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.

The present invention provides improved methods, apparatus, and manufacture for an Archimedes Screw using a new blade design to increase the volume of water raised or lowered by about 9%-18%. The invention, in part alters the shape of the blades within the screw from a helicoid shape to a new shape called a “makroid” by the inventor. A helicoid blade in an Archimedes Screw has been used since antiquity and has not changed since then, limiting the efficiency. The makroid shape allows a greater quantity of water to be contained within the screw.

A pitch control method and system of a symmetrical-airfoil vertical axis wind turbine is provided, which 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.

A method and a system for calibrating a wind vane of a wind turbine, a method for monitoring a wind turbine, and a method for operating a wind turbine are provided. The method comprises: measuring first and second wind speeds with anemometers and a wind direction with a wind vane, a multiplicity of measurement values being recorded over a defined time period; determining differences between the first and second wind speeds; determining a model function for a relationship between measured wind directions and determined differences, at least one first model function being determined for a first wind-speed bin and at least one second model function being determined for a second wind-speed bin; determining at least one intersection point value of the measured wind direction where the first model function and the second model function intersect; and outputting the intersection point value as an installation angle of the wind vane.

A sensor system for a wind turbine, comprising: a blade load sensor; a blade temperature sensor configured to provide a temperature measurement of an associated blade; a load calculation module configured to output a temperature-corrected blade load value; and a processing unit interfaced with the temperature sensor. The processing unit includes a temperature estimator configured to determine an estimated temperature of the wind turbine blade based on at least one wind turbine parameter; and a comparator configured to generate a fault signal based on a comparison between the blade temperature measurement and the estimated blade temperature. The invention also resides in a corresponding method.

A method and a system for calibrating a wind vane of a wind turbine, a method for monitoring a wind turbine, and a method for operating a wind turbine are provided. The method comprises: measuring a first wind speed by means of a first anemometer, a second wind speed by means of a second anemometer, and a wind direction by means of the wind vane, a multiplicity of measurement values being recorded over a defined time period; determining differences between the first wind speed and the second wind speed at least substantially at the same instants in each case; determining a model function for a relationship between measured wind directions and determined differences that correspond at least substantially to the same instants, at least one first model function being determined for a first wind-speed bin and at least one second model function (being determined for a second wind-speed bin; determining at least one intersection point value of the measured wind direction at which the first model function and the second model function intersect; and outputting the intersection point value as an installation angle of the wind vane.

The present invention relates to a control system for thrust-limiting of wind turbines, which wind turbine comprises at least one tower, which tower carries at least one nacelle which nacelle comprises a rotating shaft, which shaft is rotated by one or more blades, which blades at pitch regulated by a pitch control system. It is the object of the present invention to reduce mechanical load and stress of a wind turbine. A further object is to reduce the maximal load on tower of a wind turbine. The thrust-limiting control system performs control of the pitch angle, which thrust-limiting control system performs regulation of the pitch angle based on at least a first input from a wind estimator and a second input from a turbulence estimator. By thrust-limiting control, reduction in the maximum mechanical load on a tower, or maybe also a nacelle, can be achieved by a relatively high percentage of the load in a way where it has only very limited influence on the power production of the wind turbine.

A sensor system for a wind turbine, comprising: a blade load sensor; a blade temperature sensor configured to provide a temperature measurement of an associated blade; a load calculation module configured to output a temperature-corrected blade load value; and a processing unit interfaced with the temperature sensor. The processing unit includes a temperature estimator configured to determine an estimated temperature of the wind turbine blade based on at least one wind turbine parameter; and a comparator configured to generate a fault signal based on a comparison between the blade temperature measurement and the estimated blade temperature. The invention also resides in a corresponding method.

The present invention relates to a control system for thrust-limiting of wind turbines, which wind turbine comprises at least one tower, which tower carries at least one nacelle which nacelle comprises a rotating shaft, which shaft is rotated by one or more blades, which blades at pitch regulated by a pitch control system. It is the object of the present invention to reduce mechanical load and stress of a wind turbine. A further object is to reduce the maximal load on tower of a wind turbine. The thrust-limiting control system performs control of the pitch angle, which thrust-limiting control system performs regulation of the pitch angle based on at least a first input from a wind estimator and a second input from a turbulence estimator. By thrust-limiting control, reduction in the maximum mechanical load on a tower, or maybe also a nacelle, can be achieved by a relatively high percentage of the load in a way where it has only very limited influence on the power production of the wind turbine.

A method is for operating a wind turbine having a tower, a rotor with a rotor blade and a generator coupled to the rotor. The wind turbine further includes a pitch setting system for changing the pitch angle of the rotor blade and a generator controller for controlling the generator torque. The method includes providing first information representative of at least two motion variables. The motion variables are motion variables of an oscillation of the tower and/or of an oscillation of the rotor blade. Then, an operating setpoint is determined for the pitch setting system and the generator controller depending on the first information. The operating setpoint is determined such that, when the pitch setting system and/or the generator controller is operated according to the respective operating setpoint, it sets the pitch angle of the rotor blade or the generator torque, respectively, in order to damp the oscillation.