Modelling, analysis and control of a wind-turbine driven self-excited induction generator

A wind-turbine driven self-excited induction generator is considered as a variable speed, constant voltage, constant frequency supply for isolated resistive loads. First, a general nonlinear model of the system is developed in a synchronously rotating reference frame. Next, using a modified approach of the singular perturbation theory, an order reduction is carried out by neglecting the fast transients existing in the system and a simplified model is obtained. Then, based on the reduced order model, the steady-state operating characteristics and the stability performance of the system are derived. Finally, the simplified model is used to develop a control strategy which aims to maintain the generator terminal voltage and frequency constant in case of variations in the load and/or windspeed.