Transient Stability of Wind Turbine Adopting a Generic Model of DFIG and Singularity-Induced Instability of Generators/Units With Power–Electronic Interface

A generic model of grid-connected doubly-fed induction generator (DFIG)-type wind turbines represented by differential-algebraic equations (DAE) is proposed for short-term transient-stability analysis. From the view of analytical research, vital simplifications are made to the complex physical model of DFIGs, whereas characteristic dynamics are still preserved. When the connection between the wind turbine and grid is weak, transient voltage collapse caused by singularity-induced instability (SII) is observed and analyzed adopting the generic model. In addition, it is shown that collapse might also occur when state variables of the dynamical system get out of control when the connection between the wind turbine and grid is stiff, where fast drop of dc-bus voltage occurs. Critical indices for evaluating transient-stability performances of the DFIG are proposed and parameter sensitivity analysis is carried out. Physical meanings of SII in generators/units with power-electronic interface in vector-oriented control frame are generalized. Novel interaction between the grid and these nonconventional generators/units is highlighted.