Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F36/00—Transformers with superconductive windings or with windings operating at cryogenic temperature
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
  • Y02E40/60—Superconducting electric elements or equipment; Power systems integrating superconducting elements or equipment

Definitions

• the present invention relates to a transformer with super ⁇ conducting windings and without an iron core.
• Designing a transformer with superconducting windings without an iron core entails special problems as regards insulation, magne ⁇ tization current, losses, etc.
• a coreless transformers with superconducting windings entails advantages which contribute to make such a transformer both less expensive and less heavy than a conventional transformer for the same power. Because of the costs associated with installations for achieving a superconducting state of the windings, however, transformers currently available primarily belong to the category of power transformers.
• the magnetic field in the main channel is limited to 1 T for a pair of windings in which each winding has a thickness of 0.4-0.7 m. Then, assuming that the copper area only constitutes about 20-25 % of the opening of the core window, the current density will only be 0.5-1 A/mm 2 in this window.
• HTSC high-temperature supercon ⁇ ductors
• Reference (D) presents still another method of calculation, based on the equivalent transformer circuit from reference (B) , for a coreless transformer with superconducting windings on the basis of given electrical data.
• the method shows that the size of such a transformer is smaller and its weight considerably smaller than for a conventionally wound transformer with an iron core with corresponding electrical data. The reduced size and weight become still more accen ⁇ tuated for a corresponding shunt reactor.
• the experimental transformer comprises five windings, of which the.primary winding, in this case the high-voltage winding, consists of two concentric inner and two concentric outer sub-windings, and where the intermediate fifth winding is the secondary winding of the transformer.
• the inductance which the supply source senses at no-load operation will be higher when these sub- windings are connected together so that the fields caused thereby are summed in the central cavity. This is due to the fact that the stored energy is proportional to the field strength squared, multiplied by the enclosed volume.
• the division into four sub-windings means that the field strength increases by a factor of four and the enclosed volume decreases by a factor of four. Thus, the no-load current will substantially decrease by a factor of two.
• both the reactive power at rated current and the short-circuit reactance of the transformer will also be four times higher than if the primary winding is not divided. Both of these quantities are, however, reduced by placing the secondary winding, as in reference (D) , between the sub-coils in the divided primary winding. This results in a field configuration at rated current which is clear from the unbroken line in Figure 1.
• Figure 1 shows the field distribution of a coreless trans ⁇ former with a primary winding divided into four parts, con ⁇ sisting of two inner and two outer layers, and with an intermediate secondary winding.
• Figure 2 shows the field distribution of a coreless trans ⁇ former with a primary winding divided into four parts and a secondary winding divided into four parts, wherein the sub- windings are interleaved.
• the present invention relates to a winding design which, in relation to the state of the art described above, permits an additio ⁇ nally reduced reactive power for coreless power transformers with superconducting windings. This can be done by allowing the secondary winding also to consist of a number of sub- windings, corresponding to the number of sub-windings with which the primary winding is designed, the sub-windings of the secondary windings being interleaved with the sub- windings of the primary winding.
• the interleaving means that the wind ⁇ ing package is composed of, counting from the outside, a secondary sub-winding, Sl, space for insulation and mechani ⁇ cal support, a primary sub-winding, Pl, space for insulation and mechanical support, a secondary sub-winding, S2, space for insulation and mechanical support, a primary sub- winding, P2, etc., depending on how many sub-windings the winding package consists of.
• the winding package may be composed of, counting from the out ⁇ side, a primary sub-winding, space for insulation and mecha ⁇ nical support, a secondary sub-winding, etc.
• the interconnection between the sub-windings shall be such that the fields caused thereby are summed in the inner central cavity.
• the scope of the invention allows for the windings to be divided into less than four and more than four sub-windings, respectively. If one of the windings is divided into "n" windings, the other winding may be divided into "n+1" wind ⁇ ings.

Landscapes

• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Coils Of Transformers For General Uses (AREA)
• Coils Or Transformers For Communication (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (1)

Family

ID=20401058

Family Applications (1)

Country Status (6)

Cited By (3)

Citations (1)

• 1996
  • 1996-01-18 SE SE9600173A patent/SE507576C2/sv not_active IP Right Cessation
• 1997
  • 1997-01-07 WO PCT/SE1997/000011 patent/WO1997026668A1/en active IP Right Grant
  • 1997-01-07 JP JP9525901A patent/JP2000503474A/ja not_active Ceased
  • 1997-01-07 DE DE69728301T patent/DE69728301T2/de not_active Expired - Lifetime
  • 1997-01-07 AT AT97901290T patent/ATE262728T1/de not_active IP Right Cessation
  • 1997-01-07 EP EP97901290A patent/EP1021811B1/en not_active Expired - Lifetime

Patent Citations (1)

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