VOLTAGE SAG COMPENSATION FOR PROVIDING WIND

TURBINE LOW VOLTAGE RIDE THROUGH CAPABILITY

Wind to Power System

INDEX

• Organization Chart

• History

• Business Model

• Current Clients

W2PS

• Global Scenario

• Spanish Requiremensts

CompensationSystems • Spanish RequiremenstsSystems

• System Description

• Main Features

• Experimental Results

• Comparison with solutions at substation level

Coverdip

W2PS

• Organization Chart

• History

• Business Model

• Current Clients

W2PS

• Global Scenario

• Spanish Requiremensts

CompensationSystems • Spanish RequiremenstsSystems

• System Description

• Main Features

• Experimental Results

• Comparison with solutions at substation level

Coverdip

W2PS

� WIND TO POWER SYSTEM (W2PS) is a cutting-edge company in the field of renewable energy technology

� W2PS provides innovative power electronics based solutions for the integration of renewable energy in the grid.

� W2PS was created in 2006 as the merging of an university spin-off and Element Power.

University Spin-off

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CURRENT ORGANIZATION CHART

CHIEF EXECUTIVE OFFICERCHIEF EXECUTIVE OFFICERCHIEF EXECUTIVE OFFICERCHIEF EXECUTIVE OFFICERJosé Manuel Corcelles José Manuel Corcelles José Manuel Corcelles José Manuel Corcelles

CHIEF TECHNICAL OFFICERCHIEF TECHNICAL OFFICERCHIEF TECHNICAL OFFICERCHIEF TECHNICAL OFFICERDSMDSMDSMDSM

BUSINESS DEVELOPMENT DIRECTORBUSINESS DEVELOPMENT DIRECTORBUSINESS DEVELOPMENT DIRECTORBUSINESS DEVELOPMENT DIRECTORJLRAJLRAJLRAJLRA

CHIEF SCIENTIFIC OFFICER CHIEF SCIENTIFIC OFFICER CHIEF SCIENTIFIC OFFICER CHIEF SCIENTIFIC OFFICER SAGSAGSAGSAG

STAFFSTAFFSTAFFSTAFF

5

DSMDSMDSMDSM JLRAJLRAJLRAJLRASAGSAGSAGSAG

HISTORY

2006200620062006 W2PS is founded as the merging of an university spin-off and Element Power

2006200620062006

2007200720072007

2007200720072007 RD 661/07 makes P.O. 12.3 requirements mandatory

2007200720072007 W2PS develops COVERDIP (Voltage Dips Compensator)

2007200720072007 W2PS develops STATCOM (Static Synchronous Compensator)

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20082008200820082008200820082008 COVERDIP allows Careón wind farm to obtain P.O.

12.3 response requirements certificate

mandatory

2008200820082008 COVERDIP complyment accredited by the independent testing laboratory LCOE

BUSINESS MODEL

� W2PS provides global solutions to power producers from design to operation and maintenance

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Research & Intellectual

Rights Protection

Product Development

Manufacturing Installation Commissioning O&MStock

� Main Suppliers:

CLIENTS

EUFER: Enel Unión Fenosa Renovables.

RWE: for its spanish subsidary AERSA.

In 2008 W2PS installed more than 250 equipments in different wind farms and more than 650 units have already been signed for

2009.

Main clients:

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ACS/COBRA: for its subsidary EYRA.

EDP Renováveis : for its subsidary NEO Energía.

FALCK RENEWABLES

GRUPO ADELANTA : for its subsidary Montouto 2000.

COMPENSATION SYSTEMS

• Organization Chart

• History

• Business Model

• Current Clients

W2PS

• Global Scenario

• Spanish Requiremensts

CompensationSystems • Spanish RequiremenstsSystems

• System Description

• Main Features

• Experimental Results

• Comparison with solutions at substation level

Coverdip

GLOBAL SCENARIO FOR COMPENSATION SYSTEMS

� Voltage dips (or sags) are abrupt voltage drops from 10% to 99% during 1 ms to 1 minute due to grid faults or large motor starting.

� Voltage dips can provoke the disconnection of wind turbines due to short-circuit currents or to rotor acceleration.

� The lost of a high amount of wind power in an electrical system can seriously affect the stability and security of the electrical system.

� With increasing wind power penetration in power systems, SO´s are demanding new requirements to wind farms.

� From the LVRT capability, the new requirements are extending to voltage and frequency control, inertia emulation, power system stabilization, etc.

AS LONG AS RENEWABLE ENERGY SHARE INCREASES GRID CODES WILL DEMAND SIMILAR

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COMPENSATION SYSTEMS NOT ONLY GARUANTEE GRID STABILITY

BUT ALSO ELIMINATE THE TECHNICAL RESTRICTIONS FOR INSTALLING NEW RENEWABLE ENERGY FACILITIES

AS LONG AS RENEWABLE ENERGY SHARE INCREASES GRID CODES WILL DEMAND SIMILAR

CONTROL ABILITY TO THOSE OF CONVENTIONAL POWER PLANTS FOR GRID OPERATION AND CONTROL

SPANISH LVRT CAPABILITY REQUERIMENTS

� P.O. 12.3 establishes the requirements of the wind turbine response to voltage dips.

� RD 661/2007 makes mandatory the fulfillment of P.O. 12.3 to all wind turbines, new or existing.

� Wind turbine manufacturers are providing solutions for the LVRT capability in new wind turbine, but in

many cases existing wind turbines are not retrofitted by the WT manufacturer.

� W2PS provides a solution for the LVRT capability that is independent of the WT technology and therefore

suitable for any wind turbine model in the market.

P.O. 12.3 Requirements

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COVERDIP

• Organization Chart

• History

• Business Model

• Current Clients

W2PS

• Global Scenario

• Spanish Requiremensts

CompensationSystems • Spanish RequiremenstsSystems

• System Description

• Main Features

• Experimental Results

• Comparison with solutions at substation level

Coverdip

W2PS VOLTAGE SAG COMPENSATOR: COVERDIP

� Wind to Power System (W2PS) has developed an innovativevoltage sag compensation system, named Coverdip, that allowsto inmunize sensible loads to such electric disturbances.

� Beyond the state of the art of Dynamic Voltage Restorers (DVR),Coverdip uses an innovative converter topology that allowsseries connection in the feeder without employing an insertiontransformer.

� The main field of application is to provide wind turbine low� The main field of application is to provide wind turbine lowvoltage ride through capability as specified in the OperationalProcedure 12.3 of the Spanish SO, REE. Althoght, it can be alsoemployed in any other industrial sector.

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MAIN FEATURES (I)

� Series connection without transformer

� Voltage sag compensation at the generator terminals

� Provides wind turbine LVRT capability as required in P.O. 12.3.

� Application to existing wind turbine without LVRT capability.

� Dynamic control of reactive power

� Reactive control during the voltage sag to meet the requirements of P.O. 12.3

Provides the wind turbine with the reactive capacity required to reach maximum � Provides the wind turbine with the reactive capacity required to reach maximum reactive bonus established in the RD 661/2007

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MAIN FEATURES (II)

� Control of the electric generator

� Dynamic control of reactive power and voltage at the generator.

� Soft starting through continuous increasing of voltage at the generator.

� Losses optimization by means of operation at reduced voltage at low load.

� Generator flux damping following an electric disturbance (power andtorque oscillation damping)

TECHNICAL FEATURES

� Rated voltage: 690 V� Rated voltage: 690 V

� Rated power: 600 / 750 / 900 kW

1350 / 1500 / 1650 kW

� Rated current: 500 / 625 / 750 A

1125 / 1250 / 1375 A

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MAIN FEATURES (III): SIZE AND WEIGHT

Filter

ConverterOperationandcontrol

Resistences

Aprox. weight 300 Kg

Rated Power 750 kW

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SYSTEM DESCRIPTION: WIND TURBINE INTEGRATION

GENERADOR TRANSFORMADOR

BT 690 V MT 20 kV o 30 kV

LÍNEA SUBTERRÁNEA INTERIOR DEL

MT 20 kV o 30 kV

BT 690 V

LÍNEA DE EVACUACIÓN DEL PARQUE

AT 66 kV o 132 kV

Coverdip installation inside a wind turbine

COVERDIP

GENERADOR TRANSFORMADORBT/MT INTERIOR DEL

PARQUE EÓLICODEL PARQUE

EÓLICO

AEROGENERADOR

CENTRO DE TRANSFORMACIÓN

DEL PARQUE EÓLICO

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Coverdip is a solution at the wind turbine level

SYSTEM DESCRIPTION

LÍNEA DE EVACUACIÓN DEL PARQUE EÓLICOCOVERDIP

GENERADOR TRANSFORMADORBT/MT

BT 690 V MT 20 kV o 30 kV

LÍNEAS SUBTERRÁNEAS INTERIORES DEL PARQUE EÓLICO

MT 20 kV o 30 kVBT 690 V

AT 66 kV o 132 kV

AEROGENERADOR CENTRO DE TRANSFORMACIÓN DEL

PARQUE EÓLICO

GENERADOR TRANSFORMADOR

BT 690 VBT 690 V

Wind FarmCOVERDIP

GENERADORBT/MT

COVERDIPGENERADOR TRANSFORMADOR

BT/MT

BT 690 VBT 690 V

AEROGENERADOR

AEROGENERADOR

Wind Farm

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EXPERIMENTAL RESULTS I

0 0.5 1 1.5-1000

0

1000

tens

ione

s (V

)

Three phase fault

Voltage at the

Transformer

Terminals

0 0.5 1 1.5

-1000

0

1000

tens

ione

s (V

)

0 0.5 1 1.5

-1000

0

1000

tiempo (s)

corr

ient

es (

A)

Voltage at the

Generator

Terminals

Feeder

Current

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EXPERIMENTAL RESULTS II

Phase to Phase Fault

Voltage at the

Transformer

Terminals

Voltage at the

0 0.5 1 1.5-1000

0

1000

tens

ione

s (V

)

1000

tens

ione

s (V

)

Voltage at the

Generator

Terminals

Feeder current

0 0.5 1 1.5

-1000

0

tens

ione

s (V

)

0 0.5 1 1.5

-1000

0

1000

tiempo (s)

corr

ient

es (

A)

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TECHNICAL COMPARISON OF SOLUTIONS I

Solution Equipment Voltage Sag Reactive LossesDynamic

control

Rated

PowerInstallation

Paralell STATCOM* - + + - + -

Series DVR** + - - - - -

Paralell STATCOM - + - - + +

Series DVR + - - + - +

(*) STATCOM: Static Synchronous Compensator

(**) DVR: Dynamic Voltage Restorer (Standard with insertion transformer)

Wind Farm

Wind Turbine

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� Series solutions are more suitable for voltage sag compensation

� Paralell solutions are more suitable for reactive compensation.

� Solutions at wind farm level:

� Are more difficult to install as they require administrative permit

� Require higher IP from meteorological and environmental fenoma, like rain, dust, etc.

� Solutions at wind turbine level:

� Are easier to install as they are arranged inside the WT tower

� Require lower IP than outdoor arrange

TECHNICAL COMPARISON OF SOLUTIONS II

� COVERDIP is a a series solution for voltage sag compensation at the wind turbine level without

transformer:

� reduced operation losses as it does not use a transformer

� allows the dynamic control of the generator because of its direct connection to generator terminals

� arranged inside the wind turbine tower because it does not use a transformer (less weight and

volume)

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CONCLUSIONS

� COVERDIP allows to meet the LVRT capability requirements established in the P.O. 12.3.

� It has dynamic reactive power capability, so it can also be employed to reach the maximum

reactive bonus established in the R.D. 661/2007.

� Reduce cost per MW compensated.

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