Virtual model of a mirror orientation mechanism in solar energy applications, to evaluate its pointing accuracy in presence of external excitations

The paper presents the preliminary results of a study performed at the MGMVLab / S.Ilario Solar Station of the University of Genoa on the use of a virtual model to evalu¬ate dynamic phenomena and pointing accuracy perturbations induced by external exci¬tations (due e.g. to wind or traffic) on the mirrors orienting mechanism in solar energy power plants. This clearly involves the balance between the structural flexibility of the mechanism due to cost reduction exigencies and the accuracy required for a proper op¬eration. Obviously also the supporting structure influence must be considered; the pre¬sent paper refers mainly to the pointing linkage. The model analyzes a specific version of the Francia mechanism [1], the one adopted in the S.Ilario Solar Station of the Genoa University; it has been created using the Motion module of the LMS Virtual Lab software for multibody simulation. Due to the charac¬teristics of the system under examination, the “flexible body” module has been imple¬mented, making possible to consider as flexible some parts of the system in a multibody simulation, through an interface with a finite elements code. The parts to be modeled as flexible have been individuated through an experimental modal analysis performed on a single mirror mechanism; its results showed the ele¬ments which mostly participate to the modeshapes of the low frequency flexural modes considered as the mostly critical. The experimental results have been also used to vali¬date the FEM models of the elements modeled and inserted into the multibody software.