A pitch controlled wind turbine comprising a tower, a nacelle mounted on the tower, a hub mounted rotatably on the nacelle, and at least three wind turbine blades is disclosed. Each wind turbine blade extends between a root end connected to the hub via a pitch mechanism, and a tip end. The wind turbine further comprises at least three blade connecting members, each blade connecting member extending between a connection point on one wind turbine blade and a connection point on a neighboring wind turbine blade, the connection points being arranged at a distance from the root end and at a distance from the tip end of the wind turbine blade. The wind turbine further comprises at least three pre-tension members, each pre-tension member being connected to one of the blade connecting members and to a hub part, the pre-tension members thereby providing pre-tension in the blade connecting members.

The present invention provides a to method for reinforcing a wind turbine blade, such as a root end. The root end comprises a first and a second bushing for attaching the wind turbine blade to a wind turbine hub, the bushings being located between an inner sidewall of the root end and an outer sidewall of the root end, the bushings being separated by retaining material, the method comprising forming a first injection channel in the retaining material; forming a first pressure release channel in the first retaining material, wherein the first pressure release channel is formed to be in fluid communication with the first injection channel in a region between the inner sidewall and the outer sidewall; and injecting adhesive material into the first injection channel at least until adhesive material enters the formed first pressure release channel. The invention also provides a wind turbine blade having a root end that has been reinforced using such a method. Further aspects are provided.

The invention relates to a method of prolonging pitch bearing lifetime for a wind turbine as well as the pitch bearing itself. The method comprises the steps of: stopping the rotor (4) from rotating; removing a plurality of first fastening means used for mounting the blade (5) to the outer bearing ring (24); mounting a strengthening arc structure (10) on said outer bearing ring (24), opposite the blade (5); installing a plurality of second fastening means, thereby connecting said blade (5) and said strengthening arc structure (10) to said outer bearing ring (24).

A pitch controlled wind turbine (1) comprising a tower (2), a nacelle (3) mounted on the tower (2), a hub (4) mounted rotatably on the nacelle (3), and at least three wind turbine blades (5) is disclosed. Each wind turbine blade (5) extends between a root end (6) connected to the hub (4), and a tip end (7). The wind turbine (1) further comprises at least three blade connecting members (8), each blade connecting member (8) extending between a connection point (9) on one wind turbine blade (5) and a connection point (9) on a neighbouring wind turbine blade (5). The wind turbine blades (5) each comprises an inboard blade part (5a) comprising the root end (6) and an outboard blade part (5b) comprising the tip end (7), the inboard blade part (5a) and the outboard blade part (5b) being connected to each other at a split position (10). The split position (10) is arranged between the root end (6) and the connection point (9).

A pitch controlled wind turbine comprising a tower, a nacelle mounted on the tower, a hub mounted rotatably on the nacelle, and at least three wind turbine blades is disclosed. Each wind turbine blade extends between a root end connected to the hub via a pitch mechanism, and a tip end. The wind turbine further comprises at least three blade connecting members, each blade connecting member extending between a connection point on one wind turbine blade and a connection point on a neighboring wind turbine blade, the connection points being arranged at a distance from the root end and at a distance from the tip end of the wind turbine blade. The wind turbine further comprises at least three pre-tension members, each pre-tension member being connected to one of the blade connecting members and to a hub part, the pre-tension members thereby providing pre-tension in the blade connecting members.

The present invention relates to a root end assembly (100) for incorporating a plurality of fastening members (74) into the root end of a wind turbine blade shell part during a moulding operation. The root end assembly (100) comprises a mounting plate (70) with a plurality of apertures (72) and a plurality of sheath members (83), each sheath member being disposed in a respective aperture of the plurality of apertures (72). Connection members (78) are received in the sheath members (83), and a plurality of said fastening members (74) are releasably attached to a respective connection member of the plurality of connection members (78) such that the fastening members (74) extend substantially normal to a first surface (77) of the mounting plate (70). The apertures (72) are dimensioned for allowing translational movement of the sheath members (83) in the respective apertures (72).

A root assembly of a wind turbine blade for a wind turbine is provided. A wind turbine blade including the root assembly and a wind turbine including the wind turbine blade are also provided.

The invention relates to a method for securing a bushing in a blade root of a wind turbine blade according to the preamble of claim 1. The method is known in the state of the art. The known method uses an additional cavity in axial direction of the blade root. The cavities in axial and radial direction are used for accommodation of a T-bolt type bushing. The known method is not suitable for pen-type bushing. The invention has for its purpose to provide a method, which is suitable for securing a pen-type bushing in the blade root, which method can also be used to replace an existing pen-type bushing in a blade root.

The invention relates to a method of prolonging pitch bearing lifetime for a wind turbine as well as the pitch bearing itself. The method comprises the steps of: stopping the rotor (4) from rotating; removing a plurality of first fastening means used for mounting the blade (5) to the outer bearing ring (24); mounting a strengthening arc structure (10) on said outer bearing ring (24), opposite the blade (5); installing a plurality of second fastening means, thereby connecting said blade (5) and said strengthening arc structure (10) to said outer bearing ring (24).

A bushing (42, 92) for connecting a wind turbine blade (20) to a rotor hub (18) of a wind turbine (10) including a main body (44, 94) defining a connecting end of the bushing (42, 92) for receiving a fastener (130) for securing the blade (20) to the rotor hub (18), a tubular extension (46, 96) extending distally from the main body (44, 94) and defining a tip end of the bushing (42, 92) and a central bore (52, 102) extending from the connecting end to the tip end of the bushing (42, 92) and defining a central axis (94, 104) of the bushing (42, 92). The tubular extension (46, 96) includes one or more tapered or cylindrical sections (74,124) and a tip section (76, 126) distal of the one or more tapered or cylindrical sections (74, 124) and adjacent the tip end. The tip section (76, 126) includes an outer surface and an inner surface that are substantially parallel to each other and substantially parallel to the central axis (94, 104) of the bushing (42, 92).