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Transient Cooling of a Faultworthy Superconducting Electric Generator

  • J. A. Schwoerer
  • J. L. SmithJr.
Part of the Advances in Cryogenic Engineering book series (ACRE, volume 35 A)

Abstract

In order for superconducting generators to be of use in power stations, they must be made faultworthy, or able to withstand the effects of a short circuit on the power lines. The work described herein is part of an MIT-DOE program to design a 2000-MVA generator, the size of commercial interest, and to build and test a 10-MVA prototype. Designs of faultworthy superconducting generators to date have stationary, normally conducting armatures, rotating superconducting field windings, and several rotating electromagnetic shields between the field winding and the armature [1-3]. The MIT design has two electromagnetic shields and is unique in that these are structurally part of the rotor and operate in the steady state at temparatures in the range of 4 to 6 K. A system of cold shields, as opposed to having at least the outermost shield self-supporting and at room temperature, simplifies the structural problem and has other advantages, but it makes the cooling problem much more difficult [1]. For a representative 2000-MVA design, subjected to a severe fault used for design purposes, the time-averaged total losses in the shields are 4 MW during the first 0.1 s and thereafter drop by an order of magnitude and decay exponentially. The transient cooling scheme must prevent this heat input from increasing the temperature of the superconductor to the level where it will go normal.

Keywords

Heat Input Check Valve Isentropic Compression Electromagnetic Shield Transient Cool 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Notation

Notation

h

= specific enthalpy

r

= mass flow rate from reservoir to shield

υ

= mass flow rate in vent line

P

= pressure

Q̇

= total rate of heat generation in the shield

t

= time since start of transient

u

= specific internal energy

V

= shield void volume

ρ

= density

Subscripts

s

= shield state (assumed uniform)

r

= state at bottom of reservoir

CM

= state of control mass

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References

  1. 1.
    Cryogenic Engineering Laboratory and Electric Power Systems Engineering Laboratory, Massachusetts Institute of Technology, “Demonstration of an Advanced Superconducting Generator,” U. S. DOE Interim Report E(49–18)-2295, Task Order No. 11, IR1, Sec. I.B.I; IR 4, Sec. II.A.3; IR 7, Sec. I.D, Sec. IV.D; IR 8 Sec. IV.D.2.Google Scholar
  2. 2.
    J. H. Parker and R. A. Towne, “Superconducting Generator Design,” EPRI Final Report EL-557(1977).Google Scholar
  3. 3.
    M. J. Jefleries and P. A. Rios, “Superconducting Generator Design,” EPRI Final Report EL-663 (1978).Google Scholar
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    R. G. Scurlock and G. K. Thornton, Intern. J. Heat Mass Transfer 20:31 (1977).CrossRefGoogle Scholar
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    L. F. Shampine and M. K. Gordon, Computer Solution of Ordinary Differential Equations, W. H. Freeman, San Francisco (1975).Google Scholar
  6. 6.
    R. D. McCarty, NBS Tech. Note 631 (1972).Google Scholar
  7. 7.
    J. A. Schwoerer, M.S. thesis. Dept. of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts (1978).Google Scholar

Copyright information

© Springer Science+Business Media New York 1980

Authors and Affiliations

  • J. A. Schwoerer
    • 1
  • J. L. SmithJr.
    • 1
  1. 1.Massachusetts Institute of TechnologyCambridgeUSA

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