U.S. patent application number 13/058950 was filed with the patent office on 2011-06-23 for method for controlling heliostat used for condensing of sunlight and device thereof.
Invention is credited to Kazuaki Ezawa, Takashi Kawaguchi.
Application Number | 20110146663 13/058950 |
Document ID | / |
Family ID | 42128481 |
Filed Date | 2011-06-23 |
United States Patent
Application |
20110146663 |
Kind Code |
A1 |
Ezawa; Kazuaki ; et
al. |
June 23, 2011 |
METHOD FOR CONTROLLING HELIOSTAT USED FOR CONDENSING OF SUNLIGHT
AND DEVICE THEREOF
Abstract
Provided are a method for controlling a heliostat used for
collecting of sunlight and a device of the method that achieve: a
high sunlight collecting efficiency with a high light collecting
rate by allowing no deviation of a light collecting point (a focal
point) of sunlight; and a high area arrangement efficiency by
having such a configuration in which no rotation by means of a
rotation mechanism is carried out. The method is a method for
controlling a heliostat being used for collecting of sunlight and
having multiple reflecting mirrors in a way that the heliostat
tracks the sun in motion, reflects sunlight, and collects the
sunlight at a predetermined focal point. The method includes: a
step of adjusting the multiple reflecting mirrors so that the
multiple reflecting mirrors have a focal point at a predetermined
distance; and a step of controlling the multiple reflecting mirrors
to track the sun while light beams reflected from the reflecting
mirrors have a focal point at an arbitrary point, the multiple
reflecting mirrors being configured to tilt in conjunction with
each other. In the method, while maintaining a state where the
coordinates of predetermined points of the respective reflecting
mirrors are fixed, the reflecting mirrors are operated in
conjunction with each other.
Inventors: |
Ezawa; Kazuaki; (Tokyo,
JP) ; Kawaguchi; Takashi; (Tokyo, JP) |
Family ID: |
42128481 |
Appl. No.: |
13/058950 |
Filed: |
August 28, 2009 |
PCT Filed: |
August 28, 2009 |
PCT NO: |
PCT/JP2009/004238 |
371 Date: |
February 14, 2011 |
Current U.S.
Class: |
126/600 ;
126/714 |
Current CPC
Class: |
F24S 30/455 20180501;
Y02E 10/46 20130101; G02B 19/0019 20130101; G02B 19/0042 20130101;
F24S 2030/17 20180501; G02B 19/008 20130101; F24S 23/77 20180501;
F24S 2030/131 20180501; G02B 7/1827 20130101; F24S 50/20 20180501;
F03G 6/06 20130101; Y02E 10/47 20130101; F24S 30/452 20180501; G02B
7/183 20130101; F24S 2030/136 20180501 |
Class at
Publication: |
126/600 ;
126/714 |
International
Class: |
F24J 2/38 20060101
F24J002/38; F24J 2/00 20060101 F24J002/00; F24J 2/34 20060101
F24J002/34 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 27, 2008 |
JP |
2008-275263 |
Claims
1. A method for controlling a heliostat, which is used for
collecting of sunlight and has a plurality of reflecting mirrors,
in a way that the heliostat tracks the sun in motion, reflects
sunlight, and collects the sunlight at a predetermined focal point,
the method characterized by comprising the steps of: adjusting the
plurality of reflecting mirrors so that the plurality of reflecting
mirrors have a focal point at a predetermined distance; and
controlling the plurality of reflecting mirrors so that the
plurality of reflecting mirrors track the sun and light beams
reflected from the respective reflecting mirrors have a focal point
at an arbitrary point, the plurality of reflecting mirrors being
configured to tilt in conjunction with each other, the method
characterized in that the reflecting mirrors are operated in
conjunction with each other while maintaining a state where
coordinates of predetermined points of the respective reflecting
mirrors are fixed.
2. The method for controlling a heliostat according to claim 1,
characterized in that the reflecting mirrors are operated in
conjunction with each other while maintaining a state where
coordinates of centers of the respective reflecting mirrors are
fixed.
3. The method for controlling a heliostat according to claim 1,
characterized in that a focal point formed by the plurality of
reflecting mirrors moves on a celestial sphere surface having an
arbitrary radius in such a way to prevent comatic aberration.
4. The method for controlling a heliostat according to claim 1,
characterized in that directions of the plurality of reflecting
mirrors are controlled in conjunction with each other by two
different link mechanisms.
5. A heliostat used for collecting of sunlight and configured to
arrange a plurality of reflecting mirrors therein in such a way
that the plurality of reflecting mirrors have a focal point, the
heliostat characterized in that: the plurality of reflecting
mirrors are mounted on pedestals with tilting mechanisms in
between, respectively; the plurality of tilting mechanisms are
connected to each other by a first axis link and a second axis link
which are directed in two different directions; and the plurality
of tilting mechanisms change an orientation in conjunction with
each other by the links.
6. The heliostat according to claim 5, characterized in that: the
first axis link and the second axis link are rod-shaped links, are
provided in directions orthogonal to each other, and are connected
to respective driving devices; and the driving devices are
controlled so as to configure that a position of a focal point of
the plurality of reflecting mirrors is movable through the
respective links and the respective tilting mechanisms.
7. A solar thermal power generation plant, characterized by
comprising a plurality of heliostats according to claim 5,
characterized in that sunlight is collected at a heat receiving
part using a molten salt as a heat medium so as to carry out solar
thermal power generation.
Description
TECHNICAL FIELD
[0001] The present invention relates to a method for controlling a
heliostat used for collecting of sunlight for the purpose of
tracking the sun and collecting reflected light at an arbitrary
point (a focal point), and relates to a device of the method.
BACKGROUND ART
[0002] In recent years, the depletion and the soaring prices of
petroleum resources have been matters of concern. In the meantime,
a shift from petroleum resources, which come to be one of the
causes of global warming, to alternative energy resources has been
studied. As one of such alternative energy sources, solar thermal
power generation is available in which sunlight is collected and
used as energy.
[0003] In the solar thermal power generation, a heliostat used for
collecting of sunlight includes multiple reflecting mirrors
(facets). The heliostat is either configured so that sunlight can
be reflected and collected at a heat receiving part or the like and
then the heat thereof is used for electric power generation, or
configured as a center-reflector-type solar thermal power
generation plant in which light beams reflected from facets are
re-reflected from a large reflecting mirror (a center reflector)
and collected at a heat receiving part. Here, for the purpose of
increasing a power generation efficiency, proposed is the invention
in which a heliostat is configured to track movements of sunlight
(refer to Patent Document 1, for example).
[0004] FIG. 14 illustrates a lateral view of an example of a
heliostat used for solar thermal power generation. A conventional
heliostat 5 includes multiple facets 20. Multiple sets (3 sets in
FIG. 14) each including the facet 20 disposed on a pedestal 47 are
provided on a rotation mechanism 45. The thus provided facets 20
respectively have seats connected to each other by a link mechanism
46. Accordingly, it is configured that the link mechanism 46 causes
the conventional heliostat 5 to perform rise-and-fall motions 44,
and that the rotation mechanism 45 causes the conventional
heliostat 5 to perform rotation motions 43. It is configured that
these motions enable the conventional heliostat 5 to track the sun
and to reflect and collect the sunlight at an arbitrary place (for
example, a heat receiving part, a reflecting mirror, or the like in
the solar thermal power generation).
[0005] FIG. 15 is a schematic plan view illustrating the appearance
of the facets 20 mounted on the conventional heliostat 5. In
general, multiple facets 20 are installed in combination of a
certain number thereof (14 facets in FIG. 15). The facets 20
described here each have one side of approximately 450 mm.
PRIOR ART DOCUMENT
Patent Document
[0006] Patent Document 1: Japanese patent application Kokai
publication No. 2004-37037
SUMMARY OF THE INVENTION
Problem to be Solved by the Invention
[0007] However, a heliostat described in Patent Document 1 is
configured so as to track sunlight by rotation on the X-axis and
the Y-axis as shown in FIG. 3 of Patent Document 1. The facets move
around an intersection point of the X-axis and the Y-axis of the
heliostat. Accordingly, a phenomenon (comatic aberration) occurs in
which the position of a focal point formed by reflected light beams
from the respective facets deviates, leading to a problem of low
light collecting rate. The same applies to the above-described
conventional heliostat 5 shown in FIG. 14. The conventional
heliostat 5 also has a problem in which a focal point distance of
the facet 20 located away from the center deviates due to the
rotation 43 of the conventional heliostat 5 around the center of
the rotation mechanism 45 as a base point.
[0008] This phenomenon of focal point deviation (comatic
aberration) will be described with reference to FIG. 8 and FIG. 9.
FIG. 8 is a pattern diagram of the multiple facets 20 (3 facets in
FIG. 8) being installed in the heliostat 5, and shows how the
heliostat operates around a rise-and-fall and rotation center O as
a base point.
[0009] The facets 20 are installed with their angles adjusted in
advance so that the facets 20 can reflect sunlight S irradiated
from the sun 40 and thus reflected light beams R can form a focal
point F at, for example, a heat receiving part, a reflecting
mirror, or the like. FIG. 9 shows a situation when the sun 40 has
moved. The movement of the sun 40 changes the angle of the sunlight
S irradiated on the respective facets 20. Accordingly, the
heliostat 5 again performs rotation motions as well as
rise-and-fall motions in order to correct the position of the focal
point for light collecting.
[0010] At this time, rotation motions or rise-and-fall motions of
the heliostat 2 are performed around the above-described
rise-and-fall and rotation center O as a base point. Accordingly,
the facet 20 located on the left in FIG. 9 ends up shifting upward
in the drawing by a facet shift distance d, while the facet 20
located on the right as well ends up shifting downward in the
drawing by the facet shift distance d. Therefore, the reflected
light beams R do not form a focal point at a position which should
be the focal point F on a heat receiving part or the like as shown
in FIG. 9, resulting in the situation where the reflected light
beams R diffuse by a shift distance e from the focal point. This
phenomenon is called comatic aberration. Even if the heliostat 5 is
adjusted in its installation so that the reflected light beams R
intersect with each other at the focal point F, the reflected light
beams R would not intersect with each other at the focal point F
because of the rotation and rise-and-fall motions.
[0011] The comatic aberration described above results in a decrease
in light collecting efficiency. Thus, there arises a problem
especially for a solar thermal power generation plant, which uses a
large-scale number of the heliostats as many as hundreds or
thousands, that a decrease in light collecting efficiency causes a
significant decrease in power generation efficiency of the
plant.
[0012] Thus, the present invention has been made in order to solve
the above-described problems. An object of the present invention is
to provide a method for controlling a heliostat used for collecting
of sunlight and a device of the method, the method and the device
achieving: a high sunlight collecting efficiency by allowing no
deviation of a light collecting point (a focal point) of sunlight;
and a high area arrangement efficiency by having a configuration in
which no rotation by means of a rotation mechanism is carried
out.
[0013] Additionally, an object of the present invention is to
reduce costs for installation work of a device in a solar thermal
power generation plant by having a device configuration which
allows the installation and adjustment work of facets to be carried
out easily, and is further to provide a highly-efficient solar
thermal power generation plant.
Means for Solving the Problem
[0014] A method for controlling a heliostat according to the
present invention to achieve the above object is a method for
controlling a heliostat, which is used for collecting of sunlight
and has multiple reflecting mirrors, in a way that the heliostat
tracks the sun in motion, reflects sunlight, and collects the
sunlight at a predetermined focal point. The method is
characterized as follows. Specifically, the method includes the
steps of: adjusting the multiple reflecting mirrors so that the
multiple reflecting mirrors have a focal point at a predetermined
distance; and controlling the multiple reflecting mirrors so that
the multiple reflecting mirrors track the sun and light beams
reflected from the respective reflecting mirrors have a focal point
at an arbitrary point, the multiple reflecting mirrors being
configured to tilt in conjunction with each other. The reflecting
mirrors are operated in conjunction with each other while
maintaining a state where coordinates of predetermined points of
the respective reflecting mirrors are fixed.
[0015] In this configuration, control is designed such that the
multiple facets each have a center for rise-and-fall motions and
rotation motions (tilt motions); therefore, it is possible to
prevent occurrence of the comatic aberration. Specifically, by
having a configuration in which each of the facets 20 has a
rise-and-fall and rotation center as shown in FIG. 10, the control
method allows the facet shift distance d to be zero, thereby
preventing occurrence of the comatic aberration.
[0016] Further, control is designed such that the multiple facets
track the sun in conjunction with each other. Accordingly, after
the multiple facets are adjusted in the early stage so as to have a
focal point at an arbitrary position, the focal point can be easily
maintained.
[0017] Here, in solar thermal power generation, control is carried
out in such a way that the position of a focal point formed by
reflected light beams is kept constant regardless of movements of
the sun (a light source). The principle in this control is the same
as that of the above-described control to move the focal point.
[0018] The above-described method for controlling a heliostat is
characterized in that the reflecting mirrors are operated in
conjunction with each other while maintaining a state where
coordinates of centers of the respective reflecting mirrors are
fixed.
[0019] In this configuration, the center of each facet is set as a
center for rise-and-fall motions and rotation motions (tilt
motions); therefore, even the comatic aberration occurring at an
end portion of the facet can be prevented. In the present
invention, the facet supposedly has a size of 450 square mm to 1000
square mm. If, for example, the rise-and-fall and rotation center
of a facet is set at a corner of the facet, the distance from the
rise-and-fall and rotation center to the other edge corner would be
large, resulting in a shift distance d of the facet.
[0020] In this respect, the center of the facet is set as the
rise-and-fall and rotation center in this control method.
Accordingly, the facet shift distance d can be brought as close as
possible to zero; therefore, occurrence of the comatic aberration
can be inhibited within a significantly small range.
[0021] The above-described method for controlling a heliostat is
characterized in that a focal point formed by the multiple
reflecting mirrors is movable on a celestial sphere surface having
an arbitrary radius without occurrence of comatic aberration.
[0022] The above-described method for controlling a heliostat is
characterized in that directions of the multiple reflecting mirrors
are controlled in conjunction with each other by two different link
mechanisms.
[0023] In this configuration, control on the facets for guiding the
reflected light beams to an arbitrary direction is carried out by a
link mechanism, which has at least two different vector directions,
simultaneously on the multiple facets. Therefore, positional
control on the facets can be easily and reliably achieved with a
simple mechanism.
[0024] A heliostat to achieve the above object is a heliostat used
for collecting of sunlight and configured to arrange multiple
reflecting mirrors therein in such a way that the multiple
reflecting mirrors have a focal point. The heliostat is
characterized as follows. Specifically, the multiple reflecting
mirrors are mounted on pedestals with tilting mechanisms in
between, respectively. The multiple tilting mechanisms are
connected to each other by a first axis link (X-axis link) and a
second axis link (Y-axis link) which are directed in two different
directions. The multiple tilting mechanisms change an orientation
in conjunction with each other by the links.
[0025] In this configuration, the multiple tilting mechanisms are
connected to each other with two shafts, which are the first axis
link and the second axis link, directed in different directions.
Accordingly, the heliostat can be easily controlled while
maintaining the focal point of the reflected light beams by tilting
the multiple facets simultaneously.
[0026] The above-described heliostat is characterized as follows.
Specifically, the first axis link (X-axis link) and the second axis
link (Y-axis link) are rod-shaped links, are provided in directions
orthogonal to each other, and are connected to respective driving
devices. The driving devices are controlled so as to configure that
a position of a focal point of the multiple reflecting mirrors is
movable through the respective links and the respective tilting
mechanisms.
[0027] In this configuration, the multiple tilting mechanisms are
connected to each other with the first axis link (X-axis link) and
the second axis link (Y-axis link) which are orthogonal to each
other. Accordingly, the relationship between the amount of
operation of the above driving device and the shift distance of the
focal point can be easily calculated. Therefore, the control on the
facets itself can be easily carried out. Further, the use of the
rod-shaped links can secure a large motion space of the facets.
This allows tracking of movements of the sun in a wide range,
especially in a large-scale solar thermal power generation plant,
leading to an improved power generation efficiency.
[0028] A solar thermal power generation plant to achieve the above
object is characterized as follows. Specifically, the plant
includes multiple heliostats described above, and sunlight is
collected at a heat receiving part using a molten salt as a heat
medium so as to carry out solar thermal power generation.
[0029] In this configuration, the area efficiency of the heliostats
provided in the solar thermal power generation plant is improved
while the reflected light beams can be collected at a heat
receiving part, a reflecting mirror, or the like. Accordingly, a
solar thermal power generation plant having a significantly high
power generation efficiency can be provided. Further, the multiple
facets are tilted by means of a two-shaft link mechanism.
Accordingly, transportation of materials to a site where a solar
thermal power generation plant is to be installed as well as the
installation can be easily carried out. Therefore, installation
costs of the power generation plant can be reduced.
Effects of the Invention
[0030] The method for controlling a heliostat and the device of the
method according to the present invention can provide a method for
controlling a heliostat used for collecting of sunlight and a
device of the method, which achieve: a high sunlight collecting
efficiency by allowing no deviation of a light collecting point (a
focal point) of sunlight; and a high area arrangement efficiency by
having a configuration in which no rotation by means of a rotation
mechanism is carried out.
[0031] Additionally, it is also possible to reduce costs for
installation work of the device in a solar thermal power generation
plant by having a device configuration which allows the
installation and adjustment work of facets to be carried out
easily, and further possible to provide a highly-efficient solar
thermal power generation plant.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] FIG. 1 is a partial enlarged view of a first example of the
present invention.
[0033] FIG. 2 is a schematic view of the first example of the
present invention.
[0034] FIG. 3 is a lateral view of a second example of the present
invention.
[0035] FIG. 4 is a lateral view of the second example of the
present invention.
[0036] FIG. 5 is a lateral view of a third example of the present
invention.
[0037] FIG. 6 is a schematic view illustrating how the third
example of the present invention operates.
[0038] FIG. 7 is a lateral view of a fourth example of the present
invention.
[0039] FIG. 8 is a schematic view illustrating the relationship
between sunlight and its reflected light beams in a conventional
heliostat.
[0040] FIG. 9 is a schematic view illustrating occurrence of
comatic aberration in the conventional heliostat.
[0041] FIG. 10 is a schematic view illustrating the relationship
between sunlight and its reflected light beams in a heliostat of
the present invention.
[0042] FIG. 11 is a schematic view illustrating a movement locus of
a focal point in the heliostat of the present invention.
[0043] FIG. 12 is a schematic view of a solar thermal power
generation plant using the heliostat of the present invention.
[0044] FIG. 13 is a schematic view of a solar thermal power
generation plant using the conventional heliostat.
[0045] FIG. 14 is a schematic view illustrating the conventional
heliostat.
[0046] FIG. 15 is a schematic plan view illustrating facets
arranged in the conventional heliostat.
MODES FOR CARRYING OUT THE INVENTION
[0047] Hereinafter, the present invention will be described
specifically by referring to embodiments illustrated in the
drawings.
Example 1
[0048] FIG. 1 shows a partial enlarged view of a heliostat 1A which
is a first example of the present invention. FIG. 2 shows a
perspective view of the heliostat 1A including nine facets 20. The
facets 20 are fixed by facet bolts 19 to tilting mechanisms 10A,
respectively. The tilting mechanisms 10A are disposed on pedestals
16A, respectively. Further, the tilting mechanisms 16A are
configured to move in conjunction with each other by being
connected to each other in an X-axis direction by an X-axis link
11A with X-axis arm parts 13 in between, and being connected to
each other in a Y-axis direction by a Y-axis link 12A with
universal joints 15 and cylinder mechanisms 14A in between. Here,
installation angles of the facets 20 are adjusted by the facet
bolts 19 in advance so that a focal point can be formed at an
arbitrary point.
[0049] FIG. 2 shows an example of a case where multiple facets 20
are combined to form the heliostat 1A. Here, nine facets 20 are
connected to each other in the X-axis direction and the Y-axis
direction by the links. Edge portions of the links are connected to
an X-axis driving device 17 and a Y-axis driving device 18,
respectively.
[0050] It is configured that a link mechanism is moved by operating
the driving devices 17 and 18 so that inclinations of the facets 20
can be controlled with two shafts. The facets 20 are adjusted in
advance so that a focal point can be formed at an arbitrary point.
When all the facets 20 are moved simultaneously by means of the
link mechanism from this state, only the position of the focal
point can be moved while reflected light beams are being focused on
the point. Accordingly, in a solar thermal power generation plant,
for example, reflected light beams are always focused on a heat
receiving part, a reflecting mirror, or the like even when the sun
moves. Therefore, it is possible to provide a plant having a
significantly high power generation efficiency with no occurrence
of comatic aberration or with minimal comatic aberration.
[0051] In addition, by having a configuration of the link mechanism
as shown in FIG. 2, a large motion space for the facets 20 can be
secured. Accordingly, in a solar thermal power generation plant, it
is possible to increase the range of being able to track the sun,
thereby improving the power generating efficiency. Further, by
changing the shape of the tilting mechanism 10A, it is possible to
achieve a configuration in which the facets 20 can be tilted almost
at 90 degrees in all directions. Especially in a huge solar thermal
power generation plant having a size of hundreds square meters or
larger, it is necessary to tilt the facets 20 largely. When the
motion space of the facets 20 is increased, it is possible to lower
the position where a heat receiving part, a reflecting mirror, or
the like is disposed. Thus, it is possible to achieve cost
reduction in constructing the solar thermal power generation
plant.
Example 2
[0052] FIG. 3 shows a schematic front view of a heliostat 1B which
is a second example of the present invention. FIG. 4 shows a
schematic lateral view thereof. The heliostat 1B is configured in
such a way that facets 20 each having on a lower side thereof a
tilting mechanism 10B rotate in horizontal directions shown in FIG.
3 around a Y-axis link 12B. The multiple tilting mechanism 10B are
connected to each other by an X-axis link 11B as a link mechanism,
and are configured to connect the multiple facets 20 aligned in a
horizontal direction (the X-axis direction) in FIG. 3 so as to
cause the multiple facets 20 to rise and fall in conjunction with
each other.
[0053] Further, rise-and-fall motions in the Y-axis directions
(front-and-back directions with respect to the sheet of FIG. 3, or
horizontal directions in FIG. 4), which are perpendicular to the
X-axis directions in FIG. 3, can be achieved by the links
connecting to the Y-axis links 12B through the multiple facets 20
as shown in FIG. 4.
[0054] The present example allows formation of a compact link
mechanism, thereby being capable of reducing the size of the
structure of the heliostat 1B itself. Thus, costs of manufacturing
and transporting the heliostat 1B can be reduced.
Example 3
[0055] FIG. 5 shows an outline of a heliostat 3A which is a third
example of the present invention. FIG. 6 shows how the heliostat 3A
tracks sunlight. The heliostat 3A includes multiple facets 20 each
having in a lower portion thereof a columnar supporting member 36.
The multiple facets 20 are aligned so as to have a focal point. The
supporting member 36 is formed of a flexible cylinder mechanism 34,
and has a neck portion composed of a spherical joint. The neck
portion is rotatably supported by an intermediate fixing plate 32
with a rotation mechanism 31 in between. The rotation mechanism 31
at the neck portion may be obtained by a joint having a degree of
freedom equal to 2 other than the aforementioned spherical
joint.
[0056] Upper portions of the supporting member 36 are connected to
the facets 20, respectively, with an installation angle adjustment
mechanism 30 in between. When the heliostat is installed, the
installation angles of the respective facets 20 are adjusted by the
installation angle adjustment mechanism 30 so that reflected light
beams from the respective multiple facets 20 can have a focal point
at an arbitrary distance. Lower portions of the respective
supporting members 36 are connected to each other by a link
mechanism 35. When the link mechanism 35 moves on a plane surface,
inclinations of the respective multiple facets 20 can be adjusted
in conjunction with each other. Further, the link mechanism 35
moves on so-called an X-Y axis surface on a plane surface. For this
reason, the connection between the supporting members 36 and the
link mechanism 35 uses a joint which is operable in two X- and
Y-axes, and desirably uses a spherical joint.
[0057] As shown in FIG. 6, when the link mechanism 35 moves on an
upper surface of a bottom plate 33, the facets 20 can each change
the mirror-surface direction, as apparent from the directions of
the respective facet normals. The link mechanism 35 can be moved by
having the cylinder mechanisms 34 to extend. Further, in the case
of installation in a solar thermal power generation plant or the
like, the link mechanism 35 is controlled when the facets 20 track
the sun, so that the sunlight can be always collected at the focal
point on a heat receiving part, a reflecting mirror, or the like.
Having the above-described configuration, the heliostat 3A appears
as a heliostat having two layers including the bottom plate 33 and
the intermediate fixing plate 32, and having a grove of the
supporting members 36 extending below the facets 20. In addition,
the facets 20 stick out from the intermediate fixing plate 32 as
seen like head parts.
Example 4
[0058] FIG. 7 shows a schematic view of a heliostat 3B which is a
fourth example of the present invention. This heliostat 3B is an
example when non-flexible supporting members 36 are used instead of
the flexible cylinder mechanism in the third example. The
supporting members 36 have at neck portions thereof rotation
mechanisms 31 supported by an intermediate fixing plate 32.
Accordingly, when the supporting members 36 having no flexibility
are used, the link mechanism 35 moves in the three-dimensional
space as if floating from the bottom plate 33.
[0059] By having a configuration using no cylinder mechanism 34,
the structure of the heliostat 3B can be simplified. Accordingly,
when, for example, a solar thermal power generation plant is
constructed in a desert, risks of a breakdown and the like due to
sand and heat can be reduced. It is extremely important to use
heliostats requiring less maintenance in a solar thermal power
generation plant which uses hundreds or thousands of the heliostat
3B. In other words, since costs for power generation are largely
affected by the amount of maintenance required, the costs for power
generation can be reduced by the present example.
Effects of Carrying Out the Present Invention
[0060] FIG. 10 is a schematic view illustrating the appearances of
sunlight S and reflected light beams R in the heliostats 1A and 1B
to which the controlling method and the device using the
controlling method of the present invention are applied. Each of
the facets 20 has an own rise-and-fall and rotation center O of the
facet 20. Accordingly, even when the facets 20 moves as tracking
the sun 40, a deviation (a shift distance e from the focal point)
of the reflected light beams R from a focal point F as shown in
FIG. 9 does not occur. Especially in solar thermal power generation
plants, the distances from the focal point to the facets 20 are
hundreds of meters to thousands of meters in some cases, depending
on the scale of the plant. In such cases, even if the shift
distance d of the facets is small, the shift distance e from the
focal point will be huge. For this reason, with the method for
controlling a heliostat and the device of the method according to
the present invention, which allow occurrence of no comatic
aberration (e.apprxeq.0), it is now possible to provide a highly
efficient solar thermal power generation plant.
[0061] FIG. 11 schematically shows a movement locus of the focal
point F in the state where no comatic aberration occurs. When the
position of the focal point F is moved by tilting the facets 20,
the focal point F moves on a celestial sphere 41 with a focal point
distance constant. This shows the state of zero comatic
aberration.
[0062] It should be noted that, a solar thermal power generation
plant is configured that the reflected light beams R are always
collected at a heat receiving part, a reflecting mirror (a center
reflector), or the like, that is, the focal point F is being fixed,
while the sun as a light source is being tracked. This also is
similarly affected by the comatic aberration. Accordingly,
utilization of the present invention enables that the reflected
light beams R are collected at a fixed position regardless of
movements of the sun without being affected by the comatic
aberration. Thus, a method for controlling a heliostat and a device
of the method which achieve a high sunlight collecting efficiency
can be provided.
(Laying in Solar Thermal Power Generation Plant)
[0063] FIG. 13 shows a schematic view of a solar thermal power
generation plant 6 in which conventional heliostats 5 are provided.
Being rotated by means of a rotation mechanism 45 as shown in FIG.
14, the conventional heliostats 5 need to be disposed so that
heliostat rotation ranges 42 shown in FIG. 13 may not overlap each
other.
[0064] On the other hand, having no conventional rotation
mechanism, the heliostats 1A and 1B of the present invention can be
arranged at smaller intervals from adjacent ones, thereby achieving
a high area arrangement efficiency. Specifically, the number of
heliostats which can be mounted for a heat receiving part or a
center reflector arranged at the focal point F can be largely
increased; thus, it has become possible to achieve significant
improvement in the power generation efficiency in the solar thermal
power generation plant 2.
[0065] As described above, according to the present invention, a
method for controlling a heliostat used for collecting of sunlight
and a device of the method can be provided, the method and the
device achieving: a high sunlight collecting efficiency by allowing
no deviation of a light collecting point (a focal point) of
sunlight; and a high area arrangement efficiency by having a
configuration in which no rotation by means of a rotation mechanism
is carried out.
[0066] Further, a reduction in costs for installation work of the
device in a solar thermal power generation plant is achieved by
having a device configuration which allows the installation and
adjustment work of facets to be carried out easily. In addition, a
highly-efficient solar thermal power generation plant can be
provided.
EXPLANATION OF REFERENCE NUMERALS
[0067] 1A, 1B X-Y driven heliostat [0068] 2 solar thermal power
generation plant [0069] 3A, 3B X-Y driven heliostat [0070] 10
tilting mechanism [0071] 11 X-axis link [0072] 12 Y-axis link
[0073] 13 X-axis arm part [0074] 14 cylinder mechanism [0075] 15
universal joint [0076] 16 pedestal [0077] 17 X-axis driving device
[0078] 18 Y-axis driving device [0079] 19 facet bolt [0080] 20
facet (reflecting mirror)
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