Wind Turbine Modelling of a Fully-Fed Induction Machine...Wind Turbine Modelling of a Fully-Fed Induction Machine 97 4 open_looppwm 3 sync_pwm 2 unsync_pwm 1 discrete_pwm Uref P1 P2

4

Wind Turbine Modelling of a Fully-Fed Induction Machine

Umashankar S, Dr. Kothari D P and Mangayarkarasi P VIT University & Anna University

Tamilnadu, India

1. Introduction

This document provides detail about modelling Fully-Fed Induction Generator (FFIG) based

wind farm. The generator torque model was specified either as a constant derived from

nominal turbine power or pitch control block depends on the wind speed.

This model has been simulated under the normal operating condition and three different

fault conditions. The performance of the model analysed based on the speed, torque,

voltage, current, and power of generator, converter and grid.

This document contains the model design parameters and simulation results.

2. Wind farm model

The model in Fig.1. is the top level model of the fully-fed induction generator based wind

farm with the following subsystems:

1. Induction generator and its torque subsystem 2. Converter Bridges 3. Machine bridge control 4. Network bridge control 5. Pitch Controller 6. Transmission line and grid

2.1 Induction generator The Induction Generator block is a standard block in the SimPowerSystems Application

Library, Machines. Its design is based on reference 3

2.2 Converter bridges This is a standard block in SimPowerSystems, Power Electronics, Universal Bridge. The

pulses for these two bridges given from subsystems MCB control and NWB control, which

are modelled based on the vector control principles. Its design parameters are based on

reference 12. Source: Wind Power, Book edited by: S. M. Muyeen,

ISBN 978-953-7619-81-7, pp. 558, June 2010, INTECH, Croatia, downloaded from SCIYO.COM

www.intechopen.com

W

ind Power

94

Fig

. 1. To

p L

evel W

ind

Farm

Mo

del

TX LineGrid Park T/Xr

InterconnectingCable

WTbreaker

WTG T/XrWTG

Te, wm

Fault_block

View Scope To Plot

mech system

BR

DC LINK INVERTER

1

0

1

0

Grid_outputs

WTG_outputs

Inv_outputs

mec_outputs

results_scope

Grid_outputs

WTG_outputs

Inv_outputs

mec_outputs

results_plot

Discrete,

Ts = 5e-006 s.

pow ergui

A

B

C

a

b

c

Tm

m

A

B

C

Tm

com

A

B

C

a

b

c

com

A

B

C

a

b

c

A B C

A B C

A

B

C

A

B

C

Iinv

Conn1

Conn2

Measurements

A

B

C

m1

[Vdc]

[Wm_Te]

[Vdcref]

-K-

Gain

[mech_var][mech_var]

[inv_var][inv_var]

I_Inv

V_WTP1

I_Inv

[Wm]

I_WT1

[wtg_var][wtg_var]

[grid_var][grid_var]

Conn1

Conn2

Conn3

plot_en

Constant1

scope_en

Constant

IGabc

Wm

Vinv

Iinv

Vdcref

Vdc

inA

inB

inC

outA

outB

outC

A

B

C

a

b

c

A

B

C

a

b

c

A

B

C

a

b

c

A

B

C

a

b

c

A

B

C

a

b

c

A

B

C

a

b

c

A

B

C

a

b

c

A

B

C

a

b

c

<Electromagnetic torque Te (N*m)>

<Rotor speed (wm)>

ww

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95

Fig. 2. Wind Turbine Generator mask dialogue

MCB control NWB control

MCB NWB

2

Vdc

1

Vdcref

6

outC

5

outB

4

outA

3

inC

2

inB

1

inA

1100*pi/30

Wref

v+-

Vdc_ref

Vdc_actual

g

A

B

C

+

-

g

A

B

C

+

-

Saturation

Vabc

Iabc

Vdc_Ref

Vdc

pulse1

pulse2

pulse3

pulse4

IGabc

Wm

W*

pulses1

pulses2

pulses_mc

pulses_nw

1100

Constant2

4

Iinv

3

Vinv

2

Wm

1

IGabc

Fig. 3. DC link-Inverter with control blocks

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2.3 Machine-bridge This subsystem was modelled based on the vector control principles, in which the flux and

torque controlled with the use of speed controller and hysteresis current controller. All the

parameters are converted into two phase quantities and then the required flux and torque

are calculated using abc to dq conversion. Here one provision is also available for checking

the controller response for step change in speed.

2

openloop_pulse

1

clloop_pulsePhir

Te*Iq*

iqs*

calculation

Phir* Id*

id*

CalculationTeta

Id*

Iq*

Iabc*

dq to ABC

conversion

z

1

Phir

wm

Iq

Teta

Teta

Calculation

Speed

step

w

w*

Te*

Speed

controller

0.96

Phir*

[Speed]

Goto2

[Iabc]

Goto

[Iabc]

[Iabc]

[Speed]

[Speed]

IdPhir

Flux

Calculation

Pulses

Discrete

PWM Generator

Iabc

Iabc*

Pulses

Current

Regulator

109

Constant

speed

Iabc

Teta

Id

Iq

ABC to dq

conversion

3

W*

2

Wm

1

IGabc

Fig. 4. Machine bridge control block

2.4 network-bridge This subsystem was modelled based on the independent real and reactive power control

using voltage and current controller. All the AC quantities are converted into two phase dqo

and then the voltage and current references are estimated. Here one more provision is also

available to give different type of pwm pulses, open loop as well as closed loop.

2.5 Transmission line and grid specifications The transmission line is modelled as simple Π equivalent circuit block which is available

with the standard block in SimPowerSystems, Elements. Its design parameters are specified

in reference 8.

The Grid block is a standard block in the SimPowerSystems, Electrical Sources. Its design

parameters are based on reference 8. The grid condition is based on the parameters under

short-circuit section either by providing short-circuit power SCVA, Base Voltage Vrms, X/R

ratio SCR or by Source Resistance Rs and inductance Ls.

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4

open_looppwm

3

sync_pwm

2

unsync_pwm

1

discrete_pwm

Uref

P1

P2

unsynchronised 2L pwm

Uref

wt

P1

P2

synchronised 2L pwm

wt

VdVq

Vabc (t)

m_Phi->Vabc(t)

Vd

IdIq

IdIq_Ref

Vdc

VdVq

current Regulator

-K-

V->pu 1/z

Terminator3

Terminator2

Scope6

Scope3

Vabc (pu)

Freq

wt

Sin_Cos

PLL

v abc

sincos

Iabc

Vd

IdIq

Measurements

Pulses

Discrete

PWM Generator

Uref Pulses

Discrete

PWM

Vdcref

Vdcactual

Idref

DC Voltage regulator

0

-K-

A->pu

4

Vdc

3

Vdc_Ref

2

Iabc

1

Vabc

Fig. 5. Network bridge control block

Fig. 6. Transmission Line Π equivalent mask dialogue

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2.6 Pitch controller The pitch controller block is a standard SimPowerSystems Pitch Controller Library block. We have made some modifications to enable or disable the controller based on the wind speed. Also the existing standard wind turbine block will give the per unit torque value. Then this is converted into actual value by manually adding the gain block which multiplies it with the base torque.

2

Tm

1

m

Wind_On

Generator speed (pu)

Pitch angle (deg)

Wind speed (m/s)

Tm (pu)

Wind Turbine

PI

Rate Limiter

[pitch][Tm]

[Te]

[wr]-K-

Gain1

[pitch]

[Te]

[Tm]

[wr]

I_WT1

[wr]

V_WT1

Wind_On

0

Display9

Display8Display7

Display5

Display4

Display3

Display2

Display1

Vabc_B1

Iabc_B1

wr

Tm

Te

Pitch_angle (deg)

Pmes

m

Data acquisition

Pmec/Pnom

2

m1

1

Wind (m/s)

<Rotor speed (wm)>

<Electromagnetic torque Te (N*m)>

Fig. 7. Pitch controller block

Fig. 8. Wind Turbine mask dialogue

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0 0.2 0.4 0.6 0.8 1 1.2 1.4

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

1 pu

Max. power at base wind speed (12 m/s) and beta = 0 deg

6 m/s

7.2 m/s

8.4 m/s

9.6 m/s

10.8 m/s

12 m/s

Turbine speed (pu of nominal generator speed)

Turb

ine o

utp

ut

pow

er

(pu o

f nom

inal m

echanic

al pow

er)

Turbine Power Characteristics (Pitch angle beta = 0 deg)

Fig. 9. Wind Turbine characteristic curves

Run the M-file Turbine_model_initialisation.m first to assign values to Parameters

u(1)^3

wind_speed^1

-K-

pu->pu 1

-K-

pu->pu

-C-

pitch angle1

-K-

lambda_nom1

lambda

betacp

cp(lambda,beta)1

-C-

Wind speed

(m/s)2

-0.7356

Tm (pu)2

Product1

Product 1

-C-

Generator speed (pu)2

-1

0.8827

Display9

9.72

Display8

12

Display16

1.2

Display15

0.4237

Display14

1.2

Display13 0.8827

Display12

1

Display11

1.2

Display10

Avoid division

by zero1

Avoid division

by zero 1

-K-

1/wind_base1

-K-

1/cp_nom1

Pwind_puPm_pu

lambda

cp_pu

lambda_pu

wind_speed_pu

Fig. 10. Wind Turbine Block

3. Modelling notes and assumptions

The model is completely discrete; there are no continuous states. The model is full parameterised; it has no hard coded parameter values. All the model parameter values are set up in the initialisation file. The model could be used for a different wind turbine simply by changing the initialisation file; no change to the model is needed.

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Wind Power

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The stiffness of the shaft between the generator and wind turbine was chosen so that mechanical resonance occurred at 5Hz. This was done to demonstrate the effectiveness of active damping. MATLAB mechanical dynamic model has been made discrete. The sample time chosen for

the discrete model, 5X10-6 s, gave time domain results very close to the continuous model

for 5Hz resonant frequency.

The model assumes that the converter DC link voltage is maintained constant during the

simulations, thus the energy storage of the DC link due to the DC link capacitor has not

been modeled.

The standard MATLAB wind turbine model has been used, which is analytic but doesn’t completely agree with the data provided by client in reference 1. The wind speed is assumed to be rated value and hence the torque and speed of the generator. The wind turbine is considered to be delivering the power to grid and not to local loads. All the initial conditions are assumed to be zero, unless otherwise specified externally and losses neglected to make the model simple and calculation easier. As the objective of the modelling work was to get the correct transient response during a grid fault, generator and converter losses neglected or assumed to be zero. The model is not analysed under Grid Fault Ride through Conditions, also not able to maintain the stability due to unavailable provision for voltage stabilization.

4. Results

Simulation results are provided for the following different cases 1. Normal operation 2. Grid Fault Analysis

a. Three-Phase Line to Ground Fault b. Two-Phase Line to Line Fault

The following category figures are plotted for each scenario 1. Generator Voltage, Current, Real Power and Reactive Power 2. Generator Electromagnetic Torque, Speed 3. Mechanical Torque, Rotor and Wind Speed, Pitch 4. Inverter Voltage, current, PWM pulses, Vdc 5. Grid Voltage, Current, Real Power and Reactive Power

4.1 Normal operation To analyse the model under normal operating condition, follow the steps in the below

snapshot of the matlab command window. After the simulation, command window will

prompt for user input to display the results and to save the figures. To start with run the

main.m file in command window and follow the steps below:

4.1.1 Comments on the result At rated torque and speed, the FFIG delivers the rated power to grid under normal

operation. The negative sign in the generator power waveform denotes consumption and

positive sign denotes generation of power. Thus the generator delivering rated power to

grid by absorbing some reactive power.

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Fig. 11. Matlab command window as user interface, normal operation

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5-5000

0

5000Wind Generator Voltage in Volts

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5-1

0

1x 10

4 Wind Generator Current in Amps

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5-2

0

2x 10

7 Wind Generator Real Power in Watts

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5-2

0

2x 10

7 Wind Generator Reactive Power in vARs

Time in secs

Fig. 12. Generator-side electrical outputs, normal operation

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0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5-5

0

5x 10

4 Wind Generator Electro Mag Torque in N-m

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5-5

0

5x 10

5 Mech Torque in N-m

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 51000

2000

3000Wind Generator Speed in RPM

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5-1

0

1Pitch in °/sec

Time in secs

Fig. 13. Generator-side mechanical outputs, normal operation

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5-2000

-1000

0

1000

2000Inverter Voltage in Volts

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5-4

-2

0

2

4x 10

4 Inverter Current in Amps

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 50

1000

2000

3000DC Link Voltage Ref, Actual in volts

Time in secs

Fig. 14. Inverter Electrical outputs, normal operation

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4.995 4.9955 4.996 4.9965 4.997 4.9975 4.998 4.9985 4.999 4.9995 5-1

0

1

2Machine Bridge pulses

4.995 4.9955 4.996 4.9965 4.997 4.9975 4.998 4.9985 4.999 4.9995 5-1

0

1

2Network Bridge pulses

Time in secs

Fig. 15. PWM pulse outputs, normal operation

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5-2

0

2x 10

5 Grid Voltage in Volts

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5-1000

0

1000Grid Current in Amps

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5-5

0

5x 10

7 Grid Real Power in Watts

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5-2

0

2x 10

8 Grid Reactive Power in vARs

Time in secs

Fig. 16. Grid-side Electrical outputs, normal operation

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The negative sign in torque denotes it as generating torque. The real power is delivered to grid with some loss of power in the transformer, cable and transmission line. Fig.14. shows inverter output settles after one sec, before that there are some spikes occurring at regular intervals. This can be avoided by providing dv/dt filters in the output. The dc regulator maintains the dc voltage at its constant level as seen from fig.14. The PWM pulse output shown in fig.15. for both machine and network bridges. The modulation is unsynchronised sine pwm and it’s based on the closed loop bridge control.

4.2 Three-phase to ground grid fault To analyse the model under three-phase to ground grid fault condition, follow the steps in the below snapshot of the matlab command window. After the simulation, command window will prompt for user input to display the results and to save the figures. To start with run the main.m file in command window and follow the steps below:

4.2.1 Comments on the result At rated torque and speed, the FFIG delivers the rated power to grid under normal operation. At time t=2.5s, three-phase to ground fault is created at the grid side transmission line hence the grid current abruptly increased. The generator voltage, current will not become zero as like in fixed speed wind turbine and speed will increase above rated speed. Also the actual dc voltage becomes zero with that of reference.

Fig. 17. Matlab command window as user interface, 3phase grid fault

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2 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3-5000

0


2 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3-2

0

2x 10


2 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3-5

0

5x 10


2 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3-5

0

5x 10


Time in secs

Fig. 18. Generator-side electrical outputs, 3phase grid fault

2 2.2 2.4 2.6 2.8 3 3.2 3.4 3.6 3.8 4-5

0

5x 10


2 2.2 2.4 2.6 2.8 3 3.2 3.4 3.6 3.8 4-5

0

5x 10


2 2.2 2.4 2.6 2.8 3 3.2 3.4 3.6 3.8 41800

2000


2 2.2 2.4 2.6 2.8 3 3.2 3.4 3.6 3.8 4-1

0

1Pitch in °/sec

Time in secs

Fig. 19. Generator-side mechanical outputs, 3phase grid fault

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Wind Power

106

It is evident from the fig.19. that there is a mechanical torque reversal during the grid fault and there are some oscillations in all the waveforms after the fault has been cleared. But the shaft between generator and wind turbine will ring at its natural frequency. At time t=3s fault is cleared and all the quantities will slowly come to its previous condition of normal operation. Since electromagnetic torque becomes discontinuous during grid fault and initial conditions are changed after fault removal, it will take more time to settle in steady state. Implementation of GFRT will rectify this issue and stabilize the electrical parameters during fault and after fault removal.

2 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3-5000

0


2 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3-5

0

5x 10


2 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 30

2000


Time in secs

Ref

Actual

Fig. 20. Inverter Electrical outputs, 3phase grid fault

2.5 2.5005 2.501 2.5015 2.502 2.5025 2.503 2.5035 2.504 2.5045 2.505-1

0

1


2.5 2.5005 2.501 2.5015 2.502 2.5025 2.503 2.5035 2.504 2.5045 2.505-1

0

1


Time in secs

Fig. 21. PWM pulse outputs, 3phase grid fault

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2 2.5 3 3.5-1

0

1x 10


2 2.5 3 3.5-500

0


2 2.5 3 3.5-5

0

5x 10


2 2.5 3 3.5-5

0

5x 10


Time in secs

Fig. 22. Grid-side Electrical outputs, 3phase grid fault

Fig. 23. Matlab command window as user interface, 2phase grid fault

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2 2.5 3 3.5-5000

0


2 2.5 3 3.5-2

0

2x 10


2 2.5 3 3.5-5

0

5x 10


2 2.5 3 3.5-5

0

5x 10


Time in secs

Fig. 24. Generator-side electrical outputs, 2phase grid fault

2 2.5 3 3.5 4 4.5 5-1

0

1x 10


2 2.5 3 3.5 4 4.5 5-2

-1.5

-1x 10


2 2.5 3 3.5 4 4.5 51000

1100


2 2.5 3 3.5 4 4.5 58

10

12Wind Speed in m/s

2 2.5 3 3.5 4 4.5 5-1

0

1Pitch in °/sec

Time in secs

Fig. 25. Generator-side mechanical outputs, 2phase grid fault

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2 2.5 3 3.5-2000

0


2 2.5 3 3.5-5

0

5x 10


2 2.5 3 3.5-2000

0

2000


Time in secs

Ref

Actual

Fig. 26. Inverter Electrical outputs, 2phase grid fault

2.5 2.501 2.502 2.503 2.504 2.505 2.506 2.507 2.508 2.509 2.51-1

0

1


2.5 2.501 2.502 2.503 2.504 2.505 2.506 2.507 2.508 2.509 2.51-1

0

1


Time in secs

Fig. 27. PWM pulse outputs, 2phase grid fault

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2 2.5 3 3.5-2

0

2x 10


2 2.5 3 3.5-500

0


2 2.5 3 3.5-5

0

5x 10


2 2.5 3 3.5-1

0

1x 10


Time in secs

Fig. 28. Grid-side Electrical outputs, 2phase grid fault

4.3 Two-phase line to line grid fault To analyse the model under two-phase line to line grid fault condition, follow the steps in

the below snapshot of the matlab command window. After the simulation, command

window will prompt for user input to display the results and to save the figures. To start

with run the main.m file in command window and follow the steps below:

4.3.1 Comments on the result At rated torque and speed, the FFIG delivers the rated power to grid under normal

operation. At time t=2.5s, two-phase line to line fault is created at the grid side transmission

line hence the grid current abruptly increased. The generator speed will increase above

rated speed. Also the actual dc voltage maintained as that of reference.

It is evident from the fig.25. that there is a no mechanical torque reversal during the grid

fault but the torque tends to reduce and the oscillations in all the waveforms during grid

fault are not severe. Also the shaft between generator and wind turbine will ring at its

natural frequency.

At time t=3s fault is cleared and all the quantities will slowly come to its previous condition

of normal operation. Implementation of GFRT will rectify this issue and stabilize the

electrical parameters during fault and after fault removal.

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111

5. Conclusion and future work

The matlab model created for fully-fed induction generator based wind farm provides good

performance under normal and transient (fault) operating conditions. It provides good

results for different pwm techniques and fault conditions except the single-phase line to

ground fault, which should be verified with help of practical hardware scaled down model

or real time data from wind farms.

The present system also consist of machine and network bridge controllers in which the

former maintains dc link energy by controlling torque, speed and the later provides

controlled real, reactive power to grid.

The performance is achieved by considering assumptions mentioned in section (3), hence

this matlab model should be implemented for Grid Fault ride-through and the performance

should be evaluated by comparing the results. The system also requires a condition

monitoring algorithm to check for faults & to protect the equipments from malfunctioning

or damage and filters to arrest the spikes.

Also this model should be tested at different speeds above & below rated speed and

performance of pitch controller should be verified as an extension to this work.

6. References

T. Ackermann (Editor), “Wind Power in Power Systems”, John Wiley & Sons, Ltd, copyright

2005

V. Akhmatov, H. Knudsen, M. Bruntt, A.H. Nielsen, J.K. Pedersen, N.K. Poulsen, “A

dynamic Stability Limit of Grid-Connected Induction Generators”, IASTED,

Mabella, Spain, September, 2000

M.B. Bana Sharifian, Y. Mohamadrezapour, M. Hosseinpour and S. Torabzade, “Maximum

Power Control of Grid Connected Variable Speed Wind System through Back to

Back Converters”, Journal of Applied Sciences, Vol.8(23), 4416-4421, 2008

Divya, KC and Rao, Nagendra PS,”Study of Dynamic Behavior of Grid Connected Induction

Generators”, IEEE Power Engineering Society General Meeting, Denver, Colorado,

USA, Vol.2, 2200 -2205, 6-10 June, 2004

P. Kundur, “Power System Stability and Control”, EPRI, McGraw-Hill, Inc., Copyright

1994

Kim Johnsen, Bo Eliasson, “SIMULINK® Implementation of Wind Farm Model for use in

Power System Studies”, Nordic Wind Power Conference NWPC’04, Chalmers

University of Technology, Göteborg, Sweden, 1-2 March 2004

Øyvind Rogne, Trond Gärtner,” Stability for wind farm equipped with induction

generators”, Nordic PhD course on Wind Power, Smøla, Norway, June 5 - 11, 2005

Paulo Fischer de Toledo, Hailian Xie KTH, Kungl Tekniska Högskolan, ”Wind Farm in

Weak Grids compensated with STATCOM”, Nordic PhD course on Wind Power,

Smøla, Norway, June 5 - 11, 2005

J. Soens, J. Driesen, R. Belmans, “Generic Dynamic Wind Farm Model for Power System

Simulations,” Nordic Wind Power Conference NWPC’04, Chalmers University of

Technology, Göteborg, Sweden, 1-2 March 2004

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Wind Power

112

D. P. Kothari I. J. Nagrath, “Elecrtical Machines”, 3rd Edition, Tata McGraw-Hill, NewDelhi,

2004

D. P. Kothari I. J. Nagrath, “Modern Power System Analysis”, 3rd Edition, Tata McGraw-

Hill, NewDelhi, 2003

www.intechopen.com

Wind PowerEdited by S M Muyeen

ISBN 978-953-7619-81-7Hard cover, 558 pagesPublisher InTechPublished online 01, June, 2010Published in print edition June, 2010

InTech EuropeUniversity Campus STeP Ri Slavka Krautzeka 83/A 51000 Rijeka, Croatia Phone: +385 (51) 770 447 Fax: +385 (51) 686 166www.intechopen.com

InTech ChinaUnit 405, Office Block, Hotel Equatorial Shanghai No.65, Yan An Road (West), Shanghai, 200040, China

Phone: +86-21-62489820 Fax: +86-21-62489821

This book is the result of inspirations and contributions from many researchers of different fields. A wide verityof research results are merged together to make this book useful for students and researchers who will takecontribution for further development of the existing technology. I hope you will enjoy the book, so that my effortto bringing it together for you will be successful. In my capacity, as the Editor of this book, I would like to thanksand appreciate the chapter authors, who ensured the quality of the material as well as submitting their bestworks. Most of the results presented in to the book have already been published on international journals andappreciated in many international conferences.

How to referenceIn order to correctly reference this scholarly work, feel free to copy and paste the following:

Umashankar S., Kothari D. P. and Mangayarkarasi P. (2010). Wind Turbine Modelling of a Fully-Fed InductionMachine, Wind Power, S M Muyeen (Ed.), ISBN: 978-953-7619-81-7, InTech, Available from:http://www.intechopen.com/books/wind-power/wind-turbine-modelling-of-a-fully-fed-induction-machine

© 2010 The Author(s). Licensee IntechOpen. This chapter is distributedunder the terms of the Creative Commons Attribution-NonCommercial-ShareAlike-3.0 License, which permits use, distribution and reproduction fornon-commercial purposes, provided the original is properly cited andderivative works building on this content are distributed under the samelicense.

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