A method of operating a wind turbine during a service, wherein the wind turbine comprises at least one rotor-nacelle assembly, the or each rotor-nacelle assembly comprising a rotor; the method comprising: detecting that a service is to be or is being carried out on the wind turbine; and, on detecting that a service is to be or is being carried out on the wind turbine, reducing an operating level of the or each rotor-nacelle assembly.

The Variable Tilting Blade Twin Turbine Wind Mill device is for capturing kinetic energy from the wind and is comprised of a shaft having a plurality of central hubs connectively attached, each central hub having a plurality of wind capture arms comprising a rotating wind capture blade having a capture surface and a slicing edge that are rotated by a rotating gear and drive gear combination connectively attached to said wind capture blades enabling a rotation of said wind capture blades wherein the wind capture blades are rotated between a blade-mode to capture the wind and a knife-mode to pass with less drag resistance through the air/wind thereby enabling an increase in the ability to capture more of the energy available in the wind stream.

A method of operating a wind turbine during a service, wherein the wind turbine comprises at least one rotor-nacelle assembly, the or each rotor-nacelle assembly comprising a rotor; the method comprising: detecting that a service is to be or is being carried out on the wind turbine; and, on detecting that a service is to be or is being carried out on the wind turbine, reducing an operating level of the or each rotor-nacelle assembly.

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 multirotor wind turbine (1) with a tower (2) and at least two energy generating units, the units held by a load carrying structure (9, 10) extending transverse to the vertical direction of the tower. To enable improved access to the wind turbine, a platform (12) forming an upwards facing plane working surface (17) is provided.

A method of damping oscillations in a multi-rotor wind turbine and a wind turbine are provided. The wind turbine comprises a wind turbine support structure and at least a first nacelle with a first rotor and a second nacelle with a second rotor, at least one of the nacelles being located at a position away from a central longitudinal axis of the wind turbine support structure. The method comprises the steps of receiving and processing motion data, selecting a damping algorithm and generating a pitch control signal. The processing comprises determining at least one prominent oscillation mode of the wind turbine support structure and selecting a corresponding damping algorithm.

The present invention is directed to operation of a multi-rotor wind turbine comprising at least two rotors. Each rotor has a rated capacity. The method comprises monitoring a power output of the rotors, detecting that the power output of at least a first one of the rotors is below its rated capacity, detecting that the power output of at least a second one of the rotors is at its rated capacity, and controlling operation of the second rotor, such as to temporarily increase its power output to a value above its rated capacity.

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 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.