Nonlinear optimal-variable-aim strategy for improving multimachine power system transient stability

The paper presents an integrated excitation and fast valving controller for improving multimachine power system transient stability. The controller is based on an improved optimal-variable-aim strategy. To avoid transferring measurement information around the system, an `observation decoupled´ state-space model for multimachine power systems, which include a fast valve and an excitation system, is adopted. Simulation studies employed to test the controller have been performed on a four-machine six-bus system. The results show that the controller is effective for transient stability enhancement