The data used in this work were archived values from onshore MW class WTGs, from wind farms located in Canada As suggested by Butler et al., the region of the power curve conserved was the region where wind speed was between cut-in speed and nominal speed (Zone II of the power curve) [14]. This was done, first of all, because values for wind speeds greater than nominal speed were rejected for monitoring purposes. In this region of the power curve the WTG's control system interferes with the operating conditions required to maintain the power at its nominal value. Secondly, Zone II of the power curve is where the most energy is produced. The first year of available archived data was used as the reference period, and it was assumed free of underperformances or other issues.