Optimal Current Allocation Strategy of DFIG-based Wind Farm during LVRT

Abstract

An optimal current allocation strategy for doubly-fed induction generator (DFIG)-based wind farms during low voltage ride-through (LVRT) is proposed in this paper. According to the current constraint of converters, the active/reactive operating domain of the DFIG-based WTG generator (WTG) is depicted, which gives that the WTG has different support capacity with different operating points. It is meaningful to allocate the current with consideration of its operating points. For different voltage dips, the same margin and the maximum active current principle are used respectively to optimize the current allocation. A fault voltage support datasheet is formed and sent to the WTGs in advance. Once a fault occurs, WTGs can react quickly to support active and reactive current according to the datasheet. The proposed control strategy can take full advantage of the remaining capacity and maximize the active current support in slight and severe fault condition, respectively. It is validated by simulation with DIgSILENT PowerFactory. The results verify the effectiveness of the proposed control strategy.1