Observer-based nonlinear control of synchronous generators with perturbation estimation

This paper presents a new observer-based nonlinear controller (ONC) for excitation control of synchronous generators. The observer-based nonlinear control is basically an input/output feedback linearizing control of nonlinear systems but it employs output feedback and perturbation estimation. A sliding mode observer is used to estimate system states and a fictitious state which is introduced to represent the combinatorial effect of system uncertainties and nonlinearities. The successful estimation of states and perturbation allows the input/output linearization of the nonlinear system without requiring the accurate model. This constitutes a real-time compensation mechanism against the perturbations. The new ONC has main advantages of simple structure and robust performance. Simulations studies based on a singlemachine quasi-infinite bus power system are undertaken to evaluate the proposed approach. The simulation results show that the ONC can provide superior performance in comparison with that obtained using the conventional model based state feedback linearizing controller.