Nonlinear Predictive Control for Temperature Regulation of Solar Furnaces

Abstract

In the context of material synthesis and thermal stress tests, solar furnaces play a fundamental role. These experimental systems are usually operated manually by trained operators. However, the use of automatic controllers can be essential to take into account the different dynamics of the treated materials, follow the different temperature profiles required in the tests, meet system security requirements, and face the intermittency of the main energy source, the solar energy. On these bases, the present work proposes a control system for temperature regulation in solar furnaces. The controller is based on a nonlinear model predictive control strategy that deals, in a single control layer, with the nonlinear behaviour of the system, the effect of disturbances, and the system's operating constraints. The controller was experimentally tested in the solar furnace SF60 of Plataforma Solar de Almería (southeast Spain), showing adequate performance against setpoint temperature changes, reaching a settling time of the order of 54 % faster than the open-loop system's time constant, and effectively rejecting irradiance disturbances. In addition, the operational constraints were ensured in almost all operating circumstances, observing only slight deviations of less than 2°C. These results allow us to position the proposed controller as a relevant tool for daily operation.