integration of dfig wind generation

8/10/2019 Integration of Dfig Wind Generation

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Presented by,Ashutosh K Kushwaha

Guided By,

Mr. Parag Chourey

Grid Integration of large DFIGBased

Wind Farms Using VSC Transmission


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INDEX

Introduction

Wind turbine generator.

Basic circuit diagram of DFIG based on VSC

transmission . Construction of DFIG

Feature of DFIG

Operation of DFIG

Advantages of DFIG

Feature of VSC based HVDC transmission

system

Benefits of VSC


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INTRODUCTION

We are using voltage source converter(VSC)based- HVDC transmission system technology forconnecting large double fed induction generatorbased wind farms over long distances.

To obtain smooth operation, the wind farm sideVSC is controlled as an infinite voltage sourcethat automatically absorbs power generated bywind farm and maintains a stable local acnetwork.

Fault ride through of the system during grid acfault is achieved by ensuring automatic powerbalancing through frequency modulation usingVSC and frequency control using DFIG.


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Wind Turbine Generator

Squirrel Cage Induction generators driven byfixed speed

Induction Generator with variable external source

rotor resistance driven by variable speed pitch

regulated wind turbine.

Doubly fed induction generator driven by variable

speed, pitch regulated wind turbines

Synchronous or Induction Generators with full

converter interface (back-to-back frequency

converter), driven by variable-speed, pitch regulated

wind turbines


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Basic Circuit Diagram Of DFIG

Based on VSC transmission


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Construction

Turbine

Gearbox.

VSC based on IGBT.

DC link Capacitor. Double Fed Induction Generator.

AC Filter.

Coupling Transformer.


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DFIG Feature

DFIGs have the ability to hold electrical torqueconstant

rapid fluctuations in mechanical power can be

temporarily stored as kinetic energy

Improves power quality.

Performance for large disturbances requires thorough

analysis

May lead to separation of unit.

process may not be readily apparent from simplified

dynamic simulations


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Operation of DFIG Doubly-fed induction generators are commonly used

in wind turbines to generate large amounts ofelectrical power.

mechanical power at the machine shaft is convertedinto electrical power supplied to the ac power network

via both the stator and rotor windings. the machine operates like a synchronous generator

whose synchronous speed can be varied by adjustingthe frequency of the ac currents fed into the rotorwindings.

This DFIG operates like a single fed inductiongenerator only the difference is that for rotor field weare applying AC currents which generated by thewind farm.

The magnetic field created by rotor field is directly

proportional to the frequency of ac currents which isfed in the rotor winding.


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continue

This means that the rotating magnetic fieldpassing through the generator stator windings not

only rotates due to the rotation of the generator

rotor, but also due to the rotational effect

produced by the ac currents fed into thegenerator rotor windings.

Therefore, in a doubly-fed induction generator,

both the rotation speed of the rotor and the

frequency of the ac currents fed into the rotorwindings determine the speed of the rotating

magnetic field passing through the stator

windings, and thus, the frequency of the

alternating voltage induced across the stator


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Advantages of DFIG

Allows Extracting Maximum Energy from the windat low speed by optimizing the turbine speed and

while minimizing mechanical stress.

Ability to generate or absorb reactive power by

the help of power electronics converter.

It has four quadrant operation.

Speed Control and Reduced Flicker.

Improved system efficiency and improve powerfactor.


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Feature of VSC Based HVDC

System

Attractive an option for bulk power transmissionover long or short distances and grid integration

of renewable energy sources.

Maintain system voltage stability

It is self commutated

The polarity of DC transmission system remains

unchanged in the case of reversal of power.


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Benefits of VSC HVDC

Transmission System

Flexibility and controllability of the power flow.

Multi terminal configurations.

Fast response in case of disturbances. Possibility to control the reactive power

(consumed or generated by the converter)

independently of the active power (to or from the

converter). No risk of commutation failures in the converter.

Ability to connect to weak AC networks, or even

dead networks.


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Continue.

Faster response due to increased switchingfrequency (PWM).

Minimal environmental impact.

Transmission distance using DC is not affected

by cable charging currents.

Fewer cables are required and lower cable power

cable losses.


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Grid Side VSC and Wind farm

VSC


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Equivalent AC circuit of GSVSC


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Wind Farm VSC

Collect energy from Wind farm and transmits it tothe grid via two XLPE DC cable to the grid.

Controls the AC voltage and Frequency of the

WFVSC.

Provide Reactive power to the grid.

A high pass filter (HFF) is connected at each side

to absorb the high frequency harmonics

generated by the converters during operation Can not control DC voltage but Control AC

voltage.


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Control block Diagram of WFVSC


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Grid side VSC


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Grid side VSC

DC voltage controller.

Collect energy from WFVSC.


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Control Block Diagram of GSVSC


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References. Lie xu,Senior Member, IEEE,Liangzhong yao, and

christan sasse.

Principles of Doubly-Fed Induction Generators

(DFIG)-By lab volt.

S. Muller, M. Deicke, and R. W. De Doncker, Doublyfed induction generator systems for wind turbines,

IEEE Ind. Appl. Mag., vol. 8, no.3, pp. 2633,

May/Jun. 2002.

R. Pena, J. C. Clare, and G. M. Asher, Double fedinduction generator using back-to-back PWM

converter and its application to variable speed wind-

energy generation, Proc. Inst. Elect. Eng., Elect.

Power Appl., vol. 143, no. 3, pp. 231

241, 1996.


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THANK YOU.

integration of dfig wind generation

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