Superconducting Generators for Large Wind Turbines Markus Mueller Ozan Keysan – Joe Burchell Institute for Energy Systems The University of Edinburgh 19/03/2012

Motivation BARD 5MW Global Offshore Wind Energy Markets and Strategies,2009 In 2020, 85% of offshore wind turbine installations will be larger than 5 MW

Wind Turbines: Constantly Growing  How big?  UpWind Project: A 20 MW Wind Turbine is Feasible

Mass of Direct-Drive Generators Harakosan 1.5MW,18 rpm,47 tonnes (*) D. Bang et.al. “Review of Generator Systems for Direct-Drive Wind Turbines,” 2008, All data available at goo.gl/ZZivv goo.gl/ZZivv Enercon 4.5 MW, 13 rpm 220 tonnes

All data available at goo.gl/ZZivv goo.gl/ZZivv Mass of Direct-Drive Generators

Reliability of Wind Turbines Hahn, B., & Durstewitz, M. (2007). Wind Energy-Reliability of Wind Turbines. ~1MW, 1500 onshore turbines

Types of HTS Machines  Rotating DC Superconducting Field  Most Common Type  Transient Torques on HTS wire  Cryocooler Coupler + Electrical Brushes  Low Reliability + Maintenance  Magnetized Bulk HTS  Very Difficult to Handle  Demagnetization?  All Superconducting Machines  AC Losses on HTS wire

Reliability?  Cooling System  Cryogenic Couplers  Electric Brushes  Transient torques on SC  Demagnetization for Bulk SC  AC losses on SC wire Issues with Superconducting Generators SeaTitan AMSC, 10 MW, 10 rpm Direct-drive superconducting generator

Homopolar HTSG

 Pros  Stationary SC Field  No Brushes  No Transient Torque on SC  Simplified Cooling, Isolation

Homopolar HTSG  Cons  Uni-directional flux density  Reduced power density

Bipolar HTSG

 Pros  Bidirectional Flux  Increased Power Density  Cons  Double SC field winding  Mechanical Issues

Transverse Flux HTSG

 Pros  Single Stationary SC Coil  Bidirectional flux  High Torque Density  Cons  Magnetic Attraction Forces  3D Flux (Soft magnetic composites needed) Transverse Flux HTSG

3D FEA Verification

Main Specifications Power Output70 kW Speed100 rpm Diameter1.3 m Axial Length0.5 m SC Wire Current216 A SC Wire Length880 m

Next Stage: Linear Prototype

Some Publications  "A Homopolar HTSG Topology for Large Direct-Drive Wind Turbines", Keysan O., and Mueller M., IEEE Transactions on Applied Superconductivity, 21(5), doi: /TASC A Homopolar HTSG Topology for Large Direct-Drive Wind Turbines  "Superconducting Generators for Renewable Energy Applications", Keysan O., and Mueller M., 2011, IET Renewable Power Generation Conference, Edinburgh.Superconducting Generators for Renewable Energy Applications  "A Transverse Flux High-Temperature Superconducting Generator Topology for Large Direct Drive Wind Turbines", Keysan O., and Mueller M., Superconductivity Centennial Conference, 2011, Den Haag, The Netherlands.A Transverse Flux High-Temperature Superconducting Generator Topology for Large Direct Drive Wind Turbines THANKS