State Feedback Control Of Wind Energy Conversion System Involving Squirrel Cage Induction Generator

This paper presents a theoretical framework for a control strategy of wind energy conversion system (WECS), using a squirrel cage induction generator (SIG) connected with an AC/DC/AC converter based on an Insulated Gate Bipolar Transistor (IGBT) with a Pulse Width Modulation (PWM) control approach. The proposed strategy involves a multi-loop nonlinear controller designed to meet the two main control objectives i.e. (i) speed reference optimization, designed in order to extract a maximum wind energy whatever the wind speed, and (ii) power factor correction (PFC) requirement must be satisfactorily realized. First, is a nonlinear model of the whole controlled system is developed within the Park coordinates. Then, a multi-loop nonlinear controller is synthesized using the backstepping design technique. A formal analysis based on Lyapunov stability is carried out to exhibit the control system performances. In addition to closed-loop global asymptotic stability, it is proven that all control objectives (induction generator speed tracking, rotor flux regulation, DC link voltage regulation and unitary power factor) are asymptotically achieved.