A device and a method of controlling blade instabilities of a wind turbine is provided. The method including the following steps: defining at least one preliminary overspeed threshold value; defining a fluttering rotor speed at and above which a predetermined fluttering of at least one of the blades occurs, the fluttering rotor speed is defined as a function of the pitch angle and/or as a function of the wind speed; setting a final overspeed threshold value to be equal to or smaller than a minimum rotor speed of the at least one preliminary overspeed threshold value and the fluttering rotor speed at the actual pitch angle and/or at the actual wind speed; and controlling the rotor speed to not exceed the final overspeed threshold value.

A rotation speed avoidance control method for a wind turbine generator system. The method comprises: when a power-limited operation instruction is received, determining a power value upper limit required by the instruction: determining whether the required power value upper limit is in a power avoidance interval corresponding to a rotation speed avoidance interval; and when the required power value upper limit is in the power avoidance interval, setting the maximum allowable power value of a wind turbine generator system to be a lower boundary value of the power avoidance interval. An upper boundary value of the power avoidance interval is a power value determined on the basis of an upper boundary value of the rotation speed avoidance interval, and the lower boundary value of the power avoidance interval is a power value determined on the basis of a lower boundary value of the rotation speed avoidance interval, wherein the rotation speed avoidance interval and the power avoidance interval are open intervals. By means of the control method, an operation range of the rotation speed of a wind turbine generator system in a power-limited operation state can be prevented from overlapping with a rotation speed avoidance interval, thereby preventing resonance of the generator system, load increase or other safety problems. In addition, the present invention further relates to an apparatus for implementing the control method, and a wind turbine generator system.

A wind turbine generator system and a rotation speed avoidance control method therefor. The method comprises: according to statistical information of the rotation speed of a generator being in a rotation speed avoidance interval, identifying whether a wind turbine generator system repeatedly falls within the rotation speed avoidance interval; and when it is determined that the wind turbine generator system repeatedly falls within the rotation speed avoidance interval, adjusting a rotation speed avoidance control parameter of the wind turbine generator system according to the statistical information of the rotation speed being in the rotation speed avoidance interval. Correspondingly, further provided is a rotation speed avoidance control apparatus for a wind turbine generator system.

A pitch control method and system of a symmetrical-airfoil vertical axis wind turbine collects data by an anemometer, an anemoscope and an angle sensor, outputs an optimum pitch angle based on a control law of a pitch angle and controls the pitch angle to be the optimum pitch angle through a pitch control actuator. In addition to input variables of the control law such as a wind velocity v.sub.in and a blade azimuth angle Ψ, constants such as a rotation radius R, a rotation velocity Ω of the blade and aerodynamic coefficients c.sub.1, c.sub.2 and c.sub.3 are also related. A Reynolds number has little influence on three aerodynamic coefficients c.sub.1, c.sub.2 and c.sub.3. The pitch actuator controls the adjustment rods to realize the automatic pitch control of the blades. An expression of the control law of the pitch is concise, the calculation time is short, and a response speed is fast.

Methods and Apparatuses for rotational speed avoidance control of a wind turbine, and the wind turbine are provided. An exemplary method includes: identifying whether a wind turbine operates repeatedly traversing a rotational speed avoidance range, based on statistical information about a rotational speed of a generator being in the rotational speed avoidance range; and adjusting a parameter of a pitch control system and/or a parameter of an electromagnetic torque control of the wind turbine based on the statistical information about the rotational speed being in the rotational speed avoidance range, in response to determining that the wind turbine operates repeatedly traversing the rotational speed avoidance range.

The invention relates to a method for controlling a wind turbine during start up, from a non-producing operation mode to a power producing operation mode when limit cycles occur during start-up. Limit cycles are detected when a number of cut-in transitions or a number of cut-out transitions are detected. A cut-in transition is when the wind turbine fails starting up despite having the wind speed or rotor speed normally required to enter a power producing operation mode. A cut-out transition is occurring when the wind turbine is falling out of power producing operation mode after having entered the power producing operation mode.

Method for controlling a rotor speed of a rotor of a wind turbine at rated or curtailed operation conditions the rotor being an aerodynamic rotor having one or a plurality of rotor blades, and the wind turbine further having a tower and a generator wherein a pitch control provides a pitch angle set value depending on an actual rotor speed for setting a pitch angle of the rotor blades, a main control provides a main power or torque set value for controlling the power or torque of the generator, and an additional control provides an additional power or torque set value depending on the actual rotor speed , wherein the additional power or torque set value is provided as an offset value and is added to the main power or torque set value respectively, wherein the additional power or torque set value is calculated depending on a control deviation of the rotor speed, and optionally, in combination with the additional control, or instead of it, a maximum power control provides a maximum power value as a varying value for limiting an output power of the generator and the maximum power value is calculated depending on a predetermined power limit value, and depending on a predetermined reference duration, in order to provide for the reference duration an average power reaching or at least not exceeding the predetermined power limit value.

A method for operating a wind turbine for generating electrical power from wind, wherein the wind turbine has an aerodynamic rotor with a rotor hub and rotor blades of which the blade angle is adjustable, and the aerodynamic rotor can be operated with a variable rotation speed, and the wind turbine has a generator, which is coupled to the aerodynamic rotor, for the purpose of generating a generator power, wherein the generator can be operated with a variable generator torque, comprising the steps of: determining a loading variable which indicates a loading on the wind turbine by the wind, and reducing the rotation speed and/or the generator power in a loading mode depending on the loading variable, wherein at least one force variable that acts on the wind turbine is used for determining the loading variable or as the loading variable.

A method of controlling a wind turbine for the avoidance of edgewise vibrations. The method comprises the steps of determining a whirling mode frequency of a rotor blade of the wind turbine; determining a rotational frequency of the rotor blade corresponding to the speed of the rotor blade; determining a threshold value for the whirling mode frequency based on the rotational frequency; and, reducing the speed of the rotor blade if the whirling mode frequency substantially equals or is less than the threshold value.

A system and method are provided for controlling a wind turbine of a wind farm. Accordingly, a controller implements a first model to determine a modeled performance parameter for the first wind turbine. The modeled performance parameter is based, at least in part, on an operation of a designated grouping of wind turbines of the plurality of wind turbines, which is exclusive of the first wind turbine. The controller then determines a performance parameter differential for the first wind turbine at multiple sampling intervals. The performance parameter differential is indicative of a difference between the modeled performance parameter and a monitored performance parameter for the first wind turbine. A second model is implemented to determine a predicted performance parameter of the first wind turbine at each of a plurality of setpoint combinations based, at least in part, on the performance parameter differential the first wind turbine. A setpoint combination is then selected based on the predicted performance parameter and an operating state of the first wind turbine is changed based on the setpoint combination.