Modeling and control of concentrating solar power systems: a discrete-time adaptive scheme for temperature control in molten salt solar collectors fields.

Many different solutions have been developed in the last few years to concentrate the solar radiation for generating electrical power. Among the existing thermo-electrical Concentrating Solar Power technologies, parabolic trough fields are the most mature and one of the most suited for the application to large-scale plants. In this framework, the use of molten salts as Heat Transfer Fluid can provide major improvements to the parabolic trough technology. On the other side, the development of advanced molten salts plants calls for the conception of simple but effective temperature control policies able to cope with hard constraints and with the uncertainties that typically affect solar trough fields, which are mainly related to the variability of thermal and optical parameters among the collector modules. For plants in which multiple temperature measurements are available for each string of collectors, as in the case of the molten-salt technology under examination, an adaptive control strategy is proposed, which is aimed at satisfying the strict control requirements posed by the considered class of solar plants. The devised strategy relies on the combined use of a discrete-time nonlinear modelbased controller with an on-line parameter adaptation mechanism. Simulation results show that the proposed control policy, together with a specific constraints-handling strategy, allows one to effectively control the plant in various operating scenarios.