Cross-Timescale Dynamics Interaction Analysis of DFIG-WTs-Dominated Power Systems Considering Nonlinear Effects

With the increasing penetration of wind power represented by Doubly Fed Induction Generator (DFIG) based wind turbines (WTs), the power system dynamics exhibit characteristics of multi-timescale. Moreover, the strong nonlinear characteristics of the system lead to cross-timescale coupled phenomena between multi-timescale dynamics in dynamic processes. However, previous studies typically employ linear methods to evaluate the stability of the equilibrium point neighborhood while ignoring the characteristics of cross-timescale caused by nonlinear effects. This paper addresses this gap by employing the normal form method (NFM) based on second-order Taylor expansions in the DFIG-WTs-dominated power systems. Subsequently, cross-timescale coupled modes and phenomena have been revealed. Furthermore, the frequency characteristics and damping characteristics of the coupled dynamics are analyzed. Finally, both cross-timescale phenomena are discovered and validated in real-time LAB(RT-LAB).