CN104457610A - Solar condenser mirror surface measuring and adjusting method and device - Google Patents

Abstract

The invention relates to a method for measuring and adjusting the mirror surface of a solar concentrator and a device thereof. It mainly includes using photogrammetry to measure the installation position of the mirror sheet, using a three-dimensional scanner to measure the surface shape of the small dish mirror, and simulating and evaluating the light-gathering effect of the entire light-gathering system. The three-dimensional coordinates of the marking points pasted on the mirror sheet are obtained by photogrammetry, and the installation error of the mirror sheet is calculated by using the three-dimensional rigid body motion algorithm, and the mirror sheet is adjusted accordingly. A three-dimensional scanner is used to measure the surface shape of the mirror surface, and compared with the theoretical design, the slope error of the actual mirror surface is calculated. Combining the measurement results of the installation error and the slope error of the mirror sheet, simulate and evaluate the concentrating effect of the entire concentrating system. And the mirror surface can be measured again so as to further reduce the installation error and improve the light-gathering effect.

Description

Method and device for measuring and adjusting mirror surface of solar concentrator

technical field

The invention relates to the field of solar thermal power generation, in particular to a method for measuring and adjusting the mirror surface of a solar concentrator and a device thereof.

Background technique

The total global solar radiation is about 1.7×10 ¹⁷ W, of which China accounts for about 1% (1.8×10 ¹⁵ W, equivalent to 1.9 trillion tons of standard coal per year), which is 680 times the current annual energy consumption in China. It has huge potential for development.

Solar power generation technologies are mainly divided into two categories: photovoltaic power generation and photothermal power generation. Photovoltaic power generation mainly uses the photoelectric effect of photovoltaic panels to generate electricity. There are currently three main disadvantages in this technology: (1) The generated power varies with the intensity of sunlight, so it cannot generate power at night and in rainy days, which has a great impact on the power grid; The area of the photovoltaic panel is large, and the manufacturing process of the photovoltaic panel is seriously polluted and the cost is high; (3) The response band of the photovoltaic panel to the solar spectrum is mainly concentrated in the high-frequency short-wave region (400<λ<1100nm), and the low-frequency long-wave region Most of the energy is converted into heat, resulting in an increase in the temperature of the photovoltaic panel, a decrease in photoelectric conversion efficiency, and a shortened service life.

Photothermal power generation technology mainly uses parabolic reflectors (or Fresnel reflectors) to gather sunlight, and generates steam or heated fluid to drive engines (such as steam turbines, Stirling machines, etc.) through photothermal conversion and heat exchange devices. Power generation; its advantage is that this technology can absorb full-band sunlight, and can realize continuous power generation day and night through heat storage. Due to the low energy flux density of solar energy, it is necessary to gather sunlight through a concentrator system to obtain high energy flux density and heat collection temperature. Concentrating systems are mainly divided into four categories: trough type, linear Fresnel type, tower type and dish type. Among them, the trough mirror gathers sunlight on a line parallel to the mirror surface, and this technology only performs one-dimensional tracking of sunlight. The linear Fresnel type is similar to the trough type. The parabolic trough type concentrator is divided into multiple strip-shaped mirrors, which helps to reduce costs. The tower type of concentrator usually uses many heliostats to gather sunlight at the top of the tower. On the collector, the system occupies a large area, the orientation and surface of each heliostat are different, and the control system is complicated. Dish concentrating is usually composed of an integral rotating parabolic mirror or multiple mirrors, which can concentrate sunlight in a small area, and the floor area and concentration ratio can be flexibly adjusted. In order to improve the concentrating effect, the concentrating mirror should be installed on the bracket according to the theoretical design as far as possible, but due to the huge area of the mirror system, it is difficult to install the theoretical design accurately. Especially for the dish type and tower type with high concentration ratio, in order to meet the requirements of high concentration ratio and high temperature heat collection, the installation and adjustment of the condenser mirror have high requirements. Taking the dish Stirling system as an example, it is currently the most efficient (31.25% peak record) among various solar thermal power generation systems. Its technical focus lies on the concentrator with high concentration ratio and the high-efficiency Stirling engine. The concentrator system must provide solar energy with a high concentration ratio to supply the thermal head of the Stirling engine, and ensure that the energy flow density distribution is as uniform as possible to avoid burning the thermal head of the Stirling engine and causing accidents. Possibly high concentration ratio to reduce heat loss. Therefore, the accurate installation and adjustment of the condenser mirror is one of the keys to the efficient and reliable operation of the dish system. Due to the large area of the current large-scale dish-type concentrating system, the mirror panel cannot be formed at one time. It needs to be installed on the dish-type mirror bracket by many small mirror panels, and the whole is assembled into a large dish-type mirror. There is an adjustment mechanism to adjust the mirror installation position. The dish condenser has a large area and a large number of mirrors, which brings great difficulties to the measurement and adjustment of the mirror. Similarly, there is also the difficulty of mirror installation and adjustment for the slot type, linear Fresnel type and tower type.

At present, the main adjustment method is real-time adjustment under the sunlight. With manual experience, the mirror is adjusted so that the focused spot of sunlight reflected by the mirror enters the receiver, which is blind and time-consuming. In addition, there is the fringe measurement method, which requires a large fringe screen, and the fringe screen must be installed and positioned accurately. In addition, a camera is required to collect and process the reflected fringes. The difficulty of this method is that the measurement results need to be analyzed. Calibration is currently under study. There is also the conventional method of performing precise installation and positioning during the manufacturing process, but it is not suitable for the condenser system with a large area.

Contents of the invention

Aiming at the difficulties of measuring, positioning and adjusting due to the complex mirror surface shape and the large number of mirrors in the solar thermal power concentrating system, a solar concentrator mirror measuring and adjusting device and its method are proposed.

A device for measuring and adjusting the mirror surface of a solar concentrator, including a mirror bracket, a mirror sheet, a connection adjustment mechanism, an identification point, a camera, a length calibration rod A, a length calibration rod B and a processor. The identification points are attached to the mirror sheet, and the mirror sheet The camera is connected to the processor through the camera data cable, and the length calibration rod A and the length calibration rod B are placed non-parallel.

The solar concentrator includes at least one concentrator mirror sheet, and the solar concentrators are dish-type, trough-type, linear Fresnel-type and tower-type concentrators.

More than two connection adjustment mechanisms are arranged on the back of the mirror sheet of the solar concentrator.

The device also includes a laser scanner, and the laser scanner is connected to the processor through a laser scanner data line.

A method for measuring and adjusting the mirror surface of a solar concentrator comprises steps:

1) Preliminarily install the concentrator mirror sheet 1 on the mirror support of the solar concentrator through the connection adjustment mechanism;

2) Paste more than 3 marking points on each condenser mirror that needs to be measured and adjusted;

3) Place non-parallel length calibration rod A and length calibration rod B on the solar concentrator;

4) Use the camera to take pictures of the marking points, the length calibration rod A and the length calibration rod B from different directions, the collected data is transmitted to the processor through the camera data to calculate the relative position of each marking point, and use the length calibration rod A Calibrate with the actual length of the length calibration rod B to obtain the actual three-dimensional coordinates of each mark point on all mirror surfaces;

5) Through the rigid body motion algorithm, the actual installation position of each mirror is calculated according to the three-dimensional coordinates of the marked points, and the installation error is calculated;

6) According to the installation error obtained in step 5), calculate the amount to be adjusted according to the connection adjustment mechanism, and then adjust the condenser mirror to reduce the installation error.

When the concentrating ratio of the concentrator does not reach the design value, repeat steps 4) to 6) after step 6) to further reduce the mirror installation error until the concentrating ratio of the concentrator reaches the design value.

Described a kind of solar concentrator mirror measurement, adjustment method also comprises step A), and described step A) is to utilize laser three-dimensional scanner, scans single mirror sheet, measures the shape error of single mirror sheet, and with error Probabilistic models are represented.

Described a kind of solar concentrator mirror measurement, adjustment method also comprises step 7), and described step 7) is according to the mirror sheet installation error that obtains measurement and the shape error of described single mirror sheet, to the whole concentrator The light-gathering effect of the system is evaluated.

Steps 2) to 4) are based on the principle of photogrammetry. The marking point is a target point with a fixed shape that can be recognized by the camera. The actual operation is to paste the marking point on the mirror to ensure that each mirror sheet has 3 or more Marking points, and the marking points can be randomly distributed on the mirror sheet, and do not need to be attached to a specific position on the mirror sheet. The camera shoots the marking points, the length calibration rod A and the length calibration rod B from different directions, and the relative position of each marking point can be calculated by using the two-dimensional picture according to the principle of conventional photogrammetry, and then the marking point is obtained according to the length calibration rod Therefore, the absolute three-dimensional coordinates of the discrete marker points are obtained through the above steps.

Step 5) is to calculate the installation error according to the rigid body motion algorithm, let X be the coordinate matrix of the marker point when the theoretical installation error is zero, R be the cosine matrix, ΔX be the translation matrix, and X' be the three-dimensional coordinate matrix of the marker point obtained by measurement, so When the theoretical installation error is zero, the following equation is satisfied:

XR+ΔX=X'

By simple transformation, we can get,

X=(X'-ΔX)R ^-1

Among them, R ^-1 represents the inverse matrix of R, let F be the expression of the theoretical mirror shape function, we can get,

F(X)=F((X'-ΔX)R ^-1 )

Due to the slight deformation of the mirror surface, processing error and measurement error, etc., the above formula cannot be completely equal, so the minimum value of R and ΔX is found through the optimization algorithm, so that the sum of the absolute value of the error between the theoretical design value and the calculated value of the measurement result is the smallest. As shown in the following formula.

min(Σ|F(X)-F((X′-ΔX)R ^-1 )|)

The R and ΔX values obtained from the above formula are the installation deviation. Step 6) According to the specific values of the calculated cosine matrix and translation matrix, the adjustment amount of the installation adjustment mechanism of the mirror sheet is calculated, and then adjusted to reduce the installation error of the mirror surface.

The overall installation error of the mirror sheet is obtained by the above method. In order to further measure and evaluate the concentrating system, a laser scanner is added to scan and measure a single mirror to obtain the actual shape of a single mirror, and to fit the shape of the mirror to obtain the probability distribution function of its shape error, and use Rayleigh The probability distribution function is expressed as follows,

$\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; x</span>}}{{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; x</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}}$

In the above formula, x is the shape error, and σ is the standard shape error.

Combined with the installation error and the shape error of a single mirror, the light-condensing effect of the light-condensing system is calculated through the processor simulation, and the entire light-condensing system is further evaluated.

Compared with the prior art, the present invention has the following advantages:

1. A rigid body motion matrix algorithm is proposed for the three-dimensional positioning of large-scale and complex concentrating mirrors, which can accurately and quickly calculate the spatial position and installation error of each concentrating mirror, and cooperate with the mirror adjustment mechanism to reduce mirror installation errors;

2. Compared with the real-time spotlight adjustment method under the sun, it has obvious advantages such as high adjustment accuracy and time saving, which improves safety, saves labor costs, and improves efficiency. Compared with the stripe reflection method, this method is relatively simple to operate and does not require calibration , accurate data can be obtained, and it is accurate three-dimensional data, which is easy to calculate the adjustment amount required by the subsequent adjustment mechanism;

3. Combined with three-dimensional scanning to measure the one-sided shape of a single mirror, and calculate the shape error of the mirror, it can accurately simulate and evaluate the concentrating effect of the entire concentrating system, and repeat steps 4, 5 and 6 again for the mirror The lens is measured and adjusted again to further reduce the installation error and improve the light-gathering effect.

Description of drawings

Figure 1 is a schematic diagram of a light concentrating system composed of multiple mirror sheets;

Figure 2 is a schematic cross-sectional view of the mirror bracket, mirror sheet and connection adjustment mechanism

Fig. 3 is a schematic diagram of marking points attached to the mirror;

Fig. 4 is the measuring schematic diagram of the present invention;

Fig. 5 is the measurement schematic diagram after the scanner is added in the present invention;

Figure 6 is a schematic flow chart of the steps.

The serial number names in the figure are: 1. Condenser mirror sheet, 2. Marking point, 3. Laser scanner, 4. Laser scanner data line, 5. Processor, 6. Camera data line, 7. Camera, 8, Length calibration rod A, 9, length calibration rod B, 10, connection adjustment mechanism, 11, mirror bracket

Detailed ways

As shown in the figure: a method for measuring and adjusting the mirror surface of a solar concentrator includes steps:

1) Preliminarily install the concentrator mirror sheet 1 on the mirror support 11 of the solar concentrator by connecting the adjustment mechanism 10;

2) Paste more than 3 marking points 2 on each concentrator mirror sheet 1 that needs to be measured and adjusted;

3) Place non-parallel length calibration rod A8 and length calibration rod B9 on the solar concentrator;

4) Use the camera 7 to take pictures of the marking point 2, the length calibration rod A8 and the length calibration rod B9 from different directions, and the collected data is transmitted to the processor 5 through the camera data 6 to calculate the relative position of each marking point 2, and Utilize the actual lengths of the length calibration rod A8 and the length calibration rod B9 to calibrate to obtain the actual space three-dimensional coordinates of each mark point 2 on all mirror surfaces;

5) Through the rigid body motion algorithm, the actual installation position of each mirror is calculated according to the three-dimensional coordinates of the marked points, and the installation error is calculated;

6) According to the installation error obtained in step 5), the amount to be adjusted is calculated according to the connection adjustment mechanism 10, and then the concentrator mirror sheet 1 is adjusted to reduce the installation error.

The solar concentrator includes at least one concentrator mirror sheet 1, and the solar concentrators are dish-type, trough-type, linear Fresnel-type and tower-type concentrators.

The solar concentrator mirror sheet 1 is provided with more than two connection adjustment mechanisms 10 on the back.

When the concentrating ratio of the concentrator does not reach the design value, repeat step 4)-step 6) after step 6) to further reduce the mirror installation error until the concentrating ratio of the concentrator reaches the design value.

Described a kind of solar concentrator mirror measurement, adjustment method also comprises step A), and described step A) is to utilize laser three-dimensional scanner 3 to scan single mirror sheet 1, measure the shape error of single mirror sheet, and Characterized by an error probability model.

Described a kind of solar concentrator mirror measurement, adjustment method also comprises step 7), and described step 7) is according to the mirror sheet installation error that is measured and the shape error of described single mirror sheet, to the whole concentrator The light-gathering effect of the optical system is evaluated.

Implement the solar concentrator mirror measurement of method as claimed in claim 1, adjustment device, comprise mirror support 11, mirror sheet 1, connection adjustment mechanism 10, mark point 2, video camera 7, length calibration rod A8, length calibration rod B9 and The processor 5, the marking point 2 is pasted on the mirror sheet 1, the mirror sheet 1 is installed on the mirror bracket 11 through the connection adjustment mechanism 10, the camera 7 is connected to the processor 5 through the camera data line 6, the length calibration rod A8 and the length calibration Bar B9 is placed non-parallel.

The device also includes a laser scanner 3 , and the laser scanner 3 is connected to the processor 5 through a laser scanner data line 4 .

The condenser mirror sheet 1 is installed on the mirror bracket 11 through the connection adjustment mechanism 10, as shown in FIG. 2 . As shown in FIG. 1 , when all the condenser mirror sheets 1 are installed on the bracket 11 , three or more marking points 2 are pasted on each mirror sheet, as shown in FIG. 3 . Put two length calibration rods A and B near the spotlight system, so that the two length calibration rods are placed non-parallel, use the camera 7 to shoot the marking points and the two length calibration rods from different directions, and the data is passed through the camera data line 6 is transmitted to the processor 5 to process the data, and the actual three-dimensional coordinates of the marked points are obtained, as shown in FIG. 4 .

The installation error is calculated by applying the matrix algorithm of rigid body motion. Let X be the coordinate matrix of the marker points when the theoretical installation error is zero, R be the cosine matrix, ΔX be the translation matrix, and X' be the three-dimensional coordinate matrix of the marker points measured, so when the theoretical installation error is zero, the following equation is satisfied :

XR+ΔX=X'

By simple transformation, we can get,

X=(X'-ΔX)R ^-1

Among them, R ^-1 represents the inverse matrix of R, let F be the expression of the theoretical mirror shape function, we can get,

F(X)=F((X'-ΔX)R ^-1 )

Due to the slight deformation of the mirror surface, processing error and measurement error, etc., the above formula cannot be completely equal, so the minimum value of R and ΔX is found through the optimization algorithm, so that the sum of the absolute value of the error between the theoretical design value and the calculated value of the measurement result is the smallest. As shown in the following formula.

min(Σ|F(X)-F((X′-ΔX)R ^-1 )|)

The R and ΔX values obtained from the above formula are the installation deviation. Step 6) According to the specific values of the calculated cosine matrix and translation matrix, the adjustment amount of the installation adjustment mechanism of the mirror sheet is calculated, and then adjusted to reduce the installation error of the mirror surface.

The overall installation error of the mirror sheet is obtained by the above method. In order to further measure and evaluate the concentrating system, a laser scanner is added to scan and measure a single mirror to obtain the actual shape of a single mirror, and to fit the shape of the mirror to obtain the probability distribution function of its shape error, and use Rayleigh The probability distribution function is expressed as follows,

$\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; x</span>}}{{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; x</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}}$

In the above formula, x is the shape error, and σ is the standard shape error.

Combined with the installation error and the shape error of a single mirror, the light-gathering effect of the light-gathering system is simulated and calculated by the processor, and the entire light-gathering system is further evaluated. The flow chart is shown in Figure 6.

Claims (8)

1. a solar concentrator mirror surface measurement, adjustment method, is characterized in that comprising steps: 1) Preliminarily install the concentrator mirror sheet (1) on the mirror bracket (11) of the solar concentrator through the connection adjustment mechanism (10); 2) Paste more than 3 marking points (2) on each concentrator mirror sheet (1) that needs to be measured and adjusted; 3) Place non-parallel length calibration rod A (8) and length calibration rod B (9) on the solar concentrator; 4) Use the camera (7) to take pictures of the marking point (2), the length calibration rod A (8) and the length calibration rod B (9) from different directions, and the collected data is transmitted to the processor (5) through the camera data (6) Calculate the relative position of each marking point (2) on the surface, and use the actual length of the length calibration rod A (8) and the length calibration rod B (9) to calibrate to obtain the actual position of each marking point (2) on all mirrors. Space three-dimensional coordinates; 5) Through the rigid body motion algorithm, the actual installation position of each mirror is calculated according to the three-dimensional coordinates of the marked points, and the installation deviation is calculated; 6) According to the installation deviation obtained in step 5), calculate the amount to be adjusted according to the connection adjustment mechanism (10), and then adjust the condenser mirror (1) to reduce the installation error. 2. A solar concentrator mirror measurement and adjustment method according to claim 1, characterized in that the solar concentrator includes at least one concentrator mirror sheet (1), and the solar concentrator is a dish trough, linear fresnel and tower concentrators. 3. A solar concentrator mirror measurement and adjustment method according to claim 2, characterized in that two or more connection adjustment mechanisms (10) are arranged on the back of the solar concentrator mirror sheet (1). 4. A method for measuring and adjusting the mirror surface of a solar concentrator according to claim 1, characterized in that after implementing the steps 1) to 6), when the concentration ratio of the concentrator does not reach the design value, the After step 6), repeat steps 4) to 6) to further reduce the mirror installation error until the concentration ratio of the concentrator reaches the design value. 5. The method for measuring and adjusting the mirror surface of a solar concentrator according to claim 1, characterized in that it also includes step A), and the step A) is to use a laser three-dimensional scanner (3) to scan a single concentrator The mirror sheet (1) is scanned, the shape error of a single mirror sheet is measured, and the error probability model is used to characterize it. 6. A solar concentrator mirror measurement and adjustment method according to claims 1 and 5, characterized in that it also includes step 7), and said step 7) is based on the measured installation error of the mirror sheet and the obtained The shape error of the single mirror sheet mentioned above is used to evaluate the concentrating effect of the entire concentrating system. 7. A solar concentrator mirror measurement and adjustment device implementing the method according to claim 1, characterized in that it includes a mirror bracket (11), a mirror sheet (1), a connection adjustment mechanism (10), and a marking point (2 ), the camera (7), the length calibration rod A (8), the length calibration rod B (9) and the processor (5), the marking point (2) is pasted on the mirror sheet (1), and the mirror sheet (1) is connected by The adjustment mechanism (10) is installed on the mirror bracket (11), the camera (7) is connected to the processor (5) through the camera data cable (6), the length calibration rod A (8) and the length calibration rod B (9) are not placed in parallel. 8. A solar concentrator mirror measurement and adjustment device according to claim 7, characterized in that the device also includes a laser scanner (3), and the laser scanner (3) passes the laser scanner data Wire (4) is connected to processor (5).