Heliostat Reflector Calibration Using Frequency-Coded Motion
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Solution Overview
Problem
Existing calibration methods for reflectors concentrating solar radiation are susceptible to errors due to brightness differences, leading to inaccurate positioning and reduced efficiency in concentrating sunlight on a radiation receiver.
Innovation Solution
A calibration method and apparatus that utilize a camera to record picture element series with time-offset frames, transforming them into frequency space to determine reflector target positions, allowing for precise analysis and alignment of reflectors with distinct movement patterns, thereby minimizing errors and increasing calibration efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If camera images are used to record brightness differences for heliostat alignment, then the alignment process can be performed, but the brightness differences cannot be ascertained accurately leading to calibration errors
Solution Approach 1:
The patent applies mechanical vibration by causing each heliostat to perform a specific movement pattern (oscillation) that modulates the reflected light. This vibration-based approach transforms the static brightness measurement problem into a dynamic signal that can be distinguished through frequency analysis, thereby achieving accurate measurement despite using simple camera imaging.
Solution Approach 2:
The patent implements periodic action by assigning each heliostat a periodic movement pattern at a specific frequency. The camera records the periodic modulation of reflected light, and through frequency analysis, the system can accurately determine individual heliostat positions and brightness differences, resolving the measurement precision issue.
2Productivity
If multiple reflectors are calibrated simultaneously, then calibration efficiency increases, but the complexity of managing distinct movement patterns and data analysis increases
Solution Approach 1:
The patent applies segmentation by assigning each reflector a unique movement pattern parameter (different frequency, amplitude, or phase). This segmentations the collective calibration process into individually distinguishable signals, allowing simultaneous calibration of multiple reflectors while maintaining the ability to analyze each one's contribution separately through frequency-domain analysis.
Solution Approach 2:
The patent uses partial action by having each reflector perform only a specific portion of the overall calibration task through its unique movement pattern. The excessive action refers to the camera recording all movements simultaneously with higher temporal resolution than any single reflector needs, enabling post-processing separation of individual contributions through spectral analysis.
3Productivity
If calibration is performed during operation at high radiation intensities, then system availability is maintained, but the risk of measurement errors and energy loss increases
Solution Approach 1:
By using mechanical vibration of reflectors during operation, the patent creates a dynamic calibration signal that stands out against the static high-radiation background. The vibration-induced modulation allows accurate measurement even during normal operation, maintaining system availability while ensuring measurement reliability through the distinctive temporal signature of the vibrating reflectors.
Solution Approach 2:
The patent enables continuous calibration during operational periods rather than requiring shutdowns. The useful action of calibration continues uninterrupted alongside power generation, with the vibrating reflectors providing continuous calibration signals that can be extracted from the ongoing operational data stream, maintaining both productivity and reliability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method achieves high accuracy in determining reflector target positions, enabling precise calibration of multiple reflectors simultaneously and allowing for calibration during operation without significant energy loss, even at high radiation intensities.
Implementation Method 1
the reflectors are aligned in order to at least partly impinge a calibration surface with solar radiation reflected by the reflectors
Implementation Method 2
a spectrum is ascertained for each picture element series by a transformation of the picture element series into frequency space
Data Source
AI summary
The invention relates to a calibration method for a group of reflectors for concentrating solar radiation onto a radiation receiver, having the following steps: A) aligning the reflectors in order to at least partly expose a calibration surface to solar radiation reflected by the reflectors; B) modifying the intensity distribution of the radiation incident on the calibration surface by carrying out a pattern of movements by each reflector of the group, wherein at least one specified parameter for the pattern of movements of each reflector differs from the parameters of the other reflectors, said parameter being selected from the group: —movement frequency,—movement amplitude,—movement phase angle, and—trajectory of the solar radiation, reflected by the reflector, within the calibration surface; C) recording rows of pixels for a plurality of differently located location points of the calibration surface by at least one camera, each row of pixel having at least five temporally offset pixel recordings; D) ascertaining a spectrum for each row of pixels by transforming the row of pixels into the frequency domain; E) assigning a subset of spectra to the reflectors on the basis of the movement pattern parameter of the reflector; and F) determining at least one reflection target position for each reflector at least on the basis of the subset of spectra assigned to the reflector. The invention additionally relates to a calibration device for a group of reflectors for concentrating solar radiation onto a radiation receiver.