EA002309B1 - Electromagnetic device - Google Patents

Abstract

1. Electromagnetic device comprising at least one magnetic circuit (1) and at least one electric circuit (2, 3) comprising at least one winding (4, 5), the magnetic and electric circuits being inductively connected to each other and the device comprising a control arrangement (7) to control operation of the device, characterized in that the control arrangement (7) is adapted to control frequency, amplitude and/or phase as concerns electric power to/from the device by the control arrangement comprising means (9) for controlling the magnetic flux in the magnetic circuit, and that said at least one winding (4, 5) or at least a part thereof comprises at least one electric conductor (42) having an insulation system comprising an electric insulation (44) formed by a solid insulation material and interiorly thereof an inner layer (43), that said at least one electric conductor (42) is arranged interiorly of the inner layer (43) and that the inner layer has an electrical conductivity which is lower than the conductivity of the electric conductor but sufficient to cause the inner layer (43) to operate for equalization as concerns the electrical field exteriorly of the inner layer. 2. A device according to claim 1, characterized in that the control means comprises at least one control winding (9) inductively connected to the magnetic circuit. 3. A device according to claim 1 or 2, characterized in that the control arrangement (7) is adapted to control the reluctance in the magnetic circuit. 4. A device according to any preceding claim, characterized in that the control arrangement is adapted to add a magnetic flux addition to the magnetic flux in the magnetic circuit. 5. A device according to claim 3, characterized in that material having a permeability greater than 1 is included in the magnetic circuit and that the control arrangement (7) is adapted to control the reluctance in the magnetic circuit by varying the permeability of one or more such zones of the magnetic circuit which have variable permeability. 6. A device according to claim 5, characterized in that the zone or zones having a variable permeability comprise one or more gaps in the magnetic circuit. 7. A device according to any preceding claim, characterized in that the magnetic circuit is without magnetic core. 8. A device according to any of claims 1-6, characterized in that the winding is wound about a magnetic core (6). 9. A device according to claim 2-8, characterized in that the control winding (9) and the winding (4, 5) of the electric circuit are arranged to be passed by substantially the same magnetic flux. 10. A device according to any preceding claim, characterized in that the device forms a reactor adapted to control, by means of said at least one control winding, frequency, amplitude and/or phase as concerns the electric power flowing in the winding (4, 5) of the electric circuit. 11. A device according to any of claims 1-8 or 10, characterized in that the electric circuit (2) comprises at least two windings (23, 24) coupled in series, that the magnetic circuit comprises at least two alternative flux paths (18, 19), that said at least one control winding is adapted to control the magnetic flux to pass in any of or both of these flux paths and that the two windings of the electric circuit are located such that one of them is capable of being switched off from magnetic flux by means of said at least one control winding. 12. A device according to any of claims 1-9 or 11, characterized in that the magnetic circuit is arranged in the stator or rotor of a rotating electric machine. 13. A device according to any of claims 1-9, characterized in that the magnetic circuit (1) belongs to a transformer having primary and secondary windings (4, 5) and that the primary and secondary windings and the control winding (9) are arranged to be passed by the same magnetic flux. 14. A device according to any of claims 1-8, characterized in that the secondary winding of the transformer comprises at least two winding parts coupled in series, that the magnetic circuit comprises at least two alternative flux paths (18, 19), that at least two occurring control windings (9b1, 9b2, 9c1, 9c2) are adapted to control the magnetic flux to pass in one or both of these paths and that the two winding parts of he secondary winding are placed such that one of them is capable of being switched off from magnetic flux by means of the control windings. 15. A device according to any of claims 11 and 14, characterized in that it comprises a magnetic core having at least three legs coupled in parallel and that two of these legs belong to different flux paths whereas the third is common to the two flux paths. 16. A device according to any preceding claim, characterized in that the insulation system exteriorly of the insulation comprises an outer layer (45) which has an electrical conductivity which is higher than that of the insulation to make the outer layer capable, by connection to earth or otherwise a relatively low potential, of operating to equalize potential. 17. A device according to any preceding claim, characterized in that the outer layer is arranged to substantially enclose the electric field, arising as a consequence of said electrical conductor (42), inwardly of the outer layer (45). 18. A device according to any preceding claim, characterized in that the inner layer (43) and the solid insulation present substantially equal thermal properties. 19. A device according to any preceding claim, characterized in that the outer layer (45) and the solid insulation present substantially equal thermal properties. 20. A device according to any preceding claim, characterized in that said at least one conductor (42) forms at least one induction turn. 21. A device according to any preceding claim, characterized in that the inner layer (43) and/or the outer layer (45) has a resistivity in the range 10<-6> ncm-100 kQcm, suitably 10<-3>-1000 Qcm, preferably 1-500 Qcm. 22. A device according to any preceding claim, characterized in that the inner layer (43) and/or the outer layer (55) has a resistance which per length meter of the conductor/insulation system is in the range 50 ptQ - 5 MQ. 23. A device according to any preceding claim, characterized in that the solid insulation (44) and the inner layer (43) and/or the outer layer (45) are formed by polymeric materials. 24. A device according to any preceding claim, characterized in that the inner layer (43) and/or the outer layer (45) and the solid insulation (44) are rigidly connected to each other over substantially the entire interface to ensure adherence also on flexing and temperature change. 25. A device according to any preceding claim, characterized in that the solid insulation and the inner layer and/or the outer layer are formed by materials having a high elasticity to maintain mutual adherence on strains during operation. 26. A device according to any preceding claim, characterized in that the solid insulation and the inner layer and/or the outer layer are formed by materials having substantially equal Emodulus. 27. A device according to any preceding claim, characterized in that the inner layer (43) and/or the outer layer (45) and the solid insulation (44) are formed by materials presenting substantially equal thermal coefficients of expansion. 28. A device according to any preceding claim, characterized in that the conductor (42) and its insulation system constitutes a winding formed by means of a flexible cable (41). 29. A device according to any preceding claim, characterized in that the inner layer (43) is in electric contact with the at least one electric conductor (42). 30. A device according to claim 29, characterized in that said at least one electric conductor (42) comprises a number of strands and that at least one strand of the electric conductor (42) is at least in part uninsulated and arranged in electric contact with the internal layer (43). 31. A device according to any preceding claim, characterized in that the conductor (42) and its insulation system is designed for high voltage, suitably in excess of 10 kV, in particular in excess of 36 kV and preferably more than 72,5 kV. 32. A machine according to claim 12, characterized in that the magnetic circuit comprises one or more magnetic cores (48) having slots (50) for the winding (41). 33. A device according to any of claims 12 and 31-32, characterized in that it is constituted of a generator, motor or synchronous compensator. 34. A device according to any of claims 12 and 32-33, characterized in that it is directly connected to a power network for high voltage, suitably 36 kV and more, without intermediate transformer. 35. A device according to any of claims 1-11 and 13-31, characterized in that it is constituted by a power transformer/reactor.

Description

The present invention relates to an electromagnetic device comprising at least one magnetic circuit and at least one electrical circuit including at least one winding, said circuit being inductively coupled to each other, and the device contains a control circuit for management of its work.

Electromagnetic device can be used in any electrical circuit. It can operate in the power range from VA to 1000 MVA. High voltages are used, among other applications, in modern high-voltage power lines.

In accordance with the first aspect of the invention, a rotating electrical machine is contemplated. Such electrical machines include synchronous machines, mainly used as generators in distribution and transmission networks, referred to below as power grids or power grids. Synchronous machines are also used as motors, as well as for phase compensation and voltage regulation when used as idling machines. Such machines belong to the field of technology, also covering machines with dual power, asynchronous converter cascades, machines with explicit poles, machines with synchronous magnetic fluxes and asynchronous padins.

In accordance with the second aspect of the invention, the electromagnetic device is constituted by a power transformer or reactor. Transformers are used in all systems of distribution and transmission of electricity, and they serve to exchange electricity between two or more power systems, for which they apply the well-known electromagnetic induction. The transformers belonging to the present invention belong to the class of so-called power transformers with a rated power from several hundred KVA to more than 1000 MVA and a rated voltage from 3-4 kV to very high transmitted voltages - from 400 to 800 kV or higher.

Although the following description of the prior art relating to the second aspect of the invention mainly concerns power transformers, the present invention is also applicable to reactors that may be single phase or three phase. As for the insulation and cooling of reactors, they are the same as for transformers. Thus, the invention is applicable to air and oil insulated, self-cooled, oil-cooled, pressurized, etc. reactors. Although the reactors have one winding per phase and can be with and without a magnetic core, the description of the prior art, however, to a large extent also applies to reactors.

At least one winding of the electric charge may be in some embodiments of air-mounted, i.e. without a core, but, as a rule, such a winding includes a magnetic core from a package of ordinary or oriented plates or from another, for example, amorphous or powder-based material, providing a variable magnetic flux, and the winding itself. A transformer based on such a circuit is often provided with some kind of cooling system. In the case of a rotating electric machine, the winding may be located in the stator or rotor, or both.

The problem with the known structures of electromagnetic devices of the mentioned type is that it is relatively difficult to ensure effective regulation of a number of certain parameters, and that such control (control) circuits are relatively expensive. It is known to provide a generator of a control circuit for operating parameters using an excitation winding. If the rotor contains electromagnets, this excitation winding is performed on the rotor, which increases the cost and complicates the design. If the rotor contains permanent magnets, such control using the excitation winding is practically impossible. All this, of course, in general, complicates the implementation of such management in general, as well as particularly delicate regulation, in particular.

The problem of the known devices is also that the manufacturing technology of the windings is expensive. In known devices there are significant energy losses, which is associated with some restrictions on the location of the windings in the magnetic circuit.

Summary of the Invention

The present invention is the creation of ways to simplify and improve the controlled operation of electromagnetic devices, in accordance with the restrictive part of the attached claim 1 of the claims, as well as improving the conditions for the rational manufacture and installation of windings.

The main objective of the present invention is solved using a control circuit containing means for controlling the magnetic flux in the magnetic circuit in order to control the frequency, amplitude and / or phase related to the energy supplied to the device and diverted from it.

Thus, the basic concept of the present invention is to create the ability to control the operation of the device by directly influencing the magnetic flux in the magnetic circuit. This allows you to create a very rational and inexpensive design of the device and, in addition, to obtain increased control capabilities of the device with a view to its optimal operation.

In accordance with a particularly preferred embodiment of the invention, the control means comprise at least one control winding inductively coupled to the magnetic circuit. Accordingly, the control circuit can operate through the control winding, with the required control of the magnetic flux in the magnetic circuit through the said winding by applying through the latter such control parameters that affect the magnetic flux to the desired degree. The control winding may even be short-circuited. In such cases, the magnetic flux in certain embodiments may not pass through this winding. Depending on the circuit of the magnetic circuit, partial or complete blocking of the magnetic flux may occur.

Examples of control functions that can be obtained by using the present invention are voltage variation and voltage stabilization, elimination of transients, damping of energy parameter fluctuations in the power system, harmonic filtering, frequency control and phase control (separate control for phases is provided). The control circuit in accordance with the invention can be adapted to increase the magnetic flux in the magnetic circuit, i.e. control circuit can work with direct energy supply.

The control of the magnetic flux in the magnetic circuit, in accordance with the invention, for example, in a transformer, means that the required control of the voltage of the secondary winding is possible, despite undesired fluctuations of the primary voltage or the load on the secondary winding.

Other details and advantages of magnetic flux control in a magnetic circuit will be more apparent from the following detailed description.

Also, in accordance with the invention, at least one of the windings of the electromagnetic device, or at least part of such a winding, contains at least one flexible electrical conductor having a shell that, having magnetic permeability, is capable of enclose an electric field existing around a conductor. In other words, this means that the flexible conductor and its sheath (in the form of an insulation system) are a flexible cable. This gives significant advantages in the manufacture and installation of such windings in comparison with the standard rigid windings of a given form, which have been manufactured so far. The insulation system in accordance with the invention does not contain, in addition, gaseous and liquid insulation materials.

Since the electric field existing around the conductor of the cable is essentially, in accordance with the invention, embedded in an insulation system, the losses occurring are so much so that the device can operate with higher efficiency. Reducing losses leads, in turn, to a decrease in the temperature of the device and, accordingly, to a reduction in the need for cooling, and allows the construction of simpler cooling devices than before the invention, possibly used.

As for the aspect of the invention relating to rotating electrical machines, it makes it possible for the machine to operate at such a high voltage that it does not need to use standard step-up transformers. This means that the machine can operate at a much higher voltage than the known machines, which allows you to directly turn on the machine in power networks. This implies a significant reduction in investment in systems with a rotating electric machine while increasing the overall efficiency of the entire system. The invention eliminates the need for separate control measurements of the field in certain areas of the winding, which were mandatory in the known devices. Another advantage of the invention is that it allows you to more easily provide bias and magnetization reversal, in order to reduce the reactive effects that occur when the voltage and current phases do not coincide with each other.

As for the aspect of the invention relating to the power transformer / reactor, it first of all eliminates the need to fill the power transformers with oil and, accordingly, the associated problems and disadvantages.

The winding design is such that it contains, at least along part of its length, insulation from a continuous insulating material, and inside the insulation is the inner layer, and outside its outer layer, both of which are made of semiconductor material, which allows to conclude the electric field devices inside the winding. The term “Continuous insulation material” as used herein means that the winding is not provided with liquid or gaseous insulation, for example, in the case of liquid in the form of oil. In the present case, the insulation is made of a polymeric material. These inner and outer layers are also made of polymeric, albeit semiconductor material.

The inner layer and solid insulation are rigidly connected to each other, essentially over the entire interface. The outer layer and solid insulation are also rigidly connected to each other, essentially over the entire interface between them. The inner layer, due to semiconductor properties, performs the function of equalizing the potential and, accordingly, equalizing the electric field outside this layer. The outer layer is also made of semiconductor material, while its electrical conductivity is at least higher than the insulation, as a result of which, when it is grounded or connected to a relatively low potential, it performs the function of equalizing the potential and, in essence, contains the electrical field of the conductor . On the other hand, the resistivity of the outer layer should be sufficient to minimize electrical losses in it.

The rigid relationship between the insulation material and the inner and outer semiconductor layers must be the same across the entire interface between them so that cavities, pores, etc., do not form along it. The high voltages used in the invention, and the electrical and thermal loads associated with them, induce very high demands on the insulating material. It is known that the so-called partial discharges (ΡΌ) are a serious problem for an insulating material in high-voltage installations. If cavities, pores, etc. appear in the insulating layer at high voltages, internal corona discharges can occur, causing a gradual weakening of the properties of the insulating material, followed, as a result, by electrical breakdown of the insulation. This can lead to serious malfunctions of the electromagnetic device. Thus, the insulation should be uniform.

The inner layer located inside the insulation must have a lower electrical conductivity than that of the conductor, but sufficient for this layer to perform the function of equalizing the potential and, accordingly, the electric field outside this layer. Such a function of the inner layer in combination with its rigid connection with the insulating material, practically over the entire surface of their section in the absence of the mentioned cavities, pores, etc. provides the same electric field outside the inner layer and minimal risk of partial discharges.

Preferably, the inner layer and solid insulation are made of materials with substantially equal thermal expansion coefficients. The same is preferable for the outer layer and solid insulation. This means that the inner and outer layers and continuous electrical insulation form an insulating system that, when temperature changes, will evenly, as a whole, expand and contract without any destruction or separation in the surface area of the interface, caused so far by temperature changes. Thus, tight surface contact is guaranteed between the surfaces of the inner and outer layers and continuous insulation, and conditions are created to maintain such contact for long working periods. The specified contact must also be guaranteed, i.e. adhesion between at least the inner layer and solid insulation, and preferably also between the outer layer and solid insulation when the conductor bends and the insulation system. It should be pointed out that the cable should have such bendability or flexibility so that when winding winding from it, the radius of curvature at its bend points is less than 25 cable diameters, preferably less than 15 diameters of it. Most preferably, the radius of curvature at the cable bend points is less or substantially equal to its 8 diameters.

It is important that the insulation system consists of materials with good elasticity. The modulus of elasticity (module) of the materials should be relatively low, i.e. The resistance of the material to deformation should be relatively low. In order to avoid dangerous shear stresses in the interface area between the different layers of the insulation system, it is preferable that the elasticity of these layers be substantially equal.

Due to the fact that the inner and outer layers of semiconductor material located inside and outside around the insulation will tend to form essentially equipotential surfaces (surfaces of equal potentials), and the electric field, as a result, will be distributed relatively evenly across the insulation thickness, the electrical load on insulation system will be reduced.

Known, in themselves, high-voltage cables for the transmission of electricity with conductors insulated from a solid material provided with an inner and outer layers of semiconductor material. It has long been known that there should be no defects in the insulation for conductors used for the transmission of electricity. However, in the high-voltage cables of the mentioned purpose, the electric potential does not change along the length of the cable, remaining mostly at the same level. However, however, in such high-voltage cables, due to short-term phenomena such as a discharge, an instantaneous potential difference may occur. In accordance with the present invention, as a coil in an electromagnetic device, a flexible cable is used, as defined by the appended claims.

Additional improvements can be achieved by making the conductor winding from smaller so-called cores, at least some of which are isolated from each other. Due to the implementation of the veins with a relatively small, preferably almost circular cross-section, the magnetic field penetrating them will have a constant configuration, and the cases of eddy currents will be minimized.

In accordance with the invention, the winding is made, preferably, in the form of a cable containing at least one conductor and an insulation system previously described here, the inner layer of which is located around the conductor core. Outside the specified inner semiconductor layer is the main insulation of the cable in the form of a solid insulating material.

The outer semiconductor layer shell, in accordance with the invention, has electrical properties that ensure potential equalization along the conductor. However, the outer layer may not have such electrically conductive properties, as a result of which the induced current will flow along the surface, which may cause losses, which in turn may create an undesirable thermal load. The magnitude of the resistance at 20 ° C of the inner and outer layers, defined in paragraphs. 22 and 23 of the claims are reasonable. The inner semiconductor layer must have sufficient electrical conductivity to ensure the equalization of the potentials of the electric field, but at the same time this layer must have such resistance to ensure the coverage of the electric field.

It is important that the inner layer aligns the irregularities on the surface of the conductor and forms a very clean finished equipotential surface (surface of equal potentials) near the interface with solid insulation. The inner layer can be made of variable thickness, but with a guaranteed smooth surface, bordering the conductor and solid insulation, with the corresponding thickness being 0.5-1 mm.

Such a flexible winding cable, which is used, in accordance with the invention, in an electromagnetic device, is an improvement of a cable with insulation made of mesh polyethylene (HEPE cable) or of ethylene-propylene rubber (EP rubber). The enhancement contains a new design of the cores of the conductors and cable, and the cable, in at least some embodiments, does not have an outer shell for its mechanical protection. However, the invention makes it possible to arrange a conductive metal screen and an outer shell outside the outer semiconductor layer. The metal screen will perform the function of external mechanical and electrical cable protection, for example, from discharges. Preferably, the inner semiconductor layer is located in the potential zone of the conductor. For this purpose, at least one of the conductor cores must not be insulated and positioned so that it has good electrical contact with the inner semiconductor layer. On the other hand, different cores may alternatively be placed in electrical contact with said inner layer.

The manufacture of transformer or reactor windings from said cable is associated with significant differences in the distribution of the electric field in standard power transformers / reactors and power transformer / reactor, in accordance with the invention, a significant advantage of the winding made of cable, in accordance with the invention, is that the electric field is enclosed in a winding and that the electric field is absent outside the outer semiconductor layer. The electric field created by the current-carrying conductor takes place only in continuous main insulation. From a constructive and production point of view, this provides the following significant advantages:

transformer windings can be made without taking into account any distribution of the electric field, and the movement of the cores mentioned in the description of the prior art does not apply;

the transformer core can be made without taking into account any distribution of the electric field;

oil is not required for electrical insulation of the winding, i.e. the environment surrounding the winding may be air;

there are no special connections required for electrical connection between the external connections of the transformer and directly connected coils / windings, since the electrical connection, in contrast to standard installations, is integrated with the winding;

The technology of production and testing of a power transformer, in accordance with the invention, is much simpler than that used for a standard power transformer / reactor, since in this case the impregnation, drying and vacuum treatments referred to with reference to the known device are not required, which significantly reduces the time to manufacture the transformer.

By applying the invention to a rotating electric machine, a substantially reduced thermal load on the stator is achieved. Thus, temporary overloads of the machine will be less critical, which will allow the machine to operate during an overload for a long period without the risk of malfunction. This gives significant advantages to the owners of power generating plants, which promptly, in the event of production disturbances, quickly connect the installation to other equipment, thereby meeting the requirements for energy supply established by law.

In the case of using a rotating electric machine, in accordance with the invention, operational costs can be significantly reduced, since transformers and circuit breakers are not included in the machine's connection circuit to the power grid.

It was mentioned above that the outer semiconductor layer of the winding cable is grounded, that is, it is connected to the ground potential. This is done to ensure that this layer is maintained mainly under the ground potential throughout the entire cable length. Separation of said outer layer is allowed by cutting it into a number of parts distributed along the length of the winding cable, with each individual part of this layer being grounded connecting to the ground potential. In this way, the best uniformity of cable grounding along its length is ensured.

As mentioned, solid insulation and the inner and outer layers can be obtained, for example, by extrusion. However, other methods of their manufacture can be used with success, for example, the formation of the mentioned layers and insulation by spraying the material on a conductor / winding.

Preferably, the winding cable has a circular cross section. However, if you want to achieve a better density of its installation, other sections can be used.

In order to increase the voltage in a rotating electric machine, the cable is placed in the slots of the magnetic core with several successive turns. In order to reduce the number of intersections at the ends of the coils, the winding can be made in the form of a multilayer concentric cable winding. The cable for better use of the magnetic core can be made with bevelled insulation, for which the shape of the grooves can be adjusted to the bevelled winding insulation.

A significant advantage of a rotating electric machine, in accordance with the invention, is that the earth field (E-field) in the area of the ends of the coils outside the outer semiconductor layer is close to zero, and that in the presence of an outer shell, which is under earth potential, the electric field does not require regulation. This means that the field is not concentrated either inside the plates or in the zones of the ends of the coils, or in the transitions between them.

When implementing the method of manufacturing a device in accordance with the present invention, the flexible cable is screwed into the holes of the slots of the magnetic core of a rotating electric machine, being used as a winding. Since the cable is flexible, it can be bent, which allows it to be placed in a coil in the form of several turns. In this case, the ends of the coils will be formed by the sections of the bending of the cables. The cable can also be articulated in such a way that its properties remain constant along its entire length. This method is much simpler than known methods. The so-called Rebel's rods are not flexible, but they can be given the desired shape. Used in the manufacture of modern rotating electrical machines, winding insulation and impregnating the turns of the coils are very complex and expensive manufacturing operations.

Summarizing, we can say that the electromagnetic device in the form of a rotating electric machine, in accordance with the invention, has a number of significant advantages compared with the corresponding known machines. First of all, it can be directly connected to the power grid at all levels of high voltage. Another important advantage is that the ground potential is sequentially distributed along at least part of the winding and, preferably, along the entire winding, so that the area of the ends of the coils can be made compact, and the mentioned fastening means in this area can be under earth potential. Another important advantage is that the rotating electrical machine does not require oil-based insulation and cooling systems, as discussed above for power transformers / reactors. This means no sealing problems and the rejection of the use of the above-mentioned dielectric ring. It is also important that all forced cooling can be carried out in the construction, induced under the earth potential.

Brief Description of the Drawings

Below will be given a more specific description of embodiments of the invention with reference to the attached drawings, in which FIG. 1 is a schematic of a device, in accordance with the invention, in the form of a transformer;

FIG. 2 is a diagram of a variant of the transformer;

FIG. 3 is a diagram of another variant of the transformer;

FIG. 4 is a schematic of an embodiment similar to that shown in FIG. 3, but related to the reactor;

FIG. 5 is a diagram of an embodiment of a generator;

FIG. 6 is a partially cut-away view illustrating elements contained in a modified electrical standard cable;

FIG. 7 is an axial view of the end of a sector or pole division of a magnetic peak, in accordance with the invention;

FIG. 8 is a view illustrating the distribution of the electric field around the winding of a standard power transformer / reactor;

FIG. 9 is a perspective view illustrating an embodiment of a power transformer in accordance with the invention;

FIG. 10 is a cross section of a cable modified with respect to the cable shown in FIG. 6 and containing several electrical conductors; and FIG. 11 is a cross section of another cable containing several conductors, but different from that of FIG. 10 designs.

Description of preferred embodiments

FIG. 1 shows a diagram of an electromagnetic device, which is a transformer. The transformer contains a magnetic circuit 1 and two electric circuits 2,3, each containing at least one winding 4 and 5, respectively.

The transformer also contains a core 6 of magnetic material. In order to reduce losses from eddy currents, the core consists of a corresponding package of magnetic plates. However, the core is not a necessary condition for carrying out the invention. Within the limits of the invention, an exemplary embodiment is possible with air winding i. E. without core. From this it follows that the term magnetic circuit should be interpreted in a broad sense. Accordingly, this term means no more than the magnetic field generated by the windings 4,5 can generate a magnetic flux.

The device in accordance with the invention, contains a circuit 7, designed to control the operation of the transformer. The control circuit 7 serves to control the frequency, amplitude and / or phase, which are related to the electrical energy at the output of the transformer.

Electrical circuit 2 forms the primary side and electrical circuit 3 the secondary side of the transformer. Accordingly, the power is removed from the device through the secondary circuit 3, to which the schematically shown load 8 is connected. This load can be arbitrary, for example, it can relate to the needs of the consumer or be distribution and transmission grids.

The control circuit 7 comprises means 9 for controlling the magnetic flux in the magnetic circuit 1. The means 9 include, for example, at least one control winding inductively connected to the magnetic circuit 1. In the illustrated embodiment of the invention (FIG. 1) the winding 9 is wound around core section 6. In a coreless transformer, the control winding 9 must interact with the primary and secondary windings 4 and 5, respectively, so that the magnetic flux induced in the magnetic circuit without a core is inductively coupled to hank 9.

The control circuit 7 in accordance with the preferred embodiment of the invention must be of the active type, i.e. the control circuit 7 must be actively controlled through the magnetic flux control winding 9 in the magnetic circuit 1 in order to obtain the desired result. The control circuit 7 preferably contains an external power source so that it can control the magnetic flux through the magnetic circuit 1, causing current through the winding 9. The invention is particularly preferable in cases where high voltage is required. Accordingly, this means that electrical circuits 2 and 3 usually operate at relatively high voltages. However, for control purposes, it is sufficient that the control circuit 7 generates a current in the winding 9 at a relatively low voltage. For control purposes, the control circuit 7 can create additional magnetic flux to the magnetic flux in the magnetic circuit 1. Additional magnetic flux can be added to the existing magnetic flux and with appropriate control of this additional flux at the output of the secondary electric circuit 3, the required parameters of the extracted energy can be obtained. The control circuit 7 can take as the basis, for its execution of the control function, the voltage information from the voltage meter 10 in the secondary circuit 3 and / or on the load 8. The current meter II is used to measure the current in the secondary circuit 3. The additional magnetic flux generated by the control circuit 7 can, as mentioned above, be used to control the frequency, amplitude and / or phase, which are related to the output energy of the secondary circuit 3.

It should be noted that the control circuit 7 can receive external control commands via input 12.

In addition, the circuit 7 can be adapted for the implementation of passive control using the winding 9. Passive control means that the control does not use energy from some external source. In this regard, it should be pointed out that the control circuit 7 can combine one or more passive elements, such as resistances, capacitances or inductances, connected in series or in parallel through the control winding 9. Such passive elements connected to the winding 9 serve to exert various influences on the magnetic flux and, as a result, on the frequency, amplitude and / or phase, which relate to the energy diverted from the device.

From FIG. 1 also shows that the device, on its primary side, contains a voltage meter 13 and a current meter 14, similar to those mentioned in relation to the secondary side of the device.

FIG. 2 shows an exemplary embodiment of a transformer that differs from that shown in FIG. 1 only in that the core 6 of the magnetic circuit 1 contains an additional rod 16, in addition to the rods 15 and 17, located respectively on the secondary and primary sides of the device. This means that the core 6, as shown in FIG. 2, forms two different magnetic flux paths, schematically indicated by reference numerals 18 and 19, respectively. In this case, the control winding 9a is located around the central rod 16, i.e. around the magnetic flux path 18 that passes through the primary winding 4 of the transformer. On the contrary, the second path of the magnetic flux 19 passes around the winding 9a through the secondary winding 5 of the transformer. In this case, it becomes possible to influence through the control circuit 7 the magnetic flux in the rod 16 by means of a winding 9a, which, in turn, will affect the magnetic flux in the rod 15 through the secondary winding 5. In other words, the control winding 9a here is only related to one of two magnetic flux paths.

In accordance with the embodiment shown in FIG. 3, another control winding 9b2 has been added to the already existing winding 9b1. Both of these control windings are located around their own rods 16b, 15b, i.e. the windings 9L1 and 9L2 will be located along the tracks 18, 19 of the magnetic fluxes, respectively. The control circuit 7b comprises a control unit 20, which, in turn, acts on the control elements 21 and 22 interacting with the windings 9L1 and 9L2, respectively. By active or passive control of the elements 21, 22 through the control unit 20, such regulation can be carried out, as a result of which the magnetic flux will go along only one of the paths 18, 19 or be divided into each.

As seen in FIG. 3, the secondary winding 5b of the transformer contains at least two winding portions 23 and 24 connected in series, respectively. Through the main part 23 of the winding magnetic flux goes along the paths 18, 19, while through the part 24 of the winding magnetic flux goes along the path 19. This means that when the magnetic flux goes only through the rod 16b, due to the windings 9L1 and L2, respectively, it will not go through part 24 of the winding. This will lead to a decrease in the output voltage in comparison with the case when the magnetic flux completely goes along path 19, i.e. through both parts 23 and 24 of the secondary winding. Thus, the control winding 9b1 in this case will perform the function of complete or at least partially interrupting the magnetic flux through the rod 1 6b.

FIG. 4 illustrates an embodiment of a reactor, to some extent resembling a transformer, in accordance with FIG. 3. The difference is that the reactor has no secondary side, and instead the power winding is divided into two winding parts 25, 26. As in the previous embodiment, there are two control windings 9c1 and 9c2, by means of which the magnetic flux can thus be controlled, which, as required, will flow through the winding portion 26. Full magnetic flux will always go through winding portion 25.

FIG. 5 shows a very simplified diagram of an example implementation of a generator with a rotor 26. The rotor here is a permanent magnet. However, it is also possible to design a rotor with excitation windings. The magnetic circuit 14 here contains an electrical output circuit 54 inductively coupled to the magnetic flux in the core 64. The core 64 has areas located adjacent to the rotor 26, so that during the rotation of the rotor its permanent magnets will generate a magnetic flux in the core. This flow will go through the output winding 54, creating a corresponding effect on the output. The control circuit 74 contains, as mentioned above, a control winding 94 inductively coupled to the magnetic circuit 1 4. A voltage meter 104 and a current meter 114 are also provided for monitoring the output power output. Using the control circuit 74, the control winding 94 will passively or actively perform the function of maintaining the output from the power generator with the required frequency, amplitude and / or phase values.

It should be noted that the drawings illustrate very simplified examples of the implementation of devices, more precisely, with only one phase. In fact, such devices can be much more complicated, being, in particular, multiphase. The number of windings and parts of the windings can be much larger than shown, and this applies not only to the primary and secondary windings, but also to the control windings. In addition, magnetic circuits, depending on the functions, may have different designs.

Especially it is necessary to point out that in accordance with the invention, at least one of the existing windings contains a conductor surrounded by two equipotential layers with continuous insulation between them, which means that the electric field around the conductor will be essentially enclosed in a cable such that the primary and secondary windings can be placed anywhere on a magnetic circuit with a very high degree of freedom of such an arrangement. Perhaps even the insertion of the windings into each other. In this regard, it should be noted that the mentioned control scheme can be used for transformers of both types - with core and armored.

In particular, this winding design is suitable for high-voltage devices. Since the control windings / windings 9 are usually at a lower potential than the power windings, the control windings / windings do not need to be provided with such an insulating system as at least one of the power windings.

An important condition for the creation of an electromagnetic device, in accordance with the invention, is the use of at least one winding of an electrical cable with continuous electrical insulation with an inner semiconductor layer or sheath between the insulation and one or more conductors located inside this layer and the outer a semiconductor layer or a shell located outside the insulation. Such cables are used as standard cables in other engineering areas related to power plants, namely for energy transmission. To be able to describe an embodiment of the invention, a brief description of a standard cable will first be given. Internal conductor contains a number of conductors. The inner semiconductor layer is located around the cores. Around this semiconductor layer is a layer of solid insulation. Solid insulation is made of a polymer material characterized by low electrical losses and high resistance to breakdown. As examples of specific polymeric materials, mention may be made of polyethylene (PE) and especially network polyethylene (ХЬРЕ), as well as ethylene propylene (EP). A metallic shield and an outer insulating sheath may be provided around the outer semiconductor layer. The semiconductor layers are made of a polymer material, for example, a copolymer of ethylene with an electrically conductive component, for example, conductive carbon black or carbon black. These cables are listed below as power cables.

A preferred embodiment of a cable for winding a rotary electric machine is shown in FIG. 6. Cable 41 contains a current-carrying conductor 42 comprising grouped, uninsulated and insulated conductors. Electromechanically grouped cores with solid insulation can also be used. These conductors can be twisted / grouped into several layers. Around the conductor 42 is an internal semiconductor layer 43, which, in turn, is surrounded by a uniform layer of continuous insulating material. Isolation 44 is not liquid or gaseous type insulation. The insulation layer 44 is surrounded by the outer semiconductor layer 45. The cable used in the preferred embodiment as a winding may be provided with a metallic screen and an outer sheath, but this is undesirable. In order to eliminate induced currents and the associated losses in the outer semiconductor layer 45, this layer is divided by cutting, preferably at the end of the coil, i.e. in transitions from a sheet package to face windings. The cutting is carried out so that this layer is divided into several parts located along the cable, which are completely or partially electrically separated from each other. Each individual part of layer 45 is then grounded, making this layer throughout the entire cable at or below ground potential. This means that around the winding, insulated with solid insulation at the ends of the coils, the contact surfaces, as well as surfaces contaminated after a certain period of operation, will have very little potential with respect to the ground, which will cause very small electric fields.

To optimize the operation of a rotating electrical machine, the design of magnetic circuit elements, such as grooves and teeth, is crucial. As mentioned, the grooves should be as close as possible to the shell of the sides of the coils. It is also desirable that the teeth on each radial level be as wide as possible. This is important to minimize losses, to meet the requirements of magnetization, etc. of the machine.

When used as a conductor for winding, for example, the cable described above, there are great opportunities for optimizing the magnetic core from several points of view. The stator magnetic circuit of a rotating electric machine will be described below. FIG. 7 shows an axial end view of sector 46 with the division of the poles of the machine, in accordance with the invention. In this figure, a rotor with a rotor pole is denoted by 47. The stator, as usual, consists of a lamellar core, made up of plates or sheets made of electrical steel, which are successfully shaped into a sector. A series of teeth 49 project radially inward in the direction of the rotor from the rear portion of the core 48 located at the radially extreme end. A corresponding number of grooves 10 are located between the teeth. with famous cars. The grooves have a cross section that tapers towards the rotor, since for each layer of the winding the need for cable insulation in the direction of the rotor is reduced. As seen in FIG. 7, the groove has a substantially circular cross section 52 and is located around each winding layer with tapering portions 53 between the layers. With some qualification, this section of the groove can be called a cyclic chain groove. Since such a high-voltage machine requires the use of a relatively large number of layers, and the availability of appropriately sized cables with appropriate insulation and outer semiconductor layers is limited, in practice it can be difficult to implement the desired continuous tapered insulation and cable and stator groove, respectively. In the exemplary embodiment shown in FIG. 7, use cables of three different sizes, arranged in sections in three sections 54, 55 and 56 of the respective sizes, i.e. with practical preparation of a modified cyclic chain groove. This figure also shows that the stator teeth 49 have an almost constant radial width along the entire depth of the groove.

It should again be pointed out that the winding sections 54, 55 and 56 in FIG. 7 correspond to winding 56 in FIG. 5. Conversely, in FIG. 7, one or more windings 40 correspond to control winding 96 in FIG. 5. These control windings 40 in the illustrated embodiment are located radially outside the rotor. It should be noted that it is not necessary to arrange the winding 96 at the location of the windings 40 in FIG. 7

In accordance with an alternative embodiment, the cable used as a winding can be the standard power cable described above. Grounding of the outer semiconductor layer is carried out through the metal shield and cable jacket, opening them for this purpose in the appropriate places.

The invention covers a large number of alternative embodiments depending on the size of the cable available when it comes to isolating an outer semiconductor layer, etc. In addition, embodiments with so-called cyclic chain grooves can be modified to a greater extent than described here.

As mentioned above, the magnetic circuit may be located in the stator and / or rotor of a rotating electrical machine. However, the design of the magnetic circuit will mainly correspond to the description given above, regardless of whether it is located in the stator and / or the rotor.

Preferably, a multilayer concentric cable winding is used as the winding. Such a winding minimizes the number of intersections at the ends of the coils by placing all the coils inside one group radially outside each other. It also provides a simplified method of manufacturing the stator winding and screwing it into different slots. Since the cable used in accordance with the invention is relatively easy to bend, the winding can be obtained using the relatively simple operation of screwing the flexible cable into the holes 52 of the slots 50.

FIG. 8 shows a simplified, basic view illustrating the distribution of the electric field around the winding of a standard power transformer / reactor, where 57 is the winding, 58 is the core and 59 is equipotential, i.e. lines where the electric field has the same magnitude. It is assumed that the lower winding is grounded, that is, it is under the ground potential.

The potential distribution determines the structure of the insulation system, since it is necessary to have sufficient insulation between adjacent windings and between each winding and the ground. FIG. 8, therefore, it is shown that the insulation of the top of the winding is subjected to very high loads. The design and location of the winding relative to the core are determined, therefore, mainly by the distribution of the electric field in the window of the core.

A cable that can be used in the windings of dry transformers / reactors in accordance with the invention is described with reference to FIG. 6. As mentioned earlier, the cable may be provided with other additional outer layers for special purposes, for example, to prevent excessive electrical loads on other zones of the transformer / reactor. The area of the cable conductors is 2-3000 mm ² , and the outer diameter of the cable is 20-250 mm.

The windings of a power transformer / reactor made of the cable described in the Summary of the invention can be used for single-phase, three-phase and multi-phase transformers / reactors, regardless of the shape of the core. FIG. 9 shows an embodiment of a three-phase transformer with a lamellar core. The core contains, as usual, three rods 60, 61 and 62 and holding yokes 63 and 64. In this embodiment, the rods and yoke have a tapering cross-section along their length.

Around the core cores are concentrically arranged cable windings. As follows from FIG. 9, this embodiment has windings, each formed by three concentric coils 65, 66 and 67. The outermost coil 65 may serve as the primary winding, and the other two coils 63 and 64 of the winding as the secondary windings. In order not to overload the FIG. 9 too many parts, winding connections not shown. On the other hand, this figure shows that in certain places around the windings are intermediate rods 68 and 69, performing several different functions. These intermediate rods, which can be made of insulating material, are designed to provide a certain space between the concentric windings of the winding for their cooling, fastening, etc. These rods can also be made of electrically conductive material so as to constitute a part of the grounding system of the windings.

FIG. 9, control windings 9 are not shown.

Alternative cable designs

In the embodiment of the cable shown in FIG. 10, the same reference numerals are used as in FIG. 6, but only with the addition of the letter a. In this embodiment, the cable contains several electrical conductors 42a, separated by insulation 44a. In other words, the insulation 44a serves as insulation between the individual adjacent conductors 42a and between the latter and their surrounding elements. Different conductors 42a may be arranged in various ways in cables of different cross sections. As shown in FIG. 10, the conductors 42a are arranged in a straight line with a relatively flat cable cross section. From this we can conclude that the shape of the cable section can vary widely.

In the exemplary embodiment shown in FIG. 10, the voltage between adjacent conductors is presumably less than the phase voltage. More specifically, it is assumed that the conductors 42a are wound differently in the winding, as a result of which the voltage between adjacent conductors is relatively low.

As mentioned above, the semiconductor outer layer 45a outside the insulation 44a is formed from a solid electrical insulating material. An inner layer 43a of a semiconductor material is located around each conductor 42a, i.e. each conductor has its own inner semiconductor layer 43a surrounding it. This layer 43a will accordingly serve to equalize the potential with respect to the individual conductor.

In the embodiment of the cable shown in FIG. 11, the same reference numerals are used as in FIG. 6, but with the addition of the letter b. In this variant, several, more precisely, three conductors 42b are provided. It is assumed that there is a phase between these conductors, i.e., essentially a significantly higher voltage than between conductors 42a in the embodiment, in accordance with FIG. 10. As shown in FIG. 11, inside the inner semiconductor layer 43b there are three conductors 42b. However, each conductor 42b is surrounded by an additional own layer 70, the properties of which correspond to the properties of said inner layer 43b. Between each layer 70 and layer 43b there is an insulating material. Accordingly, the layer 43b will serve as a potential equalizing layer outside the additional layers 70 of semiconductor material, which are thus electrical conductors, and the layers 70, being connected with the corresponding electrical conductor 42b, are at the same potential as the corresponding conductor.

Possible modifications

It is obvious that the invention is not limited to the embodiments described above. It is clear to the skilled person that within the basic concept of the invention, as defined by the attached claims, a number of corresponding detailed modifications are possible. For example, the invention is not limited to the specific materials given above as examples. Instead, they can use other materials, respectively, with similar functional purposes. In the manufacture of insulation in accordance with the invention are possible other than extrusion and spraying, technological methods to ensure tight contact between the various layers. In addition, additional equipotential layers may be provided. For example, one or more equipotential layers of semiconductor material may be located between the inner and outer insulation layers mentioned above. It should be mentioned again that, in accordance with the invention, it is not necessary to form the control windings 9 by means of the flexible cable described above, because the winding or control windings are usually at a lower voltage than the other windings of the electromagnetic device. More precisely, the remaining windings are in fact high-voltage windings. Otherwise, it should be pointed out that the exact control principle in implementing the method in accordance with the invention may vary in various ways within the range of the objective control functions.

Claims (35)

1. An electromagnetic device comprising at least one magnetic circuit (1) and at least one electric circuit (2, 3) having at least one winding (4, 5), the magnetic and electric the circuit is inductively connected to each other, as well as a control circuit (7) for controlling its operation, characterized in that the control circuit (7) is configured to control the frequency, amplitude and / or phase of the electrical energy supplied to and removed from the device using the means contained therein (9) for managing magnetic flux in a magnetic circuit, and at least one winding (4, 5) or at least part of it is made of a cable having at least one electrical conductor (42) and an insulating system containing an electrical the insulation (44) formed by the continuous insulating material, the inner layer (43) is located under the insulation, and the outer layer (45) is located outside the insulation, these layers being made of semiconductor material, with at least one electrical conductor (42) located inside the inner layer (43), and the elec the conductivity of the inner layer is less than the electrical conductivity of the electrical conductor and sufficient for this layer to perform the function of equalizing the electric field outside the inner layer. 2. The device according to claim 1, characterized in that the control means comprise at least one control winding (9) inductively coupled to the magnetic circuit. 3. The device according to claim 1 or 2, characterized in that the control circuit (7) is designed to control the magnetic resistance of the magnetic circuit. 4. The device according to any one of claims 1 to 3, characterized in that the control circuit is designed to add magnetic flux to the magnetic flux of the magnetic circuit. 5. The device according to claim 3, characterized in that the magnetic circuit includes material with a magnetic permeability of more than 1, while the control circuit (7) is designed to control the magnetic resistance of the magnetic circuit by changing the magnetic permeability of one or more of these zones of the magnetic circuit, which have variable magnetic permeability. 6. The device according to claim 5, characterized in that the zone or zones with variable magnetic permeability, contain one or more gaps in the magnetic circuit. 7. Device according to any one of claims 1 to 6, characterized in that the winding (4, 5) is an air winding. 8. The device according to any one of claims 1 to 6, characterized in that the winding is wound around a magnetic core (6). 9. A device according to any one of claims 2 to 8, characterized in that the control winding (9) and the electric circuit winding (4, 5) are arranged so that substantially the same magnetic flux passes through them. 10. A device according to any one of claims 1 to 9, characterized in that it is a reactor capable of controlling by means of at least one frequency, amplitude and / or phase control winding of electric energy transferred through the winding (4,5) electrical circuit. 11. A device according to any one of claims 1 to 8 or 10, characterized in that the electrical circuit (2) contains at least two windings (23, 24) connected in series, while the magnetic circuit provides at least , two alternative paths (18, 19) of the magnetic flux, and at least one control winding is designed to control the magnetic flux so that it goes along either of these paths or both of them, and the two windings of the electric circuit are arranged in such a way that one of them can be disconnected from the magnetic flux by means indicated by at least one control winding. 12. The device according to any one of claims 1 to 9 or 11, characterized in that the magnetic circuit is located in the stator or rotor of a rotating electric machine. 13. The device according to any one of claims 1 to 9, characterized in that the magnetic circuit (1) is a magnetic circuit of a transformer having primary and secondary windings (4, 5), the primary and secondary windings, as well as the winding (9) the controls are arranged so that the same magnetic flux passes through them. 14. The device according to any one of claims 1 to 8, characterized in that the magnetic circuit is a magnetic circuit of a transformer, wherein the secondary winding of the transformer contains at least two series-connected parts of the winding, the magnetic circuit provides at least two alternative paths (18, 19) of the magnetic flux, and at least two existing control windings (9Ы, 9Ь2, 9с1, 9с2) are designed to control the magnetic flux so that it goes along one or both of these paths, with two parts of the secondary winding They arranged so that one of them may detach from the magnetic flux through the control windings. 15. The device according to any one of paragraphs. 11-14, characterized in that it comprises a magnetic core having at least three rods connected in parallel, with two different paths of magnetic flux passing through two of them, while the third rod is common to two paths of magnetic flux. 16. The device according to any one of claims 1 to 15, characterized in that the insulation system outside the insulation contains an outer layer (45), the conductivity of which is higher than that of the insulation, which makes the outer layer capable of grounding or when connected with a relatively low potential to perform the function of equalizing the potential. 17. The device according to any one of claims 1 to 16, characterized in that the outer layer (45) is located so that it essentially encloses within itself an electric field created by the specified electric conductor (42). 18. Device according to any one of claims 1 to 17, characterized in that the inner layer (43) and continuous insulation have essentially similar thermal properties. 19. Device according to any one of claims 1 to 18, characterized in that the outer layer (45) and continuous insulation have essentially similar thermal properties. 20. The device according to any one of claims 1 to 19, characterized in that at least one cable forms at least one inductive coil. 21. The device according to any one of claims 1 to 20, characterized in that the inner layer (43) and / or the outer layer (45) have a resistivity in the range of 10 ^-6 Ohm-cm -100 kOhm-cm, suitable 10 ^-3 -1000 ohm-cm, preferred 1-500 ohm-cm. 22. The device according to any one of claims 1 to 21, characterized in that the inner layer (43) and / or the outer layer (45) have a resistance that is 50 μOhm - 5 MΩ per 1 meter of the length of the conductor / insulation system. 23. Device according to any one of claims 1 to 22, characterized in that the continuous insulation (44), the inner layer (43) and / or the outer layer (45) are made of polymeric materials. 24. Device according to any one of claims 1 to 23, characterized in that the inner layer (43) and / or the outer layer (45) and the continuous insulation (44) are rigidly connected to each other, essentially over the entire interface to provide also the adhesion between them when bending and changing temperature. 25. The device according to any one of claims 1 to 24, characterized in that the continuous insulation, internal The 1/6 layer and / or the outer layer are made of materials having high elasticity, contributing to their mutual adhesion during deformation during operation. 26. The device according to any one of claims 1 to 25, characterized in that the continuous insulation, the inner layer and / or the outer layer are made of materials having essentially the same elastic modules (E - modules). 27. Device according to any one of claims 1 to 26, characterized in that the inner layer (43) and / or the outer layer (45) and continuous insulation (44) are made of materials having essentially the same coefficients of thermal expansion. 28. The device according to any one of claims 1 to 27, characterized in that the conductor (42) and its insulation system comprise a winding formed by a flexible cable (41). 29. Device according to any one of claims 1 to 28, characterized in that the inner layer (43) is in electrical contact with at least one electrical conductor (42). 30. The device according to clause 29, wherein the at least one electrical conductor (42) contains a number of cores, and at least one core of the electrical conductor (42) is at least partially insulated and is in electrical contact with the inner layer (43). 31. The device according to any one of claims 1 to 30, characterized in that the conductor (42) and its insulation system are designed for high voltage above 10 kV, in particular above 36 kV and, preferably, above 72.5 kV. 32. The device according to p. 12, characterized in that the magnetic circuit contains one or more magnetic core (48) with grooves (50) for winding (41). 33. The device according to any one of paragraphs.12 or 31-32, characterized in that it is a generator, motor or synchronous compensator. 34. The device according to any one of paragraphs.12 or 32-33, characterized in that it is directly without an intermediate transformer connected to a power grid operating under high voltage, of the order of 36 kV or more. 35. The device according to any one of paragraphs.11 or 13-31, characterized in that it is a power transformer or reactor.