MODELLING AND ANALYSIS OF MEDIUM-SIZE HYBRID CSP-CPV SYSTEMS DESIGNED FOR IMPROVING THE DISPATCHABILITY OF SOLAR POWER PLANTS

The research study of the present Ph.D. Thesis has been carried out in order to study the performance of medium-size hybrid CSP-CPV systems designed for improving the dispatchability of Solar Power Plants and to develop and optimize novel management strategies for this kind of plants. The research topic has been chosen also for seizing the opportunity of testing the research results on a real plant: in fact, following the market trend, together with research purposes, an innovative renewable power plant is being built in Sardinia (Italy), which hybridizes CSP and CPV technologies together with thermal and electrochemical storage concepts: the Ottana Solar Facility. A preliminary study has permitted the author to examine in depth some of the main still-uncertain aspects with regards to the only CSP section of the Ottana Solar Facility: thermal losses influence on the performance of the overall Concentrating Solar Power Plant has been studied in connection with the main plant sections (Solar Field, Thermal Energy Storage and Power Block) during the different operating phases of the plant and according to weather conditions and load requirements. A special focus on the Solar Field behaviour allowed the author to study in detail the thermo-fluid dynamic evolution of the Heat Transfer Fluid temperature along the Solar Field loops across the time, during the morning warm-ups, the evening shutdowns and the full-operation transients and to determine a regulation curve for the Solar Field control. A deep analysis on the effects of implementing a recirculation strategy in the Solar Field management has been conducted. Different management strategies have been proposed and studied, for the overall hybrid CSP-CPV system. The results of the present Thesis allow to increase the scientific knowledge of hybrid CSP-CPV systems and show the improvement of the power dispatchability that can be achieved with a suitable integration of Concentrating Solar Power and Concentrating Photovoltaic.