Simultaneous Pyranometer Calibration Using Reference Pyrheliometer
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Solution Overview
Problem
Current calibration methods for solar irradiance sensors, such as pyranometers and pyrheliometers, are time-consuming, costly, and disrupt normal operation, especially in solar energy power plants, due to the need for frequent disconnection and recalibration, which affects accuracy and data integrity.
Innovation Solution
A system that simultaneously calibrates multiple pyranometers measuring diffuse and global irradiance using a reference pyrheliometer, allowing for continuous operation and accounting for temperature and incidence angle dependencies, thereby reducing costs and time through directional weighted average calibration constants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional calibration methods are used for pyranometers, then calibration accuracy can be achieved, but the calibration process is time-consuming and requires disconnection of sensors from normal operation
Solution Approach 1:
The patent combines multiple pyranometers and a pyrheliometer into a single integrated calibration system where all sensors are simultaneously calibrated during normal operation. The pyranometers are positioned at different orientations (horizontal and tilted) and calibrated together with the pyrheliometer using a unified data processing approach, eliminating the need for sequential calibration and disconnection of individual sensors.
Solution Approach 2:
The calibration system operates continuously during normal measurement conditions without requiring sensor disconnection or interruption of solar radiation monitoring. The pyranometers and pyrheliometer remain installed and functional throughout the calibration process, allowing simultaneous data collection for both operational monitoring and calibration purposes.
2Measurement precision
If traditional calibration methods are used for pyranometers, then calibration can be performed, but it is costly and requires frequent disconnection and recalibration
Solution Approach 1:
The calibration system serves multiple functions simultaneously: it calibrates both horizontal and tilted pyranometers using a single pyrheliometer reference, performs calibration during normal operational conditions, and provides continuous monitoring data. This multi-functional approach eliminates the need for separate calibration procedures for different sensor orientations and reduces overall calibration costs.
Solution Approach 2:
The system uses the pyrheliometer as a self-contained reference standard that provides its own calibration signal without requiring external calibration equipment or procedures. The pyranometers are calibrated autonomously by comparing their readings against the pyrheliometer measurements under identical solar radiation conditions, eliminating the need for external calibration services.
3Measurement precision
If pyranometers are calibrated separately and sequentially, then individual calibration can be achieved, but it disrupts normal operation and affects data integrity
Solution Approach 1:
Multiple pyranometers are calibrated simultaneously in a unified calibration process rather than sequentially. The system processes data from all pyranometers and the pyrheliometer together using a single calibration algorithm, ensuring that all sensors are calibrated under identical environmental conditions and maintaining continuous operational data integrity.
Solution Approach 2:
The calibration system continuously collects and processes data from all sensors during normal operation, performing calibration calculations in real-time or near real-time. This preliminary continuous calibration ensures that calibration adjustments are made proactively before significant drift occurs, maintaining data integrity without interruption.
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
Enables fast, reliable, and cost-effective calibration of solar irradiance sensors without disrupting their operation, improving accuracy by considering temperature and incidence angle effects, and reducing the need for frequent recalibration.
Implementation Method 1
A pyrheliometer is constituted by a tube whose length and diameter define an opening angle (field-of-view) and at the bottom of which is the sensing element, known as thermopile.
Implementation Method 2
A pyranometer is constituted by a metal body with a thermopile installed in one side, in which said thermopile is enclosed by one or two special glass or quartz domes to protect it from the external weather agents and improve sensor accuracy.
Data Source
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AI summary
System for calibrate two or more pyranometers that measure solar radiation, comprising an electronic data processor configured for generating a mean calibration constant of the pyranometers, by carrying out the steps of: installing a reference pyrheliometer with known calibration constant RDIR placed proximal to the pyranometers to be calibrated; acquiring measurements of direct normal irradiance; recording the average values VDIR × CZA, VDIF(i) with i = 1, ..., NDIF and VGBL(j) with j = 1, ..., NGBL at a same and synchronized averaging rate; fit a linear function in the form Y = M × X + B to the data points defined by Xi,j,k = VDIF(i)k/VGBL(j)k and Yi,j,k = VDIR × CZAk/VGBL(j)k with k = 1,...,NREC; calculating a calibration constants of the i-th pyranometer measuring diffuse irradiance through RDIFi,j = - RDIR/M and of the j-th pyranometer measuring the global irradiance (1b) through RGBLj,i = RDIR/B; calculating a mean calibration constant for the i-th pyranometer measuring diffuse irradiance through FDIF‾i=1NGBL∑j=1NGBLRDIFi,j, and a mean calibration constant for the j-th pyranometer measuring global irradiance through NGBL‾j=1NDIF∑i=1NDIFRGBLj,i.