JP7197896B2 - Tidal power generation system and mooring equipment - Google Patents

Description

Application of Article 30, Paragraph 2 of the Patent Act "Research and development of a low-cost submersible tidal current power generation system applicable to low-velocity tidal current areas" Surugadai Campus Building 1 (1-8-14 Kanda Surugadai, Chiyoda-ku, Tokyo) August 7, 2018

TECHNICAL FIELD The present invention relates to a tidal current power generation system that generates power using a tidal current and a mooring device therefor.

A tidal current power generation system is known that generates electricity by the flow of seawater at high tide and ebb tide, ie, tidal current. A tidal current power generation system has a turbine placed in seawater, and the turbine is rotated by the tidal current to rotate a generator to generate power. The generators are moored, for example, by cables extending from the sea bed.

JP-A-55-72665 Japanese Patent No. 4642747 Japanese Patent No. 6150046

In a tidal current power generation system that generates power using a floating power generator connected to mooring lines, it is necessary to change the direction of the power generator according to changes in the direction of the tidal current.

In Patent Document 1, the center of gravity and the center of buoyancy of a floating body equipped with a generator are made to coincide on the center line of the floating body, and a mooring point 4 is provided on a horizontal line that passes through this point and is perpendicular to the center line. , to change the area moment of inertia of the floating body before and after the mooring point.

In addition, if the center of gravity, the center of buoyancy, and the mooring point 4 all coincide, the posture of the floating body cannot be uniquely determined at the time of the tidal current when there is no tidal current. 2), the mooring point 4 is shifted to the inlet side of the floating body.

However, when the mooring point is shifted as described above, the buoyant force of the floating body is greater than the gravity force. Inability to keep the body horizontal.

WO 2005/010001 shows that the turbine 3 with turbine blades 5 has a mooring point 9 in order to be able to swivel, and that the center of gravity and the center of buoyancy of the turbine are spaced apart from each other.

Although the positional relationship between the center of gravity and the center of buoyancy is not specified in Patent Document 2, in order to achieve posture 8 in FIG. can do.

However, with the positional relationship as described above, the moment of buoyancy with respect to the mooring point is greater than the moment of gravity, and the turbine cannot be held horizontally when a tidal current occurs.

Further, in a tidal current power generation system in which a floating power generator connected to a mooring line generates power, as the tidal current increases and the force that the power generator receives from the tidal current increases, the sinking of the power generator increases. If the sinking of the power generation device becomes large, the power generation device may come into contact with the seabed and be damaged.

Therefore, in Patent Document 3, the mooring angle detection means 9 for detecting the angle change of the mooring rope 7 due to the sinking of the power generator is provided. preferably not.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to reduce the possibility of a power generation device coming into contact with the seabed even when the tidal current in a tidal current power generation system becomes large.

To achieve the above object, the present invention provides a tidal current power generation system in which a turbine rotated by the tidal current, a generator for generating electricity by the rotation of the turbine, and the turbine and the generator are held inside and held outside. A tidal current power generation system comprising: a power generator including a casing having a mooring point formed thereon; and a mooring line anchored to the seabed, extending from the seabed to the casing and anchored to the mooring point, wherein , the casing has an annular shape penetrating toward a first opening and a second opening, the second opening being formed in a funnel shape larger than the first opening, and the anchor point being the second opening; the center of buoyancy of the power generator is closer to the second opening than the mooring point, the center of gravity of the power generator is closer to the second opening than the center of buoyancy, the center of buoyancy and the mooring point multiplied by the buoyancy of the power generator is greater than or equal to the product of the distance between the center of gravity and the mooring point multiplied by the gravity of the power generator .

ADVANTAGE OF THE INVENTION According to this invention, even when a tidal current becomes large in a tidal current power generation system, a possibility that a power generation apparatus will contact the seabed can be reduced.

1 is a side view of a first embodiment of a tidal power generation system according to the present invention; FIG. 1 is a top view of a first embodiment of a tidal power generation system according to the present invention; FIG. BRIEF DESCRIPTION OF THE DRAWINGS It is a side view of the electric power generating apparatus in 1st Embodiment of the tidal current power generation system which concerns on this invention. 1 is a front view of a power generator in a first embodiment of a tidal current power generation system according to the present invention; FIG. 1 is a rear view of a power generator in a first embodiment of a tidal current power generation system according to the present invention; FIG. 1 is a side view showing the posture of the first embodiment of the tidal current power generation system according to the present invention at the time of intermittent flow; FIG. 1 is a side view showing the posture of the first embodiment of the tidal current power generation system according to the present invention when the tidal current is large; FIG. FIG. 2 is a side view showing the attitude of the first embodiment of the tidal current power generation system according to the present invention when the tidal current is even greater; FIG. 2 is a side view of a second embodiment of a tidal current power generation system according to the present invention; Fig. 3 is a side view of a third embodiment of a tidal power generation system according to the present invention; FIG. 3 is a top view of a third embodiment of a tidal current power generation system according to the present invention; FIG. 11 is a side view showing the posture of the third embodiment of the tidal current power generation system according to the present invention at the time of intermittent flow; FIG. 11 is a side view showing the attitude of the third embodiment of the tidal current power generation system according to the present invention when the tidal current is larger; FIG. 11 is a side view showing the attitude of the third embodiment of the tidal current power generation system according to the present invention when the tidal current is even greater.

Several embodiments of a tidal power generation system according to the present invention will be described with reference to the drawings. These embodiments are merely examples, and the present invention is not limited to these. The same reference numerals are given to the same or similar configurations, and redundant explanations are omitted.

[First embodiment]
FIG. 1 is a side view of a first embodiment of a tidal power generation system according to the present invention. FIG. 2 is a top view of the tidal power generation system of this embodiment. FIG. 3 is a side view of the power generator according to this embodiment. FIG. 4 is a front view of the power generator according to this embodiment. FIG. 5 is a rear view of the power generator according to this embodiment.

The tidal power generation system 10 of the present embodiment generates power using tidal currents. Here, the tidal current is the flow of sea water (seawater), and includes the flow of seawater that periodically changes direction due to the ebb and flow of the tide. For example, seawater generally flows in the direction of arrow 91 during high tide and in the direction of arrow 92 during low tide. FIG. 1 shows the situation when the direction of the tidal current is in the direction of arrow 92 .

The tidal current power generation system 10 has a power generator 20 , a mooring cable 30 and an intermediate weight 40 . The power generator 20 has a turbine 27 , a generator 26 and a casing 23 . The casing 23 is formed in an annular shape penetrating from the first opening 21 toward the second opening 22 . Both the first opening 21 and the second opening 22 of the casing 23 are circular. A second opening 22 of the casing 23 is larger than the first opening 21 . The casing 23 is funnel-shaped. A pair of horizontal wings 24 protrude horizontally from the outer surface of the casing 23 .

The mooring line 30 is anchored to the seabed 51 with anchors 50 . A mooring line 30 extends from the sea bed 51 to the casing 23 . The end of the mooring line 30 opposite the seabed 51 is attached to the casing 23 . The end of the mooring cable 30 on the casing 23 side is branched into two, each of which is attached to the mooring point 25 of the horizontal wing 24 of the casing 23 . It is preferable that the attachment portion of the mooring cable 30 to the horizontal wings 24 be rotatable.

Casing 23 is made of resin, for example. The casing 23 may be made of steel with a watertight hollow portion formed therein. Turbine 27 is made of resin, for example. The turbine may be made of steel or other sheet metal. The generator 26 is coupled to the rotating shaft of the turbine 27 and generates electricity by rotating the turbine 27 . A cable (not shown) is connected to the generator 26, and the generated electricity is connected to a land transmission line, for example. The power generator 20 is formed so that the buoyancy in seawater as a whole is greater than the gravity.

The mooring cable 30 is, for example, a bundle of metal wires. Anchor 50 rotatably supports mooring cable 30, for example.

The intermediate weight 40 is made of steel, for example, and its gravity is greater than its buoyancy. The intermediate weight 40 is fixed to, for example, the center of the mooring cable 30 . The total buoyant force exerted on the mooring cable 30 , the intermediate weight 40 and the power generator 20 is greater than the gravitational force exerted on the mooring cable 30 , the intermediate weight 40 and the power generator 20 .

FIG. 6 is a side view showing the posture of the tidal current power generation system according to the present embodiment when the current is intermittent.

At the time of rest, that is, when there is no tidal current or the magnitude of the tidal current is less than a certain threshold, the total buoyancy received by the mooring rope 30, the intermediate weight 40, and the power generator 20 is and the power generation device 20, the second opening 22 of the casing 23 faces upward and stands still. If the mooring line 30 is long enough, the casing 23 floats on the sea surface.

FIG. 7 is a side view showing an example of the attitude of the tidal power generation system of the present embodiment when a tidal current occurs.

When the magnitude of the tidal current exceeds a certain threshold, the power generator 20 is flowed in the direction of arrow 92, as shown in FIG. A clockwise moment 922 acts on the mooring point 25 when the angle θ between the axis of the generator 20 and the current is positive (θ>0 degrees). When θ=0 degrees, if the casing 23 is axially symmetrical about the axis extending from the first opening 21 to the second opening 22 as in the present embodiment, the moment 922 becomes 0 due to the symmetry. (zero).

As shown in FIG. 3, the mooring point 25 is provided relatively close to the first opening 21 . A center of buoyancy 201 of the power generator 20 is positioned closer to the second opening 22 than the mooring point 25 . In other words, the power generation device 20 is formed such that the center of buoyancy 201 is positioned between the mooring point 25 and the second opening 22 . The center of gravity 202 of the power generation device 20 is positioned closer to the second opening 22 than the center of buoyancy 201 . In other words, the power generation device 20 is formed such that its center of gravity 202 is positioned between the center of buoyancy 201 and the second opening 22 .

If the distance between the mooring point 25 and the center of buoyancy 201 is a, and the distance between the mooring point 25 and the center of gravity 202 is b,
a x (buoyancy of power generator) = b x (gravitational force of power generator)
When , the moment caused by the buoyancy of the generator 20 and gravity are balanced. As a result, the axis of the power generator 20 matches the direction of the tidal current, becomes horizontal, and faces the tidal current. At this time, since the axis of the power generation device 20 coincides with the direction of the tidal current, the moment generated by the force that the casing 23 receives from the tidal current becomes 0 (zero).

a x (buoyancy of power generator) > b x (gravity of power generator)
, a moment acts on the mooring point 25 to direct the second opening 22 upward (in the counterclockwise direction in FIG. 3). Therefore, the angle θ between the axis of the power generator 20 and the tidal current becomes positive (θ>0 degrees), and the moment the power generator 20 receives from the tidal current and the moment generated in the power generator 20 by the buoyancy and gravity of the power generator 29 are equal to each other. At a balanced angle, the generator set 20 is nearly stationary.

As shown in FIG. 1, the power generation device 20 is flowed facing the flow with the first opening 21 facing upstream and the second opening 22 facing downstream. Since the length of the mooring cable 30 is finite, the power generator 20 sinks into the sea when it is swept downstream.

The turbine 27 rotates when the power generator 20 sinks into the sea with tidal currents. As the turbine 27 rotates, the shaft of the generator 26 rotates and the generator 26 rotates.

The power generator 20 has the same structure as a wind turbine using a so-called wind lens. That is, a stronger flow hits the turbine 27 due to the casing 23 acting as a fluid collector. In addition, since a vortex is formed downstream of the casing 23, the pressure near the second opening 22 is reduced and the seawater flows faster. Therefore, power generation efficiency is improved.

FIG. 8 is a side view showing the posture of the tidal current power generation system of the present embodiment when the tidal current is even greater.

As the tidal current increases, the force that pushes the power generation device 20 in the horizontal direction increases, so the power generation device 20 sinks deeper. The power generation device 20 is stabilized at a position where the force received from the tidal current and the buoyancy received by the mooring cable 30, the intermediate weight 40, and the power generation device 20 are balanced.

When the tidal current further increases, the intermediate weight 40 first contacts the seabed 51 . When the intermediate weight 40 comes into contact with the seabed 51, apparently, the gravity acting from the intermediate weight 40 and the anchor 50 of the mooring cable 30 to the intermediate weight 40 disappears. Therefore, apparently, the buoyancy acting on the power generation device 20 is increased. As a result, sinking of the power generation device 20 is suppressed.

Thus, in the tidal current power generation system 10 of the present embodiment, even when the tidal current becomes large, the possibility of the power generating device 20 contacting the seabed 51 is reduced without using a detector or the like. As a result, the possibility of damage due to contact of the power generation device 20 with the seabed is reduced. Therefore, the tidal power generation system 10 can be made economical and highly reliable. In addition, since the tidal current is stronger above the seabed 51 to some extent than near the seabed 51, the tidal current power generation system 20 of the present embodiment does not reduce the power generation amount so much.

Even when the direction of the tidal current changes, such as when the direction of the tidal current reverses due to a change from a rising tide to a falling tide, the power generator 20 faces the tidal current and generates power. As a result, the power generation efficiency of the power generator 20 can be improved.

In addition, in the tidal current power generation system of the present embodiment, the casing 23 is provided with the horizontal blades 24, so vibrations in the rotation direction about the axis are suppressed. If the portion of the mooring cable 30 attached to the horizontal wing 24 is rotatable, the mooring point 25 of the horizontal wing 24 will rotate according to the change in the attitude of the casing 23, so excessive stress will not be applied to the mooring point.

The buoyancy center 201 of the power generation device 20 is located closer to the second opening 22 than the mooring point 25 is. Therefore, when the tidal current becomes small and power generation is no longer possible, the power generation device 20 rotates about 90 degrees and changes its posture so that the second opening 22 faces upward. Therefore, the attachment portion of the mooring cable 30 does not rotate in the same direction and twist is not accumulated.

Furthermore, by forming the center of buoyancy 201 of the power generation device 20 closer to the second opening 22 than the mooring point 25, the power generation device 20 has a posture in which the second opening 22 faces upward when the tide becomes small. take. Since the second opening 22 is larger than the first opening 21, when the second opening 22 is facing upward, access from the sea is easy and maintenance is easy. In addition, since the second opening 22, which is larger than the first opening 21, faces upward, the moment generated by the force that the power generation device 20 receives from the tidal current is induced in the direction of the power generation device 20 from the first opening 21 to the second opening 22. becomes parallel to the current. Therefore, even when the tidal current is slow, the first opening 21 is on the upstream side and the second opening 22 is on the downstream side.

In the present embodiment, the intermediate weight 40 is fixed to the mooring cable 30, but any weight may be used as long as it pulls the mooring cable 30 vertically downward by gravity. For example, a rope may be fixed to the mooring cable 30 and a weight attached to the lower end of the rope. Moreover, the number of intermediate weights 40 may be plural. Furthermore, the intermediate weight 40 may be attached to the mooring cable 30 so as to be movable within a predetermined range of the central portion of the mooring cable 30 .

In the present embodiment, the casing 23 has an annular cross section surrounded by an outer circle and an inner circle, but it is not limited to a circle and may be polygonal, for example, an outer circle and an inner circle. Either one or both of may be polygons. Also, one or both of the outer circle and the inner circle may be ellipses. Furthermore, from the first opening 21 to the second opening, the shape may change from a circle to an ellipse or from an ellipse to a circle, or from a circle to a polygon or from a polygon to a circle.

[Second embodiment]
FIG. 9 is a side view of a second embodiment of a tidal power generation system according to the present invention.

The tidal current power generation system 10 of the present embodiment is obtained by removing the intermediate cone 40 from the tidal current power generation system of the first embodiment (see FIG. 1, for example).

When the magnitude of the tidal current exceeds a certain threshold, the generator 20 is caused to flow in the direction of arrow 92 . A clockwise moment 922 acts on the mooring point 25 when the angle θ between the axis of the generator 20 and the current is positive (θ>0 degrees). When θ=0 degrees, if the casing 23 is axially symmetrical about the axis extending from the first opening 21 to the second opening 22 as in the present embodiment, the moment 922 becomes 0 due to the symmetry. (zero).

If the distance between the mooring point 25 and the center of buoyancy 201 is a, and the distance between the mooring point 25 and the center of gravity 202 is b,
a x (buoyancy of power generator) = b x (gravitational force of power generator)
When , the moment caused by the buoyancy of the generator 20 and gravity are balanced. As a result, the axis of the power generation device 20 is aligned with the direction of the tidal current and faces horizontally. At this time, since the axis of the power generation device 20 coincides with the direction of the tidal current, the moment generated by the force that the casing 23 receives from the tidal current becomes 0 (zero).

a x (buoyancy of power generator) > b x (gravity of power generator)
, a moment acts on the mooring point 25 to direct the second opening 22 upward (in the counterclockwise direction in FIG. 3). Therefore, the angle θ between the axis of the power generator 20 and the tidal current becomes positive (θ>0 degrees), and the moment the power generator 20 receives from the tidal current and the moment generated in the power generator 20 by the buoyancy and gravity of the power generator 20 are equal to each other. At a balanced angle, the generator set 20 is nearly stationary.

Moreover, when the maximum magnitude of the tidal current is known in advance, the relationship between the buoyancy and gravity of the power generation device 20 can be appropriately defined to prevent contact with the seabed 51 .

In order to adjust the positional relationship between the center of buoyancy and the center of gravity of the generator 20 , an additional mass may be fixed substantially coaxially with the generator 26 . The additional mass may be a nut portion of a screw and nut mechanism, or may be in the form of stacking and fixing a plurality of mass plates of unit weight.

[Third embodiment]
FIG. 10 is a side view of a third embodiment of a tidal power generation system according to the present invention. FIG. 11 is a top view of the tidal power generation system of this embodiment.

The tidal power generation system 11 of this embodiment has four mooring cables 30 . Also, the intermediate weight 40 is fixed to the center of each mooring cable 30 . The four mooring cables 30 are provided two each on each side of the power generator 20 in the direction of the tidal current. The mooring lines 30 positioned on the same side of the power generation device 20 in the direction of the tidal current are anchored to the seabed at positions spaced apart in the direction crossing the tidal current. The width of the anchoring position of the mooring cable 30 located on the same side of the power generation device 20 in the direction of the tidal current is wider than the width of the attachment position of the mooring cable 30 to the power generation device 20 .

Even in such a tidal current power generation system 11, the direction of the tidal current is generally constant, although the direction is opposite at high tide and ebb tide. Therefore, even if the power generator 20 is tethered with the four mooring cables 30, it can face the direction of the tidal current substantially.

FIG. 12 is a side view showing the posture of the tidal current power generation system according to the present embodiment when the current is intermittent.

At the time of rest, that is, when there is no tidal current or the magnitude of the tidal current is less than a certain threshold, the total buoyancy received by the mooring rope 30, the intermediate weight 40, and the power generator 20 is and the power generation device 20, the second opening 22 of the casing 23 faces upward and stands still. If the mooring line 30 is long enough, the casing 23 floats on the sea surface.

As the tidal current increases, the force that pushes the power generation device 20 in the horizontal direction increases, so that the power generation device 20 sinks deeply as shown in FIG. 9 . The power generation device 20 is stabilized at a position where the force received from the tidal current and the buoyancy received by the mooring cable 30, the intermediate weight 40, and the power generation device 20 are balanced. At this time, the intermediate weight 40 attached to the mooring cable 30 on the downstream side sinks deeper than the intermediate weight 40 on the upstream side.

FIG. 13 is a side view showing the attitude of the tidal power generation system of the present embodiment when the tidal current is larger.

When the current becomes stronger, the intermediate weight 40 attached to the mooring line 30 on the downstream side first contacts the seabed 51 . When the intermediate weight 40 comes into contact with the seabed 51, apparently, the gravity acting from the intermediate weight 40 and the anchor 50 of the mooring cable 30 to the intermediate weight 40 disappears. Therefore, apparently, the buoyancy acting on the power generation device 20 is increased. As a result, sinking of the power generation device 20 is suppressed.

FIG. 14 is a side view showing the attitude of the tidal power generation system of the present embodiment when the tidal current is even greater.

14, the intermediate weight 40 attached to the mooring cable 30 on the upstream side also comes into contact with the seabed 51. As shown in FIG. When the intermediate weight 40 comes into contact with the seabed 51, apparently, the gravity acting from the intermediate weight 40 and the anchor 50 of the mooring cable 30 to the intermediate weight 40 disappears. Therefore, apparently, the buoyancy acting on the power generation device 20 is increased. As a result, sinking of the power generation device 20 is further suppressed.

Thus, in the tidal current power generation system 11 of the present embodiment, the possibility of the power generating device 20 contacting the seabed 51 is reduced even when the tidal current becomes large. As a result, the possibility of damage due to contact of the power generation device 20 with the seabed is reduced. In addition, since the tidal current is somewhat stronger above the seabed 51 than near the seabed 51, the tidal current power generation system 11 of the present embodiment does not reduce the power generation amount so much.

Furthermore, in this embodiment, since the intermediate weight 40 is arranged on the upstream side and the downstream side, the change in buoyancy due to the intermediate weight 40 landing on the seabed 51 can be made in two stages. Therefore, it is possible to maintain an appropriate height in seawater for a wider range of tidal currents.

Moreover, in this embodiment, the mooring ropes 30 are anchored to the seabed at locations spaced apart in the direction crossing the tidal current. Therefore, even if the direction of the tidal current changes, the intermediate weight 40 attached to one mooring cable 30 across the direction of the tidal current comes into contact with the seabed 51 first. Horizontal shaking (yawing) is suppressed.

DESCRIPTION OF SYMBOLS 10... Tidal power generation system 11... Tidal power generation system 20... Power generation apparatus 21... 1st opening 22... 2nd opening 23... Casing 24... Horizontal wing 25... Mooring point 26... Generator 27... Turbine 30 Mooring cable 40 Intermediate weight 50 Anchor 51 Seabed 201 Center of buoyancy 202 Center of gravity 922 Moment

Claims (3)

A power generation device comprising: a turbine rotated by a tidal current; a generator generating power by the rotation of the turbine; and a casing holding the turbine and the generator inside and having mooring points formed on the outside;
a mooring line anchored to the seabed, extending from the seabed to the casing and anchored to the mooring point;
A tidal power generation system comprising:
The casing has an annular shape penetrating toward a first opening and a second opening, and the second opening is formed in a funnel shape larger than the first opening,
the anchoring point is closer to the first opening than the second opening;
the center of buoyancy of the power generation device is closer to the second opening than the mooring point;
the center of gravity of the power generation device is closer to the second opening than the center of buoyancy;
A value obtained by multiplying the distance between the center of buoyancy and the mooring point by the buoyancy of the power generation device is greater than or equal to the value obtained by multiplying the distance between the center of gravity and the mooring point by the gravity of the power generation device.
A tidal current power generation system characterized by: The tidal current power generation system according to claim 1, further comprising an intermediate weight that pulls the mooring line vertically downward between the casing and the seabed. 3. A tidal current power generation system according to claim 1 or claim 2, wherein said mooring lines include two mooring lines anchored to said seabed at locations spaced apart in the direction of said tidal current flow.

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