Subsystems Modeling

Planning and control of solar plants calls for dynamical models of their main parts. This requires modeling the following elements: the solar field (Chap. 4), the thermal storage system and the power conversion system (PCS). A prediction model of the solar radiation (Chap. 2), electrical tariffs and electrical demands are also needed for optimal operation planning. Important variables to be considered are the temperature of the inlet HTF (TinTur) and of the outlet HTF (ToutTur) of the power block, as well as the HTF flow (qT) going from the storage system to the PCS. Other variables with an economic profile in the objective function appear, such as operational cost Cop, or electrical selling price tariff e1, or net benefits, B.

Solar radiation, ambient temperature and electricity selling prices are considered as perturbations. Predictions of these variables are needed for control. The field flow, (q) and the flow toward PCS, qT are the manipulated variables. The outlet HTF temperature and generated power are the main variables to be controlled. The temperature of the hot HTF feeding the PCS can be predicted using a model of the storage tank. The overall hierarchical control scheme computes the temperature and power references Tref and Pref to maximize benefits while fulfilling the plant operating constraints [19]. The main prediction models are treated in what follows.