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).

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).

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.

The invention relates to a method for controlling a wind power installation which has a rotor having rotor blades that are adjustable in terms of their blade angle, and having a rotor diameter, wherein the rotor is able to be operated at a variable rotor rotating speed; and a region in which the rotor blades move forms a danger zone for birds and bats, the method comprising the following steps: checking whether a bird or bat approaching the wind power installation is an endangered bird and if an endangered bird has been identified, detecting a bird position as the current position of the endangered bird identified; and controlling the rotor rotating speed as a function of the bird position in relation to the wind power installation; wherein the rotor rotating speed is reduced in multiple stages or continuously as the distance of the bird position from the wind power installation decreases. The invention is intended to propose a solution in which a wind power installation poses the lowest possible risk to endangered species of birds and bats while at the same time offering the best possible yield. The intention is to at least propose an alternative to the solutions known to date.

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.

There is presented a method for controlling a rotor on a wind turbine, wherein the rotor is comprising one or more blades, and wherein the wind turbine is comprising a pitch system, the method comprising: Operating the rotor in a standstill or idling operating state, determining or receiving one or more control parameters, where the control parameters enable determining one or more yawing parameters may be described as a function of the one or more control parameters, wherein the one or more yawing parameters comprises one or more of: An angular yawing velocity of the a yawing section, an angular yawing acceleration of the yawing section, and/or a yawing moment applied by the yawing section on a remainder of the wind turbine, and pitching based on the one or more control parameters one or more blades of the rotor with the pitch system.

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.

Described herein are wave energy conversion systems including actuated geometry components. An example system may include at least one body portion configured to transfer wave energy to a power take off device, and at least one actuated geometry component that is connected to the at least one body portion, the at least one actuated geometry component operable to modify a geometric profile of the system.

A method for detecting a shadow condition from a wind turbine and a system for detecting a shadow condition are provided. An atmospheric condition detected from an atmospheric condition detector is compared to a threshold. From the comparison a determination is made that the atmospheric condition is shadow producing. The shadow condition is detected using the determination.

A turbine controller system and method for a fluid-driven power generation unit may include an electrical circuit that connects to a power source and a rotor of a generator of the fluid-driven power generation unit. A turbine control circuit, which may include multiple circuits, may receive data from sensors or from external sources and may generate a signal to control the generator based on a determination that at least one weather condition exists. Control may be effectuated by motoring the rotor of the generator to mitigate a potential impact of the determined at least one weather condition on the fluid-driven power generation unit.