The present disclosure relates to devices (350) for reducing vibrations in wind turbines (10) and to methods (450) for using the devices (350) and mitigating wind turbine vibrations. More particularly, the present disclosure relates to devices (350) for reducing vortex induced vibrations and stall induced vibrations when the wind turbine (10) is parked, especially during wind turbine installation and/or maintenance, and to ways in which the devices (350) can be used, e.g. for installing them on wind turbine blades (22) or once they are already installed thereon. A vibration mitigating device (350) for mitigating vibrations of a parked wind turbine (10) is provided. The device (350) is configured to be arranged with a wind turbine blade (22). The device (350) comprises one or more air flow modifying elements (330). At least one of the air flow modifying elements (330) is configured to change between a retracted configuration (370) and an extended configuration (375).

A turner gear assembly (52) for turning an unbalanced rotor of a wind turbine (10) having a drivetrain (30). The turner gear assembly (52) includes a turner gear (50) configured to couple to the drivetrain (30) and having at least two motors (58a, 58b), and a valve block (78) connectable to the turner gear (50) and having a first flow control valve (106) configured to be in fluid communication with a pump (80) and with the at least two motors (58a, 58b). The first flow control valve (106) is selectively moveable between a first fluid control position (106a) and a second fluid control position (106b). When the first flow control valve (106) is in the first fluid control position (106a), the at least two motors (58a, 58b) operate in parallel and when the first flow control valve (106) is in the second fluid control position (106b), the at least two motors (58a, 58b) operate in series. A method of operating the turner gear assembly is also disclosed.

A system and method are provided for reducing vibrations and loads in one or more rotor blades of a wind turbine when the rotor hub is locked against rotation, The method detects that the rotor blades are vibrating above a threshold limit, and determines one or more wind parameters for wind impacting the rotor blades. An initial orientation of the blades is also determined. Based on the wind parameters and initial blade orientation, a first angle of attack for the rotor blades is determined that will reduce the vibrations in the rotor blades. The method then determines if expected loads induced at one or more wind turbine components will exceed a threshold limit at the first angle of attack for the rotor blades. The first angle of attack is modified when the expected loads exceed the threshold limit to reduce the expected loads to below the threshold limit. A controller pitches the rotor blades to achieve the first angle of attack.

A proactive method and related wind turbine system are provided for reducing vibrations in the rotor blades when the rotor hub is locked against rotation. The method includes determining an initial blade orientation to wind direction and wind parameters for wind impacting the rotor blades. Based on the wind parameters and blade orientation, an angle of attack is determined for the rotor blades that will at least reduce vibrations expected to be induced in the blades from the current wind conditions. With a controller, the rotor blades are pitched to achieve the angle of attack using a pitch control system. The angle of attack is determined and the rotor blades are pitched from the initial blade orientation to the new angle of attack prior to vibrations being induced in the rotor blades.

A lock for preventing rotation of a rotor of a wind turbine has a rotatable lock pin, a pin support supportable in a nacelle of the wind turbine and a mechanism for rotating the lock pin. The pin support has a hub-facing face proximate a rotor hub. The rotatable lock pin is rotatably mounted on the pin support. The lock pin has a cammed portion extending away from the hub-facing face toward the hub. The lock pin inserted into a complementary rotor lock aperture on the rotor hub when the pin support is supported in the nacelle. Rotation of the lock pin causes engagement of an exterior surface of the cammed portion with an interior surface of the rotor lock aperture to immobilize the lock pin against the interior surface to prevent relative motion between the lock pin and the aperture to prevent rotation of the rotor.

A main shaft fixture for fixing a main shaft on a wind turbine during installation and repair work on heavy parts of the wind turbine nacelle, in the case where the fixture is formed of several sections for mounting on stable structural parts in the nacelle, including the nacelle's bottom frame. The main shaft fixture has adjustable pressure mandrels with tap shoes, which cause the fixture to be usable regardless of the turbine main shaft geometry, such that it can be mounted without fixing the rotor. The main shaft fixture also has facilities for mounting of a lightweight crane and a self-hoisting crane with a ground-based winch, respectively, as well as a rotor lock which, in combination with actuators of the main shaft fixture, enables the main shaft and the main shaft bearing to be sufficiently displaced vertically from its bearing in the nacelle to service or replace the bearing.

A rotor rotation control system for a wind turbine and a control method thereof are provided. The control system includes a rotation unit configured to drive a rotor of the wind turbine to rotate relative to an engine base of the wind turbine, a driving unit configured to drive the rotation unit, and a processor configured to determine a bending moment load switching position on a rotating shaft of the rotor, and output an adjustment instruction to the driving unit based on the bending moment load switching position.

The invention generally relates to two-bladed turbine nacelles and platforms integrated into the nacelle structure. In certain embodiments, the invention provides an assembly encompassing a nacelle that houses a two-bladed turbine and a hoisting platform. The hoisting platform is integrated into the structure of the nacelle so as to form the roof of the nacelle.

A rotor turning system includes a fixture plate configured for attachment to a gearbox, a locking mechanism configured for attachment to the fixture plate, and a reaction fixture configured for attachment to the locking mechanism. The rotor turning system is configured to permit rotation of the rotor only when rotational torque is applied to the locking mechanism, and this rotation is in only one rotational direction.

An arrangement and a method of rotating a hub of a wind turbine are provided. A wind turbine includes a hub mounted to a nacelle, whereby the hub is rotatable around an axis of rotation in respect to the nacelle. A rotor blade is arranged at the hub that leads to a torque around the axis of rotation of the hub. A counter weight is attached to the hub, whereby the counter weight has a mass that leads to a counter-torque around the axis of rotation. The counter-torque interacts with the torque during the installation of a second rotor blade to the hub. The counter weight is mounted to the hub by a mechanical arrangement that is rotatable in respect to the hub around the axis of rotation of the hub. The mechanical arrangement and the counter weight are rotatable in respect to the hub into a certain predetermined position.