A robust nonlinear multivariable controller for multimachine power systems

A new algorithm for the design of nonlinear robust voltage and speed regulator of large scaled multi-generators power systems is presented in this paper. The power system is modeled using a new decentralized modeling approach recently introduced by the authors. The approach consists of partitioning the power system into the generator to be controlled and the rest of the grid modeled as a time-varying impedance. The multi-input multi-output model obtained contains time-varying parameters representing the interactions among the generators. The new algorithm consists of first applying nonlinear linearizing and decoupling excitation and turbine gate input. The two subsystems obtained are stabilized by auxiliary controls derived from a backstepping procedure. The stabilizing controls can be split into two parts: a linear part for asymptotic stability, and a nonlinear part compensating by domination the interaction among generators considered as perturbations. Simulation on a four machines power system is performed to confirm the effectiveness of the controller.