An automatic choosing control for nonlinear systems

In this paper an automatic choosing control method is proposed for nonlinear systems. Nonlinear terms of the system are linearized piecewise so as to be able to design the linear optimal controllers. These controllers are smoothly united into a single nonlinear feedback controller by automatic choosing functions with unbiased characteristics. The resulting controller is a compact form which enables easy implementation and evaluates a stable region in the sense of Lyapunov by a Lyapunov function presented here. This controller is applied to a field excitation control problem of power systems. Simulation results show that the new controller improves the transient stability remarkably well