This paper presents and demonstrates, by numerical simulation, a mixed-integer linear programming (MILP)-based Model Predictive Control (MPC) strategy for space-heating demand in buildings connected to a district heating system. The proposed MPC deals with space-heating demand with extended flexibility. It exploits thermal inertia, inherently present in the building and its heating system, to optimally plan space-heating load in anticipation of weather conditions and energy cost variations. MPC is based on a reliable Reduced-Order Model (ROM). Heating circuit and internal mass are carefully modelled within the ROM structure since these elements can be used for short-term heat storage and therefore play an important role in demand-side management. As for the model parameters identification, training data is restricted to non-intrusive, easily accessible measurements available at the substation level. The model identification approach and control strategy are applied to a well-insulated radiator-heated case-study building simulator developed in Modelica. Results show that the proposed ROM is reliable enough for an MPC application. Compared to conventional weather-compensation control, flexible MILP-based MPC proved to be cost-efficient, while preserving a decent indoor thermal comfort level.

Concentrating Solar Power (CSP) plants generate renewable electricity using the conversion of solar direct normal irradiation into thermal energy, then into mechanical work and electricity through the use of a thermodynamic cycle. Among the several available technologies, Direct Steam Generation (DSG), in which steam is generated directly in the absorber tubes of the solar field, and then directly fed to the turbine or thermal storage, holds interesting advantages. However, the steam generation system shows a difficult dynamic behavior which constitutes a challenge for the control system design. It is mainly due to the conjunction of the natural transient condition of solar irradiation and the presence of two phase flow in the absorber tubes. This paper reviews the control methods of the DSG systems used in linefocus CSP. The control systems are either proposed in literature, or actually applied in currently running plants or prototypes, although an extensive description is difficult to obtain in the case of the latter. The control systems are classified according to which DSG operation mode they refer to.