A method for performing maintenance on an outer surface of at least one wind turbine part, such as a tower (2), a nacelle (3) or a wind turbine blade (5), of an offshore wind turbine (1) is disclosed. An access system (10) is transported to a site of the offshore wind turbine (1), and the access system (10) is transferred to a transition platform (6) at a lower part of the offshore wind turbine (1), while operating the offshore wind turbine (1) in accordance with a normal operating mode. Normal operation of the offshore wind turbine (1) is then stopped, and maintenance is performed on an outer surface of at least one wind turbine part (2, 3, 5) of the offshore wind turbine (1), using the access system (10). When the maintenance has been completed, normal operation of the offshore wind turbine (1) is restarted in accordance with a normal operating mode. Normal operation of the offshore wind turbine (1) is only stopped while the actual maintenance takes place. Thereby the loss in power production is minimised.

A method for performing maintenance on an outer surface of at least one wind turbine part, such as a tower (2), a nacelle (3) or a wind turbine blade (5), of an offshore wind turbine (1) is disclosed. An access system (10) is transported to a site of the offshore wind turbine (1), and the access system (10) is transferred to a transition platform (6) at a lower part of the offshore wind turbine (1), while operating the offshore wind turbine (1) in accordance with a normal operating mode. Normal operation of the offshore wind turbine (1) is then stopped, and maintenance is performed on an outer surface of at least one wind turbine part (2, 3, 5) of the offshore wind turbine (1), using the access system (10). When the maintenance has been completed, normal operation of the offshore wind turbine (1) is restarted in accordance with a normal operating mode. Normal operation of the offshore wind turbine (1) is only stopped while the actual maintenance takes place. Thereby the loss in power production is minimised.

A wind generator includes a revolving platform rotationally connected with a base; a tower body, where a bottom end of the tower body is connected to the revolving platform, a top end of the tower body is fixedly provided with a generator room, and a plurality of blades are rotationally connected to the generator room through a wheel hub; and the tower body is provided with at least one windward side in the circumferential direction of the tower body, and a bending stiffness of the windward side is not less than that of the remaining sides of the tower body; and a power source, where the power source is started when airflow is to the sides rather than the windward side to enable the airflow to flow to the windward side while the windward direction of the blades coincides with the airflow. A wind generator group is further provided.

A floating power-generation group comprises a floating hub such as a spar buoy that is anchored to subsea foundations by anchor lines. Floating power producer units such as wind turbines are connected electrically and mechanically to the hub. The power producer units are each moored by mooring lines. At least one mooring line extends inwardly toward the hub to effect mechanical connection to the hub and at least one other mooring line extends outwardly toward a subsea foundation. The groups are combined as a set whose hubs are connected electrically to each other via subsea energy storage units. Anchor lines of different groups can share subsea foundations. The storage units comprise pumping machinery to expel water from an elongate storage volume and generating machinery to generate electricity from a flow of water entering the storage volume. The pumping machinery may be in deeper water than the generating machinery.

Protection for a cable, piping or tubing comprises a bend stiffener. This includes at least one element comprising a tubular wall having a substantially smooth inner surface, which defines circumferential recesses along at least part of its length. Each recess has an open end at the circumference of the wall, a base, and sloping sides that are closer to each other at the base than at the open end. Each recess has a depth of no more than 50% of the thickness of the tubular wall. The bend stiffener may include a number of such elements connected together. The cable protection may also include a clamp attached to the bend stiffener.

A transport apparatus for use in the transport of a heavy structure includes a shape-adjustable adapter realized to adjust between an initial shape and a mating shape; and an actuator configured to effect a change in shape of the shape-adjustable adapter into its initial shape to facilitate positioning of the adapter relative to the structure; and to effect a change in shape of the shape-adjustable adapter into its mating shape to engage the shape-adjustable adapter with a surface of the structure. A method of securing a frustoconical structure during transport is further provided.

A wind turbine offshore installation method of installing a wind turbine using a semi-submersible type floating substructure includes: a step of towing the semi-submersible type floating substructure on which the wind turbine is erected to an installation target site on a sea; and a step of coupling the wind turbine and a spar type floating substructure for supporting the wind turbine on the sea at the installation target site to install the wind turbine on the sea.

A wind turbine offshore installation method of installing a wind turbine using a semi-submersible type floating substructure includes: a step of towing the semi-submersible type floating substructure on which the wind turbine is erected to an installation target site on a sea; and a step of coupling the wind turbine and a spar type floating substructure for supporting the wind turbine on the sea at the installation target site to install the wind turbine on the sea.

The invention relates to a structure (2) for supporting a wind turbine tower (1) provided with a housing (7) for fitting therein the foot of the tower (1), a main axis (Γ) being defined on the platform (2) which coincides with a main axis of the tower (1), and which comprises a body with a constant cross-section and internal walls (8) and intermediate walls (10) joined by internal radial ribs (11) perpendicular to the internal wall (8) whose plane passes through the main axis (Γ), such that at the intermediate wall (10) first joining nodes (12) are defined between the intermediate wall (10) and radial ribs (11), the intermediate wall (10) and an external wall (9) being joined by reticular ribs (14 and 15). This structure provides an optimal transmission of forces. The invention likewise relates to methods for manufacturing, assembling and installing the structure.

A support structure for a wind power generation device comprises: a plurality of floats that can float on the surface of water or in the water; a connecting member having one end connected to one of the floats and the other end connected to another of the floats among the plurality of floats; a support platform that is provided between the plurality of floats and supports the bottom end of a tower part of the wind power generation device; a linear wire member having one end connected to one of the floats and the other end connected to the support platform; and a support member that is provided on the floats or on the connecting member and supports the tower part, which is supported on the support platform, from a lateral direction while the support member being movable along the axial direction of the tower part.