Wind power generation device

Abstract

This wind power generation device comprises: a rotor shaft body that is capable of rotating about a first rotation axis; a first power generator that converts rotational energy of the rotor shaft body into electric power; rotating bodies that are connected to the rotor shaft body and are capable of rotating about a second rotation axis that differs from the first rotation axis; blades that are fixed to the rotating bodies; and a second power generator that converts rotational energy of the rotating bodies into electric power.

Description

Wind power generation equipment

[0001] The present invention relates to a wind turbine generator. The present invention claims priority to Japanese Patent Application No. 2023-147737, filed on September 12, 2023, the contents of which are incorporated herein by reference.

[0002] Patent Document 1 discloses a wind turbine generator that includes a tower rotatably mounted around an inner cylinder, blades that rotate in response to wind, and a nacelle that is mounted on the tower and houses a generator that generates electricity through the rotation of the blades. In this wind turbine generator, the rotation of the tower is controlled based on the detection value of a wind vane mounted on the nacelle.

[0003] Japanese Patent Application Publication No. 2020-118076

[0004] In the case of the wind turbine generator, the rotation of the rotor shaft, which rotates due to the rotation of the blades when the wind blows directly at it, is increased by a speed increaser to generate electricity using a generator. However, this does not allow for a high degree of freedom in power generation control.

[0005] The present invention has been made to solve the above-mentioned problems, and has an object to provide a wind turbine generator that can increase the degree of freedom in power generation control.

[0006] To solve the above problems, one aspect of the present invention has the following configuration: (1) A wind turbine generator according to one aspect of the present invention includes a rotor shaft rotatable about a first rotation axis, a first generator that converts rotational energy of the rotor shaft into electric power, a rotating body connected to the rotor shaft and rotatable about a second rotation axis different from the first rotation axis, blades fixed to the rotating body, and a second generator that converts rotational energy of the rotating body into electric power.

[0007] With this configuration, electricity can be generated not only by the rotation of the rotor shaft (rotation around the first rotation axis) but also by the rotation of the blades themselves (rotation around the second rotation axis), thereby increasing the freedom of power generation control.

[0008] (2) The wind turbine generator described in (1) above may further include a tower and a nacelle rotatably supported on the tower, and the first generator may be housed in the nacelle.

[0009] (3) The wind power generation device described in (1) or (2) above may further include a first power generation control unit that controls the first generator and a second power generation control unit that controls the second generator.

[0010] (4) The wind power generation device described in (3) above may further include a rotational speed acquisition unit that detects the actual rotational speed of the rotor shaft or the first generator, and a wind condition acquisition unit that acquires wind condition information including the current wind speed, and the first power generation control unit may control the first generator based on a comparison result between the actual rotational speed and the rated rotational speed, and the second power generation control unit may control the second generator based on the wind condition information.

[0011] (5) In the wind power generation device described in (4) above, the second power generation control unit may control the second generator to slow down the rotation of the rotating body when the current wind speed is equal to or greater than a threshold value.

[0012] (6) The wind power generation device described in any of (3) to (5) above may further include a position detection unit that detects the tip position of the blade, and the second power generation control unit may control the second generator to slow down the rotation of the rotating body when the detected tip position of the blade is equal to or greater than a height threshold.

[0013] (7) The wind power generation device described in any of (3) to (6) above may further include a wind condition acquisition unit that acquires wind condition information including the current wind speed, and the second power generation control unit may control the second generator to slow down the rotation of the rotating body when the actual rotation speed of the first generator is faster than the current wind speed.

[0014] (8) In the wind power generation device described in any one of (3) to (7) above, the second power generation control unit may control the second generator to change the speed of rotation of the rotating bodies on the left and right of the orbital position.

[0015] According to the present invention, the degree of freedom in power generation control can be increased.

[0016] 8 is a perspective view of a wind turbine generator according to a first embodiment; FIG. 9 is a diagram illustrating an example of the functional configuration of the wind turbine generator according to the first embodiment; FIG. 10 is a diagram illustrating the rotation direction of each part of the wind turbine generator according to the first embodiment; FIG. 11 is a perspective view of a blade according to the first embodiment, viewed from one side; FIG. 12 is a perspective view of a blade according to the first embodiment, viewed from the other side; FIG. 13 is a perspective view of an assembly according to the first embodiment; FIG. 14 is a diagram illustrating a flow velocity distribution in the case of eight blades; FIG. 15 is a diagram illustrating propulsion in the case of eight blades; FIG. 16 is a diagram illustrating propulsion in the case of eight blades, following FIG. 8; FIG. 17 is a diagram illustrating an example of braking force control according to the rotation mode of the wind turbine generator according to the first embodiment; FIG. 18 is an explanatory diagram of relative wind speed and the like in a headwind; FIG. 19 is a diagram illustrating an example of wind direction component force and orthogonal component in the case of eight blades; FIG. 19 is a diagram illustrating an example of the relationship between relative wind direction and optimal lift coefficient; FIG. 19 is a diagram illustrating an example of the relationship between rotation speed, propulsion force, and generated energy; FIG. 19 is a diagram illustrating an example of the relationship between lift constant and lift-drag ratio; FIG. 19 is a flowchart illustrating a first example of control of a second generator; FIG. 19 is a flowchart illustrating a second example of control of a second generator; FIG. 19 is a flowchart illustrating a third example of control of a second generator; 10 is a perspective view of a second position of a plurality of blades in a wind propulsion device of a second embodiment, as seen from one side; FIG. 11 is an explanatory diagram of the operation of the wind propulsion device of the second embodiment; FIG. 12 is a diagram showing a modified example of a shape in which a plurality of blades are twisted; FIG. 13 is a side view including a longitudinal section of a blade of a third embodiment; FIG. 14 is a diagram including a transverse section of a blade of a third embodiment; FIG. 15 is a diagram showing a blade of a third embodiment, as seen from one side of a second rotation shaft; FIG. 16 is a diagram showing an example of the operation of a blade of a third embodiment; FIG. 17 is a diagram showing another example of the operation of a blade of a third embodiment; FIG. 18 is a diagram showing a modified example of a wind turbine generator;

[0017] Hereinafter, a wind turbine generator according to an embodiment of the present invention will be described with reference to the drawings. In the following description, expressions indicating relative or absolute arrangements, such as "parallel," "orthogonal," "center," and "coaxial," do not only mean the exact arrangement, but also include relative displacements with tolerances or angles or distances that provide the same functionality. In the drawings used in the following description, the scale of each component has been appropriately changed to make each component recognizable.

[0018] <Wind Turbine Generator> FIG. 1 is a perspective view of a wind turbine generator 1 according to a first embodiment. FIG. 2 is a diagram illustrating an example of the functional configuration of the wind turbine generator 1 according to the first embodiment. FIG. 3 is a diagram illustrating the rotational direction of each component of the wind turbine generator 1 according to the first embodiment. Referring to FIGS. 1 to 3 , the wind turbine generator 1 includes a rotor shaft 70 rotatable about a first rotation axis RC1, a first generator 71 that converts rotational energy of the rotor shaft 70 into electric power, rotors 20A-20D connected to the rotor shaft 70 and rotatable about a second rotation axis RC2 different from the first rotation axis RC1, blades 10A-10H fixed to the rotors 20A-20D, and a second generator 72 that converts rotational energy of the rotors 20A-20D into electric power. The wind turbine generator 1 functions as a horizontal axis wind turbine, with the first rotation axis RC1 being a horizontal axis extending horizontally. The second rotation axis RC2 corresponds to an axis along the longitudinal direction of the blades 82A to 82E. In the example shown in the figure, the second rotation axis RC2 of the blade 82A is shown.

[0019] The wind turbine generator 1 further includes a tower 80 and a nacelle 81 that is rotatably supported on the tower 80. The first generator 71 is housed in the nacelle 81.

[0020] The nacelle 81 is attached to the upper end of the tower 80. The nacelle 81 is capable of rotating (yaw rotation) around the tower 80. For example, a yaw drive device (not shown) capable of yaw rotating the nacelle 81 is provided at the upper end of the tower 80.

[0021] The rotors 20A to 20D and the wings 10A to 10H make up the blades 82A to 82E. The blades 82A to 82E are connected to the nacelle 81 via a hub 83. The blades 82A to 82E are arranged radially around the hub 83. The roots of the blades 82A to 82E are attached to the hub 83.

[0022] At least one blade 82A-82E is provided. In the example shown in the figure, five blades 82A-82E (an example of a plurality) are provided at equal intervals in the circumferential direction around the first rotation axis RC1. A second generator 72 is provided for each of the plurality of blades 82A-82E. Note that the configuration (number, arrangement, etc.) of the blades 82A-82E is not limited to the above and can be changed according to design specifications.

[0023] For example, a speed increaser 84 is provided inside the nacelle 81. The rotation of the rotor shaft 70 connected to the hub 83 is increased in speed by the speed increaser 84. The increased rotational force is transmitted to the first generator 71, thereby generating electricity.

[0024] Three rotations occur in the wind turbine generator 1. The first rotation is a yaw rotation (rotation in the direction of arrow R1 shown in FIG. 3) in which the nacelle 81 rotates around the tower 80. The second rotation is a horizontal axis rotation (rotation in the direction of arrow R2 shown in FIG. 3) in which the hub 83 to which the blades 82A to 82E are attached rotates around a first rotation axis RC1. The third rotation is a pitch rotation (rotation in the direction of arrow R3 shown in FIG. 3) in which the blades 82A to 82E rotate around a second rotation axis RC2. The horizontal axis rotation of the hub 83 causes the blades 82A to 82E to revolve around the first rotation axis RC1.

[0025] The wind turbine generator 1 further includes a first power generation control unit 73 that controls the first generator 71 and a second power generation control unit 74 that controls the second generator 72 .

[0026] For example, the first power generation control unit 73 and the second power generation control unit 74 include a processor such as a CPU (Central Processing Unit) and a memory connected by a bus. The processor reads a power generation control program stored in a storage unit (not shown) and stores the read power generation control program in the memory. The processor executes the power generation control program stored in the memory.

[0027] The wind turbine generator 1 further includes a rotational speed acquisition unit 75 that detects the actual rotational speed of the rotor shaft 70 or the first generator 71, and a wind condition acquisition unit 7 that acquires wind condition information including the current wind speed. The first power generation control unit 73 controls the first generator 71 based on the comparison result between the actual rotational speed and the rated rotational speed. The second power generation control unit 74 controls the second generator 72 based on the wind condition information.

[0028] For example, the rotational speed acquisition unit 75 may include a sensor that detects the rotational speed (number of revolutions) of the rotor shaft 70 or the first generator 71. The rotational speed acquisition unit 75 may also include a proximity sensor. The proximity sensor may be configured to output an ON signal when metal is located within a certain distance and to output an OFF signal when metal is not located within the certain distance. In this case, the proximity sensor outputs an ON signal when, for example, a convex portion of the irregularities on the surface of the rotor shaft 70 is located within the detection range, and outputs an OFF signal when a concave portion is located within the detection range. The rotational speed acquisition unit 75 may acquire the rotational speed of the rotor shaft 70 based on such a change in the output of the proximity sensor and previously obtained information indicating the spacing between the irregularities on the rotor shaft 70.

[0029] The rotation speed acquisition unit 75 is not limited to a proximity sensor and may include other types of devices. For example, the rotation speed acquisition unit 75 may include an encoder.

[0030] The wind condition acquisition unit 7 acquires wind condition information including wind direction in the installation area of ​​the wind turbine generator 1. The wind condition acquisition unit 7 acquires wind condition information including wind direction and wind speed. For example, the wind condition acquisition unit 7 is provided on the nacelle 81. The wind condition acquisition unit 7 is configured to include a wind direction and anemometer.

[0031] The wind turbine generator 1 further includes a position detector 76 that detects the tip positions of the blades 82A to 82E (an example of the tip positions of the blades).

[0032] For example, the position detection unit 76 may detect the rotation angle around the first rotation axis RC1 when the blades 82A to 82E rotate due to the wind. For example, if the position detection unit 76 detects values ​​of 0 degrees, 90 degrees, 180 degrees, and 270 degrees as the rotation angle, the position detection unit 76 detects position information of up, right, down, and left as the tip positions of the blades 82A to 82E, respectively.

[0033] <Blades> Fig. 4 is a perspective view of blades 82A to 82E of the first embodiment as seen from one side (the tip side of one blade in the illustrated example). Fig. 5 is a perspective view of blades 82A to 82E of the first embodiment as seen from the other side (the root side of one blade in the illustrated example). Fig. 6 is a perspective view of assembly 4A of the first embodiment.

[0034] 4 to 6, blades 82A to 82E are configured by stacking multiple assemblies 4A to 4C. The multiple assemblies 4A to 4C are provided along the direction of second rotation axis RC2. If the number of assemblies 4A to 4C is N and M is a natural number, the multiple assemblies 4A to 4C are arranged with a staggered arrangement of 180×M / N degrees from one another.

[0035] In the illustrated example, the three assemblies 4A to 4C are disposed at 60-degree offsets from one another. In the illustrated example, the second assembly 4B is disposed at a 60-degree offset (60 degrees clockwise as viewed from one side of the second rotation axis RC2) with respect to the first assembly 4A constituting the three assemblies 4A to 4C, and the third assembly 4C is disposed at a 120-degree offset (120 degrees clockwise as viewed from one side of the second rotation axis RC2). Note that the configuration (number, arrangement, etc.) of the multiple assemblies 4A to 4C is not limited to the above and can be changed according to design specifications.

[0036] In this embodiment, the first assembly 4A, the second assembly 4B, and the third assembly 4C that make up the three assemblies 4A to 4C have their blades 10A to 10H connected to one another via rotating plates 20A to 20D. In this embodiment, the rotating plates 20A to 20D are configured to include a base plate 20A, a first intermediate plate 20B, a second intermediate plate 20C, and a tip plate 20D.

[0037] The plurality of blades 10A-10H constituting the first assembly 4A have their bases fixed to the base plate 20A and their tips fixed to the first intermediate plate 20B. The plurality of blades 10A-10H constituting the second assembly 4B have their bases fixed to the first intermediate plate 20B and their tips fixed to the second intermediate plate 20C. The plurality of blades 10A-10H constituting the third assembly 4C have their bases fixed to the second intermediate plate 20C and their tips fixed to the tip plate 20D.

[0038] With this configuration, the assemblies 4A to 4C are strong because the load is borne by the entire cylinder, not by the support pillars. Furthermore, the absence of a central support pillar reduces wind resistance. Furthermore, when stacking multiple assemblies 4A to 4C, they can be easily stacked by simply fastening one assembly (e.g., the first assembly 4A) to the other assembly (e.g., the second assembly 4B) with fastening members such as bolts. Additionally, because the connecting portions of the multiple assemblies 4A to 4C do not have moving parts such as motors, they can be easily assembled on-site.

[0039] Next, the configuration of the assemblies 4A to 4C will be described using the first assembly 4A as an example. The other assemblies 4B and 4C have the same configuration as the first assembly 4A, and therefore detailed description thereof will be omitted. Also referring to FIG. 6 , the first assembly 4A comprises rotors 20A and 20B that can rotate about a second rotation axis RC2 (shown as a dashed line in the figure) and a plurality of plate-shaped blades 10A to 10H that are fixed to the rotors 20A and 20B. The blades 10A to 10H are arranged so that imaginary lines connecting both ends of each blade are parallel. The blades 10A to 10H are arranged so that both ends are located on an imaginary circle centered on the rotation axis. The longest of the blades 10A to 10H (the innermost blade) is arranged so that the length of the imaginary line (the length from one end of the blade to the other, the so-called chord length) is at least half the diameter of the imaginary circle centered on the rotation axis. The chord length of the outermost blade among the plurality of blades 10A to 10H may be less than half the diameter of an imaginary circle centered on the rotation axis. Note that the chord lengths of the plurality of blades are not limited to the above and can be changed according to the design specifications.

[0040] In the example shown in the figure, the imaginary circle centered on the rotation axis is a perfect circle when viewed along the second rotation axis RC2. Note that the shape of the imaginary circle when viewed along the second rotation axis RC2 is not limited to the above, and may be an ellipse, an oval, a rectangle, or a closed loop formed by connecting curves.

[0041] The rotating bodies 20A, 20B are plate-shaped rotating plates 20A, 20B. The plurality of blades 10A to 10H are fixed to one surface of the rotating plates 20A, 20B, respectively. In the example shown in the figure, the rotating plates 20A, 20B include a base plate 20A to which the bases of the plurality of blades 10A to 10H are fixed, and a first intermediate plate 20B (an example of a tip plate) to which the tips of the plurality of blades 10A to 10H are fixed. For example, the base plate 20A is rotatably connected to a support plate 25 on a hub 83 via a bearing (not shown).

[0042] The rotating plates 20A, 20B include an annular frame 21 and a plurality of beams 22, each of which is connected at both ends to the inner periphery of the frame 21 and is arranged parallel to one another. In the illustrated example, three beams 22 are arranged at equal intervals and each of which is connected at both ends to the inner periphery of the frame 21. Note that the configuration (number, arrangement, etc.) of the beams 22 is not limited to the above and can be changed according to design specifications. For example, the configuration (shape, etc.) of the rotating bodies 20A, 20B may be a solid disk (an example of a rotating plate) or a hollow disk. The configuration of the rotating bodies 20A, 20B is not limited to the above and can be changed according to design specifications.

[0043] In this embodiment, the blades 82A to 82E are configured by stacking three assemblies, but this is not limited to the above, and the number of assemblies configuring the blades 82A to 82E can be changed according to design specifications. For example, the blades 82A to 82E may be configured by a single assembly. For example, if there are multiple assemblies A and B, the rotating bodies 20A and 20B of assembly A and assembly B may be common. For example, the installation manner of the rotating bodies 20A and 20B relative to the multiple assemblies can be changed according to design specifications. Furthermore, assemblies A and B may have the same shape, or the rotating bodies 20A and 20B may be bolted or welded.

[0044] The multiple blades 10A-10H extend in a direction along the second rotation axis RC2. When viewed from a direction along the second rotation axis RC2, the multiple blades 10A-10H are provided so as to be line-symmetrical with respect to a center line that passes through the rotation center of the second rotation axis RC2 and is parallel to an imaginary line. When viewed from a direction along the second rotation axis RC2, the multiple blades 10A-10H are provided so as to be line-symmetrical with respect to a center line that passes through the rotation center of the second rotation axis RC2 and is perpendicular to the imaginary line.

[0045] In the illustrated example, each of the eight blades 10A to 10H extends in a direction along the second rotation axis RC2 so as to intersect with the three beam portions 22 of the rotating plates 20A and 20B. In the illustrated example, of the eight blades 10A to 10H, the four blades 10A to 10D on one side of the rotation center and the four blades 10E to 10H on the other side are provided at equal intervals. Note that the configuration (number, arrangement, etc.) of the blades 10A to 10H is not limited to the above and can be changed according to design specifications.

[0046] <Propulsion in the Case of Eight Blades> Figure 7 is a diagram showing the flow velocity distribution in the case of eight blades. Figure 8 is a diagram explaining propulsion in the case of eight blades. Figure 9 is a diagram following Figure 8 and explaining propulsion in the case of eight blades. In the example shown in the figure, a support is shown at the center of rotation of the second rotation axis RC2, but the support may be omitted. In the example shown in the figure, the blades 82A to 82E are positioned horizontally (for example, when the tip positions of the blades 82A to 82E are on the right or left). In the example shown in the figure, the propulsion force corresponds to a force in the direction in which the blades 82A to 82E revolve.

[0047] Referring also to Figures 7 to 9, the eight-blade blades rotate regardless of wind direction. Since the part of the eight-blade blade above the center of rotation is aligned with the direction of rotation, the wind on the upper side accelerates and the wind on the lower side decelerates. Then, according to Bernoulli's theorem, the pressure on the upper side decreases and the pressure on the lower side increases. This pressure difference generates a thrust force perpendicular to the wind direction. This thrust force is called the Magnus force. Note that if the wind direction is reversed, the blades will rotate in the opposite direction. Originally, the Magnus force is a force generated by the rotation of a cylinder or sphere, but the thrust force generated by parallel blades is called the Magnus force because the force generation mechanism is similar. Furthermore, the Magnus force is also called lift because it acts perpendicular to the wind.

[0048] In this embodiment, the eight blades are arranged so that both ends are located on an imaginary circle centered on the second rotation axis RC2, and the imaginary lines connecting both ends of each blade are parallel. This allows the generated thrust to be greater than when there are seven or fewer blades. Note that although it is affected by the Reynolds number, i.e., size and wind speed, the thrust generally tends to increase as the number of blades increases. For example, 18 blades may also be used.

[0049] <Braking Force Control by Rotation Mode of Wind Turbine Generator> Figure 10 is a diagram showing an example of braking force control by rotation mode of the wind turbine generator 1 of the first embodiment. Referring also to Figure 10, braking force control by rotation mode of the wind turbine generator 1 can be divided into "driving" and "free" modes. "Free" means propulsion by wind power alone, without using other power sources such as a motor. There is also an intermediate rotation mode between "low-speed driving" and "free" that reduces the proportion of power from the motor, etc., and in that case, an intermediate value between the two is optimal. For example, the generator (motor) may be controlled by switching between modes, such as braking, driving, or free, depending on the wind speed and wind direction.

[0050] FIG. 11 is an explanatory diagram of the relative wind speed when there is a headwind. In FIG. 11, θ represents the wind direction taking into account the relative wind speed associated with the revolution speed (the speed at which the blades 82A to 82E revolve). Also referring to FIG. 11, when the blades are rotated by the force of the wind, if the headwind becomes relatively stronger as the blades 82A to 82E revolve, the blades will rotate at a higher speed. As a result, the propulsive force in the revolution direction increases due to the Magnus effect.

[0051] In the wind power generation device 1 of this embodiment, the blades are rotated by the force of the wind, so when the headwind becomes relatively stronger as the blades 82A to 82E revolve, the blades rotate at a higher speed, and the Magnus effect allows propulsion in the direction of revolution to be obtained even in headwinds.

[0052] Fig. 12 is a diagram showing an example of wind component forces and orthogonal components in the case of an eight-blade aircraft. Also referring to Fig. 12, the wind component forces and orthogonal components are calculated, for example, by fluid analysis (two-dimensional analysis). For example, in the case of the eight-blade aircraft shown in Fig. 12, the drag force T = 39 kN, the lift force F = 354 kN, and the lift-to-drag ratio F / T = 9 is obtained.

[0053] For example, in the case of a wind blowing directly from the side (say, a wind speed of 10 m / s), if the speed is multiplied by the lift-to-drag ratio, the propulsive force will be zero. If the resistance is zero and the aircraft is left free, the speed will be this (say, 90 m / s). Note that the propulsive force due to wind power is at its maximum at 2 / 3 of the above speed (say, 60 m / s).

[0054] The above is for a two-dimensional analysis, but in three dimensions the aspect ratio has an effect. In general, induced drag occurs with lift, and when the lift is large and the aspect ratio is small, this has a significant effect.

[0055] The relational expressions for the three-dimensional case are shown in the following equations (1) to (5). Ｄ is the drag constant, C Ｄ０ is the drag constant in two-dimensional analysis, C Ｌ is the lift constant, π is the ratio of the circumference of the aircraft's circumference to its circumference, e is the Oswald constant, AR is the aspect ratio, θ is the wind direction (taking into account the relative wind speed associated with the orbital speed), V is the wind speed, ρ is the density, and S is the wing area.

[0056]

[0057] From the above formula (1), when the airfoil is applied to the high-speed blades 82A to 82E, for example, it is preferable that the airfoil has an elongated shape.

[0058]

[0059] The thrust in the revolution direction can be calculated by maximizing the value of the above formula (2). When there is a tailwind, the lift constant C Ｌ However, because of the orbital speed, in most cases there is a headwind (θ is an obtuse angle), and in that case the optimal C Ｌ When the above formula (2) is differentiated to find the extreme value, the following formula (3) is obtained.

[0060]

[0061] For example, to achieve maximum speed by freeing the aircraft, the lift-to-drag ratio should be maximized. Differentiating the following equation (4), the lift-to-drag ratio becomes maximum when the following equation (5) is obtained, and the aircraft can achieve maximum speed.

[0062]

[0063]

[0064] <Drive> Fig. 13 is a diagram showing an example of the relationship between the relative wind direction and the optimal lift coefficient. Fig. 14 is a diagram showing an example of the relationship between the rotation speed, thrust, and power generation energy. Referring also to Figs. 10 to 14, in the case of drive, for example, the relative wind direction is first calculated. For example, the relative wind direction is calculated based on the acquired revolution speeds of the blades 82A to 82E and wind condition information. The relative wind direction may also be acquired by the wind condition acquisition unit 7.

[0065] Next, the optimum lift coefficient is calculated based on the calculated relative wind direction, for example, based on equation (3) or the graph shown in Figure 13 (for example, data obtained in advance).

[0066] Next, the blade rotation speed is calculated based on the calculated optimum lift coefficient. For example, the blade rotation speed is calculated based on the graph shown in Fig. 14 (for example, data obtained in advance).

[0067] Next, the braking force is controlled based on the calculated blade rotation speed. For example, the braking force may be controlled so that a predetermined propulsion force and power generation energy are obtained while maintaining a constant blade rotation speed. For example, when there is a headwind, the rotation speed may be reduced by applying the brakes (generating power), and the lift coefficient may be adjusted.

[0068] <Free> Fig. 15 is a diagram showing an example of the relationship between the lift constant and the lift-to-drag ratio. In Fig. 15, the optimal lift coefficient value is obtained when the aspect ratio AR = 2.5. Referring to Figs. 10 to 15 together, for example, in the free case, the optimal lift coefficient is first calculated. For example, the optimal lift coefficient is calculated based on equation (5) or the graph shown in Fig. 15 (for example, data acquired in advance).

[0069] Next, the blade rotation speed is calculated based on the calculated optimal lift coefficient, and the braking force is controlled. Note that the blade rotation speed calculation and braking force control in the free state may be performed in the same manner as in the drive described above.

[0070] <Example of Control of Second Generator> Fig. 16 is a flowchart showing a first example of control of the second generator 72. Referring also to Fig. 16, the second power generation control unit 74 controls the second generator 72 to decelerate the rotation of the rotating bodies 20A to 20D when the current wind speed is equal to or higher than a threshold value.

[0071] Specifically, first, the wind condition acquisition unit 7 acquires wind condition information including the current wind speed (step S11 shown in FIG. 16 ). The acquired data on the wind condition information including the current wind speed is sent to the second power generation control unit 74. After step S11, the process proceeds to step S12.

[0072] In step S12, the second power generation control unit 74 determines whether the current wind speed is equal to or greater than the threshold. If NO in step S12 (the current wind speed is less than the threshold), the process returns to step S11. If YES in step S12 (the current wind speed is equal to or greater than the threshold), the process proceeds to step S13.

[0073] In step S13, the second power generation control unit 74 controls the second power generator 72 to decelerate the rotation of the rotating bodies 20A to 20D. This completes the flow of the first example of the control of the second power generator 72.

[0074] Fig. 17 is a flowchart showing a second example of control of the second generator 72. Referring also to Fig. 17, the second power generation control unit 74 controls the second generator 72 to decelerate the rotation of the rotors 20A to 20D when the detected tip positions of the blades 82A to 82E (an example of the tip positions of the blades) are equal to or greater than the height threshold.

[0075] Specifically, first, the position detection unit 76 detects the tip positions of the blades 82A to 82E. Data relating to the detected tip positions of the blades 82A to 82E is transmitted to the second power generation control unit 74. After step S21, the process proceeds to step S22.

[0076] In step S22, the second power generation control unit 74 determines whether the detected tip positions of the blades 82A to 82E are equal to or greater than the height threshold. If NO in step S22 (the tip positions of the blades 82A to 82E are less than the height threshold), the process returns to step S21. If YES in step S22 (the tip positions of the blades 82A to 82E are equal to or greater than the height threshold), the process proceeds to step S23.

[0077] In step S23, the second power generation control unit 74 controls the second power generator 72 to decelerate the rotation of the rotors 20A to 20D. This completes the second example of the flow of control of the second power generator 72.

[0078] Fig. 18 is a flowchart showing a third example of control of the second generator 72. Referring also to Fig. 18, when the actual rotation speed of the first generator 71 is faster than the current wind speed, the second power generation control unit 74 controls the second generator 72 to decelerate the rotation of the rotating bodies 20A to 20D.

[0079] Specifically, first, the wind condition acquisition unit 7 acquires wind condition information including the current wind speed (step S31 shown in FIG. 18 ). The acquired data on the wind condition information including the current wind speed is transmitted to the second power generation control unit 74. After step S31, the process proceeds to step S32.

[0080] In step S32, the second power generation control unit 74 determines whether the actual rotation speed of the first generator 71 is faster than the current wind speed. If the answer is NO in step S32 (the actual rotation speed of the first generator 71 is equal to or lower than the current wind speed), the process returns to step S31. If the answer is YES in step S32 (the actual rotation speed of the first generator 71 is faster than the current wind speed), the process proceeds to step S33.

[0081] In step S33, the second power generation control unit 74 controls the second power generator 72 to decelerate the rotation of the rotating bodies 20A to 20D. This completes the flow of the third example of the control of the second power generator 72.

[0082] Note that windmill sail windmills have no concept of a tailwind; wind coming from the front is a crosswind for windmill sailboats, while the relative wind caused by rotation is a headwind for windmill sailboats. Therefore, when the windmill is stopped, the wind direction is 90 degrees; as it rotates, it becomes an obtuse angle such as 120 degrees; and as the rotation speed increases, it approaches 180 degrees. This depends on whether the windmill is rotating at a constant speed or at a natural rotation speed. When the rotation speed is fixed, the relative wind direction θ is calculated based on the wind speed and the rotation speed, and the optimal lift coefficient is calculated using equation (3). When the windmill is rotating at a natural rotation speed, the optimal lift coefficient is calculated using equation (5). If the lift coefficient generated by the windmill sails at a natural rotation speed is smaller than the optimal lift coefficient calculated above, the windmill is allowed to rotate at a natural rotation speed. In some cases, the rotation motor may be driven to increase the rotation speed. If the lift coefficient generated by natural rotation is greater than the optimum lift coefficient, the rotation motor is braked to reduce the rotation speed, adjusting the lift coefficient to the optimum value. This increases the revolution torque and / or revolution speed, improving power generation efficiency.

[0083] As a fourth example of control of the second generator 72, the second power generation control unit 74 controls the second generator 72 to change the rotation speed of the rotating bodies 20A to 20D on the left and right of the revolution position. For example, the second power generation control unit 74 controls the second generator 72 to slow down the rotation of the rotating bodies 20A to 20D on the left side of the revolution position when viewed from upwind, and to speed up the rotation of the rotating bodies 20A to 20D on the right side.

[0084] <Action and effect> As described above, the wind turbine generator 1 according to this embodiment comprises the rotor shaft 70 rotatable about a first rotation axis RC1, a first generator 71 that converts the rotational energy of the rotor shaft 70 into electric power, rotating bodies 20A to 20D that are connected to the rotor shaft 70 and rotatable about a second rotation axis RC2 different from the first rotation axis RC1, blades 10A to 10H fixed to the rotating bodies 20A to 20D, and a second generator 72 that converts the rotational energy of the rotating bodies 20A to 20D into electric power.

[0085] With this configuration, electricity can be generated not only by the rotation of the rotor shaft 70 (rotation around the first rotation axis RC1) but also by the rotation of the blades 10A to 10H themselves (rotation around the second rotation axis RC2), thereby increasing the freedom of power generation control.

[0086] The wind turbine generator 1 according to this embodiment further includes a tower 80 and a nacelle 81 that is rotatably supported on the tower 80. The first generator 71 is housed in the nacelle 81. This configuration increases the degree of freedom in power generation control in the horizontal axis wind turbine.

[0087] The wind turbine generator 1 according to this embodiment further includes a first power generation control unit 73 that controls the first generator 71, and a second power generation control unit 74 that controls the second generator 72. With this configuration, it is possible to adjust the amount of power generated by the rotation of the rotor shaft 70, as well as the amount of power generated by the rotation of the blades 10A to 10H themselves.

[0088] The wind turbine generator 1 according to this embodiment further includes a rotational speed acquisition unit 75 that detects the actual rotational speed of the rotor shaft 70 or the first generator 71, and a wind condition acquisition unit 7 that acquires wind condition information including the current wind speed. The first power generation control unit 73 controls the first generator 71 based on the comparison result between the actual rotational speed and the rated rotational speed. The second power generation control unit 74 controls the second generator 72 based on the wind condition information. With this configuration, the amount of power generated by the wind turbine generator 1 can be adjusted by power generation amount control based on the comparison result between the actual rotational speed and the rated rotational speed, and power generation amount control based on the wind condition information.

[0089] In the wind turbine generator 1 according to this embodiment, the second power generation control unit 74 controls the second generator 72 to decelerate the rotation of the rotors 20A to 20D when the current wind speed is equal to or greater than a threshold value. With this configuration, the lift can be reduced by decelerating the rotation of the blades 10A to 10H themselves, which makes it difficult for the Magnus effect to work in strong winds and makes it difficult for the blades 10A to 10H to revolve, thereby reducing the force that the blades 10A to 10H receive.

[0090] The wind turbine generator 1 according to this embodiment further includes a position detection unit 76 that detects the tip positions of the blades 10A to 10H. The second power generation control unit 74 controls the second generator 72 to decelerate the rotation of the rotors 20A to 20D when the detected tip positions of the blades 10A to 10H are equal to or greater than the height threshold. With this configuration, by decelerating the rotation of the rotors 20A to 20D whose tip positions of the blades 10A to 10H are equal to or greater than the height threshold, the rotation of the rotors 20A to 20D whose tip positions are less than the height threshold relatively increases, thereby making it possible to uniformize the force acting in the height direction.

[0091] The wind turbine generator 1 according to this embodiment includes a wind condition acquisition unit 7 that acquires wind condition information, including the current wind speed. When the actual rotation speed of the first generator 71 is faster than the current wind speed, the second power generation control unit 74 controls the second generator 72 to decelerate the rotation of the rotors 20A to 20D. With this configuration, since drag (a force that impedes rotation) increases when the revolution rotation speed is fast, it is possible to brake the rotation and reduce the induced drag.

[0092] In the wind turbine generator 1 according to this embodiment, the second power generation control unit 74 controls the second generator 72 to change the rotation speed of the rotors 20A to 20D on the left and right of the orbital position. This configuration adjusts the balance of the force that the blades 10A to 10H receive in the downwind direction, thereby enabling the blades 10A to 10H to be yaw-driven. For example, if the rotation of the rotors 20A to 20D on the left side of the orbital position as viewed from upwind is slowed down and the rotation of the rotors 20A to 20D on the right side is increased, the right side will be pushed backward more strongly due to the Magnus effect on the orbital speed, and the blades 10A to 10H will be yaw-driven to the right.

[0093] Conventionally, there are Magnus wind turbines in which cylinders function as blades. However, conventional Magnus wind turbines require energy to rotate the cylinders on their axes, and part of the energy generated when the cylinders revolve is used for this purpose. In contrast, in the wind turbine generator 1 according to this embodiment, the blades 82A to 82E rotate on their axes using the force of the wind, so electricity can be generated through both revolution and rotation. According to this embodiment, a highly efficient wind turbine generator 1 can be realized due to the synergistic effect of the propulsive force (revolution of the blades 82A to 82E) and the rotational force (rotation of the blades 82A to 82E).

[0094] <Second embodiment> A wind turbine sail according to a second embodiment will be described below. In the following description, parts having the same functions as those described in the first embodiment will be given the same names and symbols, and specific descriptions of their functions will be omitted.

[0095] Fig. 19 is a perspective view of a first position of a plurality of blades in a wind-powered propulsion device 401 of the second embodiment, as seen from one side. Fig. 20 is a perspective view of a second position of a plurality of blades in a wind-powered propulsion device 401 of the second embodiment, as seen from one side. In Figs. 19 and 20, the tip plate and other components of the assembly are not shown.

[0096] 19 and 20, in the second embodiment of the wind propulsion device 401, the blades are twisted so that a first imaginary straight line FL1 connecting both ends of each of the blades at a first position on the second rotation axis RC2 (the first imaginary straight line FL1 for one blade is shown in the figure) and a second imaginary straight line FL2 connecting both ends of each of the blades at a second position on the second rotation axis RC2 that is different from the first position (the second imaginary straight line FL2 for one blade is shown in the figure) intersect when viewed from a direction along the second rotation axis RC2 (an example of a predetermined direction).

[0097] In the example shown in the figure, the six blades are twisted so that a first imaginary straight line FL1 at a first position on the second rotation axis RC2 and a second imaginary straight line FL2 at a second position on the second rotation axis RC2 intersect when viewed along the second rotation axis RC2. In other words, the six blades are twisted so that a cross section perpendicular to the direction along the second rotation axis RC2 is the same at any position on the second rotation axis RC2. Note that the twisting manner (shape, etc.) of the multiple blades is not limited to the above and can be changed according to design specifications.

[0098] Figure 21 is an explanatory diagram of the operation of the wind-powered propulsion device 401 of the second embodiment. Also referring to Figure 21, according to this embodiment, by twisting and extending multiple parallel blades in the height direction, an updraft is generated, maintaining air circulation beyond the blade tips and reducing induced drag. Note that when rotating in the opposite direction, a downdraft occurs, but the same effect can be achieved.

[0099] In this embodiment, propulsive force can be generated by the following (1) to (5): (1) Natural wind blows in the direction of the arrow. (2) Natural wind rotates the blades, generating a circulating current. (3) The twisting effect of the blades generates an updraft. (4) The circulating air current created by the blades is carried upward by the updraft. (5) The action of the natural wind and the circulating current generates a propulsive force (Magnus force) in a direction perpendicular to the wind in (1).

[0100] In the wind propulsion device 401 according to this embodiment, the blades are twisted so that a first imaginary straight line FL1 connecting the ends of each of the blades at a first position on the second rotation axis RC2 intersects with a second imaginary straight line FL2 connecting the ends of each of the blades at a second position on the second rotation axis RC2 that is different from the first position. This configuration allows the blades to be twisted along the second rotation axis RC2, thereby generating an airflow along the second rotation axis RC2. This reduces induced drag and ultimately improves propulsion efficiency.

[0101] FIG. 22 is a diagram showing a modified example of a shape in which multiple blades are twisted. Also referring to FIG. 22 , two blades facing each other via a support on the second rotation axis RC2 may be twisted so that a first imaginary line at a first position on the second rotation axis RC2 and a second imaginary line at a second position on the second rotation axis RC2 intersect when viewed from the direction along the second rotation axis RC2. For example, if multiple stages of assemblies are provided, a 60-degree twist may be applied to the blades per stage of the assembly. Note that the twisting manner (e.g., angle) of the blades in the assembly is not limited to the above and can be changed according to design specifications.

[0102] According to this modification, vibrations can be canceled by twisting the blades. For example, if multiple assemblies are provided, adding a predetermined angle of twist to each assembly stage will smooth out the characteristics. This further reduces the dependence of the propulsive force obtained from the wind on the rotation angle, and reduces the effects of the aspect ratio (e.g., induced drag).

[0103] Alternatively, the twist may be reversed at an intermediate position, or a unit twisted in the opposite direction may be placed on top of a unit with a twist. This also cancels out moment vibrations.

[0104] <Third embodiment> A wind turbine sail according to a third embodiment will be described below. In the following description, parts having the same functions as those described in the first embodiment will be given the same names and symbols, and specific descriptions of their functions will be omitted.

[0105] Fig. 23 is a side view including a longitudinal section of the blade of the third embodiment, Fig. 24 is a view including a transverse section of the blade of the third embodiment, and Fig. 25 is a view of the blade of the third embodiment as seen from one side of the second rotation shaft.

[0106] 23 to 25 , the blade according to the third embodiment further includes a shaft portion 530 provided on an upper portion of an assembly 504 extending along a second rotation axis RC2, a cover 531 connected to the shaft portion 530 so as to be movable up and down, and a drive portion 532 (e.g., a motor or the like) that moves the cover 531 between a non-operating position that covers the assembly 504 and an operating position that does not cover the assembly 504. The cover 531 rotates integrally with the assembly 504.

[0107] For example, cover 531 may be connected to assembly 504 via slide structures 535A and 535B so that it can be raised and lowered. In the example shown in the figure, the concave-convex structure of slide structures 535A and 535B includes four recesses 535A formed at equal intervals on the outer periphery of a cylindrical portion constituting assembly 504, and convex portions 535B formed at equal intervals on the inner periphery of cover 531 and fitted into recesses 535A. Note that the slide structure is not limited to the above-described concave-convex structure and can be changed according to design specifications.

[0108] For example, the coupling structure between the shaft portion 530 and the drive portion 532 may be configured to include a mechanism such as a rack and pinion or a ball screw. For example, if the shaft portion 530 has a male thread, the drive portion 532 may have a female thread that meshes with the male thread at the coupling portion with the shaft portion 530. Note that the coupling structure between the shaft portion 530 and the drive portion 532 is not limited to the above and can be changed according to design specifications.

[0109] Although not shown, for example, a reinforcing member for reinforcing the blade may be provided in a region that overlaps the support plate 25 on the hub 83 when the blade is viewed from one side of the second rotation axis RC2 and between the wings (shown by dashed lines in FIG. 25 ). For example, the reinforcing member may be configured to include a strut that runs along the second rotation axis RC2. For example, the form of the reinforcing member can be changed according to design specifications.

[0110] Fig. 26 is a diagram showing an example of the action of the blade of the third embodiment. Fig. 27 is a diagram showing an example of the operation of the blade of the third embodiment. Fig. 28 is a diagram showing another example of the operation of the blade of the third embodiment. With reference to Figs. 26 to 28 together, in this embodiment, when the assembly 504 is not in operation, the force received in strong winds is reduced by the cover 531, and when in operation, the rotation of the cover 531 produces the Magnus effect, thereby generating propulsive force.

[0111] 26, for example, when the assembly 504 is not in operation, the cover 531 is lowered to cover the entire assembly 504. This prevents the assembly 504 from being exposed to wind, thereby significantly reducing wind resistance.

[0112] 27 , for example, the cover 531 can be raised and lowered depending on whether the assembly 504 is in operation or not. For example, the raising and lowering operation of the cover 531 may be performed by controlling the drive unit 532 (for example, by controlling the rotation direction of the motor).

[0113] 28, for example, when the assembly 504 is in operation, the cover 531 is rotated in accordance with the rotation of the assembly 504. This allows the Magnus effect to be exerted not only by the assembly 504 but also by the cover 531, amplifying the thrust.

[0114] The blade according to this embodiment further includes a shaft portion 530 provided on an upper portion of the assembly 504 extending along the second rotation axis RC2, a cover 531 connected to the shaft portion 530 so as to be able to move up and down, and a drive portion 532 that moves the cover 531 between a non-operating position that covers the assembly 504 and an operating position that does not cover the assembly 504. With this configuration, the cover 531, which switches the assembly 504 between operating and non-operating, can also obtain the Magnus effect when in operation, thereby improving propulsion efficiency.

[0115] In the blade according to this embodiment, the cover 531 rotates integrally with the assembly 504. According to this configuration, the cover 531 rotates integrally with the assembly 504, and thus the cover 531 can also generate a Magnus force.

[0116] <Modification of Wind Turbine Generator> Fig. 29 is a diagram showing a modification of the wind turbine generator. Referring also to Fig. 29, the wind turbine generator may function as a vertical axis wind turbine in which the first rotation axis RC1 is a vertical axis extending in the vertical direction. In this case, the second rotation axis RC2 corresponds to an axis along the longitudinal direction of the vertical blades.

[0117] When a vertical axis wind turbine has a windmill sail, the influence of natural wind is advantageous on both sides of the windmill sail, but the influence of natural wind is stronger on the windward side than on the leeward side, so rotation of the windmill sail can occur.

[0118] For example, when a windmill sail moves from upwind to downwind, the wind works to its advantage, i.e., a strong wind hits the windmill sail. On the other hand, when a windmill sail moves from downwind to upwind, the wind works against it, but the wind is weakening.

[0119] A flat plate (shown by a two-dot chain line in the figure) may also be attached to the rear of the windmill sail, which will generate a force that causes the windmill sail to constantly revolve even if it is rotating in a fixed direction.

[0120] <Modifications> The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

[0121] A program for realizing the functions of the control unit according to the above-described embodiments may be recorded on a computer-readable recording medium, and the program may be loaded into a computer system and executed to perform processing. Note that the term "computer system" may include hardware such as an operating system (OS) or peripheral devices. Furthermore, the term "computer-readable recording medium" refers to a flexible disk, a magneto-optical disk, a read-only memory (ROM), a writable nonvolatile memory such as a flash memory, a portable medium such as a DVD (Digital Versatile Disc), or a storage device such as a hard disk built into a computer system.

[0122] Furthermore, the term "computer-readable recording medium" also includes a device that stores a program for a certain period of time, such as a volatile memory (e.g., DRAM (Dynamic Random Access Memory)) within an information processing device or a client computer system when the program is transmitted via a network such as the Internet or a communication line such as a telephone line. The program may also be transmitted from a computer system storing the program in a storage device or the like to another computer system via a transmission medium or by transmission waves within the transmission medium. Here, the "transmission medium" that transmits the program refers to a medium that has the function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line. The program may also be a so-called differential file (differential program) that can realize the aforementioned functions in combination with a program already recorded in the computer system.

[0123] In addition, components in the above-described embodiments may be replaced with well-known components without departing from the spirit of the present invention. Furthermore, the above-described variations may be combined. Among the embodiments disclosed herein, those configured with multiple objects may have the multiple objects integrated together, and conversely, those configured with a single object may be separated into multiple objects. Regardless of whether they are integrated, it is sufficient that the object of the invention can be achieved. Among the embodiments disclosed herein, those in which multiple functions are provided in a distributed manner may have some or all of the multiple functions integrated together, and conversely, those in which multiple functions are provided in a consolidated manner may have some or all of the multiple functions distributed together. Regardless of whether the functions are integrated or distributed, it is sufficient that the object of the invention can be achieved.

[0124] DESCRIPTION OF SYMBOLS 1...wind turbine generator, 7...wind condition acquisition unit, 10A to 10H...blades, 20A, 20B...rotor support unit, 70...rotor shaft body, 71...first generator, 72...second generator, 73...first power generation control unit, 74...second power generation control unit, 75...rotational speed acquisition unit, 76...position detection unit, 80...tower, 81...nacelle, RC1...first rotation shaft, RC2...second rotation shaft

Claims

1. A wind power generation device comprising: a rotor shaft rotatable about a first rotation axis; a first generator that converts the rotational energy of the rotor shaft into electric power; a rotating body connected to the rotor shaft and rotatable about a second rotation axis different from the first rotation axis; blades fixed to the rotating body; and a second generator that converts the rotational energy of the rotating body into electric power.

2. The wind turbine generator according to claim 1, further comprising: a tower; and a nacelle rotatably supported on said tower, said first generator being housed in said nacelle.

3. The wind power generation device according to claim 1 or 2, further comprising: a first power generation control unit that controls the first generator; and a second power generation control unit that controls the second generator.

4. A wind power generation device as described in claim 3, further comprising: a rotational speed acquisition unit that detects the actual rotational speed of the rotor shaft or the first generator; and a wind condition acquisition unit that acquires wind condition information including a current wind speed, wherein the first power generation control unit controls the first generator based on a comparison result between the actual rotational speed and a rated rotational speed, and the second power generation control unit controls the second generator based on the wind condition information.

5. The wind power generation device according to claim 4, wherein the second power generation control unit controls the second generator to decelerate the rotation of the rotor when the current wind speed is equal to or greater than a threshold value.

6. The wind power generation device as described in claim 3, further comprising a position detection unit that detects the tip position of the blade, and wherein the second power generation control unit controls the second generator to decelerate rotation of the rotor when the detected tip position of the blade is equal to or greater than a height threshold.

7. A wind power generation device as described in claim 3, further comprising a wind condition acquisition unit that acquires wind condition information including a current wind speed, wherein the second power generation control unit controls the second generator to decelerate rotation of the rotating body when the actual rotation speed of the first generator is faster than the current wind speed.

8. The wind power generation device according to claim 3, wherein the second power generation control unit controls the second generator so as to change the speed of rotation of the rotors on the left and right of the revolution position.

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