Showing papers by "Vestas published in 2003"

A dynamic voltage restorer (DVR) with selective harmonic compensation at medium voltage level

Abstract: Dynamic voltage restorers (DVRs) are now becoming more established in industry to reduce the impact of voltage sags to sensitive loads. However, DVRs spend most of their time in standby mode, since voltage sags occur very infrequently, and hence their utilization is low. In principle, it would be advantageous if the series-connected inverter of a DVR could also be used to compensate for any steady-state load voltage harmonics, since this would increase the power quality "value-added" benefits to the grid system. However, before this can be done, consideration must be given to the control of steady-state power through the DVR, the increased losses, and the low modulation depths at which the scheme must operate to achieve acceptable harmonic compensation performance. This paper presents a selective harmonic feedback control strategy that can be easily added to medium-voltage DVR systems to provide voltage harmonic compensation capabilities with minimal effect on the sag compensation performance of the basic DVR. The proposed controller has been experimentally verified on a medium-voltage (10 kV) three-phase DVR prototype under a range of conditions, including distorted supply voltages, nonlinear loads, and operation during distorted voltage sags.

Wind turbine with floating foundation

Abstract: A floating foundation for wind turbines is disclosed, where the foundation essentially comprises at least three submerged buoyancy bodies connected to the lower end of the tower of the wind turbine at a common node member situated well above the surface of the sea. The buoyancy bodies are connected to the node member by means of relatively thin leg sections, whereby wave load on the foundation is reduced. By applying the foundation according to the present invention, stress concentrations and torques in the node member are reduced, whereby it becomes possible to apply a relatively lightweight and hence cheap node member. The overall weight of the construction is thereby reduced and hence the volume of the buoyancy bodies necessary to counteract the overall weight of the construction.

Method of manufacturing a wind turbine blade, wind turbine blade, front cover and use of a front cover

Abstract: The invention relates to a method of manufacturing a wind turbine blade, said method comprising the steps of: casting at least two wind turbine shells and preferably one or more load bearing structures, forming a wind turbine blade structure including at least two longitudinal joints by adhering said at least two wind turbine shells and said one or more load bearing structures together, forming one or more front covers to a shape substantially corresponding to said wind turbine blade structure or sections hereof, positioning said one or more front covers in relation to said wind turbine blade structure, and fastening said one or more front covers to said wind turbine blade structure with adhering means. The invention also relates to a wind turbine blade, front cover and the use of a front cover as a unit for supplementary mounting on a wind turbine blade.

Method of controlling a wind turbine connected to an electric utility grid during malfunction in said electric utility grid, control system, wind turbine and family hereof

Abstract: The invention relates to a method of controlling a wind turbine connected to an electric utility grid during malfunction in said electric utility grid, said method comprising the steps of detecting a malfunction in said electric utility grid and monitoring at least one physical work property of at least one component of said wind turbine. Further, the method controls the pitch of one or more win turbine blades of said wind turbine in order too keep said least one physical work property below at least one predefined limit in a time period of said malfunction. The invention also relates to a control system for a wind turbine connected and supplying electric power to a utility grid as well as a wind turbine and park hereof.

Method of constructing large towers for wind turbines

Abstract: In order to transport large size windmill towers, the invention suggests a steel tower ( 1 ) for a windmill, comprising a number of cylindrical or tapered tower sections ( 2 ), at least the wider sections ( 2 ) of which being subdivided into two or more elongated shell segments ( 3 ), which combine into a complete tower section ( 2 ) by means of vertical flanges ( 6 ) tightened together, e.g., by bolts ( 10 ), said shells being also provided with upper and lower horizontal flanges ( 4 ), respectively, to allow interconnection of tower sections ( 2 ) one on top of the other.

Method of servicing the outer components of a wind turbine such as the wind turbine blades and the tower with a work platform and work platform

Abstract: The invention relates to a method of servicing the outer components of a wind turbine such as the wind turbine blades and the tower with a work platform, said method comprises the steps of: positioning the work platform at the wind turbine tower and connecting the work platform to an upper part of the wind turbine with at least one cable. Further the method comprises the steps of raising the work platform with the cable and cable winding means to a position of use, and holding the work platform to the side of the wind turbine tower with holding means. The invention also relates to a work platform for servicing the outer components of a wind turbine.

Member for potential equalising

Abstract: A member for potential equalising in a wind turbine blade between a first conducting member, such as a member comprising carbon fibres, and a second conducting member, such as a lightning conductor is provided. Furthermore, methods for manufacturing of such members for potential equalising are provided.The member for potential equalising comprises a first contact part suitable for connection to a conducting member comprising carbon fibres, a second contact part and an electrical conductor between the contact parts and the first contact part, wherein the first contact part is shaped substantially as a ribbon.

Method for controlling a power-grid connected wind turbine generator during grid faults and apparatus for implementing said method

Abstract: The present invention relates to a method and an apparatus for controlling a power-grid connected wind turbine generator during grid faults. During grid faults, the stator windings of the wind turbine generator are disconnected from the power grid and impedances for dissipating at least part of the power generated by the wind turbine during grid fault condition are connected to the stator windings. In this way, a certain magnetisation of the generator can be maintained and after removal of the grid fault condition, the generator is synchronised to the power grid and the impedances are disconnected and the stator windings are reconnected to the power grid. In this way, it is possible to keep the wind turbine generator at least partly magnetised during grid faults and thus ready for delivering power to the power grid, as soon as the grid voltage is re-established after the fault.

Pre-form and method of preparing a pre-form

Abstract: A pre-form and a method of preparing pre-forms are provided. The pre-forms comprise a resin and at least two layers of oriented fibre tows. The pre-forms comprise fibre tows instead of the traditional prepregs to enhance rearranging of resin and/or fibres during subsequent processing as well as provide greater freedom, a price reduction and/or a reduction of waste. The pre-forms may be formed three-dimensionally to enhance coupling to further pre-forms or other structures and/or to enhance shaping of the pre-form to a final three-dimensional shape. The method of preparation of pre-forms involves providing an adhesive between layers of fibres and providing a resin in contact with at least one of the layers of fibres. The resin is preferably provided in a non-continuous layer to allow for removal of gas at least partially in a direction orthogonal to the layers of resin. The pre-forms are suitable for preparation of composite structures like for example spars for wind turbine blades.

Circuit to be used in a wind power plant

Abstract: The invention relates to a circuit with a variable rotational speed to be used particularly in a wind power plant, comprising a double fed asynchronous generator (DASM), a crow-bar, an additional resistor (R15) and a converter. In order to meet the requirements of the network provider, whereby a particularly permanent coupling to the network should be ensured so that the wind power plant can start up and stabilize the network during and after medium voltage short circuit in the network, the additional resistor can be regulated with the aid of a fast switch in such a way that the converter can be provisionally disconnected at least partly in case of a short circuit in the network. The rotor current is momentarily assumed by the additional resistor and disconnected after the rotor short circuit current dies out so that the converter can be subsequently connected once again and so that it can supply the desired active short circuit current to the network.

Wind turbine, lightning connection means, method and use hereof

Abstract: The invention relates to a wind turbine (1) comprising stationary means such as a nacelle (3) and a tower (2) comprising stationary lightning protection means (46), and rotating means such as a rotor including at least one wind turbine blade (5) and shaft means (14), each of said at least one wind turbine blade (5) comprising rotating lightning protection means (47). The stationary and rotating lightning protection means (46, 47) comprise contact surfaces (17, 18) connected by lightning connection means (15). The lightning connection means (15) comprises at least two contact means (19, 19a, 19b) adapted for connecting said rotating and stationary lightning protection means (46, 47). Further, it comprises at least one electric conductor (30) establishing a dedicated connection between said at least two contact means (19, 19a, 19b) and force transferring means (26, 27) for said at least two contact means (19, 19a, 19b) establishing a continuous connection between said at least two contact means (19, 19a, 19b) and the contact surfaces (17, 18) of said stationary and rotating lightning protection means (46, 47). The invention also relates to lightning connection means (15) for a wind turbine (1), a method and use hereof.

Wind turbine blade, wind turbine, method of providing lightning receptor means to a wind turbine blade and use hereof

Abstract: The invention relates to a wind turbine blade comprising lightning protection means. At least one section of the tip of said blade is made in solid metal and is included as part of said lightning protection means. The invention also relates to a wind turbine, a method of providing lightning receptor means to a wind turbine blade and use hereof.

Circuit arrangement and methods for use in a wind energy installation

Abstract: The invention relates to a circuit with a variable rotational speed to be used particularly in a wind power plant, comprising a double fed asynchronous generator (DASM), a crow-bar, an additional resistor (R 15 ) and a converter. In order to meet the requirements of the network provider, whereby a particularly permanent coupling to the network should be ensured so that the wind power plant can start up and stabilize the network during and after medium voltage short circuit in the network, the additional resistor can be regulated with the aid of a fast switch in such a way that the converter can be provisionally disconnected at least partly in case of a short circuit in the network. The rotor current is momentarily assumed by the additional resistor and disconnected after the rotor short circuit current dies out so that the converter can be subsequently connected once again and so that it can supply the desired active short circuit current to the network.

Transportation system for a wind turbine component, vehicle for a transportation system, displacement system, method of establishing a transportation or displacement and use thereof

Abstract: The invention relates to a transportation system for a wind turbine component such as a wind turbine nacelle or a section of a tubular wind turbine tower, said system comprising a wind turbine component with a rigid structure. The system further comprises at least one standardization means directly or indirectly connected to the rigid structure (6) of said wind turbine component (3), where said at least one standardization means defines a space enclosing said component. The invention also relates to a vehicle for a transportation system, a displacement system and a method of establishing a transportation or displacement system for a wind turbine component.

Methods of moving the rotating means of a wind turbine during transportation or stand still, method of controlling the moving of the rotating means, nacelle, auxiliary device, control and monitoring system and use hereof

Abstract: The invention relates to methods of moving the rotating means of a wind turbine during transportation or stand still. The methods may comprise the steps of: securing at least one auxiliary device to a position and connecting said device to one or more shafts of the rotating means at the transportation or stand still. The auxiliary device being able to store, generate and/or convert energy during transportation, transferring energy continuously from said at least one auxiliary device to said one or more shafts of the rotating means during transportation or stand still, and moving said one or more shafts of the rotating means continuously or discontinuously from a position to another. The invention also relates to a nacelle for a wind turbine, an auxiliary device, a control system for controlling the moving of the rotating means of a wind turbine nacelle during transportation of the nacelle and use hereof.

Connection between members

Abstract: A method for preparing a more reliable connection between two members (2, 4) is provided. The method involves the use of a gas-removal layer (6), which allows for gas transport in a number of overall directions in a plane of the gas-removal layer. The gas-removal layer comprises a resin (12) and during consolidation the gas-removal layer is deformed to form a collection substantially free from entrapped gas voids. Furthermore, a gas-removal layer is provided as well as a mould for casting of gas-removal layers and a method for preparing such a mould.The method and the gas-removal layer provided are particularly useful for manufacturing of wind turbine blades and spars for such blades.

Method of moving the rotating means of a wind turbine during transportation or stand still, nacelle, auxiliary device, and use thereof

Abstract: The invention relates to methods of moving the rotating means of a wind turbine during transportation or stand still. The methods may comprise the steps of: securing at least one auxiliary device to a position and connecting said device to one or more shafts of the rotating means at the transportation or stand still. The auxiliary device being able to store, generate and/or convert energy during transportation, transferring energy continuously from said at least one auxiliary device to said one or more shafts of the rotating means during transportation or stand still, and moving said one or more shafts of the rotating means continuously or discontinuously from a position to another. The invention also relates to a nacelle for a wind turbine, an auxiliary device, a control system for controlling the moving of the rotating means of a wind turbine nacelle during transportation of the nacelle and use hereof.

Switching device for a wind power plant

Abstract: The arrangement has a dual supply asynchronous motor, an auxiliary resistance and a converter. The resistance is regulated with a switch so the converter can be at least partly temporarily switched off in the event of a short circuit to temporarily take up the rotor current with the auxiliary resistance and to be switched on again after rotor short circuit current decay to actively couple a short circuit current into the supply.

Method of mounting elements in a wind turbine tower, wind tower suspension unit, system of mutually attachable members

Abstract: The invention relates to a method of mounting elements in a wind turbine tower (10, 11, 12, 13, 14) whereby said elements are partly or completely attached to the wind turbine tower (10, 11, 12, 13, 14) by means of magnetic attraction forces. According to the invention, wind turbine suspension units may be attached to the wind turbine tower, preferably completely or partly to the inner wall by means of magnetic attraction forces, which prevent structure-weakening attachments to the tower or part of the tower.

Method of preparing a preform

Abstract: A pre-form and a method of preparing pre-forms are provided. The pre-forms comprise a resin and at least two layers of oriented fibre tows. The pre-forms comprise fibre tows instead of the traditional prepregs to enhance rearranging of resin and/or fibres during subsequent processing as well as provide greater freedom, a price reduction and/or a reduction of waste. The pre-forms may be formed three-dimensionally to enhance coupling to further pre-forms or other structures and/or to enhance shaping of the pre-form to a final three-dimensional shape. The method of preparation of pre-forms involves providing an adhesive between layers of fibres and providing a resin in contact with at least one of the layers of fibres. The resin is preferably provided in a non-continuous layer to allow for removal of gas at least partially in a direction orthogonal to the layers of resin. The pre-forms are suitable for preparation of composite structures like for example spars for wind turbine blades.

Lightning protection system for a wind turbine, method and use thereof

Abstract: System lightning protection including connection means arrester (15) for a wind turbine (1), said system protection rotating and fixed beams (46, 47) of said wind turbine characterized in that the system further comprises comprising at least two contact means (19, 19a, 19b) adapted for connection protection means rotating and fixed beams (46, 47) of said at least one electrical conductor (30) wind turbine which provides a dedicated connection between said at least two contact means (19, 19a, 19b), and transfer means of force (26, 27) which provide a continuous connection between said at least two contact means (19, 19a, 19b) and surfaces contact (17, 18) of said protection means fixed and rotating beams (46, 47).

Transportation system for a wind turbine component and method for transporting a wind turbine component

Abstract: The invention relates to a transportation system for a wind turbine component such as a wind turbine nacelle or a section of a tubular wind turbine tower, said system comprising a wind turbine component with a rigid structure. The system further comprises at least one standardization means directly or indirectly connected to the rigid structure (6) of said wind turbine component (3), where said at least one standardization means defines a space enclosing said component. The invention also relates to a vehicle for a transportation system, a displacement system and a method of establishing a transportation or displacement system for a wind turbine component.