Transcript Superconducting Generators for Wind Turbines

Superconducting Generators
for Wind Turbines
Abrahem Al-afandi
Hamad Almutawa
Majed Ataishi
Advisor & Client
Dr. James McCalley
1
Overview
•
•
•
•
•
Project Background.
What is it?
Why?
Objectives.
Approach Taken.
Suggested Designs.
Design Evaluation Methods.
2
Project Background
 What is it?
• Inland Direct-Drive Wind
Turbines.
1. 5-MW PMSG.
2. 10-MW HTS.
 Why Direct-Drive?
• Integrated in nature.
• Avoiding the need for large,
maintenance-intensive gearbox.
• Reduced size and weight.
• Efficient & Reliable.
RPM
RPM
3
Objectives
• Suggested 5MW turbine using permanent magnet generator.
• Suggested 10 MW turbine using high temperature
Superconductor generator.

1.
2.
3.
4.
Each suggested design has:
To be Cost-effective.
High Energy yield.
Low weight and volume.
Suitable cooling system.
4
Our Approach
• Top to bottom view of steps taken :
components & operation of Generator
Direct-Drive vs. Conventional
Feasible for
5-MW
PMSG
Different
Topologies
Materials
Feasible for
10-MW
Different
Topologies
Materials
Suggested Design 2
Suggested Design 1
Performance
Attributes
HTS
Cost Analysis
Cost Analysis
Performance
Attributes
Designs Evaluation
5
The Difference
PMSG
HTS
Schematic
layouts
HTS is lighter
for higher MW
Cooling
Systems
6
Before Choosing Promising Designs
• There needs to be a balance among electrical, magnetic, thermal,
mechanical, and economic factors for a well designed generator.
• These factors are always conflicting with each other.
• No matter what kind of methods designers use to optimize, the keys are:
1. Low cost.
2. High reliability and availability.
3. High cost always prevents generators from commercialization.
In General, the better topology of DD generators has the
maximum output, minimum expenses and highest reliability.
1. PMSG Topologies
• Air Gap Orientation.
1. Radial has relatively small diameter.
2. Axial ha a compact design.
1.
VS.
2.
• Stator Core Orientation.
3. Longitudinal is used in conventional designs.
4. Transversal has less copper losses, diffi. To con.
3.
VS.
• PM Orientation with respect to air-gap.
5. Surface-Mounted PM is easer to construct.
6. Flux- concentrating PM has higher remnant flux.
4.
5.
VS.
6.
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1. PMSG Topologies Cont.
• Copper Housing.
7. Slotted has a better retention of the armature windings, but has cogging
torque.
8. Slot-less has low cogging torque.
8.
7.
VS.
• Iron Core VS. Coreless
9. Iron-Core has lamination losses and more weight.
10. Coreless eliminates cogging torque and reduce weight.
9.
10.
VS.
9
Two Possible PMSG Designs
Design 2
Design 1
•
Radial-Longitudinal-Surface
Mounted-Iron core-Slotted
Axial-Longitudinal-Surface
Mounted- Coreless- Slot-less
Inner-rotor
Outer-rotor
Outer-rotor
Double-rotor
Simple Construction
Accommodates multipole structure due to
larger rotor periphery.
Reduced weight due to
high no. of poles
Simple Stator
construction.
Good Utilization of
active materials
With stands
demagnetization
Reduced Yoke
thickness and
armature overhang.
Compact.
Relatively Smaller
diameter
Avoids the increase in
mass,
No Cogging torque
No vibrations
Less iron losses and
has a greater efficiency
Better torque density
•
Axial machines are not suited for MW power ratings,
since the outer radius becomes larger, and the mechanical
dynamic balance must be taken into consideration.
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PMSG Materials
• Three PM materials were investigated.
Good
Material
to be
used
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2. HTS Topologies
• Partially VS. fully superconductor.
• Axial VS. Radial flux.
• Air-core VS. Iron-core
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Fully VS. Partially
Fully
Strengths
Partially
Weaknesses
Highest power
density
High AC losses
Almost ½ the
mass of partially
SC
Complicated
cooling system
(needs high
power)
Smaller air-gap
Increase the use of
HTS> high cost.
Strengths
Weaknesses
Expected low AC
loss (Damper
shell)
Air-gap is
relatively
large(using
thermal Isolation
Low cost ( SC
only in field
winding)
Increased weight
Partially is dominant until a breakthrough
in AC losses is made
Rotating
sealing(only with
rotating field)
Axial VS. Radial
Axial
Radial
Strengths
Weaknesses
Strengths
Weaknesses
High power per unit
volume
Lower torque to mass
ratio
Suitable for MW DD
due to large diameter.
Lower torque to
volume ratio
Shorter than radial
Structurally unstable
when diameter is large
Widely used in wind
project. Simple
Compact
Heavier than radial
machines.
Mech. Structure easier
to be made stable
enough.
Suitable for
MW class
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Air-core VS. Iron-core
Iron core
Air-core
Strengths
Weaknesses
Strengths
Weakness
Popular for 10 MW SCDD
Reluctance in magnetic
circuit increases > more
HTS wires needed > high
cost
Less HTS wires>less cost
Presence of iron increases
rotor mass.
Better SC coil performances
& higher sync. Reactance.
Subject to eddy current
losses.
Reduce Weight
For 10KW>7.5km
For 100KW> 2.6 km
For stator: iron teeth brings
unwanted teeth harmonics.
Better transient stability
(sy. Reac. Smaller)
Higher peak torque and
current when short circuit
faults occur.
For stator: better cooling
scheme, no cogging
torque, small air gap flux
harmonics, reduce
vibration, better insulation
but causes cooling
difficulty
EMF acts directly on HTS
coils > limits performance.
For stator: possible to use
iron teeth with less losses
due to low freq. 10hz. Can
reduce cost of HTS
For Stator: Highly saturated.
Offers robust mechanical
support for armature
windings. Less comp
For Stator: Highly saturated.
Offers robust mechanical
support for armature
windings. Less complicated.
Less expensive.
For Stator: cogging torque.
Promising if
HTS price
goes down
Better
performance
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HTS Material
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Recommended Design 1
• 5-MW PMSG wind Generator:
Radial
Inner-rotor
Outer-rotor
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Recommended Design 2
•
•
•
•
•
10 MW SCDD Wind Generator:
Partially SC with HTS field winding on the rotor.
Stationary armature windings.
Radial flux machine.
Iron-cored rotor with iron teeth stator winding.
From
AMSC
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Performance Attributes
A good design
should not only
have high torque
density, but it
has to have a
low cost/torque
ratio.
Comparison table
This picture shows that RFPM has a
relatively low Torque density.
This picture shows that RFPM has the
lowest cost/torque ratio. (good)
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Cost Analysis Model
• Existing model From the National renewable energy lab.
• The purpose of the model is to calculate ICC, AOE.
• The Model is valid for:
1-Power range from 0.75MW - 5MW.
2-Rotor diameter: 80m-120m.
• It is valid for extrapolation for power
output up to 10MW and rotor diameter
of 200m.
Variables
For cost evaluation we need to get:
• AEP(Annual Energy production).
• ICC(initial capital cost).
• AOE(Annual operating expenses).
• FCR(Fixed charge rate).
• COE(Cost of Energy).
AEP
•
•
-
AEP = CF(capacity factor) * rated power * 8760 hours
The capacity factor varies depending on the wind farm.
AEP for 5MW generator is = 13.14GWh.
AEP for 10MW generator is = 26.28GWh.
The uncertainty percentage is:
+/- 0.02 for 5MW generator.
+/- 0.05 for 10MW generator.
Calculated Results
Generator
5 MW
10 MW
AEP
13140 MWh
26280 MWh
ICC (total)
5583.62k $
25510.96k $
AOE
145.4k $
290.6k $
COE
0.061 $/KWh
+/- 0.05
0.13 $/KWh
+/- 0.09
Design evaluation Methods
We were given 4 ways to evaluate our designs:
1- Evaluation using proper software. ✖
2- Hardware evaluation. ✖
3- Literature review. ✔
- Technical papers.
- IEEE articles and researches.
4- Industry experts. ✔
- AMSC(HTS).
- ABB & Gamesa(PMSG).
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Cost Analysis Evaluation
Validating AEP:
COE in $/KWh for different power
ratings and diameters:
Cost Estimation
Remarks
• Wind turbines are growing in
power capacity with each
new generation.
• Wind farm economics is
demanding increased
reliability to minimize cost and
maximize productivity.
• More power per tower.
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Question?
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