Image-Based Heliostat Tracking for Decentralized Mirror Alignment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing heliostat tracking systems in solar thermal power plants face challenges with precision, efficiency, and cost-effectiveness due to insufficient initial installation accuracy, long calibration times, incomplete characterization of heliostat pose, and dependence on centralized control, especially in densely populated arrays with large 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 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 heliostat alignment can be measured, but calibration time becomes excessively long due to serial calibration of individual heliostats
Solution Approach 1:
The patent divides the calibration system into multiple independent imaging stations positioned at different locations around the receiver. Each station can independently image and calibrate heliostats simultaneously, transforming a serial calibration process into a parallel one. This segmentation of the calibration function across multiple spatial locations eliminates the time bottleneck of serial calibration while maintaining measurement precision.
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 solar flux
Solution Approach 1:
The patent extracts the imaging function from the immediate vicinity of the receiver aperture and relocates cameras to positions further away from the concentrated solar flux zone. By positioning cameras at a distance while maintaining line-of-sight to the heliostats, the system achieves parallel calibration capability without exposing the cameras to damaging concentrated sunlight, thus separating the calibration function from the harmful thermal environment.
3Reliability
If cameras are positioned far from the receiver to avoid flux damage, then camera safety improves, but the field of view and resolution required to image all heliostats becomes impractically large
Solution Approach 1:
The patent segments the field of view requirement by distributing multiple imaging stations around the receiver, each covering a specific angular sector. Instead of requiring a single camera to capture the entire heliostat field with extremely high resolution, multiple cameras at moderate distances each image a portion of the field. This segmentation reduces the resolution and field of view requirements for each individual camera while maintaining comprehensive coverage through the collective capability of the distributed imaging network.
4Ease of operation
If centralized control is used to coordinate multiple heliostats, then system coordination is achieved, but the system becomes dependent on central connectivity and less robust to environmental changes
Solution Approach 1:
The patent implements self-service by equipping each heliostat with an integrated imager and control system that enables autonomous calibration and tracking. Each heliostat independently determines its own alignment requirements and adjusts its mirror orientation without requiring continuous communication with a central controller. This decentralized architecture eliminates dependency on central connectivity, reduces system complexity, and enhances robustness to environmental changes while maintaining coordinated operation of the entire heliostat field.
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, efficient, and cost-effective tracking of the sun by each heliostat, improving precision and reducing the need for centralized control, while allowing for parallel calibration of multiple heliostats and robust operation against environmental changes.
Implementation Method 1
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.