Effect of the shafting nonorthogonal error on the tracking performance of solar dish concentrator system

Abstract

A solar dish concentrator (SDC) system accurately tracks the sun using a dual-axis tracking device to achieve efficient heat utilization. However, the tracking performance and optical performance of an SDC system are significantly reduced by shafting nonorthogonal errors between the elevation axis and azimuth axis of the double-axis tracking device and the focal axis of the parabolic dish concentrator occurring during installation. In this paper, a tracking performance model of an SDC system is established based on the rigid body motion theory; the model considers the nonorthogonal errors between the elevation axis, azimuth axis, and focal axis. The radial angle and tangential angle are used to describe the deviation error of each axis from its ideal position. A virtual motion model of the SDC system with the nonorthogonal errors is established in the Solidworks 2014 software to verify the accuracy of the mathematical model. The influences of the nonorthogonal errors (single-factor error and overall error) on the tracking accuracy and comprehensive tracking performance of the SDC system are analyzed in detail. The results show that the tracking errors (single-factor error and overall error) of the SDC system increase and the tracking performance decreases as the radial angle error increases. When the radial angle error is the same and the axis vector changes (ie, the size of the tangential angle), the tracking performance of the SDC system improves. The focal axis error has the largest influence on the tracking performance of the system, followed by the azimuth axis error and the elevation axis error. The tracking performance of the SDC system is better when the azimuth axis is biased toward the south and north than toward the east and west and for elevation axis errors in the horizontal plane than the vertical plane. This work can provide a theoretical basis for the installation, debugging, and error control of solar concentrating systems with a double-axis drive.