Flexible Nonlinear Control Technique with Applications to Power Systems

This paper presents the so called Direct Feedback Linearization (DFL) technique as a simple and flexible method for nonlinear control design. The DFL avoids the complexity of the well known differential geometric method, instead it uses Implicit Function Theorem (IFT) to eliminate system nonlinearities. This allows more flexibility in the exact linearization steps. To consider the effect of plant parametric uncertainties, robust control theory is used to ensure the stability of the DFL compensated system. As an example application, four different robust nonlinear excitation controllers are designed and compared to enhance transient stability of power systems. The main advantage of the proposed technique is the possibility for a control engineer to choose the most appropriate performance enhancing nonlinear compensating controller based on availability of measurements or required simplicity in the feedback loop design.