JP2007064062A - Horizontal axis windmill - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To ensure a standby state wherein a rotor or blade trailing edges are drawn to the leeward in a storm regardless of with or without independent pitch control, to reduce occurrence of flutter by avoiding storm wind from the blade trailing edges by the standby state, thereby reducing design load in a storm of blades or the like, in an upwind type horizontal axis windmill having blades with low stiffness such as super large equipment. <P>SOLUTION: In the horizontal axis windmill, when a wind velocity exceeds a cutout wind velocity, all of blades 4a to 4c are brought into a feathering state (Fig. 1(a)). A nacelle 2 is rotated to change angles of them to be a fixed angle in a yaw angle range A and the state is maintained by a yaw brake (Fig. 1(b)). Next, all of the blades are brought into a reversed feathering state at the same time (Fig. 1(c)). Thereafter, all blade is kept to be in the reversed feathering state until returning to an operating mode, and the yaw brake is controlled to be a predetermined brake value allowing yaw-rotation of the nacelle 2 by a wind force. When yaw torque exceeding the yaw brake is loaded on the windmill by the wind force, the rotor and the blade trailing edges are drawn to the leeward (Fig. 1(d)). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to standby in a storm in an upwind type horizontal axis wind turbine.

As is well known, so-called horizontal axis wind turbines are widely used for commercial purposes. A general horizontal axis wind turbine supports the rotor via a rotor in which at least two blades are attached radially from a hub, and a main shaft that is connected to the hub and extends in a substantially horizontal direction. It has a nacelle and a tower that is installed in a substantially vertical direction and supports the nacelle in a yaw-rotatable manner.
In addition, it has also been conventionally performed to provide control means such as a yaw driving means that can freely control yaw rotation of the nacelle, a yaw brake that brakes the yaw rotation, and a main shaft brake that brakes the rotation of the rotor in the horizontal axis wind turbine. ing.
Almost all commercial wind turbines today have an upwind horizontal axis wind turbine configuration. The upwind type horizontal axis wind turbine is a horizontal axis wind turbine configured to generate electricity by rotating a rotor disposed on the windward side of the tower.

  Usually, the design strength of a windmill is greatly influenced by the load received during a standby state during a storm. It is necessary to set the windmill load during a storm assuming that a power outage will also occur. Hereinafter, prior arts 1 to 6 relating to a standby method for a horizontal axis wind turbine will be described.

[Prior art 1]
Prior art 1 is a general upwind / stall control wind turbine, which is configured to wait for a storm by fixing a main shaft with a brake. Basically, the yaw is fixed during standby. Some of them perform yaw control to reduce the load by making the rotor parallel to the wind direction. Even if yaw control is possible, if the power necessary for yaw control is cut off or if any device related to yaw control breaks down, there is a possibility of receiving a storm from all directions. Therefore, it is necessary to design the storm from all directions. In general, in the case of a stall controller, a large load is generated during a storm from the front and back.

[Prior art 2]
Prior art 2 is a general upwind pitch controller, which idles the rotor, fixes the yaw, and waits in a storm. Some pitch controllers use yaw control to direct the rotor to the windward to reduce the load, but this has a power supply necessary for yaw control and each device functions without failure. This is a prerequisite. In general, in the case of a pitch controller, a large load is generated during a side wind and a storm from the front / back. Model A shown in FIG. 3 corresponds to the standby mode of Conventional Technique 2.

[Prior art 3]
Prior art 3 is an upwind pitch controller that secures the feathers of all wings, then reverses the nacelle azimuth by about 180 [deg] by yaw control, holds it with a weak yaw brake, and waits in a storm. (For example, see Non-Patent Document 1). Thereby, at the time of a storm, a rotor can go downwind and the load to a tower can be reduced. The standby mode of the prior art 3 is similar to the prior art 5 in appearance. The model B shown in FIG. 3 corresponds to the standby mode of the prior arts 3 and 5.

[Prior Art 4]
Prior art 4 is a downwind windmill / pitch controller, which secures the feathers of all the blades, idles the rotor, and stands by during a storm as free yaw. Thereby, at the time of a storm, a rotor can wind downwind and the load which acts on a tower top part can be reduced. The standby mode of the prior art 4 is similar in appearance to the embodiment of the present invention and the prior art 6. The model C shown in FIG. 3 is a standby mode of the embodiment of the present invention, and the standby modes of the prior arts 4 and 6 also correspond to this.

[Prior art 5]
Prior art 5 is a downwind windmill / pitch controller described in Patent Document 1, and after securing the feathers of all the blades, the pitch angle is changed by about 180 [deg] for each blade, and a storm with free yaw It is something that waits sometimes. When receiving wind from the trailing edge of the blade, the maximum lift coefficient is greatly reduced when receiving wind from the trailing edge, and the yaw holding torque is also small, so the load generated at other parts is also small. . The standby mode of the prior art 5 is the same as that of the prior art 3 in appearance. The model B shown in FIG. 3 corresponds to the standby mode of the prior arts 3 and 5.

[Prior Art 6]
Prior art 6 is an upwind windmill / pitch controller described in Patent Document 2, and after securing the feathers of all the blades, the pitch angle is changed by about 180 [deg] for each blade, and a storm with free yaw It is something that waits sometimes. The wind is not received from the trailing edge of the blade, and the load is reduced. This is effective for low-rigid wings such as ultra-large aircraft. The standby mode of the prior art 6 is similar in appearance to the embodiment of the present invention and the prior art 4. The model C shown in FIG. 3 is a standby mode of the embodiment of the present invention, and the standby modes of the prior arts 4 and 6 also correspond to this.
Japanese Patent Application No. 2004-193271 Japanese Patent Application No. 2005-159848 Masaaki Shibata, Yoshiyuki Hayashi, “New Concept for Reduction of Design Load”, 25th Memorial Wind Energy Utilization Symposium, November 20, 2003, p. 225-227

Even with a 2 MW class windmill, the strength problem can be avoided if it is well designed according to the scale of the windmill using the above-mentioned conventional technology. However, as the size of the blade further increases in the future, the rigidity of the blade will further decrease, and the natural frequency will decrease. The problem of becoming is expected.
In the case of having the low-rigid wings as described above, the upwind horizontal axis wind turbines of the prior arts 1 to 3 cannot avoid the storm from the vicinity of the wing trailing edge regardless of the storm standby mode, and flutter It is more likely to occur. There are two types of flutter modes that are expected to occur:
Stall flutter: The lift gradient with respect to the angle of attack becomes negative in the stall region of the wing, and the aerodynamic term gives a negative damping effect in this region, increasing the instability tendency. This occurs even on wings with high torsional rigidity.
Bending / twisting flutter: Since a wing is an asymmetrical and long structure, twisting occurs in bending. In particular, when a storm from the vicinity of the trailing edge of the blade is received, the blade is bent under a load. However, since the torsion is coupled to this, the angle of attack flowing into the blade is changed, and it tends to be unstable. This rarely occurs on wings with high torsional rigidity.

  The upwind horizontal axis wind turbine of the prior art 6 provides a solution to the above problem associated with the increase in size. However, the upwind type horizontal axis wind turbine of the prior art 6 requires an independent pitch control device for controlling the blade pitch angle independently and a complicated steering sequence. Therefore, the solution to the above problem is limited to an upwind horizontal axis wind turbine having an independent pitch control device and capable of a complicated steering sequence.

  The present invention has been made in view of the above-described problems in the prior art. In an upwind type horizontal axis wind turbine, the presence / absence of an independent pitch control device for independently controlling the pitch angle of the blade, and complicated steering Regardless of whether or not the sequence is possible, it is possible to secure a standby mode in which the rotor and blade trailing edge winds down in the wind during a storm. This standby mode avoids storms from the blade trailing edge and reduces flutter generation. The object is to reduce the load.

The invention according to claim 1 for solving the above-described problems includes a rotor having a hub and at least two blades;
A nacelle that pivotally supports the rotor via a main shaft connected to the hub;
A tower that supports the nacelle in a yaw-rotating manner;
A pitch control device for controlling the pitch angle of the blade;
A yaw control device for controlling the yaw rotation of the nacelle,
When the wind speed is less than or equal to a predetermined value, the rotor is placed upwind from the tower under the control of the yaw control device, and wind power is used through rotation of the rotor, and the operation mode is entered when the wind speed exceeds the predetermined value. In an upwind type horizontal axis wind turbine having a standby mode for preparing and waiting,
(1) The pitch control device includes a first step in which all the blades are feathered, a third step in which all the blades are reversed feathers after the first step, and the operation mode after the third step. Holding all the blades in a reverse feather state until the return of
(2) The yaw control device controls a yaw angle of the nacelle within a predetermined yaw angle range that avoids front wind and back wind with respect to the rotor in synchronization with the third step; A control operation comprising a step of controlling the yaw brake to a braking value that allows yaw rotation by the torque around the yaw axis that is loaded on the nacelle by wind force from the second step to the return to the operation mode,
A horizontal axis wind turbine characterized in that the control operations (1) and (2) are executed as the standby mode.

  The invention according to claim 2 is characterized in that the predetermined yaw angle range is +75 to +110 [deg] or −75 to −110 [deg] with respect to the windward. It is an axial windmill.

  The invention according to claim 3 is the horizontal axis wind turbine according to claim 1, wherein in the third step, the pitch control device simultaneously turns all the blades into reverse feathers.

According to the present invention, when the wind speed exceeds a predetermined value and when waiting for the operation of the wind turbine for power generation or the like, the load load due to the storm is reduced by making all the blades feather in the first step. Can do. By this first step, the trailing edge of all the blades faces the tower side. By the third step, all the blades are inverted feathers so that the leading edge of the blade faces the tower side. .
In the second step, the nacelle yaw angle is controlled within a predetermined yaw angle range that avoids the front wind and back wind with respect to the rotor in synchronization with the third step. In the process of changing the pitch of the feather, the rotor rotation axis deviates from the wind direction, so that it is possible to suppress the rotor over-rotation due to the storm and the load load due to the storm.
The predetermined yaw angle range is a range including ± 90 [deg], and is preferably a narrower range including ± 90 [deg] in order to avoid a storm, but if it is too narrow, it takes a long time to converge control. Cost. For example, it can be realized by setting +75 to +110 [deg] or −75 to −110 [deg] with respect to the windward, and a sufficient storm avoidance effect can be obtained.
As described above, while performing the first to third steps, avoiding the storm, and after the leading edge of the blade has turned to the tower side, keep all the blades in the inverted feather state until the operation mode returns. At the same time, the yaw brake is controlled to a braking value that allows yaw rotation by the torque around the yaw axis loaded on the nacelle by the wind force. Therefore, as long as the strong wind continues, the nacelle receives a cross wind or a slant wind, generates torque around the yaw axis that is loaded on the nacelle by the wind force, and the nacelle yaw rotates so that the rotor is arranged leeward of the tower. Can be blown downwind from the tower.
When the rotor is placed leeward from the tower, the leading edge of all the blades is already facing the tower side and holds it, so all the blades receive wind from the leading edge and flutter Thus, the load applied to the blade can be reduced.
As described above, it is possible to secure a standby mode in which the rotor and the trailing edge of the blade are leeward while avoiding a storm. This standby mode avoids a storm from the trailing edge of the blade and reduces the occurrence of flutter. There is an effect that the design load can be reduced.

  Preferably, in the third step, the pitch control device simultaneously turns all the blades into reverse feathers. This is because all the blades can be quickly shifted to the inverted feather state. It can also be implemented in a wind turbine that does not have an independent pitch control device and that can control the pitch angle of the blades only in a lump. In this case, a complicated sequence for steering the pitch angle one by one is not required.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The following is one embodiment of the present invention and does not limit the present invention. FIG. 1 is a plan view of an upwind horizontal axis wind turbine according to this embodiment as viewed from above.

As shown in FIG. 1, the horizontal axis windmill of this embodiment is provided with the tower 1, the nacelle 2, the hub 3, and the three blades 4a-4c.
The nacelle 2 pivotally supports a rotor composed of the hub 3 and blades 4a to 4c via a main shaft (not shown) connected to the hub 3. The tower 1 supports the nacelle 2 so that it can rotate freely.
An anemometer and an anemometer (not shown) are attached to the outer surface of the nacelle 2.

  Inside the nacelle 2 are housed power transmission devices such as a speed increaser, a generator, and a main shaft brake (not shown), and a main shaft is coupled to each of these power transmission devices.

  The main shaft has a tip protruding outside the nacelle 2, and a rotor is attached to the tip of the main shaft so as to rotate together with the main shaft.

  The rotor has a hub 3 connected to the main shaft at the center, and three blades 4 a to 4 c are radially attached to the circumferential surface of the hub 3 in the rotation direction. In addition, the blade shape of the blades 4a to 4c is formed asymmetrically.

FIG. 2A is a block diagram showing a portion related to the present case in the configuration of the control unit mounted on the upwind type horizontal axis wind turbine of the present embodiment.
As shown in FIG. 2A, the control unit of the horizontal axis wind turbine according to the present embodiment includes an anemometer 10, an anemometer 13, a control device 16, a pitch driving device 11, and a yaw driving device 14. The control device 16 includes a pitch control device 12 and a yaw control device 15.

  The yaw driving device 14 includes a yaw brake (not shown) that detects the yaw angle of the nacelle 2 and drives the yaw rotation and brakes the yaw rotation. The yaw control device 15 gives a control signal to the yaw drive device 14 to control the yaw angle of the nacelle 2.

The pitch driving device 11 rotationally drives the pitch angles of the blades 4a to 4c. The pitch control device 12 gives a control signal to the pitch driving device 11 to control the pitch angles of the blades 4a to 4c. Each blade 4a-4c is freely controlled at least 180 degrees.
The pitch control of the blades 4a to 4c may be controllable independently for each blade or may be controllable only for all the blades. In order to carry out the present invention, it is not necessary to be able to control each blade independently, and it is sufficient that all the blades can be controlled collectively if they can be rotated 180 degrees. In the latter case, the configuration of the machine and the control device is simplified. Of course, the present invention can be applied even if the blades can be controlled independently.
Note that the pitch angle is the angle at which the blade is attached to the hub, and in this paper, the angle at which the efficiency is maximum is 0 [deg].

FIG. 2B is a diagram showing an over-rotation existence area on the yaw angle-pitch angle plane coordinates and a control step for avoiding this. As shown in FIG. 2 (b), the rotor rotates at 20 [rpm] or more under a wind condition of 40 [m / sec] on a plane coordinate with the horizontal axis as the yaw angle and the vertical axis as the pitch angle. The reaching over-rotation existence areas B1 and B2 are distributed. In the present embodiment based on FIG. 2 (b), +75 to +110 [deg] or −75 to −110 [deg] avoiding the over-rotation existence regions B1 and B2 is determined as the yaw angle range A, as follows: Perform standby mode. In the yaw angle range A, no excessive rotation is reached at any pitch angle.
At a pitch angle of 90 [deg], the trailing edges of the blades 4a to 4c face the tower 1 side, and at a pitch angle of -90 [deg], the leading edges of the blades 4a to 4c face the tower 1 side. At a yaw angle of 0 [deg], the rotor is upwind of the tower 1 and receives wind from the front.

  In general, in wind power generation for commercial use, there is a wind speed band suitable for power generation in consideration of mechanical strength, power generation efficiency, and safety, and power generation is not performed in a wind speed region exceeding the upper limit cut-out wind speed. In order to avoid the storm, the vehicle is controlled to stand by in a posture that can reduce the wind load as much as possible. Hereinafter, the operation mode and standby mode of the horizontal axis windmill of this embodiment will be described.

[Operation mode]
In the wind speed band suitable for power generation, the yaw control device 15 controls the rotor based on the wind direction detected by the anemometer 10 and arranges the rotor on the wind from the tower 1, and the pitch is determined based on the wind speed detected by the anemometer 13, the rotor rotational speed, and the like. The control device 12 controls the blades 4a to 4c at an appropriate pitch angle, and the rotor receives wind to rotate. The rotational force of the rotor is transmitted to the main shaft connected to the hub 3, coupled to the main shaft and transmitted to the generator housed in the nacelle 2, so that the kinetic energy due to the rotational motion is converted into electric energy. Converted. When the yaw driving device 14 receives the control signal from the yaw control device 15 and rotates the nacelle 2, the yaw brake is released or lightened, and when the nacelle 2 is held in a certain direction, the yaw brake torque is maximized. To.
The range in which the pitch angle and yaw angle exist in the operation mode of the upwind wind turbine is approximately the operation region R in FIG.

(Standby mode)
When the anemometer 13 detects that the wind speed exceeds the cut-out wind speed (for example, 25 [m / sec]) during a storm such as a typhoon, the pitch control device 12 makes all the blades 4a to 4c feather. (First step S1). The rotor stops and power generation is interrupted. Thereby, the wind load acting on the blades 4a to 4c and the tower 1 is reduced.

Next, the yaw control device 15 rotates the nacelle 2 to change the angle to a constant angle within the yaw angle range A, and holds the yaw angle of the constant angle nacelle 2 with the yaw brake (second step S2).
Next, in a state where the yaw angle of the nacelle 2 is maintained within the yaw angle range A, the pitch control device 12 simultaneously turns all the blades 4a to 4c into reverse feathers (third step S3).
The pitch control device 12 holds all the blades 4a to 4c in the inverted feather state from the third step S3 to the return of the operation mode. The yaw control device 15 controls the yaw brake to a braking value (braking force) that allows yaw rotation by the torque around the yaw axis that is loaded on the nacelle 2 by the wind force from the second step S2 to the return of the operation mode.
This braking value is set lower than the braking value when the nacelle 2 is held in a certain direction. Further, this braking value is set to a high value so that the nacelle 2 does not excessively yaw rotate when a wind exceeding the cutout wind speed is assumed. This braking value may vary according to the yaw rotation of the nacelle 2. For example, even if the torque around the yaw axis applied to the nacelle 2 by the wind force is small, the nacelle 2 is reduced to allow yaw rotation, while it is large to limit the angular velocity of the nacelle 2 yaw rotation below a certain level. It may vary depending on what is done.

Here, referring to FIG. 1 again, the execution of the above control operation and the wind turbine operation associated therewith will be described.
First, as shown in FIG. 1A, all the blades 4a to 4c become feathers by the execution of the first step S1, and the rotation of the rotor is stopped.

  Next, by the second step S2, the windmill assumes the posture shown in FIG. That is, the yaw angle of the nacelle 2 is approximately 90 [deg] with respect to the wind direction, and the rotor rotation surface is substantially parallel to the wind direction. In this posture, even if the pitch of the blade is cut, a large lift does not occur. In the second step S2, the nacelle 2 may be rotated to either side. FIG. 1B shows a state in which the nacelle 2 is rotated clockwise as viewed from above and is stored in the yaw angle range A of +75 to +110 [deg]. Whether to rotate clockwise or counterclockwise may be set in advance, but it is preferable to select and determine a rotation direction that can shift to the yaw angle range A in the shortest time at the start of the second step S2.

  Next, in the third step, the blades 4a to 4c are simultaneously turned into inverted feathers as shown in FIG. In this process, a large lift is not generated, and the reverse feather can be safely performed without over-rotating the rotor.

Thereafter, the state of the reverse feather is maintained until the operation mode is restored, and the yaw brake is controlled to a braking value that allows yaw rotation by the torque around the yaw axis loaded on the nacelle 2 by the wind force. If the torque around the yaw axis loaded on the nacelle 2 by the wind force is larger than the yaw brake torque, the nacelle 2 rotates, and the rotor is arranged on the leeward side of the tower 1 as shown in FIG. Go to the leeward side of 1. As a result, it is possible to secure a standby mode in which the trailing edges of the rotor and the blades 4a to 4c go to the leeward, and this standby mode avoids storms from the trailing edge of the blades and reduces the occurrence of flutter. Can be reduced.
By setting the braking value of the yaw brake to be relatively high, the nacelle 2 can be kept on standby without yaw rotation when the yaw torque load due to the wind is relatively small even if the wind speed exceeds the cut-out wind speed. In this case, if the wind direction does not change, the standby state shown in FIG. 1 (c) is maintained. In this case, too much rotation of the rotor does not occur and the wind speed is relatively low, so that the load on the wind turbine can be kept small. Even if the nacelle 2 changes the wind direction without following the wind direction, as will be understood from FIG. 2 (b), the rotor does not enter the over-rotation existence regions B1 and B2, so the rotor does not over-rotate and the wind speed Since the load is relatively low, the load on the wind turbine can be kept small.
On the other hand, by setting the braking value of the yaw brake to be relatively low, if the wind speed exceeds the cut-out wind speed, the nacelle 2 can stand by in a manner that follows the wind direction.

  When the anemometer 13 detects a wind speed equal to or lower than the cut-out wind speed for a certain period, the operation mode is restored. The yaw control device 15 rotates the nacelle 2 to make the rotor face upwind. For example, if the windmill is in the state shown in FIG. 1D when returning to the operation mode, the yaw control device 15 first rotates the nacelle 2 by 180 [deg] to direct the rotor to the windward. Further, for example, if the windmill is in the state of FIG. 1C when returning to the operation mode, the yaw control device 15 first rotates the nacelle 2 90 [deg] counterclockwise to bring the rotor upwind. To go.

Further, a description will be added with reference to the yaw angle-pitch angle plane coordinates of FIG.
The coordinates (yaw angle, pitch angle) are approximately in the operation region R during the operation mode. By executing the first step S1 in the standby mode, the coordinates shift to the point P1 or its surroundings. Since the first step S1 can instantaneously reduce the wind load on the rotor, it is preferable that the first step S1 is executed immediately upon detection of the cutout wind speed.

  Next, by the execution of the second step S2, the coordinates shift to the point P2 or its surroundings. As can be seen from FIG. 2 (b), even if the second step S2 is executed from the operation region R, it is possible to leave the over-rotation existence region B1. In the present embodiment, the control flow starts the second step S2 after the end of the first step S1, but regardless of this, the second step S2 may also be executed immediately upon detection of the cutout wind speed. That is, the first step S1 and the second step S2 may be started at the same time, or the second step S2 may be started before the completion of the first step S1, so that there is a period in which both proceed simultaneously. .

Next, by the execution of the third step S3, the coordinates shift to the point P3 or its surroundings. At this time, it is important not to enter the over-rotation existence areas B1 and B2, and it is also important to make a detour as far as possible from the over-rotation existence areas B1 and B2. This is realized by the synchronization of the second step S2 and the third step S3. In the present embodiment, the nacelle 2 is rotated to a target constant angle within the yaw angle range A in the first half of the step change process of the second step S2, and the angle of the nacelle 2 is adjusted to the constant angle in the second half holding process. A control flow is adopted in which the third step S3 is executed during the holding process. The second step S2 ends at the same time as or after the completion of the third step S3 and weakens the yaw brake. Further, the yaw angle range A is set to a constant range regardless of the pitch angle. According to the present embodiment, it is possible to make a detour away from the over-rotation existence areas B1 and B2 and move to the point P3 or its surroundings, which is a preferred embodiment.
Regardless of this, the third step S3 may be executed even during the yaw angle change in the second step S2, or a region outside the over-rotation existence regions B1 and B2 (and a region where the rotor rotation is further weakened) is selected. In this way, the yaw angle and pitch angle may be varied and controlled simultaneously. Further, the yaw angle range A may be determined so as to vary depending on the pitch angle. The second step S2 may be ended slightly before the completion of the third step S3 to weaken the yaw brake. What is required is to avoid the over-rotation existence areas B1 and B2 (preferably avoid as far as possible) and shift the yaw angle and pitch angle from the point P1 or the surrounding area to the point P3 or the surrounding area. The present invention is not limited to this embodiment. It is preferable to pass the middle between the over-rotation existence area B1 and the over-rotation existence area B2.

  Thereafter, if the yaw brake is controlled to a braking value that allows yaw rotation by the torque around the yaw axis loaded on the nacelle 2 by wind force, and the torque around the yaw axis loaded on the nacelle 2 by wind force is greater than the yaw brake torque. As shown by an arrow D in FIG. 2 (b), the nacelle 2 is rotated and the rotor is arranged on the leeward side. If the strong wind that rotates the nacelle 2 continues, the rotor will go leeward. In FIG. 2 (b), the coordinates of this windmill are approximately in the standby area W, and the windmill stops the storm in this standby mode. Wait for.

  As described above, according to the horizontal axis wind turbine of the present embodiment, even without an independent pitch control device and a complicated steering sequence, it is possible to ensure a standby mode in which the rotor and the blade trailing edge go to the lee while avoiding a storm, With this standby mode, it is possible to avoid the storm from the trailing edge of the blade and reduce the occurrence of flutter, thereby reducing the design load during the storm such as the blade.

  Since the rotor is in a standby mode in which the rotor winds downwind during a storm, even if the wind direction changes, the nacelle 2 rotates yaw so that the rotor is located on the leeward side, and thus acts on the blades 4a to 4c and the tower 1. The load can be reduced while releasing the load. Therefore, for example, in the case of a storm such as a typhoon, the rotor is disposed on the leeward side of the tower 1 without requiring special control means for maintaining the attitude of the horizontal axis wind turbine, and the load received by the wind can be minimized. it can. In addition, the design strength of the horizontal axis wind turbine can be greatly relaxed, the degree of freedom in design can be increased, and the cost can be reduced.

  Further, according to the horizontal axis wind turbine of the present embodiment, for example, in the case of a storm such as a typhoon, first, the wind acting on each blade 4a to 4c is set by setting the pitch angle of all the blades 4a to 4c to a feather state. The drag due to can be reduced. As a result, the load acting on the blades 4a to 4c and the tower 1 can be reduced.

  In addition, since the blades 4a to 4c feathered by the pitch control device 12 are shifted to a predetermined yaw angle range that avoids the front wind and the back wind with respect to the rotor, the pitch angle is simultaneously reversed feathers in this way. An excessive load is applied to the blades 4a to 4c and the tower 1 in the case where all the blades are reversed at the same time in a state where the rotor may receive a front wind or a back wind without performing proper yaw control. The risk of doing this can be avoided more reliably. As a result, it is possible to prevent excessive drag and lift from being generated in the blades 4a to 4c, and to effectively prevent the rotor from over-rotating.

In order to verify the occurrence of flutter due to standby mode, assuming that the blades are larger, models A, B, and C with greatly reduced blade rigidity are typically used for wind turbines with a diameter of 80 m (equivalent to 2 MW) that do not generate flutter. Created. The conditions and standby postures of models A, B, and C are shown in the table shown in FIG.
For each of models A, B, and C, the nacelle azimuth angle (FIG. 5), rotor rotational speed (FIG. 6), blade twist displacement (FIG. 7), and blade root flap bending (FIG. 4) shown in FIG. 8) Blade root torque (FIG. 9), yaw torque (FIG. 10), and yaw horizontal force (FIG. 11) were analyzed and output as a graph. Moreover, the main points of the analysis results, the distribution range, and the evaluation are described in the table shown in FIG.

  As described in the table shown in FIG. 3, the model A corresponds to the standby mode of the related art 2. Model B corresponds to the standby mode of the prior arts 3 and 5. Model C is the standby mode of the embodiment of the present invention, and the standby modes of the prior arts 4 and 6 also correspond to this.

  The model C, which is the standby mode of the embodiment of the present invention, has a good load reducing effect with respect to the wing flap bending / twisting and the yaw horizontal force. Further, the yaw torque is greatly improved as compared with a normal upwind machine (model A). The following items are evaluated one by one.

(1) Nacelle azimuth (see Fig. 5)
The models B and C that basically slide the yaw follow the wind direction. In the model B in which the trailing edge faces upwind, the blades vibrate in the first half (0 to 150 [sec]), and the yaw is also swung.

(2) Rotational speed (see Fig. 6)
In the models B and C that slide the yaw, the rotor basically swings slowly, but in the model B with the trailing edge facing the windward, there is blade vibration in the first half (0 to 150 [sec]). The rotor is also swung to this.

(3) Blade torsional displacement (see Fig. 7)
The same evaluation as the blade root torque applies.
(4) Blade root flap bending (see Fig. 8)
In general, there is a swing of a load accompanying rotor rotation. The first half (0 to 150 [sec]) of model B vibrates with a short period.

(5) Blade root torque (see Fig. 9)
In general, there is a swing of a load accompanying rotor rotation. A large torque is generated when storms are received from the trailing edge of the rotor, such as the first half of model B (0 to 150 [sec]) and the vicinity of 200 seconds of model A. Usually, since it is unacceptable for the pitch mechanism to be twisted back, the structure of the pitch mechanism and the blade needs to withstand this.

(6) Yaw torque (See Fig. 10)
In the models B and C that slide the yaw, the amplitude of the yaw torque is limited to a small value, and when it deviates from this, the load is released by the yaw slipping. In the models B and C, the load is significantly reduced as compared with the case of the model A with yaw holding.

(7) Yaw horizontal force (see Fig. 11)
Yaw horizontal force greatly contributes to the design of towers and foundations. In the models B and C that slide the yaw, there is a tendency to reduce the load basically, but in the model B that receives the wind from the trailing edge, a large vibration is generated and the load is increased. This tendency to reverse is seen when the blade stiffness is significantly low.

It is the top view which looked at the upwind type horizontal axis windmill of one Embodiment of this invention from the top. (a) is a block diagram showing a configuration of a control unit mounted on an upwind type horizontal axis wind turbine according to an embodiment of the present invention. (b) is the figure which showed the over-rotation existence area on a yaw angle-pitch angle plane coordinate, and the control step which avoids this. It is the table | surface which described the conditions and analysis result of model A, B, C which concern on this invention or the standby form of a prior art. It is a graph which shows the wind condition which concerns on the conditions of analysis. It is a graph which shows the analysis result of a nacelle azimuth. It is a graph which shows the analysis result of a rotor rotational speed. It is a graph which shows the analysis result of blade torsion displacement. It is a graph which shows the analysis result of a blade root flap bending. It is a graph which shows the analysis result of a blade root torque. It is a graph which shows the analysis result of yaw torque. It is a graph which shows the analysis result of a yaw horizontal force.

Explanation of symbols

1 Tower 2 Nacelle 3 Hub 4a, 4b, 4c Blade

Claims (3)

A rotor having a hub and at least two or more blades;
A nacelle that pivotally supports the rotor via a main shaft connected to the hub;
A tower that supports the nacelle in a yaw-rotating manner;
A pitch control device for controlling the pitch angle of the blade;
A yaw control device for controlling the yaw rotation of the nacelle,
When the wind speed is less than or equal to a predetermined value, the rotor is placed upwind from the tower under the control of the yaw control device, and wind power is used through rotation of the rotor, and the operation mode is entered when the wind speed exceeds the predetermined value. In an upwind type horizontal axis wind turbine having a standby mode for preparing and waiting,
(1) The pitch control device includes a first step in which all the blades are feathered, a third step in which all the blades are reversed feathers after the first step, and the operation mode after the third step. Holding all the blades in a reverse feather state until the return of
(2) The yaw control device controls a yaw angle of the nacelle within a predetermined yaw angle range that avoids front wind and back wind with respect to the rotor in synchronization with the third step; A control operation comprising a step of controlling the yaw brake to a braking value that allows yaw rotation by the torque around the yaw axis that is loaded on the nacelle by wind force from the second step to the return to the operation mode,
The horizontal axis wind turbine characterized by executing the control operations (1) and (2) as the standby mode.   The horizontal axis wind turbine according to claim 1, wherein the predetermined yaw angle range is +75 to +110 [deg] or -75 to -110 [deg] with respect to the windward.   2. The horizontal axis wind turbine according to claim 1, wherein in the third step, the pitch control device simultaneously turns all the blades into reverse feathers. 3.

Images