Superconducting Generators for Wind Turbines Advisor & Client Dr. James McCalley Abrahem Al-afandi Hamad Almutawa MajedAtaishi
Overview • Project Background. - What is it? • Why? • Objectives. • Approach Taken. • Suggested Designs. • Design Evaluation Methods.
Project Background • What is it? • Inland Direct-Drive Wind Turbines. • 5-MW PMSG. • 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
Objectives • Suggested 5MW turbine using permanent magnet generator. • Suggested 10 MW turbine using high temperature Superconductor generator. • Each suggested design has: • To be Cost-effective. • High Energy yield. • Low weight and volume. • Suitable cooling system.
Our Approach • Top to bottom view of steps taken : components & operation of Generator Direct-Drive vs. Conventional Feasible for 10-MW Feasible for 5-MW PMSG HTS Materials Different Topologies Materials Different Topologies Suggested Design 2 Suggested Design 1 Performance Attributes Performance Attributes Cost Analysis Cost Analysis Designs Evaluation
The Difference PMSG 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: • Low cost. • High reliability and availability. • 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. • Radial has relatively small diameter. • 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. VS. 2. 1. 3. VS. 4. VS. 6. 5.
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. 8. 7. VS. 9. 10. VS.
Two Possible PMSG Designs Axial-Longitudinal-Surface Mounted- Coreless- Slot-less Design 1 Design 2 Radial-Longitudinal-Surface Mounted-Iron core-Slotted • 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.
PMSG Materials • Three PM materials were investigated. Good Material to be used
2. HTS Topologies • Partially VS. fully superconductor. • Axial VS. Radial flux. • Air-core VS. Iron-core
Fully VS. Partially Fully Partially Partially is dominant until a breakthrough in AC losses is made
Axial VS. Radial Axial Radial Suitable for MW class
Air-core VS. Iron-core Air-core Iron core Promising if HTS price goes down Better performance
Recommended Design 1 • 5-MW PMSG wind Generator: Radial Inner-rotor Outer-rotor
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
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 the lowest cost/torque ratio. (good) This picture shows that RFPM has a relatively low Torque density.
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.
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:
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.