Wave energy power generation device

Abstract

The present invention addresses the problem of providing a wave power generation device capable of maintaining the power generation efficiency of a power generation unit in a high state. In order to solve the problem, the present invention provides a wave energy power generation device which comprises a buoy floating on the water surface and a power generation unit for converting vertical variation of the buoy caused by waves generated on the water surface or in the water into electric power, and which is provided with: a buoy state detection unit for detecting the state of the buoy; detecting the state of the buoy; and a control unit that controls the power generation unit. The control unit changes a speed proportional constant and a position proportional constant, which are constituent elements of a control load provided by the power generation unit, in accordance with the state of the buoy so as to maintain the power generation unit in a state in which the power generation efficiency is high. The control unit changes the velocity proportional constant and the position proportional constant to perform tuning control for maintaining a resonance state between a natural vibration frequency of the float and a vibration frequency caused by a vertical variation of the float, by changing the velocity proportional constant and the position proportional constant. The control unit electrically controls the power generation unit so as to implement the tuning control.

Description

Technical Field

[0001] The present invention relates to a wave energy power generation device, and more particularly to a wave energy power generation device that applies a control method capable of maintaining the power generation efficiency of a generator at a high level. Background Art

[0002] In recent years, in order to ensure that more people can obtain affordable, reliable, sustainable and advanced energy, research and development related to renewable energy that helps to improve energy efficiency are underway.

[0003] In Patent Document 1, a configuration is disclosed: in a wave energy power generation device having a buoy floating on the water surface and a generator that converts the vertical movement of the buoy caused by waves generated on the water surface into electricity, as a control method for the generator to improve power generation efficiency, it can be arbitrarily selected from an impedance control method, a resonance control method, an effective wave period tuning control method, a model predictive tuning method, etc.

[0004] [Prior Art Documents]

[0005] (Patent Document)

[0006] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2021-161990 Summary of the Invention

[0007] [Problems to be Solved by the Invention]

[0008] However, even when the tuning control disclosed in Patent Document 1 is applied, due to the irregular variation of the period of natural waves generated by the sea surface or the like, there is still a problem that it is difficult to continuously capture its peak even if it is desired to make the period of the waves resonate with the natural vibration frequency of the buoy to improve power generation efficiency.

[0009] The object of the present case is to construct a control method that can maintain the power generation efficiency of the wave energy power generation device at a high level in order to solve the above problems. And, furthermore, it contributes to the improvement of energy efficiency.

[0010] [Technical Means for Solving the Problems]

[0011] In order to achieve the foregoing object, a first feature of the present invention is that a wave energy power generation device has a buoy floating on the water surface and a power generation unit that converts the vertical movement of the buoy caused by waves generated on the water surface or in the water into electricity, and the wave energy power generation device includes: a buoy state detection unit that detects the state of the buoy; and a control unit that controls the power generation unit; and, the control unit changes the speed proportionality constant and the position proportionality constant, which are components of the control load provided by the power generation unit, in such a way as to keep the power generation unit in a state of high power generation efficiency according to the state of the buoy.

[0012] Further, the second feature is that the control unit performs tuning control by changing the speed proportional constant and the position proportional constant, and the tuning control is to maintain the resonance state between the natural vibration frequency of the buoy and the vibration frequency caused by the vertical movement of the buoy.

[0013] Further, the third feature is that the control unit performs electrical control on the power generation unit in a manner to achieve the aforementioned tuning control.

[0014] Further, the fourth feature is that the control unit changes the speed proportional constant and the position proportional constant every predetermined time.

[0015] Furthermore, the fifth feature is that the state of the buoy is the displacement and speed of the buoy.

[0016] (Effects of the Invention)

[0017] According to the first feature, in the wave energy power generation device, there is a buoy floating on the water surface and a power generation unit that converts the vertical movement of the buoy caused by waves generated on the water surface or in the water into electricity, and the wave energy power generation device includes: a buoy state detection unit that detects the state of the buoy; and a control unit that controls the power generation unit; and the control unit changes the speed proportional constant and the position proportional constant, which are the components of the control load provided by the power generation unit, in a manner to keep the power generation unit in a state of high power generation efficiency according to the state of the buoy. Therefore, by changing the speed proportional constant and the position proportional constant according to the state of the buoy, even if the height, intensity, or period of the waves changes, the wave energy power generation device can be operated while maintaining a state of high power generation efficiency.

[0018] According to the second feature, the control unit performs tuning control by changing the speed proportional constant and the position proportional constant, and the tuning control is to maintain the resonance state between the natural vibration frequency of the buoy and the vibration frequency caused by the vertical movement of the buoy. Therefore, a large displacement can be obtained by making the natural vibration frequency of the buoy resonate with the vibration frequency caused by the vertical movement of the buoy, and the time average of (speed × load) = the time average of the output can be increased to improve the power generation efficiency.

[0019] According to the third feature, the control unit performs electrical control on the power generation unit in a manner to achieve the aforementioned tuning control. Therefore, for example, the tuning control can be achieved only by using electrical control without using a variable mechanism that physically changes the natural vibration frequency of the buoy.

[0020] According to the fourth feature, the control unit changes the speed proportional constant and the position proportional constant at regular intervals. Therefore, for example, by changing the speed proportional constant and the position proportional constant at very short intervals, even if the state of the waves changes dynamically, the power generation efficiency can be maintained at a high level.

[0021] According to the fifth feature, the state of the buoy is the displacement and speed of the buoy. Therefore, tuning control can be performed based on the displacement of the buoy detected by the sensor and the speed calculated from the displacement without using special equipment or the like. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a block diagram showing the overall configuration of a wave energy power generation device according to an embodiment of the present invention.

[0023] Figure 2 is a vibration model that schematizes the vertical movement of the buoy.

[0024] Figure 3 is an equation for deriving the control load provided to the power generation unit and the output of the power generation unit.

[0025] Figure 4 is a graph showing the operating state of the power generation unit accompanying the vertical movement of the buoy.

[0026] Figure 5 is a diagram showing the concept of the tuning control of the present embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Figure 1 is a block diagram showing the overall configuration of a wave energy power generation device 1 according to an embodiment of the present invention. The wave energy power generation device 1 includes a buoy 2 floating on the surface of the sea or the like, a buoy state detection unit 3 for detecting the state of the buoy 2, a power generation unit 4 for converting the vertical movement of the buoy 2 caused by waves generated on the water surface into electricity, and a control unit 5 for controlling the power generation unit 4.

[0028] The buoy state detection unit 3 may include a sensor for detecting the displacement of the vertical movement of the buoy 2 and a timer for measuring a predetermined time. Further, the buoy state detection unit 3 calculates the speed based on the displacement of the vertical movement of the buoy 2 and transmits the displacement and speed of the buoy 2 to the control unit 5. The control unit 5 composed of a microcomputer or the like performs electrical control on the power generation unit 4 composed of a rotary power generation mechanism based on the displacement and speed of the buoy 2. Between the buoy 2 and the power generation unit 4, a rack-and-pinion mechanism (not shown) or the like for converting linear motion into rotary motion is provided.

[0029] The wave energy power generation device 1 is a so-called translational rocking type that converts the vertical movement of the buoy 2 into electricity. In addition to the landing type in which the lower end of the pillar supporting the buoy 2 is fixed to the seabed or the like, a floating type in which the entire wave energy power generation device floats on the water surface can also be adopted. The buoy 2 can be, for example, a cylindrical shape with a diameter of several meters. In addition, the power generation unit 4 is not limited to a rotary generator, and a linear generator that directly converts linear motion into electricity can also be adopted.

[0030] Figure 2 It is a vibration model that schematizes the vertical movement of the buoy 2. When representing the buoy 2 that moves up and down due to the waves on the water surface with a vibration model, the mass of the buoy 2 that moves up and down due to the wave energy hXe can be expressed as Mf + m. Here, m is the mass of the water that makes the same movement as the buoy 2 and is a function of the angular velocity ω of the buoy 2. In addition, the wave energy hXe is expressed as the wave height h × the wave force coefficient Xe.

[0031] The drag coefficient (viscous damping coefficient) C of the damping model 10 includes the wave-making damping force generated when the buoy 2 displaces water, the mechanical resistance generated by a rack and pinion mechanism, etc., and the generator loss. In addition, the spring constant K of the spring model 11 includes the buoyancy and gravity applied to the buoy 2.

[0032] The wave energy power generation device 1 of the present embodiment can maintain the resonance state between the natural vibration frequency of the buoy 2 and the vibration frequency caused by the vertical movement of the buoy 2, and keep the power generation efficiency of the power generation unit 4 in a high state by changing the components of the control load Ft provided to the power generation unit 4 at regular intervals, that is, the speed proportionality constant ev of the variable damping model 10 and the position proportionality constant ex of the variable spring model 21.

[0033] Figure 3 It is an equation for deriving the control load Ft provided to the power generation unit 4 and the output P of the power generation unit 4. Equation (1) shows that the control load Ft is derived by subtracting the position proportionality constant ex × z from the negative speed proportionality constant ev × z. Here, z is the displacement of the vertical movement of the buoy 2, and z is the time differential of the displacement z. The displacement z is derived based on the time-averaged water surface considering the tide level.

[0034] In addition, Equation (2) shows that the average value of the output P is derived by averaging the value obtained by multiplying the control load Ft by z. Since the output under the item of the position proportionality constant ex becomes zero when averaged, the average value of the output P is the value obtained by multiplying the negative speed proportionality constant ev by the average value of z × z.

[0035] Figure 4It is a graph showing the operating state of the power generation unit 4 accompanying the vertical movement of the buoy 2. The upper mark shows the relationship between the speed v of the buoy 2, the control load Ft, and the time t. In addition, the lower mark shows the relationship between the output P of the power generation unit 4 and the time t. At time t1, since the control load Ft is zero, the output P is zero. In addition, at time t2, since the speed v is zero, the output P is zero.

[0036] On the other hand, at time t3, the sign of the control load Ft is positive, and at the same time, the sign of the speed v is negative. Thus, the signs of the two become different signs, and it becomes a regenerative state where power is supplied from the power generation unit 4. In addition, at time t5, the sign of the control load Ft is negative, and at the same time, the sign of the speed v is positive. Thus, the signs of the two become different signs, and it becomes a regenerative state where power is supplied from the power generation unit 4.

[0037] Furthermore, at time t4, the sign of the control load Ft is negative, and at the same time, the sign of the speed v is negative. Thus, the signs of the two become the same sign, and it becomes an operating state where power is supplied to the power generation unit 4. At time t6, the sign of the control load Ft is positive, and at the same time, the sign of the speed v is positive. Thus, the signs of the two become the same sign, and it becomes an operating state where power is supplied to the power generation unit 4.

[0038] Figure 5 It is a diagram showing the concept of the tuning control of the present embodiment. In the conventional impedance control, only the speed proportionality constant ev is changed, while the wave power generation device 1 of the present embodiment performs tuning control to maintain a high power generation efficiency state by changing both the speed proportionality constant ev and the position proportionality constant ex. The tuning control can make the wave fluctuations resonate with the vertical vibration of the buoy to obtain a large displacement, increasing the time average of (speed × load) = the time average of the output.

[0039] If the position proportionality constant ex is changed, the resonance period can be changed. Specifically, if the position proportionality constant ex is increased, the resonance period becomes shorter. On the contrary, if the position proportionality constant ex is decreased, the resonance period becomes shorter. On the other hand, if the speed proportionality constant ev is changed, the damping force can be changed. Specifically, if the speed proportionality constant ev is increased, the damping force becomes larger. If the speed proportionality constant ev is decreased, the damping force becomes smaller.

[0040] If the damping force is too small, the energy balance becomes negative, and if it is slightly larger, the energy balance becomes zero. Moreover, when it is of an appropriate magnitude, the energy balance becomes positive, and if it is too large, the buoy 2 stops vibrating. In the present embodiment, in a state where the energy balance is positive, the position proportionality constant ex and the velocity proportionality constant ev are changed every predetermined time (e.g., 1 second) in such a manner that the resonance state between the natural vibration frequency of the buoy and the vibration frequency caused by the vertical movement of the buoy 2 is maintained to keep the peak state of the power generation efficiency. The peak state of the power generation efficiency can be determined by numerical analysis using a model.

[0041] The control unit 5 performs electrical control on the power generation unit 4 in such a manner as to achieve tuning control for maintaining the peak state of the power generation efficiency described above. Thereby, even if the state of the waves on the water surface or in the water changes dynamically, the power generation efficiency can be maintained at a high level. In addition, tuning control can be achieved only by electrical control without using a variable mechanism or the like that physically changes the natural vibration frequency of the buoy.

[0042] The structure and size of the wave energy power generation device, the shape and structure of the buoy, the shape and structure of the generator, the natural vibration frequency of the buoy, the predetermined time for updating the velocity proportionality constant and the position proportionality constant, etc. are not limited to the above-described embodiment, and various modifications can be made. For example, in the above-described embodiment, the wave energy generator has been described as a translational rocking type, but it may also be a bending rocking type having a joint portion that rotates due to wave energy or a pendulum type having a pendulum that swings due to wave energy. In addition, a mechanism for changing the natural vibration frequency of the buoy may be provided to maintain the resonance state by driving this mechanism. Furthermore, not only a sensor for detecting the displacement of the buoy but also a sensor for directly detecting the displacement of the waves may be provided to further improve the accuracy of tuning control. The wave energy power generation device of the present invention can be installed in various places such as the sea, lakes, or ponds where natural waves are generated on the water surface or in the water.

[0043] Reference Numerals

[0044] 1: Wave energy power generation device

[0045] 2: Buoy

[0046] 3: Buoy state detection unit

[0047] 4: Power generation unit

[0048] 5: Control unit

[0049] ev: Velocity proportionality constant

[0050] ex: Position proportionality constant

[0051] Ft: Control load

[0052] P: Output

[0053] z: Displacement of the buoy

[0054] z dot: Time derivative of z

Claims

1. A wave energy power generation device includes a buoy floating on the water surface and a power generation unit that converts the vertical movement of the buoy caused by waves generated on or in the water surface into electricity. The wave energy power generation device further comprises: a buoy state detection unit that detects the state of the buoy; and, a control unit that controls the power generation unit; and, the control unit changes the components of the control load provided by the power generation unit, namely the speed proportionality constant and the position proportionality constant, in such a way as to keep the power generation unit in a state of high power generation efficiency according to the state of the buoy.

2. The wave energy power generation device according to claim 1, wherein, The control unit performs tuning control by changing the speed proportionality constant and the position proportionality constant, and the tuning control is to maintain the resonance state between the natural vibration frequency of the buoy and the vibration frequency caused by the vertical movement of the buoy.

3. The wave energy power generation device according to claim 2, wherein, The control unit performs electrical control on the power generation unit in such a way as to achieve the aforementioned tuning control.

4. The wave energy power generation device according to claim 1 or 2, wherein, The control unit changes the speed proportionality constant and the position proportionality constant every predetermined time.

5. The wave energy power generation device according to claim 1 or 2, wherein, The state of the buoy is the displacement and speed of the buoy.

Images