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Dynastore

Sponsored by the German BMWA under contract FKz.:0327305 I

Flywheel Mass Energy Storage withHTS Bearing – Development StatusW.-R. Canders, H.May, J.Hoffmann, P.Hoffmann, F.Hinrichsen, I.Koch,

D.Röstermundt

WCRE / Eurosolar International Conference on Renewable EnergyStorage

IRES I

Oct.30-31,2006, Gelsenkirchen, Germany

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Dynastore

Any stressed un-buffered

non-linear system is highly

susceptible to collapse

Imre Gyuk, Programm Manager, Energy StorageResearch, DOE

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DynastoreUNIPEDE Statistics (1995)

bis 100 ms 0,5 s 1 s3 s

20 s > 20 s

100

60 bis 100

30 bis 60

10 bis 30

111

68

12

6

10

13

38

12

6

10

12

20

42

10

1

1216

33 4

0

20

40

60

80

100

120

power failures per Year in Europe:

> 10 ms: 346> 100 ms: 209

> 3 s: 10

Interruption time

Num

ber o

f Out

ages

p.a

.

Volta

gesa

g %

In Germany:

55 failures per year, with 9,6 shorttimebreaks < 100 ms,

0,4 longtime breaks > 1 min

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Dynastore

Liberalisation and reduced reserves in power grids will cause increasing number of power failures

Increasing numbers of disperse and regenerative energysuppliers will affect the stability of the power grid

Increasing numbers of computer controlledmanufacturing processes leads to increasing sensitivityof customers against disturbances in the power grid

In consequence necessity to use energy storagesystems to maintain power quality

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Dynastore

A stable Grid with regenerative sources needs at least twotypes of energy storage:

Fast responding (msec .. sec) storages for transientstability and power quality

Slow responding systems (sec..min) for balancing thedifference between actual demand and actual production

In general the amount of stored energy corresponds withthe response time (fast responding systems have usuallysmall amounts of stored energy)

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DynastoreCharacterisation of storage systems

H2 tank+fuelcell, fossile fuel tank + thermal energyconverter (ICE, Gas Turbine..) Chem. batteries (PB-, NiCd-, Li-Ion, VaRedoxFlow, NaS)

chemical

Flywheelkinetic

Pumped hydro storageCompressed Air

Compressed Air (CAES)Spring Storage1)potential

Hot water, hot steam, molten SaltSolid body storage (Cowperstorage, rock, concrete etc.)

thermic

LTS-SMESHTS-SMES

magnetical

CapacitorSupercapacitor

electrical

longhrs ..day

mediummin .. hrs

ShortSec .. min

dischargetime

Type of Energy

1) In practical use for brakes only

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DynastoreFeatures of a flywheel storage

Fuel cellsPb-, NiCd-,

NaS-Battery

Supercapacitor

LTS-SMESHTS-SMES

Ppumped hydroCAESSteam-

storage

mag

netis

chchemischele

ktrisch

thermisch potentiell

•

•

•

•

•

SteelTitaniumGlass fiberAramid fiberCarbon fiber

•

•

•

•

•

High efficiency

High power density

Advantageous cumulatedEnergy consumption

Small stand by losses

High lifetime / Cycle Numbers

Flywheelstorage

kinet isch

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DynastoreGoals for a fast responding Flywheel energy storage system

Flywheel energy storage with rated power P = 2 MW

Ride through time 20 sec

Netto Energy content 11 kWh (Brutto : 14 kWh)

Minimum „Stand By“ Losses

Power quality and UPS

Peak shaving

Urban Traffic

Applications

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DynastoreThe dynastore consortium

High temperature superconductors

Mit Schwung

ins nächste Jahrtausend

Market leader

for large power supply systems

Piller GmbH

Electrical engineering

Institute for ElectricalMachines, Drives andTraction, TU Braunschweig

GmbH

Flywheel, Energy Converter,Inverter, HTSC-magnetic bearings

Power semiconductors

MaterialsResearch & Production

DLR e.V., BraunschweigInstitute for Structural Mechanics

CFRPand production technology

gGmbH, Göttingen

IPHT e.V., Jena

SuperConductors

Solvay GmbH

UtilitiesUser

Net

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Dynastore

High Temperature Superconductor(HTSC) Flywheel Bearings

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DynastoreComponent structure of a Flywheel with active / HTSL bearings

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DynastoreTypical properties of SMB, Summary of experiences with SMBs

HTSC bearings are specifically „soft bearings“, whichshould be operated above the critical speed

The low Eigenfrequency yields high running smoothness

Inherent damping is weak. External damping necessary

Superconducting bearings show a progressive characteristic and linearisation at the point of operation bythe gradient of the local hysteresis loop is possible

The frequency dependence of the properties are linear up to high frequencies, but additional effects due to eddycurrents may appear

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DynastorePrincipal bearing topologies of SMB

Inherent stability in radial and axial direction

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DynastorePrinciples of activation

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DynastoreHTS Bearing with 500 kg load capacity for a 4 MVA HTS Generator

SIEMENS

HTSC Bearing with movable sleeves for centric rotor position

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DynastoreAssessment of superconducting bearings for flywheels

ActivationSimple activation by vertical movement of the rotor into operation positionunder gravitySafetyno crash possible if proper designed (No EMC problems, no sensor failure) Long thermal time constant when cooling failsLossesNo stator losses, if smooth flux distribution is achievedno rotor losses except parasitic eddy current lossesEnergy consumption of the cryocooler increases the loss balance

ButLong cool down time necessaryActuators for Activation of bearing necessaryLong lifetime, low cost stirling-cryocoolers with sufficient power are underdevelopment but not yet available

For a continuous operating flywheel with high energy content HTSC bearings are preferable due to the safety aspects

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Dynastore

Design Principles of Flywheelsystems

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DynastoreMass loaded Flywheel with external Motor, Jp/Ja < 1

Flywheel for bus propulsionP = 150 kW, n = 40.000min-1, W = 2kWh

University of Austin, Texas,

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DynastoreFeatures of mass loaded flywheel

Shaft with bearings on small diameter,

Active bearings with small gap and reduced losses

Heavy construction with high amount of fiber material

Low energy density

Jp/Ja < 1

Requires bearings of high stiffness and damping

Suitable for high rpm designs together with AMBs

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DynastoreStator, Rotor and cooling conductors assembly

Rimmed Flywheel

CFRP Rim

Hub with CFRP

reinforcement

Couplingstructure

HTS Bearing

Stator of Motor/Generator

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DynastoreHub – rim construction with integrated machine and bearings

Compact in size because machine and bearings areintegrated into the rotor bore

Low weight, main portion of energy is stored in the rim

Differences in elastic deformation between hub and rimcompensated by a patented novel radial elastic couplingstructure providing structural Eigenfrequencies far awayfrom the rotational frequency

Bearings with large active surface possible

Jp/Ja > 1,5

Suitable for high circumferential speeds with SMBs

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Dynastore

Examples ofactual Flywheel Designs

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DynastorePowerbridge, Piller Power Systems, 4.6 kWh, 14 sec

Technische Daten:Stored energy 16.5 MWsRated power 1650 kVASpeed 1800 bis 3300 rpmtotal weight 6000 kgRotorweight 2900 kgNo load losses 10 kWBearing regreasing 6 monthsBearing lifetime 8 years

Features:- Helium atmosphere- Magnetic load control- Redundant bearings

lift magnet

upper bearing

Up. aux. bearing

exciter machine

main Engine

flywheel

lower bearinglower aux. bearing

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DynastoreVYCON / Calnetix, Ca. ,125 kW, 12 sec, 0.4 kWh

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DynastoreBoeing Phantom works, 100 kW, 4 kWh, 2.4 min

HTSC bearing

Hub

Motor/Generator

Composite Rotor

Lift bearing

Vacuum vessel withenergy absorbing liner

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DynastoreExperimental Flywheel assembly with vacuum container

11 kWh,

2 MW, 20sec

10000 rpm

Minimal standbylosses

Response time2 msec

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Dynastore

Actual state of experimental setup

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DynastoreStructure of redundant power and control electronics

Customer

Brake choppers

Flywheel withdouble machine

GridGrid failure

Rect. control

ControlWR 2

ControlWR 1

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DynastoreInverter and control cabinet (4 MVA inverter)

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DynastoreVacuum vessel for the test setup

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DynastoreCentral mechanical hub structure

Bearing hubs

Motor/Generator hub and water jacket

958 mm

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DynastoreStatorwinding of the SRM hub drive

Central Hub and water jacket

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DynastoreApplication of the safety sleeve on the HTSL Bearing

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Dynastore

Conclusion

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Dynastore

The Dynastore Flywheel energy storage projectaims at transient stability of power grids and urban traffic applications

The development of the basic technologies and the design phase are finished

The production of the parts and the assembly of the flywheel and the bearings are in progress

The power electronics and control cabinets arealready finished and pretested

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DynastoreComparison of technologies

CoventionalFlywheeel„Powerbridge“

Dynastore

Usable Energy 4 kWh 11kWh

Rated Power 1200 kW 2000 kW

Efficiency

Stand By Losses

0,93

10 kW

0,94

1 kW

Mass 7000 kg 1200 kg

Dimensions D = 1500 mmH = 2000 mm

D = 1500 mmH = 600 mm

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Dynastore

Thank you for your attention