Centralized PID control by decoupling of a boiler-turbine unit

This paper deals with the control of a nonlinear boiler-turbine unit, which is a 3×3 multivariable process with great interactions, hard constraints and rate limits imposed on the actuators. A control by decoupling methodology is applied to design a multivariable PID controller for this unit. The PID controller is obtained as a result of approximating an ideal decoupler including integral action. Three additional proportional gains are tuned to improve the performance. Because of the input constraints, a conditioning anti wind-up strategy has been incorporated in the controller implementation in order to get a better response. A good decoupled response with zero tracking error is achieved in all simulations. The results have been compared with other controllers in literature, showing a similar or better response.