Heliostat Tracking Controller Using Antipodal Sun-Receiver Imaging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing heliostat tracking systems in solar thermal power plants face challenges such as long calibration times, incomplete characterization of heliostat pose, dependence on centralized control, and vulnerability to environmental changes due to the need for precise alignment and centralized control, especially when dealing with large arrays of heliostats at significant distances from the receiver.
Innovation Solution
A decentralized system using a two-dimensional imager mounted on each heliostat to capture images of the sun and receiver, with a tracking controller that determines the angular positions and orients the mirror to maintain an antipodal relationship between the sun and receiver, allowing for independent tracking and reducing the need for central coordination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a white screen with external cameras is used for calibration, then alignment error can be measured, but calibration time becomes excessively long due to serial calibration of heliostats
Solution Approach 1:
The patent divides the calibration system into independent segments by placing an imager on each heliostat rather than using a single centralized white screen system. This allows parallel calibration of multiple heliostats simultaneously, eliminating the serial processing bottleneck and reducing total calibration time while maintaining measurement precision through local independent measurements at each heliostat location.
2Productivity
If multiple cameras are positioned close to the receiver aperture for parallel imaging, then calibration speed increases, but the cameras become vulnerable to damage from concentrated flux
Solution Approach 1:
Instead of placing cameras near the receiver aperture (the traditional approach), the patent inverts the configuration by placing imagers directly on each heliostat mirror. This reverses the spatial relationship, allowing parallel calibration of multiple heliostats at high speed while the imagers are positioned away from the dangerous concentrated flux zone at the receiver, thereby protecting the sensors from damage.
3Ease of operation
If centralized control is used to coordinate multiple heliostats, then system coordination is achieved, but the system becomes dependent on connectivity and vulnerable to environmental changes
Solution Approach 1:
The patent implements self-service by equipping each heliostat with its own imager and control system, enabling autonomous operation without dependence on centralized coordination. Each heliostat independently measures its own alignment and performs corrections, eliminating vulnerability to connectivity issues and environmental changes that could affect centralized control systems. This decentralized approach maintains system coordination through individual self-adjustment rather than centralized management.
4Measurement precision
If the imager optical axis is perfectly aligned with the mirror normal vector, then tracking accuracy is maximized, but manufacturing and installation precision requirements become excessively stringent
Solution Approach 1:
The patent applies parameter changes by introducing a calibration parameter (offset vector) that accounts for misalignment between the imager optical axis and mirror normal vector. Instead of requiring perfect alignment during manufacturing and installation, the system measures the actual offset and compensates for it through parameter adjustment in the control algorithm. This transforms a stringent manufacturing precision requirement into a measurable and compensable parameter, significantly easing fabrication and installation tolerances while maintaining tracking accuracy.
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
This approach enables accurate and efficient tracking of the sun by each heliostat, reducing calibration time, improving pose characterization, and enhancing robustness against environmental changes, while eliminating the need for centralized control, thus improving overall system efficiency and reliability.
Implementation Method 1
an imager connected to the reflector, the imager having an aperture (such as a pinhole or lens) and an imaging plane
Implementation Method 2
a reflector for reflecting the incident radiation
Data Source
AI summary
A system (100) for directing incident sun light to a receiver (150) based on an integral imager (116) is disclosed. The system includes an imager (116) mounted to a reflector (112); a tracking controller (226) coupled to the imager; and one or more actuators (114) connected to the reflector and tracking controller. The tracking controller (226) is configured to receive and process image data from the imager (116); determine angular positions of a radiation source and target relative to the mirror normal vector (N) based on the image data; and orient the reflector with the axis bisecting the angular positions of the sun and receiver (150). When the optical axis of the imager is precisely aligned with the vector normal to the reflector, the source and target will be detected as antipodal spots (320, 330) with respect to the center of the imager's field of view, which may be used to effectively track the sun or like object.