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New Advances in Wind Turbine Technology

15th February, 2011

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WinWinD turbines are variable speed, pitch

regulated

The rotor is combined with the integrated power unit

using a robust bearing.

The planetary gear increases the rotating speed modestly

The low speed permanent magnet generator produces

electricity

The frequency converter adapts the electricity to meet

the grid requirements

WinWinD approach

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Rotor bearings and Gearbox

Generator and Converter

Rotor bearings transfer the rotor loads from the hub into the machine housing, skipping the planetary gear and the generator and keeping the drive train free from deformation and loads

The planetary gear increases the rotating speed modestly (noise and highly stressed parts avoided)

The low rotational speed and the small number of rotating parts reduce the risk of damage in the drive train

Low Speed Permanent Magnet Synchronous Generator with high partial power efficiency and less losses

The frequency converter (full conversion) ensures maximum grid compatibility and high power quality (Grid requirements compliance)

Variable speed, pitch regulation

Variable speed, pitch regulated rotor ensures the power control of the turbine and the optimum energy yield over the full range of operational wind speeds

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WinWinD approach WWD brings a proven commercially viable technology evolution from the old standards

Gearbox technology

Generator technology

Load transmission

Frequency converter

Traditional Gear system

Three stage gearbox– High speed shaft with

increased risk of failure and higher mechanical losses.

If an asynchronous generator is used directly on the grid (hard drive train) the load level and the power fluctuations are high, with potential wind turbine stops

The vibration level requires elastic suspension which may induce a risk for the bearing arrangement, with potential risk of failure

Partial scale power conversion in case of doubly-fed generators

FRT not capable for squirrel cage generators

Direct Drive– Low rotation speed; there is no

gear.

Synchronous generator, electrically excited: The excitation losses reduce the efficiency and increase the pole-wheel mass

Direct Drive (Gearless)

The loads may influence the generator air gap and therefore the generator casing needs to be very rigid (weight)

Full scale power conversion

FRT capable

WinWinD Technology

Planetary gear– Low - Medium speed rotation. No helical

stage excludes problems with no load bearing failures in the last stage

– Higher efficiency compared to traditional gear system

Permanent magnet synchronous generator– Increases efficiency up to 5% in low wind

speeds

– High generator efficiency (ca 97%) over a wide speed range

The main bearing is a moment bearing between hub and casing– The influence on gear and generator are

well-known and small and exclude the slow speed shaft dynamics problems

Full scale power conversion

FRT capable

Introduction date 70’s 90’s 2000

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WinWinD approach

WinWinD Technology: advantages

Reliability (More running hours)

The slow speed gearbox reduces the number of bearings inside the gear minimising the probability of failure …– … and it also reduces the mechanical losses caused by the additional gear of traditional gear drive

systems

The compact bearing ensures a well defined flow of forces, low stress and strain, and very small drive train deformations (loads are avoided in the drive train)– The loads from the rotor are transferred to the main casing with its consequent impact on longer

gearbox lifetime when compared with traditional systems

– While industry has faced reliability issues with gearboxes, WinWinD has never had a gearbox broken

The use of a slow speed gearbox means that highly stressed parts are avoided– Components have lower load levels

– Robust slow speed parts

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Efficiency Grid compatibility

Permanent Magnet Synchronous Generator (PMSG) turbine with less components reduces the maintenance needs– They can be brushless

– No slip ring needed

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Advantages

Better availability (less downtime)

Longer life of the turbine

More output

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Permanent Magnet Synchronous Generator (PMSG) contributes to a greater turbine efficiency – At low wind speeds, high partial power efficiency, and consequently a better power curve when

compared to traditional generator systems

– PMSG do not need external excitation

– PMSG generate less losses than other generators in the industry (Squirrel Cage Induction Generators and Double Fed Induction Generators)

WinWinD approach

WinWinD Technology: advantages

Reliability

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Efficiency (More Output) Grid compatibility

PMSG are specially apt for demanding weather conditions, as they produce lower thermal stress on the generator and the bearings

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Aerodynamic blade layout optimised to maximise power output7

Advantages

Higher wind efficiency

More output

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WinWinD approach

WinWinD Technology: advantages

Reliability EfficiencyGrid compatibility (Better

energy)

Full power frequency converters with automatic grid synchronisation ensures maximum grid compatibility and high power quality – Grid friendly turbines

– Low power fluctuations

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Low Voltage Fault Ride Through (LVFRT) Capable, and consequently capable of meeting demanding grid requirements from grid operators

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Advantages

Excellent power quality

Stable output

Grid stabilization during high winds

Low harmonics

Active and reactive power control

LVFRT

Operation in large voltage or frequency fluctuations.

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Load transmission WinWinD’s drive trains are not harmed by the loads coming from the rotor. The small influence is known and considered in the design and calculations

In WinWinD turbines, the loads from the rotor are transferred to the tower through the main bearing, gearbox casing and main frame

In traditional 3-point suspensions the rotor loads react on the gearbox casing and main bearing

– The elastic deformations can lead to unwanted forces on the gearbox. The axial force may cause damage to the double-row spherical ball bearing.

A unique technology

Tower

Mainframe

Gearbox and generator

Rotor

Tower

Rotor

Gearbox

Original concept

WinWinD turbines

Generator

Rotor loads

WinWinD has never had a broken gearbox, as the loads are transmitted directly into the tower

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Planetary GearWinWinD Technology came as the answer to industry’s need for a reliable and effective gear system

Major implications on the choice of gear system

Drive train systems comparison Implications for clients

Size / Weight

Cost

Reliability

Mechanical losses

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- +

- +

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DDG

DDG

G

GDD

H

H

DDH

H

H WinWinD: Simple planetary gear

G Gear (traditional): 3 stage gear

DD Direct Drive: gearless

The low rotational speed of a direct drive shaft demands a larger generator ring (than gear systems), which increases the tower top mass

– Demand stronger towers and foundations

By inserting a simple planetary system, the need for a larger generator ring decreases thus reducing the turbine size and weight

WinWinD technology yields a higher turbine cost as compared to gear concepts but not as expensive as gearless (DD) systems

– The higher turbine cost for a DD systems is a consequence of the higher mass and the extra resulting cost (copper for generators, steel for special towers)

WinWinD’s planetary gear reliability has a solid track record: never has a gear been replaced in WWD turbines

– Less components are needed, thus minimizing the number of potential faulty points

– The helical gears have a smooth and gradual engagement of the teeth thus increasing the lifespan of the components

The additional stages of the traditional gear system mean additional mechanical losses when comparing to WinWinD technology

WWD has an integrated design of the gear with the generator, thus eliminating the main shaft, helical stage(s) and the high speed shaft; making the drive train more efficient by having less rotating components and less vulnerable to excess vibrations which can occur in a bi-axial design having high rotational speed

Broken Gears have been the industry’sheadache for the

past years

The biggest and heaviest

The most expensive

The most reliable

Maximum mechanical losses

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Generator WinWinD uses a permanent magnet synchronous generator which has considerable advantages over other industry standards

Turbine performance comparison depending on different generator types 1

Advantages of using PM synchronous generators over electrically excited machines

High efficiency

High energy yield even in low wind speeds as no excitation power required

Lower thermal stress

Higher reliability without slip rings

Higher power/weight ratio

It is brushless (nearly maintenance free)

PMSG wind turbines with full scale converter can easily comply with FRT than DFIG

A Permanent Magnet synchronous generator is the perfect fit for a variable speed wind turbine with planetary gear configuration

SCIG DFIG EESG PMSG

Efficiency

Reliability

Grid compatibili

ty

High

Low

WWD generatorTime development

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Frequency ConverterFrequency converter ensures full power conversion even at low RPM and ensures full FRT capability

“Grid friendly” turbine

frequency converter

wind turbine control

generator sideconverter

line sideconverter

10 ... 24 kV, f = 50 Hz

line coupling transformer

main circuitbreaker

medium voltageswitchgear

DC

Converter control

The full-power inverter:

– Ensures Full FRT (Fault ride through) capability, and variable reactive current without switching steps

– Q(U) voltage stabilisation function is possible

– Full speed range from starting wind to rated without limitations as with a doubly-fed generator

– Eliminates downtime during voltage dips

– Output stabilization during high wind season

– Can provide reactive power to support voltage levels

WWD turbines are “grid friendly” turbines

There are several issues that wind turbines must address to produce electricity: reactive power, adaptability to grid voltage and frequency changes, reaction to voltage dips, grid adaptation, …

The WinWinD turbine frequency converter is based on IGBTs on generator and grid side, using a switching frequency of 2-3 kHz

– When compared with other configurations, this helps to achieve a minimal grid reaction and high power quality, and fulfill with demanding grid operators rules

– The frequency converter increases the reliability of the grid where the WTG is connected

Advantages of using a frequency converter

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Grid IntegrationWinWind turbines allow full grid integration of produced electricity

Consequently, WinWinD turbines are able to provide:

– Excellent power quality

– Low harmonics

– Low Voltage Fault Ride Through (LVFRT)

–Operation in large voltage or frequency fluctuations

–Active and reactive power management

WWD turbines guarantee a profitable, stable, reliable and high quality supply of electricity

The usage of an IGBT converter ensures compliance with the most demanding grid connection requirements

According to Garrad Hassan (April 2009),the following requirements are now essential for a wind turbine, to

guarantee grid compatibility: (i) good reactive power control; and (ii) reduced

power and voltage fluctuations

WinWinD turbines are...

–… capable of being integrated into existing power systems (different electricity source mixes)

–… prepared to accomplish the restrictions imposed by grid operators, with high level of flexibility and consequently prepared to be easily integrated in any transmission or distribution network

–… prepared to support grid critical situations (short circuits, bottlenecks, …), improving consequently system stability and security of supply

–… ready to control and regulation of power output without power peaks

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Control systemWinWinD control system ensures optimal operation and active security

Measured data is constantly evaluated in order to adapt nacelle yaw control to wind conditions

For all wind speeds, variable speed to achieve maximum wind turbine efficiency

Elimination of undesired output peaks and high operating load

Active pitch control system, with three independently operated pitch mechanisms

Vibrations in tower and generators are monitored

Grid connection monitoring, enabling the turbine to react immediately to changes in voltage or frequency

The control system adjusts the individual system parameters to ensure that WWD turbines achieve maximum output under all weather and wind conditions and work in conformity to the grid

Control System

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Control systemAllows full control and monitoring of WWD turbines performance and operating conditions

Turbine control

Allows optimisation based on the needs of the customer

– Production optimised versus noise optimised power curve

Prepared for small to large wind park configurations

Reporting

Monitoring the functions of the wind turbine

–Weekly, monthly or annual production

–Status of different functions

–Real time grid measurement

Storage of statistics is also available

Remote control

Remote access: WWD turbines can be fully remote controlled

Settings of the main frame can be changed remotely

Alarms

In case of a malfunction the system alarm informs the central control room or any pre-programmed telephone number

Self -diagnosis

The control system continuously protects and controls the turbineand adjusts the turbine settings according to wind and weather conditions

Other options

Transformation of production data information into other information systems (Excel or Access)

Data available on the Internet (username and password protected)

User defined language

User friendly design

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Condition monitoring

The condition monitoring system ensures the mechanical reliability of the turbine.

The system consists of a central unit and vibration sensors, and also receives process signals from the turbine controller.

The data is analysed and a warning is given if the alarm limits are exceeded. In this way a potential problem is known well in advance of it causing the turbine to stop, and the repair can be planned in advance and carried out at the most beneficial time period.

The system also provides trends, frequency spectrums and time domain signals as well as technical details of the wind turbine to enable accurate condition analysis.

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Implementation

Customer

Requirements

System Design

Sub-system Design

Component DesignComponent

Verification

Sub-system

Verification

System Verification

Customer

Satisfaction

Verification

Requirements

Customer Focused Customer

Experience and Feedback

Verification

Requirements

Feasibility

Feedback

Feasibility

Feedback

Integrate Hardware &

Software

Integrate Hardware &

Software

Customer

Requirements

Definition /

Translation

Cascade Requirements and

Architecture Down

Cascade Requirements and

Architecture Down

Product Development Approach

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Test PieceTest Piece

Force Application System

Reaction Load Measurement

Frame and Nacelle Adjustment

Torque Input System

Building and

Foundation

Main Bearing

Control System

Data Acquisition

Test Rig Overview

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Future Turbine Drivetrains

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THANK YOU.