An evaluation system and performance monitoring of a wind turbine.

An evaluation system and performance monitoring of a wind turbine. A system for evaluating performance of a wind turbine (3), the steering system includes measuring means (11, 15) of a meteorological parameters M1, M2 respectively located in the wind turbine (3) and a meteorological mast (5) and measuring means (13) of orientation and of the power produced Pr comprising a computerized unit (21) connected to said measuring means (11, 13, 15) with a first calculation module (23) that obtains a power feature Pc as a function of these parameters from data obtained during a first stage of operation and a second calculation module (25) obtaining the average deviation existing Dm between power Pr actually produced and the characteristic power Pc by function obtained with the first calculating module (23) in the set of one or more data sets.