Large-scale utilization of wind energy has caused an increasing concern about its influence on the power quality of the power system. Variable speed wind turbine generators (WTG) with advanced power electronic converters inject harmonic currents in the network, which may potentially cause current and voltage distortions. In this paper a case study is presented to ascertain the distribution of harmonic currents and voltages in a wind farm consisting of 72 wind turbine generators. This analysis is then applied to the study of resonant conditions and harmonic filter design. © 2011 IEEE.