Magnus wave power generation device

Abstract

The present invention provides a Magnus wave power generation device that can resonate with waves by following large changes in the wave period. [Solution] The main body of the device 10 is configured as an integrated structure with a float section 12, a Magnus turbine power generation section 14, and a weight section 16 arranged from top to bottom. The weight section 16 includes a solid weight 16a and a water tank 16b2. The pump 26 supplies and drains water from around the main body of the device 10 to the water tank 16b2 to adjust the amount of water contained in the water tank 16b2. The wave height change detection unit 36 ​​detects changes in the height of the water surface around the main body of the device 10 due to waves. The control unit 15 detects the period or frequency of a fundamental wave from the changes in water surface height detected by the wave height change detection unit 36, where the wave height value is determined to be above a predetermined value and the frequency of occurrence within a predetermined time is relatively high compared to waves of other periods, and drives the pump 26 to make the natural period of the main body of the device 10 follow the detected fundamental wave period or frequency.

Description

[Technical Field]

[0001] This invention relates to a Magnus wave power generation device that converts the energy of waves from the sea, lakes, etc., into electricity using the Magnus effect. [Background technology]

[0002] The inventors of the present invention have previously proposed a novel Magnus wave power generation device in Patent Document 1 and a resonance control method for a Magnus wave power generation device in Non-Patent Document 1. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2024-17096 [Non-patent literature]

[0004] [Non-Patent Document 1] The paper "Resonance Control Method for a Point Absorber Wave Energy Converter with Magnus Effect-Based Turbine Generator" by K. Yamashita, S. Takekoshi, and S. Katsuki was presented at the International Conference on Electrical Machines and Systems (ICEMS 2023) in Zhuhai, China, November 5-8, 2023. [Overview of the project] [Problems that the invention aims to solve]

[0005] As described in Non-Patent Document 1, in point absorber type power generation such as Magnus wave power generation, wave energy can be efficiently converted into electricity by resonating the movement of the wave and the floating body. Non-Patent Document 1 proposes a resonance control method using electric propulsion utilizing turbine thrust. However, this resonance control method has the problem of having a narrow control range and being unable to cope with large changes in wave period.

[0006] This invention provides a Magnus wave power generation device that can resonate with waves in response to large changes in the wave period. [Means for solving the problem]

[0007] This invention is configured as an integrated structure in which a float section, a Magnus turbine power generation section, and a weight section are arranged vertically and interconnected from top to bottom, the Magnus turbine power generation section comprises a Magnus turbine and generator driven by wave force utilizing the Magnus effect, the weight section comprises a solid weight and a water tank, and the device body section floats in water with at least the upper part of the float section above the water surface when submerged in water, and the amount of water contained in the water tank is adjusted by supplying water from around the device body section to the water tank or draining the water from the water tank to the area around the device body section when the device body section is submerged in water. The device comprises a pump that varies the draft of the main body of the device, thereby varying the natural period of the vertical movement of the main body of the device in water; a wave height change detection unit, which is disposed separately from the main body of the device and detects changes in the height of the water surface around the main body of the device, which is submerged in water, due to waves; and a control unit that, based on the changes in water surface height detected by the wave height change detection unit, determines that the wave component whose wave height value is above a predetermined value and whose occurrence frequency within a predetermined time is relatively high compared to waves of other periods is the fundamental wave, detects the period or frequency of the fundamental wave, and controls the pump to drive the main body of the device to follow the detected period or frequency of the fundamental wave. With this, by adjusting the amount of water contained in the water tank to make the natural period of the main body of the device follow the period of the fundamental wave, the main body of the device can be made to resonate with the wave with a high occurrence frequency and move up and down significantly, thereby obtaining a large power generation output. Furthermore, since the weight section comprises a solid weight and a water tank, the main body of the device can be made smaller compared to a case where the weight section consists only of a water tank (for example, by shortening the overall length of the main body in the vertical direction).

[0008] In this invention, the control unit comprises a water volume characteristic storage unit that stores the characteristics of the water volume of the water tank or a value equivalent to the water volume, which realizes the natural period of the main body of the device corresponding to the period or frequency of the detected fundamental wave, and a water volume detection unit that detects the water volume of the water tank or a value equivalent to the water volume. The control unit reads the water volume of the water tank or a value equivalent to the water volume, corresponding to the period or frequency of the detected fundamental wave, from the water volume characteristic storage unit and controls the pump to drive so that the water volume of the water tank or a value equivalent to the water volume detected by the water volume detection unit follows the water volume or a value equivalent to the water volume read from the water volume characteristic storage unit. With this, even without directly detecting the draft of the main body of the device which is moving up and down due to the waves, the water volume of the water tank or a value equivalent to the water volume can be detected and the main body of the device can be made to resonate with waves that occur frequently. In this case, the pump is driven in a reversible manner to supply water to the tank and drain water from the tank, and the water storage volume detection unit can detect a value equivalent to the water storage volume of the tank by adding the amount of water supplied from the pump to the tank and subtracting the amount of water drained from the tank via the pump. This makes it difficult to directly measure the water storage volume of the tank even when the main body of the device is shaken by waves and the water in the tank is shaken, allowing the water storage volume of the tank to be measured indirectly and the main body of the device to resonate with the waves that occur most frequently. In this case, the control unit can also drive the pump in the draining direction based on a predetermined instruction to return the tank to its initial state where it can no longer drain water, and reset the detected value of the water storage volume detection unit. This makes it possible to eliminate errors between the actual water storage volume of the tank and the indirectly determined water storage volume by subtracting the amount of water supplied and drained, even if errors occur due to prolonged use, by returning the tank to its initial state where it can no longer drain water and resetting the detected value of the water storage volume detection unit.

[0009] In this invention, the pump may be located in the water tank or in a space adjacent to the water tank, below the Magnus turbine power generation unit. With this arrangement, the pump is positioned below the water surface when the main body of the device is submerged in water, and the weight of the pump can be used as part of the counterweight to help maintain a stable upright posture for the main body of the device floating in the water.

[0010] In this invention, the wave height change detection unit may include a wave height meter positioned floating on the water surface near where the main body of the device is deployed. This allows for the detection of changes in the water level around the main body of the device, even when the main body of the device is located far from land.

[0011] In this invention, the control unit can be configured to drive the pump intermittently throughout the day. This is because, in the ocean and lakes, the period of the fundamental wave does not change rapidly (the period of the fundamental wave of ocean waves is usually in the range of a few seconds to tens of seconds), so by adjusting the draft intermittently throughout the day (for example, several times a day), the natural period of the main body of the device can be made to follow the period of the fundamental wave. This reduces the power consumption of the pump compared to when the pump is driven continuously. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 2 shows the main unit and wave height change detection unit of the Magnus wave power generation device, illustrating the device and wave height change detection unit in their operational state when submerged in the sea. The main unit is partially cut to schematically show its internal structure. [Figure 2] This figure shows an embodiment of the Magnus wave power generation device according to this invention, illustrating the overall system configuration of the Magnus wave power generation device in its operating state. [Figure 3] Figure 2 is a block diagram showing an embodiment of the control system for draft control by the control unit. [Figure 4] This block diagram shows an example of a specific method for achieving draft control, as shown in Figure 3. [Figure 5] This block diagram shows another example of a specific method for achieving the draft control shown in Figure 3. [Modes for carrying out the invention]

[0013] Embodiments of this invention will now be described. Figure 2 shows an embodiment of the Magnus wave power generation device according to this invention, and the overall system configuration of the Magnus wave power generation device in operation is shown. The Magnus wave power generation device 1 comprises a device body 10, a wave height meter 36 (wave height change detection unit), and a control unit 15. The device body 10 is submerged in the sea 11 with its upper part protruding from the sea surface 11a. The device body 10 contains a Magnus turbine power generation unit 14, a water tank 16b2, a pump 26, etc. (The detailed configuration of the device body 10 will be described later). The Magnus turbine power generation unit 14 converts the vertical movement of the device body 10 caused by waves into electrical energy using the Magnus effect. By adjusting the amount of water stored in the water tank 16b2 with the pump 26 to adjust the draft of the device body 10, the natural period of the vertical movement of the device body 10 in the sea 11 is adjusted. The lower end of the device body 10 is connected to an anchor 19 via a mooring wire 17. The anchor 19 lands on the seabed 13, allowing vertical movement of the main unit 10 (up and down movement due to normal waves) while suppressing lateral movement. The wave height meter 36 floats on the sea surface 11a near the main unit 10. The wave height meter 36 and the main unit 10 are connected by a cable as needed, and power is supplied to the wave height meter 36 and signals are transmitted through the cable. The wave height meter 36 detects changes in the height of the sea surface 11a due to waves. The control unit 15 detects the period or frequency of the fundamental wave from the change in the height of the sea surface 11a detected by the wave height meter 36, and controls the pump 26 to drive so that the natural period or natural frequency of the main unit 10 follows the detected period or frequency. This causes the main unit 10 to resonate with frequently occurring waves and move significantly up and down, so that a large power output can be obtained from the Magnus turbine power generation unit 14. The main unit 10 is connected to land by a cable 21. Cable 21 contains a power transmission cable for transmitting electricity generated by the Magnus turbine power generation unit 14 to a land base, a power supply cable for supplying power from the base to the main unit 10 of the device necessary for the initial acceleration of the Magnus turbine power generation unit 14 (see Patent Document 1) and driving the pump 26, and a signal cable for sending and receiving signals between the main unit 10 of the device and the base. The control unit 15 can be built into the main unit 10 of the device or located at the base.The wave height meter 36 and the control unit 15 can be connected by wire or wirelessly. The device main body 10 can be equipped with a solar cell and a battery as necessary. The power of the battery can be used as the initial acceleration power supply for the Magnus turbine power generation unit 14, the drive power supply for the pump 26, and the operating power supply for the wave height meter 36, the control unit 15, etc. The battery can also be charged with the generated power of the Magnus turbine power generation unit 14 or the generated power of the solar cell. A solar cell and a battery can also be mounted on the wave height meter 36, the battery can be charged with the generated power of the solar cell, and the battery can be used as the operating power supply for the wave height meter 36.

[0014] Referring to FIG. 1, the configuration of the device main body 10 will be described. The device main body 10 is configured as an integral structure in which the float part 12, the Magnus turbine power generation unit 14, and the weight part 16 are arranged vertically from top to bottom and connected to each other so that their relative positions are fixed (immovable). The device main body 10 is generally vertically long and concentrically cylindrical, and the Magnus turbine power generation unit 14 at an intermediate position in the vertical direction has an outer shape that bulges in the radial direction. The outer surface of the device main body 10 is generally composed of a corrosion-resistant metal member such as stainless steel. The entire outer surface of the device main body 10 can also be painted. The upper and lower ends of the device main body 10 (the upper end of the float part 12 and the lower end of the weight part 16) are each formed in a tapered shape. Since the upper part of the device main body 10 is configured to be light (low density) with the float part 12 and the lower part is configured to be heavy (high density) with the weight part 16, it floats in the sea 11 with the float part 12 on the upper side and the longitudinal direction facing the vertical direction (vertical direction) when placed in the sea 11. At this time, at least the upper part of the float part 12 is in a state of protruding from the sea surface 11a. The device main body 10 moves up and down on the spot due to the wave 11b.

[0015] The float part 12 has a cavity 12b in a watertightly sealed housing 12a. The lower end of the float part 12 is fixedly connected to the upper surface of the structural part (fixed part not shown) of the Magnus turbine power generation unit 14.

[0016] The Magnus turbine power generation unit 14 has a structure in which a Magnus turbine 18 (Magnus blade) driven by wave power using the Magnus effect and power generation units 20 (two in the vertical direction here) each incorporating a generator driven by the Magnus turbine 18 are interconnected via bevel gears and a speed change gear. The Magnus turbine power generation unit 14 can use, for example, the one described in Patent Document 1 above. The power generation unit 20 is fixed to the structural part of the Magnus turbine power generation unit 14. The Magnus turbine 18 and the power generation unit 20 are surrounded by a reducer and a diffuser 22. The reducer and the diffuser 22 have a structure in which two frustoconical shapes (generally funnel shapes) are connected with their tops overlapping each other. The reducer and the diffuser 22 are fixed to the structural part of the Magnus turbine power generation unit 14 in a posture where the central axis of the frustoconical shape is arranged on the central axis 10a of the apparatus main body 10. A cavity 22b communicating with the sea 11 around the apparatus main body 10 is formed on the inner peripheral side of the reducer and the diffuser 22. Openings 22c and 22d are formed at the upper and lower ends of the cavity 22b, respectively. The Magnus turbine 18 is arranged at the vertical center position of the cavity 22b. Since the cross-sectional area in the direction perpendicular to the axis of the cavity 22b is the largest at the positions of the upper and lower openings 22c and 22d and the narrowest at the vertical central part position, as the apparatus main body 10 moves up and down due to the wave 11b, seawater flows in from the upper opening 22c and is discharged from the lower opening 22d (when the apparatus main body 10 rises with respect to the seawater) or flows in from the lower opening 22d and is discharged from the upper opening 22c (when the apparatus main body 10 descends with respect to the seawater), and the Magnus turbine 18 is arranged at the position where the flow velocity of the seawater is the highest (and thus the driving energy is the highest). Therefore, the effect of increasing the power generation output of the power generation unit 20 is obtained by the reducer and the diffuser 22. Note that the outer periphery of the reducer and the diffuser 22 can be surrounded by a cylindrical structure such as stainless steel and the cylindrical structure can be fixed to the reducer and the diffuser 22. The space between the cylindrical structure and the reducer and the diffuser 22 can be structured to be watertightly sealed or not sealed.

[0017] The weight section 16 has its upper end fixedly connected to the lower surface of the structural part of the Magnus turbine power generation section 14. The weight section 16 has a structure in which a solid weight 16a is placed on the lower side and a watertight cavity 16b is placed on the upper side by a housing 16c. The solid weight 16a can be made entirely of a metal block such as stainless steel. Alternatively, the solid weight 16a can be made by filling the internal space of the housing 16c, such as stainless steel, with a high-density material such as metal particles. The cavity 16b is watertightly divided into upper and lower cavities 16b1 and 16b2 by a partition plate 24. The lower cavity 16b2 forms a water tank, and the upper cavity 16b1 forms a housing space for the pump (electric submersible pump) 26. The pump 26 is fixedly positioned on the upper surface of the partition plate 24. The pump 26 is a reversible pump that can reverse the inflow and outflow directions. The end opening 28a of the piping 28 connected to one inlet / outlet of the pump 26 penetrates the housing 16c and communicates with the seawater 11 surrounding the main body of the device 10. The end opening 30a of the piping 30 connected to the other inlet / outlet of the pump 26 penetrates the partition plate 24 and communicates with the bottom of the water tank 16b2. When the pump 26 is driven in one direction, it supplies seawater from around the main body of the device 10 to the water tank 16b2 via the piping 28, and when driven in the opposite direction, it drains seawater from the water tank 16b2 to the area around the main body of the device 10 via the piping 28. By adjusting the amount of seawater stored in the water tank 16b2 in this way, the buoyancy of the main body of the device 10 is adjusted and the draft is varied, and as a result the natural period of vertical movement of the main body of the device 10 in the seawater 11 is varied. An air pipe 32 is installed along the axial direction of the main body 10 of the device, connecting the water tank 16b2 to the outside air surrounding the float section 12. The lower end opening 32a of the air pipe 32 penetrates the housing 16c and communicates with the upper part of the water tank 16b2. The upper end opening 32b of the air pipe 32 communicates with the outside air surrounding the float section 12. The air pipe 32 maintains a constant air pressure inside the water tank 16b2. In Figure 1, the air pipe 32 is shown with a portion of it exposed to the outside of the main body 10 of the device, but it can also be installed with its entire length, excluding the upper end opening 32b, housed inside the main body 10 of the device. Stabilizers 34, consisting of vanes extending in the vertical direction, are arranged on the outer circumferential surfaces of the float section 12 and the weight section 16.The stabilizer 34 allows the main body 10 of the device to move up and down stably in the sea 11.

[0018] A wave height meter 36 is deployed in the sea 11 near where the main unit 10 of the device is placed, floating on the sea surface 11a. The main unit 10 of the device and the wave height meter 36 are positioned separately (i.e., their relative positions are not fixed). However, the wave height meter 36 can be attached to the main unit 10 with a rope or the like to prevent it from moving. The wave height meter 36 measures the change in the height of the sea surface 11a due to waves, for example, using a built-in acceleration sensor.

[0019] The control system of the pump 26 by the control unit 15 in Figure 2 will be explained with reference to Figure 3. The wave height data (data measuring the change in wave height in real time) measured by the wave height meter 36 is analyzed for frequency spectrum by the Fast Fourier Transform unit 40. The fundamental wave detection unit 42 detects the fundamental wave, that is, the wave component whose wave height is above a predetermined value and whose frequency of appearance within a predetermined time is determined to be relatively high compared to waves of other frequencies, from the analyzed frequency spectrum. The reason for limiting detection to waves with wave heights above a predetermined value is that even if the frequency of appearance is high, if the wave height is low, the amount of power that can be generated is small or no power can be generated at all. The detection of the fundamental wave by the fundamental wave detection unit 42 can be performed, for example, as follows: From the frequency spectrum analyzed by the Fast Fourier Transform unit 40, the frequency component of the wave with the highest wave height within a set time is detected. This operation is repeated multiple times. Each of these multiple operations detects a frequency component that is determined to have a relatively high frequency of occurrence compared to other frequency components (for example, the frequency component with the highest frequency of occurrence, the frequency component obtained by averaging frequency components with a frequency above a predetermined threshold, the frequency component at the median of the frequency component band with a frequency above a predetermined threshold, etc.) and identifies it as the fundamental wave. The draft target value calculation unit 44 determines the draft H of the device body 10 in order to match the natural period of the vertical movement of the device body 10 in the sea 11 to the period corresponding to the frequency of the detected fundamental wave (the reciprocal of the fundamental wave frequency). 0ref This is calculated as the control target value. This control target value is given by equation (1), which is derived from a simplified formula relating the draft and natural period of an object floating on the water surface. H0ref =g(Tw / 2π) 2 ...(1) Here, g: gravitational acceleration, Tw: period of the fundamental wave. The error detection unit 46 detects the draft target value H 0ref The device compares the actual draft H0 of the main unit 10 with the measured draft and detects the deviation ΔH0. The PI (proportional-integral) controller 48 drives the water supply / drainage system 50 (pump 26) to adjust the water level in the tank 16b2 so that the deviation ΔH0 becomes 0. As a result of this control, the main unit 10 resonates with the most frequently occurring waves and moves up and down significantly, resulting in a large power output from the Magnus turbine power generation unit 14. In the sea and lakes, the period of the fundamental wave does not change rapidly, so this control can be executed intermittently (a few times a day).

[0020] Here, we will explain an example of setting the weight of the solid weight 16a and the capacity of the water tank 16b2. The weight of the solid weight 16a and the capacity of the water tank 16b2 can be set based on the fluctuation range of the fundamental wave period Tw of the wave in which the Magnus wave power generation device 1 is assumed to operate, for the water body into which the main body 10 of the device is placed. That is, according to equation (1), in order to make the main body 10 of the device resonate with the fundamental wave, the draft H0 must be made shallower (the weight part 16 must be made lighter) when the fundamental wave period Tw is short, and the draft H0 must be made deeper (the weight part 16 must be made heavier) when the fundamental wave period Tw is long. Therefore, the weight of the solid weight 16a is set to a weight that can achieve the shortest period of the assumed fluctuation range of the fundamental wave period Tw when the water tank 16b2 is in its initial state where it can no longer be drained (when the water tank 16b2 can be made as light as possible). Furthermore, when the water tank 16b2 is at its maximum water capacity (when the water tank 16b2 can be made as heavy as possible), its capacity is set to achieve the longest period within the assumed fluctuation range of the fundamental wave period Tw.

[0021] The control system shown in Figure 3 above has a draft target value H 0refAlthough the draft of the apparatus main body 10 is adjusted according to the deviation ΔH0 from the actual draft H0 of the apparatus main body 10, it is difficult to directly detect the draft H0 of the apparatus main body 10 that moves up and down due to waves. Therefore, a method for adjusting the draft of the apparatus main body 10 without directly detecting the draft H0 will be described. Fig. 4 shows an example of such a method. This is to measure the amount of water flowing in and out of the water tank 16b2 (water supply amount - drainage amount), detect the measured value as a value corresponding to the water storage amount of the water tank 16b2, and adjust the draft H0 of the apparatus main body 10. In Fig. 4, the water storage amount characteristic storage unit 52 stores characteristic data (data indicating the amount of water flowing in and out of the water tank 16b2 to realize the indicated draft H0) showing the relationship between the amount of water flowing in and out of the water tank 16b2 actually measured (or obtained by calculation) and the draft H0 of the apparatus main body 10 as a look-up table or as a function. When the period Tw of the fundamental wave is detected and the draft target value H 0ref is obtained, the amount of water flowing in and out of the water tank 16b2, W 0ref to realize the draft target value H 0ref is read out as the control target value from the water storage amount characteristic storage unit 52. On the other hand, the water supply / drainage meter 54 (water storage amount detection unit) detects a value (amount of water flowing in and out) W0 obtained by adding the amount of water supplied from the pump 26 to the water tank 16b2 and subtracting the amount of water drained from the water tank 16b2 through the pump 26 as a value corresponding to the water storage amount of the water tank 16b2. The error detection unit 56 calculates the amount of water flowing in and out target value W 0refThe detected water inflow and outflow rate W0 is compared with the detected rate, and the deviation ΔW0 is detected. The pump drive unit 58 reversibly drives the pump 26 so that the deviation ΔW0 becomes 0. This control allows the main body of the device 10 to resonate with waves that occur frequently. With this method, even when the main body of the device 10 sways with the waves, causing the water in the tank 16b2 to sway and making it difficult to directly measure the amount of water stored in the tank 16b2, the amount of water stored in the tank 16b2 can be indirectly measured by measuring the water inflow and outflow rate W0 corresponding to the amount of water stored. However, in this method, which determines the water inflow and outflow rate W0 by subtracting the amount of water supplied from the amount of water drained, there is a possibility that errors may occur in the detected value compared to the actual amount of water stored in the tank 16b2 due to prolonged use. To address this, errors can be eliminated by, for example, driving the pump 26 in the drainage direction based on instructions issued automatically or based on operator operation at appropriate timings (such as at predetermined time intervals or when the amount of change in the fundamental wave component detected by the fundamental wave detection unit 42 exceeds a predetermined threshold), returning the amount of water remaining in the water tank 16b2 to its initial state where no more water can be drained, resetting the detected value of the water supply / drainage meter 54, and then resuming measurement.

[0022] Figure 5 shows another example of a method for adjusting the draft of the main body 10 of the device without directly detecting the draft H0. This method involves measuring the water level in the tank 16b2 and detecting the measured value as a value corresponding to the amount of water stored in the tank 16b2 to adjust the draft of the main body 10. In Figure 5, the water storage characteristic storage unit 60 stores characteristic data (data indicating the water level in the tank 16b2 required to achieve the specified draft H0) showing the relationship between the water level in the tank 16b2, which is actually measured (or calculated), and the draft H0 of the main body 10, as a lookup table or function. The period Tw of the fundamental wave is detected and the draft target value H 0ref When this is required, the water storage volume characteristic memory unit 60 retrieves the draft target value H 0ref The water level L of tank 16b2 achieves this. 0refThe target value is read out as the control target value. Meanwhile, the water level gauge 62 (water volume detection unit) detects the water level L0 of the water tank 16b2 as a value corresponding to the water volume of the water tank 16b2. Various types of water level gauges can be used as the water level gauge 62, such as a float type that measures the height of a float floating on the surface of the water tank 16b2, an ultrasonic type that radiates ultrasonic waves from above in the water tank 16b2 toward the surface and measures the time it takes for the waves to reflect back from the surface, and a hydraulic type that measures the water pressure at the bottom of the water tank 16b2. The error detection unit 64 reads out the target value L 0ref The detected water level L0 is compared with the detected water level, and the deviation ΔL0 is detected. The pump drive unit 66 reversibly drives the pump 26 so that the deviation ΔL0 becomes 0. This control allows the main body of the device 10 to resonate with waves that occur frequently.

[0023] As can be understood from equation (1), there is a one-to-one correspondence between the draft H0 of the main body of the device 10 and its natural frequency or natural period. Therefore, the characteristic data stored in the water storage volume characteristic memory unit 52 in Figure 4 can also be data showing the relationship between the amount of water entering and leaving the water tank 16b2 (a value corresponding to the water storage volume of the water tank 16b2) and the natural frequency or natural period of the main body of the device 10 (characteristic data showing the relationship between the amount of water entering and leaving the water tank 16b2 in order to achieve the instructed natural frequency or natural period). In that case, the target value W of the water entering and leaving is obtained from the water storage volume characteristic memory unit 52 using the frequency or period of the fundamental wave detected by the fundamental wave detection unit 42 (Figure 3). 0ref The data can be read and the control shown in Figure 4 can be performed. Similarly, the characteristic data stored in the water storage characteristic memory unit 52 in Figure 5 can also be data showing the relationship between the water level of the water tank 16b2 and the natural frequency or natural period of the main unit 10 of the device (data showing the relationship between the water level of the water tank 16b2 to realize the instructed natural frequency or natural period). In that case, the water level target value L can be read from the water storage characteristic memory unit 52 using the frequency or period of the fundamental wave detected by the fundamental wave detection unit 42 (Figure 3). 0ref The data can be read and the control shown in Figure 4 can be performed.

[0024] In the above embodiment, the weight section had a solid weight placed on the lower side and a water tank on the upper side, but the relative positions of the two can also be reversed, with the solid weight on the upper side and the water tank on the lower side. It is also possible to arrange the solid weight and the water tank concentrically (for example, placing an annular solid weight made of a metal block or the like on the outer circumference and using the space on the inner circumference as the water tank, or conversely, placing the solid weight in the center and using the space on the outer circumference as the water tank). Furthermore, in the above embodiment, the pump was placed in the space above the water tank, but instead, the pump can be placed submerged in the water of the water tank or in a space provided below the water tank. In addition, in the above embodiment, the wave height change detection unit was configured by floating a wave height meter equipped with an acceleration sensor on the sea surface, but instead, the wave height change detection unit can be configured by installing a radar wave height meter on a support or base that is installed on the coast or fixed to the seabed and protruding above the sea surface. [Explanation of symbols]

[0025] 1...Magnus wave power generation device, 10...Device body, 10a...Central axis of the device body, 11...Underwater, 11a...Sea surface, 11b...Wave, 12...Float section, 12a...Housing, 12b...Air chamber, 13...Seabed, 14...Magnus turbine power generation section, 15...Control section, 16...Weight section, 16a...Solid weight, 16b...Cavity, 16b1...Cavity (pump housing space), 16b2...Cavity (water tank), 16c...Housing, 17...Mooring wire, 18...Magnus turbine, 19...Anchor, 20...Power generation unit (with built-in generator), 21...Cable, 22...Reducer and diffuser, 22b...Cavity, 22c,22d...Opening, 24...Partition plate, 26...Pump (electric (Water pump), 28, 30… Piping for submersible pump, 28a, 30a… End openings of submersible pump piping, 32… Air pipe, 32a… Lower end opening of air pipe, 32b… Upper end opening of air pipe, 34… Stabilizer, 36… Wave height meter (wave height change detection unit), 40… Fast Fourier transform unit, 42… Fundamental wave detection unit, 44… Draft target value calculation unit, 46… Error detection unit, 48… PI controller, 50… Water supply / drainage system, 52… Water storage volume characteristic memory unit, 54… Water supply / drainage meter (water storage volume detection unit), 56… Error detection unit, 58… Pump drive unit, 60… Water storage volume characteristic memory unit, 62… Water level meter (water storage volume detection unit), 64… Error detection unit, 66… Pump drive unit

Claims

1. The device is constructed as an integrated structure in which a float section, a Magnus turbine power generation section, and a weight section are arranged vertically and interconnected from top to bottom. The Magnus turbine power generation section comprises a Magnus turbine and generator driven by wave power utilizing the Magnus effect, and the weight section comprises a solid weight and a water tank. The device body floats in the water with at least the upper part of the float section above the water surface when submerged in water. A pump mounted within the main body of the device, which, when the main body of the device is submerged in water, supplies water from around the main body of the device to the water tank or drains water from the water tank to the area around the main body of the device, thereby changing the amount of water contained in the water tank, and thereby changing the natural period of the vertical movement of the main body of the device in water; A wave height change detection unit, which is disposed separately from the main body of the device and detects changes in the water surface height around the main body of the device, which is submerged in water, due to waves, A control unit that, based on the wave height change detection unit, determines that a wave component whose wave height is above a predetermined value and whose frequency of appearance within a predetermined time is relatively high compared to waves of other periods is the fundamental wave, detects the period or frequency of the fundamental wave, and controls the pump to drive the pump so that the natural period of the main body of the device follows the detected period or frequency of the fundamental wave. A Magnus wave power generation device.

2. The control unit comprises a water volume characteristic storage unit that stores the characteristics of the water volume of the water tank or a value equivalent to the water volume, which realizes the natural period of the main body of the device corresponding to the period or frequency of the detected fundamental wave, and a water volume detection unit that detects the water volume of the water tank or a value equivalent to the water volume. The control unit reads the amount of water stored in the tank or a value equivalent to the amount of water stored, corresponding to the period or frequency of the detected fundamental wave, from the water storage amount characteristic storage unit, and controls the pump to drive so that the amount of water stored in the tank or a value equivalent to the amount of water stored, detected by the water storage amount detection unit, follows the amount of water stored or a value equivalent to the amount of water stored, read from the water storage amount characteristic storage unit. The Magnus wave power generation apparatus according to claim 1.

3. The aforementioned pump is reversibly driven to supply water to the water tank and drain water from the water tank. The water storage volume detection unit detects a value equivalent to the water storage volume of the tank by adding the amount of water supplied from the pump to the tank and subtracting the amount of water drained from the tank through the pump. The Magnus wave power generation apparatus according to claim 2.

4. The control unit drives the pump in the draining direction based on a predetermined instruction to return the water tank to its initial state where no more water can be drained, and also performs control to reset the detected value of the water level detection unit. The Magnus wave power generation apparatus according to claim 3.

5. The Magnus wave power generation apparatus according to claim 1, wherein the pump is located in the water tank or in a space adjacent to the water tank, below the Magnus turbine power generation unit.

6. The Magnus wave power generation apparatus according to claim 1, wherein the wave height change detection unit comprises a wave height meter positioned so as to float on the water surface near where the main body of the apparatus is immersed.

7. The Magnus wave power generation apparatus according to claim 1, wherein the control unit controls the intermittent operation of the pump during the day.

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