Simulation and control of solar thermal power plant.

Abstract

The demand for energy consumption continuously increases while the availability of fossil energy steadily decreased. Solar energy is one of the main renewable options for power generation. However, unlike other sources of energy that can be manipulated, solar radiation acts as a disturbance that is uncertain and changes seasonal and on a daily base. Hence, control of solar thermal power plants is a challenging task. In this research, dynamic simulations of parabolic trough concentrated solar thermal power plants were performed in both open-loop and closed-loop to investigate the dynamic behavior of the power plant. The process and model used in this paper were adapted from Powell and Edgar. In the open-loop simulation, effects of the flow rate of heat transfer fluid (HTF) to the outlet temperature of the collector and power generation under daily solar radiation were demonstrated. The results showed inherent nonlinearity in the power plant. In the closed-loop simulation, three control configurations including single-loop HTF temperature control, single-loop power control, and dual-loop control (where both HTF temperature and power were controlled) were proposed. PI and MPC controllers were designed for each control configuration. In a closed-loop simulation using PI controller, continuous- and discrete-time PI were implemented. Continuous-time PI was implemented to see the possibility for control of the power plant in the ideal case while discrete-time PI was implemented for the comparison with MPC which was discrete in nature and more realistic. The results showed that continuous-time PI could keep all controlled variables at the setpoint for all control configurations while discrete-time PI and MPC could keep controlled variables at the setpoint for only some cases.

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