Abstract:
It is described a method for controlling the rotational speed of a rotor of a wind turbine in particular at high wind speeds. The described method comprises (a) determining a rotor acceleration value, wherein the rotor acceleration value is caused by a temporal change of the rotational speed of the rotor, and (b) controlling the rotational speed of the rotor as a function of the rotor acceleration value. It is further described a control system for controlling the rotational speed of a rotor of a wind turbine, a wind turbine being equipped with such a control system and to a computer program, which is adapted for controlling and/or for carrying out the mentioned rotational speed control method.
Abstract:
It is described a stator for an energy converting apparatus, the stator comprising the stator including a support structure having an annular shape around an axial direction; a first protrusion coupled to the support structure and extending radially from the support structure; a second protrusion coupled to the support structure and extending radially from the support structure, the second protrusion being spaced apart from the first protrusion in a circumferential direction; and a first wire arranged between the first protrusion and the second protrusion in a plurality of first radial layers located at different radial positions and configured such that a circumferential extent of a cross-sectional area of the first wire increases radially outwards. Further is described an energy converting apparatus including the stator, and a wind turbine including the energy converging apparatus.
Abstract:
A method and a wind power plant are provided for smoothing alternating electric current from a number of power generators. Generators are electrically connected to an electric network. Each power generator includes a transformer with pulse width modulation for converting direct current to pulse width modulated alternating current for feeding to the network. The time for feeding the pulses of the pulse width modulated alternating current is different for each generator in order to achieve a more even alternating current as a sum of respective outputs of alternating current from the generators.
Abstract:
A mold and method for vacuum assisted resin transfer molding of a fiber reinforced laminated structure are provided. The mold includes a first mold part and a second mold part. The first mold part defines a negative impression of the laminated structure, being structurally stable and forming a support for fiber reinforcement layers of the laminated structure. The second mold part connectable to the first mold part for closing the mold and defines together with the first mold part an enclosed space which can be evacuated. The mold further includes a flow duct for guiding a liquid polymer which is formed as a recess in the first mold part and/or a recess in the second mold part that is open towards the enclosed space and extends along a section of the periphery of the first mold part and/or the second mold part.
Abstract:
Method and connecting piece for assembling a first and a second arm section in extension of one another in order thus to form at least a part of an arm, preferably a windmill arm, where two arm sections are connected to at least one connecting piece for mounting between the two arm sections. The connecting piece is provided with a first flange for attachment to the end of the first arm section and a second flange for attachment to the end of the second arm section, the first and the second flange being firmly interconnected. The first and the second flange are each provided with at least one hole for a bolt which extends through the hole from the connecting piece and into the adjacent arm section, this bolt or these bolts securing each arm section to the adjacent flange.
Abstract:
An arrangement to set up and to ensure an air gap in an electrical machine, like a generator, is provided. The electrical machine includes a stator arrangement and a rotor arrangement. The rotor-arrangement rotates around a longitudinal axis. At least parts of the rotor arrangement interact with parts of the stator arrangement to generate electrical power. An air gap is defined by the distance between the parts of the rotor arrangement and the parts of the stator arrangement. The parts of the stator arrangement are opposite to the parts of the rotor arrangement along a certain length. The cross-section of the air gap changes along the certain length, so that the air gap is not uniform in view to the referred certain length.
Abstract:
A concrete tower is provided. The concrete tower may be a concrete tower for a wind turbine. The compressive strength of the concrete is changed in dependency of the height of the tower. The concrete tower includes a number of tendons that are arranged to pre-stress the concrete tower. Each tendon is anchored with the concrete tower at a first end of the tendon and at a second end of the tendon.
Abstract:
A number of pre-casted elements are stacked vertically to build the tower, while parts of the elements are forming the tower wall. Each element of the tower is fixed on its position and is connected with a tower foundation by a number of assigned post-tensioned cables. These cables are running inside the tower and they are pulled through the tower without embedding in dedicated channels. The post-tensioned-cables are fixed at certain points with the tower wall via damper-means to prevent their oscillation.
Abstract:
A method of controlling a temperature of a component of a wind turbine is disclosed. A set point temperature of the component is defined. The actual temperature of the component is determined and compared with the defined set point temperature. The actual temperature of the component is controlled by controlling the output power of the wind turbine based on the result of comparison.