The region 1 is when the wind speed is under the cut-in wind speed v min. No maximization of effi ciency occurs on this region. Region 2 is when the wind speed is above v min but under the rated value v N. In this region, the main controller task is to increase the ef fi ciency of the W TS, operating it at its maximum power point (MPP). This is the main operational region.Region 3 is when the wind speed is abovev N but under the cut-out wind speed v max.In this region, the controller task is to keep the captured power at a fixed or rated value, instead of try to maximize it. Another important controller task in this region, is to keep the electrical and structural conditions in a safety region. This is done by varying the blade pitch. When the wind speed is above v max, VST shut-down in order to preserve the system integrity.The work presented here, treats the increase of ef fi ciency in region 2 by operating WTS at its MPP dall the analysis in this paper is done considering the angle of the blade pitch settled to zerod.However, it is not an easy task , because the dynamics of the system have strong nonlinearities, and the wide range operation of the system make that linear techniques are not well suited for this problem.