51)}=14<16 max{abs(p12-p22),abs(p22-p32),abs(p32-p42),abs(p42-p52)}=14<16 max{abs(p13-p23),abs(p23-p33),abs(p33-p43),abs(p43-p53)}=13<16 As can be seen from the above, the above pitch angle sequence also conforms to Rule 3.

[0061] Therefore, the control sequence described above is effective, and when it is specifically implemented, if flutter is detected in the wind turbine and the nacelle wind direction angle is between 50 and 120 degrees, first the pitch angles of the three blades are adjusted to (89, 89, 10), and a 5-minute wait is performed (in this specific embodiment, the second predetermined detection time is 5 minutes). If flutter is still detected after 5 minutes, the pitch angles are then adjusted to (76, 76, 23), another 5-minute wait is performed, and the same procedure is continued until the pitch angles are adjusted to (34, 34, 72). According to the design principle, in the pitch control process described above, a combination of pitch angles always exists, and during the waiting process to maintain that pitch angle, flutter is suppressed, and after the flutter is suppressed, the three pitch angles are controlled to return to the feathering position (89, 89, 89).

[0062] Furthermore, if the wind direction changes abruptly during the pitch adjustment process, the pitch angle interval that causes the aforementioned flutter accumulation may change. If the probability of this happening is relatively low, the control device adjusts the pitch to (34,34,72) and waits for 5 minutes or more. If the control device then discovers that blade flutter is still occurring, it adjusts the pitch angle to the first sequence value of the pitch angle (89,89,10) and repeats the above process. After the flutter has disappeared, the feathering position is returned to (89,89,89).

[0063] This invention first determines the nacelle wind direction angle between the wind direction and the nacelle orientation, and then, based on the nacelle wind direction angle, determines whether to employ a pitch control scheme based on rotational speed control or a pitch control scheme based on a pitch sequence to perform pitch operation. By using this method, this invention can suppress flutter of a wind turbine without using yaw when the wind turbine experiences a power outage. Furthermore, by using the method of this invention, it is possible to detect whether flutter is suppressed using only vibration signals collected by a tower vibration sensor or a blade vibration sensor, even without knowing the blade azimuth angle. The pitch control scheme based on rotational speed control of this invention is used to break the conditions for flutter accumulation, or the pitch control scheme based on a pitch sequence is used to find a pitch angle that effectively suppresses flutter.

[0064] Figure 7 shows a schematic diagram of the structure of a flutter suppression device for a wind turbine according to an embodiment of the present invention. Exemplarily, the flutter suppression device for the wind turbine is: A calculation module 10 for determining the nacelle wind direction angle between the orientation of the wind turbine nacelle and the wind direction, The system includes a decision module 20 for determining a pitch control strategy that modifies the pitch angle based on the nacelle wind direction angle.

[0065] The pitch control strategy includes a pitch control scheme based on rotational speed control and a pitch control scheme based on pitch sequence control. The pitch control scheme using rotational speed control includes maintaining the turbine rotational speed within a predetermined range by adjusting the pitch angle of the wind turbine blades based on the turbine rotational speed of the wind turbine until the flutter of the wind turbine is suppressed. The pitch control scheme using the pitch sequence includes performing a pitch operation on the blades of the wind turbine based on a pitch angle sequence in a predetermined pitch control rule until the flutter of the wind turbine is suppressed.

[0066] As can be understood, the apparatus of this embodiment corresponds to the flutter suppression method for the wind turbine of the above embodiment, and the optional embodiments of the above embodiment are similarly applicable to this embodiment, so they will not be described again here.

[0067] The present invention further provides a control system for a wind turbine, comprising a control device and a pitch drive system, wherein the pitch drive system is used to receive commands from the control device and to perform pitch control on the blades of the wind turbine, and the control device is used to execute a flutter suppression method for the wind turbine and to output control commands to the pitch drive system.

[0068] This application further provides a wind turbine equipped with the above-described control system for wind turbines.

[0069] In some embodiments provided herein, it should be understood that the disclosed apparatus and methods can be implemented in other ways. The apparatus embodiments described above are merely illustrative, and for example, the flowcharts and block diagrams in the drawings illustrate the architecture, function, and operation of possible implementations of the apparatus, methods, and computer program products relating to some embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, program segment, or part of code containing one or more executable instructions for implementing a defined logical function. It should also be noted that in alternative implementations, the functions represented in the blocks may occur in a different order than that shown in the drawings. For example, two blocks shown successively may actually be executed essentially simultaneously, or they may be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram and / or flowchart, and combinations of blocks in a block diagram and / or flowchart, may be implemented by a dedicated hardware-based system that performs the defined function or operation, or by a combination of dedicated hardware and computer instructions.

[0070] Furthermore, in each embodiment of the present application, each functional module or unit may be integrated with one another to form an independent part, each module may exist independently, and two or more modules may be integrated to form an independent part.

[0071] The aforementioned functions may be implemented in the form of software function modules and, when sold or used as independent products, may be stored on a computer-readable storage medium. Based on this understanding, the essential or prior art contributions of the present invention, or any part thereof, may be embodied in the form of a software product, which is stored on a storage medium containing some instructions for causing a single computer device (which may be a smartphone, personal computer, server, or network device, etc.) to perform all or part of the steps of the methods described in each embodiment of the present invention. The storage medium includes various media capable of storing program code, such as USB memory, portable hard disks, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0072] The above description is merely a specific embodiment of the present application, and the scope of protection of the present application is not limited thereto. Any modification or substitution that a person skilled in the art could easily conceive within the technical scope disclosed herein should be included within the scope of protection of the present application. [Explanation of symbols]

[0073] 1 Blade 2 Nacer 3 Towers 4 hubs 10 Computing Modules 20 Decision Modules a. Blade azimuth b. Nacelle wind direction c pitch angle d Intervals that cause flutter accumulation e interval span f interval distance

Claims

1. A method for suppressing flutter in a wind turbine, The steps include determining the nacelle wind direction angle between the orientation of the wind turbine nacelle and the wind direction, The steps include determining a pitch control strategy that modifies the pitch angle based on the nacelle wind direction angle, wherein the pitch control strategy includes a pitch control scheme by rotational speed control and a pitch control scheme by pitch sequence control. The pitch control scheme using rotational speed control includes maintaining the turbine rotational speed within a predetermined range by adjusting the pitch angle of the wind turbine blades based on the turbine rotational speed of the wind turbine until the flutter of the wind turbine is suppressed. A method for suppressing flutter in a wind turbine, characterized in that the pitch control scheme using the pitch sequence includes performing a pitch operation on the blades of the wind turbine based on a pitch angle sequence in a predetermined pitch control rule until the flutter of the wind turbine is suppressed.

2. The step of determining a pitch control strategy that modifies the pitch angle based on the nacelle wind direction angle is: If the nacelle wind direction angle is less than the first angle, or if the nacelle wind direction angle is greater than or equal to the second angle, the pitch angle is changed by employing the rotational speed control pitch control scheme. If the angle of the nacelle wind direction angle is greater than or equal to the first angle and less than the second angle, the pitch angle is changed by employing a pitch control scheme using a pitch sequence, The flutter suppression method for a wind turbine according to claim 1, characterized in that the range of the first angle is 40 degrees or more and 70 degrees or less, and the range of the second angle is 110 degrees or more and 140 degrees or less.

3. The step of adjusting the pitch angle of the blades of the wind turbine generator based on the turbine rotation speed of the wind turbine generator to maintain the turbine rotation speed within a predetermined range is, Each time the pitch angle of the three blades of the wind turbine is adjusted, a first predetermined detection time interval is set to detect whether the turbine rotation speed is within the predetermined rotation speed range, The aforementioned predetermined rotational speed range refers to the range between the first rotational speed and the second rotational speed, When it is detected that the turbine rotation speed is less than the first rotation speed, the pitch angles of the three blades of the wind turbine are each reduced by a predetermined adjustment angle, If it is detected that the turbine rotation speed exceeds the second rotation speed, the pitch angles of the three blades of the wind turbine generator are each increased by a predetermined adjustment angle, and this includes the following: The flutter suppression method for a wind turbine generator according to claim 2, characterized in that the relationship between the first rotational speed and the second rotational speed satisfies 0 < first rotational speed < second rotational speed < 12 rpm.

4. The step of performing a pitch operation on the blades of the wind turbine based on a pitch angle sequence in a predetermined pitch control rule is: The three blades of the wind turbine are pitch-controlled to the first sequence value of the pitch angle sequence, The second step involves detecting whether the flutter of the wind turbine is suppressed at predetermined detection time intervals, In the case of NO, the pitch angle is controlled to the second sequence value of the pitch angle sequence by performing a pitch operation on the three blades of the wind turbine according to a predetermined pitch control rule. After the pitch operation, after an interval of the second predetermined detection time, it is detected again whether the flutter of the wind turbine generator is suppressed. If NO, the pitch angle is controlled to the next sequence value in the pitch angle sequence by continuing to perform a pitch operation on the three blades of the wind turbine according to the predetermined pitch control rule, The aforementioned predetermined pitch control rule is: The pitch angles of the three blades in the aforementioned pitch angle sequence increase or decrease sequentially, The difference between the maximum and minimum pitch angles of the same blade in the aforementioned pitch angle sequence exceeds the maximum value of the pitch angle interval span that causes flutter accumulation, The flutter suppression method for a wind turbine according to claim 2, further comprising the condition that 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 distance between pitch angle intervals that cause the accumulation of flutter.

5. The flutter suppression method for a wind turbine according to claim 4, characterized in that the maximum value of the span of the pitch angle intervals that cause the accumulation of flutter exceeds 60 degrees, and the minimum value of the distance between the pitch angle intervals that cause the accumulation of flutter is less than 35 degrees.

6. The determination of whether the flutter of the wind turbine is suppressed is made by: Collecting vibration signals from tower vibration sensors or blade vibration sensors located on wind turbines, Spectrum analysis is performed on the vibration signal, and the amplitude frequency components in the 0.2 Hz to 3.0 Hz band of the vibration signal are extracted as equivalent amplitudes. If the equivalent amplitude does not exceed a predetermined value, it is determined that the flutter of the wind turbine has been suppressed, and the range of the predetermined value is set to 0.004 m / s ２ <Predetermined value<0.1 m / s ２ A method for suppressing flutter in a wind turbine according to claim 1, characterized by including the following:

7. After the flutter of the wind turbine is suppressed, the method is performed. The further step includes controlling the three blades of the wind turbine to return them to the feathering position, The flutter suppression method for a wind turbine according to any one of claims 1 to 6, characterized in that the feathering position refers to a position where the pitch angle is 80 degrees or more and 95 degrees or less.

8. A flutter suppression device for a wind turbine, A calculation module for determining the nacelle wind direction angle between the orientation of the wind turbine nacelle and the wind direction, The system includes a decision module for determining a pitch control strategy that modifies the pitch angle based on the nacelle wind direction angle, The pitch control strategy includes a pitch control scheme based on rotational speed control and a pitch control scheme based on pitch sequence control. The pitch control scheme using rotational speed control includes maintaining the turbine rotational speed within a predetermined range by adjusting the pitch angle of the wind turbine blades based on the turbine rotational speed of the wind turbine until the flutter of the wind turbine is suppressed. A flutter suppression device for a wind turbine, characterized in that the pitch control scheme based on the pitch sequence includes performing a pitch operation on the blades of the wind turbine based on a pitch angle sequence in a predetermined pitch control rule until the flutter of the wind turbine is suppressed.

9. A control system for wind turbines, Equipped with a control device and a pitch drive system, The pitch drive system is used to receive commands from the control device and to perform pitch control on the blades of the wind turbine. A control system for a wind turbine, characterized in that the control device is used to perform the flutter suppression method for a wind turbine according to any one of claims 1 to 7, and to output a control command to the pitch drive system.

10. A wind turbine characterized by comprising the control system for the wind turbine described in claim 9.

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