A hydroelectric generation system includes a fluid machine disposed in a penstock or channel, a generator driven by the fluid machine, and a control unit configured to generate a predetermined torque in the generator. Fluid flows through the penstock or channel. The penstock or channel has a main path in which the fluid machine is disposed, and a detour disposed in parallel with the main path. The detour includes an on-off valve. The on-off valve is opened when not electrified, and closed when electrified.

A wind turbine comprises a permanent magnet synchronous generator, a main converter, a main converter controller, a wind turbine master controller and an electrical power supply stage comprising an electrical energy storing device. A startup of the wind turbine can be performed using electrical energy from the electrical energy storing device independent from a power supplying grid and/or a combustion engine. After startup, the wind turbine can be operated in an island mode by controlling an intermediate voltage of the main converter by the main converter controller and retrieving power from the synchronous generator independent from the electrical energy storing device.

The invention relates to control of a wind turbine comprising a plurality of multi-axial accelerometers mounted at different positions in the nacelle and/or in a top portion of the tower. The position and orientation of each accelerometer as mounted is obtained, accelerations in at least two different directions by each accelerometer are measured during operation of the wind turbine. From a number of predetermined mode shapes for the movement of the wind turbine is then determined an absolute position of at least one of the accelerometers during operation of the wind turbine based on the measured accelerations, the mount position and orientation of each accelerometer and the pre-determined mode shapes. Hereby a more precise absolute position during operation is obtained which can be used in the controlling of the turbine.

A hydroelectric generation system includes a fluid machine disposed in a penstock or channel, a generator driven by the fluid machine, and a control unit configured to generate a predetermined torque in the generator. Fluid flows through the penstock or channel. The penstock or channel has a main path in which the fluid machine is disposed, and a detour disposed in parallel with the main path. The detour includes an on-off valve. The on-off valve is opened when not electrified, and closed when electrified.

A method for controlling a wind turbine comprising inputting an actual value of rotational speed and a rotational speed setpoint into a control and outputting a set point value for a generator torque from the control. Inputting the set point value for the generator torque into a limiter with a predefinable upper and lower limit and outputting a limited torque value that is fed into a converter control. Increasing the actual value of the fed-in electrical power by an additional amount of power in response to a boost signal, wherein the fed-in electrical power and the additional amount of power are combined into an aggregated power setpoint value. Determining the set point value for the generator torque from the aggregated power setpoint value and applying the set point value for the generator torque in the boost operation to the limiter both as the upper limit and as the lower limit.

A method for operating a wind turbine includes: determining a value of a wind speed of an incident air mass at the wind turbine; if the determined value of the wind speed is greater than a first threshold value for the wind speed: reducing a rotational speed of a rotor of the wind turbine, and maintaining or increasing a generator torque acting upon the rotor; if the determined value of the wind speed is greater than a second threshold value for the wind speed, the second threshold value being greater than the first threshold value: reducing the rotational speed of the rotor, and reducing the generator torque acting upon the rotor.

A method for operating a wind turbine connected to a power grid in response to one or more grid events occurring in the power grid includes monitoring, via one or more sensors, the power grid (such as a frequency thereof) so as to detect one or more grid events occurring in the power grid. In response to detecting one or more grid events occurring in the power grid, the method includes increasing mechanical inertia of a rotor of the wind turbine during a first time frame after one or more grid events occurs in the power grid. After the first time frame, the method includes providing a required additional power output to the power grid during a subsequent, second time frame so as to stabilize the power grid after one or more grid events occurs in the power grid.

A system includes a wind turbine a wind and a first control device for controlling the wind turbine. The first control device is configured to acquire a yaw misalignment of the wind turbine, which yaw misalignment is a difference between the actual yaw angle and a wind direction at the wind turbine; and to determine at least one of a target pitch angle of the blade and a target torque of the generator based on the yaw misalignment to optimize a power output from the wind turbine. Further, a wind farm includes the system and a method of controlling a wind turbine.

A downhole turbine includes a plurality of fins. The plurality of fins have an exit angle that exerts a tangential force on the fin, which imparts a torque on a hub. The fins have an adjustable exit angle that changes in response to changes in the properties of a drilling fluid. The changing exit angle changes the tangential force, which changes the torque on the hub.

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.