A method and a device for dampening movement in a multiple rotor (MR) wind turbine located at sea and comprising a tower (2) extending in an upwards direction, a load carrying structure (3, 4) forming a first section (3) and a second section (4), the first and second sections extending in different directions away from the tower (2). To provide efficient dampening of the movement, the method comprises tethering a first body (20) to the first section (3), the first body being at least partly submerged into the sea.

A system with a first turbine rotating in a first direction and a second turbine rotating in a second direction, wherein there is negative clearance associated with blades of the first turbine and the blades of the second turbine.

A multi-stage wind power extractor includes a tunnel and at least two turbines. The tunnel is circular in a cross-section and has a horizontal axis, first and second open ends, and a length that is greater than a diameter of the tunnel. The tunnel diameter progressively increases from the first open end to the second open end. The turbines are arranged in spaced relation within and coaxial with the tunnel. Each includes a rotor having a plurality of radially extending blades, a controller connected with the rotor, and a motor connected with the controller. The controllers independently engage and disengage their respective rotors in accordance with a wind velocity travelling through the tunnel from the first open end to the second. In turn, when a rotor is engaged, the motor provides power to a generator that is connected therewith.

A wind energy harvesting machine with three counter-rotating rotors in a duct is disclosed. The wind energy harvesting machine includes a tower, a duct, a counter-rotating generator with two rotary parts, and three groups of blades. The duct includes supporting static stators in front and rear and a static nose cone in the front. The counter-rotating generator has a main shaft and rotary interior and exterior parts to rotating in opposite directions. Three rotary blade groups including front and rear blade groups rotatable around the main shaft in the same direction, and a middle blade group rotatable in an opposite direction. The front and rear blade groups are displaceable axially along the main shaft and the middle blade group is fixed on the exterior part of the counter-rotating generator.

A vertical axis turbine having a first rotor and at least one second rotor, the first rotor being configured to rotate around a first rotation axis that is vertical or more vertical than horizontal, in use. The first rotor may be configured to be driven and/or rotated by fluid motion, e.g. by wind or water flow. The at least one second rotor is provided on or coupled to the first rotor such that the first rotor is operable to move the second rotor through the fluid and thereby drive the second rotor upon rotation of the first rotor. The second rotor is operable to drive a power take off system. Optionally, rotation of the first rotor around the first rotation axis moves the second rotor around the first rotation axis. Each second rotor rotates around a respective second rotation axis that may be angled or perpendicular to the first rotation axis of the first rotor and is optionally a horizontal axis or at least an axis that is more horizontal than vertical, in use. The first and second rotors are configured so that the power take-off is by direct drive without the need for a gearbox or multi-pole generator. The first and second rotors are configured so that the power conversion of mechanical power at the first rotor is converted to mechanical power at the second rotors has high efficiency.

A multirotor wind turbine comprising a tower, a suspension arm, a nacelle, and a rotor carried by the nacelle and configured to rotate about a rotor axis to drive a drive train in the nacelle, wherein the tower holds the suspension arm, and the suspension arm holds the nacelle. To facilitate safer and better access to the nacelle or drive train, the suspension arm is configured as a platform to provide support for personnel e.g. during maintenance and repair of the nacelle.

A wind turbine comprising a frame on a floating pontoon, wherein the frame is constructed as a lattice rig upright on the pontoon forming a plurality of rectangular or square openings in the rig for receiving respective interchangeable wind turbine generators with associated drive propellers driven by incoming wind, and each wind turbine generator being arranged to travel up the rear of the rig and through the openings towards the front of the rig. The wind power plant is characterized in that each turbine generator comprises one or more pairs of propeller blades forming a propeller set having a blade diameter defining the turbine rotational plane, each propeller set is arranged at a distance from the front side of the rig to be rotated by the incoming wind towards the rig. There is also described a method for mounting turbines with associated propeller sets and openings in the rig, respectively.

The invention relates to a method for monitoring performance of a multi-rotor wind turbine. According to the method parameter for each of the wind turbine modules of the multi-rotor wind turbine is obtained. The parameters of each of the wind turbine modules are compared, e.g. by means of a comparison parameter determined from the individual parameters. Dependent on the result of the comparison, a performance action is initiated, e.g. for the purpose of further characterization or verification of a deviating parameter determined via the comparison.

A multirotor wind turbine (1) comprising a tower structure (2) and at least one load carrying structure (3), each load carrying structure (3) being arranged to carry two or more energy generating units (5), is disclosed. The wind turbine (1) further comprises a yawing arrangement (6) comprising a first part (9) being fixedly connected to the tower structure (2) and a second part (10) being fixedly connected to at least one of the load carrying structure(s) (3). The first part (9) and the second part (10) are configured to perform rotating movements relative to each other, thereby allowing the load carrying structure (3) to perform yawing movements relative to the tower structure (2). At least one guy wire (7) is connected between an anchoring point (8) at the ground and the first part (9) of the yawing arrangement (6). The invention further provides a yawing arrangement (6) for such a multirotor wind turbine (1).

A system with a first turbine rotating in a first direction and a second turbine rotating in a second direction, wherein there is negative clearance associated with blades of the first turbine and the blades of the second turbine.