Transient stability control: a multi-level hierarchical approach

A two-level hierarchical control structure for obtaining an optimal control strategy during the transient ensuing major disturbances in multimachine power systems is presented. This structure involves localized subsystem controllers communicating with a transient coordinating controller. The local controllers, making computations in parallel, control each subsystem according to the interconnection variables provided by the transient controller. These interconnection variables are updated to satisfy interaction feasibility by means of an iterative procedure. The control strategy maintains system stability, even when the severity of the disturbances is increased, due to the feedback or closed-loop control formulation inherent in the strategy. A nonlinear multimachine example is included to illustrate the technique