Wind farm modelling for power quality

In this paper, the power quality impact of wind farms on the power system is investigated. A model is established for the wind farm Hagesholm (Denmark). This wind farm consists of six active stall controlled wind turbines from NEG-Micon with 2 MW rated power. The wind turbines are connected through two feeders to the 10kV busbar in a 50/10kV substation. The simulation model, implemented in the dedicated power system simulation tool DIgSILENT, is used in the first place to simulate the behaviour of the wind farm during normal operation of the wind farm. The model comprises a grid model, six almost identical wind turbine models, where electric, mechanic and aerodynamic aspects are included, and a model for the wind speed. The described model can be used for assessment of power quality, control strategies and behaviour in the event of grid faults. In this paper, the ability of the model to predict power quality is investigated. The simulations are used to compute power quality characteristics of a wind turbine, i.e. maximum power, reactive power consumption and flicker emission. The applied computation methods are reflecting the international power quality standards of wind turbine IEC 61400-21. The computed power quality characteristics are compared to measured power quality characteristics, determined by the same computation methods.