A Study of Nonlinear Control Schemes for A Boiler-Turbine Unit

Abstract

Advanced control is crucial for safe and efficient operations of power plants, especially in the presence of fast and large load changes. This paper studies the load change control problem for a 160MW boiler-turbine unit. Two schemes are proposed to effectively control the boilerturbine unit that has various constraints on the system states, outputs, control input and control rate. By taking advantage of the nonlinearities of the boiler-turbine unit, we design a nonlinear state feedback controller. With a careful selection of the controller gains, the states and control inputs can be guaranteed to be within the required physical constraints. Practically, lower and upper bounds on the system outputs are also imposed to prevent the critical variables, such as drum water level, moving beyond the physical limits. To further incorporate the constraints on the system outputs as well as control-input rates into feedback design, we utilize the moving horizon control strategy. The simulations of two control methods demonstrate the well-controlled performances of the boiler-turbine unit under large and fast load changes.