Wind and wave combined power generation system

Abstract

To provide a wind power / wave power composite power generation device which can reduce an oscillation of a wind power generator by wave energy, and can level a power generation amount as a whole.SOLUTION: A first floating body 2 comprises a wind power generation unit 20. Second floating bodies 3A to 3C comprise wires 6A to 6C having wave power generation units 31, extending in a vertical direction together with the second floating bodies 3A to 3C, connected to either of the second floating bodies 3A to 3C at upper ends, respectively, and connected to two different points of the first floating body 2 at lower ends. The wave power generation units 31 comprise internal structures 32 which are relatively displaceable in a vertical direction with respect to outer shell bodies 30, and connected to the first floating body 2 via the wires 6A to 6C, PTOs 33 for connecting the outer shell bodies 30 and the internal structures 32 in the vertical direction, operating as attenuation factor variable attenuation elements, and withdrawing power which is generated by relative motions of the outer shell bodies 30 and the internal structures 32 in the vertical direction, and connecting bodies 34 for connecting the outer shell bodies 30 and the internal structures 32 in the vertical direction, and having elastic elements.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to a combined wind and wave power generation system. [Background technology]

[0002] Wave power generation devices that generate electricity using the power of waves include floating types that float on the ocean (see, for example, Patent Documents 1 and 2). A floating wind-wave combined power generation device has been disclosed that aims to reduce leveled energy costs by incorporating a wave power generation device installed on a floating body into an offshore wind turbine (see, for example, Patent Documents 3 and 4). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2-230969 [Patent Document 2] Japanese Patent Publication No. 2020-133460 [Patent Document 3] Special Publication No. 2013-515903 [Patent Document 4] Special Publication No. 2022-500582 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] In floating wind and wave combined power generation systems, while the amount of power generated by wave power increases as the waves get larger, there is a drawback in that the orientation of the wind turbines becomes unstable, reducing both the amount of power generated by the wind turbines and their fatigue life.

[0005] This invention was made under the circumstances described above, and aims to provide a combined wind and wave power generation system that can reduce the oscillation of a wind turbine and smooth out the overall power generation amount by utilizing wave energy, regardless of the size of the waves. [Means for solving the problem]

[0006] To achieve the above objective, the wind and wave combined power generation apparatus according to the present invention is A wind power generation unit is installed to generate wind power, and the first floating body floats on the wave surface, At least three second floating bodies are floating on the wave surface, It comprises three wires that extend vertically, each connected at its upper end to one of the second floats, and each connected at its lower end to a different location on the first float, The 2nd floating body is The outer shell floating on the wave surface, It is equipped with a wave power generation unit that performs wave power generation, The aforementioned wave power generation unit is An internal structure that is relatively displaceable in the vertical direction relative to the outer shell and is connected to the first float via the wire, A power takeoff mechanism that extracts electricity generated by the relative vertical motion between the outer shell and the internal structure, and functions as a damping element with a variable damping coefficient that connects the outer shell and the internal structure, A connecting body having an elastic element that connects the outer shell and the internal structure in the vertical direction, It is equipped with.

[0007] In this case, a first sensor for detecting the attitude information of the first floating body, A second sensor for detecting relative displacement information between the outer shell and the internal structure, A control unit that controls the force generated during power takeoff based on the output of the first sensor and the output of the second sensor, Equipped with, It would be acceptable to do so.

[0008] Furthermore, the control unit, The first term increases as the rotation angle and rotation speed in the pitch direction with respect to the wind direction of the first floating body increase, The second term increases as the rotation angle and rotation speed in the roll direction relative to the wind direction of the first floating body increase, The force generated during the power takeoff is controlled to minimize the objective function, which is the sum of a third term that increases as the relative displacement and relative velocity between the outer shell and the internal structure increase. It would be acceptable to do so.

[0009] The constraints on the aforementioned objective function include the equation of state as the first condition. The aforementioned equation of state is, The state equation is linearly approximated such that the rotation angle and rotation speed of the first float in the pitch direction, the rotation angle and rotation speed of the first float in the roll direction, and the relative displacement and relative velocity between the outer shell and the internal structure are elements of the state vector, and the force generated during the power takeoff is an element of the input vector. It would be acceptable to do so.

[0010] The constraints on the aforementioned objective function include: The second condition is that the absolute value of the force generated during the aforementioned power takeoff does not exceed a possible magnitude. It would be acceptable to do so.

[0011] The second condition mentioned above includes: The direction of the force generated during the power takeoff is the same as the direction of the relative velocity between the outer shell and the internal structure. The absolute value of the force generated during the power takeoff does not exceed the product of the absolute value of the relative velocity between the outer shell and the internal structure and the damping coefficient of the power takeoff. This includes satisfying all of the following conditions: the absolute value of the force generated during the power takeoff does not exceed the maximum allowable value for wave power generation. It would be acceptable to do so.

[0012] The at least three second floating bodies are arranged in a manner that is rotationally symmetrical by n (where n is an integer of 2 or more) times with respect to the center of the first floating body when viewed in the vertical direction, and is symmetrical or asymmetrical with respect to a line passing through the center. It would be acceptable to do so. [Effects of the Invention]

[0013] According to the present invention, a first floating body that generates wind power and a second floating body that generates wave power are connected by a wire. This allows the first and second floating bodies to maintain independent attitudes, and the attitude of the first floating body can be controlled by the second floating body. Therefore, regardless of the wave size, wave energy can be used to reduce the oscillation of the wind turbine and smooth out the overall power generation. [Brief explanation of the drawing]

[0014] [Figure 1] (A) is a perspective view showing the overall configuration of a combined wind and wave power generation system according to an embodiment of the present invention. (B) is a schematic diagram showing the configuration of the connection portion between the first floating body and the second floating body in the combined wind and wave power generation system. (C) is a schematic diagram showing the internal configuration of the second floating body. [Figure 2] (A) is a schematic diagram showing the configuration of a linear power take-off (PTO). (B) is a schematic diagram showing the configuration of a hydraulic PTO. [Figure 3] Figure 1 is a schematic diagram showing the coordinate system applied to the control of the combined wind and wave power generation system. [Figure 4] This graph compares the pulse response of the pitch degrees of freedom and the pulse response of the relative displacement at power takeoff of the full model of the combined wind and wave power generation system shown in Figure 1 with the pulse response of the pitch degrees of freedom and the pulse response of the relative displacement at power takeoff of the linear model represented by the equation of state. [Figure 5] (A) and (B) are block diagrams showing the configuration of the control system for a combined wind and wave power generation system. [Figure 6] This is a graph showing the second constraint condition. [Figure 7] (A) is a graph showing the standard deviation of the roll degrees of freedom when controlled by various models under various ocean conditions. (B) is a graph showing the standard deviation of the pitch degrees of freedom when controlled by various models under various ocean conditions. [Figure 8] This graph shows the power generated by wave power generation units under various oceanographic conditions. [Figure 9] (A), (B), and (C) are perspective views showing other examples of the overall configuration of the combined wind and wave power generation system in Figure 1. [Modes for carrying out the invention]

[0015] Embodiments of the present invention will be described in detail below with reference to the drawings. In each drawing, the same or equivalent parts are denoted by the same reference numerals.

[0016] [Overall structure] As shown in Figure 1(A), the combined wind and wave power generation device 1 according to this embodiment is a floating body that floats on a water surface such as the sea surface, i.e., on a wave surface, and performs both wind power generation and wave power generation. As shown in Figures 1(A) and 1(B), the combined wind and wave power generation device 1 comprises a first floating body 2 that floats on the wave surface, and three second floating bodies 3A, 3B, and 3C that float on the same wave surface.

[0017] Viewed from above, the three second floating bodies 3A to 3C are arranged radially around the first floating body 2. That is, viewed from above, the three second floating bodies 3A to 3C are positioned at the vertices of an equilateral triangle, and the first floating body 2 is positioned at the centroid of that equilateral triangle. The first floating body 2 is connected by three mooring ropes 4, each with an anchor (not shown) fixed to the seabed or the like attached to its tip, thus preventing it from drifting.

[0018] More specifically, the first floating body 2 comprises a central floating body 10 and cylindrical floating bodies 11A, 11B, and 11C. The central floating body 10 and the cylindrical floating bodies 11A to 11C are columns, or columnar floating bodies. The central floating body 10 and the cylindrical floating bodies 11A to 11C are connected by rod-shaped rigid members 12, and their relative positions are fixed. When viewed from above, the cylindrical floating bodies 11A to 11C are positioned at the vertices of an equilateral triangle. Rod-shaped support levers 13 are formed on the bottom surfaces of the cylindrical floating bodies 11A to 11C, extending in the opposite direction from the central floating body 10. Thus, the first floating body 2 comprises the central floating body 10, the cylindrical floating bodies 11A to 11C, the rigid members 12, and the support levers 13, and these together form a structure that floats on the wavefront.

[0019] As shown in Figure 1(B), the first floating body 2 and the second floating body 3A are connected by wire 6A, the first floating body 2 and the second floating body 3B are connected by wire 6B, and the first floating body 2 and the second floating body 3C are connected by wire 6C. Wires 6A to 6C are preferably made of a material that is difficult to cut, such as metal.

[0020] Wires 6A to 6C each extend in the vertical (heave) direction. The upper ends of wires 6A to 6C are connected to one of the second floating bodies 3A to 3C. Specifically, the upper end of wire 6A is connected to the second floating body 3A, the upper end of wire 6B is connected to the second floating body 3B, and the upper end of wire 6C is connected to the second floating body 3C. Furthermore, the lower end of wire 6A is connected to a support lever 13 extending from the cylindrical floating body 11A below the wavefront, the lower end of wire 6B is connected to a support lever 13 extending from the cylindrical floating body 11B below the wavefront, and the lower end of wire 6C is connected to a support lever 13 extending from the cylindrical floating body 11C below the wavefront. In other words, the lower ends of the second floating bodies 3A to 3C are connected to different points on the first floating body 2 via wires 6A to 6C.

[0021] Returning to Figure 1(A), the first floating body 2 is equipped with a wind power generation unit 20 that generates wind power. The wind power generation unit 20 is located at the upper end of the central floating body 10. The wind power generation unit 20 comprises a column 21 supported by the central floating body 10, a nacelle 22 located at the tip of the column 21, and a plurality of rotor blades 23 rotatably mounted relative to the nacelle 22. Inside the nacelle 22 is a wind turbine generator (not shown) that generates electricity by the rotation of the blades 23. Inside the nacelle 22 are power transmission cables (not shown) that transmit the power generated by the wind turbine generator to the outside of the combined wind and wave power generation device 1. Note that the wind power generation unit 20 is not limited to the configuration shown in Figures 1(A) to 1(C), and any configuration of a generator capable of generating electricity from wind power is acceptable.

[0022] The second floating bodies 3A to 3C each comprise an outer shell 30 that floats on the wavefront and a wave power generation unit 31 that generates wave power. As shown in Figure 1(C), the wave power generation unit 31 comprises an internal structure 32, a PTO 33, and a connector 34. The internal structure 32 is enclosed within the outer shell 30, is displaceable relative to the outer shell 30 in the heave direction, and is connected to the first floating body 2 via wires 6A to 6C. The PTO 33 extracts power generated by the relative vertical motion between the outer shell 30 and the internal structure 32, and functions as a damping element with a variable damping coefficient that generates a force between the outer shell 30 and the internal structure 32 in the same direction as the relative vertical velocity between them. The connector 34 comprises an elastic element 34a and a damping element 34b that connect the outer shell 30 and the internal structure 32 in the heave direction.

[0023] The PTO 33 may be a linear type PTO having a stator 33a fixed to the outer shell 30 and a movable element 33b composed of permanent magnets as an internal structure 32, as shown in Figure 2(A). In this linear type PTO, power generated by the relative vertical motion of the stator 33a and the movable element 33b is extracted, and it also functions as a damping element that generates a force between the stator 33a and the internal structure 32 in the same direction as the relative vertical velocity between the stator 33a and the internal structure 32.

[0024] Furthermore, the PTO 33 may be a hydraulic PTO, as shown in Figure 2(B), comprising a hydraulic cylinder 33c whose outer surface is fixed to the outer shell 30 and whose internal piston forms the internal structure 32, a hydraulic motor 33d, and a generator 33e. In this hydraulic PTO, the power generated by the relative vertical motion between the housing and piston of the hydraulic cylinder 33c is extracted from the generator 33e, and the hydraulic motor 33d functions as a damping element that generates a force between the housing and piston of the hydraulic cylinder 33c in the same direction as the relative vertical velocity between them.

[0025] The configuration of the second floating bodies 3A and 3B is the same as that of the second floating body 3C shown in Figure 1(C). Power transmission cables (not shown) are installed on the second floating bodies 3A to 3C to transmit the generated power extracted by the PTO 33 to the outside of the combined wind and wave power generation device 1.

[0026] The connecting body 34 comprises an elastic element 34a with a fixed elastic modulus and a damping element 34b with a fixed damping coefficient.

[0027] As described above, one end of each wire 6A to 6C is connected to a support lever 13 extending from the cylindrical floats 11A to 11C of the first float 2, and the other end is connected to the internal structure 32 of the second floats 3A to 3C. By adjusting the force with which the internal structures 32 of the three second floats 3A to 3C pull on the cylindrical floats 11A to 11C via the wires 6A to 6C, it is possible to control the attitude of the first float 2.

[0028] [Coordinate system] The position and orientation of the combined wind and wave power generation device 1 are defined based on the orthogonal coordinate system of x, y, and z axes shown in Figure 3. This coordinate system is a right-handed coordinate system, and the static water surface (sea surface when there are no waves) is defined as the xy plane. The x-axis coincides with the average wind direction (+x direction is upwind). In this embodiment, the wind direction is assumed to be approximately constant. The z-axis is defined along the centerline passing through the axis of the cylindrical central floating body 10. That is, with the wind power generation unit 20 as the reference point, and the upwind direction being forward, the x-axis direction is the surge direction, the y-axis direction is the sway direction, and the z-axis direction is the heave direction. Also, θx around the x-axis is the roll direction, θy around the y-axis is the pitch direction, and θz around the z-axis is the yaw direction. The following explanation will use this 6-degree-of-freedom coordinate system.

[0029] [Full mathematical model of a combined wind and wave power generation system] As shown in FIGS. 1(A) and 1(B), the wind and wave power combined power generation device 1 includes a first floating body 2 and three second floating bodies 3A to 3C, and the first floating body 2 and the second floating bodies 3A to 3C are connected by wires 6A to 6C. If the first floating body 2 and the three second floating bodies 3A to 3C are each rigid bodies, the wind and wave power combined power generation device 1 can be regarded as a four-body structure. If the first floating body 2 and the three second floating bodies 3A to 3C are each an object with i = 1 to 4, the equation of motion (fluid-memory model), which is a full model representing the motion of each rigid body, is expressed by the following formula.

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[0030] Also, the delay function K ij (t) is expressed by the following formula:

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[0031] To reduce the computational load, the above delay function is approximated by the following linear system.

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[0032] On the other hand, in the wind power generation unit 20, the thrust F applied to the rotor of the generator tand aerodynamic torque T R The dimensionless thrust coefficient C t and the output coefficient C p It can be expressed as follows:

number

[0033] Coefficient C t , C p The aerodynamic load τ in equation (1) above is a function of the pitch angle β and the peripheral speed ratio λ, and is obtained as a lookup table from steady-state simulation. a The thrust F takes into account the height of the hub. t and aerodynamic torque T R It can be calculated from this.

[0034] Furthermore, the force F generated in the wires 6A to 6C connecting the wind power generation unit 20 and the wave power generation unit 31 m This can be modeled as a hybrid system of springs and dampers, as shown in the following equation.

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[0035] Here, the force f generated in the PTO 33 and connecting body 34 of the second floating bodies 3A to 3C is pi It can be expressed by the following formula.

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[0036] [Linear models for controller design] To reduce the complexity of the design of the control unit 40, which will be described later, a linear approximation model (linear model) of the wind-wave combined power generation device 1 near the equilibrium state is defined. In this case, the roll degrees of freedom θx and pitch degrees of freedom θy of the first floating body 2 are denoted by φ and θ, respectively. The heave degrees of freedom of the outer shell 30 in the second floating bodies 3A to 3C are z i Considering the motion of (i=1, 2, 3), the overall equation of motion can be expressed as follows:

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[0037] Considering the oscillation of the first floating body 2, the absolute coordinate displacement z of the outer shell 30 of the second floating body 3 in the heave direction. i (i=1, 2,3) represents the relative displacement z between the outer shell 30 and the internal structure 32. pi This can be converted to (i=1, 2,3).

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[0038] From equations (9) and (10), the equation of state for the entire wind-wave combined power generation device 1 can be rewritten as follows.

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[0039] Also, the vector f(t) is a force vector having as elements the forces generated in the PTOs 33 of the second floating bodies 3A to 3C, and is as follows. f(t)=[f1,f2,f3] T Matrices A, B1, and B2 are system matrices of the state equation.

[0040] Thus, the state equation of Equation (11) is a state equation linearly approximated such that the roll-direction rotation angle φ and rotation speed φ' of the first floating body 2, the pitch-direction rotation angle θ and rotation speed θ' of the first floating body 2, and the relative displacement z p1 ,z p2 ,z p3 and relative speed z p1 ’,z p2 ’,z p3 ’ are elements of the state vector, and the forces generated in the PTO 33 are elements of the input vector.

[0041] When the control system is discretized with a sampling period T s , the state equation (11) can be expressed as follows.

Equation

[0042] The attenuation coefficient matrix Λ in Equation (9) can be obtained by the system identification approach in the above-described full model. Note that since the ocean environment is complex and it is difficult to estimate wave excitation forces and aerodynamic forces, etc., in the controller design, the external load τ ext is ignored.

[0043] In the full model and linear model described above, when a pulse input (pulse input at 10 seconds, pulse output stopped at 15 seconds) is applied as a force f1 element with the force generated at the PTO33 of the second floating bodies 3A-3C, the pitch degree of freedom θ and relative displacement z are determined. p1 The response is shown in Figure 4. As shown in Figure 4, the response of the pitch degrees of freedom θ and the relative displacement z are different for the full model and the linear model. p1 The responses are almost identical. This result indicates that the input-output characteristics of the system can be reproduced with a linear model, and this does not hinder controller design.

[0044] [Model Predictive Control using Mixed Integer Programming] As shown in Figure 5(A), the combined wind and wave power generation system 1 includes a control unit 40. In Figure 5(A), the configuration described above, which includes the first floating body 2 and three second floating bodies 3A to 3C, is combined into a single unit consisting of the control unit 40 and the controlled object 41. The control unit 40 controls the controlled object 41 by performing model predictive control using a mixed integer programming problem.

[0045] The roll degrees of freedom φ and pitch degrees of freedom θ of the first floating body 2, and the relative displacement z between the outer shell 30 and the internal structure 32 in the three second floating bodies 3A to 3C. p1 ,z p2 ,z p3 This is constantly monitored by sensors. As shown in Figure 5(B), the roll degrees of freedom φ and pitch degrees of freedom θ are detected by a gyro sensor 41A, which is attached to the first floating body 2 and acts as the first sensor to detect its attitude information. Relative displacement z p1 ,z p2 ,z p3 This is detected by displacement sensors 41B, 41C, and 41D, which are attached to the second floating bodies 3A to 3C respectively and act as second sensors to detect relative displacement information between the outer shell 30 and the internal structure 32. From the controlled object 41, x(k) = [φ,θ,z p1 ,z p2 ,z p3 ,φ',θ',z p1 ',z p2 ',z p3 '] T The output is the velocity vector [φ',θ',z p1 ',zp2 ',z p3 '] T Each of these elements may be calculated by the control unit 40. Based on the state vector x(k), the control unit 40 calculates the force f generated in the PTO 33 in the second floating bodies 3A to 3C. i The command value is output to the PTO33. In this way, the control unit 40 performs control using the state equation of equation (12) as the first condition among the constraints.

[0046] The control unit 40 controls the force f generated by the relative displacement between the outer shell 30 and the internal structure 32, that is, the force f used for power generation in the wave power generation unit 31. i The controlled object 41 is controlled within the limits of what is possible. For this purpose, for example, the following constraints are set.

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[0047] Furthermore, due to the constraints of the control system, the force f generated in the PTO33 i Since it is necessary to limit the load to within its maximum load, the following constraints are added to the control by the control unit 40.

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[0048] The control unit 40 controls the controlled object 41 in order to minimize the movement of the wind power generation unit 20 in the roll degree of freedom φ and pitch degree of freedom θ, while satisfying the above-mentioned constraints (first condition, second condition) and minimizing the objective function J expressed by the following equation.

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[0049] The control unit 40 solves the following constraint optimization problem at each sampling period, that is, finds the value of f(k+j) that minimizes the objective function J, and outputs it to the controlled object 41 as a command value.

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[0050] (Evaluation results) As shown in Table I below, the control performance of the combined wind and wave power generation system 1 was evaluated by simulation by applying different ocean conditions EC1 to EC6, which describe the operating conditions of the turbine of the wind power generation unit 20. [Table 1] In the table above, u ∞ (z h ) is the average wind speed at the hub height of the wind turbine unit 20. u The turbulence intensity is indicated by Hs, the significant wave height by Tz, and the mean zero-crossing period of the wave by Tz. The conditions set include operating modes below rated, rated, and above rated (EC1-EC4), as well as parking modes for severe and extremely severe weather (EC5, EC6). Note that the turbulence intensity I is... uThis was set according to the IEC (International Electrotechnical Commission) standard, 2nd edition.

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[0051] To investigate the performance of the control unit 40, a simulation was performed. The following three models were set up and compared. Model M1: Individual model consisting only of wind power unit 20 and first floating body 2, excluding wave power unit 31. Model M2: Full model including wave power generation unit 31, without semi-active control. Model M3: Full model with semi-active control, including wave power generation unit 31.

[0052] Figures 7(A) and 7(B) show the standard deviations of the roll degrees of freedom φ and pitch degrees of freedom θ of the first floating body 2 when simulations are performed using models M1 to M3 under oceanographic conditions EC1 to EC6. As shown in Figures 7(A) and 7(B), under moderate ocean conditions (EC1, EC2, etc.), models M2 and M3 have smaller standard deviations of roll degrees of freedom φ and pitch degrees of freedom θ than model M1. Furthermore, when the sea is rough (EC5) or very rough (EC6), model M2, which does not use semi-active control, has larger standard deviations than model M1. In the case of model M3, which implements the proposed semi-active controller, the standard deviations of roll degrees of freedom φ and pitch degrees of freedom θ are reduced, demonstrating the effectiveness of the control. When the sea is very rough (EC6), the proposed controller was able to reduce the standard deviations of roll degrees of freedom φ and pitch degrees of freedom θ of the first floating body 2 by 16%.

[0053] Figure 8 shows a plot of the primary converted power generated by the wave power generation unit 31. As shown in Figure 8, the wave power generation unit 31 accounts for approximately 7% of the power conversion amount of the wind-wave combined power generation device 1 in EC1 to EC4. Furthermore, it was found that the wave power generation unit 31 can ensure a certain amount of power generation even under rough weather conditions and extremely severe ocean conditions EC5 and EC6, and can contribute to stabilizing the power generation capacity of the wind farm.

[0054] As described in detail above, in the wind and wave combined power generation device 1 according to this embodiment, the first floating body 2 that generates wind power and the second floating bodies 3A to 3C that generate wave power are connected by wires 6A to 6C. Therefore, the first floating body 2 and the second floating bodies 3A to 3C can be made to assume independent attitudes, and the attitude of the first floating body 2 can be controlled by the second floating bodies 3A to 3C. For this reason, the overall power generation amount can be smoothed out by utilizing wave energy, regardless of the size of the waves.

[0055] Furthermore, according to this embodiment, the first floating body 2 and the second floating bodies 3A to 3C are connected by wires 6A to 6C that extend in the heave direction. As a result, when the waves are large, the force from the multiple second floating bodies 3A to 3C is exerted via the wires 6A to 6C to maintain the posture of the first floating body 2 in a balanced manner. This prevents a significant loss of power generated by the wind power generation unit 20.

[0056] Furthermore, according to this embodiment, there are terms that increase as the roll degrees of freedom φ and pitch degrees of freedom θ of the first floating body 2 increase, and the relative displacement z between the outer shell 30 and the internal structure 32. pi Optimal control is performed to minimize the objective function J, which is a linear sum of terms that increase as the other factors increase. This enables control that balances the change in the attitude of the first floating body 2 with the relative displacement between the outer shell 30 and the internal structure 32 in the second floating bodies 3A-3C. As a result, it becomes possible to control the attitude of the first floating body 2 with the optimal force.

[0057] Furthermore, according to this embodiment, the elements of the state vector x(k) are the roll degrees of freedom φ and pitch degrees of freedom θ of the first floating body 2, and the relative vertical displacement z between the outer shell 30 and the internal structure 32 in the second floating bodies 3A to 3C. p1 ,z p2 ,z p3 This narrows down the options. As a result, the sensor output used for control can be kept to the bare minimum, thus reducing the amount of computation required for control. By reducing the amount of computation, the sampling time for control can be shortened, improving control accuracy.

[0058] Furthermore, according to this embodiment, the attitude of the first floating body 2 is controlled using only the force generated in the PTO 33 due to the relative displacement between the outer shell 30 and the internal structure 32. This eliminates the need for external power supply.

[0059] Note that the second floating bodies 3A, 3B, and 3C are collectively referred to as the second floating body 3. In the above embodiment, there are three second floating bodies 3. However, this is not the only option. There may be four or more second floating bodies 3. In other words, the wind-wave combined power generation device 1 only needs to have at least three second floating bodies 3. It is desirable that at least three second floating bodies 3 are arranged in a rotationally symmetric manner of n (where n is an integer of 2 or more) rotations with respect to the center of the first floating body 2 when viewed vertically. This makes it easier to calculate the attitude control of the first floating body 2. The wind-wave combined power generation device 1 can have the configuration shown in Figure 9(A). In this configuration, the first floating body 2 has a triangular structure when viewed from above, and the second floating bodies 3 are arranged below the sides of the triangle. The second floating bodies 3A, 3B, 3C, ... may be arranged in a double, triple, or grid pattern with respect to the center of the first floating body 2. Furthermore, as shown in Figure 9(B), the second floating body 3 may be positioned symmetrically with respect to a line L passing through the center of the first floating body 2. However, as shown in Figure 9(C), the second floating body 3 may also be positioned asymmetrically with respect to the center O of the first floating body 2. In this way, the second floating body 3 can be positioned without difficulty even if there are obstacles in the surrounding area. It is desirable that the second floating body 3 be determined according to the characteristics of the installation site of the wind and wave combined power generation device 1. There are no particular restrictions on the positioning of the second floating body 3; it is flexible.

[0060] This invention allows for various embodiments and modifications without departing from the broad spirit and scope of the invention. Furthermore, the embodiments described above are for illustrative purposes only and do not limit the scope of the invention. In other words, the scope of this invention is indicated not by the embodiments, but by the claims. Various modifications made within the scope of the claims and the equivalent scope of the meaning of the invention are considered to be within the scope of this invention. [Industrial applicability]

[0061] The present invention is applicable to a floating power generation device that combines wind power generation and wave power generation. [Explanation of symbols]

[0062] 1 Wind and wave combined power generation device, 2 First floating body, 3, 3A, 3B, 3C Second floating body, 4 Mooring rope, 6A, 6B, 6C Wire, 10 Central floating body, 11A, 11B, 11C Cylindrical floating body, 12 Rigid member, 13 Support lever, 20 Wind power generation unit, 21 Column section, 22 Nacelle, 23 Rotor blade, 30 Outer shell, 31 Wave power generation unit, 32 Internal structure, 33 Power take-off (PTO), 33a Stator, 33b Movable element, 33c Hydraulic cylinder, 33d Hydraulic motor, 33e Generator, 34 Connector, 34a Elastic element, 34b Damping element, 40 Control unit, 41 Controlled object, 41A Gyro sensor (first sensor), 41B, 41C, 41D Displacement sensor (second sensor)

Claims

1. A wind power generation unit is installed to generate wind power, and the first floating body floats on the wave surface, At least three second floating bodies are suspended on the wave surface, It comprises three wires that extend vertically, each connected at its upper end to one of the second floats, and each connected at its lower end to a different location on the first float, The aforementioned second floating body is The outer shell floating on the wave surface, It is equipped with a wave power generation unit that performs wave power generation, The aforementioned wave power generation unit is An internal structure that is relatively displaceable in the vertical direction relative to the outer shell and is connected to the first float via the wire, A power takeoff mechanism that extracts electricity generated by the relative vertical motion between the outer shell and the internal structure, and functions as a damping element with a variable damping coefficient that connects the outer shell and the internal structure, A connecting body having an elastic element that connects the outer shell and the internal structure in the vertical direction, A combined wind and wave power generation system equipped with these features.

2. A first sensor for detecting the attitude information of the first floating body, A second sensor for detecting relative displacement information between the outer shell and the internal structure, A control unit that controls the force generated during power takeoff based on the output of the first sensor and the output of the second sensor, The wind and wave combined power generation apparatus according to claim 1, comprising:

3. The control unit, The first term increases as the rotation angle and rotation speed in the pitch direction with respect to the wind direction of the first floating body increase, The second term increases as the rotation angle and rotation speed in the roll direction relative to the wind direction of the first floating body increase, The force generated during the power takeoff is controlled to minimize the objective function, which is the sum of a third term that increases as the relative displacement and relative velocity between the outer shell and the internal structure increase. The wind and wave combined power generation device according to claim 2.

4. The constraints on the aforementioned objective function include the equation of state as the first condition. The aforementioned equation of state is, The state equation is linearly approximated such that the rotation angle and rotation speed of the first float in the pitch direction, the rotation angle and rotation speed of the first float in the roll direction, and the relative displacement and relative velocity between the outer shell and the internal structure are elements of the state vector, and the force generated during the power takeoff is an element of the input vector. The wind and wave combined power generation apparatus according to claim 3.

5. The constraints on the aforementioned objective function include: The second condition is that the absolute value of the force generated during the aforementioned power takeoff does not exceed a possible magnitude. The wind and wave combined power generation apparatus according to claim 4.

6. The second condition mentioned above includes: The direction of the force generated during the power takeoff is the same as the direction of the relative velocity between the outer shell and the internal structure. The absolute value of the force generated during the power takeoff does not exceed the product of the absolute value of the relative velocity between the outer shell and the internal structure and the damping coefficient of the power takeoff. This includes satisfying all of the following conditions: the absolute value of the force generated during the power takeoff does not exceed the maximum allowable value for wave power generation. The wind and wave combined power generation apparatus according to claim 5.

7. The at least three second floating bodies are arranged in a manner that is rotationally symmetrical by n (where n is an integer of 2 or more) times with respect to the center of the first floating body when viewed in the vertical direction, and is lineally symmetrical or asymmetrical with respect to a line passing through the center. The wind and wave combined power generation apparatus according to claim 1.

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