MXPA00007028A - A method for constructing a superconducting multiphase cable comprising n phases - Google Patents

Abstract

By a method for constructing a superconducting multiphase cable comprising N phases, the phases are divided into n groups with N phases in each group, all the groups having a common screen. The individual groups may be geometrically formed with coaxial or flat phases. The individual phases in each group may further be divided into individual conductors such as tapes. The insulation between the individual conductors in the groups may be separately insulated from each other or have a common insulation. In a particularly appropriate embodiment, the number of groups is 1 and implemented with a flat or concentric geometry. In this way, a compact superconducting power cable is provided, which is relatively inexpensive in production and has few working operations while maintaining good electrical properties.

Description

A METHOD OF CONSTRUCTION OF A MULTI-PHASE SUPERCONDUCTOR ON CABLE, COMPRISING N PHASES Field of the Invention The invention relates to a method for constructing a superconducting multi-phase cable comprising N phases, wherein each phase in the cable is divided among a number of conductors and wherein the insulation means are distributed in the cable, the phases are divided into n groups, each group that has N different phases.

Background of the Invention Superconducting cables use the low resistance in superconducting materials achieved when the superconducting material is exposed to a temperature that is lower than its so-called critical temperature. This temperature may be, for example, 4-7 K (low temperature superconductor, LTS) or 30-10 K (high temperature superconductor, HTS). For use at room temperature, an artificial refrigerant and thermal insulation are usually required to thermally separate the conductor from the cable from its surroundings.

REF .: 121743 Superconductor cables can be produced from a superconducting band wound around a central cooling channel. A layer of electrically conductive material is then applied coaxially. A screen or coaxial screen which is either superconductive or conductive normally, can then be applied. A thermally insulating layer can be applied either between the inner superconducting layer and the electrical insulation or on the outer side of the electrical insulation. Accordingly, the electrical insulation is either exposed to a high temperature (room temperature) or a low temperature (cryogenic temperature). In addition, such a cable can have an external diameter typically in the range from 8 to 15 cm. The electrical AC loss that occurs in the superconductor can be reduced by winding a band or superconducting wire around a cooling channel, the winding is done with ascending angles in such a way that even a distribution of the current between the individual bands / wires be obtained. They can also be wound around several cooling channels, for example as described in U.S. Pat. No. 4,327,244. If the capacity to carry the current of the cables of this type is going to be increased, this can be obtained by increasing the amount of the superconducting material. However, this leads to an increased generation of reactive power, since the inductance / reactance of the cable becomes relatively high, which can cause undesirable phase changes in the voltage and electrical current transported, especially in the sections of the cable long but also in short sections of cable to which a low voltage is applied and a high current is conducted. Normally, this reactance / inductance can increase the diameter of the internal semiconductor in for example 30-50 cm. Even though the reactance / inductance is decreased by this, this reduction also has disadvantages such as for example larger cable dimensions, increased consumption of the materials, and finally increased heat transfer because of the increased area of the insulation thermal. Other methods are described in the literature, which allow the reduction of the reactance / inductance of a superconducting cable system. Normally, electrical insulation and electro-wire are included in the cable systems known for single-phase AC cables, where 3 cables with a one-phase conductor each are used to provide 3 phases.

From the patent EP 0 786 783 A1 a multi-phase superconducting cable is known, in which the individual phases are divided into a number of individual conductors. Each of the individual conductors is isolated from each other and equipped with a superconducting screen. Evidently, this leads to a rather expensive and bulky cable, since each individual conductor constitutes a "cable" with a conductor, a screen and two layers of insulation. DE 4340046 A1 discloses a superconducting cable, in which 3 phases are located coaxially in a manner related to each other and are surrounded by a common return circuit. The reduced consumption of material is made possible as well, since the conductors of three phases have a common screen. The diameter of the conductors of individual phases can be increased with the purpose of reducing the inductance without an increase in volume being required, which could be the case if 3 individual cables were used. However, the disadvantage is that a sufficiently reduced inductance will not be obtained, since the ratio between the reactance and the diameter is logarithmic. Similarly, from JP 1231217 a multi-phase superconducting cable is known, in which the individual phase conductors consist of a cooling channel, a superconducting phase conductor, an electrical isolation, in which each individual phase conductor is surrounded by a normally conductive screen. This reduces the consumption of the superconducting material. Since the normally conductive screen is resistive, according to this technique it is necessary to minimize the induced current in these resistive screens by arranging or distributing the individual phase conductors in a triangular configuration, in which each individual phase conductor has a different phase conductor. as a neighbor. The most important techniques of division of the phases described above have the advantage that the production of reactive power is reduced, compare the law of the parallel coupling of the reactances / inductances. The reduction of the electric current in each individual phase conductor also reduces the magnetic field on the surface of the conductor of the phase and the electrical AC loss in the superconducting material. Accordingly, the disadvantage of these known techniques is that the individual phase conductors consist of independent, complete cables, with a cooling channel, conductors of the cable, an electrical insulation and an electro-winding. In practice, it is impossible to produce a compact and economical cable if a large number of groups with a number of phases in each group is desired. It is now an object of the invention to facilitate the manufacture of a superconducting power cable, preferably for use at 1 kV-132 kV, the superconducting power cable is less bulky, has higher efficiency and lower manufacturing costs when compare with the output, also for a large number of groups. It is an additional purpose to reduce the reactance / inductance in a superconducting cable system, without the cable system being more bulky or more expensive than those known up to now. The object of the invention is satisfied by a number of N groups of phase conductors, which are assembled into groups and by one or more of the groups that are equipped with a common electro-burn. In this way, a cable can be manufactured in such a way that the electrical insulation can be produced essentially in a working step which is carried out before the various conductors of the phase are assembled in a cable either by the application on the conductors of the phase of the individual superconductors and / or by the production of an electrically insulating sheet. Accordingly, a production is obtained, which is more compact and has lower costs associated therewith, since the number of work operations during the production of the cable can be reduced, the individual phases do not have individual electro-ignitions. For a further minimization of manufacturing costs, it is preferred, as specified in claim 2, that the individual phases contain only the superconducting cable wire and an insulation system. For an additional simplification of the manufacturing process, the groups can, as specified in claim 3, be arranged or distributed in n coaxial groups, either with various different phase conduits in each coaxial layer or with each individual phase conductor in a separate coaxial layer. In this way, a simpler cooling system with a limited number of flow paths for the refrigerants could be provided. By arranging or distributing the groups in the N plane phases as specified in claim 4, the magnetic field generated by the current in the phases will be relatively long, so that the magnetic induction in the cable is reduced. In this arrangement or distribution, preferably, one or more electrically insulating sheet systems can be used as the electrical insulation, the sheet system (s) consisting of one or more layers of insulating materials and optionally electrically conductive materials. The use of the electrically conductive layers of the surface or sheet coatings implies that this coating can be removed optionally from the selected parts of the sheet or it can be selected not to apply this coating on the selected parts of the sheet. In addition, the appropriate embodiments of the invention are specified in the dependent claims. The invention will now be described in more detail with reference to the exemplary embodiments of the invention illustrated in the drawings, in which: Figure 1 shows schematically a first embodiment of the cable according to the invention, Figure 2 is a second embodiment of the cable according to the invention, Figure 3 is a first variant of the embodiment according to Figure 2, Figure 4 is a second variant of the embodiment according to Figure 2, Figure 5 is a third variant of the embodiment according to Figure 2, and Figure 6 is a third embodiment of the cable according to the invention.

Detailed description of the invention In Figure 1, 1 designates a superconducting cable in its entirety in a first embodiment of the invention. The cable in the example shown is a 3-phase cable, in which each phase is denoted by one of the letters a, b or c. The phases are divided into a number of individual conductors which are designated by a number 1-n. Therefore, the designation na designates a conductor no. n with phase a. As shown, the conductors are divided into a number of groups n, each of the groups has a number of conductors, which corresponds to the number of phases which is 3 in the example shown. Surrounding the individual conductors completely, a surrounding neutral conductor 4 is shown, which can constitute a common screen. According to the invention, this common screen can surround one or more groups of phases. The refrigerant can be applied to each individual phase conductor, to each individual group, to a number of the groups, or preferably to the complete cable with a pipe system. The refrigerant can flow in one or more directions in this pipe system.

This construction of the cable, especially in the preferred embodiment, provides an extremely compact construction with optimum electrical properties such as low impedance. A second embodiment of a superconducting power cable according to the invention is shown in Figure 2. When compared to the embodiment of Figure 1, a 3-phase, flat cable 5 is shown, in which each phase is designated again by 'a, b, c. In the example shown, the phases are divided into 2 groups 6 and 7 but naturally, there is nothing to prevent the number of groups being 1 or more. As shown, each phase in each group consists of a number of tapes arranged or distributed in rows. In the example shown, all the rows are separated by the same insulation 18. Alternatively, a wide band with a corresponding geometry can be implemented as shown in Figure 5, in which each phase in each group is separated by layers of insulation . Figure 3 shows a further variant, where each individual phase of each group is comprised of the same insulation as in Figure 3, denoted by 13 and 14. In this way, an electrical insulation is obtained, in which each individual surface of an insulating band only refers to a specific phase. The risk that the current flows between the phases is reduced in this way. If, as shown in Figure 4, reference number 18, the 2-sheet systems of Figure 3 are assembled to a continuous sheet, an additional extended leakage path is obtained without increased space requirements. Therefore, in the mentioned modes, the magnetic fields induced in the cable, which are generated during the conduction of the current, have to travel a greater distance, which in turn leads to a lower impedance of the cable. Figure 6 shows a variant of the embodiment according to Figure 5, Figure 6 shows a cable with a circular cross section, in which the individual phases 10-12 are arranged or distributed concentrically. As shown, each layer consists of a number of tapes arranged or distributed in a manner analogous to the embodiment of Figure 4, that is, there are n tapes in each layer. Accordingly, there are several groups of n phase conductors in each layer. Finally, the Figure shows a common channel 9 for the refrigerant. However, cooling can be provided in several ways in a pipe system. The aforementioned electro-sound which can surround one or more groups of phases can consist totally or partially of superconducting, metallic, and semiconductor materials, even in combination with non-conductive materials and compounds such as, for example, the impregnation of the paper with mineral carbon powder. One or more of these compounds can be impregnated with a porous or non-porous ceramic or polymeric material which may have a low or high thermal conductivity, so that the cooling can be carried out by means of the conduction of the solid and / or through a medium such as liquid or gaseous N2, He2 or Ne which penetrate the porous material and between one or more of the phases or groups of phases. It can be seen that this refrigerant or an alternative refrigerant can impregnate the electrical insulation to improve the electrical insulation properties. Even though the invention has been explained in relation to the specific embodiments, described together with Figures 1-3, there is, of course, nothing to prevent other embodiments being formed within the scope of the claims. The cross sections of the cables can take for example other forms; they may be, for example, oval, angular, and the like.

It is noted that in relation to this date the best method known by the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Having described the invention as above, property is claimed as contained in the following

Claims (13)

1. A method for constructing a superconducting multi-phase cable comprising N phases, wherein each phase in the cable is divided into a number of conductors, and where the isolation means are arranged or distributed in the cable, the phases are divided into n groups, each group having N different phases, characterized in that a number of N groups of conductors of the phase are assembled into groups and because one or more of the groups is / are provided with a common electro-sound.

2. A method according to claim 1, characterized in that the individual phases only contain the wire of the superconducting cable and an isolation system.

3. A method according to claims 1-2, characterized in that the groups are arranged or distributed in n coaxial groups, either with different conductors of the different phase in each coaxial layer or with each individual phase conductor in a separate coaxial layer.

4. A method according to claims 1-2, characterized in that the groups are arranged or distributed in N flat phases.

5. A method according to claim 4, characterized in that each of the phases is constructed by one or more individual conductors such as tapes.

6. A method according to claims 1-5, characterized in that the number of groups is 1.

7. A method according to claims 1-3, characterized in that the number of groups is 1 and that the N-phases are arranged concentrically with a concentric isolation between each of the N phases.

8. A method according to claims 1-7, characterized in that the phases in each group are isolated electrically and separately from each other.

9. A method according to claims 1-8, characterized in that the phases in each group are isolated from each other by a common insulator.

10. A method according to any of claims 1-9, characterized in that the number of groups n is large, preferably greater than 10 and more preferably greater than 100.

11. A method according to claims 1-10, characterized in that the electro-burn is maintained at a potential of 0 and consists totally or partially of a semiconductor material or of a combination of these materials and is placed close to the electrically insulating material.

12. A method according to claims 1-11, characterized in that the individual phases in each group have such permissiveness that they cooperate magnetically.

13. A method according to claims 1-12, characterized in that at least one of the phases is constituted by a neutral conductor. A METHOD OF CONSTRUCTION OF A MULTI-PHASE SUPERCONDUCTOR CABLE, COMPRISING N PHASES SUMMARY OF THE INVENTION The present invention relates to a method for the construction of a superconducting multi-phase cable comprising N phases, the phases are divided into n groups with N phases in each group, all groups have a common screen. Individual groups can be formed geometrically with coaxial or flat phases. The individual phases in each group can be further divided into individual conductors such as tapes. The insulation between the individual conductors in the groups can be isolated separately from each other or have a common insulation. In a particularly suitable embodiment, the number of the groups is 1 and implemented with a flat or concentric geometry. In this way, a compact superconducting power cable is provided, which is relatively inexpensive in its production and has few working operations, while maintaining good electrical properties.