A method for stabilizing the rotation speed of a machine with S-characteristics is provided. The method includes calculating a target net head and a target opening to affect guide vanes of the machine, the target net head and the target opening being calculated so that the torque exerted by water flow on the turbine is null and that the machine rotates at a target rotation speed; determining a real net head to which the machine is subjected; comparing the target net head with the real net head; and adjusting the opening of the guide vanes so as to converge towards the target opening and reduce a height difference between the target net head and the real net head.

A green wind turbine system that provides continuous rotation of a propeller, to prevent stopping or critical slowing of the propeller to, which causes damage to the bearing and gear assembly, and shortens of the turbine life. The propeller includes at least two opposing hollow blades, each having a pair of reservoirs positioned with one at the tip and stem, and connected by a fluid line; a wireless hydraulic pump with a rechargeable battery, and a wireless control unit configured between the reservoirs to pump fluid that is heated and/or with anti-freeze between the reservoirs; and a nacelle with: a motion sensor, anemometer, heated reserve tank. The propeller is made with biodegradable materials; and the turbine is able to manipulate the reservoir fluids to create an imbalance within the propeller to prevent it from stopping in low or no wind conditions; and to slow down in high wind conditions.

A green wind turbine system that provides continuous rotation of a propeller, to prevent stopping or critical slowing of the propeller to, which causes damage to the bearing and gear assembly, and shortens of the turbine life. The propeller includes at least two opposing hollow blades, each having a pair of reservoirs positioned with one at the tip and stem, and connected by a fluid line; a wireless hydraulic pump with a rechargeable battery, and a wireless control unit configured between the reservoirs to pump fluid that is heated and/or with anti-freeze between the reservoirs; and a nacelle with: a motion sensor, anemometer, heated reserve tank. The propeller is made with biodegradable materials; and the turbine is able to manipulate the reservoir fluids to create an imbalance within the propeller to prevent it from stopping in low or no wind conditions; and 2) to slow down in high wind conditions.

A rotary machine includes a stator and a rotor that rotates relative to the stator in response to flow of a fluid by or through the rotor. The rotary machine also includes a control circuit configured to determine one or more operational characteristics of the electric machine. The one or more operational characteristics are indicative of a flow of the fluid or a load placed on the rotary machine, the control circuit configured to apply control signals to control one or more switches of the rotary machine to induce a magnetic field in the rotary machine that resists a force imparted on a rotor of the rotary machine from the flow of the fluid. The control signals control the one or more switches of the rotary machine to control a speed at which the rotor rotates.

In examples, a computing system is configured to detect rotor imbalance at wind turbines by (1) obtaining sets of historical-vibration data for turbines, each set comprising vibration data captured by a given turbine's multi-dimensional sensor, (2) deriving a rotor-imbalance-detection model by: (a) for each turbine, (i) transforming time segments of the turbine's historical-vibration dataset into a frequency-domain representation, and (ii) for each time segment, using the frequency-domain representation for the time segment to derive a set of harmonic-mode values for at least one frequency-range of interest, thereby deriving a time-series set of harmonic-mode values for the turbine, and (b) performing an evaluation of the time-series sets for the turbines, thereby deriving the rotor-imbalance-detection model, (3) based on received vibration data for a given turbine from a reference time, executing the derived model, thereby detecting a rotor imbalance at the given turbine, and (4) transmitting a notification of the rotor imbalance.

A wind turbine system that provides continuous rotation of a propeller, to prevent stopping or critical slowing of the propeller to, which causes damage to the bearing and gear assembly, and shortens of the turbine life. The wind turbine propeller includes at least one hollow blade having a pair of reservoirs at the top and bottom of at least one blade; a hydraulic pump and a wireless control unit configured between the reservoirs; a motion sensor, aneunometer, and heater and/or pump battery (optional). The wireless control unit commands the hydraulic pump: 1) to manipulate the fluid present within the reservoirs to create an imbalance within the hollow propeller to prevent it from stopping in low or no wind conditions; and 2) to slow down in high wind conditions. One embodiment comprises two short hollow blades with the pump, reservoirs, and control unit, and two normal long blades.

In examples, a computing system is configured to detect rotor imbalance at wind turbines by (1) obtaining sets of historical-vibration data for turbines, each set comprising vibration data captured by a given turbine's multi-dimensional sensor, (2) deriving a rotor-imbalance-detection model by: (a) for each turbine, (i) transforming time segments of the turbine's historical-vibration dataset into a frequency-domain representation, and (ii) for each time segment, using the frequency-domain representation for the time segment to derive a set of harmonic-mode values for at least one frequency-range of interest, thereby deriving a time-series set of harmonic-mode values for the turbine, and (b) performing an evaluation of the time-series sets for the turbines, thereby deriving the rotor-imbalance-detection model, (3) based on received vibration data for a given turbine from a reference time, executing the derived model, thereby detecting a rotor imbalance at the given turbine, and (4) transmitting a notification of the rotor imbalance.

A wind turbine system that provides continuous rotation of a propeller, to prevent stopping or critical slowing of the propeller to, which causes damage to the bearing and gear assembly, and shortens of the turbine life. The wind turbine propeller includes at least one hollow blade having a pair of reservoirs at the top and bottom of at least one blade; a hydraulic pump and a wireless control unit configured between the reservoirs; a motion sensor, aneunometer, and heater and/or pump battery (optional). The wireless control unit commands the hydraulic pump: 1) to manipulate the fluid present within the reservoirs to create an imbalance within the hollow propeller to prevent it from stopping in low or no wind conditions; and 2) to slow down in high wind conditions. On embodiment comprises two short hollow blades with the pump, reservoirs, and control unit, and two normal long blades.

An improved wind turbine device of present invention provides continues rotation of propeller and prevents stopping or critical slowing of the propeller of the turbine that causes damage to the bearing and gear assembly and shortens the life of the turbine. The wind turbine device or system of present invention is comprising of a novel hollow propeller blades having a pair of reservoirs at the top and bottom of the propeller blades and a hydraulic pump configured between the reservoirs within the hollow propeller blades along with the wireless control unit that commands the pump to manipulate the fluid present within the reservoirs to create an imbalance within the hollow propeller causing the hollow propeller to keep from stopping. Also, the wireless control unit commands the pump to manipulate the fluid of the reservoirs in reverse direction in high wind condition to prevent the propeller from rotating excessively that may cause damage and loss of electricity.

A controller of a wind turbine for causing the wind turbine to perform rotor turning includes: an input part for receiving a target azimuth angle at which a rotor of the wind turbine is to be stopped; and a pitch control part configured to cause the wind turbine to perform a pitch control to stop the rotor at the target azimuth angle. The pitch control part is configured to: control a pitch angle of a wind turbine blade of the wind turbine so that the rotor rotates at a predetermined rotation speed which is constant, in a first period until the rotor reaches a control-switch azimuth angle immediately before the target azimuth angle; and control the pitch angle so that a rotation speed of the rotor decreases from the predetermined rotation speed in a second period after the rotor reaches the control-switch azimuth angle and before the rotor reaches the target azimuth angle.