Analysis and Assessment of Stator Flux Attenuation Time-Scales of Type-3 Wind Turbines with Different LVRT Control Modes

The grid codes have strict rules for reactive power response time of wind turbines (WTs) during low voltage ride through (LVRT). For the type-3 WT, the response time is mainly depended on the attenuation rate of transient stator flux, which is closely related to the rotor-side control modes (i.e., LVRT solutions). Unfortunately, the characteristic of stator flux attenuation time-scale is hardly considered in the existing work on transient behavior analysis. For this issue, this paper firstly calculates the attenuation time constant of the stator flux under various LVRT control modes. Then, their flux attenuation time-scales are analyzed and compared using a typical MW-level WT. The analysis helps to assess the feasibility for satisfying LVRT requirement of reactive response time, besides that it contributes to the optimization of the reactive compensation configuration in wind farms. The analysis is validated by the simulation on a 1.5-MW WT.