Backstepping Design of Nonlinear Optimal Control

Exact linearization method can transform a nonlinear system into a linear system, on which traditional linear optimal control law is based. However in power systems only the performances of part of states are usually concerned by controller design. An optimal control designed for subsystem instead of the whole system is preferred. Backstepping procedure provides such a framework as to design partial optimal control for subsystem in a high-order system. This paper employs backstepping technique to design partial optimal control law for power systems with turbine dynamics. The proposed controller is applied in one-machine infinite-bus system as well as in multimachine system. The simulation results demonstrate that partial optimal control law is able to reduce the cost of control and improve the transient performance of generator rotor angle and speed