Operational inductance of DFIG-based wind turbines for fault current analysis during LVRT

As doubly fed induction generator (DFIG) based wind turbines (WTs) have already become a significant power source in modern power systems, characterizing its fault current is one of the basic requirements for system analysis. However, due to various fault ride through strategies and flexible switching schemes, this research is of less progress under severe grid fault conditions. In this paper, the operational inductance of DFIG-based WT is proposed for extracting the influence of various ride through strategies on fault current characteristics. Furthermore, a uniform and simple analytical expression is developed under the switch of three typical ride through strategies. Based on the obtained analytical expression, the allocation of initial value, damping and frequency deviation of stator current are identified and described clearly. Finally, the analytical results are verified with the mathematic solution and the IGBT-detailed simulation of a commercial GE 1.5MW WT.