JP2012107584A - Wind turbine and method for damping vibration of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wind turbine capable of exhibiting large vibration damping effect in a wide frequency band specific to the wind turbine.SOLUTION: The wind turbine has a TMD (tuned mass damper) adjusted to damp vibration in a specific frequency of the wind turbine and an AVC (active vibration control) adjusted to damp fluctuational frequency of a turbulence of wind flowing into the wind turbine and/or the vibration in the frequency of the rotational frequency wind turbine blades, and a pitch angle control section having a correct section for adjusting the vibration damping frequency of the AVC. The AVC is configured to obtain vibration damping force by changing the pitch angle of the wind turbine blades.

Description

  The present invention relates to a wind turbine and a vibration damping method therefor.

  As clean energy, wind turbines that generate electricity by converting wind energy into electric power have attracted attention. A windmill has a structure in which heavy objects such as windmill blades, gearboxes, and generators are installed above the tower, which is generally several tens of meters high. The induced vibration cannot be ignored. Such vibration increases the fatigue load of the structural material of the windmill and shortens the life of the windmill.

On the other hand, in high-rise buildings such as buildings, AMD (Active Mass Damper) is adopted to attenuate vibration caused by wind. However, AMD requires an actuator for driving the additional mass in addition to the additional mass, which increases cost and weight. In particular, when applied to a windmill, the weight of the upper portion of the tower is further increased, which is not preferable.
Patent Document 1 listed below discloses an invention in which an additional mass is reduced by combining a passive damper with AMD. However, since an actuator for driving the additional mass is still required, the increase in weight is not fundamentally solved.

  Patent Document 2 listed below discloses an invention for active damping of a wind turbine provided with a pitch angle control mechanism capable of controlling the pitch angle of the wind turbine blades without providing a special actuator for damping vibration. Specifically, a pitch angle command is output to the pitch angle control mechanism so as to obtain a thrust force for vibration control.

US Pat. No. 5,428,883 International Publication No. 2005/083266

As shown in FIG. 13, the vibration of the windmill is vibration caused by turbulent wind, vibration caused by rotor rotation speed (1N, 3N; N is rotation speed (3N is three blades)), The vibration caused by the natural frequency (1st, 2nd) of the windmill itself is dominant. In this case, it is conceivable that the rotor rotational speed component is reduced by balancing the wind turbine blades, and the wind turbulence component and the tower natural vibration component are reduced by active vibration suppression or a passive damper.
However, as shown in the figure, the wind turbine has a wide frequency band that needs to be damped, and has the following problems. That is, as shown in FIG. 13, in general, the peak level having a high damping effect and the frequency band exhibiting the damping effect are inversely related, so if a large damping effect is to be obtained, a narrow frequency band can be obtained. Inevitably (see curve L1), conversely, in order to obtain a wide frequency band, the peak level becomes low (see curve L2). Therefore, it is difficult to obtain a large damping effect in all the frequency bands of vibrations specific to the windmill.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a windmill and a vibration damping method that can exhibit a great vibration damping effect in a wide frequency band specific to the windmill.

In order to solve the above-mentioned problems, the wind turbine and its vibration damping method of the present invention employ the following means.
That is, the wind turbine according to the present invention includes a passive damper adjusted so as to attenuate vibrations at the natural frequency of the wind turbine, a fluctuation frequency of the turbulence of the wind flowing into the wind turbine, and / or the n-th order of the rotational speed of the wind turbine blade ( n is a natural number), and includes an active damper adjusted so as to attenuate vibration at a frequency, and an active damper control unit that adjusts a vibration suppression frequency of the active damper.

Since the natural frequency of the windmill is uniquely determined by the shape and physique of the windmill, the vibration at the natural frequency is attenuated by a passive damper that can be fixed at a specific frequency and can be damped.
On the other hand, the fluctuation frequency of the turbulence of the wind flowing into the windmill fluctuates depending on the wind conditions according to the weather, season, time, and the like. Further, the n-order frequency of the rotational speed of the wind turbine blade also varies depending on the rotational speed of the wind turbine blade. Therefore, for vibrations at these frequencies, an active damper (for example, AVC; Active Vibration Control) capable of dynamically changing the damping frequency by the active damper controller is used.
As described above, since the active damper and the passive damper are separately burdened with the corresponding frequencies, the damping effect of each damper can be effectively exhibited.

  Furthermore, in the wind turbine according to the present invention, the active damper obtains a damping force by changing a pitch angle of the wind turbine blade.

  An active damper that uses the wind energy by changing the pitch angle of the wind turbine blades and exhibits a damping action is adopted. In this case, finite wind energy is used as the damping force. In the present invention, since the active damper is concentrated and attenuated at a predetermined frequency, the vibration energy can be exerted effectively by using wind energy.

  Furthermore, the wind turbine according to the present invention includes an anemometer that detects a flow velocity of the wind flowing into the wind turbine, and the active damper control unit controls the active damper based on the flow velocity detected by the anemometer. And

  The active damper was controlled according to the fluctuation of the wind speed detected by the anemometer. Since the control is performed in accordance with the wind speed fluctuation that flows in in this way, it is possible to perform vibration suppression with higher responsiveness than in the case of performing vibration suppression after obtaining vibration actually generated in the wind turbine by an acceleration sensor or the like.

  Further, in the wind turbine of the present invention, the passive damper is a tuned mass damper, and the tuned mass damper uses a wind turbine component that is movable relative to the wind turbine body as an additional mass. And

As the passive damper, a tuned mass damper (TMD) is suitable. This is because a passive damper can be configured without adding any special addition by selecting an existing wind turbine component provided as an additional mass for exhibiting the function of the wind turbine, not for vibration suppression purposes. Because. Thereby, it is not necessary to increase the weight of the windmill for vibration control.
Wind turbine components selected as additional mass include, for example, a nacelle cover, transformer, ladder (lifting ladder), tower platform (scaffolding), and a platform suspended from the nacelle. And a turning module for turning the nacelle in the yaw direction.

  Furthermore, in the wind turbine according to the present invention, the passive damper is a tuned liquid damper, and the tuned liquid damper uses hydraulic oil or lubricating oil stored in the wind turbine body as an additional mass.

As the passive damper, a tuned liquid damper (TLD) is suitable. This is because a passive damper can be configured without adding a special additive by selecting hydraulic oil or lubricating oil stored in the wind turbine as the additional mass. Thereby, it is not necessary to increase the weight of the windmill for vibration control.
Examples of the hydraulic oil or machine oil selected as the additional mass include hydraulic oil in a reservoir tank of a hydraulic device, lubricating oil for a speed increaser, and the like.

  The wind turbine damping method of the present invention is a wind turbine damping method including a passive damper adjusted to attenuate vibrations at the natural frequency of the wind turbine and an active damper, and flows into the wind turbine. The damping frequency of the active damper is controlled so as to attenuate the vibration at the fluctuation frequency of wind turbulence and / or the n-th (n is a natural number) frequency of the rotational speed of the wind turbine blade.

Since the natural frequency of the windmill is uniquely determined by the shape and physique of the windmill, the vibration at the natural frequency is attenuated by a passive damper that can be fixed at a specific frequency and can be damped.
On the other hand, the fluctuation frequency of the turbulence of the wind flowing into the windmill fluctuates depending on the wind conditions according to the weather, season, time, and the like. Further, the n-order frequency of the rotational speed of the wind turbine blade also varies depending on the rotational speed of the wind turbine blade. Therefore, for vibrations at these frequencies, an active damper (for example, AVC; Active Vibration Control) capable of dynamically changing the damping frequency is used.
As described above, since the active damper and the passive damper are separately burdened with the corresponding frequencies, the damping effect of each damper can be effectively exhibited.

  Since the active damper and the passive damper are separately burdened with the corresponding frequencies, the damping effect of each damper can be effectively exhibited.

It is the figure which showed the basic idea of the vibration suppression method of the windmill of this invention. It is the figure which showed the method of changing a damping frequency according to a turbulence component of a wind. It is the figure which showed the method of changing a damping frequency according to the change of rotor rotation speed. It is the block diagram which showed the structure of AVC. It is the figure which showed the vibration model of TMD. It is the perspective view which showed one Embodiment which used the additional mass of TMD as the nacelle cover. The attachment structure of the nacelle cover of FIG. 6 is shown, (a) is a side view, (b) is a rear view. It is the enlarged view which showed the fixing | fixed part of a nacelle cover and a flame | frame, (a) shows the structure of this invention fixed using the elastic member, (b) shows the general structure fixed using the rigid member. It is the side view which showed one Embodiment which used the additional mass of TMD as the ladder. It is the side view which showed one Embodiment which used the additional mass of TMD as a platform. It is the side view which showed one Embodiment which used the additional mass of TMD as the cable. It is the side view which showed one Embodiment which used the additional mass of TMD as the lower module of a nacelle. It is the figure which showed the vibration which arises in a windmill with respect to the frequency.

Embodiments according to the present invention will be described below with reference to the drawings.
FIG. 1 shows the basic concept of vibration suppression of the present invention. The horizontal axis of the figure (a) shows frequency [Hz], and a vertical axis | shaft shows the vibration level [dB] in the nacelle installed in the upper part of the tower of a windmill. As shown in FIG. 5A, in order from the low frequency side, vibration due to the frequency component of the wind turbulence, vibration at the rotor rotational frequency (1N), vibration at the primary component (1st) of the natural frequency of the windmill itself, Vibrations at a rotational speed (3N) that is three times the rotor rotational speed and vibrations at the secondary component (2nd) of the natural frequency of the windmill itself appear. The relationship between the frequency at the rotor rotation speed (1N) and the primary natural frequency (1st) may be reversed depending on the natural frequency of the windmill itself. Further, the vibration appearing at the rotation speed (3N) that is three times the rotor rotation speed is due to the fact that there are three wind turbine blades.
The horizontal axis of FIG.1 (b) shows frequency [Hz] and a vertical axis | shaft shows attenuation amount [dB] by a damping device. As shown in the figure, in the present invention, the frequency component of wind turbulence (and / or the rotor) is adjusted by adjusting the primary natural frequency (1st) to function a passive damper (specifically, TMD). The active vibration damping (AVC; active damper) is made to function by adjusting to the 1N component of the rotational speed.
In particular, for active vibration suppression, as shown in FIG. 2, it is preferable to adjust the frequency band in accordance with fluctuations in wind turbulence components. Further, as shown in FIG. 3, in the active vibration suppression, it is preferable to adjust the frequency band according to the fluctuation of the rotor rotational speed (1N).

FIG. 4 shows a specific configuration for performing the above-described active vibration suppression. The active vibration suppression shown in the figure uses the same method as in Patent Document 2 above.
In the figure, the rotational output of the rotor 4 rotated by the wind turbine blade 3 is guided to the gearbox 7. The rotational output whose rotational speed is increased by the speed increaser 7 is guided to the power generation system 9 and converted into electrical output. The power generation output from the power generation system 9 is supplied to a system (not shown). Each wind turbine blade 3 is provided with a pitch angle control mechanism 11. By this pitch angle control mechanism, the pitch angle of the wind turbine blade 3 is appropriately changed between the fine side that receives the wind flowing into the wind turbine blade 3 and obtains rotational output and the feather side that receives the wind. Yes.
The pitch angle command value θ input to the pitch angle control mechanism 11 is generated by the pitch angle control unit 13. The pitch angle control unit 13 includes a pitch angle setting unit 15 that sets the pitch angle based on the power generation output value P output from the power generation system 9. The pitch angle setting unit 15 sets the pitch angle of the wind turbine blade 3 so as to obtain a desired output power value. The pitch angle set by the pitch angle setting unit 15 is sent to the correction unit 17.
The correction unit 17 corrects the pitch angle based on the wind turbulence frequency obtained from the wind turbulence information acquisition means 19 and outputs it as a pitch angle command value θ. Examples of the wind turbulence information acquisition unit 19 include an optical fiber strain measuring device that obtains load fluctuations of the wind turbine blade 3. Alternatively, a laser Doppler velocimeter or an ultrasonic Doppler velocimeter may be installed in the windmill, and the pitch angle may be feedforward controlled by measuring the wind speed upstream of the windmill. Thus, by acquiring the wind turbulence component, the pitch angle is changed so as to intensively attenuate the vibration in the frequency band of the wind turbulence component. Specifically, the pitch angle is controlled so as to generate a thrust force that counteracts tower vibration caused by wind turbulence components. Even when the frequency band of the wind turbulence component changes, the correction unit 17 dynamically changes the pitch angle according to the change.
Further, the correction unit 17 receives an output value from the rotor rotational speed acquisition means 21 that acquires the rotational speed of the rotor rotated by the wind turbine blade 3. By acquiring the rotor rotational speed in this way, the pitch angle is changed so as to intensively attenuate the vibration at the rotor rotational speed (1N). Specifically, the pitch angle is controlled so as to generate a thrust force that cancels the tower vibration caused by the rotation of the rotor. Even when the rotor rotational speed fluctuates, the correction unit 17 performs vibration suppression by dynamically changing the pitch angle in accordance with the change.
The active vibration suppression according to the present invention performs vibration suppression corresponding to only the wind turbulence component or only the rotor rotational speed (1N). However, when these frequency components are close to each other, or when a broader vibration suppression frequency band is allowed by reducing the peak level of the vibration suppression effect, vibration suppression may be performed so as to correspond to both.

FIG. 5 shows a TMD (Tuned Mass Damper) vibration model that is adjusted so as to suppress vibrations at the primary natural frequency (1st) of the windmill itself.
In the same figure, m1 shows the mass of a windmill and m2 shows the additional mass used for TMD. Moreover, y shows the displacement direction at the time of vibration.
The vibration model shown in FIG.
My "+ Cy '+ ky = F
Here, M, C, k, y, and F are represented by the following matrix.

In the present invention, the additional mass m2 represented by the above formula uses an existing wind turbine component that is provided not for the purpose of vibration suppression but for exhibiting the function of the wind turbine. Hereinafter, a specific example will be described.
6 to 8 show a case where the mass of the nacelle cover is used as the additional mass m2. As shown in FIG. 6, the nacelle cover 30 is attached to a frame 32 fixed to the upper end of the tower 2 so as to be displaceable.
FIG. 7 shows a structure for attaching the nacelle cover 30 to the frame 32. FIG. 4A is a side view, and FIG. 4B is a rear view of FIG. As shown in the figure, the frame 32 and the nacelle cover 30 are connected by a linear guide 34, so that the nacelle cover 30 can reciprocate with respect to the frame 32. A plurality of elastic members (rubber etc.) 36 serving as TMD spring elements and damping elements are provided between the frame 32 and the nacelle cover 30. As shown in FIG. 8, the elastic member 36 is preferably rubber inserted between the frame 32 and the nacelle cover 30. FIG. 8B shows a structure as a comparative example, and generally a rigid member 38 such as a metal is provided.

  FIG. 9 shows a case where the mass of a ladder (elevating ladder) 40 installed in the tower 2 of the windmill is used as the additional mass m2. The upper end of the ladder 40 is pin-supported freely at a predetermined fixed position 42 at the upper end of the tower 2. When the pin is supported, a predetermined elastic member (rubber or the like) is interposed to provide a TMD spring element and damping element. The lower end of the ladder 40 is not fixed and is a free end so that the ladder 40 swings around the upper end as a swing center. In addition, it is preferable to provide a stopper so that the ladder 40 does not collide with the wall portion of the tower 2 when the ladder 40 swings.

  FIG. 10 shows a case where the mass of the platform 44 in the tower 2 is used as the additional mass m2. The platform 44 is used as a scaffold for workers. As shown in the figure, the platform 44 has a hanging structure using a support member 45. The platform 44 swings around a fixed position 46 at the upper end of the support member 45. When the support member 45 is fixed, a predetermined elastic member (rubber or the like) is interposed to provide a TMD spring element and damping element.

  FIG. 11 shows a case where the mass of a part of the cable 50 extending from the nacelle 5 to the ground is used as the additional mass m2. Specifically, the mass of the cable 50 above the pulley 52 is used as the additional mass m2. In this case, the elasticity of the cable 50 itself is used as a TMD spring element and damping element.

FIG. 12 shows a case where the nacelle 5 is divided into upper and lower upper modules 5a and lower modules 5b and the mass of the lower module 5b is used as the additional mass m2.
A speed increaser, a generator, and the like are arranged in the upper module 5a. A yaw turning motor and a yaw brake for turning the nacelle 5 are arranged in the lower module 5b. The lower module 5b can be moved relative to the upper module 5a. Although not shown, an elastic member is arranged so as to give a TMD spring element and damping element when the upper module 5a and the lower module 5b move relative to each other.

  Although not shown, the transformer in the nacelle may be moved relative to the nacelle body, and the mass of the transformer may be used as the additional mass m2. Furthermore, in addition to the above, if it is a wind turbine component and has an appropriate weight as an additional mass, it can be used as an additional mass for TMD by installing it relative to the nacelle or tower. it can.

  Although not shown, a TLD (Tuned Liquid Damper) may be used instead of TMD. In this case, it is preferable to use hydraulic oil or lubricating oil stored in the nacelle as the additional mass. Specifically, hydraulic oil in a reservoir tank of a hydraulic device, lubricating oil for a speed increaser, and the like can be given.

As described above, according to the present embodiment, the following operational effects are obtained.
Since the natural frequency of the windmill is uniquely determined by the shape and physique of the windmill, the vibration at the natural frequency is attenuated by TMD (or TLD) that can be fixed at a specific frequency and can be damped.
On the other hand, the fluctuation frequency of the turbulence of the wind flowing into the windmill fluctuates depending on the wind conditions according to the weather, season, time, and the like. Further, the n-order frequency of the rotational speed of the wind turbine blade also varies depending on the rotational speed of the wind turbine blade. Therefore, for vibrations at these frequencies, AVC that can dynamically change the damping frequency is used.
In this way, TMD and AVC are separately burdened with corresponding frequencies, so that the damping effect of each damper can be effectively exhibited.

  By changing the pitch angle of the wind turbine blade 3, wind energy is used and AVC that exhibits a damping action is adopted. In this case, finite wind energy is used as the damping force. However, in this embodiment, since the AVC is concentrated and attenuated at a predetermined frequency, the wind energy is effectively used for damping. You can show your power.

  The AVC was controlled in accordance with fluctuations in wind speed detected by an anemometer such as an optical fiber strain meter or a laser Doppler velocimeter. Since the control is performed in accordance with the wind speed fluctuation that flows in in this way, it is possible to perform vibration suppression with higher responsiveness than in the case of performing vibration suppression after obtaining vibration actually generated in the wind turbine by an acceleration sensor or the like.

  In addition, by selecting an existing wind turbine component that is provided not for the purpose of vibration suppression but for exhibiting the function of the wind turbine as the additional mass, the TMD can be configured without adding a special additive. It is. Thereby, it is not necessary to increase the weight of the windmill for vibration control.

  By using the existing liquid present in the nacelle, the TLD can be constructed without adding any special adjuncts, so that it is not necessary to increase the weight of the windmill for vibration control.

2 Tower 3 Windmill blade 4 Rotor 5 Nacelle 7 Booster

Claims (6)

A passive damper tuned to damp vibrations at the natural frequency of the windmill;
An active damper adjusted to dampen vibrations at the fluctuation frequency of the turbulence of the wind flowing into the wind turbine and / or the n-th (n is a natural number) frequency of the rotation speed of the wind turbine blade;
An active damper controller that adjusts the vibration damping frequency of the active damper;
A windmill characterized by comprising.   The wind turbine according to claim 1, wherein the active damper obtains a damping force by changing a pitch angle of the wind turbine blade. Equipped with an anemometer that detects the flow velocity of the wind flowing into the windmill,
The wind turbine according to claim 1, wherein the active damper control unit controls the active damper based on a flow velocity detected by the anemometer. The passive damper is a tuned mass damper;
The wind turbine according to any one of claims 1 to 3, wherein the tuned mass damper uses a wind turbine component that is movable relative to the wind turbine body as an additional mass. The passive damper is a tuned liquid damper,
The wind turbine according to any one of claims 1 to 3, wherein the tuned liquid damper uses hydraulic oil or lubricating oil stored in the wind turbine body as an additional mass. A vibration damping method for a windmill comprising a passive damper adjusted to attenuate vibrations at the natural frequency of the windmill, and an active damper,
A wind turbine characterized by controlling the vibration damping frequency of the active damper so as to attenuate vibrations at the fluctuation frequency of the turbulence of the wind flowing into the wind turbine and / or the n-th (n is a natural number) frequency of the rotational speed of the wind turbine blade. Vibration control method.

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