Wind turbine control method

A wind turbine control method of at least one wind turbine comprising a rotor, a generator, a frequency converter, a control unit and means for connecting each wind turbine to a wind farm grid, said method comprising the steps, for each wind turbine, of:

• calculation of a voltage error (ΔV) based on a local voltage set point (VREF) and a local measured voltage (VMED), and
• calculation of an initial set point of reactive power (QT) to be generated based on the voltage error (ΔV),
• wherein said method further comprises the following steps of:
• limitation of the initial set point of reactive power (QT) by applying limits (Q—MAX, Q—MIN) calculated on the basis of the local measured voltage (VMED), thus obtaining at least one final set point of reactive power (Q—REF);
• calculation of a maximum limit of active power (P—MAX) depending on the final set point of reactive power (Q—REF) and the apparent power available;
• and
• generating the local voltage set point (VREF) based on an error between a primary set point of reactive power (Qi) and the reactive power generated by the wind turbine (Qi—MED),
• wherein terminals of each wind turbine are connected to the wind farm grid through a transformer, and the local voltage set point (VREF) corresponds to a reference of the wind farm grid voltage (VBUS), the voltage error (ΔV) being calculated as the difference between the local voltage set point (VREF) and an estimated wind farm grid voltage (VBUS—EST), the estimated wind farm grid voltage (VBUS—EST) being calculated based on a transformer model and on voltage, current and power factor measurements at the terminals of the wind turbine.

A wind turbine control method of at least one wind turbine comprising a rotor, a generator, a frequency converter, a control unit and means for connecting each wind turbine to a wind farm grid, said method comprising the steps, for each wind turbine, of:

• calculation of a voltage error (ΔV) based on a local voltage set point (VREF) and a local measured voltage (VMED), and
• calculation of an initial set point of reactive power (QT) to be generated based on the voltage error (ΔV),
• wherein said method further comprises the following steps of:
• limitation of the initial set point of reactive power (QT) by applying limits (Q—MAX, Q—MIN) calculated on the basis of the local measured voltage (VMED), thus obtaining at least one final set point of reactive power (Q—REF);
• calculation of a maximum limit of active power (P—MAX) depending on the final set point of reactive power (Q—REF) and the apparent power available;
• and
• limiting the power extracted from the wind depending on a maximum limit of active power (P—MAX) that can be evacuated to the grid by correcting the blade angle in the basis of the maximum limit of active power (P—MAX) that can be evacuated to the grid and an indicative value of the available mechanical power (P—MEC).