Showing papers by "Vestas published in 2009"

Variable speed wind turbines capability for temporary over-production

Abstract: New control systems for Variable Speed Wind Turbines (VSWT) need to be developed in order to provide inertia response and frequency control to support the grid. This work studies the behavior and capability of VSWT for providing temporary active power overproduction. The study is conducted on a multi-megawatt VSWT with Doubly-Fed Induction Generator. It was found that it is possible to have an active power overproduction of 0.2 pu for at least 10 seconds, which could be useful for the grid operator for restoring a critical situation of grid frequency dip. Nevertheless it is important to be aware about the underproduction power and the associated recovery period that follow a VSWT overproduction operation. The results can be used in designing suitable control systems for VSWT inertia response and frequency control.

Linear parameter varying control of wind turbines covering both partial load and full load conditions

Abstract: This paper considers the design of linear parameter varying (LPV) controllers for wind turbines in order to obtain a multivariable control law that covers the entire nominal operating trajectory. The paper first presents a controller structure for selecting a proper operating trajectory as a function of estimated wind speed. The dynamic control law is based on LPV controller synthesis with general parameter dependency by gridding the parameter space. The controller construction can, for medium- to large-scale systems, be difficult from a numerical point of view, because the involved matrix operations tend to be ill-conditioned. The paper proposes a controller construction algorithm together with various remedies for improving the numerical conditioning the algorithm. The proposed algorithm is applied to the design of a LPV controller for wind turbines, and a comparison is made with a controller designed using classical techniques to conclude that an improvement in performance is obtained for the entire operating envelope. Copyright © 2008 John Wiley & Sons, Ltd.

Maximizing Wind Turbine Energy Capture using Multivariable Extremum Seeking Control

Abstract: Maximizing energy capture has become an important issue as more turbines are installed in low wind areas. This paper investigates the application of extremum seeking control (ESC) to maximizing the energy capture of variable speed wind turbines. The optimal control torque and pitch angle are searched via ESC based on the measurement of the rotor power. The advantage of this method is the independency from accurate turbine modelling and wind measurement. Simulation was conducted on FAST for a wind turbine dynamic model, under smooth, turbulent and field recorded wind profiles. The simulation results demonstrated significant improvement in energy capture compared to the standard control with fixed reference. An anti-windup ESC was applied to overcome the integral windup due to actuator saturation which would otherwise disable the ESC process. Finally, the integrator and high-pass filter resetting schemes were applied to improve the transient under the abrupt changes of wind.

Chopper controlled resistors in VSC-HVDC transmission for WPP with full-scale converters

Abstract: Large and distant offshore wind power plants can be efficiently connected to the onshore power grid network using VSC-HVDC (Voltage Source Converter based HVDC) transmission Chopper controlled resistors can be used to limit the DC line over-voltage when there is a fault on the onshore AC grid and power transfer to the grid is obstructed Considering the development of full scale converter based wind turbine generators (WTG), use of unit rated chopper controlled resistors for each of the full scale AC-DC-AC converter system of the individual turbines has been proposed in place of the one on the HVDC line side Both the cases have been simulated and their performances are found to be similar Thus, it justifies that the chopper resistors in the full scale converters are sufficient to handle the low voltage fault ride through (LVRT) conditions

A wind turbine rotor, a wind turbine and use thereof

Abstract: The invention relates a wind turbine rotor. The rotor comprises at least one wind turbine blade, at least one image capturing device, and one or more markers arranged on the blade so that the at least one image capturing device may detect the position of the markers. The invention further relates to a wind turbine and use thereof.

Wind turbine, a method for controlling the temperature of fluid flowing in a first temperature control system of a wind turbine and use thereof

Abstract: A wind turbine includes a first temperature control system including fluid transporting heat to or from one or more components of the wind turbine. The wind turbine further includes a mechanism for exchanging heat between the first temperature control system and at least one further temperature control system of the wind turbine, wherein a temperature controlled mechanism enables the heat exchange between the first temperature control system and the at least one further temperature control system. A method for controlling or regulating the temperature of fluid flowing in a first temperature control system of a wind turbine and a use hereof is also contemplated.

Assembly and method of preparing an assembly

Abstract: The invention relates to a method of preparing an assembly, comprising providing a first structure; providing a second structure; providing at least one flexible adhesive limiting member extending between said structures; and providing an adhesive between said structures to bind said structures to each other; wherein the adhesive is limited by the flexible adhesive limiting member such that a concave front line surface of the adhesive is defined. The invention also relates to such an assembly as well as to a wind turbine rotor blade, and to a wind turbine, comprising such an assembly.

Wind Energy Converter With Dehumidifier

Abstract: A wind energy converter includes a wind turbine and a climate control mechanism operable as a dehumidifying mechanism for separating and removing humidity from air within one or more areas of the wind turbine. The climate control mechanism includes at least one cooling device for condensing humidity as well as at least one drain device for draining condensed water from the one or more areas being dehumidified. The wind energy converter includes a cooling flow mechanism for providing a flow of a cooling liquid to the at least one cooling device, thereby providing a heat sink for the cooling device.

Model predictive current control for high-power grid-connected converters with output LCL filter

Abstract: A model predictive control strategy for a highpower, grid connected 3-level neutral clamped point converter is presented. Power losses constraints set a limit on commutation losses so reduced switching frequency is required, thus producing low frequency current harmonics. To reduce these harmonics an LCL filter is used. The proposed control strategy allows control of the active and reactive power fed into the grid, reduce the switching frequency within acceptable operational margins and keep balance of the DC-link capacitor voltages while avoiding excitation of the filter resonance frequencies.

Medium voltage three-level converters for the grid connection of a multi-MW wind turbine

Abstract: Three-level (3L) neutral point clamped (NPC), flying capacitor (FC), and H-bridge (HB) voltage source converters (VSCs) as a grid-side full-scale medium voltage (MV) converter are modeled, controlled, and simulated for the grid connection of a hypothetical 6MW wind turbine. Via the converter topological features and the simulation results demonstrating the converter performance, these three 3L-VSCs are discussed and compared in terms of power density and reliability, which can be considered as two of the most important criteria for the converters placed in wind turbine nacelles. Given the grid connection circuit (without capacitive switching ripple filters), the 3L-HB-VSC is expected to be superior with respect to power density and reliability over the 3L-NPC- and -FC-VSCs.

Power curtailment of wind turbines

Abstract: The present invention relates to a method for curtailing electrical power supplied from a wind turbine or a group of wind turbines to an associated power supply grid, the method comprising the steps of determining an available electrical power level from the wind turbine facility and setting a wind speed independent curtailment level. The curtailment level may be a percentage of an actual available electrical power level or a fixed power level. The method further comprises the step of operating the wind turbine facility in such a way that the generated electrical power supplied from the wind turbine facility equals the difference between an actual available electrical power level and the curtailment level. The present invention further relates to a wind turbine facility and a curtailing controller for carrying out the invention.

The Bolund experiment: Overview and background

Abstract: max. 2000 char.): The Bolund experiment is a measuring campaign performed in 2007 and 2008. The aim of the experiment is to measure the flow field around the Bolund hill in order to provide a dataset for validating numerical flow models. The present report gives an overview of the whole experiment including a description of the orography, the instrumentation used and of the data processing. The Actual measurements are available from a database also described. ISSN 0106-2840 ISBN 978-87-550-3703-8 Contract no.: ENS-33033-0062 Group's own reg. no.: 1110058-01 Sponsorship: Energistyrelsen, Danish Energy Agency, Vestas Technology R&D Cover : Picture of the Bolund hill Pages: 51 Tables: 20 References: 13 Information Service Department Risø National Laboratory for Sustainable Energy Technical University of Denmark P.O.Box 49 DK-4000 Roskilde Denmark Telephone +45 46774005 bibl@risoe.dtu.dk Fax +45 46774013 www.risoe.dtu.dk

Foundation for enabling anchoring of a wind turbine tower thereto by means of replaceable through-bolts

Abstract: A foundation for enabling anchoring of a wind turbine tower thereto by means of replaceable through-bolts includes a foundation sole with a set of through-holes for accommodating the through-bolts, wherein the through-holes extend from an upper surface to a lower surface of the foundation sole; a workspace arranged beneath the foundation sole for enabling access to lower ends the through-bolts when arranged in the through-holes; and a passage allowing access to the workspace from a location outside an area of the foundation sole to be covered by the tower. A method for providing such a foundation is also disclosed.

Control of rotor during a stop process of a wind turbine

Abstract: A method for controlling a wind turbine rotor during a stop process by pitching the rotor blades fast, e.g. with an angular rate of 10-15°/s to a no-thrust position, after which the rotor blades are pitched to maintain the no-thrust or a thrust against the direction of the pendulum movement of the tower for a while to prevent the aerodynamic thrust from aggravating the pendulum movement of the tower. With this control strategy, the bending moments of the tower root are minimized, leading to avoidance of wind turbine tower failure, to prolongation of the life time for a wind turbine tower and the possibility of erecting wind turbine towers of less reinforcement at the tower root.

Control of wind park noise emission

Abstract: According to the present invention is provided a method of control of noise emission from a wind park in operation, the wind park comprising a plurality of wind turbines. The method comprises the steps of • providing measurements of at least one wind speed and of at least one wind direction to a park noise emission emulation module including for each of two or more of the plurality of wind turbines a wind turbine noise emission model being suitable for producing a prediction of noise emission from the wind turbine as a function of at least one operational characteristic, the geographical position of each of the plurality of wind turbines, and the geographical position of at least one noise immission point, • emulating the noise level at the at least one noise immission point as a result of noise emitted by the plurality of wind turbines, and • controlling the operation of the wind park from the result of the emulation so as to prevent the noise level at the at least one noise immission point from exceeding a predetermined threshold level. Furthermore, the invention relates to a wind park.

A sectional blade

Abstract: The invention provides a sectional blade for a wind turbine. The blade comprises at least a first blade portion and a second blade portion extending in opposite directions from a joint. Further each blade portion comprises a spar section forming a structural member of the blade and running lengthways. The first blade portion and the second blade portion are structurally connected by at least one spar bridge extending into both blade portions to facilitate joining of said blade portions and the spar bridge joins the spar sections.

Direct power and stator flux vector control of a generator for wind energy conversion system

Abstract: A method for controlling a variable speed wind turbine generator is disclosed. The generator is connected to a power converter comprising switches. The generator comprises a stator and a set of terminals connected to the stator and to the switches of the power converter. The method comprises: determining a stator flux reference value corresponding to a generator power of a desired magnitude, determining an estimated stator flux value corresponding to an actual generator power, determining a difference between the determined stator flux reference value and the estimated stator flux value, and operating said switches in correspondence to the determined stator flux reference value and the estimated stator flux value to adapt at least one stator electrical quantity to obtain said desired generator power magnitude.

Method for damping oscillations in a wind turbine

Abstract: The present invention relates to a method for damping oscillations in a wind turbine comprising a wind turbine tower, a nacelle arranged on top of said wind turbine tower, and a number of rotor blades rotatably connected to the nacelle. The oscillations to be damped originate from forces induced on the nacelle and the wind turbine tower by the rotating rotor blades. The method comprises the steps of providing an internally suspended pendulum mass structure being operationally connected to an upper tower section, providing a platform being fixedly attached to the upper tower section, and providingdamping means comprising one or more friction members being displaceably arranged relative to the platform, the one or more friction members being adapted to be displaced relative to the platform in response to relative movements between the suspended pendulum mass structure and the platform in order to dissipate energy from the suspended pendulum mass structure by friction.

Wind Turbine Blade Position Determination System

Abstract: A system for determining the position of at least a part of a wind turbine blade by wireless transmission of a signal includes a transmitter arrangement attached to a wind turbine blade, a receiving arrangement, and at least one position calculation computer, wherein the signal is wirelessly transmitted from the at least one transmitter arrangement to the receiving arrangement, and wherein the position calculation computer calculates position indicative data on the basis of the signal received by the receiving arrangement and wherein the position indicative data indicates a position of at least a part of the wind turbine blade.

A General Solution for Theoretical Harmonic Components of Carrier Based PWM Schemes

Abstract: In this paper, a general solution for the theoretical PWM harmonic components is presented. Analytical solutions of harmonic components for all PWM schemes can be easily achieved by using it. The method is applicable irrespective of the pulse ratio between the carrier and the fundamental, and the computational requirements are essentially constant irrespective of the absolute value of the carrier frequency. Moreover, it is especially suitable for software calculation of theoretical harmonic components due to the ease of implementation. Compared with numerical integration method and conventional FFT scheme, the computation time of the proposed solution is much less. Simulation results of 5 popular PWM schemes are presented to verify the general solutions.

A lubrication system for a gear system for a wind turbine

Abstract: A lubrication system (1) for a gear system (2) of a wind turbine is disclosed. The lubrication system (1) comprises a first reservoir (3) and a second reservoir (4) adapted to contain lubricant. It further comprises pump means (5, 15, 18) arranged to supply lubricant from the first reservoir (3) to the second reservoir (4) during normal operation, and a distribution system (8) fluidly connected between the first reservoir (3) and the gear system (2) in such a manner that lubricant can be supplied to the gear system (2) from the first reservoir (3) via the distribution system (8) during normal operation. The lubrication system (1) further comprises valve means (10, 12, 23) being shiftable between a first position and a second position. In the first position a flow of lubricant from the second reservoir (4) towards the gear system (2) or the first reservoir (3) is prevented, and in the second position it is allowed. The valve means (10, 12, 23) operates in response to pressure changes in the lubrication system (1) in such a manner that a predetermined pressure change automatically and directly causes the valve means (10, 12, 23) to shift from the first position to the second position. Thereby it is ensured that the lubrication system (1) is automatically, reliably and fast switched to an emergency state in the case that a situation occurs which changes the pressure in the lubrication system (1) in a predetermined manner. It is not necessary to rely on separate measurements of various parameters by independent probes or the like.

Tower, a wind turbine and a method for arranging a platform inside a tower

Abstract: This invention relates to a tower for a wind turbine, comprising one or more tubular tower sections, having an outer jacket wall and an inward directed flange in its lower and upper ends, and at least one platform arranged inside the tower for facilitating access for maintenance and repairs to the inner of the tower and to the nacelle. The tower also comprises a support structure including at least three elongated tensile load carrying members, which each is attached in its upper end to the upper flange of the tower section and in its lower end to the lower flange of the tower section and which supports one or more platforms that are suspended by the tensile load carrying members while at least one ladder is attached to the platforms. The at least one ladder is stabilized in the horizontal direction by transversal tensile load carrying members extending from the ladder to the tensile load carrying members that are vertically arranged between the upper and lower flanges. The invention also relates to a method for arranging a platform inside a tower.

Method and system of performing a functional test of at least one embedded sub-element of a wind turbine

Abstract: A method of performing a functional test of at least one embedded sub-element of a wind turbine, the wind turbine being controlled by a control algorithm of a wind turbine controller, includes the steps of: executing a predefined event pattern activating at least one sub-element of the wind turbine, obtaining measure data on the basis of measurements of at least one sub-element according to the predefined event pattern, and relating the measure data to predefined reference data and establishing a test result indicating the condition of the embedded sub-element on the basis thereof. The predefined event pattern is executed by a test algorithm overriding the control algorithm of the wind turbine controller at least partly. It is a very advantageous feature according to the present invention that the sub-elements may be tested while being embedded in the wind turbine.

Method for sensing strain in a component in a wind turbine, optical strain sensing system and uses thereof

Abstract: The invention relates to a method for sensing strain in a component in a wind turbine comprising an optical sensor system. The method comprises the step of inputting a optical signal into at least one optical fibre of said sensor system comprising one or more fibre Bragg grating sensors. Further, the method comprises the step of measuring the transmitted optical signals of said one or more sensors with at least one light detector connected to the other end of said at least one optical fibre, and processing the measured signals in a control unit in order to establish a value of the strain for the component. The invention also relates to an optical strain sensing system for a component in a wind turbine and uses hereof.

Apparatus and method for assembling wind turbines

Abstract: An apparatus for assembling a wind turbine includes a crane boom having a main bearing cable coupled to a component for lifting the component during assembly of the wind turbine, and a control mechanism coupled to the crane boom for controlling the orientation of the wind turbine component during the lift. The control mechanism includes a guide member coupled to the crane boom, a movable member coupled to the guide member and configured to be movable relative to the crane boom, a coupling member configured to couple the movable member to the wind turbine component being lifted by the crane boom, and a drive mechanism configured to actively move the movable member relative to the crane boom independent of the movement of the main bearing cable. A method for assembling a wind turbine includes using the coupling member to change the orientation of the component.

Method and a controlling arrangement for controlling an AC generator

Abstract: The present disclosure related to a method and a controller for controlling an AC generator which is used in connection with a wind turbine having a variable speed. The multi-phase generator is connected to a controllable converter and is controlled to provide a desired power or a desired torque. An AC reference signal is generated, which would provide the desired power or torque. A P+Resonant converter may be used to control an electrical characteristic of the generator in view of the reference, by applying control signals to the controllable converter. Thereby, the need to transform the electrical characteristic into a rotating frame may be eliminated which provides for a less complex controller.

Method and System for Operating a Wind Power Plant Comprising a Number of Wind Turbine Generators

Abstract: This invention relates to a method and a system for operating a wind power plant (1 ) connected to a power grid (2), the wind power plant comprising a number of wind turbine generators. The method comprises the steps of: setting up (101 ) a number of different models, each model emulating an electrical behaviour of an electrical system, such as a load or a power generating unit, connected to the power grid; detecting (102) value(s) of a number of power grid parameters; selecting (103) one of the number of models, based on a number of values out of a set comprising the detected power grid parameter value(s) and ambient parameter value(s), or based on an external command signal; in the selected model, calculating (104) electrical output values of the model, based on the detected grid parameter values; calculating (105) electrical reference values for the wind power plant, based on the calculated electrical output values of the model; and calculating (106) electrical reference values for each wind turbine generator based on the calculated electrical reference values for the wind power plant. The method may further comprise controlling (107) the wind turbine generators according to the calculated electrical reference values for each wind turbine generator.

Method and system for controlling a wind power plant comprising a number of wind turbine generators

Abstract: This invention relates to a method and a system (10) for controlling a wind power plant (20) comprising at least one wind turbine generator (21 a-n), the wind power plant being connected to a power network (30) for delivering power to the power network. The method comprises: detecting (201 ) a frequency of the power network; calculating (202) a variation rate in the detected frequency of the power network; calculating (203) a requested variation of delivered power for the wind power plant based on a value of the inertia of the wind power plant and the calculated frequency variation rate; calculating (204) a requested variation of delivered power for each wind turbine generator of the wind power plant based on the calculated requested variation of delivered power for the wind power plant and a current power level of each wind turbine generator. The resulting calculated requested power variation is then used for controlling (205) each wind turbine generator to deliver power to the network.

Wind turbine blade load sensor

Abstract: A wind turbine rotor blade root load sensor is provided. The sensor is configured to be internally mounted within an insert of a root portion of a wind turbine rotor blade. The sensor comprises a carrier member which is configured to be fixedly connected to the insert so that loads can be transmitted therebetween and the sensor further comprises a sensing element, supported by the carrier member.