A method for monitoring at least one rotor blade of a wind turbine includes implementing, via a controller, a control scheme for monitoring blade damage of the at least one rotor blade. The control scheme includes monitoring at least one electrical condition of a pitch system of the wind turbine. The method also includes converting the electrical condition(s) of the pitch system into a frequency domain. Further, the method includes determining one or more peaks of the frequency domain around a frequency component related to a natural frequency of the rotor blade. Moreover, the method includes determining a frequency deviation between the one or more peaks of the frequency domain and the frequency component related to the natural frequency of the rotor blade. As such, a frequency deviation outside of a predetermined frequency range is indicative of a rotor blade anomaly. Thus, the method includes implementing a control action when the frequency deviation is outside of the predetermined frequency range.

A multiple rotor (MR) wind turbine comprising a tower (21) extending in an upwards direction, a load carrying structure (22) extending in an outwards direction and being fixed to the tower, and an energy generating unit (54) fixed to the load carrying structure, wherein the outwards direction is transverse to the upwards direction, the wind turbine further comprising a hoisting line (53) for communication of objects (52) to and from the energy generating unit (54), the hoisting line being windable from an attachment point (55) of the load carrying structure or from the energy generating unit. To allow positioning of hosted objects near the tower, or at selectable distance from the tower, the hoisting line extends from the attachment point via a suspension point (56) to a lifting point (57) where the object (52) can be attached, and the suspension point (56) is movable outside the load carrying structure.

The invention provides a method for monitoring health state of blade root fastener, comprising the following steps: obtaining a sequence of acceleration signals representing the lateral vibration of the nacelle and a sequence of rotational speed signals representing the rotational speed of the rotor; analyzing the sequence of acceleration signals and the sequence of rotational speed signals to determine the amplitude of the nacelle at 2-time-frequncy of the rotational speed of the rotor; and determining the health state of the blade root fastener based on the amplitude. The invention also provides a system for monitoring the health state of the blade root fastener. Through the present invention, the health state of the blade root fastener can be determined with low cost and high precision, thereby improving the operation efficiency and operation safety of the wind turbine.

The present disclosure is directed to an internal reinforcement assembly for a tower of a wind turbine. The reinforcement assembly includes a plurality of reinforcing rod members spaced circumferentially about the tower. Each of the plurality of reinforcing rod members includes a first end and a second end. The reinforcement assembly also includes an adjustable mounting component configured with each of the second ends of the plurality of reinforcing rod members. As such, the adjustable mounting components are mounted to an interior wall of the tower at a location to be reinforced. Thus, the reinforcing rod members interact with the tower to reinforce the tower at the location to be reinforced.

The present disclosure is directed to an internal reinforcement assembly for a tower of a wind turbine. The reinforcement assembly includes a plurality of reinforcing rod members spaced circumferentially about the tower. Each of the plurality of reinforcing rod members includes a first end and a second end. The reinforcement assembly also includes an adjustable mounting component configured with each of the second ends of the plurality of reinforcing rod members. As such, the adjustable mounting components are mounted to an interior wall of the tower at a location to be reinforced. Thus, the reinforcing rod members interact with the tower to reinforce the tower at the location to be reinforced.

A system and method are provided for reducing vibrations and loads in one or more rotor blades on a rotor hub of a wind turbine when the rotor hub is in a locked or idling condition. An electronically tunable mass damper is attached to a fixed location on one or more of the rotor blades. The mass damper is maintained on the rotor blades during the locked or idling condition of the rotor hub. The method includes sensing movement of a mass component of the mass damper from vibrations or oscillations induced in the rotor blade. The mass damper is automatically tuned based on the sensed movements of the mass component by automatically varying an electrical characteristic of the mass damper.

A system and method are provided for reducing vibrations and loads in one or more rotor blades on a rotor hub of a wind turbine when the rotor hub is in a locked or idling condition. An electronically tunable mass damper is attached to a fixed location on one or more of the rotor blades. The mass damper is maintained on the rotor blades during the locked or idling condition of the rotor hub. The method includes sensing movement of a mass component of the mass damper from vibrations or oscillations induced in the rotor blade. The mass damper is automatically tuned based on the sensed movements of the mass component by automatically varying an electrical characteristic of the mass damper.

A method of handling the pitch bearing unit of a rotor blade mounted to the hub of a wind turbine, the method including the steps of providing an extension assembly at the interface between the rotor blade and the hub, moving the rotor blade outward from the hub by means of the extension assembly to open a gap large enough to accommodate the pitch bearing unit while maintaining a connection between the rotor blade and the hub, and removing the pitch bearing unit through the gap.

A vertical axis wind turbine system having a vertical mast with one or more turbine units supported thereon. The turbine units are of modular construction for assembly around the foot of the mast; are vertically moveable along the height of the mast by a winch system; and are selectively interlocking with the mast to fix the turbine units in parked positions. The turbine system and each turbine unit includes a network of portals and interior rooms for the passage of personnel through the system, including each turbine unit. The electrical generators, and other sub-components, in the turbine units are of modular construction that permits the selective removal and replacement of component segments, including the transport of component segments through the portals and interior rooms of the turbine system while the turbine units remain supported on the mast. The electrical generators are also selectively convertible between AC generators and DC generators.

A method for assembling a wind turbine, including: attaching an elevator carriage (27) to a nacelle (9) to form a carriage-nacelle assembly (27,9); and mounting the carriage-nacelle assembly (27,9) on to a tower (3) as a unit.