Showing papers by "Vestas published in 2012"

Power Capability Investigation Based on Electrothermal Models of Press-Pack IGBT Three-Level NPC and ANPC VSCs for Multimegawatt Wind Turbines

Abstract: Wind turbine power capability is an essential set of data for both wind turbine manufacturers/operators and transmission system operators since the power capability determines whether a wind turbine is able to fulfill transmission system reactive power requirements and how much it is able to provide reactive power support as an ancillary service. For multimegawatt full-scale wind turbines, power capability depends on converter topology and semiconductor switch technology. As power capability limiting factors, switch current, semiconductor junction temperature, and converter output voltage are addressed in this study for the three-level neutral-point-clamped voltage source converter (3L-NPC-VSC) and 3L Active NPC VSC (3L-ANPC-VSC) with press-pack insulated gate bipolar transistors employed as a grid-side converter. In order to investigate these VSCs' power capabilities under various operating conditions with respect to these limiting factors, a power capability generation algorithm based on the converter electrothermal model is developed. Built considering the VSCs' operation principles and physical structure, the model is validated by a 2 MV·A single-phase 3L-ANPC-VSC test setup. The power capability investigations regarding a sample grid code's reactive power requirement show that 3L-ANPC-VSC results in 32% better power capability than 3L-NPC-VSC at the switching frequency of 1050 Hz. Furthermore, 3L-ANPC-VSC with 57% higher switching frequency (1650 Hz) and 33% smaller switching ripple filter can yield close power capability compared to 3L-NPC-VSC with 1050 Hz.

Negative Sequence Current Control in Wind Power Plants With VSC-HVDC Connection

Abstract: Large offshore wind power plants may have multi-MW wind turbine generators (WTG) equipped with full-scale converters (FSC) and voltage source converter (VSC) based high voltage direct-current (HVDC) transmission for grid connection. The power electronic converters in the WTG-FSC and the VSC-HVDC allow fast current control in the offshore grid. This paper presents a method of controlling the negative sequence current injection into the offshore grid from the VSC-HVDC as well as WTG-FSCs. This would minimize the power oscillations and hence reduce the dc voltage overshoots in the VSC-HVDC system as well as in the WTG-FSCs; especially when the offshore grid is unbalanced due to asymmetric faults. The formulation for negative sequence current injection is mathematically derived and then implemented in electromagnetic transients (EMT) simulation model. The simulated results show that the negative sequence current control mitigates the power oscillations and therefore limits the dc voltage excursions in the VSC-HVDC system during the asymmetric faults.

Wind turbine blades

Abstract: A reinforcing structure 9 for a wind turbine blade is in the form of an elongate stack 27 of layers 31 of pultruded fibrous composite strips supported within a U-shaped channel 28. The length of each layer 31 is slightly different to create a taper at the ends of the stack; the centre of the stack 27 has five layers 31, and each end has a single layer 31. The ends of each layer 31 are chamfered, and the stack is coated with a thin flexible pultruded fibrous composite strip 33 extending the full length of the stack 27. The reinforcing structure 9 extends along a curved path within the outer shell of the blade. During configuration of the blade components within a mould 37, the reinforcing structure 9 is introduced into the mould 37 by sliding the channel 28 along the surface of an elongate wedge 29 within the mould 37 along the curved path. The wedge 29 is oriented along its length at an angle depending on the curvature of the path at that position so as to guide the reinforcing structure 9 into the desired position. The regions of the outer shell of the blade on either side of the reinforcing structure 9 are filled with structural foam 17, and the reinforcing structure 9 and the foam 17 are both sandwiched between an inner skin 18 and an outer skin 19.

Design and Analysis of a Slope Voltage Control for a DFIG Wind Power Plant

Abstract: This paper addresses a detailed design of a wind power plant and turbine slope voltage control in the presence of communication delays for a wide short-circuit ratio range operation. The implemented voltage control scheme is based upon the secondary voltage control concept, which offers fast response to grid disturbances, despite the communication delays, i.e., this concept is based on a primary voltage control, located in the wind turbine, which follows an external voltage reference sent by a central controller, called secondary voltage control, which is controlling the voltage at the point of connection with the grid. The performance has been tested using PSCAD/EMTDC program. The plant layout used in the simulations is based on an installed wind power plant, composed of 23 doubly fed generator wind turbines. The resulting performance is evaluated using a compilation of grid code voltage control requirements. The results show that fast response to grid disturbances can be achieved using the secondary voltage control scheme, and the fulfillment of the design requirements can be extended for a wide range of short-circuit ratios.

Light Rotor: The 10-MW reference wind turbine

Abstract: This paper describes the design of a rotor and a wind turbine for an artificial 10-MW wind turbine carried out in the Light Rotor project. The turbine called the Light Rotor 10-MW Reference Wind Turbine (LR10MW RWT), is designed with existing methods and techniques and serves as a reference to future advanced rotor designs in the project. The results shown in this paper are not for the final design, but for Iteration #2 in the design process. Several issues in the design process were highlighted. Before carrying out the design many decisions have to be made and this paper elaborate on issues like the determination of the specific power and upscaling of the turbine. The design of Iteration #2 of the LR10-MW RWT is carried out in a sequence between aerodynamic rotor design, structural design and aero-servo-elastic design. Each of these topics is described. The results from the Iteration #2 design show a rather well performing wind turbine both in terms of power and loads, but in the further work towards the final design the challenges in the control needs to be solved and the balance between power performance and loads and between structural performance and mass will be investigated further resulting in changes in the present design.

Control of wind turbines

Abstract: A wind turbine power plant comprises a plurality of wind turbines, each having a rated output and under the control of a power plant controller. The power plant also has a rated output which may be over-rated in response to one or more of electricity pricing data, power plant age and operator demand. The power plant controller can send over-rating demand signals to individual turbines. The controllers at the turbines include a fatigue life usage estimator which estimates a measure of the fatigue life consumed by key components of the turbine. If this measure exceeds a target value for any component, over-rating is prevented at that turbine.

Heat sink for cooling of power semiconductor modules

Abstract: A heat sink for cooling at least one power semiconductor module, and that includes a basin for containing a cooling liquid. The basin has a contact rim for receiving the base plate and that includes a surface that is sloped inwards to the basin.

Wind turbine integrated structural and LPV control design for improved closed-loop performance

Abstract: An iterative redesign algorithm is proposed to integrate the design of the structural parameters and a linear parameter-varying (LPV) controller for a three-bladed horizontal-axis wind turbine. The LPV controller is designed for an eighth-order lumped model of the wind turbine consisting of blades, drive-train and the tower. The lumped model response is matched with detailed open-loop numerical simulations using the Fatigue, Aerodynamics, Structures and Turbulence (FAST) code. The controller is scheduled in real-time based on the mean wind speed to account for the varying system dynamics. The objective is to track the operating trajectory meanwhile minimise the H ∞ performance index from the wind turbulence to the controlled output vector consisting of pitch angle, blade tip deflection, and the generator speed and torque. Sensitivity analysis of the closed-loop performance index with respect to the structural parameters of the system is examined. The integrated design problem is formulated as an iterative...

Selective droop response control for a wind turbine power plant

Abstract: A power plant controller (36) is described. The power plant controller (36) controls a power generation system (10) having one or more power generators (12) and an energy storage system (22), and provides a utility grid or transmission system operator with the capability to select the droop response provided by the power generation system. Accordingly, an operator can request a specific generator droop response in order to provide appropriate frequency and grid control services. The power plant controller (36) operates in real time determining one or more power characteristics of the power generation system (10). Based on these characteristics and an indication of a future predicted power output for the power generation system, the power plant controller can take the necessary steps to ensure that the power generation system is capable of responding with the selected droop response, or can advise the operator that a different droop is preferred.

A shutdown controller for a wind turbine and a method of shutting down a wind turbine

Abstract: The invention provides a shutdown controller for a wind turbine. To improve the estimation of a state of the wind turbine,the controller comprises at least two sensors being adapted to provide sensor data significant for different mechanical states in the wind turbine. The controller can provide an estimated state of the wind turbine based on the sensor data from the at least two sensors and compare the state of the wind turbine with a predefined detection limit to provide a shutdown signal if the estimated state is outside the detection limit.

Connection system for power generation system with dc output

Abstract: The present invention relates to a connection system for connecting a power generator to a DC electrical power system, with a controllable voltage source unit functionally connected in series with the power generator to receive AC electrical power from the power generator, and to generate an AC electrical power output accordingly, and a rectifier arranged to receive AC electrical power output from said voltage source unit and to rectify the AC electrical power output to a DC electrical power to be provided to the DC electrical power system. The invention also relates to method for connecting a power generator to a DC electrical power system.

Method and apparatus for protecting wind turbines from extreme events

Abstract: A wind turbine has a scanning Lidar arranged on the nacelle. The Lidar has a single scanning beam which scans about a substantially vertical axis to sense wind related data in a measurement volume a predetermined distance from the Lidar. Fast Fourier transforms of data from a plurality of points in the measurement volume are analysed to derive a peak velocity and a measure of variance. A controller receives the peak velocity and measure of variance as inputs and generates an output if the controller determines that the input data shows that the wind conditions are such that damage to the wind turbine is likely.

Partial-load de-rating for wind turbine control

Abstract: Methods,controllers and computer program products for controlling a wind turbine. Under de-rated operating conditions in which the power requested from a wind turbine is less than the available power, a controller adjusts blade pitch of the wind turbine to reduce the rotor power coefficient. The captured wind power is thereby reduced to be approximately equal to the requested electrical power, which is less than either the available power or the rated power of the wind turbine generator. This reduction in captured power provides the controller with an additional degree of freedom that allows the controller to increase the electrical power output of the wind turbine in response to wind fluctuations without damaging the wind turbine. By allowing increases in power under de-rated conditions, the controller may reduce the amount of pitching necessary to prevent the turbine from exceeding its rated power output level.

Implementation of a Mixing Length Turbulence Formulation Into the Dynamic Wake Meandering Model

Abstract: The work presented in this paper focuses on improving the description of wake evolution due to turbulent mixing in the dynamic wake meandering (DWM) model From wake investigations performed with high-fidelity actuator line simulations carried out in ELLIPSYS3D , it is seen that the current DWM description, where the eddy viscosity is assumed to be constant in each cross-section of the wake, is insufficient Instead, a two-dimensional eddy viscosity formulation is proposed to model the shear layer generated turbulence in the wake, based on the classical mixing length model The performance of the modified DWM model is verified by comparing the mean wake velocity distribution with a set of ELLIPSYS3D actuator line calculations The standard error (defined as the standard deviation of the difference between the mean velocity field of the DWM and the actuator line model), in the wake region extending from 3 to 12 diameters behind the rotor, is reduced by 27% by using the new eddy viscosity formulation

Methodology for assessment of inertial response from wind power plants

Abstract: High wind power penetration levels result in additional requirements from wind power in order to improve frequency stability. Replacement of conventional power plants with wind power plants reduces the power system inertia due to the wind turbine technology. Consequently, the rate of change of frequency and the maximum frequency deviation increase after a disturbance such as generation loss, load increase, etc. Having no inherent inertial response, wind power plants need additional control concepts in order to provide an additional active power following a disturbance. Several control concepts have been implemented in the literature, but the assessment of these control concepts with respect to power system requirements has not been specified. In this paper, a methodology to assess the inertial response from wind power plants is proposed. Accordingly, the proposed methodology is applied to one of the inertial response control concepts from the literature.

Renewable energy configurator

Abstract: Embodiments for determining an optimal configuration for a renewable energy power plant are provided. The power plant, which may be a virtual power plant, includes one or more generator devices and one or more energy storage devices that may be operated to undertake one or more operating applications. Data indicative of the power output of the power plant and the voltage level at the energy storage system connection point is received as an input. Using this data, combinations of energy storage devices and operating applications stored on a database are processed and, for each energy storage and operating application pair, a value indicative of the profitability of undertaking the operating application is determined. These values are used to rank the combinations of energy storage devices and operating applications according to their profitability, which in turn is used to select the most efficient or profitable application/energy storage pair.

A method for improving large array wind park power performance through active wake manipulation reducing shadow effects

Abstract: Embodiments of the present invention provide methods and apparatus for increasing turbulent mixing in the wake of at least one wind turbine. Doing so, increases efficiency of a wind turbine located in the wake by transferring energy to the wake that was lost when the wind passed through the upwind turbine. Turbulent mixing may be increased by changing the induction factor for a rotor by, for example, altering the pitch of the blades, the RPMs of the rotor, or the yaw of the nacelle. These techniques may be static or dynamically changing. Further, the different induction factors for a plurality of wind turbines may be synchronized according to a predetermined pattern to further increase turbulent mixing.

Operating wind turbines under converter faults

Abstract: A wind turbine is arranged to operate in a fully-functional converter mode and a faulty-converter mode. A plurality of converters are arranged to share electric current in the fully-functional converter mode. The converters are dimensioned not only to operate at nominal active current but to provide an over-current margin to enable reactive current to be produced on top of the nominal active current in the fully-functional converter mode. In the fully-functional converter mode the converters are caused to produce reactive current on top of the nominal active current. In response to a fault of one or more of the converters, operation is changed from the fully-functional converter mode to the faulty-converter mode. In the faulty-converter mode, one or more other converters of the converter system are caused to produce additional active current by using their over-current margin to compensate at least partly for a reduction of active-current production due to the fault of one of the converters, and to reduce the reactive-current production by the other converter correspondingly.

System and method for controlling power output from a wind turbine or wind power plant

Abstract: A LIDAR or other remote sensing apparatus is mounted on a wind turbine to sense one or more wind parameters. An extreme event detector processing signals from the LIDAR to determine whether a given sensed parameter will, when it arrives at the turbine, exceed a predetermined value and represent an extreme event. On detection of an extreme event, the detector outputs an extreme event signal to a controller. The controller controls overrating of the turbine in response to a variety of sensed parameters and selectively operates the turbine at above rated wind speed. On receipt of the extreme event signal the overrating is overridden to prevent damage to turbine components. The controller may be a power plant controller and the override signal may override only overrating at the turbine which has detected the extreme event, or a plurality of turbines.

Acoustic noise monitoring system for a wind turbine

Abstract: The present invention relates to an acoustic noise monitoring system for a wind turbine, comprising: a microphone for monitoring acoustic noise, the microphone adapted to be mounted to the exterior of a wind turbine nacelle; an input, the input adapted to receive operating conditions data from a wind turbine; a processor, the processor adapted to receive data from the microphone and the input; and storage memory, adapted to store the acoustic noise data and the operating conditions data. The processor is adapted to apply a transfer function to said acoustic noise data to correlate said data with a set of acoustic noise data measured at a remote location from the wind turbine. The system may comprise a controller adapted to generate a control signal, for outputting to a wind turbine controller, for adjusting the operating parameters of the wind turbine in dependence on said correlated data.

Wind turbine having heliplatform arrangement and method of using same

Abstract: A wind turbine for generating electrical energy may include a tower, a nacelle at the top of the tower, and a rotor coupled to a generator within the nacelle. The wind turbine further includes a cooler including a spoiler and at least one cooler panel projecting above a roof of the nacelle. A heliplatform includes a support structure extending from the nacelle and at least partially integrated with the cooler. The wind turbine may also include a crane coupled to the nacelle and configured to move between a first stowed position underneath the nacelle roof and a second operational position. In the operational position, the crane is selectively positionable over the heliplatform. A method of using the wind turbine and crane is also disclosed.

Active power control with undead-band voltage &p frequency droop applied to a meshed DC grid test system

Abstract: A new method for controlling active power in HVDC grids has been tested on the meshed CIGRE B4 DC grid test system. The control strategy is based on the recently proposed undead-band droop control, which combines DC voltage and AC frequency droop. It provides sufficient room for optimisation for both normal and disturbed operation. Its main features are flexibility, reliability due to distributed control, easy expandability of the system and minimisation of communication needs. The control technique has been tested and its effectiveness has been verified to demonstrate its suitability for application in future meshed HVDC grids.

Wind power plant control system, wind power plant including wind power plant control system and method of controlling wind power plant

Abstract: The invention relates to a wind power plant control system arranged for controlling one or more wind turbine generators in a wind power plant, wherein the wind power plant control system comprises a power plant controller and a modeling unit, the modeling unit being operatively coupled to the power plant controller. The modeling unit is arranged to calculate estimated values of electrical output parameters from the one or more wind turbine generators, and to output said estimated values to the power plant controller. The power plant controller is arranged for determining reference signals for dispatching to the one or more wind turbine generators, wherein the estimated values of said electrical output parameters are used by the power plant controller in the determination of said reference signals. The invention also relates to a corresponding method of controlling a wind power plant.

A wind turbine blade ice accretion detector

Abstract: A wind turbine blade ice accretion detector 65 is configured to receive an indication of power generated by a wind turbine 67 and an indication of a plurality of environmental conditions of the wind turbine 69. It is also configured to receive an indication of an error relating to the operation of the wind turbine71. These indications are processed by the detector 65 to provide an indication of ice accretion of a wind turbine blade. In addition to or as an alternative, the wind turbine blade ice accretion detector 65 is configured to receive an indication of power generated by a wind turbine 67 in a plurality of different time periods and an indication of a plurality of environmental conditions of the wind turbine 69 in the plurality of different time periods; and to process these to provide an indication of ice accretion of a wind turbine blade.

Wind turbine generator with localized air gap control and a wind turbine having such a generator

Abstract: A wind turbine component ( 18 ) includes an inner member ( 32 ) and an outer member ( 34 ) disposed relative to the inner member ( 32 ), wherein the inner and outer members ( 32, 34 ) move relative to each other A plain bearing ( 200 ) is coupled to one of the inner or outer member ( 32, 34 ) and configured to provide a fluid film ( 202 ) for maintaining separation of and facilitating relative movement between the inner and outer members ( 32, 34 ) A position adjustment mechanism ( 78 ) is coupled to the one of the inner or outer member ( 32, 34 ) for selectively moving the plain bearing ( 200 ) A position controller ( 176 ) may be operatively coupled to the position adjustment mechanism ( 78 ) for controlling the position of the plain bearing ( 200 ) The wind turbine component may be a wind turbine generator ( 18 ) with the inner member and outer member corresponding to one of the stator and rotor assemblies ( 32, 34 ) Methods for controlling the generator are also disclosed

A method of yawing a rotor of a wind turbine

Abstract: A wind turbine (1) in which the yaw speed of a rotor (4) of the wind turbine (1) is increased, in a direction to reduce yaw error, from a first speed to a faster second speed when at least one of a yaw error threshold and a rate of change in yaw error threshold is exceeded. Yaw error is an amount an axis about which the rotor (4) is rotatable is offset from the wind direction to which the rotor (4) is exposed. As a result, the maximum loads that a wind turbine 1 should withstand may be reduced and lighter wind turbine components result.

An iterative approach for symmetrical and asymmetrical Short-circuit calculations with converter-based connected renewable energy sources. Application to wind power

Abstract: As more renewable energy sources, especially more wind turbines are installed in the power system, analysis of the power system with the renewable energy sources becomes more important. Short-circuit calculation is a well known fault analysis method which is widely used for early stage analysis and design purposes and tuning of the network protection equipments. However, due to current controlled power converter-based grid connection of the wind turbines, short-circuit calculation cannot be performed with its current form for networks with power converter-based wind turbines. In this paper, an iterative approach for short-circuit calculation of networks with power converter-based wind turbines is developed for both symmetrical and asymmetrical short-circuit grid faults. As a contribution to existing solutions, negative sequence current injection from the wind turbines is also taken into account in calculations in case of asymmetrical faults. The developed iterative short-circuit calculation method is verified with time domain simulations.

Distributed fault-tolerant control and protection system

Abstract: The present invention relates to a distributed fault-tolerant control system for a modularized wind turbine or wind power plant system comprising sub-assemblies, the control system comprising 1) fault-tolerant control means adapted to generate control set-points and/or data values, said fault-tolerant control means being distributed in sub-assemblies in accordance with the modularization of the wind turbine or wind power plant system, and 2) fault-tolerant communication network for transmitting control set-points and/or data values at essentially the same time to a plurality of nodes in the distributed control system, said plurality of distributed nodes being capable of selecting a valid transmission package out of two or more transmission packages provided on the fault-tolerant communication network.

Modular Multilevel Converter Modelling, Control and Analysis under Grid Frequency Deviations

Abstract: A tool for component sizing for MMCs has been developed and tested through simulations in PLECS. The steady-state behaviour under grid frequency deviations - interesting for offshore wind farm connections - has been analysed, providing insights in MMC characteristics and further testing the proposed tool.