JPH0222857B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a solar tracking and concentrating device, and is particularly applicable to solar heat utilization equipment such as solar thermal power generation equipment, concentrating photovoltaic power generation equipment, and industrial high-temperature heat source supply equipment. The present invention relates to a solar tracking and condensing device that performs light condensing and tracking using a large number of plane mirrors (heliostats) suitable for the condensing device.

[Background of the invention]

A conventional solar tracking and condensing device that tracks and focuses the sun using a large number of plane mirrors, as shown in Figure 1, has a sun pointing bar 1, a mirror fixing bar 2, and an azimuth that has an inclination angle equal to the latitude of the plane mirror installation location. It has a solar motion tracking mechanism composed of an angular rotation axis 5, an elevation adjustment bar 7, a plane mirror rotation table 6, etc. This tracking mechanism uses an elevation adjustment bar 7 to adjust the plane in which the sun moves during the day when the sun is viewed from the ground (the angle formed by the plane in which the sun moves relative to the horizontal plane is defined as the elevation angle) and the plane in which the sun direction bar 1 moves. The direction of movement of the sun is tracked and focused by the constant rotation of the azimuth rotation axis 5. For this purpose, the azimuth rotation axis 5 must be placed precisely in the due south direction, and the line segment connecting its tip a and the plane mirror rotation center b must coincide with the light collection direction.

Therefore, the installation and adjustment work of the device is complicated, and the drive mechanism is complicated. Further, since the azimuth rotation axis 5 and the rotation axis direction of the plane mirror rotary table do not match, there is a drawback that the movable range of the plane mirror is limited. For this reason, when urgently stopping light collection and retracting the mirror, such as when the heat collection temperature rises abnormally, it is difficult to completely shift the light from the heat collection part due to the limited movable range of the plane mirror. There are cases. Further, the slider 10 has a structure in which it slides on the mirror fixing bar 2, and is installed outdoors. Therefore, if the slider 10 is exposed to the wind and rain and is not sufficiently lubricated, rust etc. will occur and the slider 10 will not move smoothly.

In addition, even after installing a light concentrator, the positional relationship of the solar orientation bar 1 or the azimuth rotation axis 5 may become out of order due to changes over time such as wear and tear of the ground subsidence drive mechanism, causing the light concentration to shift. However, there is a drawback that readjustment of the device is required.

[Purpose of the invention]

The purpose of the present invention is to provide a solar tracking concentrator that uses a large number of plane mirrors (heliostats) to condense light. To provide a solar tracking and condensing device which has a simple structure, does not shift the focus even when the light is focused, does not require adjustment of a condensing and tracking mechanism.

A conventional plane mirror sun tracking mechanism has an azimuth rotation axis with an inclination angle equal to the latitude of the installation location, a rotation axis for elevation adjustment, and a rotation of the support part of the mirror itself so that the plane mirror follows the tracking drive mechanism. The axis of rotation of the driving part of the mirror does not coincide with the axis of rotation of the support part of the mirror itself. Therefore, a slider portion is required to eliminate the discrepancy in movement between the drive mechanism and the mirror support. Therefore, the rotation range of the drive mechanism is limited, and the movable range of the mirror is narrow. In addition, even if the relative positional relationship of each part of the condensing device changes due to aging, etc., the driving part of the drive mechanism remains as it is and rotates at a constant rotation, so the condensation will shift and the drive mechanism will need to be adjusted. .

[Summary of the invention]

The present invention installs a directional reflecting mirror at a light condensing position,
By detecting the reflected light and the incident light from the sun using a photodetector installed on the plane mirror, the relative position of the mirror itself with respect to the direction of the sun and the direction of light collection is calculated, and based on the results, the plane mirror is It is designed to be driven. Therefore, the relative position of the mirror is always detected and the position of the mirror is corrected by feedback drive in the correct direction, so there is no need for adjustment even if the relative positional relationship of each part of the condensing device changes due to aging or the like.
Furthermore, since it is possible to match the rotation axis of the drive portion of the mirror with the rotation axis of the support portion of the mirror itself, the structure of the drive mechanism is simple and the condensing device can have a large movable range of the mirror.

[Embodiments of the invention]

The present invention will be explained below with reference to Examples.

FIG. 2 shows an embodiment of the present invention, in which a hemispherical mirror 19 having a light incident direction detector is installed on a plane mirror 4,
A light incident direction detector 29 is provided at the light focusing position. The hemispherical mirror 19 having a light incident direction detector and the light incident direction detector 29 at the condensing position both detect the light incident direction based on the output ratio of two photodetectors arranged at different angles. Based on this signal, the drive of the plane mirror 4 is controlled by an azimuth rotation axis drive motor 21 and an elevation angle rotation axis drive motor 22. According to this embodiment, even if the relative positional relationship of each part of the light collecting device changes when the light collecting device is installed or due to changes over time, the focused light does not shift, and there is no need to adjust the light focusing and tracking mechanism.

FIG. 3a shows the configuration of a light direction detector 29 installed inside a hemispherical mirror 19. A value obtained by dividing the outputs of two photodetectors 11 and 12 installed at different angles by a divider 14 is output. Figure b shows the output ratio for various values of the solar altitude angle α (for simplicity, Figure b assumes that the sun direction and the normal to the detection surfaces of the two photodetectors are included in the same plane). From the same figure b, the direction of incidence of the sun (high angle α) is determined from the output ratio.
can be found. Furthermore, as shown in FIG.
Then, the outputs of the photodetectors 11 and 13 are input to the divider 15.

By inputting these output ratios into the calculator 18, the direction of the sun (altitude angle α and azimuth angle β) can be calculated.

FIG. 5 shows another example of the light direction detector 29, with the fourth
This is a light collection accuracy inspection device for detecting reflected light from a plane mirror using the detector shown in the figure. photodetector 12',
By further adding 13', a wide range of light can be detected. The sunlight reflected by the plane mirror 4 is detected by the photodetectors 11 to 13, 13', and the output thereof is as follows.
The signals are input to each of the dividers 14 to 17, and an output ratio is calculated. This output ratio is input to the computer 18, the direction of the reflected light is calculated, and the focusing deviation of the plane mirror is detected. This focusing accuracy inspection device directly detects the reflected light from the plane mirror, so systematic errors in measurement are less likely to occur, and since there are no moving parts, no mechanical adjustment is required, making measurement simple.

FIG. 6 shows another embodiment of the present invention, in which the light incident direction detector shown in FIG. 4 or 5 is installed on each plane mirror. In addition, a hemispherical reflecting mirror 19 is installed on the plane mirror, and a directional reflecting mirror 30 is placed at the condensing position.
(For example, a right-angled conical cylinder or prism whose inner surface is coated with silver) is installed. A portion of the light reflected over a wide area by the hemispherical reflector is reflected by the directional reflector and returns to its original position. A detector detects the reflected light that returns to its original position and the direct incident light from the sun, and the direction of each light ray is calculated. As described above, the light incident direction detection device composed of the photodetector fixed on the plane mirror calculates the direction of incidence of the sun on the plane of the plane mirror and the direction of light condensation on the heat collector. In the present invention, a light incident direction detector 19 is constructed by fixing a photodetector to the surface of a hemispherical reflecting mirror. The calculation results of the sun's incident direction and the light condensing direction with respect to the plane of the plane mirror are input to the plane mirror drive control device 20, and the normal direction of the plane mirror is placed in a position equally divided between the sun's incident direction and the collector's condensing direction. The azimuth angle rotation axis drive motor 21 and the elevation angle axis drive motor 22 are driven. In this way, the concentrator detects the reflected light from the direction of the collector and the direct incident light from the sun, calculates the relative position of the mirror itself with respect to these light rays, and ensures that the mirror is always positioned in the correct direction. Since the correction is driven by feedback, even if the relative positional relationship of each part of the device changes during installation or due to aging, the light is focused correctly and there is no need for adjustment.
In addition, the directional reflecting mirror 23 has the property of always reflecting light in the direction of incidence, and the influence of diffuse reflection from surrounding objects is small, so even if the number of plane mirrors increases, the light can be focused correctly. . Also,
Since the driving rotation axis of the plane mirror and the support rotation axis of the plane mirror itself are the same, the plane mirror has a wide movable range, and even when it is necessary to urgently evacuate the condensed light, the plane mirror can be easily condensed and evacuated. . Further, since the drive rotation axis and the support rotation axis of the plane mirror are the same, the structure is simple and there is no sliding part, which has the effect of facilitating lubrication of the drive part.

FIG. 7 shows another embodiment of the present invention in which the light beam direction detection circuit and plane mirror drive control device of the embodiment of FIG. 6 are further implemented. On the surface of a hemispherical reflecting mirror, four pairs of photodetectors 11 and 12 are installed, making a total of eight photodetectors. Each set of photodetectors further forms a pair with the opposite set, and is used for elevation angle drive control and azimuth angle drive control, respectively. The outputs of the opposite sets of photodetectors 11 and 12 are input to dividers 14 and 15, respectively. Furthermore, the outputs of photodetectors 11 and 12 are NAND
It is input to the gate 23, and a zero output voltage is always output unless both inputs are at zero voltage. This NAND gate is further input to the set terminal of the changeover switch, and is switched to the divider 14 side whenever the outputs of the photodetectors 11 and 12 are both non-zero. The output of the changeover switch is connected to the input side of a differential amplifier 26, the output of which is connected to the drive motor 22 for elevation control and to the drive motor 21 for azimuth control. Therefore, as shown in Figure b, the divider output is larger on the side where the angle with respect to the normal n of the plane mirror is larger (in the figure, the incident light 27 side), so the differential amplifier output becomes positive (Figure a The mirror rotates in the direction in which the normal line of the plane mirror is located at the center of the incident beams 27 and 28 (the rotation is determined so that the differential amplifier has a positive output and the rotation is clockwise as seen from the motor side). In addition, if both incident light beams are incident on only one side, the pair of photodetectors on the opposite side both have zero output, so the NAND gate 23
As a result, a unit voltage is output, the changeover switch 24 is switched to the ground side, and zero voltage is input to the differential amplifier 26, so that a larger drive voltage is applied to the drive motor. In this way, since a drive voltage corresponding to the angular deviation of the plane mirror is applied to the drive motor, the tracking drive operation of the plane mirror is smooth and the response speed is fast. In addition, since the output of each pair of photodetectors is divided by a divider to normalize the output, the magnitude of the output is similar to that of direct incident light from the sun and reflected light from a directional reflector. This has the effect that the direction of incidence can be detected without any problem even if there is a large difference in the direction of incidence.

FIG. 8 shows another embodiment of the present invention, in which a directional light source 26 such as a laser beam is installed at a condensing position, and the directional light beam is directed toward a light detection unit 19 fixed at the center of a plane mirror.

When using a directional reflector as shown in Figure 6, a relatively large hemispherical reflector is required in order for the light source reflected by the reflector to have enough intensity to be detected. . However, when a laser light source is used, only a photodetector needs to be installed at the center of the reflecting mirror, and there is no significant difference in intensity between the light and the light that enters directly from the sun.

As described above, according to the present invention, the incident direction of a light beam can be easily detected by using photodetectors installed at different angles and inputting the information to a divider. In addition, according to another embodiment in which the present invention is applied to a condensing accuracy inspection device for a plane mirror, since the reflected light of the plane mirror is directly detected, systematic errors in measurement are less likely to occur, and since there are no moving parts,
This eliminates the need for mechanical adjustment and has the effect of simplifying settings. In another embodiment of the present invention, a hemispherical reflector is installed on the plane mirror, the light is reflected to the directional reflector in the condensing device, and the light reflected by the directional reflector is directly connected to the condensing device. The light incident from the sun is detected, and the output from each photodetector is input to a divider. The output of each divider is input to a differential amplifier along with the output of the photodetector on the opposite side, and the output is used to control the rotary shaft drive motor. According to this embodiment, since a drive voltage corresponding to the angular deviation of the plane mirror is applied to the rotary shaft drive motor, the tracking drive operation of the plane mirror is smooth and the response speed is fast. In addition, since the output of each pair of photodetectors is normalized by dividing it by a divider, the magnitude of the output is similar to that of direct incident light from the sun and reflected light from a directional reflector. This has the effect of allowing the direction of incidence to be detected even when there is a large difference.
In addition, the position of the mirror is always driven by feedback,
Since it is corrected to the correct position, even if the relative positional relationship of each part of the device changes during installation or due to aging, the light is focused correctly and there is no need for adjustment. In addition, since the driving rotation axis of the plane mirror and the support rotation axis of the plane mirror itself are the same, the plane mirror has a wide movable range, and even when it is necessary to urgently evacuate the condensed light, the plane mirror can easily perform the condensing and retreating operation. There are effects that can be done. Further, since the drive rotation axis and the support rotation axis of the plane mirror are the same, the structure is simple and there is no sliding part, which makes it easy to lubricate the drive part.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of a conventional embodiment, Fig. 2 is a schematic diagram of the present invention, Fig. 3 is a schematic diagram showing the principle of a photodetector of the present invention, and Fig. 4 is a schematic diagram of the present invention. Of these, FIG. 5 is a schematic diagram showing the configuration of a photodetector, FIG. 5 is a schematic diagram of another embodiment of the present invention applied to a condensing accuracy inspection device for a plane mirror, and FIG. 6 is a schematic diagram showing another embodiment of the present invention. Fig. 7 is a schematic diagram of an example in which the outputs of four photodetectors are input to a divider, and the outputs are input to a differential amplifier. A schematic diagram of an example in which the drive motor is controlled using the output, and FIG. 8 is a schematic diagram of an example in which a laser light source is used as the light source from the condenser. 1... Sun pointing rod, 2... Plane mirror fixed axis, 4...
...Plane mirror, 5...Azimuth drive shaft, 6...Plane mirror main body support rotating shaft, 8...Heat collecting tube, 11, 12...Photodetector, 14...Divider, 16...Calculation for calculating solar direction device, 19... hemispherical reflector and light incident angle direction detector, 20... plane mirror drive control device, 21...
Azimuth angle rotation axis drive motor, 22...Elevation angle rotation axis drive motor, 23...NAND gate, 24...
...Selector switch, 26...Laser light source, 30
...Directional reflector.

Claims (1)

[Scope of Claims] 1. A concentrating device for solar heat utilization equipment in which light from the sun is condensed by a plane mirror, comprising: an azimuth drive rotating shaft that supports the plane mirror and adjusts the azimuth of the plane mirror; an elevation drive rotation axis that adjusts the elevation angle of the plane mirror; a hemispherical reflecting mirror provided on the plane mirror; a directional reflecting mirror provided at a condensing position; and a directional reflecting mirror provided on the hemispherical reflecting mirror. a plurality of light incident direction detectors that detect the light incident direction based on the output ratio of two photodetectors arranged at different angles; A solar tracking condensing device having a plane mirror drive control device that drives and controls the azimuth angle drive rotation axis and the elevation angle drive rotation axis based on the incident direction of the reflected light from the directional reflecting mirror of the light position.