Abstract: A method is provided for controlling the shutdown of a wind turbine of the type having a rotor, the rotor comprising one or more wind turbine blades. The method comprises dynamically determining a rotor speed reference; obtaining a measure of the rotor speed of the rotor; determining an error between the rotor speed reference and the rotor speed of the rotor; and controlling a pitch of one or more of the wind turbine blades based on the determined error. A corresponding wind turbine controller and a wind turbine including such a controller are also provided.

Abstract: There is provided a method for controlling a hydraulic pitch force system (220) so as to reduce or eliminate a decrease in hydraulic oil pressure (241) if a hydraulic system parameter value is outside a hydraulic system parameter range, the method comprising: Obtaining (690) the hydraulic system parameter value, and operating the hydraulic pitch force system (220) according to a reduced mode (692) if the hydraulic system parameter value is outside the hydraulic system parameter range, wherein in the reduced mode one or more pitch based activities are reduced (694) or suspended. An advantage thereof may be that it enables keeping the wind turbine in production in certain instances rather than shutting down the wind turbine. In aspects, there is furthermore presented a computer program product, a pitch control system (250) and a wind turbine (100).

Abstract: A load carrying structure (3) for a multirotor wind turbine (1) is disclosed. The load carrying structure (3) comprises a first load carrying arrangement (4) and a second load carrying arrangement (4), and each load carrying arrangement (4) comprises a primary structure (9) and at least two secondary structures (10), the secondary structures (10) extending on opposing sides of the primary structure (9) between an energy generating unit (5) carried by the load carrying arrangement (4) and an attachment point at a tower structure (2). Gravity acting on the energy generating units (5) causes push in the primary structures (9) and pull in the secondary structures (10), thereby causing preload of the secondary structures (10). The load carrying structure (3) is capable of handling thrust loads.

Abstract: A wind power plant includes a plurality of wind turbine systems arranged in rows and columns and includes a cable support system with at least one cable. The cable is coupled to the support structure above the first wind turbine and below the second wind turbine. The cable couples directly adjacent wind turbine system together. The cable may extend the entire length of at least one row or at least one column. A wind turbine system includes a plurality of wind turbines and a support structure including a tower and support arms. The cable support system that is coupled to the wind turbine system and that is configured to transfer loads on the wind turbine system to other wind turbine systems in the wind power plant.

Abstract: A wind turbine system comprising a plurality of wind turbine modules mounted to a support structure, wherein each of the wind turbine modules comprises a rotor including one or more variable-pitch blades, each defining a respective blade pitch angle and being controlled by a pitch control system, and a control system operable to control the blade pitch angles of the plurality of blades of the wind turbine modules. The control system is configured to identify the presence of a predetermined stop condition and, in dependence thereon, is operable to control the blade pitch angles of the respective blades to predetermined stop positions that reduce oscillation of the support structure. Aspects of the invention also relate to a method of controlling a wind turbine system, to a controller for implementing the method, and to a computer program product.

Abstract: A method for erecting a multirotor wind turbine (10) is disclosed. A carrier structure (1, 1a, 1b) is arranged circumferentially with respect to a tower structure (2) and hoisted to an upper part of the tower structure (2), using a hoisting arrangement, such as a wire winch arrangement (3, 4, 8). Furthermore, energy generating units (5) may be hoisted to the carrier structure (1, 1a, 1b) using the hoisting arrangement (3, 4, 8). A similar method for dismantling a multirotor wind turbine (10) is also disclosed. The multirotor wind turbine (10) can be erected or dismantled without the need for an external crane.

Abstract: The present invention provides a segmented pitch ring for use in a blade pitch system of a wind turbine. The segmented pitch ring is formed of a plurality of segments manufactured by different processes. In particular, one or more of the segments are formed by a rolling process, and one or more of the segments are formed by a casting process. The segments are arc-shaped or include arc-shaped sections that in combination define a substantially circular circumference of the pitch ring.

Abstract: The present invention relates to a hydraulic pitch system for pitching a blade of a wind turbine having a hub by means of a hydraulic fluid. The system comprises at least one hydraulic cylinder for adjusting a pitch angle of the blade, the hydraulic cylinder comprising a pitch piston movable in the hydraulic cylinder, and a first port and a second port arranged on each side of the pitch piston, and an accumulator hydraulically connected to the cylinder. The system further comprises a pitch safety system adapted to maintain the blade in a predetermined pitch angle when a person is entering the hub of the wind turbine for service and/or maintenance, the pitch safety system comprising a first valve which by activation releases a pressure in the hydraulic pitch system by draining off the accumulator for the hydraulic fluid until the pressure has reached a predetermined pressure level.

Abstract: The invention provides a wind turbine including a nacelle, a rotor having at least one blade attached to a hub, and an electrical supply structure for supplying electrical power from the nacelle to the rotor. The rotor is rotatably connected to the nacelle about an axis of rotation. The supply structure comprises a switch which has a connected mode in which the nacelle and the rotor are electrically connected, and a disconnected mode in which the nacelle and the rotor are electrically disconnected. Furthermore, the switch is adapted to change from the disconnected mode to the connected mode when the rotor does not rotate.

Abstract: A wind turbine nacelle configured for mounting on a wind turbine tower and for supporting a rotor assembly, the nacelle comprising at least a first and a second nacelle module. The first nacelle module comprises a first frame structure and a main bearing system for a main shaft of the rotor assembly, and the second nacelle module comprises a second frame structure and a drive train system for the wind turbine. When the nacelle is mounted on the wind turbine tower, the main bearing system is supported by the wind turbine tower, and the drive train system is attached to the main bearing such that the weight of the drive train system is transferred to the main bearing system and thereby to the wind turbine tower.

Abstract: The invention provides a hub for a wind turbine, the hub comprising a continuous shell being assembled from at least two shell parts. To improve stiffness of the hub, a plate element is attached within blade flanges of the assembled hub. Due to the combination between shell parts and a plate element, manufacturing and transportation is facilitated while strength and rigidity is ensured.

Abstract: A pitch system (20) for rotating a blade (4) of a wind turbine relative to a hub (6) generally comprises a bearing (22) having an inner bearing ring (30) configured to be mounted to the hub and an outer bearing ring (32) configured to be mounted to the blade. A first coupling member (24) positioned between the hub and inner bearing ring extends radially inward. A second coupling member (26) positioned between the blade and outer bearing ring extends radially inward and over the inner bearing ring. A drive system (28) includes a first drive member (34) coupled to the first coupling member and a first driven member (36) coupled to the second coupling member. The first drive member is configured to move the first driven member to rotate the outer bearing ring relative to the inner bearing ring and thereby pitch the blade.

Abstract: A wind turbine is described which comprises a tower, a nacelle mounted to the top of the tower, and a rotor mounted to the nacelle. The rotor comprises two or more blades mounted to a central hub. The hub supports two or more annular pitch bearings associated respectively with the two or more blades. Each pitch bearing defines a bearing plane inclined at a first angle with respect to a horizontal plane when the respective blade is oriented in a downwardly direction in alignment with the tower. Each pitch bearing is spanned by a hub plate; and a work platform integral with or mounted to the hub plate lies generally in a plane at a second angle to the horizontal plane when the respective blade is oriented in a downwardly direction in alignment with the tower, which second angle is less than the first angle. The work platform provides a substantially horizontal platform for use by maintenance personnel when installing or servicing components in and around the hub.

Abstract: A method of starting up a wind turbine includes heating first and second components, the first component having a first minimum operating temperature and the second component having a second minimum operating temperature. Excess heat is generated after the second component has been heated to the second minimum operating temperature. The excess heat is transferred to the first component to assist heating the first component to the first minimum operating temperature. The first and second components are cooled after reaching the first and second minimum operating temperatures.

Abstract: A wind turbine (1) comprising a nacelle, a hub (4), a rotating shaft (14) arranged to be connected to a generator (12) in order to transfer rotational movement to the generator (12), and a gear arrangement (7). The gear arrangement (7) comprises a number of pulleys (8, 9, 11) and a number of belts (15, 16) interconnecting the pulleys (8, 9, 11) in order to transfer rotational movements between the pulleys (8, 9, 11), thereby transferring rotational movements from the hub (4) to the rotating shaft (14). The hub (4) is arranged between the gear arrangement (7) and the nacelle in order to allow easy replacement of the belts (15, 16) of the gear arrangement (7).

Abstract: The present invention relates to a rope-driven transmission for a wind turbine. The transmission comprises an input rotary member for being operatively connected to a rotor of a wind turbine and in rotational connection with at least one secondary shaft which is arranged in parallel with the rotational axis of said input rotary member, wherein said secondary shaft is adapted for operative connection with an output member of at least one electrical generator, wherein said rotational connection between said input rotary member and said at least one secondary shaft is provided by a rope, the course of said rope defining a rope path, and wherein said rope path includes a plurality of turns around said input rotary member and said secondary shaft. The transmission facilitates an easy monitoring and maintenance of the transmission. The invention further relates to a method of maintaining the transmission by replacing the rope. The invention further relates to a wind turbine generator comprising the transmission.

Abstract: A blade bearing for mounting a blade of a wind turbine to a hub of the wind turbine comprises inner and outer rings arranged next to each other. One of the inner and outer rings is configured to mount to the blade, and the other is configured to mount to the hub. At least two rows of rolling elements are positioned between the inner and outer rings. Upper and lower rows of the rolling elements are located in respective upper and lower planes. A support structure is secured to the inner ring and extends in a substantially radial direction between the upper and lower planes. The support structure has non-uniform stiffness characteristics in a circumferential direction. A method of manufacturing a blade bearing is also provided.

Abstract: The invention provides a wind turbine comprising a nacelle, a rotor comprising at least one blade attached to a hub, and an electrical supply structure for supplying electrical power from the nacelle to the rotor. The rotor is rotatably connected to the nacelle about an axis of rotation. The supply structure comprises a switch which has a connected mode in which the nacelle and the rotor are electrically connected, and a disconnected mode in which the nacelle and the rotor are electrically disconnected. Furthermore, the switch is adapted to change from the disconnected mode to the connected mode when the rotor does not rotate.

Abstract: A blade bearing for mounting a blade of a wind turbine to a hub of the wind turbine comprises inner and outer rings arranged next to each other. One of the inner and outer rings is configured to mount to the blade, and the other is configured to mount to the hub. At least two rows of rolling elements are positioned between the inner and outer rings. Upper and lower rows of the rolling elements are located in respective upper and lower planes. A support structure is secured to the inner ring and extends in a substantially radial direction between the upper and lower planes. The support structure has non-uniform stiffness characteristics in a circumferential direction. A method of manufacturing a blade bearing is also provided.

Abstract: The present invention relates to a hydraulic pitch system for pitching a blade of a wind turbine having a hub by means of a hydraulic fluid. The system comprises at least one hydraulic cylinder for adjusting a pitch angle of the blade, the hydraulic cylinder comprising a pitch piston movable in the hydraulic cylinder, and a first port and a second port arranged on each side of the pitch piston, and an accumulator hydraulically connected to the cylinder. The system further comprises a pitch safety system adapted to maintain the blade in a predetermined pitch angle when a person is entering the hub of the wind turbine for service and/or maintenance, the pitch safety system comprising a first valve which by activation releases a pressure in the hydraulic pitch system by draining off the accumulator for the hydraulic fluid until the pressure has reached a predetermined pressure level.