Changing product specifications and load changes require that operating points have to be changed frequently during the operation of many processes. The nonlinear model predictive control (NMPC) schemes available at present that guarantee stability of the closed loop are, however, only suited to stabilize the behavior around one priori known steady state. The possibility for setpoint changes is not considered in the setup for these NMPC schemes and if this is incorporated in an ad hoc manner, stability cannot be guaranteed for varying setpoints. In this paper a new approach based on the well-known pseudolinearization in connection with the quasi-infinite horizon NMPC scheme is presented, that allows the stabilization not only around one setpoint, but rather of a whole family of setpoints. The pseudolinearization is used to obtain a closed expression for the controller parameters as a function of the setpoints, such that for every setpoint stability of the closed loop is guaranteed. The method is applied in simulation to the control of a chemical reactor.
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