CZ20001906A3 - Electromagnetic device - Google Patents

Abstract

The electromagnetic device consists of at least one magnetic circuit (1) and at least one electric circuit a circuit (2, 3) formed by at least one winding (4, 5). Magnetic and electrical circuits are mutually inductive connected. The apparatus further comprises a control arrangement (7) k control the operation of this device. The control arrangement (7) is adapted to control frequency, amplitude and / or phase related electrical power to or from this device by this control arrangement (7) including the control means (9) for controlling the magnetic flux in the magnetic circuit (1).

Description

Electromagnetic equipment

Technical field

The invention relates to an electromagnetic device comprising at least one magnetic circuit and at least one electrical circuit with at least one winding, wherein the magnetic and electrical circuits are inductively coupled to each other, and the device further comprises a control arrangement for controlling the operation of the device.

This electromagnetic device can be used in any electrical connection. The power can range from VA up to 1000 MVA. In particular, it is intended for use with high voltages up to the highest simultaneously transmitted voltage.

According to a first aspect of the invention, it is envisaged for use in rotary electrical machines. Such electrical machines include synchronous machines which are mainly used as generators for connection to distribution and transmission networks, hereinafter commonly referred to as power networks. Synchronous machines are also used as motors and for phase shift compensation and voltage control in the case of mechanically unloaded machines. The field of technology also includes dual-power machines, asynchronous cascade converters, external pole machines, synchronous induction machines, and asynchronous machines.

According to a second aspect of the invention, the electromagnetic device comprises a power transformer or a reactor. Transformers are used for all types of electricity transmission and distribution, and are designed to facilitate the exchange of electricity between two or more electrical systems, using a well known way for this task ··· ·

- 2 electromagnetic induction. The transformers, particularly contemplated according to the present invention, are so-called power transformers having a rated power of several hundred kVA up to more than 1000 MVA, with a rated voltage of 3 to 4 kV to very high transmission voltages of 400 kV to 800 kV or higher.

Although the following description of the prior art with respect to the first aspect mainly relates to power transformers, the present invention is also applicable to reactors, both single-phase and three-phase reactors. As far as insulation and cooling are concerned, there are essentially the same designs as transformers. Thus, air and oil insulated reactors, self-cooled or pressurized oil cooled, etc. are available. Although the reactors have a single winding (per phase) and can be constructed with or without a magnetic core, the description of the state of the art also extends to reactors.

BACKGROUND OF THE INVENTION

The at least one winding of the electrical circuit may be loosely wound in some embodiments, but typically comprises a magnetic core of laminated normal or oriented layer or other, for example, amorphous or powdered material, or may include any other function to allow alternating magnetic flux, and winding . The circuit often includes some kind of cooling system, etc. In the case of a rotating electric machine, the winding may be located in the stator or rotor of that machine or in both the stator and rotor. '

A problem of known embodiments of electromagnetic devices

The three types described above are either that it is relatively difficult to achieve efficient control over a range of parameters here, or that the control arrangement is usually relatively expensive. In this context, it should be pointed out that it is known in the art of generators to control operating parameters by means of an excitation winding. If the rotor comprises electromagnets, this excitation coil is arranged on the rotor, which has the disadvantages that this embodiment is more expensive and more difficult to control. In the case of a permanent magnet rotor, there is a problem that control of the electromagnetic field is practically impossible. This, of course, poses a lot of difficulty in carrying out the procedure generally, and especially in the special cases of fine steering. Another problem associated with the prior art is that conventional winding techniques for obtaining windings are expensive. The known embodiments also cause substantial energy losses and include restrictions on the location of the winding in the magnetic circuit.

SUMMARY OF THE INVENTION

It is an object of the present invention to find methods for simplifying and improving the control operation of electromagnetic devices according to the preamble of the appended claim 1, and it is also an object of the present invention to create better conditions for rational production and assembly of windings.

The basic object of the present invention is achieved by modifying a control arrangement for controlling frequency, amplitude and / or phase, with respect to electrical power to or from the device by a control arrangement, comprising means for controlling the magnetic flux in the magnetic circuit.

The invention is therefore based on the idea of direct influence, 9

- 4 • 99 • 9 99 • - «9 9

9 9 · by controlling the flux, the magnetic flux in the magnetic circuit in the required respect, so that the operation of the device can be controlled. This creates a very rational and cost-effective design and, moreover, an increased control capability for. achieving optimized operation.

According to a particularly preferred embodiment of the invention, the control means comprises at least one control winding inductively connected to the magnetic circuit. The control arrangement is therefore able, by means of the control winding, to efficiently control the desired magnetic flux in the magnetic circuit by applying, by means of the control winding, control parameters such that the magnetic flux in the magnetic circuit is affected to the desired extent. The control winding could even be short-circuited. The magnetic flux would then not have to pass through the control winding in certain embodiments. Depending on the design of the magnetic circuit, partial or complete blocking of the magnetic flux may occur.

Examples of control functions that can be achieved by the present invention are voltage change and voltage stabilization, transient elimination, power line vibration damping, harmonic tone filtering, frequency adjustment and phase adjustment (in the case of separate phase control). It should be emphasized that the control arrangement according to the invention can be adapted to add an additional magnetic flux to the magnetic flux in the magnetic circuit, i.e. the control arrangement could operate with direct power supply.

The control of the magnetic flux in a magnetic circuit, for example a transformer, according to the invention means that good control can be performed by the secondary winding voltage so that it meets the specified requirements, despite the unpleasant variation in the primary voltage or load connected to the secondary winding.

9 •• 99 99

Further details and advantages of flux control in the magnetic circuit according to the invention will be apparent from the following detailed description.

It is within the scope of the invention that at least one of the windings of the electromagnetic device or at least a part of the winding comprises at least one flexible electrical conductor having a sheath which is magnetically permeable but is capable of substantially closing the electric field occurring around the conductor. In other words, this means that the flexible electrical conductor and its sheath (forming the insulating assembly) are formed by a flexible cable. This includes substantial manufacturing and assembly advantages compared to rigid windings in the prefabricated shape that have been conventional so far. The insulation system according to the invention also results in the absence of gaseous or liquid insulating materials.

Since the electric field occurring around the electrical conductor is substantially closed by the insulating system, the invention reduces the occurrence of losses so that the device can therefore operate at a higher degree of efficiency. Furthermore, the loss reduction results in a lower temperature of the device, which reduces the need for cooling and allows optional cooling devices to be constructed more easily than without this aspect of the invention.

With respect to an aspect of the invention, as a rotary electrical machine, it is thus possible to operate the machine at a voltage so high that conventional step-up transformers can be omitted. This means that the machine can be operated at a significantly higher voltage than that of the prior art machines, with the possibility of making a direct connection to the power grid. This means significantly lower investment costs for a rotary electric machine system and the possibility of increasing overall system efficiency. The present invention eliminates the need for special precautions

Of semiconductor material, a field throughout the field control device in certain winding areas, such field control measures being a necessity in the prior art. A further advantage is that the invention facilitates the achievement of under-magnetization or over-magnetization for the purpose of reducing the reactive effects due to voltage and current that are out of phase with each other.

With respect to an aspect of the invention, such as a power transformer or reactor, the present invention primarily eliminates the need for an oil-filled power transformer, and the problems and drawbacks associated therewith.

Thus, the winding construction comprises, at least in part of its length, an insulation formed from a solid insulating material, wherein the inner layer is inwardly of the insulation and the outer layer is outwardly of the insulation, whereby these layers are made to allow the electrical winding to be closed. As used herein, the term "rigid insulating material" means that the winding is devoid of liquid or gaseous insulation, such as oil. Instead, it is contemplated that the insulation will be formed from a polymeric material. The inner and outer layers are formed of a polymeric material, namely a semiconductor material.

The inner layer and the rigid insulation are rigidly connected to each other substantially over the entire interface. Also, the outer layer and the rigid insulation are rigidly connected to each other substantially over the entire interface. The inner layer controls the voltage-related equalization and thus the electric field equalization outwardly from the inner layer as a result of its semiconductor properties. It is also contemplated that the outer layer is also made of a semiconductor material, and has at least a higher electrical conductivity than the insulating properties, causing the outer layer, when grounded, or otherwise, to have a relatively low voltage for the αvvv related actions. ,

- Ί ·· ···· «· 9 9 999

9

9

9999 99 99 999 to equalize the voltage and to substantially close the resulting electric field induced by said electrical conductor inwardly from the outer layer. On the other hand, the outer layer should have a resistivity sufficient to minimize electrical losses in the outer layer.

The rigid connection between the insulating material and the inner and outer semiconductor layers should be uniform over substantially the entire interface to avoid any voids, pores or the like. With the expected high voltage level according to the invention, the electrical and thermal loads that may occur will impose extreme requirements on the insulating material. It is known that so-called partial PD discharges usually create serious problems for insulating material in high voltage installations. If cavities, pores or the like occur, internal corona discharges may occur at high electrical voltages, whereby the insulating material gradually degrades and could result in electrical puncture of the insulation. This can lead to serious failure of the electromagnetic equipment. Therefore, the insulation must be homogeneous.

The inner layer inwardly of the insulation should have an electrical conductivity which is lower than the conductivity of the electrical conductor, but should be sufficient to allow the inner layer to perform voltage compensation and thus to perform the electric field compensation outside the inner layer. This, combined with the rigid connection of the inner layer and the electrical insulation over substantially the entire interface, i.e. without cavities, etc., means a uniform electric field outside of the inner layer and minimal risk of partial discharges - PD.

It is preferred that the inner layer and the solid electrical insulation are formed of materials having substantially the same coefficients of thermal expansion. The same is advantageous when it comes to φ ft ft ft ft ft ft ft ft ft ft φ ft ft ft ft ft φ φ φ ft ft ft ft φ φ · ··

- 8 ο outer layer and solid insulation. That is, the inner and outer layers and the rigid electrical insulation form an insulating system that expands and contracts uniformly as a monolithic portion, depending on temperature variations, without allowing for any damage or distribution at their interface. Thus, perfect surface contact between the inner and outer layers and the rigid insulation is provided, and conditions are created to maintain this perfect contact during the extended operating time. Such coherence should be such as to ensure coherence between at least the inner layer and the rigid insulation, and in particular also between the outer layer and the rigid insulation, in connection with the bending to which the electrical conductor and the insulation system will be subjected. It should be emphasized that said cable, in order to be wound into a winding, should be resilient or flexible in a radius of curvature of less than 25 times the cable diameter, preferably less than 15 times the cable diameter. In a most preferred embodiment, the cable is flexible in a radius of curvature that is less than or substantially equal to 8 times the cable diameter.

It is important that the insulation system consists of materials having good flexibility. The modulus of elasticity of these materials should be relatively low, i.e., have a relatively low resistance to material deformation. In order to avoid hazardous shear stresses occurring in the marginal region between the different layers contained in the insulation system, it is preferred that the elasticity (modulus of elasticity - E) of these layers contained in the insulation system be substantially the same.

The electrical load of this insulation system decreases as a result of the fact that the inner and outer layers of semiconductor material around the insulation will tend to create substantially equipotential surfaces, and in this way the electric field will be · ·· ..

• * · · ♦ »9 9 · 9 • 9 9 9 9 9 9 9 9 ·

9 9 9 9 9 9 9 9 • • 99 99 99 999 99 99

- 9 distributed evenly over the insulation thickness in the actual insulation. In connection with the transmission cables for high voltage and for the transmission of electrical energy, it is known per se to construct conductors with insulation from a solid insulating material, with an inner and an outer layer of semiconductor material. The transmission of electricity has long ago achieved that the insulation should be undamaged. However, in high-voltage transmission cables, the electrical voltage does not change along the length of the cable, but the voltage is essentially at the same level. However, even with high voltage transmission cables, there may be immediate voltage differences due to transient phenomena such as lighting. According to the invention and the appended claims, flexible cables such as windings are used in this electromagnetic device.

An additional improvement can be achieved by constructing an electrical conductor in a winding of smaller so-called strands, at least some of which are insulated from each other. By providing these strands of relatively small cross-sections, preferably approximately circular, the magnetic field across these strands will exhibit a constant geometry relative to this field, while minimizing the occurrence of eddy currents.

According to the invention, the winding is therefore preferably manufactured as a cable comprising an electrical conductor and an insulating system as described above, wherein its inner layer passes around the conductor strands. Outside of this inner semiconductor layer, the main cable insulation is formed by a solid insulating material.

The outer semiconductor layer of the present invention will exhibit electrical properties to provide voltage equalization along the conductor. However, the outer layer may not exhibit conductive properties such that the induced flow will flow over the surface, which could cause losses, which in turn could create undesirable

9999 • »«

9 99 9

9 9 ·· 99

9 99 999 thermal load. For the inner and outer layers, the resistance data (at 20 ° C) as defined in the appended claims 22 and 23 is valid. As regards the inner semiconductor layer, it must have sufficient electrical conductivity to provide voltage equalization for the electric field, at the same time the resistivity to ensure the closing of the electric field.

It is important that the inner layer compensates for irregularities in the conductor surface and creates an equipotential surface with high surface quality at the interface with the solid insulation. The inner layer may be of varying thickness, but must provide a flat surface with respect to the conductor and solid insulation, where a suitable thickness is between 0.5 and 1 mm.

Such a flexible winding cable used in the electromagnetic device according to the invention is an improvement of the XLPE (cross-linked polyethylene) cable or EP (ethylene-propylene) and rubber insulated cable. This improvement includes, inter alia, a new design, both in terms of conductor strands and cable, at least in some embodiments having no outer sheath for mechanical cable protection. However, according to the invention, it is possible to provide a conductive metal housing and an outer sheath outside of the outer semiconductor layer. The metal cover will then have the role of external mechanical and electrical protection, for example against illumination. It is preferred that the inner semiconductor layer has contact with the voltage of the electrical conductor. To this end, the at least one strand of electrical conductor will be uninsulated and arranged to achieve good electrical contact with the inner semiconductor layer. Alternatively, the different strands may be alternately brought into electrical contact with the inner semiconductor layer.

Manufacturing the windings of transformers or reactors from cables, as mentioned above, requires significant differences in the distribution of electric field between conventional power

99 · I 9

9

9 9 9

99

- 11 ·· ·

9.9 9

9

9 9

9 9

9999 8 9

9999

Transformers or reactors and power transformers or reactors according to the invention. A decisive advantage in the winding made of cables according to the invention is that the electric field is enclosed in the winding and that there is therefore no electric field outside of the outer semiconductor layer. The electrical field reached by the conductor through which current flows occurs only in the fixed main insulation. This has considerable advantages in terms of both construction and production.

transformer windings can be formed without considering any distribution of the electric field, and displacement of the strands mentioned in the prior art is avoided;

a transformer core structure can be formed without considering any electric field distribution;

no oil is required for the electrical insulation of the windings, so that the medium surrounding the winding may be air;

no special connections are required for the electrical connection between the external connections of the transformer and the immediately connected coils or windings, since the electrical connection, unlike conventional devices, is integrated into the windings;

The manufacturing and testing technology required for the power transformer of the invention is significantly simpler than conventional power transformers or reactors, as the impregnation, drying and vacuum treatment described in the prior art is not required.

By using the invention as a rotating electrical machine, a substantially reduced stator thermal load is achieved.

Thus, temporary machine overloads will be less critical, and the machine will be able to steer overload for longer periods of time without risk of damage. This means significant benefits for power plant owners who are forced to switch quickly to other facilities in the event of operational disruptions,

• · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · To meet the requirements of the energy supply, according to law.

With the rotary electrical machine of the invention, maintenance costs can be greatly reduced, since transformers and circuit breakers may not be included in the machine connection system.

As already described above, the outer semiconductor layer of the cable winding is intended to be connected to zero electrical potential (ground). The purpose of this is that this layer should be maintained at substantially zero potential along the length of the cable winding. It is possible to divide the outer semiconductor layer by cutting it into several parts distributed along the length of the cable winding, each individually. the part is connectable directly to zero potential. In this way, better uniformity is achieved along the length of the cable winding.

As mentioned above, a solid insulation and inner and outer layers can be achieved, for example by extrusion. However, other techniques, such as forming the inner and outer layers and the insulation, respectively, by spraying the respective material onto the conductor or the winding are also well possible.

It is preferred that the cable winding be of circular cross-section. However, other cross-sections may also be used if desired to achieve better assembly density.

In order to start the voltage in the rotary electric machine, the cable is arranged in the grooves of the magnetic core in several successive turns. The winding may be in the form of a multi-layer concentric cable winding to reduce the number of crosses on the coil face. The cable may be made with beveled insulation to better utilize the magnetic core, in which case the shape of the grooves may be adapted to the beveled winding insulation.

A significant advantage of the rotary electric machines according to the invention is that the electric field approaches zero in the region of the face

· ♦ · · · · · · · · · · · · · · · · ·

coil, outside of the outer semiconductor layer, and that with a zero-potential outer sheath, the electric field need not be controlled. This means that no concentration of electric field can occur, either within the layers, in the regions of the coil face or in the transition between them.

In the method of manufacturing the device according to the invention, a flexible cable is used as the winding, which is wound into open grooves in the magnetic core of a rotating electric machine. Since the cable is flexible, it can bend and this allows the cable length to be laid in several turns on the coil. The ends of the spool will then consist of cable bend areas. The cable can also be connected in such a way that its properties remain constant over its entire length. This method requires considerable simplification compared to the prior art. The so-called Roebel bars are not flexible, but must be preformed to the desired shape. Winding insulation and coil impregnation is also an extremely complicated and costly method for producing rotary electrical machines today.

Thus, to summarize, an electromagnetic device, such as a rotary electric machine according to the invention, provides very many important advantages over the prior art machines. In particular, the machine according to the invention can be directly connected to the power grid of all types of high voltage. Another important advantage is that the zero potential is consistently guided along at least part of the winding, and preferably along the entire winding, which means that the coil end region can be made compact, and that the spacing means in the coil end region can be used practically at zero. potential. Yet another important advantage is that the oil insulation and cooling system also disappears in rotary electrical machines, as already pointed out above in terms of power transformers.

9 9

9 9

9 · · • · · · · • • • • • •

9

9999 ♦ · • 9 9 9 9 9 or reactors. This means that no sealing problems can arise and that the aforementioned dielectric ring is not required. It is also important that all artificial cooling can be performed with zero potential.

Overview of the drawings

The invention will be explained in more detail with reference to the accompanying drawing, in which Fig. 1 schematically shows a device according to the invention, as a transformer, Fig. 2 schematically shows a variant of a transformer, Fig. 3 schematically shows another variant of a transformer, Fig. 4 similar to FIG. 3 but with respect to the reactor, FIG. 5 is a schematic representation of one embodiment of the generator; FIG. 6 is a partial cross-sectional view of parts contained in a conventional modified standard cable; FIG. 8 shows the distribution of the electric field around the windings of a conventional power transformer or reactor; FIG. 9 shows a perspective view of one embodiment of a power transformer according to the invention; FIG. the cross section of the upra cable is shown 1 and containing several electrical conductors, and FIG. 11 is a cross-sectional view of another cable structure comprising several electrical conductors, but in a different configuration from FIG. 10.

- 15 99 9999

9 • 9,

9

9 9

999 9 9 · ·· 9999 • · 9

9

9 9

9 9

999

99

9 9 ·

9. 9 9 9

9 9 9

99

DETAILED DESCRIPTION OF THE INVENTION

The electromagnetic device shown in Fig. 1 is a transformer. It consists of a magnetic circuit 6 and two electrical circuits 2 and 3, each of which is formed by at least one coil-shaped winding 4 and 3 respectively. 5.

In this embodiment, it is shown that the transformer comprises a core 6 of magnetic material. Suitably, the core 6 consists of a set of magnetic layers to reduce eddy current losses. It should be emphasized, however, that the presence of a core is not absolutely necessary to practice the invention. Freely wound embodiments are also well within the scope of the invention. It follows that the term magnetic circuit must be interpreted in a broad sense. Therefore, this expression only means that the magnetic field generated by the winding 4, 5 could generate a magnetic flux.

The apparatus according to the invention comprises a control arrangement, generally indicated with reference numeral 7, for controlling the operation of the transformer. This control arrangement is adapted to control the frequency, amplitude and / or phase related to the electrical power output from the transformer. In this embodiment, the electrical circuit 2 forms the primary side of the transformer, while the electrical circuit 3 forms the secondary side of the transformer. The power from this device is therefore output by means of a secondary circuit 3 to which a load is connected, schematically represented by the reference numeral <8. This load may be of any nature, such as the consumer, but may also be distribution and transmission networks.

The control arrangement 7 comprises control means 9 for controlling the magnetic flux in the magnetic circuit 1. The control arrangement 7 comprises: a.

The means 9 comprises, for example, at least one control winding inductively connected to the magnetic circuit 2- In this embodiment, the control winding is wound around a portion of the core 6. In a transformer-free core design, the control winding 9 must be coordinated with the primary and secondary windings . 5, so that the magnetic flux induced in the core-free magnetic circuit is inductively connected to the control winding 2 ·

The control arrangement 7 is according to a preferred embodiment of the invention conceived as an active type, i.e. the control arrangement 7 should be adapted to be actively controlled by the control winding 9 in order to obtain the desired magnetic flux in the magnetic circuit 1. It is then preferred that the control arrangement 2 comprises an external power source so that the control arrangement 7 can control the magnetic flux passing through the magnetic circuit 1, causing the current to pass through the control winding 9. The invention is particularly advantageous in connection with the use of high voltage. This means that a comparatively high voltage is normally intended to be connected to electrical circuits and 3. In such a case, however, it is sufficient for control purposes that the control arrangement 7 cause a relatively large current to pass to the control winding 9 with a relatively high voltage. The control arrangement 7 may be adapted, for control purposes, to add an additional magnetic flux to the magnetic flux in the magnetic circuit 2. This additional magnetic flux will thus be added to the existing magnetic flux, and by appropriate control of the addition of this flux the desired parameters can be achieved. The control arrangement 7 may be adapted to obtain, as a basis for its control operation, information on the voltage from the voltage measuring device 10 relative to the voltage in the secondary circuit 3 and / or in the load 8i. to measure current

φ φ • • • • • • · ·

The addition of the flow generated by the control arrangement 7, as previously mentioned, can be used to control the frequency, amplitude and / or phase related to the electrical power output through the secondary circuit 3.

It should be emphasized that the control arrangement 7 can be adapted to obtain external control instructions by input

It should further be pointed out that the control arrangement 7 can be adapted to effect passive control by the control winding 9. Passive control means in this respect that it does not use energy from an external source for control. In this context, it should be pointed out that the control arrangement 7 may be able to connect one or more passive elements, such as resistors, capacitors or inductors, connected in series or in parallel, via the control winding 9. Such passive elements connected to the control winding 9 in a manner adapted for this purpose therefore make it possible to exert various effects on the magnetic flux, and these effects then manifest themselves in frequency, amplitude and / or phase related to the electrical power output from the device.

It can also be seen from FIG. 1 that the device on its primary side comprises a voltage measuring device 13 and a current measuring device 14, similar to those on the secondary side.

Fig. 2 shows an embodiment of a transformer that differs from the embodiment just described in Fig. 1 only in that the magnetic circuit 1 here comprises a core 6 comprising an additional arm 16, in addition to the arm 15 occurring on the secondary side of the embodiment of Figs. 1, and further comprises an arm 17 on the primary side. That is, the core 6 of FIG. 2 will be 99. 9 9

9 9

999

99

9 9 9

9 9 9

9 9 9

9 9 · ·· 99 create two different magnetic flux paths, schematically represented by broken line 18 and 9, respectively. 19. The control winding 9a is arranged in this case around the central arm 16, i.e. in the first magnetic flux path 18 passing through the primary winding 4 of the transformer. The second magnetic flux path 19, in turn, passes the control winding 9a through the secondary winding 5. By means of the control arrangement 7, it is now possible to influence the magnetic flux in the center arm 16 by the control winding 9a which in turn affects the magnetic flux in the arm 15 by the secondary winding 5 . In other words, the control winding 9a is here only connected to one or two magnetic flux paths.

The variant in Fig. 3 shows the addition of another control winding 9b2 to an existing winding 9b1. The two control windings are arranged around their own arms 16b and 15b, i.e. the control windings 9b1 and 9b2 will belong to their own magnetic flux paths 18 and 19. The control arrangement 7b comprises a control unit 20, which further controls the control elements 21 and 22, respectively. 22, coordinated with the control windings 9b1 and 22b, respectively. 9b2. By actively or passively controlling the control elements 21 and 22, via the control unit 20, an adjustment can be made so that the magnetic flux passes through either or is divided into only one of the magnetic flux paths 18 and 19.

Referring to FIG. 3, it should also be noted that the transformer secondary winding 4b comprises at least two portions 23 and 22, respectively. 24 windings connected in series. The magnetic flux in both the magnetic flux paths 18 and 19 passes through the main winding portion 23, while only the magnetic flux in the path 19 passes through the winding portion 24. That is, when the magnetic flux passes only through the arm 16b via the control winding 9b1 and 9b2, no magnetic flux passes through the winding portions 24. This means lower • · ·

Output voltage than the voltage applicable to the case in which the magnetic flux passes entirely through the magnetic flux path 19 than when the total magnetic flux passes through both the part 23 and the part 24 of the secondary winding. Thus, the control winding 9b 1 in this operating case is intended to completely or at least partially interrupt the magnetic flux in the arm 16b.

FIG. 4 shows an embodiment of the reactor somewhat resembling the transformer of FIG. 3. The difference is that the reactor has no secondary part, so that instead its 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 be controlled to pass to the desired degree in the winding portions 26. The total magnetic flux always passes through the winding portion 25. '

FIG. 5 shows a very simplified embodiment of a generator whose rotor is designated 26. This rotor 26 is designed as a permanent magnet rotor in an exemplary embodiment. However, it would also be possible to design a rotor with an excitation coil. The magnetic circuit 1d here comprises an electrical output winding 5d inductively coupled to the magnetic flux in the core 6d. The core 6d has portions positioned close to the rotor 26 so that the permanent magnets generate a magnetic flux in the core as the rotor 26 rotates. The magnetic flux passes through the output winding 5d and generates an output effect therein. The control arrangement 7d comprises, as before, the control winding 9d inductively coupled to the magnetic circuit 1d. There is also a measuring device 10d, resp. people to measure voltage, respectively. to control the output power. By means of the control arrangement 7d, the control winding 9d can now be brought into the functional state required for a passive or active control purpose to transmit the desired output power characteristics from the generator if: 9

99 9900 99

9 · 9 9

999 · 9

9 9 9 9 9

999 99 99

- 20 refers to frequency, amplitude and / or phase.

It should be pointed out that the figures show very simplified embodiments, in particular with only one phase. In fact, these embodiments can be much more complex, especially as multiphase embodiments. The number of windings and winding parts can be much higher than described, not only in terms of primary and secondary windings, but also in terms of the number of control windings. Also, the magnetic circuits may have a variable configuration, depending on the functional requirements.

In particular, it should be pointed out that the fact that according to the invention at least one of the existing windings comprises an electrical conductor surrounded by two mutually separated equipotential layers and a solid insulation located between these layers means that the electric field around the conductor will be substantially enclosed in the cable. . so that the primary and secondary windings can be located anywhere in the magnetic circuit with very great freedom. Even winding insertion is possible. In this context, it should be emphasized that the control arrangement is suitable for transformers of both types, both core and shell transformers.

The construction just described is particularly suitable for high voltage applications. It should be pointed out that the control winding resp. the control winding 9 will have a lower voltage than the power winding, because the control winding need not necessarily be provided with such an insulation system as at least one of the power windings.

An important aspect for the possibility of forming an electromagnetic device according to the invention is to use for at least one winding the use of a solid conductor insulated cable conductor with an inner semiconductor layer or sheath between the insulation and one or more electrical conductors disposed inside the insulation. . Such cables are available as

- 21 ······························

9 9 9 · 9 · 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9

9 9 Standard cables for use in other areas of power engineering, namely in power transmission. In order to describe an embodiment, a standard cable will first be briefly described. The internal conductor through which the current flows contains a number of strands. Around these strands is a semiconductor inner layer or sheath. Around this semiconductor inner layer is an insulating layer of solid insulation. The rigid insulation is made of a polymeric material with low electrical losses and high breakdown strength. Specific examples are polyethylene (PE), and in particular cross-linked polyethylene (XLPE) and ethylene-propylene (EP). A metal housing and an outer insulating sheath may be provided around the outer semiconductor layer. The semiconductor layers consist of a polymeric material, such as an ethylene copolymer, with an electrically conductive component, such as conductive carbon black or carbon black. Such a cable will be referred to herein as a power cable.

A preferred embodiment of a winding cable in rotary electrical machines is shown in FIG. 6. The cable 41 shown in FIG. 6 comprises a current conductor 42 that includes both transposed, non-insulated and insulated strands. . Electromechanically transposed, rigidly insulated strands are also possible. These strands can be entangled or transposed in a number of layers. Around this conductor 42 is an inner semiconductor layer 43, which in turn is surrounded by a homogeneous insulating layer 44 of rigid insulating material. This insulating layer 44 is completely free of liquid or gaseous insulating material. This insulating layer 44 is surrounded by an outer semiconductor layer 45. The cable used as winding in a preferred embodiment of the invention may be provided with a metal cover and an outer cover, but need not be provided with such a cover. For prevention

- 22 Induced currents and losses associated with them, in the outer semiconductor layer 45, is this layer This cut is done so that the outer semiconductor layer 45 is divided into several parts distributed around the cable, which are electrically completely or partially separated from each other. the portion is then connected to ground, whereby the outer semiconductor layer 45 is maintained at or near zero potential along the entire length of the cable.This means that around the tightly insulated winding on the coil ends, they have surfaces that can come into contact with each other and polluted after some time of use, only negligible potential, and can also cause negligible electric fields.

In order to optimize rotating electrical machines, the design of the magnetic circuit in terms of grooves and / or grooves is crucial. of teeth. As mentioned above, the grooves should be connected as tightly as possible to the coil side housing. It is also desirable that the teeth in each radial plane be as wide as possible. This is important to minimize losses, magnetization requirements, etc. machines.

With access to a winding conductor, such as the cable described above, there are great possibilities to optimize the magnetic core from various points of view. The following is a description of the magnetic circuit of the stator of a rotating electric machine. FIG. 7 shows an axial front view of one embodiment of a sector or pole pitch 46 of a machine according to the invention. The rotor pole rotor is designated 47. The stator usually consists of a laminated core of electrical layers, successively composed of sector-shaped layers. A row of teeth 49 extends from the rear portion 48 of the core, located radially at its extreme outer end.

- 22 9 9 9

9 ·

9 · ·· • · • 9 9 9 9 ♦ ·

9 9 9 radially inwardly toward the rotor 47. Among these teeth 49 there is a corresponding number of grooves 50. The use of the cables 51 according to the above-described embodiment allows, inter alia, that the depth of the grooves for high voltage machines is greater than possible . The grooves 50 have a cross-section beveled toward the rotor 47, since the need for cable insulation becomes less for each winding layer towards the rotor. As can be seen from this figure, the groove 50 consists of a circular cross section 52, around each winding layer, with narrower strip portions 53 between the layers. With some authority, such a groove cross-section may be referred to as a "cyclic groove chain." Since such high voltage machines will require a relatively large number of layers, and the availability of cables with appropriate dimensions and insulation, and outer semiconductor layers is limited, it may be difficult in practice to achieve the desired continuous bevel of cable insulation or stator grooves. In the embodiment shown in FIG. 7, cables with three different dimensions of cable insulation are used, arranged in three respectively sized sections 54, 55 and 56, i.e. in practice a modified cyclic groove chain is obtained. Also shown in this figure is that the stator tooth 49 can be formed with practically constant radial width along the depth of the entire groove.

Again, it should be noted that the winding sections indicated by the reference numerals 54, 55 and 56 in FIG. 7 correspond to the winding 5d in FIG. 5. On the other hand, one or more windings corresponding to the control winding 9 in FIG. These control windings 40 are in this embodiment positioned radially as far as possible outside the rotor 47. It should be pointed out that it is not necessary to position the control winding 2 at the locations indicated by the reference numeral 40 in Fig. 7.

- 24 • 9 · 9 · 9 9 9 9999 99 99

9 '9 9 · 9 9 * 99

9 9999 9 99 9

999 9,999 9 9 9

9 9 99

9999 9 9 9 · 999 99

In an alternative embodiment, the cable used as the winding may be a conventional power cable as described above. The outer semiconductor layer 45 is then grounded by peeling off the metal cover and the cable sheath at suitable locations.

The scope of the invention is adapted to a large number of alternative embodiments, depending on the available cable dimensions with respect to the insulating and outer semiconductor layers, etc. Also, embodiments with a so-called cyclic groove chain may be modified, beyond what has been described herein.

As mentioned above, the magnetic circuit may be located in a stator and / or rotor of a rotating electric machine. However, the embodiment of the magnetic circuit will broadly correspond to the embodiment described above, regardless of whether the magnetic circuit is located in the stator and / or rotor.

In particular, windings are used as windings, which may be referred to as multi-layer concentric cable windings. That is, in such a winding, the number of crossings on the ends of the coil has been minimized by placing all coils radially outwardly within the same group. This also allows a simpler method of manufacturing and winding the stator windings into different grooves. Since the cable used according to the invention is relatively easily flexible, this winding can be achieved by a relatively simple winding operation in which the flexible cable is wound into an open circular cross-section 52 in the grooves 50.

Fig. 8 shows in a simplified and basic manner the distribution of the electric field around the windings of a conventional power transformer or reactor, with the representation of the windings 57, core 58 and equipotential lines 59, i.e. lines where the electric field is the same size. The lower part of the winding is considered to have zero potential.

The potential distribution (voltage) determines the insulation composition

- 25 ·· ···· · · · · ♦ · * · · · · · φ · φ · φ φφφφφφφφφφφ ·φφφφφφφφφφφφφφφφφφφ soustavy aby aby aby aby aby aby there was sufficient insulation, both between the windings and between each winding and ground. Thus, this figure shows that the upper part of the winding is exposed to the highest insulation load. The design and positioning of the windings relative to the core is thus determined essentially by the distribution of the electric field in the core window.

The cable which can be used for winding in dry power transformers or reactors according to the invention has been described with reference to FIG. other locations of the transformer or reactor. In terms of geometrical dimensions, the respective cables will have a conductor cross-section of 2 to 3000 mm ^{2 and an} outer cable diameter of 20 to 250 mm.

The power transformer or reactor windings made from the cable described in essence of the invention can be used for both single-phase, three-phase, and multiphase transformers or reactors, regardless of how the core is shaped. One embodiment is shown in Figure 9 where a three-phase laminated core transformer is shown. The core comprises, according to a conventional embodiment, three columns 60, 61 and 62 and retaining brackets 63 and 64. In the illustrated embodiment, both the core columns and the brackets have a tapered cross-section.

Wires made of cable are arranged concentrically around the core columns. As can be seen, the embodiment shown in FIG. 9 has three concentric windings 65, 66 and 67. The innermost winding 65 may be a primary winding and the other two windings may be a secondary winding. In order not to overfill the image with too much detail, the connections of the individual windings are not shown. Otherwise, this figure shows that in this embodiment there are certain locations around these windings

Φ · «·» · φ · 4 · • · · · · · • · · · · · 4 · 4 · φ · φ · Spacer bars 68 and 69 with several different functions are arranged. The spacer bars 68 and 69 may be made of an insulating material to provide some space between the concentric windings for cooling, expansion, etc. They may also be made of an electrically conductive material to form part of the grounding assembly of these windings. 9, no control windings 9 are shown.

Alternative cable design

In the cable variant shown in FIG. 10, the same reference numerals are used as before, only with the addition of reference numerals for this embodiment. In this embodiment, the cable 41a comprises a plurality of electrical conductors 42a that are separated from each other by insulation 44a. In other words, the insulation 44a serves both for insulation between adjacent electrical conductors 42a and between conductors 42a and the surrounding environment. The various electrical conductors 42a may be arranged in various ways that may be used to vary the cross-sectional shapes of the cable as a whole. In the embodiment of Fig. 10 it is shown that the conductors 42a are located in a straight line, which means a relatively flat cross-sectional shape of the cable. From this, it can be deduced that the cross-sectional shape of the cable can vary widely.

Referring to FIG. 10, it is assumed that there is less voltage than the phase voltage between adjacent electrical conductors 42a. More specifically, it is assumed that the electrical conductors 42a of Fig. 10 are made with different windings in the winding, which means that the voltage between these adjacent conductors is relatively low.

}

As before, there is an outer semiconductor layer 45a disposed outside of the insulation 44a made of a solid electrically insulating material. Around each of the above electric «· ♦ · · · · · · · · ·

6 9 9 9 99 9 9 9 9 9 9 9 9 9 9 9 9 9

9999 99 9 9 9 99 9 9 9

27, an inner layer 43a of semiconductor material is provided, i.e. each of these electrical conductors 42a is surrounded by its own inner layer 43a of semiconductor material. This inner layer 43a will therefore serve to equalize the voltage with respect to the individual conductors.

In the cable variant 41b shown in FIG. 11, the same reference numerals are used as before, only with the addition of the letter b, which is specific to this embodiment. Also in this case there are several conductors, more specifically, there are three electrical conductors 42b. It is assumed that there is a phase voltage between the conductors 42b, i.e. a substantially higher voltage than between the conductors 42a of the embodiment of Fig. 10. According to Fig. 11, there is an inner semiconductor layer 43b, with the conductors 42b disposed inwardly. Each of these electrical conductors 42b, however, is surrounded by a further own layer 70, with properties corresponding to those described above with respect to the inner layer 43b. Between each additional layer 70 and the inner layer 43b disposed around it is an insulating material. Therefore, the inner layer 43b will be present as a voltage equalization layer, outside of the further layer 70 of semiconductor material belonging to the electric conductors 42b, which additional layer 70 is connected to the respective electrical conductor 42b for arrangement at the same voltage as this conductor.

Possible adjustments

It is to be understood that this invention is not limited to the embodiments described above. Therefore, one skilled in the art can demonstrate that a number of detailed modifications can be made after the concept of the invention has been presented without departing from the concept as defined in the appended claims. As an example it is necessary

- 28 ·· · * · · · · · ·

9 9 *

9 9 99 9 8 9 ·

8 8 9 8 9 9

9 8 8 8 8

88 9 9 8 99

to emphasize that the present invention is not limited to the aforementioned examples of material selection. Functionally identical materials can therefore be used instead. With regard to the production of the insulation system according to the invention, it should be emphasized that it is also possible to use production techniques other than extrusion and spraying in order to achieve perfect contact between the different layers. It should further be emphasized that additional equipotential layers could be provided. For example, one or more equipotential layers of semiconductor material could be placed as insulation between those layers which are referred to above as "inner and" outer. Again, according to the invention, it is not normally assumed that it is necessary to form the control winding 9 using such a flexible cable as mentioned above as a result of the fact that one or more control windings normally have a lower voltage than the rest of the windings of the respective electromagnetic device. . More specifically, the remaining part of the winding may indeed be a high voltage winding. For the remainder, it should be emphasized that the precise control principle of carrying out the method of the invention can vary in a variety of ways within the scope of the intended control activity.

Claims (36)

An electromagnetic device comprising at least one magnetic circuit (1) and at least one electrical circuit (2, 3) comprising at least one winding (4, 5), wherein the magnetic and electrical circuits are inductively coupled to each other, the device further comprising a control arrangement (7) for controlling the operation of the apparatus, characterized in that the control arrangement (7) is adapted to control the frequency, amplitude and / or phase related to the electrical power to or from the apparatus by said control arrangement (7) comprising control means for controlling the magnetic flux in the magnetic circuit (1), said at least one winding (4, 5), or at least a portion thereof comprising at least one electrical conductor (42) provided with an insulating system consisting of an electrical insulation (44) formed a solid insulating material and an inner layer (43) disposed within this material, wherein said at least one electrical conductor (42) is disposed within the inner layer (43), wherein the electrical conductivity of the inner layer (43) is lower than the electrical conductivity of the electrical conductor (42) but sufficient for the inner layer (43) to control equalizing the electric field outside of the inner layer (43). Electromagnetic device according to claim 1, characterized in that the control means is formed by at least one control winding (9) inductively connected to the magnetic circuit (1). . 99,999 o • '·· ·· 8 9 9 9 9 9 9 9 999 9 9 9 9 • * * ·, · 9 9 9 9 9 9 9 9 9 9 9 9 9 9999 99 9.9 9 99 9 9 9 ~ 30 Electromagnetic device according to claim 1 or 2, characterized in that the control arrangement (7) is adapted to control the magnetic resistance in the magnetic circuit (1). Electromagnetic device according to claims 1 to 3, characterized in that the control arrangement (7) is adapted to add an additional magnetic flux to the magnetic flux in the magnetic circuit (1). An electromagnetic device according to claim 3, characterized in that the magnetic circuit (1) comprises a material having a permeability greater than 1, wherein the control arrangement (7) is adapted to control the magnetic resistance in the magnetic circuit (1) by changing the permeability of one or more. several such magnetic circuit regions (1) having variable permeability. An electromagnetic device according to claim 5, characterized in that the region or regions having variable permeability have one or more gaps in the magnetic circuit (1). Electromagnetic device according to claims 1 to 6, characterized in that the magnetic circuit (1) is free of a magnetic core. Electromagnetic device according to claims 1 to 6, characterized in that the winding is wound around the magnetic core (6). 99 9999 9 9 9 An electromagnetic device according to claim 2 or one or more of the other claims, characterized in that the control windings (9) and the windings (4, 5) of the electrical circuit are arranged to pass substantially the same magnetic flux. Electromagnetic device according to claims 1 to 9, characterized in that the device comprises a reactor adapted to be controlled by means of at least one of said control windings (9), frequency, amplitude and / or phase, relating to the electrical power passing through the winding (4). 5) electric circuit. Electromagnetic device according to claims 1 to 8 or 10, characterized in that the electric circuit (2) consists of at least two windings (23, 24) connected in series, the magnetic circuit (1j) consisting of at least two alternative paths. (18, 19) a magnetic flux, wherein the at least one control winding (9) is adapted to control the passage of the magnetic flux into one or both of these magnetic flux paths, the two windings (23, 24) of the electrical circuit (2) being positioned so that one of them is capable of being disconnected from the magnetic flux by said at least one control winding (9). Electromagnetic device according to claims 1 to 9 or 11, characterized in that the magnetic circuit (1) is arranged in a stator or rotor of a rotating electric machine. \ °] Ο · ·· ·· »♦ - 32 · 99 99 · · · 99 99 9! * 9 99 9 9 99 9 9 “· • 9 9 9 9 9 9 9 ft · · 999 99 99 Electromagnetic device according to claims 1 to 9, characterized in that the magnetic circuit (1) belongs to a transformer having primary and secondary windings (4, 5), the primary and secondary windings (4, 5) and the control windings (4). 9) are arranged to pass the same magnetic flux. , Electromagnetic device according to claims 1 to 8 in a transformer, characterized in that the secondary winding of the transformer consists of at least two winding parts connected in series, the magnetic circuit (1) consisting of at least two alternative magnetic paths (18, 19). at least two control windings (9b1, 9b2, 9c1, 9c2) are arranged to control the passage of the magnetic flux into one or both of these paths, the two winding portions of the secondary winding being positioned such that one of them is capable of being disconnected from the magnetic flux flow by said control windings. Electromagnetic device according to claims 11 and 14, characterized by: characterized in that it comprises a magnetic core having at least three arms connected in parallel, two of which arms belong to different magnetic flux paths, while the third arm is common to the two magnetic flux paths. An electromagnetic device according to claims 1 to 15, characterized in that the insulation assembly outside of said insulation comprises an outer layer (45) whose electrical conductivity is higher than the electrical conductivity of said insulation, allowing said outer layer (45), in connection 99 99 9 9 9 9 9 9 9 99 99 • 9 • 9 9999 98 · * · * • · 9 9 9 9 '9 9 9 9 99 999 - 33 with ground or otherwise, had a relatively low voltage, to control voltage equalization. An electromagnetic device according to claims 1 to 16, characterized in that the outer layer (45) is arranged substantially to close the electric field resulting from said electrical conductor (42) within the outer layer (45). An electromagnetic device according to claims 1 to 17, characterized in that the inner layer (43) and the rigid insulation have substantially the same thermal properties. An electromagnetic device according to claims 1 to 18, characterized in that the outer layer (45) and the rigid insulation have substantially the same thermal properties. Electromagnetic device according to claims 1 to 19, characterized in that the at least one conductor (42) forms at least one induction thread. An electromagnetic device according to claims 1 to 20, characterized in that the inner layer (43) and / or the outer layer (45) consist of a semiconductor material. Electromagnetic device according to Claims 1 to 21, characterized in that the inner layer (43) and / or the outer layer (45) have a resistivity in the range of 10 ⁶ Qcm to 100 kQcm, preferably 10 ³ to 1000 Qcm, in particular 1. up to 500 Qcm. φ \ ι market? 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 4444 44 99 ··· 94 4 · - 34 Electromagnetic device according to claims 1 to 22, characterized in that the inner layer (43) and / or the outer layer (45) have a resistivity which is in the range of 50 μΩ to 5 na per meter of conductor or insulation system. Electromagnetic device according to claims 1 to 23, characterized in that the solid insulation (44) and the inner layer (43) and / or the outer layer (45) are formed of a polymeric material. . Electromagnetic device according to claims 1 to 24, characterized in that the inner layer (43) and / or the outer layer (45) and the rigid insulation (44) are rigidly connected to each other substantially over the entire interface. ensuring consistency, also when bending and temperature changes. Electromagnetic device according to claims 1 to 25, characterized in that the rigid insulation (44) and the inner layer (43) and / or the outer layer (45) are made of a material having a high flexibility to maintain mutual cohesion under tension during operation. . An electromagnetic device according to claims 1 to 26, characterized in that the rigid insulation (44) and the inner layer (43) and / or the outer layer (45) are formed of a material having substantially the same modulus of elasticity. Electromagnetic device according to claims 1 to 27, characterized in that the inner layer (43) and / or the outer layer (45) and the rigid insulation (44) are formed of a material having substantially the same coefficient of thermal expansion. 9999 * 9999 9 9 9 · · · 9 9 99999 9 9 9 9 9 9 9 9 9 9 9900 99 99 999 - 35 Electromagnetic device according to Claims 1 to 28, characterized in that the conductor (42) and its insulating assembly form a winding formed by a flexible cable (41). Electromagnetic device according to claims 1 to 29, characterized in that the inner layer (43) is in electrical contact with at least one electrical conductor (42). Electromagnetic device according to claims 1 to 30, characterized in that said at least one electric conductor (42) consists of a plurality of strands, wherein at least one strand of electric conductor (42) is at least partially insulated and arranged in electrical contact with the inner layer (42). 43). Electromagnetic device according to claims 1 to 31, characterized in that the electric conductor (42) and its insulating assembly are designed for high voltage, in particular exceeding 10 kV, preferably exceeding 36 kV and more preferably exceeding 72.5 kV . Machine according to claim 12, characterized in that the magnetic circuit (1) comprises one or more magnetic cores (48) having grooves (50) for the windings (41). Electromagnetic device according to claims 12 and 32 to 33, characterized in that it comprises a generator, a motor or a synchronous compensator. '99 9999 99,999 9 9 9 9 9 9 9 · · · 999 9 9 9 9 9 9 9 9 9 9 9999 99 99 999 99 99 9 9 9 9 9 9 9 9 9 9 9 · - 36 Electromagnetic device according to claims 12 and 33 to 34, characterized in that it is directly connected to the high voltage power network, in particular 36 kV or more, without an intermediate transformer. An electromagnetic device according to claims 1 to 11 and 13 to 32, characterized in that it comprises a power transformer or a reactor.