Impact of Mechanical Power Variation on Transient Stability of DFIG-based Wind Turbine

Abstract

The input mechanical power affects the transient stability by changing the transient energy of the power system. The mechanical power characteristics of doubly fed induction generator (DFIG)-based wind turbines (WTs) are more complex and the variation ranges are wider when compared with those of synchronous generators (SGs’) owing to the different energy conversion mechanisms, which leads the transient stability of DFIG-based WT more diverse. This paper systematically analyzes the impact of the mechanical power variation on the transient stability of DFIG-based WT. Firstly, the analytical model considering the mechanical power is presented. In comparison with SG, the characteristics of mechanical power of the DFIG-based WT are summed up. Then, based on the model, the transient stability of a single DFIG-based WT-connected system is theoretically analyzed. The instability mechanism and phenomena are found to be variable in different wind speeds. Finally, the impacts of the summarized factors of mechanical power on transient stability of DFIG-based WT are discussed, including the wind conditions, aerodynamics and pitch controls.