A novel power curve monitoring method for wind turbines was developed to prevent a turbine failure in a wind farm. Compared with the existing methods, this algorithm automatically calculates the power curve limits for power curve monitoring, even when a considerable number of abnormal data are included in wind speed-output power data measured at a wind turbine. In addition, the proposed algorithm automatically generates an alarm message when the wind speed-power data measured at the wind turbine deviate from the power curve limits, particularly considering their degree of deviation from the power curve limits and the cases when the measured data hover between the Warning Zones and the Alarm Zones. We confirmed its effectiveness through its field tests.