Backstepping-based nonlinear adaptive control for boiler-turbine units

Adaptive nonlinear backstepping controllers for a typical nonlinear boiler-turbine unit model with several uncertain parameters are presented in this paper. The first step consists in system model processing, which involves adding integral actions to the basic backstepping algorithm to obtain zero static errors. Then, to follow the premise of backstepping, the system is divided into two sub-systems and the controllers are designed separately. During the design process, some virtual variables are introduced to define Control Lyapunov Functions (CLF) based on adaptive backstepping, then the nonlinear control laws of the system and adaptive updating laws of these uncertain parameters are deduced. At last, three simulation tests on a 500 MW boiler- turbine units in different operating conditions are done to prove the dynamic performance, disturbance rejection, and robustness of this system.