Improvement of power quality distortion in a grid caused by wind turbines

The variable power of a wind turbine (WT) is usually supplied to the grid. This results in a reduction of power quality. In WT with AC-DC-AC power electronic converters, inductive storage in the DC branch may smooth the power. The paper investigates, by simulation, the smoothing of power transmitted to the grid as a function of the inductive storage parameters; these are the inductance, the minimum and maximum current during operation and also the short range (1-10 sec) overloading capabilities. It is shown that an inductive storage system capable of storing energy equal to the nominal power times two seconds results in a considerable reduction of power variation. The same storage is also sufficient to keep the WT running during the period of clearance of a fault in the grid. This may be of importance for the dynamic behaviour of power systems with significant wind power penetration.