Superconducting Generators for Large Wind Turbines

Markus Mueller – Ozan Keysanmarkus.mueller@ed.ac.u

ko.keysan@ed.ac.ukInstitute for Energy

SystemsThe University of

Edinburgh24/11/2011

European Wind Energy Association

Wind Turbines: Constantly Growing

Offshore Wind Turbines

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

Limiting Factors for Large Wind Turbines

Nacelle Mass Overall

Reliability

www.upwind.eu

Reliability of Wind Turbines

Hahn, B., & Durstewitz, M. (2007). Wind Energy-Reliability of Wind Turbines.

~1MW, 1500 onshore turbines

Three Stage Gearbox + DFIG

http://www.repower.de/en/wind-power-solutions/wind-turbines/6m

RePower 6 MW, 12 rpm

PROS•Low power electronics cost•Mature technology•Off-the-shelf components

CONS•Gearbox cost & mass•Less Efficient•Gearbox failures

The Switch

3.8 MW, 21 rpm6.5 m diameter 81 tonnes

Direct Drive: PMG

PROS•Minimum Moving Parts•High Efficiency

CONS•Large Diameter•High Cost

6 MW, 13 rpm10 m diameter220 tonnes

Direct Drive: EESG

Enercon

PROS•Easier to manufacture•Reduced cost•Controllable field

CONS•Increased Mass•Brushes on rotor

www.enercon.de

Single Stage Gearbox + PMG

PROS•Reduced magnet cost•Reduced generator mass•High efficiency

CONS•Reduced reliability(?)•Gearbox Cost & Mass

Multibrid

WinWind 3MW

www.winwind.comwww.areva-wind.com

Areva 5MW

Direct-Drive Solutions

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

Direct-Drive Solutions

(*) D. Bang et.al. “Review of Generator Systems for Direct-Drive Wind Turbines,” 2008,

All data available at goo.gl/ZZivv

Power Applications

Courtesy of AMSC, InnoPower Superconductor

Transmission LinesHigh efficiency10 times more power from the same conduit area

Fault Current LimiterQuick responseReduced volumeCheaper to operate

Power Applications : Electrical Machines

Courtesy of Siemens, Converteam (ALSTOM)

Siemens: 400 kW

Converteam (ALSTOM): 5 MW HTS

(Smaller than the 2.5 MW Load Motor)

Power Applications : Electrical Machines

36.5 MW, 120 rpm Ship Propulsion Motor

Designed by AMSC for U.S. Navy

Courtesy of AMSC

75% More Power

40% Lighter

Reliability?

Cooling System Cryogenic Couplers Electric Brushes Transient torques on

SC AC losses on SC wire

Issues with Superconducting GeneratorsSeaTitan

AMSC, 10 MW, 10 rpm

Direct-drive superconducting generator

Stationary SC Coil No Cryogenic Coupler No Brushes No Transient Torque on

SC Simplified Cooling,

Isolation DC Field

No AC losses Maximized Current

Advantages of the Concept

Transverse Flux HTSG

Easy to build Modular Rotor Stationary SC coil Single SC winding

Minimal SC wire length

Simple cooling No torque on SC

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

Linear Prototype

Easy to build Modular Rotor Stationary SC coil Single SC winding

Minimal SC wire length

Simple cooling No torque on SC

Next Stage- Large Diameter Generator

Power density further increased

Two independent machines

Self-supporting structure

Easy to maintain SC

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.