JP3989263B2 - A pyranometer using multiple quantum sensors - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pyranometer that measures the intensity of solar radiation, and more particularly to a pyranometer that uses a plurality of quantum sensors and a method for calculating the solar radiation intensity using the pyranometer.
[0002]
[Prior art]
Many power generation systems have become widespread in the field of photovoltaic power generation, but a cheap and stable solar radiation meter is required for continuous monitoring of performance such as the output of these systems.
[0003]
In particular, for residential power generation systems, the direction of the roof on which solar cells are installed is expected in all directions, and in order to estimate the solar radiation intensity on each surface, first, the solar radiation intensity data on each surface is indispensable. is there. Therefore, a large number of inexpensive pyranometers are desired.
[0004]
In addition to the solar power generation field, there is a demand for a cheap and stable pyranometer in fields such as weather forecasting, agriculture, and architecture.
[0005]
Currently, the most popular pyranometers use the thermal type as a sensor. The basic configuration of the thermal type sensor is to measure a temperature rise depending on the solar radiation intensity of the heat-receiving plate painted black. In this case, it has been found that deterioration of about 1% per year occurs due to deterioration of the black paint.
[0006]
In addition, a pyranometer using the above-described structure is usually an expensive device. Therefore, for economic reasons, an inexpensive Si (silicon) sensor alone has been adopted as a sensor for a pyranometer, but it is pointed out that the sensitivity of the pyranometer in this case greatly increases the measurement error due to the spectral error. ing.
[0007]
As described above, the currently used pyranometers use the thermal type and the single Si sensor, but have the following problems.
[0008]
That is, in the case of a thermal pyranometer, in addition to being expensive, the sensitivity itself changes over time, the zero offset value is large in principle, there is a tilt characteristic, and the response speed is delayed. There are some disadvantages.
[0009]
Further, in the case of a Si sensor single-type pyranometer, the solar radiation measurement device itself is inexpensive, but as will be apparent from FIGS. 1 and 2 described later, the solar radiation distribution and the Si spectral characteristics do not match in terms of wavelength. Therefore, there are drawbacks such as a very large spectral error.
[0010]
Here, FIG. 1 is a diagram showing the solar radiation spectrum, and FIG. 2 is a diagram showing the spectral sensitivity characteristics of the Si sensor and the InGaAs sensor.
[0011]
The above disadvantages are fatal for monitoring the system output for photovoltaic power generation. In particular, in the case of a thermal type pyranometer, the fact that the pyranometer device itself is expensive is a great economic burden when it is adopted in many power generation systems. In addition, the secular change in the output of the photovoltaic system is considered to be minimal, and the fact that the sensor for monitoring this changes over time detracts from the significance of monitoring. Furthermore, each element including the solar cell constituting the photovoltaic power generation system includes an inverter and the like, and the response is very fast. In particular, it is almost impossible to faithfully monitor with a thermal sensor.
[0012]
Specifically, since cloudy days with unstable solar radiation appear throughout the year, measurement of the output characteristics of a power generation system with a quick response is very important in the case of a thermal pyranometer with a slow response speed. Results with errors are introduced.
[0013]
[Problems to be solved by the invention]
In view of the above circumstances, an object of the present invention is to provide a pyranometer that eliminates the above-mentioned drawbacks.
[0014]
[Means for Solving the Problems]
The object of the present invention is to provide the first quantum sensor, the second quantum sensor provided with the optical filter, the first output voltage from the first quantum sensor, A solar radiation meter that receives a second output voltage from the second quantum sensor and calculates a solar radiation intensity, wherein the calculation means records a first coefficient K1. A recording unit, a second recording unit that records the second coefficient K2, and a third recording unit that records the third coefficient K3,
[Formula 1]
G = K1 · E1 + K2 · E2 + K3
(Here, G refers to solar radiation intensity, and E1 and E2 refer to the first output voltage and the second output voltage, respectively.)
The solar radiation intensity is calculated from the above relationship, and this is achieved by the first aspect of the pyranometer.
[0015]
In addition, the object is to provide a first quantum sensor, a second quantum sensor having an optical filter, and a first output from the first quantum sensor in a pyranometer using a quantum sensor. A solar radiation meter that receives a voltage and a second output voltage from the second quantum sensor and calculates a solar radiation intensity, wherein the calculation means records a fourth coefficient K4. A fourth recording section, a fifth recording section for recording a fifth coefficient K5, and a sixth recording section for recording a sixth coefficient K6;
[Formula 2]
G = K4 · E1 + K5 · R + K6
(Here, E1 and E2 are referred to as the first output voltage and the second output voltage, respectively, and R = E1 / E2.)
The solar radiation intensity is calculated from the above relationship, and this is achieved by the second aspect of the pyranometer.
[0016]
Furthermore, the above object is to provide a first quantum sensor, a second quantum sensor having a photosensitive wavelength band different from that of the first quantum sensor, and the first quantum sensor in a pyranometer using a quantum sensor. A solar radiation meter comprising a first output voltage from the mold sensor and a second output voltage from the second quantum sensor to calculate the solar radiation intensity, wherein the calculation means comprises: A first recording unit that records one coefficient K1, a second recording unit that records a second coefficient K2, and a third recording unit that records a third coefficient K3;
[Formula 3]
G = K1 · E1 + K2 · E2 + K3
(Here, G refers to solar radiation intensity, and E1 and E2 refer to the first output voltage and the second output voltage, respectively.)
This is achieved by the third aspect of the present invention which is a pyranometer that calculates the solar radiation intensity from the relationship.
[0017]
Still further, the object is to provide a first quantum sensor, a second quantum sensor having a photosensitive wavelength band different from that of the first quantum sensor, and the first quantum sensor using a quantum sensor. A solar radiation meter comprising: a first output voltage from a quantum sensor and a second output voltage from the second quantum sensor to calculate solar radiation intensity, wherein the calculation means comprises: A fourth recording unit for recording the fourth coefficient K4, a fifth recording unit for recording the fifth coefficient K5, and a sixth recording unit for recording the sixth coefficient K6.
[Formula 4]
G = K4 · E1 + K5 · R + K6
(Here, E1 and E2 are referred to as the first output voltage and the second output voltage, respectively, and R = E1 / E2.)
This is achieved by the fourth aspect of the present invention which is a pyranometer that calculates the solar radiation intensity from the relationship.
[0018]
In the first and second aspects of the present invention, the first and second quantum sensors are Si sensors.
[0019]
In the first and second aspects of the present invention, the optical filter is a cut-off filter.
[0020]
In the third and fourth aspects of the present invention, the first quantum sensor is a Si sensor, and the second quantum sensor is an InGaAs sensor.
[0021]
According to a preferred aspect of the solar radiation meter of the present invention, the solar radiation meter further includes display means for displaying a calculation result by the calculation means.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of a solar radiation meter and a solar radiation intensity calculation method using the solar radiation meter according to the present invention will be described with reference to the drawings.
[0031]
FIG. 1 is a diagram showing a spectrum of spectral solar radiation intensity depending on the solar altitude. From FIG. 1, it can be seen that the spectral distribution of solar radiation changes due to changes in atmospheric conditions, for example, solar altitude.
[0032]
The present invention is a pyranometer that uses at least two quantum sensors, and each quantum center needs to use sensors having different photosensitive wavelength ranges.
[0033]
Specifically, there are roughly two types of quantum type sensors employed by the pyranometer according to the present invention. The first type uses two similar types of quantum sensors, one of which uses an optical filter and the other of which uses no optical filter. is there. As a second type, a quantum sensor using two different photosensitive wavelength ranges is used.
[0034]
In the first type, the pyranometer according to the present invention is not limited to this, but uses two Si sensors, and one sensor is equipped with a cutoff filter that transmits longer wavelengths than 670 nm. The other sensor is composed of a Si sensor having inherent spectral characteristics. In this case, a sensor having a cutoff filter measures solar radiation of 670 nm or more, and an original Si sensor not having a filter can measure solar radiation in the photosensitive wavelength band (0.3 to 1.1 μm). In addition, although the filter which permeate | transmits light with a long wavelength of 670 nm or more was illustrated here as a characteristic of a cut-off filter, this invention is not limited to the said characteristic.
[0035]
In the second type, the pyranometer according to the present invention includes two quantum sensors having different photosensitive wavelength bands, specifically, an Si sensor (photosensitive wavelength band 0.3 to 1.1 μm) and InGaAs (photosensitive wavelength band). 0.9 to 1.8 μm).
[0036]
FIG. 2 shows the spectral sensitivity curves of the two types of sensors described above that can be used in the present invention. It can be seen that solar radiation can be detected in a wide band as compared with the case of the Si sensor alone.
[0037]
3 and 4 are schematic cross-sectional views of the pyranometer according to the present invention. FIG. 3 shows a first type of pyrometer 10 of the present invention. A diffusion plate 20 for taking in solar radiation is disposed on the upper surface of the solar radiation meter 10. The function of the diffusing plate 20 satisfies the angle characteristics of the pyranometer 10 and is not particularly limited as a material, but is preferably made of Teflon.
[0038]
Further, the pyranometer 10 is equipped with two Si sensors 30 and 40 that are the same type of quantum sensors so as to face the center of the plate 20 below the diffusion plate 20. An optical filter 50 is disposed on the upper surface of one of the two quantum sensors. As described above, the optical filter 50 is preferably a cutoff filter that transmits a long wavelength side from a predetermined wavelength. Specifically, R66 (manufactured by Hoya Glass) or the like can be used.
[0039]
The Si sensor 30 including the optical filter 50 senses light only in the long wavelength region. Then, the Si sensor 40 having no optical filter senses light in the wavelength range of 0.3 to 1.1 μm, and the Si sensor 30 and 40 assigns the photosensitive wavelength range to the roles, thereby calculating a calculation method to be described later. Accordingly, it is possible to measure the solar radiation intensity.
[0040]
As for the place where the solar radiation meter 10 is used, the environment where solar radiation intensity is measured is -20-40 degreeC normally. Therefore, in order to eliminate an adverse effect due to dew condensation or the like inside the pyranometer, the pyranometer 10 according to the present invention preferably further includes a desiccant container 60 containing a desiccant such as silica gel.
[0041]
The output voltage of each sensor can be taken out independently, taken into calculation means 70 comprising a CPU and a memory, and the solar radiation intensity can be calculated by a calculation method described later. Although FIG. 3 shows a mode in which the CPU and the like are mounted inside the solar radiation meter, those skilled in the art can calculate the solar radiation intensity using an external CPU using a connector (not shown). Can understand.
[0042]
Furthermore, the pyranometer 10 according to the present invention preferably includes a level 80. By having this level 80, it is possible to measure the solar radiation intensity while always checking the horizontal state, and to eliminate the influence of the angle on the measurement of the solar radiation intensity.
[0043]
The solar radiation intensity calculated in this way is displayed on an external display device (not shown) via the output connector 90.
[0044]
A second type of pyranometer 100 according to the present invention will be described below. Except for the sensor portion, the solar radiation meter 10 is the same as the first type solar radiation meter 10 described above, and thus the description of the solar radiation meter 100 is omitted.
[0045]
FIG. 4 shows a schematic cross-sectional view of a second type of pyranometer 100, which is composed of two quantum sensors having different photosensitive wavelength bands. Specifically, FIG. 4 shows a sensor comprising a combination of a Si sensor 120 having a photosensitive band of 0.3 to 1.1 μm and an InGaAs 130 having a photosensitive band of 0.9 to 1.8 μm (photosensitive wavelength). See Figure 2 for bandwidth).
[0046]
In addition to the configuration of the Si sensor with or without the optical filter described above, a pyranometer that can follow the spectral characteristics of solar radiation that changes according to atmospheric conditions is realized by adopting a configuration of two quantum sensors with different photosensitive bands. .
[0047]
Next, a calculation method for calculating the solar radiation intensity from the output voltage obtained by the above-described solar radiation meters 10 and 100 according to the present invention will be described.
[0048]
The first calculation method is a method of calculating on the basis of a sensitivity constant.
[0049]
Assuming that the output voltage of a pyranometer configured with a conventional Si sensor alone is E and the solar radiation intensity is G,
G = K * E (1)
There is a relationship. Here, K is a sensitivity constant. In the conventional method, when a single Si sensor is used, K is handled as a constant. However, as shown in FIG. 8 described later, the sensitivity constant is not constant with respect to the solar radiation intensity.
[0050]
Assuming that the output voltages from the respective sensors from the two types of pyranometers 10 and 100 according to the present invention are E1 and E2, and the sensitivity constants are K1 and K2, respectively, the obtained solar radiation intensity G is as follows: It is expressed in
[0051]
G = E1 * K1 + E2 * K2 + K3 (2)
That is, accurate measurement is possible by increasing the output information to two. More specifically, the spectral distribution of global solar radiation is largely divided into factors that change in all wavelength regions (solar altitude, aerosol, clouds, etc.) due to atmospheric conditions, and factors that mainly change only in the long wavelength region (falling moisture). Separated. Therefore, if the solar radiation meter using two quantum sensors having different sensitivity bands is used, it is possible to follow the spectral characteristics of solar radiation that changes depending on atmospheric conditions.
[0052]
Then, it is necessary to determine constants K1, K2, and K3 on the right side of Expression (2). This method uses outdoor light in various atmospheric conditions, and the left side is used to determine the exact solar radiation intensity with a thermal solarimeter with uniform spectral characteristics, and at the same time, the output voltages of two quantum sensors are measured under the same conditions. To do. Applying this result to equation (2), three unknown constants can be obtained by the method of least squares.
[0053]
Using the equation (2), the coefficients were calculated as K1 = 1.442, K2 = 1.530, and K3 = −1054, respectively, as an example.
[0054]
Unlike equation (2), the solar radiation intensity can be calculated by a second calculation method that uses a constant as a function of the output voltage ratio R of the two quantum sensors.
[0055]
Specifically, as described above, when the output voltages E1 and E2 from each sensor are used, the output ratio R is:
R = E1 / E2 (3)
It can be expressed as. The solar radiation intensity G is
G = K4 * E1 + K5 * R + K6 (4)
And given.
[0056]
By using equation (4), for example, K4 = 1.890, K5 = 66130, and K3 = −20398 were obtained.
[0057]
Equations (2) and (4) used in the above two calculation methods both have the effect of correcting the spectral error.
[0058]
As shown in FIG. 5, first, in step S1, light is received by the first and second sensors according to the present invention. In step S2, each sensor outputs voltages E1 and E2 corresponding to the received light to the calculation means.
[0059]
Thereafter, in step S3, the solar radiation intensity is calculated by the formula (2) or (4), the calculation result is sent to the display means, and the result is displayed (step S4).
[0060]
The calculation method in the step S3 will be described in detail below.
[0061]
6 and 7 are functional block diagrams illustrating first and second methods of calculating solar radiation intensity according to the present invention, respectively.
[0062]
As shown in FIG. 6, the calculation means 70 for performing the first calculation method of the present invention is a first recording unit for recording the value of the coefficient K1 described in the above equation (2), and the value of the coefficient K2. A second recording unit for recording, a third recording unit for recording the coefficient K3, and an arithmetic unit for executing equation (2). The calculation means 70 of the present invention is further connected to display means such as a liquid crystal display device.
[0063]
The calculation means 70 of the present invention connects the first sensor and the second sensor, and receives the voltages (E1, E2) according to the intensity of light when the sensor receives light. The arithmetic unit receives the output voltages E1 and E2, reads out the coefficients from the first to third recording units, and calculates the solar radiation intensity according to the equation (2).
[0064]
G = E1 * K1 + E2 * K2 + K3 (2)
Thereafter, the obtained calculation result signal is transmitted to the display means, and the result is displayed.
[0065]
As shown in FIG. 7, the calculation means 70 that performs the second calculation method of the present invention includes a fourth recording unit that records the value of the coefficient K4 described in the above-described equation (4), and the value of the coefficient K5. , A sixth recording unit that records the value of the coefficient K6, and an arithmetic unit that executes Equation (4). The calculation unit receives the output voltages E1 and E2, reads out the coefficients from the recording unit, and calculates the solar radiation intensity according to the equation (4).
[0066]
G = K4 * E1 + K5 * R + K6 (4) Here, there is a relationship of R = E1 / E2.
[0067]
Thereafter, the obtained calculation result signal is transmitted to the display means, and the result is displayed.
[0068]
A program according to the present invention causes a computer to execute each step of the calculation method according to the present invention and causes each step to function.
[0069]
Examples of the computer-readable recording medium for recording the program of the present invention include a magnetic recording medium (a recording medium capable of magnetically reading data such as a flexible disk, a magnetic card, and a magnetic tape), and an optical recording medium ( CD-RAM, CD-ROM, DVD-RAM, DVD-ROM, DVD-R, MD disk, MO disk or other optically readable recording medium) or memory element (DRAM or other semiconductor memory element) A portable recording medium such as a memory cartridge provided with a ferroelectric memory element such as FRAM) is preferable.
[0070]
The results obtained by such a calculation method are shown in FIG. The horizontal axis of FIG. 8 shows the solar radiation intensity by a thermal solarimeter with no spectral error, and the vertical axis is the solar radiation intensity ratio in the case of the Si sensor alone with respect to the solar radiation intensity of the thermal solar radiation meter, and is given by equation (2). The output ratio by the composite sensor comprised from Si and InGaAs is shown. It can be seen that the spectral error is further improved over a wide range of solar radiation intensity from this output ratio, with the ratio being close to 1.0. Similar results were obtained for equation (4).
[0071]
That is, in both cases of the above formulas (2) and (4), the output information is increased to two, so that more accurate measurement is possible.
[0072]
FIG. 9 shows the result of comparing various performances of the thermal type pyranometer and the pyranometer according to the present invention.
[0073]
A method for evaluating each performance will be described below.
[0074]
The response speed was evaluated by the time (seconds) required to reach 95% of the maximum output value when exposed to a constant light from the light-shielded state. The smaller the time value, the faster the response speed.
[0075]
Zero offset is a measure that is affected by the external temperature, taking into account the effects of the atmospheric temperature and wind speed of the upper layer. Radiation balance caused by the difference between the atmospheric temperature and the specific surface temperature is 200 W / m ² Deviation when there is no. The smaller the zero offset value, the less affected by the external temperature.
[0076]
Aging is a measure of the stability of sensitivity, and was determined by the rate of change in sensitivity per year.
[0077]
The non-linearity, relative to the 500 W / ^{m 2,} refers to the relationship between output responsive the radiation amount of light between the preceding and 100 to 1000 W / ^{m 2,} The smaller the value, linearity, That is, the relationship between the response output and the amount of light emitted is linear.
[0078]
The angle characteristic is obtained from a measurement error when a radiant flux of 1000 W / m ² is received from all directions. The smaller this value is, the more the solar radiation intensity that does not depend on the incident angle of light can be measured.
[0079]
The tilt characteristic refers to the rate of change when tilted from 0 degrees (horizontal) to 90 degrees (vertical) during 1000 W / ² irradiation. As this value is smaller, the solar radiation intensity is less dependent on the inclination and can be measured.
[0080]
As is clear from the results of FIG. 9, from the comparison of the performance of the conventional thermal pyranometer and the two-element pyranometer according to the present invention, in the pyranometer according to the present invention, the response speed, zero offset, secular change of sensitivity, inclination It was found that the characteristics were improved.
[0081]
Although the above description has explained a pyranometer using two quantum sensors, the pyranometer using two or more quantum sensors also has two quantum types in order to further reduce spectral errors. It is possible to change the pyranometer with another filter attached to the sensor from the content disclosed in the present invention.
[0082]
【The invention's effect】
According to the present invention, a low price, high response speed, and good zero offset, secular change, non-linearity, and tilt characteristics can be obtained by using a plurality of the pyranometers using quantum sensors.
[0083]
In addition, it is very important to know the solar radiation intensity in all directions and inclination angles, but these values are currently estimated by calculation etc. The pyranometer according to the invention is useful.
[Brief description of the drawings]
FIG. 1 is a diagram showing the spectral solar radiation intensity of solar radiation to be measured, and shows that the solar radiation spectrum changes depending on the solar altitude. In order from the top in FIG. 1, the solar radiation spectrum at the time of fine weather at solar altitudes of 90 degrees, 41.8 degrees, and 30 degrees is shown.
FIG. 2 shows relative spectral sensitivity curves of a Si sensor and an InGaAs sensor, which are quantum sensors for detecting solar radiation.
FIG. 3 is a schematic cross-sectional view of a first type of pyranometer according to the present invention.
FIG. 4 is a schematic cross-sectional view of a second type of pyranometer according to the present invention.
FIG. 5 is a flowchart illustrating a method of calculating solar radiation intensity according to the present invention.
FIG. 6 is a functional block diagram illustrating a first calculation method according to the present invention.
FIG. 7 is a functional block diagram illustrating a second calculation method according to the present invention.
FIG. 8 is a diagram showing that the spectral error is improved by the pyranometer according to the present invention.
FIG. 9 is a diagram showing a result of comparing the performance of a conventional thermal pyranometer and a pyranometer using two quantum sensors according to the present invention.
[Explanation of symbols]
10, 100 Pyrometer 20 Diffuser 30 Si sensor 40 Si sensor 50 Optical filter 60 Desiccant container 70 Calculation means 80 Level 90 Output connector 120 Si sensor 130 InGaAs sensor

Claims (8)

In a pyranometer using a quantum sensor ,
The first quantum sensor,
A second quantum sensor with an optical filter;
A calculation means for calculating a solar radiation intensity in response to a first output voltage from the first quantum sensor and a second output voltage from the second quantum sensor ;
A first recording unit that records the first coefficient K1, a second recording unit that records the second coefficient K2, and a third recording unit that records the third coefficient K3; With
[Formula 1]

(Here, G indicates solar radiation intensity, and E1 and E2 indicate the first output voltage and the second output voltage, respectively.)
A solar radiation meter that calculates solar radiation intensity from the relationship. In a pyranometer using a quantum sensor ,
The first quantum sensor,
A second quantum sensor with an optical filter;
A calculation means for calculating a solar radiation intensity in response to a first output voltage from the first quantum sensor and a second output voltage from the second quantum sensor ;
The calculation means includes a fourth recording unit for recording the fourth coefficient K4, a fifth recording unit for recording the fifth coefficient K5, and a sixth recording unit for recording the sixth coefficient K6. Prepared,
[Formula 2]

(Here, G indicates solar radiation intensity, and E1 and E2 are referred to as the first output voltage and the second output voltage, respectively, and R = E1 / E2.)
A solar radiation meter that calculates solar radiation intensity from the relationship. In a pyranometer using a quantum sensor ,
The first quantum sensor,
A second quantum sensor having a different photosensitive wavelength band from the first quantum sensor;
A calculation means for calculating a solar radiation intensity in response to a first output voltage from the first quantum sensor and a second output voltage from the second quantum sensor ;
A first recording unit that records the first coefficient K1, a second recording unit that records the second coefficient K2, and a third recording unit that records the third coefficient K3; With
[Formula 3]

(Here, G indicates solar radiation intensity, and E1 and E2 indicate the first output voltage and the second output voltage, respectively.)
A solar radiation meter that calculates solar radiation intensity from the relationship. In a pyranometer using a quantum sensor ,
The first quantum sensor,
A second quantum sensor having a different photosensitive wavelength band from the first quantum sensor;
A calculation means for calculating a solar radiation intensity in response to a first output voltage from the first quantum sensor and a second output voltage from the second quantum sensor;
The calculation means includes a fourth recording unit for recording the fourth coefficient K4, a fifth recording unit for recording the fifth coefficient K5, and a sixth recording unit for recording the sixth coefficient K6. Prepared,
[Formula 4]

(Here, G indicates solar radiation intensity, and E1 and E2 are referred to as the first output voltage and the second output voltage, respectively, and R = E1 / E2.)
A solar radiation meter that calculates solar radiation intensity from the relationship.   The solar radiation meter according to claim 1 or 2, wherein the first and second quantum sensors are Si sensors.   The solar radiation meter according to claim 1 or 2, wherein the optical filter is a cut-off filter.   The solar radiation meter according to claim 3 or 4, wherein the first quantum sensor is an Si sensor and the second quantum sensor is an InGaAs sensor.   The pyranometer according to any one of claims 1 to 7, further comprising display means for displaying a calculation result by the calculating means.

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