39. Modal Analysis of a Heliostat for Concentrating Solar Power

A heliostat is a structure whose function is to reflect sunlight to a target collector. Heliostat vibrations can degrade optical pointing accuracy and fatigue the structural components. This paper reports on an experimental and analytical program with a goal to improve understanding of the response to wind loading on heliostats. A modal test was performed on a heliostat located at the National Solar Thermal Testing Facility (NSTTF) at Sandia Labs in Albuquerque, New Mexico. Modal tests were performed with artificial and natural wind excitation. Strain and displacements were also measured under wind loading. The information gained from these tests has been used to evaluate and improve structural models that predict the deformations of the heliostat due to gravitational and dynamic wind loadings. The paper will provide an up-to-date summary of model validation work, evaluation of suitable sensors, and development of data-processing methods for long-term deformation monitoring.