Transient Modeling and Stability Analysis of DFIG-based Wind Turbine with Demagnetization Control during Severe Grid Fault

During severe grid fault, doubly fed induction generator (DFIG)-based wind turbines (WTs) demand switching to transient controls (e.g., demagnetization control) to suppress fault current. However, the transient stability considering LVRT control under weak grid fault has not been explored. To fill the gap, this paper firstly established the transient model of DFIG- based WT during severe grid fault, taking demagnetization control into account. Based on it, the stability of DFIG-based WT is evaluated by the Lyapunov's energy function and inverse trajectory method. It discovered that improper demagnetization control could lead to new transient instability issue. Moreover, the implications of diverse elements (i.e., the grid condition, grid impedance, demagnetization coefficient, PLL control parameters) on the transient stability are revealed, and some control design guideline is provided for DFIG-based WT during severe grid fault. Eventually, the analysis is verified via experiments.