A scroll compressor includes a balancer that rotates integrally with a rotary shaft. A bushing includes a cylindrical portion and an auxiliary weight portion. The auxiliary weight portion is arranged on the outer side of the cylindrical portion. The fitting hole is provided at a position where a moment about the eccentric shaft generated by a centrifugal force acting on the movable scroll due to rotation of the rotary shaft and a moment about the eccentric shaft generated by a centrifugal force acting on the auxiliary weight portion due to rotation of the rotary shaft are in the opposite directions. As viewed in the axial direction of the rotary shaft, the center of gravity of the bushing is located on the same side of a straight line including the center of the cylindrical portion and the center of the rotary shaft as the center of the eccentric shaft.

An impeller that rotates about a central axis extending vertically includes a base portion and blades. The base portion spreads perpendicularly to the central axis. The blades are on an upper surface of the base portion at intervals in a circumferential direction. The base portion includes an irregular portion that is radially outward and in which irregularities are repeated in the circumferential direction. The irregular portion includes one or more first irregular regions and a second irregular region. The first irregular regions include first recesses with a same shape and first projections with a same shape, the first recesses and projections being alternately arranged one by one. The second irregular region is positioned between the first irregular regions and includes at least one among a second recess with a different shape from the first recesses and a second projection with a different shape from the first projections.

The present invention relates to a wind turbine and a method of operating a wind turbine for reducing edgewise vibrations, wherein the wind turbine comprises a wind turbine control system having at least one vibration sensor for measuring the edgewise vibrations and a controller for receiving the vibration signal from the vibration sensor. The sensor unit is preferably an accelerometer arranged in a stationary frame of reference. The controller determines at least one whirling mode frequency and the vibration level thereof. The controller initiates a corrective action if the measured vibration level exceeds a threshold value. The corrective action is preferably an adjustment of the pitch angle of the wind turbine blades which in turn dampens the edgewise vibrations.

A pitch control system characterized by a hub with at least two blade housings on the hub that are disposed around the hub axis. The blade housings have corresponding blades that engage with them. The blades spiral along housing longitudinal axes toward and away from the hub axis about a segment of helical path to effect a change in the pitch of each blade. One or more elastic members draw the blades toward the hub axis, either directly or indirectly. There are pitch mechanisms effective to facilitate blades to spiral around housing-longitudinal axes. A blade will spiral away from the hub axis when the centrifugal force exerted on the blade exceeds the opposing elastic force in the housing-longitudinal direction (neglecting other forces). Conversely, blades spiral toward the hub axis when said centrifugal force is less than said elastic force. There is an imaginary plane orthogonal to the hub axis. Housing-longitudinal axes have angles with respect to the imaginary plane of not more than 30 degrees.

The present invention relates to a method of controlling a wind turbine comprising a tower supporting a rotor comprising a plurality of pitch-adjustable rotor blades. The method includes obtaining a movement signal indicative of a lateral movement of the tower; determining a pitch modulation signal, based on the movement signal, for actuating a rotor blade to produce a desired horizontal force component to counteract the lateral movement of the tower; determining a radial force component acting on a rotor blade; determining a phase offset parameter for the rotor blade based on the radial force component; and, transforming the pitch modulation signal into a pitch reference offset signal for the rotor blade based on the phase offset parameter.

There is disclosed a method of balancing a set of first and second modular blade sections for a set of blades of a rotor of a wind turbine. The method comprises determining a mass moment of the first and second blade sections, the mass moment being deter-mined about an axis equivalent to an axis of rotation of a hub of the turbine when the blade section is assembled onto the hub. A plurality of blade section groups 10 are defined, each comprising a first blade section of the set and at least one second blade section of the set, each blade section group having a blade section group mass moment about the axis. The first blade section and the at least one second blade section in each group are selected so as to satisfy a minimised total ballast condition, to minimise balancing ballast to be added to the set as a whole, or a minimised 15 ballasting difference condition, to minimise the difference in balancing ballast added to different blades, or both.

A method for calculating axis deviation of rotor assembly based on end face runout measurement comprises three parts: calculation of three contact points, a triangle judgment criterion and a homogeneous coordinate transformation algorithm of a deviation matrix. Based on the measured end face runout data in production practice, the method realizes the prediction of axis deviation before assembly, improves the concentricity of rotors after assembly, also greatly increases the one-time acceptance rate of assembly and has important practical guiding significance for axis prediction as well as assembly phase adjustment and optimization in the assembly process of aero-engine rotor pieces.

A method for wind turbine tower damping is disclosed, as well as an associated controller and wind turbine. The method comprises generating, using at least a first sensor signal, a first pitch reference signal for one or more rotor blades of a wind turbine during partial load operation. The method further comprises determining, using at least a second sensor signal, dynamic state information for a tower of the wind turbine. The method further comprises generating a second pitch reference signal by adapting the first pitch reference signal using the dynamic state information. The method further comprises selecting a maximum pitch reference signal from the second pitch reference signal and a saturation pitch reference signal. The method further comprises communicating the maximum pitch reference signal to control a pitch of the one or more rotor blades.

A method for wind turbine tower damping is disclosed, as well as an associated controller and wind turbine. The method comprises determining, using one or more sensor signals, dynamic state information for a tower of a wind turbine during power production, wherein the dynamic state information comprises a tower frequency. The method further comprises determining at least one control loop gain value using the tower frequency, and generating, using the at least one control loop gain value, one or more control signals for controlling a rotational speed of a rotor of the wind turbine.

The present invention includes a rotor-blade span-balancing system, including a span-balance pocket in a surface of a rotor blade; a cover operably configured to cover the span-balance pocket, wherein the cover is operably configured to be substantially flush with the surface of the rotor blade surface when covering the span-balance pocket, and wherein the cover includes a cover boss for reacting centrifugal force of the cover into the rotor blade; and one or more span-balance weights attached to the cover to span-balance the rotor blade.