There is presented a method (320) for controlling a wind turbine (100), wherein said wind turbine comprises a wind turbine rotor (102) with one or more blades (103), wherein the wind turbine has a rated angular rotation speed (214) of the wind turbine rotor, said method comprising obtaining (322) information (323) on ambient conditions, determining, based on said information, if an erosion criterion is fulfilled, controlling (328) the wind turbine according to an extended mode if the erosion criterion is fulfilled, wherein in the extended mode an angular rotation speed of the wind turbine rotor is allowed to exceed the rated angular rotation speed (214).

Methods of operating a variable speed wind turbine as a function of wind speed are described. The wind turbine has a rotor with a plurality of blades and a generator. The generator has a design rotor speed which varies so as to follow a theoretical generator rotor rotational speed curve describing the rotational speed of the rotor as a function of wind speed. The method comprises determining an erosion risk condition of the blades, determining erosion damage of one or more of the blades accumulated over time and changing the rotor rotational speed from the design rotor speed as a function of the determined erosion risk condition and the determined accumulated erosion damage. Wind turbines configured to carry out such methods are also described.

A method for operating a wind farm having a first wind power installation and a second wind power installation, to an associated wind power installation and to an associated wind farm. The second wind power installation is located in the wake of the first wind power installation in at least one wake wind direction. A tip-speed coefficient is determined from the ratio of a second tip-speed ratio of the second wind power installation and a first tip-speed ratio of the first wind power installation and a pitch-angle coefficient is determined from the ratio of a second pitch angle of the second wind power installation and a first pitch angle of the first wind power installation. The method comprises: determining a turbulence metric, in particular a turbulence intensity, at the second wind power installation; operating the first wind power installation and the second wind power installation in the wake wind direction in a part-load range, wherein the tip-speed coefficient and/or the pitch-angle coefficient are/is a function of the turbulence metric at the second wind power installation and are/is greater than one.

A system for capturing fluid energy has a blade shaft coupled to a gear assembly and a blade assembly. The blade assembly has a rod arm and a blade having a front surface and a blade plane, the blade fixedly coupled substantially normal to the rod arm. A limiter coupling has a limiter coupling axis and is coupled to the blade such that the limiter coupling axis is substantially parallel to the front surface and perpendicular to the rod arm. A horizontal limiter restricts the limiter coupling to a range of motion substantially along a first movement axis perpendicular to the limiter coupling axis and substantially perpendicular to the blade shaft. The blade assembly interacts with a fluid flow to transmit fluid energy from the fluid flow to the blade shaft to impart rotational energy to the gear assembly.

The present disclosure is directed to a system for determining a torque exerted on a shaft of a wind turbine. The system includes a gearbox coupled to the shaft. The gearbox includes a first arm and a second arm. First and second fluid dampers respectively couple to the first and second arms of the gearbox. A first fluid conduit fluidly couples the first and second fluid dampers. A first pressure sensor is in operative association with the first fluid conduit to detect a fluid pressure of fluid within the first fluid conduit. A controller communicatively couples to the first pressure sensor. The controller is configured to determine the torque exerted on the shaft based on signals received from the first pressure sensor.

The present invention provides improvement of the operation of a wave energy system by use of a method for predictive control (COM) of the converter machine that maximizes the energy generated by considering the energy conversion efficiency (MOD ENE) and a wave prediction (PRED). Furthermore, the method according to the invention determines the optimal control by minimizing an objective function weighted and discretized by the trapezoidal rule.

Provided is a control arrangement for controlling an electrical machine, including: a fundamental current controller, at least one harmonic flux controller related to a harmonic of an electrical frequency of the electrical machine, a summation system for adding voltage commands to obtain a summed voltage command based on which the electrical machine.

A system for generating its own air currents to run electric turbines. The system includes: a vertical tower or support provided with a rotating disk at its upper end, up to four laterally extending arms connected to the disk, each arm carrying a wind turbine generator with rotating blades/rotors attached at its outer end, a planetary gear system having a central sun gear and motor associated with the rotating disk and a main controller system connected to the vertical tower base, wherein the main control system controlling the startup input source from a state power supply system and a solar system supply operating the central motor.

The invention relates to the real-time determination of the forces applied by waves incident upon the moving part (2) of a wave-energy system (1). The method according to the invention is based on the construction of a model of the radiation force applied to the moving part (2) and a model of the dynamics of the wave-energy system (1). The invention uses only measurements of the kinematics of the moving part (2) and the force applied by the conversion machine (3) to the moving part (2).

A wind turbine which is configured to be disposed in or above a sea floor is provided. The wind turbine includes a tower configured to protrude from a sea level and having a transmitter configured to transmit an electromagnetic wave to be reflected on the sea level and a receiver configured to receive the reflected electromagnetic wave, wherein at least one of the transmitter and the receiver includes a leaky feeder; and a processing unit being in communication with the receiver and configured to analyse the reflected electromagnetic wave such that a wave characteristic of the sea level is determined.