H∝ robust decentralized controller for nonlinear power systems

A methodology to design decentralized controllers for interconnected subsystems of nonlinear power system is suggested. It is based on exact linearization which is obtained using exact feedback linearization control (FBLC) and observation decoupled state space (ODSS) modeling. A nonlinear control law transforms the nonlinear system into an equivalent linear system. The decentralized nonlinear control law achieved is implemented through local measurements for each machine. The local controllers are designed simultaneously to avoid iterative process. H-infinity-robust control method is applied to obtain the robustness of the designed controller. For each subsystem, a decoupled, nonlinear control law is sought so that the overall closed loop system is stable and achieves desired H-infinity performance. Analysis is illustrated with a 3rd order model for two synchronous generators connected through a tie line. The methodology can be applied to almost all dynamical systems for which local measurements are available for feedback.