CN103175503B - Method for measuring included angle between solar directional direction and optical axis of radiometer - Google Patents

Abstract

The invention relates to a method for measuring the included angle between a solar directional direction and the optical axis of a radiometer, relating to the field of measurement of solar irradiance. In order to solve the problems of inconvenience in operation and errors of the traditional measuring method, the technical scheme is as follows: the method comprises the following steps of: calculating the full field angle, half-intensity field angle and unshielded view field of the radiometer according to the view field design parameters of the radiometer, and delineating the theoretical trapezoidal curve of power response along with the change of an incident angle according to the power response change law of the absolute radiometer on different view fields; installing the radiometer into a solar directional system, and irradiating by utilizing a simulated solar light source; firstly measuring the light source incident angle through the solar directional system, then measuring the power response value of the radiometer at the light source incident angle through the radiometer, and measuring the power response value of the radiometer at different light source incident angles to obtain the normalized trapezoidal curve of the actually-measured power response of the radiometer, along with change of the incident angle; and determining the difference absolute value of an angle corresponding to a vertical line positioned on the bottom midpoint position of the actually-measured normalized trapezoidal curve and an angle corresponding to the symmetric axis of the theoretical trapezoidal curve.

Description

Measure the method for sun pointing direction and radiometer optical axis included angle

Technical field

The present invention relates to solar irradiance fields of measurement, the measuring method of sun pointing direction and radiometer optical axis included angle when being specifically related to use solar tracking mode to measure solar irradiance.

Background technology

Adopt solar tracking mode to measure the method for solar irradiance, be placed on solar tracking system by lumen type absolute radiometer, tracker regulates radiometer direction to make it point to the sun in real time and measures.Tracker is made up of motion, feedback control system and angle output unit (normally sun sensor).Sun sensor adopts pinhole imaging system principle to be imaged onto on area array CCD by the sun in its visual field, the position of CCD initial point is departed from by calculating sun picture, calculate observation solar direction this moment, by feedback control system actuation movement mechanism kinematic, regulate sun pointing direction, until the imaging of the sun on CCD drops on CCD initial point.So far solar tracking system completes Direct to the sun function.Sun sensor Real-time Feedback sun observation angle information, controls sun pointing system and points to the sun in real time.

Lumen type absolute radiometer measures solar irradiance, and radiometer visual field is determined jointly by field stop and key light door screen, as shown in Figure 1.In order to reduce the impact of parasitic light, background radiation equal error item, the very little (θ that radiometer visual field is designed usually ₃≤ 2 °).Subtended angle due to the sun is 0.5 °, if sunshine incident direction departs from radiometer optical axis, not only can introduce too much parasitic light, also can cause and measure less than complete solar radiation, produce inaccurate measurement result.So needs are measured and revised the angle of sun pointing direction and radiometer optical axis, make sun pointing system accurately point to the solar time, sunshine can be incident along radiometer optical axis.

The method of existing measurement sun pointing direction and radiometer optical axis included angle, as seen from Figure 1, radiometer optical axis direction is the direction perpendicular to main stop plane, need first key light door screen plane normal direction to be drawn, by transit survey key light door screen normal direction, then the optical axis of the measurement of angle output unit (normally sun sensor) in sun pointing system is drawn, with its optical axis direction of transit survey, calculated the angle of sun pointing direction and radiometer optical axis by this both direction measured.After radiometer assembling and installation, draw its normal direction become very difficult from main stop plane, need to transform through multilayer, this plane normal direction is changed into the direction being easy to measure, conversion process brings extra error, makes measurement result inaccurate.

Summary of the invention

The present invention in order to solve existing measurement sun pointing direction and lumen type absolute radiometer optical axis included angle measuring method in radiometer optical axis is drawn time the inconvenience that brings and the problem of error, propose a kind of method measuring sun pointing direction and radiometer optical axis included angle, realize simple directly measurement.

Technical scheme of the present invention is as follows:

Measure the method for sun pointing direction and radiometer optical axis included angle, comprise the following steps:

Step one: according to calculation of design parameters radiometer full filed angle 2, radiometer visual field θ ₁, half intensity field angle 2 θ ₂visual field 2 θ is blocked with nothing ₃, according to the power response Changing Pattern of radiometer to different visual field, describe the theoretical step curve that power response changes with incident angle;

Step 2: radiometer is installed in sun pointing system, simulated solar light source is utilized to irradiate, first by sun pointing system measurement light source incident angle θ, then by the radiometer power response value of radiometer measurement under this angle, continuously change light source incidence angle θ, make it at-θ ₁~ θ ₁within change, measuring radiation meter, in the power response value of Different Light incident angle, draws the normalization step curve that the radiometer power response of actual measurement changes with incident angle;

Step 3: the difference determining the angle that the vertical line of the normalization step curve upper base point midway of actual measurement is corresponding and theoretical step curve axis of symmetry corresponding angle, this difference is sun pointing direction and radiometer optical axis included angle.

Beneficial effect of the present invention: measuring method of the present invention, is according to the power response Changing Pattern of absolute radiometer to different visual field, describes the theoretical step curve that power response changes with incident angle, and then determine theoretical curve axis of symmetry corresponding angle; Penetrate the power response value of meter at Different Light incident angle by actual measurement, draw the normalized curve that the radiometer power response of actual measurement changes with incident angle, and then determine the angle that actual measurement step curve upper base mid point is corresponding; Calculate the absolute difference of angle corresponding to actual measurement step curve upper base mid point and theoretical curve axis of symmetry corresponding angle, be sun pointing direction and radiometer optical axis included angle, this method is simple to operate, precision is high, avoid in existing measuring method and need to draw radiometer optical axis and sun pointing direction, the error needing the extra equipment taken measurement of an angle to bring and inconvenience.

Accompanying drawing explanation

Fig. 1 is radiometer visual field schematic diagram.

Fig. 2 is radiometer visual field internal power response change schematic diagram.

Fig. 3 is sun pointing direction and radiometer optical axis included angle computing method schematic diagram.

In figure: 1, theoretical step curve, according to the curve that the radiometer power response that provides of radiometer design visual field changes with light source incidence angle, 2, normalization step curve, the curve of the light source incidence angle change that the radiometer power response of actual measurement is measured with solar tracking system, 3, the vertical line of the normalization step curve upper base point midway of actual measurement, 4, theoretical step curve axis of symmetry.

Specific implementation method

Below in conjunction with accompanying drawing, specific embodiment of the invention method is described in further details.

The present invention gives a kind of method measuring sun pointing direction and radiometer optical axis included angle in tracking mode measurement pattern of solar irradiance.Concrete steps are as follows:

Step one: according to calculation of design parameters radiometer full filed angle 2, radiometer visual field θ ₁, half intensity field angle 2 θ ₂visual field 2 θ is blocked with nothing ₃, according to the power response Changing Pattern of absolute radiometer to different visual field, describe the theoretical step curve that power response changes with incident angle.

As seen from Figure 1, radiometer visual field is determined jointly by field stop and key light door screen, according to visual field design parameter and diaphragm diameter D and main aperture of the diaphragm d and the two spacing L, calculates radiometer field angle, is respectively:

${\mathrm{\θ}}_1={\tan }^{-1}\left(\frac{D+d}{2L}\right)$

${\mathrm{\θ}}_2={\tan }^{-1}\left(\frac{D}{2L}\right)$

${\mathrm{\θ}}_3={\tan }^{-1}\left(\frac{D-d}{2L}\right)$

Then 2 θ ₁for radiometer full filed angle, namely solar facula has just started to enter reception cavity when this angle is incident;

2 θ ₂for half intensity field angle, namely solar facula is blocked when this angle is incident half;

2 θ ₃for nothing blocks field angle, namely solar facula incidence within this angle all can enter into reception cavity.After calculating radiometer 3 field angle, power is P ₀light source incide absolute radiometer in above three kinds of different angles, it is trapezoidal that radiometer power response can be expressed as shown in Fig. 2 with the rule that light angle θ changes.

As shown in Figure 3, the radiometer visual field design parameter for concrete: d=8mm, D=13.3mm, L=100mm, the visual field calculating radiometer is: θ ₁=6.08 °, θ ₂=3.80 °, θ ₃=1.52 °, when the light source incidence of specific power, rule as shown in Figure 2 can obtain the normalized theoretical step curve 1 that radiometer power response changes with light angle, and in order to Fig. 3 is shown in clear expression, abscissa zone selects-3.5 ° ~ 4 °.Because radiometer visual field is axisymmetric, axis of symmetry is optical axis, so theoretical step curve 1 is be that the straight line of 0 ° is as axis of symmetry 4 using angle.

Step 2: radiometer is installed in sun pointing system, simulated solar light source is utilized to irradiate, first by sun pointing system measurement light source incident angle θ, then by the radiometer power response value under this angle of radiometer measurement, continuously change light source incidence angle θ, make it at-θ ₁~ θ ₁within change, measuring radiation meter is in the power response value of Different Light incident angle, and the data of actual measurement, in Table l, provide according to actual measurement data the normalization step curve 2 that radiometer power response changes with light source incidence angle, as shown in Figure 3.

The data that the radiometer power response of table 1 actual measurement changes with light source incidence angle:

Light source incidence angle	Normalized radiometer power response
		3.30	0.64526
3.13	0.69225
		2.95	0.74744
2.70	0.80334
		2.52	0.85255
2.33	0.90174
		2.11	0.95948
1.93	0.98364
		1.71	0.99167
1.49	1.00383
		1.31	1.00356
1.09	0.9997
		0.91	1.01711
0.70	0.99995
		0.51	1.01489
0.23	0.99957
		0.12	0.9961
-0.12	0.99648
		-0.31	0.99527
-0.51	1.00201
		-0.71	0.98073
-0.89	0.99338
		-1.09	1.00576
-1.32	0.99325
		-1.49	0.94528
-1.71	0.91532
		-1.91	0.87017
-2.09	0.79629
		-2.30	0.75204
-2.51	0.69042
		-2.70	0.61755

Step 3, determine the angle of vertical line 3 correspondence of the normalization step curve 2 upper base point midway of actual measurement, for the actual measurement data in table 1, judge that two end points of normalization step curve 2 upper base are respectively 1.71 ° and-1.32 °, its mid point is corresponding angle is (1.71 °+(-1.32 °))/2=0.195 °, this angle 0.195 ° and the absolute value of the difference of theoretical step curve 2 axis of symmetry 4 corresponding angle 0 °, be sun pointing direction and radiometer optical axis included angle 0.195 °.

Claims (3)

1. measure the method for sun pointing direction and radiometer optical axis included angle, comprise the following steps:

Step one: according to calculation of design parameters radiometer full filed angle 2, radiometer visual field θ ₁, half intensity field angle 2 θ ₂visual field 2 θ is blocked with nothing ₃, according to the power response Changing Pattern of radiometer to different visual field, describe the theoretical step curve (1) that power response changes with incident angle;

It is characterized in that, step 2: radiometer is installed in sun pointing system, simulated solar light source is utilized to irradiate, first by sun pointing system measurement light source incident angle θ, then by the radiometer power response value of radiometer measurement under this angle, continuously change light source incidence angle θ, make it at-θ ₁~ θ ₁within change, measuring radiation meter, in the power response value of Different Light incident angle, draws the normalization step curve (2) that the radiometer power response of actual measurement changes with incident angle;

Step 3: the difference determining the angle that the vertical line (3) of normalization step curve (2) the upper base point midway of actual measurement is corresponding and theoretical step curve (1) axis of symmetry (4) corresponding angle, this difference is sun pointing direction and radiometer optical axis included angle.

2. the method for measurement sun pointing direction according to claim 1 and radiometer optical axis included angle, it is characterized in that, the method calculating radiometer visual field described in step one is, according to field stop diameter D, main aperture of the diaphragm d and distance L therebetween, calculating radiometer visual field is:

${\mathrm{\θ}}_1={\tan }^{-1}\left(\frac{D+d}{2L}\right)$

${\mathrm{\θ}}_2={\tan }^{-1}\left(\frac{D}{2L}\right)$

${\mathrm{\θ}}_3={\tan }^{-1}\left(\frac{D-d}{2L}\right)$

Then 2 θ ₁for radiometer full filed; 2 θ ₂for half intensity visual field; 2 θ ₃for nothing blocks visual field.

3. the method for measurement sun pointing direction according to claim 1 and radiometer optical axis included angle, is characterized in that, θ=0 °, light source incidence angle that theoretical step curve (1) axis of symmetry (4) is corresponding.