A New Non-Smooth Simplified Model for DFIG in Electromechanical Transient Analysis

The transient of the DFIG engages a lot of non-smooth elements such as switches of controllers and saturation of limiters, thus, the simplified non-smooth model of DFIG for electromechanical transient analysis is needed. This paper proposes a non-smooth simplified model of DFIG for electromechanical transient analysis, with the viewpoint of the transient response and energy accumulation. First, the general non-smooth dynamic behavior of DFIG during fault-on and post-fault periods are presented and the model is divided into four smooth stages. Then, the detailed model for the transient stage, according to without/with the trigger of the crowbar is presented. Furthermore, the simplified model of DFIG in the steady state is introduced according to without/with the trigger of the crowbar and saturation of limiters, determined by the stator voltage. Moreover, the transient model with/without the crowbar protection are simplified according to the principle of constant energy accumulation. Thus, the overall non-smooth simplified models of DFIG is obtained. Finally, the effectiveness of the proposed non-smooth simplified model is verified with the simulations.