Superconducting Generators for Large Wind Turbines

Markus MuellerOzan Keysan – Joe Burchell

markus.mueller@ed.ac.uko.keysan@ed.ac.uk

Institute for Energy SystemsThe University of Edinburgh

19/03/2012

Motivation

BARD 5MWGlobal 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

www.upwind.eu

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

Enercon4.5 MW, 13 rpm220 tonnes

All data available at 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 GeneratorsSeaTitan

AMSC, 10 MW, 10 rpm

Direct-drive superconducting generator

Homopolar HTSG

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

Bipolar HTSG

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 Output

70 kW

Speed 100 rpm

Diameter 1.3 m

Axial Length 0.5 m

SC Wire Current

216 A

SC Wire Length

880 m

Next Stage: Linear Prototype

Next Stage: Linear Prototype

Some Publications "A Homopolar HTSG Topology for Large Direct-Drive Wind Turbines",

Keysan O., and Mueller M., 2011. IEEE Transactions on Applied Superconductivity, 21(5), 3523 - 3531. doi:10.1109/TASC.2011.2159005.

"Superconducting Generators for Renewable Energy Applications", Keysan O., and Mueller M., 2011, IET Renewable Power Generation Conference, Edinburgh.

"A Transverse Flux High-Temperature Superconducting Generator Topology for Large Direct Drive Wind Turbines", Keysan O., and Mueller M., 2011. Superconductivity Centennial Conference, 2011, Den Haag, The Netherlands.

THANKS