JP2012220270A - Sunlight detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sunlight detector in which even a light detection sensor that is not formed in a long shape can reliably secure a sunlight capture angle.SOLUTION: The sunlight detector uses light detection sensors 20a, 20b, 21a and 21b that are not formed in long shapes and therefore it is advantageous in terms of cost. An interval D equal to or larger than a diameter of spot P is ensured between the light detection sensors 20a, 20b, 21a and 21b and the inner surface of a box 6, thereby preventing irregular reflected light that is reflected on the inner surface from exerting a bad influence.

Description

  The present invention relates to a solar light detection apparatus.

  To rotate the heliostat reflector, which keeps the solar panel driven to rotate while following the sun while keeping the solar panel facing the sun, or tracking the sun. A solar detection device is used.

  In this type of solar light detection device, for example, a circular introduction hole for introducing sunlight is formed on one surface of a box having a cylindrical inner surface, and a pair of opposed internal cross-sectionally orthogonal two surfaces is formed on the opposite inner bottom surface. A total of four photodetection sensors are provided. As this light detection sensor, a general solar cell or photodiode is used (for example, see Patent Document 1).

  For example, in the case of two-axis control of the horizontal direction and the altitude direction that controls the direction by the sunlight detection device, the light detection sensor is arranged with the directionality related to these directions. In order to receive sunlight, the light detection sensor employs a large area sensor that divides one light receiving area into four small areas with no gaps and covers each area.

  And when the spot of sunlight introduced from the introduction hole illuminates the center of each pair of light detection sensors, the amount of light received by each pair of light detection sensors is equal, and the output from the light detection sensors is also equal, No signal is output from the control unit to the external drive system, but if the spot of sunlight deviates from the center of the light detection sensor, the amount of light received by the pair of light detection sensors is different, so the output from the light detection sensor is also different. The controller detects the state and outputs a signal to the outside so that the received light amounts are equal. Therefore, the photodetection sensor is always maintained so that the amount of received light is equal, and in the case of what is controlled, for example, a driving type solar cell panel, the solar cell panel is always maintained in a state of facing the sun.

JP-A-9-243354

  However, such a conventional technique is disadvantageous in cost because it uses a large area photodetection sensor. That is, a large-area light detection sensor is expensive, and in the case of a system including a large number of solar light detection devices, the overall cost is also affected.

  Therefore, as a result of earnest research, the inventor noticed that a large area of a light detection sensor includes a useless part as a sensor because most of the light detection sensor is located in the spot. It was found that the spot position can be detected even if a part of the spot is located within the sunlight spot.

  The present invention has been made by paying attention to such a conventional technique, and an object of the present invention is to provide a solar light detection device that can reliably secure a sunlight capturing angle even with a small area light detection sensor. It is said.

  The invention according to claim 1 is a state in which a sunlight introduction hole is formed at the center of one surface of the box and the bottom surface center is sandwiched in two directions orthogonal to the inner bottom surface on the side opposite to the one surface of the box. And a control unit that outputs a signal to the outside so that the amount of light received by the pair of light detection sensors in each direction is equalized by the spot of sunlight introduced from the introduction hole. A sunlight detection device provided, wherein the light detection sensor is provided at a position where an outer edge of the sunlight spot introduced from the introduction hole passes, and a spot of sunlight is provided between the light detection sensor and the inner surface of the box. An interval equal to or larger than the diameter is provided.

  According to a second aspect of the present invention, the length dimension in each direction of the light detection sensor is a non-elongate shape within twice the width dimension, and the interval between the opposed light detection sensors is related to the size of the sunlight spot. It is characterized by being arranged.

  The invention described in claim 3 is characterized in that the box has a cylindrical inner surface and the introduction hole is circular.

  The invention according to claim 4 is characterized in that the two orthogonal directions in which the light detection sensor is arranged are a direction related to the declination direction of the equatorial ritual heliostat and a direction related to the ecliptic direction.

  The invention described in claim 5 is characterized in that the sunlight introduced from the introduction hole is sunlight reflected by the reflecting surface of the heliostat.

  According to the first aspect of the present invention, since the light detection sensor is provided at a position through which the sunlight inner edge introduced from the introduction hole passes, even a small area or a part of the inner edge is included. For example, it can be controlled as a sensor. In addition, since an interval equal to or larger than the spot diameter is secured between the light detection sensor and the inner surface of the box, the light detection sensor is controlled so that the spot on the terminal of the light detection sensor does not hit the inner surface of the box. Occasionally, irregularly reflected light reflected from the inner surface does not have an adverse effect.

  According to the second aspect of the present invention, since the photodetection sensor has a non-elongated shape with a length dimension within twice the width dimension, it is less expensive than the elongate shape.

  According to the invention described in claim 3, since the box has a cylindrical inner surface and the introduction hole is circular, the spot of sunlight is substantially circular, and the arrangement of the light detection sensor is easy.

  According to the fourth aspect of the present invention, since the two orthogonal directions in which the light detection sensor is arranged are directions related to the declination direction and the ecliptic direction of the equatorial ritual heliostat, the heliostat is controlled with high accuracy. be able to.

  According to the fifth aspect of the present invention, sunlight actually reflected by the heliostat can be detected, so that the heliostat can be controlled with higher accuracy.

The perspective view which shows the equatorial ritual type heliostat which concerns on embodiment of this invention. The schematic explanatory drawing which shows the rotation direction of the mirror of a heliostat. The perspective view which shows a box. Sectional drawing of the box in alignment with the arrow SA-SA line in FIG. Sectional drawing of the box which follows the arrow SB-SB line | wire in FIG. The figure which shows the control part of a photon detection sensor. The top view which shows the reflective state before control of the sunlight by a sensor mirror. The top view which shows the reflective state in control of the sunlight by a sensor mirror. Explanatory drawing which shows the output of a photon detection sensor. The schematic diagram showing the relationship between the position of the spot P and the output of a photon detection sensor.

  1 to 10 are views showing a preferred embodiment of the present invention. In this embodiment, a solar detection device for a heliostat used for tower-type or beam-down type solar thermal power generation will be described.

<Heliostat>
The heliostat 1 is of a multi-mirror type in which the reflection function is distributed to four mirrors 2 as mirror elements. A bar 4 is erected on the base 3 of the heliostat 1 (may be erected in the ground), and a box 6 of the solar light detection device 5 is obliquely fixed to the upper end thereof. The direction in which the box 6 is located is the direction in which the sunlight L is desired to be reflected, and a target that focuses the sunlight L exists at a position away from the box 6 side.

  A support column 7 is provided on the side of the base 3 opposite to the bar 4, and a first drive unit 8 is provided on the upper end thereof. The first drive unit 8 is provided with a first shaft 9 that is parallel to the rotation axis of the earth and has a predetermined angle with respect to the ground. The first shaft 9 is rotatable by the first driving unit 8 in the ascending direction A (see FIG. 2) related to the diurnal motion around the axis. Since the first shaft 9 is provided, the heliostat 1 is an equator ritual.

  A U-shaped frame 10 is fixed to the tip of the first shaft 9. A second shaft 11 passes through the flange on both sides of the frame 10 in a direction perpendicular to the first shaft 9. The second shaft 11 is a metal pipe, and both sides protrude to the outside of the flange. Between the frame 10 and the second shaft 11, there is provided a second drive unit 12 that rotates the second shaft 11 in the declination direction B (see FIG. 2) related to the seasonal motion.

  Another support pipe 13 penetrates in the orthogonal direction at both ends of the second shaft 11 protruding outward from the frame 10. The second shaft 11 and the support pipe 13 form an H shape, and the mirrors 2 are respectively attached to the ends of the support pipe 15 at the four corners by metal fittings 14. The mirror 2 is circular with a diameter of 50 cm, and its surface is a concave spherical surface corresponding to the focal length to the target.

  A sensor mirror 16 is provided on the second shaft 11 inside the frame 10 via a pair of brackets 15. The sensor mirror 16 is a horizontally long rectangle and has a flat surface.

  The sunlight L reflected by the sensor mirror 16 is received by the sunlight detection device 5. The sunlight detection device 5 is located between the sensor mirror 16 and a target (not shown). Therefore, when the sunlight L from the sensor mirror 16 is reflected so that it is always received by the sunlight detection device 5, the sunlight L always goes to the target ahead of the sunlight detection device 5. The angles of the four mirrors 2 are adjusted in advance so that the sunlight L reflected by the sensor mirror 16 is used as an optical axis, and the light is completely overlapped as a single condensing spot at the focal length position on the optical axis. .

<Sunlight detection device>
Next, the structure of the sunlight detection device 5 will be described. The box 6 of the solar light detection device 5 has a hollow shape having a cylindrical inner surface, and has a circular introduction surface 17 and a bottom surface 18 at both ends. The box 6 has a diameter of 45 mm and a length of 60 mm, and is fixed obliquely with the introduction surface 17 down.

  A circular and tapered introduction hole 19 is formed in the center of the introduction surface 17. The introduction hole 19 is covered from the outside with a transparent cover 24 made of resin. On the bottom surface 18 of the box 6, a pair of light detection sensors 20a, 20b, 21a, 21b are discretely arranged in an orthogonal cross shape. The light detection sensors 20a, 20b, 21a, and 21b have a small square area size. The photodetection sensors 20a, 20b, 21a, and 21b may have a shape other than a square and a non-long shape in which the length dimension d in each direction X and Y is less than twice the width dimension.

  The two light detection sensors 20a and 20b are opposed to each other in the direction X related to the red meridian direction A of the heliostat 1, and the other two light detection sensors 21a and 21b are arranged in the direction Y related to the declination direction B. Opposite.

  A circular spot P of sunlight L introduced straight from the introduction hole 19 is formed at the center of the bottom surface 18 of the box 6, and each of the light detection sensors 20 a, 20 b, 21 a, 21 b has an outer edge of the spot P. It is arranged at a position to pass. In the present embodiment, the light detection sensors 20a (21a) and 20b (21b) facing each other are arranged so that the interval is related to the size (effective diameter) R of the spot P.

  Since the introduction hole 19 is circular and the spot P of sunlight L is circular with an effective diameter R, the arrangement of the light detection sensors 20a, 20b, 21a, and 21b is easy. An interval D that is equal to or larger than the effective diameter R of the spot P is secured between the light detection sensors 20 a, 20 b, 21 a, 21 b and the inner surface of the box 6.

  In the state where the spot P is at the center (neutral position) of each of the light detection sensors 20a, 20b, 21a, and 21b, the light reception between the pair of light detection sensors 20a, 20b and 21a, 21b in both the direction X and the direction Y The amounts are equal and the outputs from the light detection sensors 20a, 20b, 21a, 21b are equal. Each of the light detection sensors 20a, 20b, 21a, and 21b can be discretely arranged at a predetermined interval, and as shown in FIG. 5, the spot P is all detected with the spot P in the neutral position. It is preferable that the sensors 20a, 20b, 21a, and 21b are arranged so as to reach a part of the light receiving area (upper limit interval).

  Outputs from the light detection sensors 20a, 20b, 21a, and 21b are detected by the control units 22 and 23. When the outputs of the pair of light detection sensors 20a, 20b, 21a, and 21b are equal, the differential output between the sensors is zero. It becomes. In this case, since the reflected light is directed in a predetermined direction, no drive signal is output to the first drive unit 8 and the second drive unit 12.

  When the spot P of the sunlight L from the introduction hole 19 is shifted from the neutral position and the outputs of the light detection sensors 20a, 20b, 21a, 21b are different, the control units 22, 23 detect the state, A drive signal is output to the first drive unit 8 and the second drive unit 12, and the mirror 2 of the heliostat 1 is rotated to perform feedback control so as to correct the output uneven state.

  As shown in FIG. 4, the spot P can be controlled by receiving sunlight L if the outer edge of the spot P hits only a part of the terminals inside the light detection sensors 20a, 20b, 21a, 21b. . The angle formed by the sunlight L received by the outermost terminals on both sides in each direction X and Y is the capture angle θ. If the upper limit interval necessary for detecting the neutral position of the spot P is secured, the capture angle θ may be increased as the terminals outside the light detection sensors 20a, 20b, 21a, and 21b are located more outward. it can.

  Further, even when light is received by the outermost terminals of the light detection sensors 20 a, 20 b, 21 a, and 21 b, the distance between the light detection sensors 20 a, 20 b, 21 a, and 21 b and the inner surface of the box 6 is not less than the diameter of the spot P. Since D is secured, the spot P does not hit the inner surface and irregularly reflects and does not adversely affect the light receiving state of the light detection sensors 20a, 20b, 21a, 21b.

  The above control method will be described by taking the direction X related to the meridian direction A of the heliostat 1 as an example. FIG. 9 is an explanatory diagram showing the output of the light detection sensor. FIG. 10A schematically shows the relationship between the position of the optical center of gravity of the spot P in the X direction and the output of the light detection sensors 20a and 20b. It is. Note that the effective diameter of the spot P on the light receiving surface of the light detection sensor is R.

  For example, as shown in FIG. 7, when the orientation of the sensor mirror 16 is deviated from the normal position when the heliostat 1 is first controlled, the sunlight L reflected by the sensor mirror 16 is reflected by the sunlight detection device. 5 is not introduced straight from the introduction hole 19, and the spot P is shifted as shown in FIGS. 9B, 9C, and 9D. Then, the outputs from the light detection sensors 20a and 20b are also uneven, and outputs as shown in the areas (b), (c), and (d) of FIG. . Further, if the difference between the two outputs is taken, as shown in FIG. 10B, the region (b) in the vicinity of the neutral position is sensitive to deviation. The range d of this region is determined by the width in the X direction of each of the optical sensors 20a and 20b, the distance between the optical sensors, and the effective diameter R of the spot P.

  In the areas (c) and (d) where the deviation of the spot P is large, the light detection sensor 20b is not hit by the spot P, but the light sensor 20a can detect the rough position of the spot P by detecting the spot P. it can.

  Therefore, the control unit 22 detects the respective states based on the outputs and differential outputs of the light detection sensors 20a and 20b, outputs a signal to the first drive unit 8, rotates the heliostat 1, and the sensor mirror 16 Rotate to the correct position. Then, as shown in the area (a) of FIG. 9A and FIG. 10A, the outputs from the respective light detection sensors 20a and 20b become equal, and the sunlight L reflected by the heliostat 1 is detected. It passes through the sensor 5 and is correctly guided to the target ahead.

  Once controlled by the light detection sensors 20a and 20b, since the spot P is in the vicinity of the neutral position, the position of deviation is detected at a high magnification, and the sun is tracked as it is to maintain the correct state. Similarly, the sun can be tracked in the Y direction related to the declination axis. Even when the spot P deviates from the vicinity of the neutral position, as described above, the spot P is neutralized based on the outputs of the light detection sensors 20a, 20b, 21a, and 21b, their differential, addition calculation, and the like. Feedback control can be performed so as to converge and maintain near the position.

  According to the present embodiment, the small area photodetection sensors 20a, 20b, 21a, and 21b are used, which is advantageous in terms of cost. Accordingly, even when a solar thermal power plant is constructed using a large number of heliostats 1, the overall cost can be reduced. In the present embodiment, the equatorial ritual heliostat 1 is taken as an example, but a theodolite heliostat may be used.

DESCRIPTION OF SYMBOLS 1 Heliostat 5 Light detection sensor 6 Box 18 Bottom surface 19 Introduction hole 20a, 20b, 21a, 21b Light detection sensor 22, 23 Control part L Sunlight A Red longitude direction B Declination direction X Direction related to the red longitude direction Y Red Direction related to latitude direction P Spot D Interval

Claims (5)

A pair of photodetection sensors that form a sunlight introduction hole in the center of one side of the box and face the inner bottom side opposite to the one side of the box in two directions perpendicular to each other in a cross shape and sandwiching the center of the bottom side. And a control unit that outputs a signal to the outside so that the amount of light received by the pair of light detection sensors in each direction is equalized by the spot of sunlight introduced from the introduction hole. And
The light detection sensor is provided at a position where the outer edge of the spot of sunlight introduced from the introduction hole has a length in each direction,
A solar light detecting device, wherein an interval equal to or greater than a diameter of a solar light spot is provided between the light detecting sensor and the inner surface of the box.   The length of the photodetection sensor in each direction is a non-long shape that is less than twice the width, and the interval between the photodetection sensors facing each other is arranged in association with the size of the spot of sunlight. The solar light detection device according to claim 1.   The solar light detection device according to claim 1 or 2, wherein the box has a shape having a cylindrical inner surface, and the introduction hole is circular.   The two orthogonal directions in which the light detection sensor is disposed are a direction related to the declination direction of the equatorial ritual heliostat and a direction related to the ecliptic direction. Solar detection device.   The sunlight detecting apparatus according to claim 4, wherein the sunlight introduced from the introduction hole is sunlight reflected by the reflecting surface of the heliostat.

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