A design concept for large superconducting alternators

Kirtley, James L.; Furuyama, M.

doi:10.1109/t-pas.1975.31963

Cited by 21 publications

(5 citation statements)

References 8 publications

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“…Finally, a comment on the influence of the environmental shield. (8). This improvement is unfortunately cancelled by the increase in Boo due to the magnetic shield.…”

Section: Are Shown Inmentioning

confidence: 99%

“…The two-dimensional, 'infinite length' assumption means that 8 The solutions for the arbitrary constants contain K a, which is known, and K 1 and K 2, which are not. The two-dimensional, 'infinite length' assumption means that 8 The solutions for the arbitrary constants contain K a, which is known, and K 1 and K 2, which are not.…”

Section: Appendixmentioning

confidence: 99%

“…To protect the field winding from electromagnetic transients excited by changes in armature currents, a screening system is required and the preferred form of this is a double concentric screen rotating with the superconducting winding [a, 2,8]. To protect the field winding from electromagnetic transients excited by changes in armature currents, a screening system is required and the preferred form of this is a double concentric screen rotating with the superconducting winding [a, 2,8].…”

Section: Introductionmentioning

confidence: 99%

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The behaviour of screening systems in the superconducting a.c. generator

Miller

1977

Archiv f. Elektrotechnik

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Contents C'K A simple model is used to analyse the screening properties and interactions of both single and double cylindrical screens in the superconducting alternator. It is shown that interaction with a closed field winding can seriously degrade the screening effectiveness. A simple technique is described for estimating the direct and quadrature axis time constants required in the 'heteropervious' screen proposed by the author. ObersichtEs wird ein einfaches Modell benutzt, um die Schirmeigenschaften und die Wechselwirkungen sowohl yon Einzel-als auch yon Doppelabschirmzylindern im Turbogenerator mit supraleitender Erregerwictdung zu analysieren. Es stellt sich heraus, dab Wechselwirkung bei geschlossener Erregerwicklung die Schirmleistung sehr beeintrAchtigen kann. Ein einfaches Verfahren wird beschrieben, um die Liings-und Querachsen-Zeitkonstanten abzusch~tzen, die ffir den vom Yerfasser vorgeschlagenen asymmetrischen (,,heteropervious") Schirm erforderlich sind. List of SymbolsNd, Nq f J S(f) T T t E magnetic vector potential, Wb[m magnetic flux density, T peak value of sine-distributed flux-density: radial and circumferential components, T normalised flux-density permeability of free space, H/m resistivity, ~m thickness of screen, m radian frequency, rad/s double screen interaction factor number of pole-pairs d-and q-axis armature currents number of effective turns on d-and q-axis armature coils frequency, Hz V:S screening-ratio frequency-response function time constant, s time constant as reduced by closed field winding, S electric field strength, Vim R L c~, c~ -1 number of equivalent conductors per radian linear current density, A/m in peripheral direction (current flows axially) resistance, inductance, H Fourier transform and inverse Subscripts I inner 2 outer D d-axis Q q. axis

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“…Finally, a comment on the influence of the environmental shield. (8). This improvement is unfortunately cancelled by the increase in Boo due to the magnetic shield.…”

Section: Are Shown Inmentioning

confidence: 99%

Section: Appendixmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The behaviour of screening systems in the superconducting a.c. generator

Miller

1977

Archiv f. Elektrotechnik

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“…The rotor screening system, consisting of the outer rotor and the radiation screen, presents an intriguing problem in the design of superconducting machines as it must carry the full short-circuit force whilst maximising natural damping of rotor-hunting oscillations and minimising flux-density variations at the superconductor. Such a design requirement can be met by using a double-rotor construction [3][4][5][6]. In this the outer rotor is designed to withstand 95% of the short-circuit forces, to screen armature negativesequence fluxes and reduce substantially the flux-density variations at 50 Hz seen by the radiation screen during a fault.…”

Section: List Of Symbolsmentioning

confidence: 99%

“…where k t is a magnetic outer rotor factor and is given by (5) k t can now be introduced into the power ouput equation to give (6) with k t being found iteratively by the method described in Section 3. Typical values of k { are 0.9 to 0.99, indicating a reduction in generator specific power output due to the flux shunting effect of the outer rotor.…”

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confidence: 99%

Superconducting AC generator with a magnetic steel outer rotor

Bumby¹

1981

IEE Proc. C Gener. Transm. Distrib. UK

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The specific power output per unit length of large superconducting AC generators is limited by the material properties, of the outer rotor. By manufacturing this component from a high strength magnetic steel, such as is used in. conventional turbogenerator rotors, the diameter of this component can be increased producing an increase in the specific power output. This paper demonstrates the feasibility of using a magnetic outer rotor and shows that advantages are to be gained in respect of generator systems performance and ease of manufacture as well as improved specific power output. List of symbolsA = electric loading, A/m A z = axial component of vector potential B o = flux density at axial centre of air-cored superconducting AC generator, T. B o = /JL 0 K O / 2 B r = radial component flux density, T H r -radial component magnetic, field, A/m HQ = tangential component magnetic field, A/m K o = superconducting field winding linear current density, A/m L'a = subtransient inductance, H L s = synchronous; inductance of generator with magnetic outer rotor, H L so = synchronous inductance of generator with nonmagnetic outer rotor, H P = power output, W R = winding resistance, O, T ph = number of turns in series/phase ki = magnetic outer rotor factor k w= winding factor k r = radial flux density environmental screen factor k e = trangential flux density environmental screen factor / = generator length, m n =• generator speed, rev/s r -radius of field point, m ri = inner radius outer rotor, m r 2 = outer radius outer rotor, m r D -mean radius outer rotor, m r 0 = mean radius superconducting field winding, m r s = mean radius armature windings, m r x = inner radius environmental screen, m t = winding thickness, m 6 = circumfrential position, rad Hi = incremental permeability H o = permeability of free space H/m H r = relative permeability p = resistivity, flm a o.2 = 0.2% (300K) proof stress of inner rotor N/mm 2 i// = internal power factor angle, rad

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Equivalent circuit modeling of a superconducting synchronous generator with double electromagnetic shields (Part II. Equivalent circuit model and estimation of its constants for design examples)

Muta

Magarikaji²

1980

Electrical Engineering Japan

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A design concept for large superconducting alternators

Cited by 21 publications

References 8 publications

The behaviour of screening systems in the superconducting a.c. generator

The behaviour of screening systems in the superconducting a.c. generator

Superconducting AC generator with a magnetic steel outer rotor

Equivalent circuit modeling of a superconducting synchronous generator with double electromagnetic shields (Part II. Equivalent circuit model and estimation of its constants for design examples)

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