Wind turbine generator and method for controlling wind turbine generator

Abstract

To improve a facility utilization rate by securing followability to a wind direction while preventing an excessive load from being generated in each apparatus and the apparatus from being damaged even when a strong wind is received during yaw control.SOLUTION: A wind turbine generator according to the present invention is a downwind wind turbine generator that includes a rotor, a nacelle that supports the rotor, a tower that supports the nacelle in a yaw-rotatable manner, a driving device that yaw-rotates the nacelle, a braking device that brakes yaw rotation of the nacelle, an anemoscope / anemometer, and a control device that controls the driving device and the braking device based on a wind condition measured by the anemoscope / anemometer, and generates electric power with the rotor disposed on a leeward side with respect to the nacelle. When a wind condition satisfies a predetermined condition, the control device releases the braking device to be in a free yaw state while continuing power generation, and starts the driving device when a state in which the yaw rotation speed is smaller than a first value continues for a predetermined time in the free yaw state.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a wind turbine generator and a method for controlling the wind turbine generator. [Background technology]

[0002] In a typical wind turbine, a yaw drive unit is installed at the connection between the top of the tower and the nacelle to control the rotor's orientation, i.e., yaw control, so that the rotor, i.e., the multiple blades and hub, can receive the maximum amount of wind. Yaw control involves using the yaw drive unit to orient the rotor face directly toward the wind when there is a deviation between the wind direction and the rotor's orientation. During yaw control, if there is a sudden change in wind speed or direction, the wind load can cause excessive loads and stresses on each piece of equipment, potentially resulting in damage to the equipment.

[0003] Patent Document 1 describes a method for operating a wind turbine that includes a support erected on an installation surface such as the ground or a ship, a nacelle supported so as to be rotatable in a horizontal direction, a rotor with multiple blades that is rotated by wind power, a generator housed within the nacelle and connected to the rotor, a rotation drive mechanism that rotates the wind turbine body, and a brake device that suppresses the rotation of the wind turbine body, and in which the rotor to which the generator is connected rotates due to wind power received by the blades, by rotating the wind turbine body at least until the rotor is on the downwind side, and then allowing the rotation of the wind turbine body to naturally follow the wind direction. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-146858 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the technology described in Patent Document 1 is intended for upwind wind turbines that generate power with the rotor facing upwind, and does not assume that the rotor will be moved downwind to generate power. In a downwind wind turbine that is generating power, if the technology described in Patent Document 1 is used to make the rotation of the wind turbine body naturally follow the wind direction, the wind direction may not be stably followed, resulting in a decrease in the capacity factor.

[0006] It is desirable to establish a control method for downwind-type wind power generation equipment that prevents damage to the equipment (long life) and improves the capacity utilization rate of the wind power generation equipment.

[0007] An object of the present invention is to provide a wind turbine generator and a control method for a wind turbine generator that can ensure wind direction tracking and improve facility utilization rate, while preventing excessive loads and stresses from being placed on each device and causing damage to the devices, even when subjected to strong winds during yaw control. [Means for solving the problem]

[0008] The wind turbine generator of the present invention is a downwind type wind turbine generator that generates power by arranging the rotor downwind of the nacelle, comprising a rotor, a nacelle that supports the rotor, a tower that supports the nacelle so that it can yaw, a drive device that causes the nacelle to yaw, a braking device that brakes the yaw rotation of the nacelle, a wind vane and anemometer, and a control device that controls the drive device and the braking device based on the wind conditions measured by the anemometer, and is characterized in that when the wind conditions satisfy predetermined conditions, the control device releases the braking device to enter a free yaw state while continuing to generate power, and when the yaw rotation speed in the free yaw state remains smaller than a first threshold for a predetermined period of time, the control device starts the drive device.

[0009] Alternatively, the control method for a wind turbine generator of the present invention is a control method for a wind turbine generator comprising a rotor, a nacelle supporting the rotor, a tower supporting the nacelle so that it can yaw, a drive device for yaw rotating the nacelle, a braking device for braking the yaw rotation of the nacelle, and an anemometer, wherein when the wind conditions measured by the anemometer satisfy predetermined conditions, the braking device is released while continuing power generation to enter a free yaw state, and when the yaw rotation speed in the free yaw state remains smaller than a first threshold value for a predetermined period of time, the drive device is started. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a wind turbine generator and a control method for a wind turbine generator that can ensure wind direction tracking and improve facility utilization rate, while preventing excessive loads and stresses from being placed on each device and causing damage to the devices, even when subjected to strong winds during yaw control. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram showing an overall outline of a wind turbine generator according to an embodiment of the present invention; [Figure 2] FIG. 1 is a top view of a wind turbine generator according to an embodiment of the present invention. [Figure 3] FIG. 2 is a block diagram of a control device for a wind turbine generator according to the present embodiment. [Figure 4] FIG. 1 is a flowchart showing the yaw control operation of a general wind turbine generator. [Figure 5] FIG. 4 is a flowchart showing the yaw control operation of the wind turbine generator of the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] A wind turbine generator according to an embodiment of the present invention will be described in detail with reference to the drawings. In the drawings used in this specification, the same or corresponding components are designated by the same reference numerals, and repeated description of these components may be omitted. [Example]

[0013] Fig. 1 is a diagram showing an overall overview of a wind turbine generator according to this embodiment. As shown in Fig. 1, the wind turbine generator 1 is a downwind type, and generates electricity by rotating blades 2 due to wind blowing from left to right in the figure. It is equipped with a rotor 4 consisting of a plurality of blades 2 and a hub 3 to which the blades 2 are connected. Note that there may be only one blade 2. The rotor 4 is connected to a nacelle 6 via a rotating shaft (not shown), and the position of the blades 2 can be changed by rotating the rotor 4.

[0014] Furthermore, each blade 2 can be rotated around its vertical axis by a blade rotation mechanism 5 to change its angle (pitch angle). A nacelle 6 rotatably supports the rotor 4. The nacelle 6 is equipped with a generator 7, and when the blades 2 receive wind, the rotor 4 rotates, and this rotational force rotates the generator 7 to generate electricity, and a power converter 8 adjusts the rotation speed of the rotor 4 and the power of the wind turbine generator 1. In this embodiment, the nacelle 6 is installed on a tower 9, and can yaw around the vertical axis by a yaw rotation mechanism 10 (also called a yaw adjustment device).

[0015] The control device 20 controls the generator 7, blade rotation mechanism 5, and yaw rotation mechanism 10 based on the wind direction θw and wind speed Vw detected by the wind direction and speed sensor 11, which detects wind direction and speed. In this embodiment, the wind direction and speed sensor 11 is assumed to be a low-cost, common sensor with an arrow-type wind vane and a cup-type anemometer, but it may also be a Lidar such as a Doppler Lidar, an ultrasonic anemometer, or the like. The wind direction and speed sensor 11 may be attached to the wind power generation device, such as the nacelle 6 or tower, or may be attached to a mast or other structure separate from the wind power generation device.

[0016] The yaw rotation mechanism 10 is composed of a yaw bearing, yaw gear (gear for yaw rotation), drive unit (yaw motor), braking unit (a yaw brake such as an electromagnetic brake installed around the motor shaft of the yaw motor or a hydraulic brake installed around the yaw rotation shaft), etc. It is configured to be able to brake yaw rotation by controlling the regeneration of the yaw motor and the electromagnetic and hydraulic brakes. It is equipped with, in appropriate positions, a pitch actuator that can change the angle of the blades 2 relative to the hub 3, a power converter that controls the active power and reactive power output by the generator 7, and sensors that detect electrical or mechanical signals. The wind turbine generator shown in FIG. 1 is a downwind type that generates electricity using wind blowing from the nacelle 6 toward the blades 2.

[0017] Fig. 2 is a top view (plan view) of the wind turbine generator according to this embodiment, which illustrates the relationship between the wind direction relative to a predetermined reference direction defined as θw, the direction of the rotor rotation axis relative to the predetermined reference direction defined as θr, and the yaw deviation angle, which is the deviation angle from the wind direction θw to the rotor axis angle θr, defined as Δθ.

[0018] Here, the "predetermined reference direction" refers to, for example, a reference direction with north as 0°. The reference direction is not limited to north and may be set arbitrarily. The wind direction θw may be a value acquired at each measurement cycle, an average direction over a predetermined period, a direction filtered through a filter that passes only a predetermined frequency range, or a direction calculated based on the surrounding wind distribution. The rotor shaft angle θr may be the direction of the rotor rotation shaft, the direction of the nacelle 6, or a value measured by an encoder of the yaw rotation unit. The yaw rotation mechanism 10 is controlled by the control device 20 so that the yaw deviation angle Δθ is reduced.

[0019] Figure 3 is a block diagram of the control device for the wind turbine generator of this embodiment. That is, it is a block diagram showing the functions of the yaw control unit 100 that constitutes the control device 20 shown in Figure 1. As shown in Figure 3, the yaw control unit 100 is made up of a yaw deviation angle calculation unit 101 that calculates the yaw deviation angle Δθ, and a yaw control command unit 102 that determines a yaw control command that controls the start / drive / stop of yaw rotation based on the yaw deviation angle Δθ.

[0020] The yaw deviation angle calculation unit 101 determines the yaw deviation angle Δθ based on the rotor shaft angle θr and the wind direction θw. As shown in FIG. 2, this yaw deviation angle Δθ is the difference between the wind direction θw and the rotor shaft angle θr, and indicates how far the rotor shaft deviates from the wind direction. Here, the wind direction θw is not limited to a value detected by the wind direction and wind speed sensor 11 installed in the nacelle, but may use a value installed on the ground or elsewhere. Furthermore, the yaw deviation angle calculation unit 101 may use a filter, such as a low-pass filter, that passes only a predetermined frequency range of the yaw deviation angle Δθ, or a statistical value, such as a moving average, that uses the average value of values ​​over a predetermined period of time immediately preceding the calculation. Alternatively, a Fourier transform may be performed.

[0021] The yaw control command unit 102 controls the yaw rotation mechanism 10 based on wind conditions (wind speed and wind direction). For example, when the yaw deviation angle Δθ becomes equal to or greater than a predetermined threshold (an example of a predetermined condition), it turns on the yaw rotation command and starts yaw control operation. Once yaw control operation starts, the yaw control command unit 102 sets a target angle θp for the rotor shaft angle θr so as to reduce the yaw deviation angle Δθ, and controls the yaw motor and yaw brake. For example, the target angle θp may be the average value of the wind direction θw over the previous predetermined period, or a statistical value using this average value. When the difference between the rotor shaft angle θr and the target angle θp falls below a predetermined threshold as a result of control of the yaw motor and yaw brake, the yaw control command unit 102 terminates the yaw rotation command (turns off the yaw rotation command) and controls the yaw motor and yaw brake to stop yaw rotation. In this case, the predetermined threshold referenced when switching the yaw rotation command on and off may be set to a different value.

[0022] Furthermore, the yaw control command unit 102 according to this embodiment calculates the yaw angular velocity ω, which is the time rate of change of the rotor shaft angle θr, from the time-series data of the rotor shaft angle θr. The yaw control command unit 102 controls the yaw motor and the yaw brake based on the target angle θp and the yaw angular velocity ω. Hereinafter, the yaw angular velocity ω is defined as a positive value when the rotation direction approaches the target angle θp from the rotor shaft angle θr. The control of the yaw motor and the yaw brake by the yaw control command unit 102 will be described in detail later.

[0023] The yaw control operation of a typical wind turbine generator during power generation will be described with reference to Fig. 4. Fig. 4 is a flowchart showing the yaw control operation of a typical wind turbine generator.

[0024] As shown in Fig. 4, when the yaw rotation command is turned ON, the yaw control command unit controls the yaw brake to be turned OFF as shown in step S11 (step S11). After a predetermined time (e.g., 1.0 second) has elapsed since the yaw brake was turned OFF, the yaw control command unit 102 turns ON the yaw motor and controls the drive motor so that the wind direction and the rotor direction are aligned (step S12). The yaw control command unit 102 keeps the yaw motor ON until the yaw rotation command is turned OFF (step S14), and when the yaw rotation command is turned OFF (step S13), it turns OFF the yaw motor and turns ON the yaw brake (step S15), ending the yaw control operation.

[0025] However, if a wind turbine generator is hit by a strong wind while performing yaw control using the yaw motor, the wind load can cause excessive loads on the various components, potentially resulting in damage to the components. Therefore, the wind turbine generator of the first embodiment is configured to avoid yaw control using the yaw motor in situations where excessive loads are generated.

[0026] 5 is a diagram showing a flowchart of the yaw control operation of the wind turbine generator of this embodiment. Using FIG. 5, the yaw control operation during power generation of the wind turbine generator of this embodiment will be described.

[0027] As shown in Figure 5, when the yaw rotation command is turned ON, the yaw control command unit controls the yaw brake to be turned OFF (step S201). Unlike conventional yaw control, in the yaw control method of this embodiment, after the yaw braking means is turned OFF, the drive motor is not turned ON unless a predetermined condition (described later in the explanation of step S203) is met. This causes the nacelle to yaw rotate due to the force of the wind (free yaw state). While the yaw rotation command is ON (step S202, NO), the yaw control command unit controls the yaw motor and yaw brake based on the yaw angular velocity ω.

[0028] The yaw angular velocity ω is equal to a predetermined threshold ω L If ω<ω L ), the yaw control command unit proceeds to step S204. As the threshold value ωL, a value is used that determines that the yaw rotation of the nacelle has almost stopped, for example, 0.2 deg / s. If the yaw angular velocity ω is negative, that is, if the nacelle has started to rotate in the opposite direction to the target angle θp (step S204, Yes), the yaw control command unit proceeds to step S206 and turns on (starts) the yaw motor. After turning on the yaw motor, the yaw control command unit 102 returns to step S202. With this configuration, it is possible to improve the ability to follow the wind direction, for example, when a temporary gust of wind causes the nacelle to rotate in the opposite direction.

[0029] If the yaw angular velocity ω is equal to or greater than 0, that is, if the yaw rotation of the nacelle has stopped or is at an extremely low speed (step S204, No), the process proceeds to step S205. If the state in which the yaw rotation has stopped or is at an extremely low speed continues for a predetermined time (step S205, Yes), the yaw control command unit proceeds to step S206 and turns on the yaw motor. It is desirable to set the predetermined time period to be long enough for the wind to accelerate the nacelle in the yaw rotation direction. By turning on the yaw motor only after the predetermined time period has passed, it is possible to suppress yaw motor activation during the acceleration phase or in unstable wind conditions, and prevent excessive loads from being placed on each device.

[0030] After starting and turning on the yaw motor, the yaw control command unit returns to step S202. If the yaw rotation is stopped or remains at a very low speed for a predetermined period of time (step S205, No), the yaw control command unit returns to step S202 without operating the yaw motor. By configuring in this way, the yaw motor can be started to follow the wind direction even if, for example, the turning force caused by the wind is insufficient and the yaw rotation stops before the yaw deviation angle Δθ falls below a predetermined threshold.

[0031] Returning to the explanation of step S203, in step S203, the yaw angular velocity ω is equal to or greater than a predetermined threshold value ω H When the yaw angular velocity ω becomes larger than ω , the yaw control command unit 102 performs a regenerative operation of the yaw motor or activates the yaw brake, and the yaw angular velocity ω becomes larger than ω . H The yaw rotation is braked so that the yaw angular velocity ω falls below ω (step S207). H If the threshold value ω falls below ω (step S208, Yes), the yaw control command unit 102 turns off the yaw motor and the yaw brake to stop braking of the yaw rotation (step S209), and the process returns to step S202. H For example, the conventional set value of the yaw rotation speed (0.6 deg / s) or the allowable rotation speed (3.8 deg / s) of each device can be used. In step S203, if the yaw angular velocity ω falls within a predetermined range (ω L ≦ω≦ω H ), the yaw control command unit 102 returns to step S202.

[0032] When the yaw rotation command is turned OFF (step S202, Yes), the yaw control command unit 102 turns OFF the yaw motor and turns ON the yaw brake to stop the yaw rotation operation (step S210), and ends the yaw control operation.

[0033] According to the control operation disclosed in this embodiment, even if a strong wind is encountered during yaw control operation, by utilizing the free yaw state, it is possible to prevent the wind load from causing excessive load or stress on each piece of equipment, which could result in damage to the equipment. Furthermore, by performing yaw control operation according to the yaw angular velocity, it is possible to ensure wind direction tracking even when the wind direction is unstable, thereby improving the equipment utilization rate.

[0034] The present invention is not limited to the above-described embodiments, and various modifications are possible. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to embodiments including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment. It is also possible to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to delete part of the configuration of each embodiment, or to add or replace other configurations. [Explanation of symbols]

[0035] 1...wind power generation equipment, 2...Blade, 3...hub, 4...Rotor, 5...Blade rotation mechanism, 6... Nacelle, 7...Generator, 8...power converter, 9...Tower, 10...Yaw rotation mechanism, 11...wind direction and speed sensor, 20...control device, 100...Yaw control unit, 101...Yaw deviation angle calculation unit, 102...Yaw control command unit, θr: rotor shaft angle, θw...Wind direction, Δθ: yaw deviation angle, ω: Yaw angular velocity

Claims

1. a rotor, a nacelle supporting the rotor, a tower supporting the nacelle so that the nacelle can yaw rotate, a drive device for yaw rotating the nacelle, a braking device for braking the yaw rotation of the nacelle, a wind vane and anemometer, and a control device for controlling the drive device and the braking device based on wind conditions measured by the wind vane and anemometer, wherein the rotor is disposed downwind of the nacelle to generate power, The control device When the wind conditions satisfy predetermined conditions, the braking device is released to enter a free-yaw state while continuing to generate power, The wind turbine generator is characterized in that, when a state in which the yaw rotation speed in the free yaw state is smaller than a first threshold value continues for a predetermined time, the drive device is started.

2. The wind turbine generator according to claim 1, the control device sets a target angle for yaw rotation based on the wind conditions, and when the nacelle rotates in the direction opposite to the target angle in the free yaw state, starts the drive device before the predetermined time period continues.

3. The wind turbine generator according to claim 1, The wind turbine generator is characterized in that, when the yaw rotation speed in the free yaw state is greater than a second threshold value that is greater than the first threshold value, the control device controls the drive device and / or the braking device to reduce the yaw rotation speed.

4. A control method for a wind turbine generator including a rotor, a nacelle supporting the rotor, a tower supporting the nacelle so that the nacelle can yaw, a drive device for yaw rotating the nacelle, a braking device for braking the yaw rotation of the nacelle, and a wind vane and anemometer, When the wind conditions measured by the anemometer satisfy predetermined conditions, the braking device is released to enter a free-yaw state while continuing to generate power, A control method for a wind turbine generator, comprising starting the drive device when a state in which the yaw rotation speed in the free yaw state is smaller than a first threshold value continues for a predetermined time.

5. The method for controlling a wind turbine generator according to claim 4, a control method for a wind turbine generator, characterized in that a target angle for yaw rotation is set based on the wind conditions, and when the nacelle rotates in a direction opposite to the target angle in the free yaw state, the drive unit is started before the predetermined time period continues.

6. The method for controlling a wind turbine generator according to claim 4, A control method for a wind turbine generator, characterized in that when the yaw rotation speed in the free yaw state is greater than a second threshold value that is greater than the first threshold value, the drive device and / or the brake device are controlled to reduce the yaw rotation speed.

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