Estimation based Maximum Power Point Control of DFIG based Wind Turbine Systems

The majority of the control schemes of doubly fed induction generator (DFIG) wind turbine systems for the maximum power capture are dependent on its internal states or functions based on these states. Thus, the availability of these states is required to implement such a control scheme in practical. But sometimes some of the states are not available (measurable) to formulate the control law. Hence, this paper recommends the estimation of such unobservable states to implement the maximum extraction control of DFIG based wind energy conversion system in practice. It is based on the estimation based control of the DFIG for the active power control for MPPT as well as the control of the stator terminal voltage. The estimation of the unobservable states have been carried out by Unscented Kalman Filter (UKF), a discrete-time nonlinear estimator. The active power and stator voltage control has been implemented through the rotor flux control approach.