Modeling and Cross-Timescale Mechanism Analysis of Voltage Control Impact on Electromechanical Dynamics of VSG-Controlled DFIG-Based WT

With the development of doubly fed induction generator (DFIG)-based wind turbines (WTs), the application of virtual synchronous generation (VSG) concepts in DFIG control has gained attention for enhancing grid stability. The VSG-controlled DFIG system, characterized by its multiple timescale energy storage elements and control loops, presents a complex dynamic behavior of multiple timescales and there are interactions between different timescales. However, existing research mostly focuses on modeling and stability analysis of a single timescale, neglecting the cross-timescale effects. This paper presents a dynamic modeling methodology for VSG-controlled DFIG-based WTs to analyze the cross-timescale impact of voltage control on electromechanical dynamics. Firstly, cross-timescale phenomena and laws of the impact are revealed. An excitation and response dynamical model of VSG-controlled DFIG is proposed, which can provide a physical comprehension of the formation mechanisms behind cross-timescale phenomena within DFIG. Additionally, the analysis of the impact of voltage control on electromechanical dynamics is performed using the damping torque. Finally, the analyses of cross-timescale mechanisms are validated through time-domain simulations.