Lesson no16 application of Induction Generator in Wind.ppsx

IG Applications in Wind

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Lesson 16: Asynchronous
Generators/Induction Generators
ET 332b
Ac Motors, Generators and Power
Systems
1

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Learning Objectives
2
After this presentation you will be able to:
Explain how an induction generator operates
List application for induction generators in the use
renewable resources
Discuss the limitations of induction generators
Compute the power developed from an induction
generator using the per phase circuit model

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Induction Generators
Driving an induction motor faster than synchronous speed
when connected to the grid results in active power
generation
Induction generators (asynchronous generators) designed
with lower rotor R to reduce losses and machine slip.
Applications: Wind Turbines, Hydraulic Turbines (small
scale hydro), Gas engines fueled by
natural gas or biogas
cogeneration

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Induction Generator Starting SequenceInduction
Generator
Breaker
Prime
Mover
Mechanical
Power In
Generator
Losses
Electric
Power
Out
nr >ns
Existing Three Phase System
1.) Breaker open
2.) Increase prime mover
mechanical power input
until n
r>n
s.
3.) Close Breaker
4.) Adjust mechanical power
input to match electric
load.
P
mech=P
e+P
loss
Induction generator can
not vary terminal voltage
or frequency. Set by
system.

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Induction Generator Speed Power Curves05001000150020002500300035004000
-100
-50
0
50
100
Induction Machine Speed-Power Curve
Rotor Speed (rpm)
Air Gap Power
(
kW
)
ns
1.1ns
Generator
Operation
Pushover
Power

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Limitations of Induction Generations
•Require existing power grid for synchronous
operation.
–Can not control frequency or voltage independently
•Can not operate above pushover speed
•Require a source of reactive power to operate
–When connect to grid, system supplies reactive power
to operate generator
•When operating without grid connection
frequency varies with power output.
–Parallel capacitors supply reactive power

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Induction Generator Example
A three-phase, six-pole, 460 V, 60 Hz induction generator operates on
a 480 V system. The generator its rated power output is 20 kW. It
is driven by a turbine at a speed of 1215 rpm. The generator has
the following electrical parameters:
R
1=0.200 W, R
2= 0.150 W, R
fe= 320 W,
X
1=1.20 W, X
2=1.29 W, X
M=42.0 W
Find the active power delivered by the generator and the reactive
power it requires from the system to operate.

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Example Solution

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Example Solution

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Example Solution

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Example Solution

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Isolated Operation of Induction GeneratorsInduction
Generator
Breaker
Prime
Mover
Mechanical
Power In
Generator
Losses
Electric
Power
Out
nr >ns
Isolated Three Phase System
Reactive
Power from
Capacitors
When nr = ns, no
power delivered
Isolated Induction generator
requires residual flux
to build voltage
Capacitors supply reactive
power to load and
generator when voltage
builds.
Voltage falls rapidly when
load is applied.

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Voltage Build-up in Isolated Induction GeneratorsR1
-jXc
R2/s
jX2
jX1
jXm Rfe
Vin Current
Voltage
Iop
Vop
Xc0
Xc1
Xc0>Xc1 








fV
I
C
I
V
X
op
op
op
op
c
2
1
External Capacitor provides
Reactive power for operation
Operating point set by intersection
between magnetization curve and
X
c

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Voltage Build-up in Isolated Induction Generators
Lab measurements determine the magnetization curveThree Phase Induction Motor Magnetization Curve
0
20
40
60
80
100
120
140
0.00 0.25 0.50 0.75 1.00 1.25 1.50
Stator Current (A)
Stator Voltage (V)
Lab Data Linearized Magnetization CurveLoad Line F 28.45or F 10845.2C
602
1
110
1.18
f2
1
V
I
C
5
op
op

















Inductance
change
due to rotor
motion

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Voltage Build-up in Isolated Induction Generators
Single phase motor magnetization curveMagnetization Curve-Single Phase Motor
0.00
20.00
40.00
60.00
80.00
100.00
120.00
140.00
0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00
Current (A)
Voltage (V)
Lab Measurements Linearized Data Load Line F 127or F 1027.1C
602
1
120
5.74
f2
1
V
I
C
4
op
op


















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END LESSON 16: ASYNCHRONOUS
GENERATORS/INDUCTION
GENERATORS
ET 332b
Ac Motors, Generators and Power Systems
16