Wind turbine control methods for improving the production of energy

Method of operation of a variable speed wind turbine (11) having control means for its regulation tracking a power vs. generator speed curve (31) comprising a nominal zone (39) where the power is kept constant at a nominal value, a first sub-nominal zone (33) where the generator speed is kept constant at its coupling value, a second sub-nominal zone (35) where both generator speed and power are allowed to increase/decrease in line with wind speed and a third sub-nominal zone (37) between the second sub-nominal zone (35) and the nominal zone (39) that comprises a first vertical segment (41) at a generator speed nr2 higher than the generator nominal speed nr1 and a second vertical segment (43) at the generator nominal speed nr1 connecting with the nominal zone (39), each of both segments (41, 43) to be followed in function of the wind speed changes for optimizing the energy production.