Aggregated Models of a Large Wind Farm Consisting of Variable Speed Wind Turbines for Power System Stability Studies

Abstract—The main purpose of this paper is to present aggregation methods of a large wind farm consisting of variable speed wind turbines. Doubly fed induction generator (DFIG) and full power converter wind turbine concepts are considered in this study. The investigation emphasizes on short-term voltage stability studies. Influences of unequal distribution of wind speed across the wind farm on the response accuracy of the aggregated models are investigated. Non-linearities due to maximum power tracking (MPT) characteristics of the wind turbines in the wind farm are also taken into account. The study concludes that a two-machine equivalent representation of a large wind farm is sufficient for short-term voltage stability investigations. This assumption remains valid even if power output discrepancies among the wind turbines are large.