Modelagem e controle de uma planta de dessalinização por osmose reversa

Abstract

This dissertation presents the modeling, linearization and control of a reverse osmosis (OR) water desalination system. The system considered has two proportional valves for control of the feed water flows, the bypass valve of the system pressure and the outlet of concentrate in the membrane. The controlled outputs are the potable water flow and the inlet pressure in the membrane. The speed of the pumping system is considered constant. A nonlinear OR membrane model was used to obtain a model in the state space form representative of the desalination system. For controller design purposes, the model was linearized around an operating region. During the validation process of the linearization using ISE, IAE and ITAE performance indexes, it was detected that the linearized model presented a satisfactory performance when near the operating point considered. The strategy of polo allocation control via state feedback and inclusion of integral action was used for purposes of follow-up of references and rejection of disturbances in the output variables. With the control strategy implemented, validation tests were performed in both the linearized and non-linear model of the plant, and their performance was analyzed through the specifications of the parameters tr, ts, Mp, and peak value , and that through them, response speed and response efficiency was confirmed for the reference segment and disturbance rejection, in addition to the amplitude of the steady-state error signal being zero, so the outputs followed the desired references, even with the coupling between variables.