This paper presents and analyzes the measured power-quality results of a commercial onshore wind farm of 30 MW connected to the power grid of Taiwan Power System. The twenty 1.5-MW wind doubly-fed induction generators (DFIGs) of the studied Kuan-Yuan onshore wind farm are connected to the 69-kV bus through two step-up main transformers of 69/22.8 kV, 25 MVA. The measured results were recorded from September 25th, 2014 to October 28th, 2014 for total 33 days. The recorded results include three-phase voltages, three-phase currents, active power, reactive power, apparent power, power factor, frequency, current harmonics, voltage flickers, and voltage variations. It can be observed from the measured results that the power quality of the studied Kuan-Yuan onshore wind farm during the measurement interval can meet the grid code of Taiwan Power Company except the voltage flickers.