analysis of a 1.7 mva doubly fed wind-power induction generator during power systems disturbances...

Analysis of a 1.7 MVA Doubly Fed Wind-Power Induction Generator during Power

Systems Disturbances

Slavomir Seman, Sami Kanerva, Antero Arkkio

Laboratory of Electromechanics

Helsinki University of Technology

Jouko Niiranen

ABB Oy, Finland

HELSINKI UNIVERSITY OF TECHNOLOGYDepartment of Electrical and Communications Engineering

Overview

• Introduction

• The Doubly Fed Induction Generator

• Frequency Converter and Control

• Crowbar

• Modeling of The Network, Transformer and Transmission

Line

• Simulation Results

• Conclusions

Rs RrLsl Lrl

Lmus

j(k

r

r

im

irisjk

s

ur

The Doubly Fed Induction Generator

P N 1.7 MW

U N, stator (L-L) 690 V (delta)

U max, rotor 2472 V (star)

n N 1500 rpm

f N, stator 50 Hz

Transient Model of the Generator

• The machine equations x-y reference frame fixed with rotor

• Constant speed - no equation of movement included

Frequency Converter and Control

Model of the Frequency Converter

• Two back-to-back connected voltage source inverters (VSI)

• DTC

• The Network Side Converter - simplification 1-st order filter transfer function

• PI controller Udc -level

The Rotor Side Converter

Model of the Rotor Side Converter

• Modified DTC

• Input demanded PF or Q , Tref

• Voltage vector applied - optimal switching table

• The tangential component of the voltage vector controls the torque whereas the radial component increases or decreases the flux magnitude

Over-Current Protection - Crowbar

ra ra rb rb rc rc( i -i + i -i + i -i )/2crowI

maxdc dcU U

_crow crow crow CB semicU R I U

Passive Crowbar

• over-current protection - the rotor, rotor side converter

• no chopper mode

• disconnection of the converter rotor is connected to CB

• CB is active until MCB disconnects stator from the network

Modeling of the Network, Transformer and Transmission Line

Modelling of test set-up

• Power supply - SG or 3-phase V source with short circuit reactance and inductance

• Transmission line - R-L equivalent circuit

• Transformer - short circuit R-L and stray C, no saturation

• Short circuiting TR - R-L equivalent circuit

Simulation Results - Voltage Dip without Crowbar

Matlab-Simulink, t_step = 0.5e-7, T_ref =0.5 p.u., w_ref = 1.067 p.u., Voltage dip 35% Un

4.8 4.9 5 5.1 5.2 5.3 5.4-1.5

-1

-0.5

0

0.5

1

1.5

t [s]

vas

var

ud

c [

p.u

.]

Stator voltage A - phaseRotor voltage A - phaseDC-link voltage

Voltage dip applied MCB open

Simulation Results - Voltage Dip without Crowbar

4.8 4.9 5 5.1 5.2 5.3 5.4-2

-1

0

1

2

3

4

t [s]

ias

iar

T e [p.u

.]

Stator current A - phaseRotor current A - phaseElectromagnetic torque


Simulation Results - Voltage Dip with Passive Crowbar

4.8 4.9 5 5.1 5.2 5.3 5.4-1.5

-1

-0.5

0

0.5

1

1.5

t [s]

vas

var

ud

c [

p.u

.]

Stator voltage A - phaseRotor voltage A - phaseDC-link voltage


Matlab-Simulink, t_step = 0.5e-7, T_ref =0.5 p.u., w_ref = 1.067 p.u., Voltage dip 35% Un

Simulation Results - Voltage Dip with Passive Crowbar

4.8 4.9 5 5.1 5.2 5.3 5.4-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

2.5

3

t [s]

ias

ia r T e [

p.u

.]

Stator current A - phaseRotor current A - phaseElectromagnetic torque


• Transient behaviour of DTC controlled DFIG for wind-power

applications studied.

• The transient simulation results with and without crowbar were

compared.

• When the crowbar is implemented, the stator and rotor transient

current decay rapidly and rotor circuit is properly protected.

• Transient electromagnetic torque is reduced by means of crowbar but

oscillates longer than in case without crowbar.

Conclusions

analysis of a 1.7 mva doubly fed wind-power induction generator during power systems disturbances...

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