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    • 专利摘要:
    The present invention relates to a real-time measurement system for atmospheric attenuation of electromagnetic radiation from a source (40), comprising at least two telescopic optical radiation capture devices (10, 20) located at different distances from said source, a real-time detection and measurement device optically connected to each of the telescopic optical devices to provide simultaneous monochrome, spectral and total radiation measurements in the solar spectral range. The invention also relates to a measurement method that provides the measurement of attenuation over the entire spectral range for the best evaluation of the performance of energy systems and to achieve a differentiated measure of the meteorological phenomena that cause such attenuation, thus providing relevant information. for the weather forecast in this specific field. (Machine-translation by Google Translate, not legally binding)
    公开号:ES2738912A1
    申请号:ES201830758
    申请日:2018-07-25
    公开日:2020-01-27
    发明作者:Peruchena Carlos Fernández；García Ana Bernardos；González Marcelino Sánchez；Vila Carlos Heras；Ariz Iñigo Salina；Esteban Rafael Alonso
    申请人:Fundacion Cener Ciemat；
    IPC主号:
    专利说明:

    [0001] REAL-TIME MEASUREMENT SYSTEM OF THE ATMOSPHERIC ATTENTION OF A
    [0002]
    [0003] OBJECT OF THE INVENTION
    [0004] The present invention, a real-time measurement system of the atmospheric attenuation of electromagnetic radiation of solar rays at ground level from at least one source, refers to a system of measurement of monochromatic attenuation for each wavelength of the spectrum, of the spectral attenuation in the spectral range of measurement, and of the total attenuation. The invention also relates to a measurement method.
    [0005] The invention provides a measure of the attenuation over the entire spectral range for the best evaluation of the performance of energy systems and to achieve a differentiated measure of the meteorological phenomena that cause such attenuation, thus providing relevant information for the meteorological prediction in this specific field.
    [0006] The invention is part of the energy generation sector by capturing solar energy.
    [0007]
    [0008] DESCRIPTION OF THE STATE OF THE TECHNIQUE
    [0009] The performance of the central receiver solar plants is influenced by the optical performance of the set of collector elements, the atmospheric attenuation of the rays reflected by said collectors to the receiving element, one of the components that have the greatest influence on the performance of the power station on days of low visibility, where the content of aerosols and gases present in the atmosphere at ground level is higher.
    [0010] The atmospheric attenuation of the solar rays reflected by the collector elements on their way to the receiving element is caused by the phenomena of dispersion (or diffusion) and absorption of electromagnetic waves when they cross the atmosphere at ground level. Both the dispersion, change of direction of the wave, and the phenomenon of energy absorption, is caused by the interaction with the particles and aerosols suspended in the atmosphere, as well as gases dissolved in it. This attenuation is a function of the type and number of molecules present in the path of the sun's rays.
    [0011] The main attenuating element in the trajectory of these rays are aerosols, small particles (solid or liquid) in suspension. They are difficult to model and predict, and they come from a wide variety of sources (such as suspended dust, sandstorms, urban and industrial pollution, sea mists, etc.). The dominant attenuating phenomenon in the case of aerosols is dispersion, presenting a strong spectral dependence depending on their size distribution ( Shaw, GE, Reagan, JA, & Herman, BM ( 1973). Investigations of atmospheric extinction using direct solar radiation measurements made with a multiple wavelength radiometer, Journal of Applied Meteorology, 12 ( 2), 374-380. ). On the other hand, the atmospheric gases present in the trajectory of said rays produce both dispersion and absorption (water vapor, ozone, NO2 and other gases), being in this case the attenuating phenomenon of greater weight the absorption. There are also spectral bands associated with the different atmospheric gases where absorption is more significant.
    [0012] It should be noted, therefore, that the mass of atmospheric air, including its suspended particles, present between the path of the sun's rays reflected by the collector elements on their way to the receiving element constitutes a spectral filter that can vary along the day, depending on the variation of aerosols, chemical composition of the air and even meteorological parameters ( Rahoma, UA, & Hassan, AH ( 2012). Determination of atmospheric turbidity and its correlation with climatologically parameters. Am. J. Environ. Sci, 8, 597-604 ; and Wen, CC, & Yeh, HH ( 2010). Comparative influences of airborne pollutants and meteorological parameters on atmospheric visibility and turbidity. Atmospheric Research, 96 ( 4), 496-509 ). Likewise, the Earth's atmosphere also constitutes a variable spectral filter of the solar radiation from the sun, which depends both on its composition (aerosols and water vapor mainly) and on the length traveled through it (which depends both on the time of the year as of the time of day), which causes the spectrum of solar radiation that reaches the ground to vary throughout the year, and even throughout the day ( Iqbal, M. ( 2012). An introduction to solar radiation. Elsevier ).
    [0013] Therefore, a spectral analysis of the phenomenon of solar radiation attenuation at ground level is necessary for its proper characterization and modeling according to atmospheric components (including aerosols) at ground level. That is, a simultaneous measurement of the spectral atmospheric attenuation of the reflected rays as well as other meteorological variables will allow us to model said attenuation based on common variables in meteorology. Likewise, said modeling allows estimating the attenuation for different locations based on the historical of said meteorological values and making a better selection of the location of solar power plants.
    [0014] It is important to highlight that all the phenomena that cause atmospheric attenuation produce differentiated variations of solar radiation throughout their range. spectral, varying the form in a specific and singular way, which ultimately affects the variation of its integrated intensity. Thus, for example, water vapor has specific absorption bands in the Infrared region (940, 1100, 1380 and 1870 nm, among others), while particle dispersion has a greater incidence in the ultraviolet and visible area of the spectrum. Figure 1 shows the spectrum of extraterrestrial solar radiation (upper curve, continuous line) together with two spectra of normal direct radiation at ground level, both at low (intermediate curve, continuous line) and at high (lower curve, dotted line ) atmospheric water vapor concentration. Figure 1 shows a graph with the spectral transmittance of water vapor.
    [0015] Therefore, the measurement of the differentiated atmospheric attenuation at each wavelength makes it possible to distinguish the different physical phenomena that cause it, as well as quantify each of them, which ultimately has a very important incidence on the one hand in the measurement precise of the total atmospheric attenuation, but also its prediction from the available information of the different atmospheric and meteorological phenomena.
    [0016] At present there are no known systems for the spectral measurement of monochromatic atmospheric attenuation at the terrestrial level, which limits the final precision attainable in the measurement and / or estimation of total atmospheric attenuation, as well as its quantification from other meteorological variables .
    [0017] In the state of the art there are experimental proposals for measuring total attenuation, that is, regardless of the frequency within the spectrum. One of these proposals is based on the use of a heliostat, collector used in central technology plants, and several pyrometers aligned with the objective of measuring direct radiation from the sun and reflected by the heliostat at different positions ( Goebel O. Luque F., Alobaidli Salbidoigeta I. 2011. Beam attenuation test for central power plants in high density aaerosols atmosphere. Setup methodology. Solarpaces Granada Spain; and Tahboub Z. Al Alobaidli A. Luque F, Salbidoigeta I., Farges O., Hassar X ., Oumbe A., Geuder N., Goebel O., 2012. Solar beam attenuation experiments in Abu Dhabi, Solar Marrakech, Morocco)
    [0018] By means of this system based on the difference in the radiation measured in the different pyrometers, the measurement of the total terrestrial solar attenuation is differed, but not spectral. In addition, this experience has shown to have great uncertainties due mainly to the accuracy of the pyrometers as well as uncertainty in the geometry of the heliostat and in the ray tracing used.
    [0019] There are also other proposals based on the use of digital cameras ( Ballestrin J., Monterreal R., Carra M. Fernández-Reche J., Barbero J., March A., 2016. Measurement on solar extinction in tower plants with digital cameras. AIP Conference Proceedings 1734, 13002 ), specifically in the simultaneous taking of photographs with digital cameras of a screen at different distances. Similarly, said measurement is not spectral, and also does not have the selective radiation collection systems proposed in the present invention which causes the accuracy of said system to be limited. Specifically, this article quantifies and limits the measuring capacity of the equipment to an area where only approximately 73% of the extinction occurs.
    [0020] Therefore, the following problems are identified in the prior art solutions:
    [0021] - At distances greater than approximately 800 meters it is possible that the captured light does not come exclusively from the useful source, source whose light is to be measured, therefore the use of a telescopic system is proposed
    [0022] - There is chromatic aberration in the measurements of those systems that use lenses, and therefore it cannot be assured that all wavelengths form an image in the same image plane,
    [0023] - The measure does not take into account the difference between the light reflected by the useful source and the diffuse light that is reflected by the atmosphere between said source and the measurement system,
    [0024] - The measurement does not include the entire spectral range of the sun, preferably between 300 nm and 1650 nm, that is, the visible range and the near infrared range, so that significant errors occur when having to assume the spectral form of atmospheric attenuation of the infrared range (not measured by known systems) from atmospheric attenuation in the visible range.
    [0025] - There are errors in the measurement derived from the fact that the response of the measurement sensors are dependent on the wavelength, and therefore give different weight to the different spectral components of the light, and
    [0026] - None of the systems of the prior art carries out a study and diagnosis of the cause of atmospheric attenuation.
    [0027] - None of the systems of the state of the art make measurements of monochromatic atmospheric attenuation, spectral attenuation and total attenuation in a differentiated manner.
    [0028] In view of the foregoing, the present invention proposes a system and method of measuring atmospheric spectral attenuation that allow obtaining greater precision in the measurement of said attenuation.
    [0029]
    [0030] DESCRIPTION OF THE INVENTION
    [0031] The present invention, a real-time measurement system for atmospheric attenuation of an electromagnetic radiation from at least one source, has as its first object a system according to claim 1. Said system serves to characterize in real time the causes of atmospheric attenuation of Electromagnetic radiation in the solar spectrum by spectral measurement of solar radiation at the ground level. Specifically, it refers to a measurement system of:
    [0032] - the monochromatic attenuation for each wavelength of the spectrum, understanding as such the attenuation at a wavelength of the spectrum with the spectral width provided by the measuring equipment,
    [0033] - the spectral attenuation in the spectral measurement range, understanding as such the set of monochromatic attenuations at all wavelengths along the spectral measurement range, and
    [0034] - the total attenuation, understanding as such the attenuation that is calculated by integrating the spectral attenuation in the spectral measurement range weighted with the solar spectrum.
    [0035] The system is based on the separate arrangement of at least two light-sensing devices, associated with measuring devices, and aligned with a light source or useful source, to infer the attenuation of solar energy in the distance between said devices. light collectors by means of real-time difference of the spectral energy that affects them.
    [0036] Specifically, the system object of the invention for the real-time measurement of atmospheric attenuation of an electromagnetic radiation from at least one source, preferably a hemispherical reflectance screen to reflect the incident solar radiation, and which has at least the following elements :
    [0037] - At least two telescopic optical devices for capturing a beam of radiation from only said useful source and located at different distances from said source, which ensure that only radiation from the light source is captured
    [0038] - At least one real-time detection and measurement device, preferably an optically connected photodiode array spectrophotometer, preferably by optical fiber, to each of the telescopic optical devices to provide simultaneous monochromatic spectral measurements of the radiation at least in the solar spectral range between 300 nm and 1650 nm, including the ultraviolet, visible and infrared ranges.
    [0039] - At least one processor to perform measurements from the signals detected by the detection and measurement devices and associated with these devices,
    [0040] - At least one general processor for communication between the detection and measurement devices based on the data of each processor of each detection and measurement device to, from the recorded information and comparing said information in real time, calculate the values of monochromatic attenuation, spectral attenuation and global attenuation
    [0041] - At least one alignment system of the telescopic device with the source, preferably by means of a digital camera (preferably CCD) visualization of the captured image.
    [0042] When the beam is captured by the telescopic optical device it is divided into as many beams as detection and measurement devices associated with each optical device exist, so that the divided beams are guided and focused to said measuring devices covering each measuring device a different region of the spectral range to be measured. The connection between the optical device and the measuring device (s) is preferably made by means of optical fiber. This division can be done either by means of optical beam splitters or by multifibers, with multifibers being understood as a cable of two or more optical fibers in which at the light entry end all the fibers are together so that each fiber collects a part of the beam of light and at the other end each fiber is separated and allows to take its part of guided light to different points. Also, the measuring devices can be array spectrometers of photodiodes or monochromator equipment.
    [0043] A second object of the invention is a method for real-time measurement of the atmospheric attenuation of an electromagnetic radiation from a source with a system as described above. In particular, the measurement procedure comprises the following steps:
    [0044] a) Align at least two telescopic optical devices, located at different distances from the source, to the source of electromagnetic radiation,
    [0045] b) Capture a beam of electromagnetic radiation reflected in the source by means of each of the telescopic optical devices,
    [0046] c) Detect and perform monochromatic measurements in the different spectral regions covered by the detection devices and measure the captured radiation, and
    [0047] d) Calculate in real time monochromatic atmospheric attenuation, spectral attenuation and total attenuation by comparing monochromatic spectral measurements.
    [0048]
    [0049] The method contemplates that, prior to the alignment towards the useful source of electromagnetic radiation of the devices, these are aligned with a black target or absorbing screen to measure the light background and subsequently consider the discount of the light background to the extent of the attenuation, so that all the light that is scattered in the path that goes from the screen to the optical device and that does not come from the beam that travels from the screen to said device (which is the one that you want to measure) does not influence the final measure
    [0050] On the other hand, the procedure allows spectroscopic techniques and spectral analysis to be applied after the atmospheric attenuation calculation, to identify and discern the phenomena that cause the previously calculated atmospheric attenuation.
    [0051] Also, to perform the calibration of the measurement system, prior to the alignment of the telescopic optical devices it is convenient to perform a calibration process of the detection and measurement devices by placing the telescopic optical devices at the same distance from the source of electromagnetic radiation.
    [0052] From the system and method object of the present invention it is possible to increase the precision of the attenuation measurements with respect to the systems of the prior art.
    [0053] The invention allows the light coming from the useful source to be captured, with an acceptance angle (maximum angle at which the incident light beam is captured and measured by the measuring device) of the order of 1 to 3 mrad to ensure that at a distance of 1 km only light from this system source is captured. This is because the telescopic optical device comprises an optical system that targets a large focal length and a very small input diaphragm, so that the acceptance angle of the optical system, defined as the ratio between the input diaphragm and the focal length of the objective is very small, of the order of 1 mrad. In this way, a telescopic optical device arranged at a distance of 1 km from the useful source only captures the light reflected by an object of a size of 1 meter [1mradx1km = 1m]. If the acceptance angle is not limited, the system would capture light that comes from outside the useful source of the system, which can lead to measurement errors. In the case of state-of-the-art systems that use cameras as sensors, they limit the angle of acceptance with the camera pixels they use to calculate the light power. This results in problems if there is chromatic aberration, since each wavelength can go to different pixels of the digital camera.
    [0054] The system object of the invention is preferably based on reflectors as optical imaging elements to ensure that there is no chromatic aberration and therefore ensure that all wavelengths form an image in the same image plane. When using reflectors, or mirrors, as optical elements, the problem of chromatic aberration does not occur. Chromatic aberration can lead to errors in the case of the use of digital cameras as sensors, since each wavelength can form images in different pixels of the camera, so there will be pixels in which light from the source is detected of useful or target light and light coming from outside the useful light source.
    [0055] The invention contemplates the possibility of preferably using two targets as a light source, a highly reflective or white target used as a useful light source for measuring atmospheric attenuation and a null or black reflection target, as mentioned above, used as a background measurement of light in the atmospheric attenuation measurement system. In state-of-the-art digital camera-based measurement systems, only one useful light source is used, which is a target that reflects from sunlight. This may have a problem because the measurement system not only reaches the light coming from the target, but also part of the diffused light that reflects the atmosphere that is in the direct path from the camera to the target, and that forms a light background that is variable with the conditions of the atmosphere and that adds to the light coming from the target. In the measurement system object of the present invention the same thing happens, that is, the light of the target and part of the diffused light that is in the direct path from the target to the measurement system is detected, and for this reason, To eliminate the background of diffused light, the system proposes to use a dark target that does not reflect any sunlight. Thus, when the measurement system is directed to the dark target, only diffused light is measured, which is the background that is discounted in the measurement. In the preferable embodiment of the system, a white target would be arranged as a source and next to it, preferably below, a black target. In this way, to perform the measurement, the telescopic optical device should first be oriented to the black target to measure the diffuse light background, and then the telescopic optical device should be oriented to the white target to measure the useful light source discounting the measure of the black target.
    [0056] As mentioned, the realization of the measurement of the attenuation over the entire spectral range of the sun, that is, in the visible and near infrared range, avoids significant errors that do occur in the state of the art since there is no need to assume the spectral form of atmospheric infrared attenuation from atmospheric attenuation in the visible. The fact of measuring the power exclusively in the visible spectrum, due to the use of exclusively silicon sensors or digital cameras whose sensor elements are of Silicon, limit the detection of a spectral range of up to 1050nm. However, an important part of solar radiation is in the infrared spectrum, that is, up to approximately 1600 nm, and atmospheric attenuation does not have the same weight in the visible as in the infrared. By measuring the entire solar spectrum, significant errors are avoided to the extent that they occur in prior art systems. Thus, the present invention proposes the use of silicon sensors for measuring the spectrum from 300 nm to 1050 nm and indium gallium arsenide (InGaAs) sensors for measuring the spectrum from 900 nm to 2600 nm to cover the entire solar spectrum to Get a more accurate measurement. However, for the preferred embodiment of this invention, the spectrum measurement is proposed up to 1650 nm for technical and economic reasons.
    [0057] Likewise, the system object of the present invention makes a measurement of the optical spectrum of the detected light, unlike known systems that perform an integrated measurement of the power of the measured light spectrum, thus avoiding measurement errors. These errors are due to the fact that Silicon and InGaAs sensors have a response strongly dependent on wavelength. For example, in silicon the response in 600nm is half that in 800nm, so if an optical spectrum measurement is not made, this dependence cannot be discounted. All state-of-the-art systems make a measurement with a sensor or a digital camera, and therefore it is a measure that integrates the entire spectrum of the measured light, either from an LED or lamp or from the sun, in which the source spectrum is multiplied with the detector response. Therefore, the response of the detector cannot be discounted. If the atmospheric attenuation varies in the different wavelengths, as it really happens, in the systems of the state of the art an error can be made in the measurement of the atmospheric attenuation since a variation for example in 800nm will have a weight in the measurement which will be double that a variation in 600nm. In order to avoid this, it is necessary to have a spectrum measurement, which is what the system of the present invention does, so that it can discount the response of Silicon and InGaAs for each wavelength, obtaining a measure of atmospheric attenuation more precise.
    [0058] Due to the above, that is, the fact that a measurement of the optical spectrum of the measured light is made, it is possible to carry out a study and diagnosis of the cause of atmospheric attenuation by having the measurement of the spectral attenuation of the atmosphere since it is the only way to identify the causes of attenuation. In addition, for this reason, the system object of the invention is the only one that can establish correlations between atmospheric conditions that can be measured with other measuring devices such as humidity, particles, pollution, etc ... and atmospheric attenuation.
    [0059]
    [0060] DESCRIPTION OF THE FIGURES
    [0061] The following figures are attached to the present description showing a preferred embodiment of the invention for illustrative and non-limiting purposes:
    [0062] Figure 1 shows a spectrum of extraterrestrial solar radiation (upper curve) next to spectra at ground level for different atmospheric water vapor concentrations. It also shows, in the upper right, the transmittance of water vapor.
    [0063] Figure 2 shows a preferred embodiment of the solar radiation attenuation measurement system object of the invention.
    [0064] Figure 3 shows a second preferred embodiment of the solar radiation attenuation measurement system object of the invention in which an absorber screen is included.
    [0065] Figure 4 shows a preferred scheme of a telescopic optical device for capturing a beam of light.
    [0066] Figure 5 shows a preferred scheme of the detection and measurement device provided with dividers.
    [0067] Figure 6 shows a preferred scheme of the detection and measurement device provided with multifiber.
    [0068] Figure 7 shows the spectroscopic measurements performed by the reference device and the measuring device for the calculation of the spectral attenuation (Intensity in arbitrary units, u.a., with respect to the wavelength).
    [0069] Figure 8 shows the variation between the two previous measurements that results in the existing spectral attenuation (Variation in% with respect to wavelength).
    [0070]
    [0071] PREFERRED FORM OF EMBODIMENT
    [0072] As already mentioned, the present invention relates to a system and method of measuring the atmospheric attenuation of electromagnetic radiation, so differentiated and precise in each wavelength, that is, in a spectral way, allowing the characterization of the phenomena causing it, in the space between different points.
    [0073] The proposed system (Figures 2 and 3) is preferably composed of a useful source of emission 40, of electromagnetic radiation and at least two devices 10, 20 for capturing the radiation emitted by said source located apart from each other and at different distances from the cited source 40. The useful source of electromagnetic radiation emission can be both artificial and natural (the sun as both direct and reflected source). The optical devices 10, 20 for capturing electromagnetic radiation must be telescopic and must ensure a capture of electromagnetic radiation only from said source 40, which is achieved by adapting the acceptance angle (maximum angle at which the light beam incident is trapped) to the geometric considerations of the system (font size, and distance between the source 40 and the detecting devices 10, 20). Preferably the useful source will be a screen 40 reflecting the direct sunlight beam from the sun 60 or a beam of light previously reflected by at least one heliostat 50. For example, the acceptance angle ( a ) is 1 mrad, being the acceptance angle (a) as defined above, the greater angle with which the rays from an object or source impinge on the detection system and which are detected by said detection system.
    [0074] The telescopic optical reference and measuring devices 20, each arranged at a distance D different from the source 40, preferably have a telescopic objective 11, followed by a field diaphragm 12 determining the focal length 1 of the device 10, 20 , followed by an eyepiece 13 to amplify the signal (figure 4). After the eyepiece 13, a beam splitter 15 (figure 5) or multifibers 25 (figure 6) can be used to divide and direct the captured signal to each detection and measurement device 23, 24.
    [0075] Note the use of reflecting telescopes (which makes use of mirrors instead of lenses to focus light and form images), which prevent the acceptance angle (a) from changing with the wavelength. The telescopic optical devices 10, 20 could employ a telescope of the refractor type.
    [0076] The electromagnetic radiation from the source 40 captured by the telescopic optical devices 10, 20 will be conducted to at least one real-time detection and measurement device 23, 24, associated with each telescopic optical device 10, 20 (Figures 2 to 6) , which will provide simultaneous measurements of its spectrum in real time and in a spectral range that is sufficiently wide for the application considered, preferably between 300 nm and 1650 nm (see figure 7). The comparison of the curves Spectral obtained from the measurements of each detection and measurement device 23, 24 will provide as a result the relative spectral atmospheric attenuation of the electromagnetic radiation considered (see Figure 8). Performing a previous calibration between both optical devices 10, 20 allows obtaining the absolute measurement of spectral attenuation.
    [0077] According to a preferred embodiment (Figure 2), and as mentioned above, as a source of electromagnetic radiation emission, sunlight 60 itself is proposed reflected hemispherically by a white light diffuser screen 40 located at the maximum height at which the attenuation measurement is to be carried out next to a telescopic optical light device 10 close to the source and that acts as a reference measure of the light signal located at ground level and to a telescopic optical device 20 located farther from the source and that acts as a measure of the light signal attenuated by the atmosphere also located at ground level. Additionally, the energy reflected by said screen 40 can be increased by affecting solar energy reflected by one or more heliostats 50. According to said preferred embodiment, the screen 40 is located at the height of the receiver of a solar plant of central receiver concentration (or tower 30), and the telescopic optical devices 10, 20 associated with their detection and measurement devices 23, 24 of the dimmed light signal are located at two distances from the central receiver within the solar field, for example 300 meters (reference device 10) and at 1600 meters (measuring device 20) of the source 40. These distances may vary depending on the size of the solar field or other conditions.
    [0078] The use of the sun 60 as a light source simplifies the optical system and ensures a range, and spectral distribution, suitable for modeling the attenuation phenomenon at the site itself (or any other location), both for prediction purposes, such as of resource estimation in the absence of recorded data.
    [0079] It should be noted that the screen 40, preferably circular or rectangular, although other geometric shapes are possible, must have a hemispherical reflectance to avoid the presence of privileged directions in the reflection and thus have a spatially uniform source. Also, this screen 40 must be of a sufficiently large size to ensure that the telescopic optical device 20 of the dimmed light signal, the farthest, only captures light from the screen 40 and thus avoids variable background signals that they would lead to uncertainties to the extent. The screen size ( T ) must be related to the acceptance angle ( a ) or input aperture of the optical measuring system 20 of the light signal and the distance ( D ) between said system 20 and the screen 40, of according to the following equation: T> D * tan (a)
    [0080] Specifically, for a distance of 1600 m and an opening of 1 mrad, the size of the fountain must be greater than a circle with a diameter of approximately 1.6 meters. The value of the input aperture of the optical measurement system of the light signal is determined by the focal length of the target 11 and the field diaphragm 12. The preferred embodiment proposes that, once the light signal is captured by the reference optical device 10 and by the optical measuring device 20 of the attenuated light signal, they are transmitted by optical means, preferably optical fiber 21, 22 to a photodiode array spectrometer device 23, 24 for measuring their spectrum in real time simultaneously by both telescopic devices.10, 20
    [0081] To cover a sufficient spectral range in the case of sunlight, said preferred embodiment proposes the use as detection and measurement devices 23, 24 of two photodiode array spectrometers: one, preferably an array of silicon detectors 23, in the range of 300 nm to 1050 nm, and the other, preferably an array of InGaAs 24 detectors, in the range of 900 nm to 1650 nm. To enable the real-time measurement of both spectral ranges, the beam captured by each telescopic optical device 10, 20 must be divided, preferably with a beam splitter 15, although it is also possible by multifibers 25, and focused on the optical means 23 , 24, preferably the optical fiber 21, 22, 25, by focusing lenses 16, 18.
    [0082] In addition, a system that allows the alignment of the telescopic systems with the screen is necessary, said system including both optical and mechanical components. This alignment requires a division 14 of the beam, prior to that described, in order to be able to visualize the captured image in a digital camera 17 (preferably CCD). In a preferred embodiment, it is proposed that the telescopic systems 10, 20 be aligned to the screen manually.
    [0083] The described schemes, both the telescopic optical device 10, 20 and the detection and measurement device 23, 24, together form the reference and measurement systems of the attenuated light signal. Each of said devices provides a measure of the spectral curve of sunlight reflected by the screen in the range of 300 nm to 1650 nm, with a resolution in spectral width of for example 0.5 nm.
    [0084] As mentioned, a possible measuring device 23, 24 is constituted by photodiode array spectrometers in which the sensors are grouped in a matrix, or monochromator equipment, which, based on the phenomenon of refraction or diffraction, Spatially separate the different wavelengths present in the signal. In this way, the system will provide measurements of the light signal to each wavelength of the specified spectral range, that is, spectral curves of the intensity of the light signal (figure 7).
    [0085] By direct comparison of these curves, monochromatic atmospheric attenuation is obtained (Figure 8) for each wavelength between 300 nm and 1650 nm with the spectral resolution of 0.5 nm of the electromagnetic radiation considered from the screen to the measurement system . The set of all monochromatic attenuations provides the values of the curve of the spectral attenuation of the electromagnetic radiation considered between 300 nm and 1650 nm. The values of the curve of said spectral attenuation, weighted with the spectrum of electromagnetic radiation, provide the value of the overall attenuation in the range of 300 nm to 1650 nm.
    [0086] To obtain an absolute measurement, prior calibration between the measurements obtained by the reference and measurement systems must be ensured, and the difference in travel between the reference systems and the screen must be considered.
    [0087] It should be noted that the signals, both reference and measurement, may be contaminated by the light scattered by the atmospheric components present between the screen and the telescopic systems (for example, aerosols), which we will define as backlight.
    [0088] To characterize said backlight, in another preferred embodiment (Figure 3), the system object of the invention contemplates that the telescopic optical devices can be aligned towards an absorber screen 45, that is, that it has a very low reflectivity (as close as possible). at 0%), and in particular, much lower than that of the hemispherical reflectance screen 40 described above (with a reflectivity as close as possible to 100%) and used to provide reflected radiation towards telescopic optical devices. Thus, the signal measured by the telescopic systems aligned towards the absorber screen 45 can be taken into account to quantify and model the attenuation phenomenon.
    [0089] The method of operation of the previous systems has the following stages:
    [0090] - Alignment of at least two telescopic optical devices 10, 20, located at different distances from the source 40, towards the source of electromagnetic radiation 40,
    [0091] - Collection of a beam of electromagnetic radiation reflected in the source 40 by means of each of the telescopic optical devices 10, 20, - Monochromatic detection and measurements in the different spectral regions covered by the detection and measurement devices 23, 24 of the captured radiation (Figure 7), and
    [0092] - Real-time calculation of atmospheric attenuation by comparing monochromatic spectral measurements (figure 8).
    [0093] The method preferably comprises a previous stage, prior to the alignment towards the source of electromagnetic radiation of the devices 10, 20, in which the devices 10, 20 are aligned with an absorbing screen (figure 3) to measure the light background and then consider the discount of the light background in the measure.
    [0094] Likewise, after the calculation of the atmospheric attenuation, the procedure comprises a stage of application of spectroscopic techniques and spectral analysis to identify and discern the phenomena causing the previously calculated atmospheric attenuation. Preferably also, before the alignment of the telescopic optical devices 10, 20 a calibration process of the detection and measurement devices 23, 24 is carried out by placing the telescopic optical devices 10, 20 at the same distance from the source 40 of electromagnetic radiation .
    权利要求:
    Claims (17)
    [1]
    1. Real-time measurement system of the atmospheric attenuation of an electromagnetic radiation from at least one source, characterized in that it comprises:
    - At least two telescopic optical devices for capturing a beam of radiation from only said source and which are located at different distances from said source,
    - At least one real-time detection and measurement device optically connected to each of the telescopic optical devices to provide simultaneous monochromatic, spectral and total radiation measurements in the solar spectral range.
    - At least one processor to perform measurements from the signals detected by the detection devices,
    - At least one general processor for real-time comparison and communication between detection and measurement devices, and
    - At least one optical alignment system of the telescopic device with the source.
    [2]
    2. System according to claim 1, characterized in that the beam captured by the telescopic optical device is divided into as many beams as detection and measurement devices are connected to the optical device, said beams being guided and focused to said detection devices, each device comprising a different region of the spectral range to be measured.
    [3]
    3. System according to claim 2, characterized in that the beam is divided by optical beam splitters.
    [4]
    4. System according to claim 2, characterized in that the beam is divided by multifibers.
    [5]
    5. System according to claim 1, characterized in that the detection and measurement devices are photodiode array spectrometers.
    [6]
    6. System according to claim 1, characterized in that the detection and measurement devices are monochromator equipment.
    [7]
    7. System, according to any of the preceding claims, characterized in that the alignment system comprises a digital camera to be able to visualize the captured image of the source.
    [8]
    System according to any of the preceding claims, characterized in that it comprises a reflective screen as a source that reflects sunlight towards the telescopic optical capture devices.
    [9]
    9. System, according to claim 8, characterized in that it comprises an absorbent screen, located close to the reflective screen, to discount the backlight in the measurement.
    [10]
    10. System according to claim 1, characterized in that the telescopic optical device comprises an acceptance angle equal to or less than the angle subtended by the source on said device.
    [11]
    11. System according to any of the preceding claims, characterized in that the telescopic optical device is of the reflector telescope type.
    [12]
    12. System according to any of the preceding claims, characterized in that the telescopic optical device is of the refracting telescope type.
    [13]
    13. System according to claim 8, characterized in that the reflective screen reflects the sunlight reflected by at least one heliostat towards the telescopic optical capture devices.
    [14]
    14. Method for measuring in real time the atmospheric attenuation of an electromagnetic radiation from a source by means of a measurement system according to the preceding claims, characterized in that it comprises the following steps:
    a) Align at least two telescopic optical devices, located at different distances from the source, to the source of electromagnetic radiation, b) Capture a beam of electromagnetic radiation through each of the telescopic optical devices,
    c) Detect and perform monochromatic measurements in the different spectral regions covered by the detection and measurement devices of the captured radiation, and d) Calculate in real time the atmospheric attenuation by comparing the monochromatic spectral measurements.
    [15]
    15. Method according to claim 14, characterized in that prior to the alignment towards the source of electromagnetic radiation of the devices, these are aligned with an absorbing screen to measure the background of light and subsequently consider the discount of the background of light in the measure.
    [16]
    16. Measurement method according to claim 14, characterized in that after the calculation of atmospheric attenuation it comprises a stage of application of spectroscopic techniques and spectral analysis to identify and discern the phenomena causing the previously calculated atmospheric attenuation.
    [17]
    17. Method according to claim 14, characterized in that prior to the alignment of the telescopic optical devices a calibration process of the detection and measurement devices by placing telescopic optical devices at the same distance from the source of electromagnetic radiation.
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    同族专利:
    公开号 | 公开日
    CL2021000110A1|2021-08-06|
    US20210223101A1|2021-07-22|
    CN112437871A|2021-03-02|
    WO2020021146A1|2020-01-30|
    ES2738912B2|2020-10-30|
    EP3799620A1|2021-04-07|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    US20140247442A1|2010-07-27|2014-09-04|Microptix Technologies, Llc|Spectroradiometer device and applications of same|
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    ES201830758A|ES2738912B2|2018-07-25|2018-07-25|REAL-TIME MEASUREMENT SYSTEM OF THE ATMOSPHERIC ATTENUATION OF AN ELECTROMAGNETIC RADIATION FROM AT LEAST ONE SOURCE AND MEASUREMENT METHOD|ES201830758A| ES2738912B2|2018-07-25|2018-07-25|REAL-TIME MEASUREMENT SYSTEM OF THE ATMOSPHERIC ATTENUATION OF AN ELECTROMAGNETIC RADIATION FROM AT LEAST ONE SOURCE AND MEASUREMENT METHOD|
    EP19778562.9A| EP3799620A1|2018-07-25|2019-07-25|System for the real-time high precision measurement of the atmospheric attenuation of electromagnetic radiation from at least one source|
    CN201980047548.2A| CN112437871A|2018-07-25|2019-07-25|System for real-time high-precision measurement of atmospheric attenuation of electromagnetic radiation from at least one source|
    PCT/ES2019/070522| WO2020021146A1|2018-07-25|2019-07-25|System for the real-time high precision measurement of the atmospheric attenuation of electromagnetic radiation from at least one source|
    US17/262,348| US20210223101A1|2018-07-25|2019-07-25|System for the real-time high precision measurement of the atmospheric attenuation of electromagnetic radiation from at least one source and method for measurement|
    CL2021000110A| CL2021000110A1|2018-07-25|2021-01-14|High precision real-time measurement system for atmospheric attenuation of electromagnetic radiation from at least one source and measurement method.|
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