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WO2000039815A1 - Stockage d'energie magnetique - Google Patents

Stockage d'energie magnetique Download PDF

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Publication number
WO2000039815A1
WO2000039815A1 PCT/EP1999/010508 EP9910508W WO0039815A1 WO 2000039815 A1 WO2000039815 A1 WO 2000039815A1 EP 9910508 W EP9910508 W EP 9910508W WO 0039815 A1 WO0039815 A1 WO 0039815A1
Authority
WO
WIPO (PCT)
Prior art keywords
coil
superconducting
smes
smes device
high voltage
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/EP1999/010508
Other languages
English (en)
Inventor
Udo Fromm
Christian Sasse
Pär Holmberg
Nicholas Warren
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ABB AB
Original Assignee
ABB AB
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from GBGB9828651.1A external-priority patent/GB9828651D0/en
Priority claimed from GBGB9912608.8A external-priority patent/GB9912608D0/en
Application filed by ABB AB filed Critical ABB AB
Priority to AU30447/00A priority Critical patent/AU3044700A/en
Publication of WO2000039815A1 publication Critical patent/WO2000039815A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F6/00—Superconducting magnets; Superconducting coils

Definitions

  • a SMES device is normally built as a coil.
  • the inductance should be as high as possible. Therefore, the superconductor is conventionally wound into a pancake, for example a 4 T background coil for SMES as described in "Design and construction of the 4 T background coil for the navy SMES cable test apparatus", IEEE Transactions on Applied Superconductivity, Vol 7, No 2 , June 1997.
  • the SMES devices are normally connected to voltages of up to about 500 V and currents of around 1000 A.
  • the resistance can only be reduced by selecting a material for the layer having a higher resistivity.
  • the resistivity of the semiconducting outer layer is too great the voltage potential between adjacent spaced apart points at a controlled, e.g. earth, potential will become sufficiently high as to risk the occurrence of corona discharge with consequent erosion of the insulating and semiconducting layers.
  • the semiconducting (outermost) outer layer is therefore a compromise between a conductor having low resistance and high induced voltage losses but which is easily connected to a controlled electric potential, typically earth or ground potential, and an insulator which has high resistance with low induced voltage losses but which needs to be connected to the controlled electric potential along its length.
  • the coil has many turns in order to achieve high inductance.
  • the superconducting means itself is coated with an electrically insulating material to withstand potential differences of several volts, typically between 0.1 to 100 volts and a maximum of 1000 volts. In normal operation the turn to turn voltage is typically around one volt caused by the induced flux in the air core of the coil and applying an external AC source to the superconducting means.
  • the coil may also consist of several conductor layers electrically insulated against each other, either connected in parallel or in series to each other.
  • the superconducting means may comprise low temperature superconductors, but most preferably comprises high- temperature superconducting (HTS) materials, for example electrically insulated HTS wires or tape helically wound on an inner tube.
  • HTS tape conveniently comprises silver-sheathed BSCCO-2212 or BSCCO-2223 (where the numerals indicate the number of atoms of each element in the [Bi, Pb] 2 Sr 2 Ca 2 Cu 3 O x molecule) and hereinafter such HTS tapes will be referred to as "BSCCO tape(s)".
  • the filling factor of HTS in the matrix needs to be high so that the engineering current density j ⁇ >- 10 4 Acm "2 . j c should not drastically decrease with applied field within the Tesla range.
  • the helically wound HTS tape is cooled to below the critical temperature T c of the HTS by a cooling fluid, preferably liquid nitrogen, passing through the inner support tube.
  • the SMES device may form part of a modular system comprising several SMES devices connected together in parallel to increase the total storage.
  • the invention as herein described can also be used with conventional low-temperature superconducting materials and with low-temperature coolants such as liquid helium.
  • FIG. 1 is a circuit diagram of an SMES device according to the present invention.
  • Figures 2A and 2B are an enlarged, schematic, sectional view, and a schematic perspective view, respectively, of one embodiment of a high-temperature superconducting cable which incorporates the coil of the SMES device of Figure 1;
  • FIG 3 an enlarged, schematic, sectional view of another embodiment of a high-temperature superconducting cable which incorporates the coil of the SMES device of Figure 1;
  • Figure 8 is a schematic view of two converter stations with voltage source converters and combined with a high voltage bipolar dc link.
  • varnish insulation removed therefrom at its opposite ends and preferably also at spaced apart positions along its length so that the inner layer 7 is in electrical contact with the HTS material at opposite ends of the coil and also, preferably, at spaced apart positions along is length.
  • the inner layer of semiconducting material makes electrical contact with the coil at every n turns of the coil ⁇ O.ln turns, where n is typically from 100 to 10,000, typically about 1000.
  • the layers 6-8 preferably comprise thermoplastics materials in close mechanical contact or preferably solidly connected to each other at their interfaces. Conveniently these thermoplastics materials have similar coefficients of thermal expansion and are resilient or elastic at least at room temperature.
  • the solid insulating layer 6 may comprise cross -linked polyethylene (XLPE) .
  • the solid insulating layer may comprise other cross-linked materials, low density polyethylene (LDPE) , high density polyethylene (HDPE) , polypropylene (PP) , polymethylpentene (PMP) , ethylene (ethyl) acrylate copolymer or rubber insulation, such as ethylene propylene rubber (EPR) , ethylene-propylene-diene monomer (EPDM) or silicone rubber.
  • the inner and outer layers 7 and 8 of semiconducting material may comprise, for example, a base polymer of the same material as the solid insulating layer 6 and highly electrically conductive particles, e.g.
  • volume resistivity of these semiconductive layers may be adjusted as required by varying the type and proportion of carbon black or other conductive particles added to the base polymer. The following gives an example of the way in which resistivity can be varied using different types and quantities of carbon black.
  • the outer semiconducting layer 8 is connected at spaced apart regions along its length to a controlled potential, e.g. via electrically conductive strips.
  • this controlled potential will be earth or ground potential, the specific spacing apart of adjacent earthing points, i.e. the spacing apart of the earthing strips, being dependent on the resistivity of the layer 8, although it is possible to provide a continuous strip, e.g. an earthing strip or a wire, along the length of the outer layer 8.
  • the semiconducting layer 8 acts as a static shield and as an earthed outer layer which ensures that the electric field of the coil 1 is retained within the solid insulating layer 6 between the semiconducting layers 7 and 8. Losses caused by induced voltages in the layer 8 are reduced by increasing the resistance of the layer 8.
  • the layer 8 since the layer 8 must be at least of a certain minimum thickness, e.g. no less than 0.8 mm, the resistance can only be increased by selecting the material of the layer to have a relatively high resistivity. The resistivity cannot be increased too much, however, else the voltage of the layer 8 mid-way between two adjacent earthing points will be too high with the associated risk of partial discharges occurring.
  • the superconducting coil 1 may be cooled by a cooling fluid, such as liquid nitrogen, to the required superconducting temperatures.
  • a cooling fluid such as liquid nitrogen
  • the liquid nitrogen may be passed along a channel (not shown), e.g. an annular channel formed between the support tube 5 and an inner, concentrically arranged tube (not shown) spaced from the support tube 5. It is also possible to enclose the coil 1 and switch 3 in a cryostat 100 (shown schematically in dashed lines in Figure 1) .
  • Helically wound electrically insulated elongate HTS material for example BSCCO tape or the like, is wound on the support 122 to form a second coil 123 around the tubular support 122 having its individual turns electrically insulated from each other.
  • the HTS material forming the second coil 123 has its electrical insulation, e.g. varnish insulation, removed therefrom at its opposite ends and preferably also at spaced intervals along its length so that the surrounding layer 125a is able to make electrical contact with the coil 123 along its length.
  • a further band 125 of insulation is positioned around the second coil 123.
  • the band 125 comprises inner and outer layers 125a and 125b of semiconducting material and an intermediate layer 125c of insulating material.
  • the gaps 128 and 126 may be void spaces or may incorporate foamed, highly compressible material to absorb any relative movement between the superconducting coils and surrounding electrical insulation.
  • the foamed material if provided, may be semiconducting to ensure electrical contact between the coil 102 and layer 120a and the coil 123 and layer 125a. Additionally, or alternatively, metal wires may be provided for ensuring the necessary electrical contact.
  • a cryostat 115 arranged outside the semiconducting layer 125b, comprises two spaced apart flexible corrugated metal tubes 116 and 117. The space between the tubes 116 and 117 is maintained under vacuum and contains thermal superinsulation 118. Instead of the cryostat 115, the induction device may be contained within a thermally insulated, cryogenically cooled container shown schematically at 150.
  • FIG 4 shows an alternative cable construction in which the single coil 1 enclosed within a cryostat 9 (the same reference numerals have been used in Figures 2 and 4 where possible to identify similar parts) to cool the coil to superconducting temperatures.
  • the cryostat 9 comprises two spaced apart flexible corrugated metal tubes 9a and 9b. The space between the tubes 9a and 9b is maintained under vacuum and contains thermal superinsulation 9c. Liquid nitrogen, or other cooling fluid, is passed along the tubular support 5 to cool the surrounding superconducting coil 1 to below its critical superconducting temperature T c . The coil 1 at spaced intervals along its length will make electrical contact with the layer 7.
  • an insulation system is obtained by combining film and fibrous insulating material, either as a laminate or as co-lapped.
  • An example of this insulation system is the commercially available so-called paper polypropylene laminate, PPLP, but several other combinations of film and fibrous parts are possible. In these systems various impregnations such as mineral oil or liquid nitrogen can be used.
  • Figure 6 shows a high voltage system comprising two high voltage ac networks, Nl and N2 , T1Y and T2Y are converter transformers in Y/Y coupling and TID and T2D are converter transformers in Y/D coupling.
  • SCR11, SCR12 , SCR21 and SCR22 are series-connected 6-pulse line-commutated bridge-connected converters.
  • the converters SCR11 and SCR12 are linked with the converters SCR21 and SCR22 via a dc link DCL which comprises an energy storage device in the form of a superconducting magnetic storage device SMES.
  • the voltage over the converters SCR11 and SCR12 is Ul and the voltage over converters SCR21 and SCR22 is U2.
  • ⁇ l and U2 are each controlled in a conventional manner by control equipment (not shown) connected with its respective converter.
  • the current I d runs through the dc link DCL and the device SMES .
  • Figure 7 shows the same basic high voltage system as Figure 6.
  • the superconducting magnetic energy storage device SMES is used as a storage device for the ac network Nl and is charged via the converters SCR11 and SCR12, with switch SI closed and switch S2 open.
  • the current through the coil can be measured and charging continues until a nominal value is reached.
  • SI opens and S2 closes.
  • SI closes and S2 is opened.
  • the superconducting magnetic energy storage device SMES is part of a high voltage dc transmission system with a dc link.
  • a pole control device, PCM is needed when providing the network N2 with power.
  • the invention has been described with specific reference to an SMES device having a coil for connection in series with a dc voltage source, the invention is also intended to embrace connection of the coil to an ac voltage source.
  • high voltage used in this specification is intended to mean up to 800 kV or even higher.
  • An SMES device may be connected to such high voltage networks and at high powers of up to 1000 MVA.
  • partial discharges, or PD constitute a serious problem for known insulation systems. If cavities or pores are present in the insulation, internal corona discharges may arise whereby the insulating material is gradually degraded eventually leading to breakdown of the insulation.
  • the electric load on the electrical insulation of the superconducting means of an SMES device according to the present invention is reduced by ensuring that the inner portion of the electrical insulation is at substantially the same electric potential as the superconducting coil at spaced apart locations along its length and that the outer portion of the electrical insulation is at a controlled potential.
  • the electric field is distributed substantially uniformly over the thickness of the electrically insulating portion of the insulation between the inner and outer potions.
  • a particularly advantageous SMES device is provided if the cable itself is wound as a solenoid or in a toroidal shape.
  • the toroidal shape is particularly advantageous since there is less leakage field outside the toroid.
  • the magnetic energy of the SMES device is stored both in the coil of the cable and in the solenoid or toroid providing better energy storage utilisation.
  • the current in the superconducting means can be divided into two components, one component flowing in the azimuthal direction with a constant radius and the other component flowing axially along the axis of the longitudinal axis of the cable. With such a design, the forces arising from azimuthal current component of the superconducting means wound as a helix results in outward radial forces.
  • the solenoid or "toroidal" shape need not have a circular cross-section but may, for example, be oval- shaped or D-shaped. In the case of a torus having a "D- shaped" cross-section, the "straight" part of the "D” would form an inner cylindrical wall of the "torus". It is also, of course, not essential for the torus to be perfectly annular or circular in shape.
  • An additional advantage of the present invention is that, since the SMES device operates at high voltage, the current can be reduced for a given power density. Thus for a conventional SMES device operating at 20 kv, a similarly powered SMES device according to the invention can operate at about 150 kV resulting in a reduction of the current of about 7.5 times. Since the magnetic force in the cable is proportional to current x magnetic flux density (B) , the magnetic force is effectively reduced about 7.5 times. Furthermore, the amount of semiconductor saved will, in this example, amount to approximately 7.5 times. Similarly, the cooling losses will be essentially reduced. All these factors improve the economic attractiveness of the SMES device.
  • the present invention is not limited to high temperature superconductivity. Due to the high magnetic field in magnetic energy storage, low temperature superconductors are still attractive, even though they require cryostats operating between 1-15 K, depending on the type of low temperature superconductor utilised.
  • Well known examples are based on Niobium, such as NbTi, Nb 3 Sn and Nb 3 Al. Other examples are V 3 Ga and Nb 3 Ge.
  • the most common superconductor used is NbTi which can be utilised in magnetic field densities up to approximately 9 T at 4.2 K (or 11 T at 1.8 K) . For higher field densities, NbTi cannot be used and is replaced by Nb 3 Sn.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Superconductors And Manufacturing Methods Therefor (AREA)

Abstract

L'invention se rapporte à un dispositif supraconducteur de stockage d'énergie magnétique (SMES) comportant au moins une bobine (1) conçue pour être reliée en série à une source de tension et fabriquée à partir d'un câble supraconducteur électriquement isolé (4). Le câble possède un organe supraconducteur interne enroulé en une ou plusieurs bobines et entourant l'isolation électrique externe. L'invention se rapporte également à un système haute tension comportant un dispositif SMES, dans lequel ledit dispositif SMES possède un organe de conduction supraconducteur enroulé sous forme d'une bobine et qui est isolé de la haute tension par un système d'isolation électrique disposé de manière concentrique autour de l'organe conducteur.
PCT/EP1999/010508 1998-12-23 1999-12-23 Stockage d'energie magnetique Ceased WO2000039815A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU30447/00A AU3044700A (en) 1998-12-23 1999-12-23 Magnetic energy storage

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
GB9828651.1 1998-12-23
GBGB9828651.1A GB9828651D0 (en) 1998-12-23 1998-12-23 Magnetic energy storage
GB9912608.8 1999-05-28
GBGB9912608.8A GB9912608D0 (en) 1999-05-28 1999-05-28 Magnetic energy storage

Publications (1)

Publication Number Publication Date
WO2000039815A1 true WO2000039815A1 (fr) 2000-07-06

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP1999/010508 Ceased WO2000039815A1 (fr) 1998-12-23 1999-12-23 Stockage d'energie magnetique

Country Status (2)

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AU (1) AU3044700A (fr)
WO (1) WO2000039815A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20040038576A (ko) * 2002-10-30 2004-05-08 석병관 콘덴서 기술을 적용한 에너지 저장 및 초전도 케이블
CN103833263A (zh) * 2012-11-23 2014-06-04 广西苏源投资股份有限公司 一种石头纸及其制备方法
WO2015195316A3 (fr) * 2014-06-04 2016-02-25 Novum Industria Llc Smes doubles découplés par induction dans un cryostat unique

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4431960A (en) * 1981-11-06 1984-02-14 Fdx Patents Holding Company, N.V. Current amplifying apparatus
GB2140195A (en) * 1982-12-03 1984-11-21 Electric Power Res Inst Cryogenic cable and method of making same

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4431960A (en) * 1981-11-06 1984-02-14 Fdx Patents Holding Company, N.V. Current amplifying apparatus
GB2140195A (en) * 1982-12-03 1984-11-21 Electric Power Res Inst Cryogenic cable and method of making same

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20040038576A (ko) * 2002-10-30 2004-05-08 석병관 콘덴서 기술을 적용한 에너지 저장 및 초전도 케이블
CN103833263A (zh) * 2012-11-23 2014-06-04 广西苏源投资股份有限公司 一种石头纸及其制备方法
WO2015195316A3 (fr) * 2014-06-04 2016-02-25 Novum Industria Llc Smes doubles découplés par induction dans un cryostat unique
US9721709B2 (en) 2014-06-04 2017-08-01 Novum Industria Llc Inductively decoupled dual SMES in a single cryostat

Also Published As

Publication number Publication date
AU3044700A (en) 2000-07-31

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