Improvement of Image Processing Control Accuracy for Cross Linear Heliostat. (May 2015)

• Record Type: Journal Article
• Authors: Aiba, T.; Tamaura, Y.; Tsuzuki, N.; Kikura, H.
• Is Part Of: Energy procedia. Volume 69(2015)
• Page Start: 1859
• Page End: 1867
• Publication Date: 2015-05
• Subjects: cross linear -- heliostat -- mirror control -- image processing.; Power resources -- Congresses; Power resources -- Periodicals; Power resources; Conference proceedings; Periodicals; 333.7905
• DOI: 10.1016/j.egypro.2015.03.164
• Languages: English
• ISSNs: 1876-6102

Abstract

Abstract: The existing solar concentration systems have a problems of lower concentration efficiency in winter season and at high latitude. Cross Linear concentration system (CL) has been newly invented to solve this problem. Mirrors are controlled with dual axes (rotation and elevation) for sun-tracking. This paper describes the preliminary investigation to clarify the pixel errors which can be applicable for the image processingheliostat control method in the CL system (CL-Image Processing/Heliostat controlling) (CL-IP/Hel-controlling). The CL-IP/Hel-controlling is achieved by adjustment of the different 3D positions of the mirror corners of the CL-heliostat between the calculated 3D position from the sun position and the image processing 3D position. The Cl-heliostat is controlled by the two axis of east/west (E/W) rotation axis and north/south (N/S) elevation axis, which we call "Gyro-type CL-heliostat", because its mirror weight is anytime balanced between E/W and N/Saxes at the gravity center of the mirror just like Gyro. For the Gyro-type CL-heliostat, the E/W rotationangle can be fairly exactly moved according to the sun rotation angle velocity in a day with a small adjustment of the N/S elevation angle in a day. So we can make a heliostat controlling with a longer interval between the heliostat controlling for sun tracking. Also, for the heliostat field area of CLsystem, the distance between the receiver and the mirror in each mirror line is 15-50m and the mirror number in each mirror line is 15. This seems to be within pixel errors which can be applicable for the image processing heliostat control. Edge detection method was applied for the detection of the mirror corner using the difference of RGB value. The intersection points of the two edge lines are detected as the mirror corner coordinates.From the image obtained from the receiver position using the Gyro-type CL-heliostathand-made in this study, the standard deviation of E/W rotation angle was about 0.3°, but that of N/S elevation angle, about 1°∼3°. The large error for the N/S elevation angle comes from the smaller movement of the corner point in the picture taken from the receiver side. From this result, considering the pixel errors arising from the camera position, it can be concluded that CL-IP/Hel-controlling is applicable for the CL-heliostat sun tracking system with an accuracy.