CONCENTRATING SOLAR POWER PLANT

Abstract

This solar power plant (1) comprises: - a solar receiver (2); - a set of reflectors (3), each having a predetermined position; each reflector (3) comprising a solar tracker (4); - control means, configured to assign a setpoint position to each solar tracker (4); notable in that it comprises: - transmitting means (5), arranged to transmit an identification signal (sid) of a selected reflector (3a); - receiving means (6), arranged to receive the identification signal (sid), and configured to deliver a detection signal to the control means when the selected reflector (3a) has the corresponding predetermined position; and in that the control means are configured to adjust the setpoint position assigned to the solar tracker (4) of the selected reflector (3a), until the detection signal is delivered to the control means by the receiving means (6).

Description

technical field

[0001] The invention relates to the technical field of concentrated solar power plants, in particular thermodynamic solar power plants or photovoltaic solar power plants. The invention is applicable whenever the solar power plant uses reflectors to concentrate a solar flux. Prior art

[0002] A concentrating solar power plant known from the prior art, in particular from documents CN 104699116, CN 103034244, CN 104156003, comprises: a solar receiver; an array of reflectors, each having a predetermined position such that the array of reflectors reflects an incident solar flux towards the solar receiver; each reflector comprising a solar tracker; control means, configured to assign a setpoint position to each solar tracker in which the corresponding reflector is intended to present the corresponding predetermined position.

[0003] In a concentrated solar power (CSP) plant, the solar receiver, also called the central receiver, converts the solar flux reflected by all the reflectors into sensible heat. A heat transfer fluid typically circulates within the solar receiver. There are different types of solar receivers, such as pressurized air receivers, direct absorption receivers, surface absorption receivers, and volumetric receivers.

[0004] In the case of a photovoltaic solar power plant, the solar receiver is one or more photovoltaic panels.

[0005] The term "concentrating" comes from the fact that the reflectors are arranged to concentrate the incoming solar flux onto the solar receiver. There are different types of reflectors, for example heliostats, Fresnel mirrors, or parabolic trough mirrors.

[0006] Solar trackers (“ trackers » in English) allow us to follow the sun's path throughout the day.

[0007] The predetermined positions of all the reflectors are theoretical positions that are perfectly known insofar as the position of the sun is perfectly known for a given location on Earth.

[0008] Such a state-of-the-art solar power plant is not entirely satisfactory because the actuators of the solar trackers generally lack sufficient mechanical precision (or do so at prohibitive cost) to achieve a perfect match between the target position and the theoretical predetermined position. Correction systems exist in the state of the art, but these systems require either interrupting the operation of the solar power plant or deploying bulky and cumbersome equipment such as gyroscopes.

[0009] Document US2010 / 0139644 discloses a solar power plant in which heliostats are controlled by a first control circuit that communicates via wired or wireless connections with two other control circuits. Communication between the first control circuit and the two other control circuits uses routers.

[0010] Documents DE 10 2007 050031 and US 2012 / 279485 also disclose such a solar power plant. Description of the invention

[0011] The invention aims to remedy, in whole or in part, the aforementioned drawbacks. To this end, the invention relates to a concentrated solar power plant, comprising: a solar receiver; an array of reflectors, each having a predetermined position such that the array of reflectors reflects an incident solar flux towards the solar receiver; each reflector comprising a solar tracker, the incident solar flux having a spectrum; control means, configured to assign a setpoint position to each solar tracker in which the corresponding reflector is intended to present the corresponding predetermined position; The solar power plant is remarkable in that it includes: emission means modifying the spectrum of the incident solar flux so as to emit a modified spectrum defining the identification signal of a reflector chosen from the set of reflectors, emission means comprising an element absorbing part of the spectrum of the incident solar flux so as to emit an absorption spectrum defining the identification signal or comprising an element reflecting part of the spectrum of the incident solar flux so as to emit a reflection spectrum defining the identification signal, or emission means configured so that the identification signal Sid is a visual signature for example with rhythmic modulations of the Morse type or emission means configured so that the identification signal includes mechanical vibrations;receiving means, arranged to receive the identification signal, and configured to deliver a detection signal to the control means when the chosen reflector presents the corresponding predetermined position; and in that the control means are configured to adjust the setpoint position assigned to the solar tracker of the selected reflector, until the detection signal is delivered to the control means by the receiving means.

[0012] Thus, such a concentrating solar power plant according to the invention makes it possible to ensure a permanent, continuous adjustment of the target position relative to the theoretical predetermined position, without requiring the plant to stop operating. This adjustment occurs even if the chosen reflector is shaded. Furthermore, the use of an identification signal with transmitting / receiving means is a simple and inexpensive solution compared to prior art solutions. In other words, the transmitting / receiving means assist the solar tracker of the chosen reflector to maintain or maximize aiming accuracy, for example, in the presence of wind or mechanical loss of precision.

[0013] The solar power plant according to the invention may include one or more of the following characteristics.

[0014] According to one feature of the invention, the emission means are mounted on the solar tracker of the chosen reflector.

[0015] Thus, one advantage is that the reflectors are not obstructed by the emission means, thereby avoiding a reduction in their active surface area. The relative position of the reflector with respect to the solar tracker is perfectly known.

[0016] According to a feature not covered by the invention, the identification signal includes electromagnetic radiation.

[0017] Thus, one advantage provided by electromagnetic radiation is that it is not very sensitive to weather conditions, and can be adapted to the distances from the power plant by a wise choice of wavelength or range of wavelengths.

[0018] According to one feature of the invention, the incident solar flux has a spectrum, and the emission means modify the spectrum of the incident solar flux so as to emit a modified spectrum defining the identification signal.

[0019] Thus, one advantage provided by using the incident solar flux as the starting point for the identification signal is the simplicity of implementation, in the absence of bulky or complex equipment to deploy on an existing solar power plant.

[0020] According to one feature of the invention, the emission means comprise an element absorbing a portion of the spectrum of the incident solar flux so as to emit an absorption spectrum defining the identification signal.

[0021] Thus, one advantage provided by an absorption spectrum is to simply define an identification signal that is characteristic and discriminating, and can also be easily detected.

[0022] According to one feature of the invention, the absorbing element is selected from the group comprising a layer of a colored polymer, a layer of paint, a layer of a particle-loaded matrix.

[0023] Thus, one advantage provided by these absorbing elements is the ease of implementation on an already existing solar power plant.

[0024] According to one feature of the invention, the emission means comprise an element reflecting a part of the spectrum of the incident solar flux so as to emit a reflection spectrum defining the identification signal.

[0025] Thus, one advantage provided by a reflection spectrum is to simply define an identification signal that is characteristic and discriminating, and can also be easily detected.

[0026] According to one feature of the invention, the reflective element comprises a surface of a metallic material, preferably selected from the group comprising Ag, Cu, Al, a steel.

[0027] Thus, one advantage provided by these reflective elements is the ease of implementation on an already existing solar power plant.

[0028] According to one feature of the invention, the receiving means comprise a spectroradiometer or a spectrophotometer.

[0029] Thus, one advantage provided is the ability to easily detect electromagnetic radiation by its spectral signature.

[0030] According to one feature of the invention, the identification signal includes mechanical vibrations.

[0031] Thus, one advantage is the ability to distinguish a reflector using acoustic waves. Depending on the solar power plant's environment, it may be beneficial to favor acoustic waves over electromagnetic waves, for example, due to electromagnetic compatibility requirements. Brief description of the drawings

[0032] Other features and advantages will become apparent in the detailed description of different embodiments of the invention, the description being accompanied by examples and reference to the accompanying drawings. Figure 1 is a schematic view of a solar power plant according to the invention. Figure 2a is a graph illustrating the solar spectrum (ordinates: arbitrary unit of irradiance; abscissas: wavelength in microns). Figure 2bis a graph illustrating the solar spectrum modified by means of emitting a reflector identification signal (ordinates: arbitrary unit of irradiance; abscissas: wavelength in microns). Detailed description of the implementation methods

[0033] Identical elements or elements performing the same function will bear the same references for the different embodiments, for the sake of simplification.

[0034] One object of the invention is a concentrating solar power plant 1, comprising: a solar receiver 2; an array of reflectors 3, each having a predetermined position such that the array of reflectors 3 reflects an incident solar flux FS towards the solar receiver 2; each reflector 3 comprising a solar tracker 4; control means, configured to assign a setpoint position to each solar tracker 4 in which the corresponding reflector 3 is intended to present the corresponding predetermined position; Solar power plant 1 is remarkable in that it includes: transmission means 5, arranged to emit an identification signal S id of a selected reflector 3a from the set of reflectors 3; reception means 6, arranged to receive the identification signal S id, and configured to deliver a detection signal to the control means when the selected reflector 3a presents the corresponding predetermined position; and in that the control means are configured to adjust the setpoint position assigned to the solar tracker 4 of the selected reflector 3a, until the detection signal is delivered to the control means by the receiving means 6. Solar power plant

[0035] Solar power plant 1 could be a concentrating solar power plant. Concentrating solar power plant 1 could be of the thermodynamic type. Solar power plant 1 could be a concentrating photovoltaic solar power plant.

[0036] In the case of a concentrating solar power plant 1, the solar receiver 2, also called the central receiver, converts the solar flux FS reflected by all the reflectors 3 into heat, preferably sensible heat. A heat transfer fluid typically circulates within the solar receiver 2. When the concentrating solar power plant 1 is of the thermodynamic type, the heat transfer fluid serves as the heat source in a thermodynamic cycle. There are different types of solar receiver 2, for example, pressurized air receivers, direct absorption receivers, surface absorption receivers, or volumetric receivers.

[0037] In the case of a concentrated photovoltaic solar power plant 1, the solar receiver 1 is formed by one or more photovoltaic panels. Reflectors

[0038] The term "concentrating" comes from the fact that the set of reflectors 3 is arranged to concentrate the incident solar flux FS onto the solar receiver 2. The reflectors 3 are advantageously heliostats, Fresnel mirrors, or parabolic trough mirrors. When the reflectors 3 are heliostats, the solar receiver 2 is advantageously located at the top of a tower.

[0039] Solar trackers 4 (“ trackers » in English) are adapted to follow the sun's path during the day, and thus maximize the incident solar flux FS received by the reflectors 3. The set of reflectors 3 and the corresponding solar trackers 4 are advantageously mechanically joined.

[0040] The predetermined positions of the set of reflectors 3 are theoretical positions that are perfectly known insofar as the position of the sun is perfectly known for a given location on Earth. Means of emission

[0041] The emitting means 5 are advantageously mounted on the solar tracker 4 of the selected reflector 3a. Of course, the emitting means 5 can be fitted to several selected reflectors 3a, provided that the identification signals Sid discriminate between the selected reflectors 3a. However, it is possible to use the same identification signal Sid for several reflectors 3, provided that they have sufficiently discriminating positions. By way of non-limiting examples, the emitting means 5 can be fitted to lines of reflectors 3 (mirrors or heliostats). The emitting means 5 can also be fitted to all the reflectors 3 of the solar power plant 1.

[0042] The emitting means 5 are advantageously arranged so that the angle of reflection of the identification signal S id is different from the angle of reflection of the solar flux FS reflecting off the chosen reflector 3a. The emitting means 5 are advantageously arranged so as not to be shaded.

[0043] The identification signal Sid advantageously incorporates electromagnetic radiation. The incident solar flux FS has a spectrum S0, and the emission means 5 advantageously modify the spectrum S0 of the incident solar flux FS so as to emit a modified spectrum Sid defining the identification signal. As illustrated in the figure 2a The S0 spectrum of the solar flux FS extends mainly between 250 nm and 2500 nm. As illustrated in the figure 2bTherefore, the modified spectrum Sid must fall between 250 nm and 2500 nm. The modified spectrum Sid can be continuous or discontinuous. By way of non-limiting examples, the modified spectrum Sid can be: continuous between 1500 nm and 1750 nm, continuous between 275 nm and 500 nm, then between 1000 nm and 1100 nm.

[0044] The emission means may include an absorbing element 5 that absorbs a portion of the spectrum S0 of the incident solar flux FS so as to emit an absorption spectrum Sid defining the identification signal. In other words, the absorbing element 5 can operate in transmission or reflection of the incident solar flux FS after absorbing certain wavelengths. The absorbing element 5 is advantageously selected from the group comprising a layer of a colored polymer, a layer of paint, or a layer of a particle-loaded matrix. The absorbing element 5 may be produced by a surface treatment that provides a wavelength-filter function. In the case of a particle-loaded matrix, the matrix may be made of any material such as SiO2 or polymethyl methacrylate (PMMA). The particles of the load, preferably inorganic, are chosen to absorb the portion of the spectrum S0 of the solar flux FS.

[0045] The emitting means may include a reflective element 5 that reflects a portion of the spectrum S0 of the incident solar flux FS so as to emit a reflection spectrum Sid defining the identification signal. The reflective element 5 advantageously comprises a surface of a metallic material, preferably selected from the group comprising Ag, Cu, Al, and steel. The surface of the metallic material may advantageously undergo a treatment such as polishing to enhance its reflective properties. These metallic materials possess sufficiently discriminating reflection spectra over the spectral range between 250 nm and 2500 nm. For example, it is possible to discriminate the reflection spectra of Ag and Al between 700 nm and 1000 nm. It is also possible to coat the metallic surfaces with an antireflective layer to modify the reflection spectrum and obtain a set of identification signals Sid.A metallic surface is preferred in order to tend towards specular reflection (therefore very little diffuse) in order to facilitate the subsequent detection of the identification signal S id.

[0046] According to one alternative, the identification signal S id may contain mechanical vibrations. It could therefore be an acoustic signal. According to other alternatives, the identification signal S id may be a visual signature, for example, of rhythmic modulations such as Morse code. Means of reception

[0047] The receiving means advantageously include a spectroradiometer 6 or a spectrophotometer 6. The receiving means advantageously measure the spectral irradiance (e.g., in W / m² / nm) of the identification signal Sid per wavelength. In other words, the receiving means are capable of detecting the spectral signature corresponding to the selected reflector 3a.

[0048] The receiving means 6 may be arranged near the solar receiver 2. The receiving means 6 may also be arranged at a distance from the solar receiver 2, with or without a mechanical connection to the solar receiver 2, provided that their relative position is perfectly known, in order to protect them from the high temperatures near the solar receiver 2. The receiving means 6 preferably do not have a mechanical connection to the solar receiver 2 when the solar receiver 2 has a fixed position over time, for example, within a concrete solar tower. The receiving means 6 preferably have a mechanical connection to the solar receiver 2 when the solar receiver 2 has a position that is likely to change over time, for example, when it is guyed. Detection of the identification signal

[0049] The objective is to maximize the spectral response of the receiving means 6 over the spectral range of the spectrum modified S id by the transmitting means 5. As an example, it is possible to modify the alignment of the lines of reflectors 3 (mirrors or heliostats) according to said spectral range of the spectrum modified S id by the transmitting means 5, when the detection threshold is not satisfactory.

[0050] The receiving means 6 advantageously deliver the detection signal by spectral recognition. More precisely, by way of example, the spectral recognition of the identification signal S id is performed by comparing the measured normalized spectrum with the normalized spectrum previously entered as a reference for different identification signals S id (when it is desired to identify several reflectors 3). This spectral recognition is advantageously performed over the spectral range of the modified spectrum S id by the transmitting means 5, with a sufficiently small wavelength step to establish reliable discrimination. Adjusting the setpoint position

[0051] The control means advantageously adjust the setpoint position by performing feedback loops until the detection signal is delivered to the control means by the receiving means 6. This may involve an iterative search for a maximum energy by successive variations in the alignment of the chosen reflector 3a.

[0052] The control means are advantageously configured to control actuators of the solar tracker 4, the actuators being motors, cylinders etc.

[0053] The invention is not limited to the embodiments described. A person skilled in the art is able to consider their technically operative combinations and to substitute equivalents for them.

Claims

1. Concentrated solar power plant (1) comprising: - a solar receiver (2); - a set of reflectors (3) each having a predefined position so that the set of reflectors (3) reflects an incident solar flux (FS) to the solar receiver (2); each reflector (3) comprising a solar tracker (4), the incident solar flux (FS) comprising a spectrum (So) ; - control means configured to assign a setpoint position to each solar tracker (4) in which the corresponding reflector (3) is designed to present the corresponding predefined position; the solar power plant (1) being characterised in that it comprises: - transmitting means (5) modifying the spectrum (So) of the incident solar flux (FS) so as to emit a modified spectrum defining the identification signal (Sid) of a reflector (3a) chosen from the set of reflectors (3), the transmitting means (5) comprising an element absorbing a part of the spectrum (So) of the incident solar flux (FS) so as to emit an absorption spectrum defining the identification signal (Sid) or comprising an element reflecting a part of the spectrum (So) of the incident solar flux (FS) so as to emit a reflection spectrum defining the identification signal (Sid), or transmitting means (5) configured so that the identification signal (Sid) is a visual signature for example with rhythmic modulations of Morse code type or transmitting means (5) configured so that the identification signal (Sid) comprises mechanical vibrations ; - receiving means (6) arranged to receive the identification signal (Sid) and configured to deliver a detection signal to the control means when the chosen reflector (3a) presents the corresponding predefined position; and in that the control means are configured to adjust the setpoint position assigned to the solar tracker (4) of the chosen reflector (3a) until the detection signal is delivered to the control means by the receiving means (6).

2. Solar power plant (1) according to claim 1, wherein the transmitting means (5) are located on the solar tracker (4) of the chosen reflector (3a).

3. Solar power plant (1) according to one of claims 1 and 2, wherein the transmitting means (5) comprise an absorbing element and wherein the absorbing element is selected from the group comprising a layer of coloured polymer, a layer of paint, and a particle-charged matrix layer.

4. Solar power plant (1) according to one of claims 1 and 2, wherein the transmitting means (5) comprise a reflecting element and wherein the reflecting element comprises a surface made from a metallic material, preferably selected from the group comprising Ag, Cu, Al, and a steel.

5. Solar power plant (1) according to one of the foregoing claims, wherein the transmitting means (5) modify the spectrum (So) of the incident solar flux (FS) so as to emit a modified spectrum defining the identification signal (Sid) and wherein the receiving means (6) comprise a spectroradiometer or a spectrophotometer.