en wind turbine generators 2009

7/31/2019 En Wind Turbine Generators 2009

1/22

1

GTZ-TERNA Expert Workshop 2009: Grid and System Integration of Wind Energy, 10.11.2009-12.11.2009, Berlin/Germany

Wind Turbine Generators (WTGs) Physical Principles and Generator Concepts

Markus Pller and Oscar Amaya/DIgSILENT GmbH


Wind Energy Conversion


2/22

2


Wind Energy Conversion - Basics

Kinetic Energy Rotational Energy Electrical EnergyTurbine Generator

Generator


Wind Energy Converstion - Basics

Power extracted by wind turbine:3

2

1wpw AvcP =

A


3/22

3


Wind Energy Conversion - Basics

Ideal value 593.0max =pc

One bladeTwo blades

Three blades

Darrieus

Dutch-Type

American


Summary

Power in the wind increases with vw3

Power is proportional to swept area A, hence increases quadraticallywith increasing rotor diameter

Power coefficient depends on

Wind speed

Rotor speed

Number of blades

Blade design

Blade angle


4/22

4


Turbine Control Concepts


Aerodynamics

vt=R

vr

Fd

F

vw

Fl


5/22

5


Stall

>krit

vw

vt=R

vr


Pitching

vw

vr

vt=R

Fl


6/22

6



Stall Control:

Passive Stall:Power of the wind turbine is limited by the aerodynamic characteristicsof the turbine.

Active stall:Power of the wind turbine is limited additionally by decreasing the pitchangle (increasing the inflow angle).

Pitch Control:

Power of the wind turbine is limited by increasing the pitch angle(decreasing the inflow angle)



Stall Control:

Cost effective

Fast limitation of active power

Fixed speed operation possible

Pitch Control:

Accurate power control possible

Variable speed operation required


7/22

7


Wind Turbine Operation

Start

T

r

v

R=

Fix speed

Variable speed

P=Prated


Operation of Fix Speed Wind Turbine (passive stall)

Start up (with open breaker) if wind speed > cut-in wind speed

Close breaker

Operation at constant blade angle over the whole wind speed range

In case of large wind speeds: Power limited by aerodynamic profile.


8/22

8


Operation of Variable Speed Wind-Turbines

Start up (with open breaker) if wind speed > cut-in wind speed

Close breaker

Below rated wind-speed Maximum power coefficient (Max. Power Tracking) Evt: Speed Limitation

Above rated wind-speed: P=Prated (Limited by power electronics converter)

Pitching

Advantages of variable speed operation: Lower cut-in wind speeds Higher efficiency, especially at low wind speeds Lower power variations (compared to fixed speed turbines)

Disadvantage: More expensive!


Wind Turbine Operation Typical Power Curves

passive stall

Variable speed/pitch

kW

v


9/22

9

Generator Concepts


Fixed Speed Induction Generator


10/22

10


Induction Generator

1.201.161.121.081.041.00

3.00

2.00

1.00

0.00

-1.00

x-Axis: GWT: Speed in p.u.

GWT: Electrical Torque in p.u.

1.201.161.121.081.041.00

0.00

-2.00

-4.00

-6.00

-8.00


GWT: Reactive Power in Mvar

DIgSILENT


Induction Generator

1.041.031.021.011.00

3.00

2.00

1.00

0.00

-1.00



Constant Y = 1.000 p.u.1.008 p.u.

1.041.031.021.011.00

0.00

-1.00

-2.00

-3.00

-4.00

-5.00

-6.00


GWT: Reactive Power in Mvar

Constant X = 1.008 p.u.

-1.044 Mvar

DIgSILENT


11/22

11


Induction Generator LVRT-Bahaviour

Induction generator response to a weak voltage dip

0.600.400.200.00 [s]

1.20

1.00

0.80

0.60

0.40

0.20

0.00

G\HV:Voltage,Magnitude inp.u.

MV:Voltage,Magnitudeinp.u.

0.600.400.200.00 [s]

80.00

40.00

0.00

-40.00

-80.00

-120.00

Cub_0.1\PQPCC:ActivePowerinp.u.

Cub_0.1\PQPCC:ReactivePowerinp.u.

0.600.400.200.00 [s]

1.06

1.04

1.02

1.00

0.98

GWT:Speed

DIgSILENT


Induction Generator LVRT Bahaviour

Induction generator response to a strong voltage dip

2.001.501.000.500.00 [s]

1.20

1.00

0.80

0.60

0.40

0.20

0.00

G\HV:Voltage,Magnitude inp.u.

MV:Voltage,Magnitude inp.u.

2.001.501.000.500.00 [s]

80.00

40.00

0.00

-40.00

-80.00

-120.00

Cub_0.1\PQ PCC:Active Powerin p.u.

Cub_0.1\PQ PCC:Reactive Powerinp.u.

2.001.501.000.500.00 [s]

1.06

1.04

1.02

1.00

0.98

GWT:Speed

DIgSILENT


12/22

12


Induction Generator - Summary

Only fix speed operation possible (stall control required)

Reactive power compensation required

No reactive power control capability. Additional devices required:

TSCs (Thyristor switched capacitors)

STATCOMs

Risk of dynamic voltage collapse

> Typically, wind generators based on induction generators are asked todisconnect in case of voltage dips


Induction Generator with Variable Rotor Resistance

Grid

Gear Box

IG


13/22

13


Induction Generator with Variable Rotor Resistance

1.2001.1601.1201.0801.0401.000

3.00

2.00

1.00

0.00

-1.00





ConstantY

=

1.0

00p.u.

DIgSILENT

Rotor Resistance


Induction Generator with Variable Rotor Resistance - Summary

Simple concept for variable speed operation.

Reactive power compensation required.

No reactive power control capability. Additional devices required:

TSCs (Thyristor switched capacitors) STATCOMs

Limited LVRT capability. Dynamic voltage collapse problems have tobe mitigated by:

Fast increase of rotor resistance during faults

Additional reactive power compensation devices (typically TSCs)


14/22

14


Doubly-Fed Induction Generator


Doubly-Fed Induction Generator

su

sr

sx

mx

rx

rr

ru

si

ritj re

:1


15/22

15


DFIG-Control and Protection

P-I

P-I P-I

P-I

md mq md mq

id

iq

id

iq

QV

Ptot

Qtot

idref iqref idref iqref

Pref Qref Vref Qref

rotor-side

converter

grid-side

converterCrow-bar Chopper

Blocking


0

0,2

0,4

0,6

0,8

1

1,2

-1,2 -0,8 -0,4 0 0,4 0,8 1,2Q/Sn

P/Sn

Pn

Doubly-Fed Induction Generator Reactive Capability

Theoretical characteristicConst. cos(phi)-characteristicConst. Q-characteristic

with contributionfrom Grid-Side Converter

Limited by rotor-side converter

Limited by stator current/step-up transformer rating


16/22

16


Doubly-Fed Induction Generator LVRT-Behaviour

DFIG response to a weak voltage dip

0.600.400.200.00 [s]

75.00

50.00

25.00

0.00

-25.00

-50.00

-75.00

Cub_1\PCC PQ:Active Powerinp.u.

Cub_1\PCC PQ:Reactive Powerin p.u.

0.600.400.200.00 [s]

1.20

1.00

0.80

0.60

0.40

0.20

HV:Voltage,Magnitude inp.u.

MV:Voltage,Magnitude inp.u.

0.600.400.200.00 [s]

1.275

1.250

1.225

1.200

1.175

1.150

G1d:Speed

DIgSILENT


Doubly-Fed Induction Generator LVRT-Behaviour

DFIG response to a strong voltage dip (crow-bar operation)

2.001.501.000.500.00 [s]

75.00

50.00

25.00

0.00

-25.00

-50.00

-75.00

Cub_1\PCCPQ:ActivePowerinp.u.

Cub_1\PCCPQ:ReactivePowerinp.u.

2.001.501.000.500.00 [s]

1.20

1.00

0.80

0.60

0.40

0.20

HV:Voltage,Magnitudeinp.u.

MV:Voltage,Magnitudeinp.u.

2.001.501.000.500.00 [s]

1.275

1.250

1.225

1.200

1.175

1.150

G1d:Speed

DIgSILENT


17/22

17


Generator with Fully Rated Converter

SG/IG


Generator with Fully Rated Converter/Direct Drive

SG/IG


18/22

18


Generator with Fully Rated Converter Reactive Capability

Theoretical characteristicConst. cos(phi)-characteristicConst. Q-characteristic

0

0,2

0,4

0,6

0,8

1

1,2

-1,2 -0,8 -0,4 0 0,4 0,8 1,2Q/Sn

P/Sn

Pn

Converter current limit


Converter Driven Synchronous Gen

FCD response to a weak voltage dip (ideal DC-chopper)

0.600.400.200.00 [s]

60.00

40.00

20.00

0.00

-20.00

Cub_1\PCC PQ:Active Powerin p.u.

Cub_1\PCC PQ:Reactive Powerinp.u.

0.600.400.200.00 [s]

1.20

1.00

0.80

0.60

0.40

0.20


MV BusBar:Voltage,Magnitude inp.u.

0.600.400.200.00 [s]

1.15

1.10

1.05

1.00

0.95

0.90

Generator:speed

DIgSILENT


19/22

19


Converter Driven Synchronous Gen

FCD response to a strong voltage dip (ideal DC-chopper)

0.600.400.200.00 [s]

60.00

40.00

20.00

0.00

-20.00

Cub_1\PCC PQ:Active Powerinp.u.

Cub_1\PCC PQ:Reactive Powerin p.u.

0.600.400.200.00 [s]

1.20

1.00

0.80

0.60

0.40

0.20


MV BusBar:Voltage,Magnitude inp.u.

0.600.400.200.00 [s]

1.15

1.10

1.05

1.00

0.95

0.90

Generator:speed

DIgSILENT


Directly Coupled Synchronous Generator withVariable Gear Box

Variable speedGearbox


20/22

20


Synchronous Generator Reactive Capability

Reactive Capability

0

0,2

0,4

0,6

0,8

1

1,2

-1,2 -0,8 -0,4 0 0,4 0,8 1,2Q/Sn

P/Sn

Pn

Excitation current

Stator current


Voltage Dip Different Generator Concepts

1.251.000.750.500.250.00 [s]

1.10

1.00

0.90

0.80

0.70

HV: u[p.u.], SynG (conventionalpower plant)

MV: u[p.u.], SynG (conventionalpower plant)

1.251.000.750.500.250.00 [s]

1.10

1.00

0.90

0.80

0.70

HV: u[p.u.], DFIG

MV: u[p.u.], DFIG

1.251.000.750.500.250.00 [s]

1.10

1.00

0.90

0.80

0.70

G\HV: u[p.u.], IG

MV: u[p.u.], IG

1.251.000.750.500.250.00 [s]

1.10

1.00

0.90

0.80

0.70

HV: u[p.u.], CDS

MVBusBar: u[p.u.], CDS

DIgSILENT


21/22

21


Voltage Dip Different Generator Concepts

1.251.000.750.500.250.00 [s]

60.00

40.00

20.00

0.00

-20.00

-40.00

Cub_0.1\PQ PCC: P [MW], IG

Cub_0.1\PQ PCC: Q [Mvar], IG

1.251.000.750.500.250.00 [s]

80.00

60.00

40.00

20.00

0.00

-20.00

Cub_1\PCC PQ: P [MW], SynG (conventionalpower plant)

Cub_1\PCC PQ: Q [Mvar], SynG (conventionalpower plant)

1.251.000.750.500.250.00 [s]

60.000

40.000

20.000

0.000

-20.000

-40.000

Cub_1\PCC PQ: P [MW], DFIG

Cub_1\PCC PQ: Q [Mvar], DFIG

1.251.000.750.500.250.00 [s]

60.000

40.000

20.000

0.000

-20.000

-40.000

Cub_1\PCC PQ: P [MW], CDS

Cub_1\PCC PQ: Q [Mvar], CDS

DIgSILENT


Wind-Generator Concepts

InductionGenerator

Induction

Generator

InductionGenerator with

Variable RotorResistance

(Opti-slip) DFIG

Fixed Speed Variable Speed

Active StallStall Q-controlNo Q-control

Fully ratedconverter

No Q-control Q-control

SG


22/22


Thank You

Markus Pller Oscar Amay

[email protected] [email protected]

DIgSILENT GmbH

Heinrich-Hertz-Str. 9

72810 Gomaringen

www.digsilent.de

en wind turbine generators 2009

Documents