JP2005069212A - Floating body type wave force power generator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem of the conventional wave force power generator having high efficiency that the ocean civil work cost is very high to obstruct the supply of practical and inexpensive wave generated power, and in the floating body system wave force power generator not requiring ocean civil work cost, the efficient power obtaining from wave force is obstructed by rocking of the floating body due to wave to be far from the efficiency of practical use. <P>SOLUTION: In this floating body type wave force power generator, a pendulous type wave force power generating means is provided in a water chamber having an opening for receiving advancing wave from the front, and on the other hand, a vertical plate and a horizontal plate are provided in positions with a phase lag of 180° of the wave in positions downstream 1/2 wavelength from the pendulous position, and firmly fixed to the body of a hull including the water chamber. In addition, the vertical load of seawater applied to the water chamber is conformable to the buoyancy of the hull. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a high-efficiency floating-type wave power generation apparatus that uses a wave power of natural energy on the sea away from a coast as a driving force.

  Environmental measures symbolized by the depletion of energy resources and global warming are widely recognized as important issues in the near future, and natural energy power generation using wind power and solar energy is becoming popular. Among them, the ocean wave energy, which is said to have a surplus of 2.7 billion kilowatts, has a severe prospect of practical use, and only a small number of demonstration plants have been constructed. Research on the use of ocean wave energy has been ongoing, but the fact that it is not easy to establish the economics of wave power generation is the biggest bottleneck in practical application.

  There are actual examples of the wave power generation ship `` Kaimei '' which is the oldest demonstration device and `` Mighty Whale '' recently established in Minami-cho, Mie, as a type that generates power on the ocean with a power generator mounted on the floating body, The efficiency has been reduced by the swinging of the floating body, and a large amount of cost has been required for the countermeasure. In reality, it remains a low-efficiency device that is far from practical use.

On the other hand, as a type of power generation on the coast by installing a power generation device on a fixed object such as a breakwater, the present inventors installed a demonstration device at Muroran Port, and a water column vibration type that has many examples overseas There is an example of a wave power generator. Coastal low-energy waves are the target of power sources, but efficiency is good enough to be put to practical use, but facilities such as breakwaters are extremely expensive. Reduction cannot be expected.
U.S. Pat. No. 4,580,400 Japanese Patent No. 2539742 Design Engineering Vol. 36, no. 1 “Prospects and Challenges for Practical Use of Wave Power Generation”

  The first problem to be solved by the present invention is to realize a low-cost floating-type wave power generator with a small and extremely simple structure. As a result of effectively suppressing by itself, it is to obtain a floating wave power generation device that can significantly increase the energy acquisition efficiency from wave power, and the third problem is due to the synergistic effect by solving these two problems, It is to provide the world's first truly practical wave power generator that can reach an economical practical level.

  In the present invention, the basis of the wave power generator is selected as the floating body type. In this type of wave power generation device, it is important how to effectively prevent a decrease in power generation efficiency due to floating body swinging. Floating body swing is an example of a forced vibration phenomenon caused by wave forces that are external forces. Therefore, if the parameters related to this phenomenon are known, the phenomenon can be predicted immediately. In the present invention, first, in order to suppress the floating body swinging motion, a new technical idea of a phase control method of wave force acting on the floating body is introduced. The phase delay that is effective for swing control is 120 to 180 °, and the principle that a wave force with a phase delay of at least 90 ° acts positively on floating body swing and the power generation output is also increased is known. However, no concrete means of realization was found. The present invention provides a water chamber for receiving waves in a floating body and a basic structure for receiving wave force by a pendulum plate that swings in the water chamber, and is 180 ° at a distance of ½ wavelength from the attachment position of the pendulum plate. This was achieved by firmly fixing the vertical plate with a sufficient area at the position where the phase was delayed and the horizontal plate fixed to the lower surface. This is a very simple structure that only fixes the plate. Therefore, no conventional expensive dampers that limit movement are used.

  According to the present invention, the floating body is provided with a water chamber, and power is generated by waves in the water chamber. Therefore, the vibration parameters are manipulated by selecting the shape and size of the water chamber, and the floating body is effectively swung by an anti-phase wave force. It is possible to control. Since the pendulum type wave power generation device and the water column vibration type wave power generation device are of this type, adopting the method of the present invention for floating body swing control has a great effect on reducing the unit price of power generation. Conventionally, the construction cost of breakwaters and caisson offshore civil engineering, which accounted for 70% of the cost, is unnecessary, and the construction cost of the entire wave power generator can be greatly reduced. Next, the problem of efficiency reduction due to swinging of the floating wave power generation system can not only be solved effectively by extremely simple means, but the wave power that has caused floating body swinging is actively utilized to improve the power generation output. A significant increase in output is obtained. Furthermore, the multi-point tension mooring method required in the conventional water column vibration type wave power generation apparatus is unnecessary, and the loose one-point mooring method is sufficient, so the mooring cost is greatly reduced. As a result, the above-mentioned effects work synergistically to enable an effective reduction in unit price of power generation that can withstand practical use.

  In addition, the floating wave power generation device of the present invention has an effect that the installation location can be changed. If the installation location is selected and moved depending on the situation, the effective wave power generation device can be operated, and if a typhoon strikes, it can be evacuated to a safe location. In addition, since it is possible to reduce the size and increase the output, it can be used for wide-area applications such as pumping deep ocean water, water circulation in aquaculture water areas, offshore plant for ice production for hydrogen production and eco-ice for cooling. If it is possible to tow the floating-type wave power generation device of the present invention, an offshore plant as a work ship serving as a mother ship, if it is possible to supply almost the total amount of power generated, it has become a problem with mighty whales, It is also possible to avoid the problem that power transmission means to the ground is difficult. In addition, since the present invention is a one-point mooring system, it can naturally cope with changes in the direction of waves. Therefore, there is an effect that the efficiency reduction due to the change in wind direction is eliminated.

BEST MODE FOR CARRYING OUT THE INVENTION

  In the best mode for carrying out the present invention, the above-described effect cannot be expected unless it is a rational form based on the change of the wave motion form on the sea due to the phase shown in FIG. Therefore, first, the explanation will be given with reference to FIG. 1 for explaining the motion form for each phase by the motion vector change of the wavefront. The phase diagrams from (1) to (5) in FIG. 1 show the change in the wavefront of each quarter cycle of a sine wave traveling from the left hand to the right with respect to the seabed 1. This wavefront shows a phase change every 90 °. Point A shown at the left end of the phase diagram of (1) propagates through the sea surface by a distance of 1/4 wavelength on the diagrams of (2), (3), (4), and (5). A wave reaching the right end of the phase diagram of ▼ is generated. The wave from the phase diagram (1) to the phase diagram (5) corresponds to exactly one wavelength. In wave theory, an object floating on the water surface does not move by one wavelength distance during this period, but seawater molecules that repeat a substantially circular motion propagate circular motion with a time delay from upstream to downstream. In addition, the wave propagates so that the wavefront apparently moves downstream. The sea surface on which the wave power generation device of the present invention is installed is planned to be a shallow sea area with a depth of about 10 m. In this case, the motion of water molecules on the sea surface is an elliptical motion that collapses in the vertical direction. The planned pendulum installation position of the present invention is a position corresponding to point A in the phase diagram (2) as indicated by the broken line, and the vertical plate installation position is at point A in the phase diagram (4). Corresponding position. The motion vector of the wave front at both positions is represented by a curve along the ellipse. In the phase diagram of (1), the wave is at the apex at the planned position of the pendulum, and the motion and wave force can be expressed with a large right motion vector, and the large left motion vector that is the valley bottom at the planned position of the vertical plate. Can express wave power. Both of these waves are 180 ° out of phase, and wave force in the opposite direction acts. Further, in the state of phase diagram (2) after the lapse of 1/4 cycle, the wave force in the downward arrow direction is at point A of the predicted pendulum position, and the wave force in the upward arrow direction is shown at the vertical plate planned position. It becomes. Furthermore, in the phase diagram of (3), which is the 2/4 cycle time after 1/4 cycle, the planned pendulum position and the planned vertical plate position are symmetrical with the phase diagram state of (1). The position is at the bottom of the valley and the top of the wave, and the wave force is in the opposite direction to that in the phase diagram (1). Further, at the time of 3/4 cycle after the lapse of 1/4 cycle, as shown in the phase diagram of (4), the wave force is upward at the pendulum position but downward at the vertical plate position of point A. Further, at the time of the phase diagram (5) after a quarter cycle, the state returns to the state shown in the first phase diagram (1), and the wave motion is repeated periodically.

  In FIG. 2, the phase diagrams from (1) to (5) show the state of the water surface change inside the wave power generation device of the present invention. expressing. In FIG. 2, unlike the phase diagram shown in FIG. 1, the surrounding waves are not necessarily the same in the interior of the water chamber where the pendulum is installed or the rear of the vertical plate, but with partially different water surface fluctuations. Yes. The difference between the two can be clearly understood by comparing the phase diagrams with the same numbers (1) to (5) indicating the same phase. Especially in a closed water chamber that is surrounded by a pendulum and a water chamber at the back of the water chamber and independent of the surrounding waves, a standing wave is generated due to the swinging of the pendulum, and the water surface repeats a substantially constant vibration. Yes.

  The basic configuration of the floating wave power generation device of the present invention will be described with reference to the phase diagram (1) in FIG. The hull 2 constituting the main body of the floating wave power generation device moored on the seabed 1 with a mooring rope 3 has a water chamber 4 opened on the left side of the hull 2 so as to be swingable inside the water chamber 4. A pendulum plate 6 pivoted on the top is provided. A bottom plate 11 is provided at the bottom of the water chamber 4, and a closed water chamber 10 provided behind the water chamber 4 constitutes a water chamber which is surrounded by the pendulum plate 6 and the rear wall 5 and is substantially closed. It is inside the closed water chamber 10 that a standing wave is generated by the swinging of the pendulum plate 6. The most characteristic vertical plate 8 and horizontal plate 9 in the present invention are firmly fixed to the hull 2 by the connecting plate 7 at a position where a phase difference of 180 ° occurs behind the pendulum plate 6 by a half wavelength. ing. In order to absorb the wave force and convert it into electric power, the pendulum motion is converted into a unidirectional rotational motion by a hydraulic device and the generator is rotated. The technical details are described above. See literature. The buoyancy of the hull 2 is provided by a side plate having an appropriate thickness, which will be described in detail later.

  The change of the wavefront in each phase diagram of FIG. 2 will be described. First, the influence of the pendulum plate 6 will be described. When the water flow is directed from the left hand side into the water chamber 4, the water flow is decelerated on the surface of the pendulum plate 6 and the pressure is increased. This causes a rise in the water level, but if the pendulum plate 6 swings at a speed that does not change much from the speed of the water flow, the rise in the water level is slight. Conversely, when the water flow moves away from the pendulum plate 6, the water flow accelerates on the surface of the pendulum plate 6 and the water pressure decreases. This lowers the water level. However, if the relative speed with respect to the pendulum plate 6 is reduced, the change in the water level is reduced as described above. When the pendulum plate 6 is swinging in the right direction as a result of the waves moving in the closed water chamber 10, the water surface rises in conjunction with the volume of the closed water chamber 10 being reduced. Occurs, and the water level is lowered in conjunction with the expansion of the volume of the closed water chamber 10 when it is swinging in the opposite left direction. Due to the movements of the water surfaces, counterclockwise and clockwise rotational moments M are generated alternately on the shaft that supports the pendulum plate 6. In the phase diagram {circle around (1)}, the pendulum plate 6 is in a state where the pendulum plate 6 is swinging downward in the vertical direction and rightward, but the wave introduced into the water chamber 4 is not in the pendulum plate 6. While reaching its peak in position, the water surface of the closed water chamber 10 is about to rise due to the swinging of the pendulum plate 6 and is the lower water level. In the state shown by the phase diagram {circle around (2)} after the lapse of a quarter cycle, the pendulum plate 6 swings to the rightmost position and is the moment when it is going to change direction to the left. A large clockwise moment is required to change the direction, but the water surface of the closed water chamber 10 is the highest, and the water surface of the water chamber 4 is low. Trying to move downwards. Therefore, the difference in water level between the two water chambers is about to increase. Further, when the state of the phase diagram of (3) after the lapse of a quarter cycle is reached, the pendulum plate 6 is in the middle of the swinging motion directed vertically downward and toward the left at the maximum speed. Although the water surface near 6 is the lowest valley bottom, the water surface of the closed water chamber 10 is still at a medium height, and the water surface is being further lowered. Further, the state of the phase diagram (4) after the lapse of ¼ period is the moment when the pendulum plate 6 reaches the leftmost position and this time it is going to change direction to the right. The seawater that is about to flow into the water chamber 4 that opens from the left direction has the water level rising along the pendulum plate 6 as a result of the speed of the pendulum plate 6 becoming zero when the direction of the pendulum plate 6 is changed. The moment is increased. On the other hand, the water surface inside the closed water chamber 10 is at the lowest level, and a water surface difference between the two water chambers causes a large counterclockwise moment to the right. As a result, when the pendulum plate 6 starts to swing rightward again and reaches the state of the phase diagram (5) after a quarter cycle, the state returns to the phase diagram state (1). Continue exercise.

  In order to convert the wave force generated in the pendulum plate 6 described above into generated power, a reaction force of the moment M must be applied to the hull 2. In the case of a device that is fixed on the ground, the pressure of the ground is responsible for this reaction force, but in the floating wave power generator floating on the sea, the reaction force necessary for this power generation is reasonably generated. Ingenuity is required, and the present invention enables high-efficiency wave power generation by making good use of the properties of waves. That is, in the phase diagram (1) in FIG. 2, the pendulum plate 6 receives a rightward wave force on the top of the wave, but the position of the vertical plate 8 separated by ½ wavelength is 180 ° out of phase. It is in a state where it receives the wave power of the wave that became the bottom of the valley. The sea water on the left side of the vertical plate 8 quickly flows to the left in the phase of the wave that forms the bottom of the valley, and the water surface descends, but the sea water on the right side of the vertical plate 8 is blocked by the vertical plate 8 and left Unable to move in the direction, the water pressure rises and the water level rises. As a result, it is considered that the vertical plate 8 receives a large leftward force from the wave force that is greater than the rightward force that the pendulum plate 6 receives due to the wave force. If a large force is applied to the vertical plate 8, it is considered that the wave force that can be used for power generation is positively increased. Therefore, it is considered that it is advantageous to make the area of the vertical plate 8 sufficiently large. Next, in the state of the phase diagram of (2), the pendulum plate 6 changes direction to the left in response to the moment M in the clockwise direction, but the wave front of the vertical plate 8 receives an upward wave force due to the upward flow, A horizontal plate 9 fixed to the bottom of the vertical plate 8 applies a counterclockwise moment to the hull 2 by wave force. Furthermore, in the state of the phase diagram (3) after the lapse of 1/4 cycle, the pendulum plate 6 is in the middle of the movement in the vertical direction and toward the left, and receives a moment in the clockwise direction. A vertical plate 8 that is 180 ° out of phase with a wavelength separation is located at the top of the wave and receives a rightward wave force. Here again, the vertical plate 8 serves to prevent the wavefront from moving to the right, so that the left sea level rises from the surroundings and the right sea level is lower than the surroundings. Also in this case, it is considered that when the vertical plate 8 applies a large force to the hull 2, there is an effect of increasing the power generation energy received from the wave force. Further, when the state progresses by ¼ period and becomes the state of the phase diagram of (4), the pendulum plate 6 is time to change the direction from the left direction to the right direction, and at the position of the vertical plate 8 that is 180 degrees behind the phase, The horizontal plate 9 receives a downward wave force. The horizontal plate 9 applies a clockwise moment to the hull 2 against the counterclockwise moment M received by the pendulum plate 6. Further, when the state of the phase diagram (5) after the ¼ cycle has elapsed, the state returns to the state of the first phase diagram (1), and these circulations are sequentially repeated.

  The operation of the vertical plate 8 and the horizontal plate 9 fixed thereto has been described. These are involved in the surge motion and pitching motion of the hull 2. That is, the vertical plate 8 effectively prevents surge motion that causes the hull 2 to swing in the front-rear direction, and the horizontal plate 9 greatly contributes to prevention of pitching motion. Another harmful hull motion associated with floating rocking is the heave motion that moves up and down in the vertical direction. This last heave motion prevention will be described below. In each of the phase diagrams (1) to (4) in FIG. 2, the seawater in the water chamber 4 applies a water pressure that is a vertical pressure to the bottom plate 11. This water pressure is a vertical load with respect to the hull 2. Therefore, when the top of the wave penetrates deeply into the water chamber 4, the vertical load also becomes maximum, and at the same time, the vertical load and the buoyancy cancel each other almost in synchronization with the maximum value of the buoyancy applied to the hull 2. The action will work. As a condition for this purpose, it is necessary that the width dimension of the water chamber 4 and the width dimension of the side plates on both sides of the hull be matched, but it is difficult to prevent this heave motion by optimizing the design dimensions. Means can be obtained. In the model experiment device, a weight is introduced into the hull for optimal adjustment. Therefore, this heave motion countermeasure can be realized with certainty.

  Finally, the structure of the hull 2 of the floating wave power generation apparatus of the present invention is shown in FIG. The width of the hull 2 is 40 cm, the length is 80 cm, and the height is 37 cm. The opening of the water chamber 4 is open at the left end, and a water chamber having a constant width of 22 cm and a depth of 50 cm to the rear wall 5 is formed on the water chamber side, and this is formed into a pendulum plate 6. The water chamber 4 on the open side and the closed water chamber 10 are separated. The hull 2 has a bottom plate 11, side plates 12 and 12 on both sides, and a rear wall 5. It is the thickness of the side plate 12 that gives the hull 2 the necessary buoyancy. In the 1/25 model, this thickness dimension is 9 cm. A vertical plate 8 and a horizontal plate 9 fixed to the vertical plate 8 which are characteristic components of the apparatus of the present invention are firmly fixed to the hull 2 by connecting plates 7 and 7. The vertical width of the vertical plate 8 is 42 cm, and the height is 37 cm, which is the same as the hull 2. The distance from the attachment position of the pendulum plate 6 to the vertical plate 8 is 95 cm. When the direction of the wave changes, the connecting plate 7 can be expected to receive a wave force and to make the opening of the water chamber 4 face the front of the wave.

  Using the 1/25 model shown in FIG. 3, a model wave was generated by generating a regular wave having a wavelength of 1.9 m in a water tank. In the experiment, a damper was attached to the pendulum, and the change in energy acquisition efficiency was measured by changing the load condition in the swing motion of the pendulum. Even with the conventional caisson-type pendulum wave power generator, the highest frequency efficiency was achieved by impedance matching by optimizing the natural frequency of the swinging motion of the pendulum and the load. The load was changed under conditions that deviated from the optimum conditions. The data exceeded the caisson-type efficiency, and the results were evaluated as equal or better. We also observed heave, surge, and pitch motions of the hull, but all the motions were small and confirmed to be minute motions with a phase lag of about 180 ° with respect to the wave at the pendulum position. The energy conversion efficiency 65 to 86% at this time is exactly champion data. It is considered that better data can be obtained if the impedance matching is optimized.

  The size of the closed water chamber of the present invention is considerably shorter than the theoretical size of the standing wave in the conventional caisson type wave power generation. It is about 63% of the dimension corresponding to a quarter wavelength of waves at sea. The first reason is that in the water chamber where the water depth is shallower than the wave at sea, the wavelength of the wave is shortened. The second reason is that, based on experience so far, it is not an experimental wave called a regular wave, but a natural wave with an indefinite wave wavelength and period has a small decrease in efficiency for a wave with a long wavelength, but the wavelength is small. This is because the efficiency is significantly reduced with respect to a short wave, and it is considered that an apparatus adapted to a wave with a short wavelength may be used in order to prevent overall efficiency reduction. As a result, the length of the hull planned to be constructed by welding iron plates can be considerably shortened, which is advantageous for cost reduction.

  According to experience, the rate of decrease in the efficiency of an actual wave power generator targeting natural waves is about 65% with respect to experimental data in a water tank using regular waves. The energy acquisition efficiency of the actual machine based on this data can be estimated to be approximately 55%.

  Finally, specifications outside the design dimensions of the practical machine will be described as the best embodiment for carrying out the invention. Water depth of the target sea surface: 10 m, wave height: 2 m, wave period: 6 seconds, wavelength: 48 m, incident wave power per 10 m of water chamber opening width: 250 kW (in the case of regular waves), generator capacity: 150 kW, total weight: 140 tons

  FIG. 5 is a phase diagram of five waves showing wave progress and sea level change every quarter period of the wave.   FIG. 5 is a phase diagram for every ¼ period as in FIG. 1, showing changes in the water level in the water chamber and changes in the sea level in the cross section near the water chamber and the vertical plate of the floating wave power generator of the present invention.   It is a perspective view of 1/25 model of the floating type wave power generator of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Seabed 2 Hull as floating body provided with wave power generation device of present invention 3 Hull mooring rope 4 Water chamber 5 having opening for receiving ocean wave 5 Water chamber rear wall 6 Pendulum plate 7 Vertical plate fixed to hull Connecting plate 8 Vertical plate 9 Horizontal plate 10 fixed to the lower part of the vertical plate Closed water chamber 11 Bottom plate 12 Side plate M Rotational moment applied to the pendulum plate T Wave period

Claims (4)

  A water chamber having one surface open to the waves traveling on the sea is provided, and this water chamber has a hull, a bottom plate, and a rear wall opposite to the opening as a common component, and a pair of both sides of the water chamber. The hull is constructed with a side plate having a predetermined width, and a wave force acquisition means such as a pendulum plate is provided in the water chamber, while waves with vertical movement of the sea surface enter the water chamber. However, the width of the side plate is determined so that the buoyancy fluctuation applied to the hull by the synchronized wave and the vertical load fluctuation due to seawater pressure fluctuation applied to the bottom plate in the water chamber are the same level. Floating wave power generator   A water chamber having one surface open to the waves traveling on the sea is provided, and this water chamber has a hull, a bottom plate, and a rear wall opposite to the opening as a common component, and a pair of both sides of the water chamber. The hull is configured with a side plate having a predetermined width, and a pendulum plate as a wave force acquisition means is provided in the water chamber, while waves with vertical movement of the sea surface enter the water chamber. In addition to the fact that the width of the side plate is determined so that the buoyancy fluctuation applied to the hull by the synchronized wave and the vertical load fluctuation due to seawater pressure fluctuation applied to the bottom plate in the water chamber are the same level, the pendulum plate Floating-type wave power generator in which a vertical plate having a sufficient area is firmly fixed to the hull by a connecting plate at a downstream position that is 1/2 wavelength away from the mounting position   The floating wave power generator according to claim 2, wherein a horizontal plate is fixed to a bottom portion of the vertical plate.   The mooring of the hull is a loose mooring system with a single mooring rope, and even if the wave traveling direction changes due to the change in wind direction, it receives the wave force that always keeps the water chamber opening to the front of the traveling wave The floating body wave power generator according to claim 2 or 3, wherein the plate firmly connects the hull and the vertical plate.

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