Site evaluation of harmonics distortions from modern wind turbines based on voltage source and harmonic impedances models

The modern wind turbines (WT), equipped with power converters (full or partial power converters) connected to the grid, have increased rapidly in recent years. Harmonic assessment of the power quality is a necessary study for interconnection of future wind farm to the grid. Normally, the power quality assessment in wind farm is done considering the power converter as an ideal harmonic current source, then, the injected harmonic currents are considered constant in any grid. This approach is not always valid since it neglects any grid harmonic impedance impact as well as the converter reaction to background harmonic voltages. In this study it has been modelled the Alstom Haliade 150 6MW wind turbine converter as a harmonic voltage source, including its filter and transformer harmonic model; with the theoretical harmonic impedance model and the background harmonic voltages of Le Carnet Wind farm (France) . The predicted voltage and current harmonics have been compared with real data measurement. The accuracy of this evaluation is much closer to reality than considering converters as ideal current sources as usual.