Control of a Nonlinear Boiler-Turbine Unit Using Two Methods: Gain Scheduling and Feedback Linearization

Abstract

To achieve a good performance of a boiler-turbine unit, dynamic variables such as steam pressure, water level of drum and electric output of turbine must be controlled. In this paper a nonlinear model of the boiler-turbine unit is considered in which the inputs are the valve positions of fuel flow, steam control, and feed-water flow. Using two control methods, feedback linearization and gain scheduling, a PI controller is designed. It is shown that by applying both methods, system goes from one operating point to another with an appropriate specification of time response. Results show that system with a controller designed based on gain scheduling method has a better time response from a nominal operating point to a far operating point. In addition, applying any of these control approaches guarantees robustness of the system against the uncertainties associated with dynamic model.