A wind turbine arrangement including a first rotatable blade arrangement and a second rotatable blade arrangement. The first blade arrangement forms part of a first wind turbine, and the second blade arrangement forms part of a second wind turbine. The second wind turbine can produce a rotative force to the first wind turbine. At wind speeds below that required to operate the first turbine, the second turbine may be operable and provide power to rotate the first turbine.

A wind turbine includes a plurality of wind turbine blades; a plurality of hydraulic actuators for controlling respective pitch angles of the wind turbine blades; a first tank storing control oil for the hydraulic actuators; a first hydraulic pump disposed between the plurality of hydraulic actuators and the first tank, for pumping the control oil; a plurality of valves each of which is provided for corresponding one of the hydraulic actuators, for controlling a supply state of the control oil to the hydraulic actuator; and a control part for controlling each of the valves. The control part is configured to, in warm-up of a pitch hydraulic system of the plurality of wind turbine blades, perform an oil transfer operation of changing the pitch angle of the wind turbine blade from a feather side toward a fine side and then returning the pitch angle to the feather side.

The invention concerns a method for coupling to the grid a hydraulic unit having a synchronous generator, a runner, and wicket gates, the method comprises: a) a step of increasing the flow of water into the runner from a time t.sub.0 to a time t.sub.1 so that the rotation frequency of the rotor of the synchronous generator is, at time t.sub.1 equal to the frequency of the grid; b) a step of closing the circuit breaker at time t.sub.1, step a) further comprises a sub-step a1) executed from a time t.sub.2 to time t.sub.1, wherein the flow of water is adjusted so that, at time t.sub.1, the phase of the synchronous generator is aligned with the grid phase.

A method for initializing startup of a wind turbine includes measuring, via one or more sensors, a first wind condition at the wind turbine at a first moment in time. The method also includes measuring, via the one or more sensors, a second wind condition at the wind turbine at a subsequent, second moment in time. Further, the method includes estimating, via the processor(s), an acceleration parameter of the wind turbine as a function of the first wind condition and the second wind condition. Moreover, the method includes comparing, via the processor(s), the acceleration parameter to a predetermined threshold. As such, the method includes initializing, via the processor(s), a first startup process for the wind turbine when the acceleration parameter is at or below a predetermined threshold. Further, the method includes initializing, via the processor(s), a second startup process for the wind turbine when the acceleration parameter exceeds a predetermined threshold, the second startup process being faster than the first startup process.

A gentle start-up device includes: a rotational type hollow pipe body, including an inlet and an outlet, and having an inner wall provided with a plurality of bar-shaped fins; a transmission unit, physically connected to the rotational type hollow pipe body; and a driving unit, physically connected to the transmission unit for driving the transmission unit to rotate the rotational type hollow pipe body in a rotational direction and to achieve a predetermined rotational speed according to a water supply flow value of a water turbine of a hydraulic generator set, whereby water flow which passes through the rotational type hollow pipe body generates rotational flow.

A method for starting a farm grid of a wind farm is provided. The energy generation grid has at least one grid connection point connected to an electrical supply grid and the energy generation grid, in a normal operating mode, exchanges electrical power with the electrical supply grid via the grid connection point. The method includes selecting an establishment mode, different than the normal operating mode, if the electrical supply grid has a voltage drop or the energy generation grid is isolated from the electrical supply grid and operating the energy generation grid in the establishment mode. The establishment mode at least one voltage-influencing wind power installation for providing a wind farm grid voltage and at least one current-influencing wind power installation that synchronizes to the energy generation grid voltage. The wind power installations in total provide an electrical power at the level of an inherent need of the grid.

A vertical axis turbine having a first rotor and at least one second rotor, the first rotor being configured to rotate around a first rotation axis that is vertical or more vertical than horizontal. The first rotor may be configured to be driven and/or rotated by wind or water flow. The at least one second rotor is provided on or coupled to the first rotor such that the first rotor is operable to move the second rotor upon rotation of the first rotor. The second rotor is operable to drive a power take off system. Each second rotor rotates around a respective second rotation axis that may be angled or perpendicular to the first rotation axis of the first rotor. The first and second rotors are configured so that the power take-off system can be driven without the need for a gearbox.

A method for starting a wind turbine with hinged wind turbine blades, the wind turbine further comprising an adjustable biasing mechanism arranged to apply an adjustable biasing force to each wind turbine blade which biases the wind turbine blade towards a position defining a minimum pivot angle. The biasing mechanism is adjusted to apply a predefined biasing force to each wind turbine blade, and the pivot angle of each wind turbine blade is monitored. The wind turbine is started in the case that the pivot angle of at least one wind turbine blade exceeds a predefined pivot angle threshold.

A wind turbine includes a rotation axis suited to be positioned in space in any way and N blades indirectly constrained to the axis through one or more radial arms that are integral with the axis, wherein the blades can translate in a radial direction with respect to the axis during the rotation of the blades.

A wind turbine power generating apparatus includes a wind turbine rotor including at least one blade; a pitch drive part for changing a pitch angle of the at least one blade; a generator configured to be driven by rotational energy of the wind turbine rotor; a circuit breaker for switching a connection state of the generator with respect to a utility grid; and a controller for controlling the wind turbine power generating apparatus. The controller includes a pitch control part configured to control the pitch drive part in a constant rotation-speed control mode for maintaining a rotation speed of the wind turbine rotor at a target rotation speed, before connection of the generator; a connection-condition determination part configured to determine whether a connection determination condition is satisfied; and a connection-command generation part configured to provide the circuit breaker with a connection command to connect the generator to the utility grid.