Multivariable PID controller design for a benchmark boiler

A drum boiler is a multivariable nonlinear system with strong interactions and input constraints. In this paper, a robust control method with feed-forward compensation is applied to design a multivariable PID controller for a benchmark boiler control problem, where the boiler model is proposed in an IFAC Conference and can be used as a benchmark for various control methods. H_∞ loop-shaping approach is used to design an optimal controller, and a multivariable PID controller is obtained as a result of approximating the high-order controller. Due to the input constraints, a conditioning anti-windup strategy has been incorporated in the controller implementation. Experiment simulations show that the proposed design achieves better performance indexes than the reference controls.