MXPA00005192A - Switch gear station - Google Patents

Abstract

A switch gear station comprises at least one switch gear (46) and at least one rotating electric machine (44) for high voltage. The machine comprises at least one winding including at least one electric conductor. The conductor has an insulation system comprising an insulation formed by a solid insulation material and, inwardly of the insulation, an inner layer having an electric conductivity which is lower than the conductivity of the electric conductor but sufficient to cause the inner layer to operate for equalisation as concerns potential and, accordingly, equalisation as concerns the electric field exteriorly of the inner layer. This design of the conductor enables direct connection of the winding of the rotating electric machine to a voltage power network.

Description

SWITCHING MECHANISM STATION FIELD OF THE INVENTION AND PREVIOUS TECHNIQUE This invention relates to a switching mechanism station comprising at least one switching mechanism and at least one rotating electrical machine comprising at least one winding that includes at least one electrical conductor . Such electrical machines comprise synchronized machines that are mainly used as generators for connection to distribution and transmission networks, commonly referred to below as energy networks. The synchronized machines are also used as motors and for phase compensation and voltage control in that case as mechanically dead time machines. The technical field also includes dual feed machines, asynchronous conversion cascades, external pole machines, synchronous flow machines and asynchronous machines. The coil may in some embodiments be wind-wound by air but as the rule of the magnetic circuit comprises a laminated, normal or oriented, sheet or other magnetic core material, for example amorphous or powder-based, or any other action for the purpose of allow an alternative flow. The circuit sometimes includes some kind of cooling systems, etc. The winding can be arranged in the stator or rotor of the machine, or in both. In order to be able to explain and describe the invention, the prior art will be discussed hereafter. Said rotating electric machine will be described by way of example on the basis of a synchronous machine. The first part of the description substantially refers to the magnetic circuit of said machine and how it is composed according to the classical technique. Since the magnetic circuit referred to in most cases is arranged in the stator, the magnetic circuit will normally be described as a stator with a laminated core, whose winding will be indicated as a stator winding, and the slots in The laminated core for the winding will be indicated as stator slots or simply slots.

Most synchronous machines have a field winding in the rotor, where direct current flow is generated, and an alternating current winding in the stator. Synchronous machines are normally of a three phase design. Sometimes, synchronous machines are designed with salient poles. The latter have an alternating current winding in the rotor. The stator body for large synchronous machines is usually made of a steel sheet with a welded construction. The laminated core is usually made of a varnished electric sheet of 0.35 or 0.5 mm. For larger machines, the blade is stamped into segments that are attached to the stator body by means of wedge-type / pigeon-shell inserts. The laminated core is retained by pressure pins and pressure plates. For cooling the windings of the synchronous machine, three different cooling systems are arranged. In the case of air cooling, both the winding of the stator and the winding of the rotor are cooled by cooling air flowing therethrough. Cooling air channels are found in both the stator laminates and the rotor. For radial ventilation and cooling by means of air, the core of iron sheets, at least in large and medium size machines, is divided into piles or api lamient, with radial and axial ventilation ducts that are arranged in the core. The cooling air may consist of ambient air but in the case of high energy or power a closed cooling arrangement with heat exchangers is used substantially. Hydrogen cooling is used in turbogenerators and large synchronous compensators The cooling method works in the same way as in air cooling with heat exchangers, but instead of air as a cooler, a hydrogen gas is used. Hydrogen gas has a cooling capacity better than that of air, but has the difficulty of losses in the seal and in the monitoring of losses. For turbogenerators in higher power ranges it is known to apply water cooling both in the winding of the stator and in the winding of the rotor. The cooling channels are in the form of tubes that are arranged inside the conductors in the stator winding. A problem that occurs in large machines is that cooling tends to become non-uniform and, therefore, temperature differences arise through the machine. The winding of the stator is arranged in grooves that occur in the core of iron sheets, the grooves typically having a cross section such as a rectangular or trapezoidal section. Each rolling phase comprises a number of groups of coils connected in series and each group of coils comprises a number of coils connected in series. The different parts of the coil are designed as coil sides for that part that is disposed in the stator and as a coil end for that part that is disposed outside the stator. A coil comprises one or more conductors arranged together with one another in height and / or width. A thin insulation is arranged between each conductor, for example made of epoxy or glass fiber.

The coil is insulated against the slot by means of a coil insulation, that is, an insulation whose purpose is to withstand the high voltage of the machine to ground. As an insulation material, various plastic, varnish and glass fiber materials can be used. Usually, a tape called mica is used, which is a mixture of mica and hard plastic, specially produced to provide resistance to partial discharges, which can quickly break the insulation. The insulation is applied to the coil by winding the mica tape around the coil in several layers. The insulation is impregnated and then the coil side is painted with a carbon based paint to improve contact with the surrounding stator that is connected to the ground potential. The conductive area of the windings is determined by the intensity of the current in question and by the cooling method used. The conductor and coil are usually formed with a rectangular shape to maximize the amount of conductive material in the slot. A typical coil is formed by the so-called Roebel bars, where some of the bars can be hollow for the passage of a cooler. A Roebel bar comprises a plurality of rectangular copper conductors, connected in parallel, which are transposed along 360 degrees in the groove. Ringland bars with transpositions of 540 yds and other transpositions can also be used. The transposition is made to avoid the occurrence of circulatory currents that are generated in a cross section of the conductive material, as seen from the magnetic field. For mechanical and electrical reasons, a machine can not be made in any size. The energy or power of the machine is determined substantially by three factors: The conductive area of the windings. At normal operating temperature, copper, for example, has a maximum value of 3 to 3.5 A / mm2. The maximum flux density (magnetic flux) in the stator and rotor material. The maximum resistance of electric field in the insulating material, the so-called dielectric resistance. Polyphase alternating current windings are designed either as a single layer or as windings of two cases. In the case of single-layer windings, only one side of the coil is available per slot, and in the case of the coils of two cases, two coil sides per slot are provided. The windings of two cases are usually designed as diamond windings, where the windings of a layer that are relevant in this connection can be designed as a diamond winding or as a concentric winding. In the case of a diamond winding, only one winding section (or possibly two winding sections) is present, so that the flat windings are designed as concentric windings, that is, with a very variable winding width. The coil width means the distance according to a circular measurement between two coil sides that belong to the same coil, either in relation to the relevant pole pitch or in the number of intermediate slot passages. Usually, different winding variants are used, for example with step in fraction, to give the winding the desired properties. The type of winding describes substantially how the coils are connected in the slots, that is, the coil sides, together with the outside of the stator, that is, with the coil ends. Outside the stacked sheets of the stator, the coil is not provided with a semiconductor layer painted with potential ground. The coil end is usually provided with a field control E in the form of the so-called corona protection by varnish whose purpose is to convert a radial field into an axial field, which means that the insulation at the coil ends occurs at a potential high with respect to earth. This sometimes causes a crown in the bobbin end region which can be destructive. The so-called field control points on the coil ends represent problems in a rotating electric machine. Usually, all large machines are designed with a winding of two cases and with equally large coils. Each coil is arranged with one side in one of the layers and the other side in the other layer. This means that all the coils are criss-crossed at the coil end. If more than two coils are used, this cross-linking makes the work of the winding difficult and the end of the coil deteriorates.

It is generally known that the connection of a synchronous generator or machine to a power grid must be done through a transformer called the connection elevator? / Y, since the voltage of the power grid is normally at a higher voltage than the Rotary machine voltage. Together with the synchronous machine, this transformer thus constitutes the integrated parts of a plant. The transformer constitutes an extra cost and is also a disadvantage in the sense that the overall efficiency of the system is reduced. If it were possible to manufacture machines for considerably high voltages, the use of the multiplier transformer could be omitted. During the last decades, the requirements for rotating electric machines have increased for higher voltages in relation to what previously had been possible to design. The maximum level of voltage that, according to the state of the art, it has been possible to achieve for synchronous machines with a good performance in the production of the winding is around 25 to 30 kV.

Some attempts to solve this problem have been described in terms of the design of synchronous machines, particularly in an article entitled "Water and il cooled Turbogenerator TVM-300" (Turbogenerator TV -300 cooled by oil and water), in the Publication J. Elekt Rotechnika, No. 1, 1970, p. 6-8, in U.S. Patent No. 4,429,244 relating to a "generator stator" and in Russian Patent Document CCCP 955369. The synchronous water and oil cooled machine described in Publication J. E 1 ekt rotechnika is designed for voltages up to 20 kV. The article describes a new insulation arrangement consisting of an oil and paper insulation, which makes it possible to immerse the stator completely in oil. The oil is then used as a cooler while, at the same time, it is used as insulation. To prevent the oil in the stator from escaping to the rotor, a dielectric oil separation ring is provided on the inner surface of the core. The winding of the stator is made from conductors with a hollow oval shape provided with oil and paper insulation. The sides of the coil with this insulation are secured to the grooves made with a rectangular cross section by means of shims. As a cooling oil, the oil is used both in the hollow conductors and in the holes in the walls of the stator. Such cooling arrangements, however, represent a major problem with respect to the connections of both oil and electricity at the ends of the coil. The thick insulation also represents an increased radius of curvature of the conductors, which in turn results in an increased size of the total winding. The aforementioned North American Patent refers to a stator part of a synchronous machine comprising a magnetic core of laminated sheets with trapezoidal grooves for winding the stator. The grooves are tapered because the insulation of the stator winding is less towards the inside of the rotor where said winding part is located closer to the neutral point. In addition, the stator part comprises a dielectric oil separation cylinder disposed closer to the inner surface of the core.

This part can increase the magnetization requirement with respect to a machine without this ring. The winding of the stator is made of cables immersed in oil with the same diameter for each layer of coil. The layers are separated from one another by spacers in the slots and are secured by wedges. What is special for this winding is that it comprises two winding media connected in series. One of the two half-windings is arranged centrally inside an insulation sleeve. The stator winding conductors are cooled by surrounding oil. The disadvantages in relation to that large amount of oil in the disposal are the risk of loss and the considerable amount of cleaning work that you might need in a fault situation. Those parts of the insulation sleeve that are located outside the grooves have a cylindrical part and a conical termination reinforced with current carrying layers, whose function is to control the resistance of electric field in the region where the cable enters the extreme winding. The Russian Document CCCP 955369 is clear, in another attempt to raise the voltage of the synchronous machine, that the oil-cooled stator winding comprises a conventional high-voltage cable with the same dimension for all the layers. The cable is arranged in the stator grooves formed as circular openings arranged in a radial manner, corresponding to the cross-sectional area of the cable and the space necessary for fixing and for a cooler. The different radially arranged layers of the winding are surrounded by, and fixed in, insulation tubes. Isolation spacers fix the tubes in the stator slot. Because an oil cooler is used, it is also necessary on this machine to have an internal dielectric ring to seal the coolant oil against an internal air gap. The design also shows a very narrow radial narrowing between the different stator slots, which means a large loss of flux in the groove that significantly influences the magnetization requirement of the machine. A report from the Electrical Energy Research Institute, EPRI, EL-3391, of 1984, describes machine concepts to achieve higher voltages in a rotary electric machine for the purpose of connecting a machine to a power grid without an intermediate transformer. According to the research, this solution would provide good efficiency gains and great economic advantages. The main reason that was considered possible in 1984 to start the development of generators for direct connection to power grids was that at that time a superconducting rotor had been produced. The large magnetization capacity of the superconducting field makes it possible to use an air gap winding with a thickness sufficient to withstand electrical stresses. Combining the highly promising concept, according to the project, of designing a magnetic circuit with a winding, so-called monolithic cylinder armature, a concept where the winding comprises two cylinders of electrically enclosed conductors in three cylindrical enclosures or shells and the General structure is fixed to an iron core without teeth, it was judged that a rotary electric machine for high voltage could be directly connected to a power grid. The solution indicated that the main insulation had to be made thick enough to withstand the potentials of network to network and of network to ground. Obviously the disadvantages with this proposed solution are that, in addition to requiring a superconducting rotor, it requires a very thick insulation that increases the size of the machine. The coil ends must be insulated and cooled with oil or freon gases to control the large electric fields at the ends. The total machine must be hermetically enclosed to prevent the dielectric liquid from absorbing moisture from the atmosphere. As it will emerge from the above description, the switch mechanisms station of today are likely to be improved. This is due to the mode of the same generator and the fact that the multi-liter transformers are required according to the prior art. It is pointed out that the term switching mechanism station related herein to a station, which is intended to collect and / or distribute electrical power and comprises equipment required for such activity, including a. or. equipment to commute and supervise.

BRIEF DESCRIPTION OF THE INVENTION The object of the present invention is mainly to provide a switching mechanism station, in which at least some of the disadvantages discussed in the foregoing and which deteriorate the prior art have been eliminated. The main object is obtained by means of a station of the class defined in the appended claims, and then particularly in claim 1. In a broad sense, it has been established that the design according to the present invention reduces, since it creates a possibility to substantially join the electric field that occurs due to the electrical conductor inside the insulation system, the loss occurs such that the machine, according to this, can operate with greater efficiency. The reduction of losses results, in turn, in a lower temperature in the device which reduces the need for cooling and allows the cooling devices to be designed in a simpler way than they would be without the present invention.

The conductor / insulation system according to the present invention can be carried out by means of a flexible cable, which means a substantial advantage with respect to the production and assembly in comparison with the prefabricated rigid windings that have been conventionally used. until now. The insulation system used according to the invention results in the absence of liquid and gaseous insulation materials. The rotary electric machine of the invention also makes it possible to operate the machine with a high voltage such that the aforementioned connected multiplier transformer can be omitted. That is, the machine can be operated with a voltage considerably higher than the machines according to the state of the art, which are capable of carrying out a direct connection with the power grids. This means considerably lower investment costs for systems with a rotating electric machine and the total efficiency of the arrangement can be increased. The invention eliminates the need for particular field control measures in certain areas of the winding, such field control measures being necessary according to the prior art. A further advantage is that the invention makes it simpler to obtain submagne t i z ac ion and supermagne t i z ac ion for the purpose of reducing reactive effects as a result that the voltage and current are out of phase one with respect to the other. In this way, the switching mechanism station as a whole becomes more efficient through reduced loss. In addition, the station as a whole is simplified so that this does not only become cheaper but also consumes less space. The design of the winding so that it comprises, along at least part of its length, an insulation formed by a solid insulating material, inside this insulation an inner layer and outwardly of the insulation an outer layer, these being Layers made of a semiconductor material, makes it possible to enclose the electric field in the entire device inside the coil. The term "solid insulating material" used herein means that the winding lacks liquid or gaseous insulation, for example in the form of an oil. Instead, the insulation is formed by a polymeric material. Also the inner and outer layers are formed by a polymeric material, and can also be a semiconductor. The inner layer and the solid insulation are rigidly connected to each other along substantially the total interface. Also the outer layer and the solid insulation are rigidly connected to each other along substantially the entire interface which is formed between them. The inner layer operates by introducing - an equalization with respect to the potential and, accordingly, an equalization with respect to the electric field externally to the inner layer, as a consequence of the semiconductor properties of it. The outer layer is also intended to be made of a semiconductor material and has at least one electrical conductivity that is greater than that of the insulation so as to cause the outer layer, by grounding or other relatively low potential, to function producing an equalization with respect to the potential and substantially enclosing the resulting electric field due to said electrical conduit internally to said external layer On the other hand, the external layer should have a resistivity that is sufficient to minimize the electrical losses in said external layer. The rigid interconnection between the insulating material and the inner and outer semiconductor layers should be uniform throughout the entire interface so that cavities, pores or the like are not produced With the high voltage levels contemplated according to the invention, electric and thermal charges that may appear will impose extreme demands on the mat insulation waste. It is known that the so-called partial discharges, PD, generally constitute a serious problem for the insulation material in high voltage installations. If the cavities, pores or the like appear in an insulating layer, crown-type internal discharges with high electrical voltages can occur, so that the insulating material is gradually degraded and the result could be an electrical break through the insulation. This can lead to a serious breakdown of the electromagnetic device. In this way, the insulation must be homogeneous.

The inside layer of the insulation should have an electrical conductivity that is lower than that of the electrical conductor but sufficient for the inner layer to work producing an equalization with respect to the potential and, accordingly, an equalization with respect to the electric field externally to the inner layer. This in combination with the rigid interconnection of the inner layer and the electrical insulation along substantially all the interface, that is, with the absence of cavities, etc., means a subsonially uniform electric field on the outside of the inner layer and a minimum risk of partial discharges. It is preferred that the inner layer and the solid electrical insulation be formed of materials having thermal coefficients of substantially equal expansion. This is also preferred in relation to the thermal layer and solid insulation. This means that the inner and outer layers and the solid electrical insulation will form an isolation arrangement that, in the face of temperature changes, expands and contracts uniformly as a monolithic part without those changes in temperature causing any destruction or disintegration in the interfaces. In this way, the closeness or intimate contact in the contact surface between the internal and external layers and the solid insulation is ensured and conditions are created to maintain this intimate contact during prolonged periods of operation. In addition, it is pointed out that it is essential that the materials in the inner and outer layer and in the solid insulation have a high elasticity so that the materials are able to withstand the tension that occurs when the cable is bent and when the cable during the operation is undergoes thermal stress. Efficient adhesion between the solid insulation and the inner and outer layers and high elasticity of these layers and solid insulation respectively is particularly important in the case that the materials in the layers and the solid insulation should not have substantially equal coefficients or Thermal expansion. Furthermore, it is preferable that the materials in the inner and outer layers and in the solid insulation have substantially equal elasticity. (Modules E), which will subtract the occurrence of shear stresses in the boundary area between the capable and the solid insulation. It is preferable that the materials in the inner and outer layer and in the solid insulation have modules E which is less than 500 MPA, preferably less than 200 MPA. To be able to form resistance by means of the cable, it is essential that the flexibility thereof is high. It is preferable that the cable must be capable of being clamped to be bent without negative influence on the function, with a bending radius that is 20 times the cable diameter or less, suitably 15 times the diameter of the cable or less. It is preferable that the cable must be capable of being bent in a bend radius in the amount of 4 to 5 times the diameter of the cable or to a lesser one without the proper function being risky. The electric charge on the insulation system decreases as a consequence of the fact that the inner and outer layers of the semiconductor material around the insulation will tend to form substantially equipotential surfaces and in this way the electric field in the insulation will be appropriately distributed relatively uniformly. the thickness of the insulation. It is known, per se, in connection with transmission cables for high voltage and for transmission of electrical energy, to design the conductors with an insulation of a solid insulation material with inner and outer layers of semiconductor material. In the transmission of electrical power, it has long been noted that the insulation should be free of defects. However, in high voltage cables for transmission, the electrical potential does not change along the length of the cable but the potential is basically at the same level. Nevertheless, also in high-voltage cables for transmission, instantaneous differences in potential can happen due to transient events such as lightning. According to the present invention a fl exible cable according to the appended claims is used as a winding in the electromagnetic device. A further improvement can be achieved by constructing the electrical conductor in the winding from smaller wires, at least some of which are insulated from each other. By making these yarns have a relatively small cross-section, preferably of approximately circular shape, the magnetic field across the yarns will show a constant geometry in relation to the field and the effects of parasitic currents are minimized. According to the invention, the winding or windings is thus preferably made in the form of a cable comprising at least one conductor and the insulation arrangement described above, the inner layer of which extends around the wires of the conductor. Outside the internal semiconductor layer, the main insulation of the cable is arranged in the form of a solid insulation material. The semiconductor outer layer will show according to the invention such electrical properties that ensure that an equalized potential is secured along the conductor. The outer layer may, however, not exhibit such conductivity properties that an induced current will flow along the surface, which could cause losses which in turn can create an undesired thermal load. The resistance (at 20 ° C) defined in the appended claims 5 and 6 is valid for the internal and external layers. With respect to the internal semiconductor layer, it must have sufficient electrical conductivity to ensure a potential equalization for the electric field but at the same time this layer must have a resistivity such that the enclosure of the electric field is ensured. It is important that the inner layer uniform the irregularities in the surface of the conductor and form an equipotential surface with a high surface finish at the interface with the solid insulation. The inner layer can be formed with a variable thickness but must ensure a uniform surface with respect to the conductor and solid insulation, a thickness between 0.5 and 1 mm being suitable. The aforementioned flexible winding cable which is used according to the invention in the electromagnetic device thereof is an improvement of an XLPE cable, cross-linked polyethylene, or a cable with an insulation of EP rubber, ethylene-propylene, or other rubber, for example silicone. The improvement comprises, among other things, a new design both with respect to the wires of the conductors and in that the cable, at least in some embodiments, does not have an external sheath for mechanical protection of the cable. However, it is possible according to the invention to provide a conductive metallic sheath and an outer sheath disposed outside the outer semiconductive layer. The metallic sheath will then have the character of external, mechanical and electrical protection, for example for lightning and lightning. It is preferred that the semiconductor inner layer be supported on the potential of the electrical conductor. For this purpose at least one of the wires of the electrical conductor will be uninsulated and will be arranged in such a way as to obtain a good electrical contact with the internal semiconductor layer. Alternatively, different wires may alternatively be brought into electrical contact with the inner semiconductor layer. The decisive advantage with the winding cable formed according to the invention is that the electric field is attached to the winding so it will not be externally electric field of the outer semiconductor layer. The electric field obtained only occurs in the solid main insulation. A thermally reduced charge is obtained sc re the stator. Temporary overloads of the machine will be, in this way, less critical and it will be possible to operate the machine with overload for a longer period of time without risking damage. This means considerable advantages for the owners of power generating plants who today are forced, in the case of operational alterations, to switch quickly to other equipment, in order to ensure the supply requirements imposed by law. With a rotary electric machine according to the invention, the maintenance costs can be significantly reduced because the circuit rotors and transformers do not have to be included in the arrangement for connecting the machine to the power grid. It has been previously described that the semiconductor outer layer of the winding cable is connected to a ground potential. The purpose is that the layer should be substantially maintained at an earth potential along the full length of the winding cable. It is possible to split the outer semiconductor layer by cutting it into a number of parts distributed along the length of the winding cable, each individual layer part being directly connectable to the ground potential. In this way, a better uniformity is achieved along the length of the winding cable. It has been previously mentioned that solid insulation and inner and outer layers can be achieved, for example, by extrusion. However, it is also possible to use other techniques, for example, by forming these inner and outer layers and insulating by means of spraying the material in question over the conductor or coil. It is preferred that the winding cable be designed with a circular cross section. However, other cross sections can be used in cases where it is desired to achieve a better packing density. To achieve the voltage in the rotating electrical machine, the cable is arranged in several consecutive turns in grooves in the magnetic core. The winding can be designed as a winding of concentric cables in multiple layers to reduce the number of extreme windings. The cable can be made with a tapered insulation to utilize the magnetic core in a better shape, in which case the shape of the slot can be adapted to the tapered insulation of the bobbin. A significant advantage with a rotary electric machine according to the invention is that the field E is close to zero in the region of the coil end outside the external semiconductor and that with the outer shell at a potential to ground, the electric field it does not need to be controlled. This means that field concentrations can not be obtained either within the sheets, in the end regions of the coil or in the transition between them. To summarize, an electrical ototative machine according to the present invention has a considerable number of important advantages in relation to the corresponding machines of the prior art. Firstly, a power network of all types of high voltage can be connected directly. Another important advantage is that a chosen potential, for example a ground potential, has been consistently driven along the entire winding, which means that the winding region can be made compact and that the clamp means in the coil end region they can be applied with virtually ground potential or any other chosen potential. Yet another important advantage is that the oil-based cooling and insulation arrangements also disappear in the rotating electric machines as set forth above. This means that the sealing problems no longer occur and that the aforementioned dielectric ring is not needed. An advantage is also that all forced cooling can be done with a ground potential.

BRIEF DESCRIPTION OF THE DRAWINGS With reference to the attached drawings, a more specific description of the embodiments of the invention will be given below. In the drawings: Figure 1 is a partially sectioned view showing the parts included in a modified standard power cable; Figure 2 is an axial end view of a sector / pole passage of a magnetic circuit according to the invention; Figure 3 is a diagrammatic view illustrating the prior art, that is, a multiplier transformer coupled between a generator and an associated switching mechanism; Figure 4 is a view illustrating a device according to the invention with a downstream transformer removed; Figure 5 is a perspective view illustrating a conventional generator plant. Figure 6 is a similar view illustrating simplification achieved as a consequence of the use of the invention. Figure 7 is an online diagram with respect to static variable compensation (SVC) and a switching mechanism according to the prior art; Figure 8 is a diagram of a line with respect to an embodiment according to the invention as a contrast to the conventional embodiment to Figure 7; Figure 9 is a diagram of a line with respect to a switching mechanism station according to the prior art provided with a static converter in "opposite to opposite" design with a DC link; and Figure 10 is a diagram of a line illustrating, in contrast to an earlier embodiment according to Figure 9 as a switching mechanism station according to the invention having a rotation converter that becomes much simpler and requires less amount of space as compared to the station according to Figure 9 that has a static converter.

DESCRIPTION OF THE PREFERRED MODALITIES An important condition for manufacturing a magnetic circuit according to the description of the invention is to use for the winding a conductive cable with a solid electrical insulation with an internal semiconductor layer or cover or shell between the insulation and one or more electrical conductors located internally with respect to the isma and with an external semi-conductor layer or cover or casing located outside the insulation. Such cables are conventional cables and available in the market for other fields of energy engineering use, for example in power transmission. To describe an embodiment, a brief description of a conventional cable will be initiated. The internal conductor carrying current comprises a number of non-isolated wires. An inner semiconducting layer is provided around the threads. Around this semiconducting inner layer, an insulating layer of solid insulation is provided. The solid insulation consists of a polymeric material with low electrical losses and a high improvement in strength. As concrete examples, mention may be made of polyethylene and then particularly crosslinked polyethylene and ethylene-propylene. A metal sheath and an outer insulation shell can be provided around the semiconductor outer layer. The semiconductor layers consist of a polymeric material, for example, eru i -copolymer, with an electrically conductive constituent, for example, carbon black or conductive soot. The mentioned cable will be indicated hereinafter as power cable. A preferred embodiment of a cable for a winding in a rotary electric machine is shown in Figure 1. The cable 1 is described in the Figure as comprising an energy carrying conductor 2 comprising transposed uninsulated and insulated wires. It is also possible to use insulated and electromechanically transposed extruded wires. These threads can be transposed or spun according to a plurality of layers. A semiconductor inner layer 3 is provided around the conductor which, in turn, is surrounded by a homogeneous layer of a solid insulating material. The insulation 4 completely lacks insulation material of the liquid or gaseous type. This layer 4 is surrounded by an outer semiconductive layer 5. The cable used as a coil in the preferred embodiment may be provided with a metal shield and an outer sheath but may not be so pro ssed. To avoid induced currents and losses associated therewith in the external semiconductor device 5, it is cut off, preferably at the coil end, that is, in transitions in the stack of foils in the end coils. The cutting is carried out in such a way that the outer semiconductor layer 5 will be divided into several parts distributed along the cable and electrically completely or partially separated from each other. Each cutting part is then connected to ground, such that the outer semiconductor layer 5 will be maintained at a ground potential, or close to ground, over the entire length of the cable. This means that, around the solid insulated winding at the coil ends, the contact surfaces, and the surfaces that become dirty after some time of use, will only have negligible earth potentials, and they will cause only negligible electric fields. To optimize a rotating electric machine, the design of the magnetic circuit in terms of grooves and teeth, respectively, is of decisive importance. As mentioned above, the grooves should connect as closely as possible to the cover of the coil sides. It is also desirable that the teeth at each radial level be as wide as possible. This is important to minimize losses, the magnetization requirement, etc. of the machine. With access to the conductor for the winding, such as, for example, the cable described above, there are great possibilities to optimize the magnetic core from various points of view. In the following, a magnetic circuit in the stator of the rotating electric machine is indicated in Figure 2 and shows an embodiment of an axial end view of a sector / pole step 6 of a machine according to the invention. The rotor with the pole of the rotor is indicated with the number 7. In a conventional manner, the stator is composed of a laminated core of electric sheets or sheets composed successively of leaves or sheets in the form of a sector. From a rear portion 8 of the core, located at the radially outermost end, a number of teeth 9 extends radially inwardly towards the rotor. A corresponding number of grooves 10 are disposed between the teeth. The use of cables 11 according to the above described among other things allows the depth of the grooves for altemator machines to be larger than what is possible in accordance with the state of the art. The grooves have a cross section that is tuned towards the rotor since the need for cable insulation becomes less for each winding layer towards the air gap. As is clear from the Figure, the groove substantially consists of a circular cross section 12 around each layer of the winding with constricting portions 13 between the layers. With some justification, each slot cross section can be indicated as a "cycle chain slot". In the embodiment shown in Figure 2, cables with three different dimensions of cable insulation are used, arranged in three correspondingly dimensioned sections 14, 15 and 16, that is, in practice a modified cycle chain slot will be obtained. . The Figure also shows that the teeth of the stator can be formed with a practically constant radial width along the depth of the entire groove. In an alternative embodiment, the cable that is used as a winding can be a conventional power cable such as that described above. The grounding of the external semiconductor shield is then carried out by removing the metal shield and cable shield at suitable locations. The scope of the invention allows a large number of alternative embodiments, depending on the available dimensions of the cable in regard to the insulation and the outer semiconductor layer, etc. Also the embodiments with the so-called cycle chain slots can be modified in excess of what has been described herein. As mentioned above, the magnetic circuit can be located in the stator and / or? rotor of the rotating electric machine. However, the design of the magnetic circuit will largely correspond to the above description irrespective of whether the magnetic circuit is located in the stator and / or in the rotor. As a winding, a winding is preferred which is described as a multi-layer concentric cable winding. Said coiling means that a number of cores at the ends of the coil has been minimized by arranging all the coils within the same group radially outwardly with respect to each other. This also allows a simpler method for the manufacture and threading of the winding in the stator, in the different slots. Since the cable used according to the invention is relatively easy flexible, the winding can be obtained by a comparatively simple threading operation, in which the flexible cable is threaded into the openings 12 present in the slots 10. The The previous solution illustrated in Figure 3 comprises a conventional generator 20: This generator feeds, by means of a switch 23, a generator transformer or a so-called multiplier transformer. The latter occurs since the conventional generator 20 generates voltage at a relatively low level. The transformer 21 is required to drive transmission losses, i.e. to increase the voltage to a required extent. The high-voltage switch mechanism is referred to as 22. Between the generator and the transformer as well as between the transformer and the interrupting mechanism switches 23 and 24 respectively are coupled. A disconnect is referred to as 25. the conventional current and the voltage transformers 26 and 27 respectively serve to measure the purposes that occur in a conventional manner. The generator 20 is coordinated with an excitation transformer 28. An auxiliary power transformer is designated at 30. It is connected to an auxiliary power switching mechanism 31.

For the rest, conventional overvoltage deviators serve for overvoltage protection to occur. The ground means are denoted at 33. Figure 4 illustrates a switching mechanism station according to the invention. A high voltage generator 34 provided with one or more windings according to the present invention is in such high voltage that it can be directly connected to the distribution or transmission network in question by the high voltage switching mechanism 35. In this way this means that the multiplier transformer according to the embodiment in figure 3 is not required. A drastic simpli ication of the interruption mechanism status is the result. Some additional differences occur. The auxiliary power transformer that occurs in the mode according to Figure 3 is placed by an auxiliary power winding in the generator 34. For the rest, the noble difference is that a particular protection device 36 has been added to the line between the generator and the high-voltage switching mechanism. This protection device is intended to operate as a current limit. More specifically, this overcurrent limiting function occurs by the device forming a low impedance current path to grow in the case of an error that has to be detected. Since the transformer 21 occurs in the mode according to figure 3 which has been eliminated in the mode according to figure 4, a possible failure occurs, for example in the insulation system of the generator 34, will cause the complete energy of the network to charge the generator for at least some time before the interruption of the circuit having dead time occurs. The divergent overcurrent device 36 is intended to operate substantially faster as it deviates the overcurrent in this path and avoids the same full influence of the generator 34. Furthermore, it is preferable that a limiting reactor current be provided in the line between the generator 34 and the high-voltage switching mechanism 35, the reactor has the property of restricting the over-current in case of failure causing such overcurrents. According to a preferred embodiment, the current limiting reactor is placed on the line 37 between the generator 34 and the high-voltage switching mechanism 35 so that the limiting reactor current is placed between the diverging overcurrent device connection in line 37 and 1 generator 34, that is, such that the reactor will operate by limiting the current for power cuts to flow from the network in a direction toward the generator in case of any failure in the same. Figure 5 illustrates a perspective view of a conventional switching mechanism station comprising two generators 38 each powered, by means of high current bars 39 and a module 40 of current switching mechanism, fed from a multiplied transformer 41 , the transformer in turn being connected to the high voltage switching mechanism 42. In addition, auxiliary equipment such as auxiliary power transformers, etc., are added. Furthermore, it is pointed out that the transformers 41 which are of a conventional oil filling mode, require separation of sparks in the form of walls etc. and safety measures in the form of oil collection plants. As can be seen, the station as a whole is extremely complex and expensive. It was mentioned that the oil-isolating transformers 41 are placed outside the construction 43 which contains the generators due to the dangerous associated sparks dangerous to the oil filling transformers. Figure 6 illustrates the use of the invention, ie the direct connection of the high voltage generators 44 directly to the networks of energy without intermediate multiplier transformers. As explained in the above, the key to this possibility is the design of the windings of the generators. It is indicated in FIG. 6 that the cables 45 start from the generators 44 extended to the high voltage switching mechanism 46. The very simple connection between the generators and the network by means of a high-voltage cable drastically reduces the cost as compared in the more expensive equipment required in the modality according to Figure 3. In addition, transformers, etc. they can be eliminated. The design according to Figure 6 is substantially more environmentally friendly since the transformed oil can be completely avoided. Also the dangerous sparks are reduced remarkably.

Figure 7 illustrates a conventional modality for Static VAR Compensation (SVC) and a switching mechanism. An SVC station typically consists of switching devices in the high voltage interrupting mechanism 47, a transformer 48 transforms the voltage to below a level that the thyristors 49, 50 can handle, reactors, capacitors and double direction thyristor valves. More transmission applications require an automatic voltage regulator (AVR) such as thyristor-driven. A disadvantage with this plant is that many appliances are required and occupy a large space. Figure 8 illustrates a station according to the invention having a rotating synchronous compensator and a switch mechanism 52. The transformer is not required between the synchronous compensator and the high voltage switching mechanism since the synchronous compensator 51 is designed so that it can handle the transmission voltage in question. Which is a consequence of the fact that the synchronous compensator winding is being achieved by means of a cable according to the invention.

As is apparent from Figure 8, the modality becomes much simpler than one in Figure 7 and also requires less space. Figure 9 illustrates a conventional switching mechanism station provided with a static converter in opposite to opposite design having a DC link. As can be seen, an important disadvantage with this type of station is that the required surface becomes long, mainly as a consequence of the number of filters. Transformers are complicated and particularly adapted to these latents. Figure 10 illustrates a diagram of a switching mechanism station comprising rotary converters 53. Each of these converters consists of a motor / generator provided with a winding according to the description given in the foregoing. The mode according to FIG. 10 is particularly suitable when communication is being established between two different networks having different parameters in a few respects. For example, the network 54 may be at a different voltage level, a different phase position, a different frequency or have a different number of phases than the second network 55 AC. The connection illustrated in the networks by means of motors / generators where one of the units 53 will trigger the other solutions of a communication problem without causing any alteration between the networks. As in the above, the mechanisms 56 of high voltage interruption and several switches, etc. , provoked. The protection device 36 described more closely with the aid in the embodiment of Figure 4 also occurs here and more specifically in a double set under the designation 57 on either side of the motor / generator pair. In this way, the protection devices 57 will protect the pair of motors / generators of both networks 54, 55. For the rest, the constituents already explained by drawings of previous figures also occur here. It is apparent from the above description that the switching mechanism station according to the invention involves various advantages over the prior art in a number of different embodiments of rotating electric machines comprising magnetic circuits. The basic disadvantages with the invention have already been negotiated with the aforementioned. As an additional point it should also be emphasized that this is of considerable importance that the design according to the invention of the winding of the machine will result in a cemented improvement to the commutation mechanism station as a consequence of the low magnetic and electric field around of the machine and in particular in its cable connection.

POSSIBLE MODIFICATIONS It is evident that the invention is not limited only in the modalities illustrated in the above. In a manner, the expert in this art will make a number of detailed modifications which are possible. The basic concept of the invention has been presented without deviating from the concept as defined in the close claims. As an example, it is pointed out that the invention is not only restricted to the selection of specific material exemplified in the foregoing, the functionality of the same materials can, consequently, be already used. As far as the manufacture of the insulation system according to the invention is concerned, other extrusion and ulverization techniques are also possible, as well as the familiarity between the different layers is achieved. In addition, it is noted that the additional equipotential layers could be coupled. For example, one or more equipotential layers of semiconductor material will be placed in the insulation between those layers designated as "internal" and "external" in the foregoing.

Claims (31)

1. Switching mechanism station comprising at least one switching mechanism and at least one high voltage rotating electrical machine, the machine comprises at least one winding including at least one electrical conductor and an isolation system including a insulation formed by a solid insulation material, characterized in that the insulation system internally of the insulation comprises an inner layer having an electrical conductivity that is less than the conductivity of the electrical conductor but sufficient to cause the inner layer to operate for the equalization of the potential and, consequently, the equalization as concerns the electric field externally in the inner layer. The insulation system comprises, externally of the insulation, an outer layer having an electrical conductivity that is greater than that of the insulation which makes the outer layer capable, by grounding or otherwise a relatively low potential, of operation at equal potential, and substantially the near electric field, arises as a consequence of the electrical conductor, inside the outer layer.

2. Station according to the claim 1, characterized in that at least one conductor forms at least one induction rotation.

3. Station according to claim 1 or 2, characterized in that the inner and / or outer layer comprises a semiconductor material.

4. Station according to the preceding claims, characterized in that the inner layer and / or the outer layer has a range in the range of 10"6 Ocm- 100 Ocm, suitably 10" 3-1000 O cm, preferably 1 500 Ocm, and in particular 10-200 Ocm.

5. Station according to the preceding claims, characterized in that the inner layer and / or the outer layer has a resistance that per meter of length of the conductive system / insulation is in the range of 50 μO 5 MO.

6 Station according to any of the preceding claims, characterized in that the solid insulation, the inner layer and / or the outer layer are formed by polymeric materials.

7. Station according to any of the preceding claims, characterized in that the inner layer and / or the outer layer and the solid insulation are rigidly connected together on substantially the entire interface to ensure the adherence between the respective layers and the solid insulation at changes of temperature and bending of the conductor and its insulation system.

8. Station according to any of the preceding claims, characterized in that the inter-layer, the outer layer and the solid insulation are formed by materials having substantially equal thermal coefficients of ion expansions.

9. Station according to any of the preceding claims, characterized in that the inner layer and the outer layer are achieved by extrusion simultaneously with the extrusion of the rigid insulation.

10. Station according to any of the preceding claims, characterized in that the conductor and its isolation system constitute a winding formed by means of a flexible cable.

11. Station according to any of the preceding claims, characterized in that the inner layer is in electrical contact with at least one electrical conductor.

12. Station according to the claim 11, characterized in that at least one electrical conductor comprises a number of strands and at least one strand of the electrical conductor is at least partly not insulated and coupled in an electrical contact with the inner layer.

13. Station according to any of the preceding claims, characterized in that the inner and outer layers and the insulation are made of materials having an elasticity to that of the layers that maintain or adherence to the rigid insulation despite the temperature variations that occur under the operation.

14. Station according to claim 13, characterized in that the materials, the layers and the solid insulation have an E module that is less than 500 MPA, preferably less than 200 MPA.

15. Station according to any of claims 13 and 14, characterized in that the adhesion between the layers and the insulation is at least in the same order as in the weakness of the materials.

16. Station according to any of the preceding claims, characterized in that the conductor and its isolation system are designed by high voltage, suitably in excess of 10 kV, in particular in excess of 36 kV and preferably more than 72.5 k.

17. Station according to any one of the preceding claims, characterized in that the external Aapa is divided into a number of parts, which are connected to ground or otherwise at a low potential in their own age.

18. Station according to the rei indication 1, characterized in that at least one winding is coupled in the stator and / or rotor of the machine.

19. Station according to claims 1 to 18, characterized in that the magnetic field generating circuit comprises one or more magnetic cores having grooves for the winding.

20. Station according to claims 18-19, characterized in that in relation to the outer layer the potential growth, the electric field of the machine outside the outer layer will be close to zero both in the groove and in the end region of the roll.

21. Station according to any of claims 18-20, characterized in that the slots are formed as a number of currently extended cylindrical openings coupled radially outwardly from each other and separated by a narrower middle portion between the openings. .

22. Station according to claim 21, characterized in that the transverse section of the slit openings decreases, counted from a rear portion of the magnetic core.

23. Station according to claim 22, characterized in that the transverse section of the grooves decreases continuously or discontinuously.

24. Station according to any of claims 18-23, characterized in that the machine is made up of a generator, motor or synchronous compensator.

25. Station according to claim 24, characterized in that the generator is a liidrogenerator or turbo generator.

26. Station according to any of claims 1-25, characterized in that the machine is directly connected to a power grid for high voltage, suitably 36 kV and more, without intermediate transformer.

27. Station according to claim 29, characterized in that the rotating electrical machine is connected to the switching mechanism by one or more flexible cables forming continuations of the winding in the machine.

28. Station according to the claim 24 and 26, characterized in that the machine is connected to. a distribution or transmission network through the switching mechanism.

29. Station according to any of the preceding claims, characterized in that the rotating electric machine is formed by a rotary synchronous converter or an asynchronous converter.

30. Station according to any of the preceding claims, characterized in that an overcurrent divergent device is connected to a line between the rotating electrical machine and the switching mechanism to deflect, in the event of a fault, overcurrents is possible to the ground or otherwise a low potential.

31. Station according to any of the preceding claims, characterized in that the current limiting reactor is connected to a line between the rotating electrical machine and the switching mechanism in order to limit the overcurrents caused by a fault.