Robust control of drum boiler

In this paper, we focus on robust decentralized controller design for Benchmark PID problem: nonlinear drum boiler, presented recently by Morilla [4]. For the control systems, used in practice, the most accurate mathematical model is needed, which includes the important features of the real system, and yet make it as simple as possible. When designing robust controllers, it is necessary to identify the system in several working points and determine the system model including uncertainties. In this paper we also deal with the identification of nonlinear model of the boiler, which has 3 inputs and 3 outputs. In our case, we chose one of the inputs as a constant with two variable values for working points, so we have our model reduced to 2×2. For identification we used three operating points, which we have chosen from the linear part from input output characteristics. After obtaining the transfer functions and respective uncertain model, various robust decentralized controller design methods are compared. The obtained results are verified on nonlinear model (based on real data).