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Superconducting Generators for Wind Turbines. Advisor & Client Dr. James McCalley. Abrahem Al- afandi Hamad Almutawa Majed Ataishi. Overview. Project Background. - What is it? Why? Objectives. Approach Taken. Suggested Designs. Design Evaluation Methods . Project Background. - PowerPoint PPT Presentation
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Superconducting Generators for Wind
Turbines
Abrahem Al-afandiHamad Almutawa
Majed AtaishiAdvisor & ClientDr. James McCalley
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Overview• Project Background. - What is it?- Why?• Objectives.• Approach Taken.• Suggested Designs.• Design Evaluation Methods.
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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
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Objectives• Suggested 5MW turbine using permanent magnet generator.• Suggested 10 MW turbine using high temperature
Superconductor generator.
Each suggested design has:1. To be Cost-effective.2. High Energy yield.3. Low weight and volume.4. Suitable cooling system.
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Our Approach• Top to bottom view of steps taken :
components & operation of Generator
Direct-Drive vs. Conventional
PMSG HTS
Different Topologies
Suggested Design 1
Materials
Different Topologie
sMaterials
Suggested Design 2
Designs Evaluation
Feasible for 5-MW
Feasible for 10-MW
Cost Analysis
Cost Analysis
Performance Attributes
Performance Attributes
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The DifferencePMSG HTS
Schematic layouts
HTS is lighter for higher
MW
Cooling Systems
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.
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1. PMSG Topologies• Air Gap Orientation.1. Radial has relatively small diameter.2. Axial ha a compact design.
• Stator Core Orientation.3. Longitudinal is used in conventional designs.4. Transversal has less copper losses, diffi. To con.
• PM Orientation with respect to air-gap.5. Surface-Mounted PM is easer to construct.6. Flux- concentrating PM has higher remnant flux.
1.
2.
VS.
3.
4.
VS.
VS.5.
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.
• Iron Core VS. Coreless 9. Iron-Core has lamination losses and more weight.10. Coreless eliminates cogging torque and reduce weight.
VS.
7.
8.
9.
VS.
10.
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Two Possible PMSG Designs
Design 1Design
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• Radial-Longitudinal-Surface Mounted-Iron core-Slotted
Inner-rotor Outer-rotor
Simple Construction
Accommodates multi-pole structure due to larger rotor periphery.
Good Utilization of active materials
With stands demagnetization
Relatively Smaller diameter
Avoids the increase in mass,
Better torque density
Outer-rotor Double-rotor
Reduced weight due to high no. of poles
Simple Stator construction.
Reduced Yoke thickness and armature overhang.
Compact.
No Cogging torque No vibrations
Less iron losses and has a greater efficiency
Axial-Longitudinal-Surface Mounted- Coreless- Slot-less
• 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
Fully VS. Partially
Fully PartiallyStrengths 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 WeaknessesExpected low AC loss (Damper shell)
Air-gap is relatively large(using thermal Isolation
Low cost ( SC only in field winding)
Increased weight
Rotating sealing(only with rotating field)
Partially is dominant until a breakthrough in AC losses is made
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Axial VS. Radial
Axial RadialStrengths WeaknessesHigh power per unit volume
Lower torque to mass ratio
Shorter than radial Structurally unstable when diameter is large
Compact Heavier than radial machines.
Strengths WeaknessesSuitable for MW DD due to large diameter.
Lower torque to volume ratio
Widely used in wind project. Simple Mech. Structure easier to be made stable enough.
Suitable for MW class
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Air-core VS. Iron-core
Air-core Iron coreStrengths Weaknesses Popular for 10 MW SCDD
Reluctance in magnetic circuit increases > more HTS wires needed > high cost
Reduce Weight For 10KW>7.5km
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.
Strengths WeaknessLess HTS wires>less cost Presence of iron
increases rotor mass.
Better SC coil performances & higher sync. Reactance.
Subject to eddy current losses.
For 100KW> 2.6 km For stator: iron teeth brings unwanted teeth harmonics.
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 performan
ce
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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 AttributesA good design
should not only have high torque density,
but it has to have a low cost/torque
ratio.
This picture shows that RFPM has a relatively low Torque density.
This picture shows that RFPM has the lowest cost/torque ratio. (good)
Comparison table
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.
VariablesFor 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.
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
Calculated Results
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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).
Cost Analysis Evaluation
Validating AEP:
COE in $/KWh for different power ratings and diameters:
Cost Estimation
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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?