EA002747B1 - Electricity supply system - Google Patents

Abstract

1. An electricity supply system for traction, comprising a 3-phase high voltage distribution line, a transformer station connected to two of the three phases of the distribution line or to a symmetrizing device converting three phases to two phases (e.g. a Scott connection), and having a transformer comprising a winding, and a traction supply line fed by the transformer station, characterised in that said winding includes insulation consisting of at least two semiconducting layers, each layer providing a substantially equipotential surface, and solid insulation between said semiconducting layers. 2. An electricity supply system for traction, comprising a 3-phase high voltage distribution line, a rotating converter connected to the three phases of the distribution line and having a winding, and a traction supply line fed by the rotating converter, characterised in that said winding includes insulation consisting of at least two semiconducting layers, each layer providing a substantially equipotential surface, and solid insulation between said semiconducting layers. 3. A system as claimed in claim 2, wherein high voltage switchgear is connected between the distribution line and the rotating converter. 4. A system as claimed in claim 3, wherein a transformer is connected between the switchgear and the rotating converter. 5. A system as claimed in claims 2, 3 or 4, wherein the frequency of the supply at the traction supply line is 25 Hz or 16 2/3 Hz. 6. An electricity supply system for traction, comprising a rotating converter adapted to be supplied by a 3-phase high voltage distribution line and having a winding the rotating converter supplying a single phase traction supply line and, via a first transformer, a high voltage intermediate line which is connected to the traction supply line via one or more further transformers, characterised in that said winding includes insulation consisting of at least two semiconducting layers, each layer providing a substantially equipotential surface, and solid insulation between said semiconducting layers. 7. A system as claimed in claim 6, characterised in that the winding of said first transformer includes insulation consisting of at least two semiconducting layers, each layer providing a substantially equipotential surface, and solid insulation between said semiconducting layers. 8. A system as claimed in claim 6 or 7, characterised in that the winding of the or each further transformer includes insulation consisting of at least two semiconducting layers, each layer providing a substantially equipotential surface, and solid insulation between said semiconducting layers. 9. An electricity supply for traction, comprising a rotating converter having a winding and adapted to be supplied by a 3-phase high voltage distribution line, the rotating converter supplying both a single phase lower voltage traction supply line and a high voltage intermediate line which is connected to said traction supply line via one or more transformers, characterised in that said winding includes insulation consisting of at least two semiconducting layers, each layer providing a substantially equipotential surface, and solid insulation between said semiconducting layers. 10. An electricity supply system according to claim 9, characterised in that the or each transformer has a winding including insulation consisting of at least two semiconducting layers, each layer providing a substantially a substantially equipotential surface, and solid insulation between said semiconducting layers. 11. An electricity supply system comprising a rotating converter having a winding and adapted to be supplied by a 3-phase high voltage distribution line, said rotating converter supplying a transformer which in turn supplies a traction supply line, characterised in that said winding includes insulation consisting of at least two semiconduct ing layers, each layer providing a substantially equipotential surface, and solid insulation between said semiconducting layers. 12. A system as claimed in claim any one of claims 2 to 11, wherein said rotating converter is synchronous. 13. A system as claimed in claim any one of claims 2 to 11, wherein said rotating converter is asynchronous. 14. A system as claimed in any one of claims 2 to 13, wherein said rotating converter comprises a single machine having both motor and generator functions. 15. A system as claimed in claim 14, wherein said rotating converter comprises a phase converter. 16. A system as claimed in claim 11, characterised in that the transformer has a winding including insulation consisting of at least two semiconducting layers, each layer providing a substantially equipotential surface, and solid insulation between said semiconducting layers. 17. An electricity supply system for traction, comprising at least one autotransformer having a winding and being connected between a traction supply line and a neutral line, characterised in that said winding includes insulation consisting of at least two semiconducting layers, each layer providing a substantially equipotential surface, and solid insulation between said semiconducting layers. 18. An electricity supply system for traction, comprising at least one current booster transformer having a winding and being connected between a traction supply line and a return conductor, characterised in that said winding includes insulation consisting of at least two semiconducting layers, each layer providing a substantially equipotential surface, and solid insulation between said semiconducting layers. 19. An electricity supply system for traction, comprising a static frequency converter unit connected between two transformers each having a winding, characterised in that said windings include insulation consisting of at least two semiconducting layers, each layer providing a substantially equipotential surface, and solid insulation between said semiconducting layers. 20. A system as claimed in any preceding claim, characterised in that at least one of said layers has substantially the same coefficient of thermal expansion as the solid insulation. 21. A system as claimed in any preceding claim, characterised in that the flux paths in the core of a magnetic circuit in the or each transformer or rotating converter consists of laminated sheet plate and/or rough forged iron and/or cast iron and or powder-based iron. 22. A system as claimed in any preceding claim, characterised in that the innermost semiconducting layer (32) which surrounds at least one conductor (31) is at substantially the same potential as the conductor(s) (31). 23. A system as claimed in any preceding claim, characterised in that the outer semiconducting layer (34) is connected to a selected potential. 24. A system as claimed in claim 22, characterised in that the selected potential is earth potential. 25. A system as claimed in any preceding claim, characterised in that a current-carrying conductor of the winding comprises a plurality of strands, only a few of the strands not being insulated from each other. 26. A system as claimed in any preceding claim, characterised in that said winding(s) and also permanently insulated connection conductors for high tension current between the system units are produced using a cable (6) with solid insulation for high voltage and comprising at least two semiconducting layers (32, 34), and also strands (36) which may be insulated or uninsulated. 27. A system as claimed in claim 26, characterised in that the high-voltage cables (6) have a conductor area of between 30 and 3000 mm<2> and have an outer cable diameter of between 10 and 250 mm. 28. A system as claimed in any preceding claim, characterised in that said winding can carry a rated voltage of 10 to 800 kV. 29. A system as claimed in claim 28, wherein said rated voltage is higher than 36 kV. 30. A system as claimed in claim 28, wherein said rated voltage is higher than 72.5 kV.

Description

Technical field

This invention relates to a power supply system for traction, i.e. to an electric power supply installation for railway locomotives, motor cars, trams and similar vehicles, in which at least one electric machine contained in the installation has a magnetic circuit containing a magnetic core and at least one winding.

State of the art

The magnetic circuit in an electric machine usually contains a lined core, for example, of sheet steel welded construction. To provide ventilation and cooling, the core is often divided into packages with radial and / or axial ventilation channels. For large machines, the core sheets are perforated in segments that are attached to the machine body, while the lined core is fastened with pressure pins or compression rings. The winding of the magnetic circuit is located in the grooves in the core, and the grooves, as a rule, have a cross section in the form of a rectangle or trapezoid.

In multiphase electric machines, windings are made either as single-layer windings or as two-layer windings. In the case of single-layer windings, there is only one side of the coil per groove; in the case of two-layer windings, there are two sides of the coil in one groove. Coil side means one or more wires combined vertically or horizontally and having common coil insulation, i.e., insulation made to withstand the rated voltage of the machine to earth.

Two-layer windings are usually made in the form of an equal-section winding, and single-layer windings in this context can be made in the form of equal-section windings or flat windings. In equal-section windings, there is only one (possibly two) winding width, while flat windings are made in the form of concentric windings, i.e., with a significantly varying coil width. Coil width means the distance in an arc between two sides of a coil related to the same coil.

Usually, all large machines are made with a two-layer winding and coils of the same size. Each coil is placed on one side in one layer and on the other side in the other layer. This means that all coils intersect at the end of the coil. If there are more than two layers, then these intersections complicate the operation of the winding, and the end of the coil is less satisfactory.

For historical reasons, several power supply systems with different voltages and frequencies have been developed for the operation of the railway. If one or another system has established itself in this area, then replacing it with another system involves significant costs and disruptions. Basically, there are three standard solutions for supply voltages, DC systems, AC voltage systems with a common frequency and AC systems with a low frequency. This meant that many traction vehicles (locomotives and motor cars) and passenger cars had to be designed for more than one power supply system. Currently, there are locomotives and wagons for unified communication between different countries, which can work with different power supply systems and / or with options within the same power supply system.

Electricity for traction trains can come either from a common distribution network, or can be generated at power plants of the railway itself. These decisions will be different depending on whether the power supply is AC or DC. In the case of direct current electrification, rectifier stations are required to convert the alternating voltage coming from the public distribution network. These rectifier stations supply constant voltage at specific points along the railway. In the case of electrification with alternating current having an industrial frequency (50 or 60 Hz), transformer filters are required at certain points to prevent harmonics generated in the thyristor electric drives of the locomotive from entering the system and public power supply facilities in order to balance traction loads. The conversion of three phases into two phases can also be carried out by a special connection of the transformer windings, for example, according to the Scott scheme. The disadvantage of this type of connection is that it requires a lot of windings and a significant mass of the core. Other disadvantages are that the power supply system with a common frequency has a low power transmission power and large losses of magnetic induction compared to the low-frequency system, and that the traction load forms disturbances in the network of supply lines. In the case of electrification with low-frequency alternating current (16 2/3 or 25 Hz), conversion stations are required for converting voltage from the industrial frequency of the public distribution network or special power plants and special distribution networks for low-frequency alternating current.

Electrification with direct current was originally chosen because of the availability of an appropriate and conveniently controlled motor, a DC motor with series excitation. Previously, three-phase alternating voltage was converted to direct voltage using rotary converters or mercury rectifiers, but currently the conversion is usually carried out using 6- or 12-pulse relays.

A DC voltage system has the advantage that current can be used directly in DC motors. To reduce the voltage, a heavy transformer in the vehicle is not required, as is the case with alternating voltage. Therefore, the manufacture of vehicles with constant voltage is somewhat cheaper and easier. Low DC voltage also has an advantage in terms of safety (for example, for underground railways where busbars are used, sometimes open).

The disadvantage of working with direct current is primarily the use of low voltage, and this means significant current loss and, consequently, a significant drop and voltage loss. This drawback should be compensated by a significant area of the wire and rectifier stations located at a close interval (usually less than 10 km between stations). As a result, power plants become more expensive. These disadvantages are especially noticeable in energy-intensive driving, such as high-speed driving. High power rectifier stations should be built close to each other, and they will only be used for a short time when the train passes by this power station. Another drawback is the extremely strong short circuit currents.

Before the use of industrial frequency (50 or 60 Hz) for traction motors became possible, the first AC systems were electrified with low frequency voltage (from 15 to 16 2/3 or 25 Hz). The traction motor used for a long time in these systems was a single-phase sequential commutator motor, also known as a single-phase traction motor. This motor functions as a direct current motor - with the exception that both the excitation current and the rotor current are turned into each half-cycle, since it is powered by alternating current. For switching in order to function without damaging overvoltages or electric arcs, it was necessary to use low frequency and low speed motors. The advantage of AC voltage with a low frequency compared to the frequency of common use is the best characteristics of the transmission of electricity.

The main advantage of AC systems compared to DC systems is that AC voltage can be converted (although at present DC voltage can be converted by so-called breakers). Therefore, it is possible to provide a relatively high voltage on the overhead line (OHL) wire relative to the voltage at which the engine operates. Due to the high voltage in the OHL wire, the current decreases, thereby improving the transmission characteristics of electricity and reducing losses in the line network. Power supply stations can be located far from each other (30 - 120 km). But at the same time, the drawback is that traction motors are bulky, and the control technique is complicated.

Another drawback is the need to have frequency converters in cases where motor generators are usually used, i.e., usually a 50 Hz synchronous motor, which drives a single-phase synchronous generator 16 2/3 Hz. For an asynchronous connection, the 50 Hz motor / generator is asynchronous due to a special rotor powered at a very low frequency of alternating current (Sherbius motor). Power can be supplied in both directions. The engine has three times the number of poles of the generator. Rotating converters are performed with a rather low rated voltage (6 kV) in order to avoid too powerful isolation. Therefore, in this case, transformers are required both before and after the converters. In the same power plant, several converters usually operate in parallel.

Rotary converters, which can be synchronous or asynchronous, can generate reactive power, which is able to compensate for the loss of reactive power that occurs in the network of the overhead line and in the vehicle. The rotary converter also provides electrical separation between the public distribution network and the OHL wire system. Reactive power can be routed to the public distribution network via a rotary converter.

The main disadvantage of rotating converters is that it takes a considerable time to start large synchronous / asynchronous machines, and phasing is complicated in them. It should be possible to meet the sharp increase in energy demand. Therefore, machines must be in operation without load or with low power for extended periods of time.

Another disadvantage is the energy loss, partially due to the mentioned work without load.

In new installations, rotary converters are replaced by static converters. Static converters can produce reactive power, which is able to compensate for the loss of reactive power that occurs in a suspended OHL wire. But the harmonics in this case are higher both on the three-phase and on the single-phase sides. In addition, static converters are not able to generate reactive power to compensate for the voltage drop caused by inductive load.

It clearly follows from the foregoing that the various systems used for electrified railways are relatively complex and expensive.

Machines of the type mentioned above with a traditional stator winding cannot be connected to a high voltage network, for example, 145 kV, without using a transformer in order to reduce the voltage. The use of the engine in this way with the connection to the high voltage network using a transformer is fraught with some drawbacks compared with the case when the engine can be directly connected to the high voltage network. Among others, the following disadvantages can be noted:

the transformer is expensive, it increases transport costs and it requires a place;

a transformer reduces the efficiency of the system;

transformer consumes reactive power;

a conventional transformer contains oil with inherent risks;

operation is complicated because the engine operates with a weaker network.

Description of the invention

The objective of this invention is to provide a power supply system and its components for the operation of an electrified railway, etc., which solves some of the problems existing in known systems of this technical field.

This invention provides a power supply system in accordance with any one of paragraphs. formulas 1, 2, 6, 9, 11, 17, 18 or 19, each of which has an identical distinctive part.

This invention is based on a special method of constructing electrical machines, motors, generators, transformers, etc., in which the electrical windings are made with dry insulation in a special way. This circumstance makes it possible either to eliminate the need for a transformer and / or to allow the design of transformers without the drawbacks inherent in the traditional transformers mentioned above.

The power supply system may include various types of machines in a single installation, configured to transmit electricity from the distribution network to the traction power supply line, which usually consists of a suspended OHL wire. You can also naturally conclude that one or more of these special machines can be combined with traditional machines.

Therefore, a machine of the type to which this invention relates can be a transformer or a motor-generator operating as a converter. Of course, these options can be combined.

The power supply system and components according to this invention can be made according to the requirements of different railway systems, and they are, with appropriate modifications, designed for railway systems with external power supply or with its own power generation system; for railways with different voltage levels and different frequencies, and both for alternating current systems and for direct current systems, and also for working with synchronous motors, as well as with asynchronous motors.

In cases where the use of a transformer is necessary, the objective of this invention is to manufacture a transformer using the same type of cable and using it in such a way that it matches other electric machines, including the power plant.

The advantage obtained by solving these problems is to eliminate the need for an intermediate oil transformer, the reactance of which consumes reactive power. Benefits are also provided in terms of network quality due to the availability of rotating compensation. When implementing a power plant according to this invention, the overload capacity is increased to + 100%, approximately. Compared with the prior art, the frequency and power control zone is increased according to this invention.

To solve the problems formulated above, the magnetic circuit and its wires, in at least one of the electrical machines that make up the power plant, are carried out with permanently insulated cable and grounding having conductors.

The main and significant difference between the prior art and the implementation of the present invention is that the invention is carried out using a magnetic circuit contained in at least one of the machines in a power plant, which is configured to directly connect to high voltage circuit breakers and insulators power supply - from 20 to 800 kV, preferably above 36 kV. The magnetic circuit contains one or more charged cores with a winding consisting of a cable core with one or more permanently insulated wires having a semiconducting layer both on the wire and on the outer side of the insulation, the outer semiconducting layer being connected to the Earth's potential.

To solve the problems arising from the direct connection of electric machines, and rotating and static machines to all types of high voltage power networks, at least one machine in the power plant according to this invention has a number of the above features, which clearly differ from the prior art. Other features and other embodiments are defined in the appended claims and are explained below.

The features mentioned above and other characteristics of the power plant and at least one of the electrical machines included in it according to this invention are as follows.

The winding for the magnetic circuit is made of a cable having one or more permanently insulated wires with two semiconducting layers, one of which surrounds the cores, and the other forms the outer sheath. Some typical wires of this type are insulated with structured polyethylene or ethylene-propylene rubber. For this purpose, the wires can also be made both in relation to the conductors in the wire, and in relation to the outer sheath.

Cables with a circular cross-section are preferred, but it is also possible to use, for example, some other cross-sections to improve the installation density.

Such a cable makes it possible to perform a lined core in accordance with this invention in a new and optimal way in terms of grooves and teeth.

The winding is preferably made with phased insulation for optimal use of the lined core.

The winding is preferably made in the form of a multilayer concentric cable winding, thereby reducing the number of crossings of the end of the coil.

The design of the grooves can be correlated with the cross section of the winding cable so that the grooves have the form of a number of cylindrical holes extending axially and / or radially from the outside of each other and having an open middle part extending between the layers of the armature winding.

The design of the grooves can be performed according to the corresponding cable cross-section and according to the phased insulation of the winding. Phased isolation allows the magnetic core to have a substantially constant tooth width regardless of radial extent.

The implementation described above with respect to cores provides for winding wires consisting of a number of compressed layers, i.e. insulated cores, which from the point of view of an electric machine are not necessarily correctly crossed, are uninsulated and / or insulated from each other.

The implementation described above with respect to the outer sheath assumes that at the corresponding points along the wire the outer sheath is cut off, with each partial length of the slice being directly grounded or connected to a similar selected potential.

The use of the cable of the type described above allows the entire length of the outer semiconducting layer of the winding and also other nodes of the power plant to be in the potential of the Earth. An important advantage is that the electric field approaches zero in the region of the end of the coil outside the outer floor of the conductive layer. With the potential of the Earth on the outer layer, there is no need to regulate the electric field. This means that neither in the core, nor in the zones of the end of the coil, nor in the transition between them, field concentrations arise.

The combination of insulated and / or non-insulated compressed cores, or intersecting cores results in low scattering losses.

The high voltage cable used in the winding of the magnetic circuit is made of an inner core / wire with many cores, at least one semiconducting layer, the innermost conductive layer surrounded by an insulating layer, which, in turn, is surrounded by an external semiconducting layer, having an external diameter of the order of 10 - 250 mm and a wire area of the order of 40 - 3000 mm ² .

According to a most preferred embodiment of the invention, at least two of these layers, preferably all three layers, have the same coefficient of thermal expansion. The decisive advantage obtained in this way is that defects, cracks, etc., do not occur during thermal displacement in the winding.

Since the insulation system, which is reasonably constant, is designed in such a way that, from the thermal and electrical points of view, it has dimensions corresponding to a voltage of more than 36 kV, the system can be connected to high voltage power supply networks without the use of an intermediate step-down transformer, thereby ensuring the benefits mentioned above.

The above and other preferred embodiments of the invention are defined in the dependent claims.

Brief Description of the Drawings

The invention is described in more detail in the following detailed description of preferred, but non-limiting embodiments with reference to the accompanying drawings, in which:

FIG. 1 is a schematic view of an end view of a stator sector in an electric machine in a power plant according to this invention;

FIG. 2 is an end view of a phased stripped cable used in the stator winding of FIG. one;

FIG. 3 is a schematic diagram of a power supply system comprising winding transformers according to the present invention;

FIG. 4 is a schematic diagram of a power supply system having a rotary converter;

FIG. 5 is an embodiment of a power supply system according to FIG. 4;

FIG. 6 is another embodiment of an electrical power system having a rotary converter;

FIG. 7 is an alternative embodiment of the power supply system shown in FIG. 6;

FIG. 8 is yet another embodiment of an electrical power system having a rotary converter;

FIG. 9 is a conventional power supply system containing a filtering and balancing load means;

FIG. 10 is an embodiment of the present invention for replacing the system of FIG. nine;

FIG. 11 is a circuit diagram depicting in more detail the embodiment of FIG. 10;

FIG. 12 is an embodiment of the present invention using boost boost current transformers; and FIG. 13 is an embodiment containing a static converter.

Description of Preferred Embodiments

In a schematic end view of the stator sector 1, according to FIG. 1, relating to an electric machine of a rotating type included in a power plant according to this invention, also shows the rotor 2 of the machine. The stator 1 consists of a traditionally lined core. FIG. 1 shows a sector of a machine corresponding to one pole division. A certain set of teeth 4 extends radially from the yoke 3 of the core to the rotor 2, and the teeth are separated from each other by grooves 5 in which the stator winding is laid. The cables 6 forming this stator are high voltage cables, which can be essentially the same type of cables that are used for power distribution, for example, structured polyethylene cables. The difference is that the outer sheath of the mechanical protection and the metal shielding, usually surrounding these power distribution cables, are not used here, as a result of which the cable used here contains only a wire and at least one semiconducting layer on each side of the insulating layer. Therefore, the semiconducting layer on the surface of the cable is not insulated.

Cables 6 are shown schematically in FIG. 1, wherein only the conductive central portion of each cable or side of the coil is shown. According to this image, each groove 5 has a varying cross section with alternating wide parts 7 and narrow middle parts 8. The wide parts 7 are substantially circular and surround the cable. The middle parts 8 between them serve to radially fix the position of each cable. The cross section of the groove 5 also tapers radially inward. This is because the voltage on the cables decreases as they approach the radially inner part of the stator 1. Therefore, thinner cables can be used in the inward direction, and thicker cables are needed in the outward direction. In the illustrated example, cables of three different sizes are used, made in sections of the corresponding size 51, 52, 53 grooves 5.

FIG. 2 depicts a phased stripped end view of a high voltage cable according to this invention. The high voltage cable 6 contains one or more wires 31, each of which contains a number of cores 36, which together give a circular cross section, for example, of copper (Cu). These wires 31 are located in the middle of the high voltage cable 6, and they are surrounded in the depicted embodiment by partial insulation 35. But this partial insulation 35 on one of the wires 31 can be omitted. In this embodiment, the wires 31 are together surrounded by a first semiconducting layer 32. Around this first semiconducting layer 32 is an insulating layer 33, for example, structured polyethylene insulation, which, in turn, is surrounded by a second semiconducting layer 34. Therefore, the high voltage cable according to This invention does not need to be placed in a metal shielding sheath or in an outer sheath of the type that usually surrounds such a cable for power distribution.

The above description of the magnetic circuit for rotating static electric machines made with cable 6 is also applicable to such static electric machines as transformers, reactor windings, and the like. A transformer having a cable winding according to FIG. 2, here called the transformer of the invention. From the point of view of manufacturing and design, the following important advantages are provided:

transformer windings can be performed without taking into account the distribution of the electric field, so there is no overlap of technical solutions from the prior art with the claimed technical solution;

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

oil is not required for the electrical insulation of the cable and winding, and instead the cable and winding can be surrounded by air or a non-flammable or slowly burning liquid;

the absence of oil significantly reduces the risk of fire and explosion in the transformer according to this invention, and therefore there is no need for a heat-insulating partition;

there is no need for a special installation having a means of collecting leaking oil;

this simplifies the design of an earthquake-resistant transformer;

the construction of a durable transformer is much simplified due to its stability against short circuits;

the transformer produces less noise, is cleaner, and its maintenance is reduced;

no special sleeve is required, as is the case with oil transformers, for the electrical connection between the external connections of the transformer and the coils / windings inside it; and the manufacturing and testing technique for the magnetic circuit transformer of the present invention described above is much simpler than for conventional transformers / reactors.

The use of electric machines with a magnetic circuit of the type described above greatly simplifies and makes more efficient the power supply of traction motors.

Some embodiments of the invention described below comprise a rotary transducer having at least one winding made of a wire according to FIG. 2, and referred to herein as the rotary transducer of the invention.

A rotating converter may contain a motor and a generator connected by a common shaft, or may contain one machine that functions both as an engine and as a generator, in accordance with the descriptions of German patents Nos. 372390, 386561 and 406371. Both the engine and the generator can be synchronous or asynchronous; moreover, the function of the rotating Converter is to change the voltage, number of phases and / or frequency of power supply. For railway systems with a frequency of common use, the rotating converter can be a phase converter, described in Liedeg Lex1soy Tesyshk, Ieii18yeg Uebadh-Apyan 81ibdag1, Vapb 2. p. 395, which also makes up a single car. It contains two-phase windings and three-phase windings in the stator and a squirrel-cage rotor.

In FIG. 3-7, a power supply system of the prior art is shown on the left for comparison with the embodiment of the present invention shown on the right.

FIG. 3 depicts a conventional system with a common frequency (50 or 60 Hz). A 3-phase high-voltage distribution line 40 feeds transformer stations, for example 41, 42 at several points along the railway. Transformer stations are powered from two phases of a three-phase distribution line. To balance the load, different combinations of phases are used. (So, station 41 uses AB; station 42 uses BC, and a nearby station (not shown) uses CA, etc.). Each transformer station comprises a high voltage switchgear 43, for example, two transformers 44, 45, and a high or medium voltage switchgear 46 (although one transformer per station may be sufficient). Between each two transformer stations, switchgear 47 provides the ability to connect sections 48, 49 of overhead lines of overhead lines to each other. In the depicted dual-track configuration, two overhead overhead wires, powered from the same station, are usually connected at this center point. In most cases, the connection of the overhead overhead wire cannot be made between two different transformer stations, since they are connected to different phases in the public network, and therefore such a connection will lead to unstable conditions. The disadvantage of this system is that the locomotive cannot be powered from both ends of the overhead wire. Therefore, transformer stations should be close to each other, usually at a distance of 30 km from each other. Transformers 44 in a prior art station 41 are oil-insulated and environmentally unsafe. A large amount of transformer oil is also flammable. They must be checked regularly for leaks. If other equipment is located close to the transformer, then there must be some protected space under the transformer so that in case of leakage the oil does not ignite. Transformers 44 often protect against damage by concrete walls around them. If the transformers are located close to other equipment or inside the building, firewalls are often erected around them to protect other equipment if the transformer oil ignites. Fire extinguishing equipment can also be installed around the transformer.

In contrast to the foregoing, transformers 45, according to this invention, do not contain any substance that can leak into the environment. Another advantage is that in case of fire, the flame will be much less intense. Transformer 45 can be installed on a much simpler basis, i.e. on a concrete site.

FIG. 4 depicts a typical low frequency system. A 3-phase high voltage distribution line 40 feeds the frequency converter stations, for example 51, 52, at several points along the railway. In each converter station, a three-phase high voltage with a common frequency is first converted to medium voltage. The three-phase medium voltage is then converted to a single-phase medium voltage low frequency. The known frequency converter 53 may be a static (not shown) or rotary type converter. A switchgear is installed on the high-voltage side of the transformer - between the transformer and the converter and the low-frequency side of the converter. A static converter is a converter transformer that converts the average voltage to a low six-phase voltage. In rare cases, this converter transformer can be powered directly from a high voltage switchgear. On the overhead wire of the VL 54, between two converting stations, a switchgear is installed to connect the sections of the overhead wire of the overhead lines to each other and for their synchronization. The advantage of this system compared to the common frequency system is that the locomotive can be powered from both ends of the overhead wire. Therefore, the conversion stations can be separated from each other even further, usually by 50 - 100 km.

The rotary transducer 54 shown on the right in FIG. 4 is a rotary transducer of the present invention. An advantage of this system is that the rotary converter 54 can be directly connected to the high voltage switchgear 55 without any intermediate transformer or switchgear. There is also no need to have a transformer on the medium voltage side, even if the voltage in the overhead wire of the overhead line is higher than 25 kV.

However, it may be necessary or economically feasible to provide a transformer between the 3-phase distribution line 40 and the rotary converter 54; and FIG. 5 depicts an alternative system comprising this transformer 56, which may be a transformer according to this invention.

FIG. 6 depicts a typical low frequency system used in Sweden. A 3-phase high voltage distribution line 40 feeds the frequency converter stations, for example 60, 61, at the most important points along the railway. At the converter station, a three-phase high voltage with a common frequency is first converted in the transformer 62 to medium voltage. The three-phase average voltage is then converted to a single-phase medium voltage of a low frequency by a known static frequency converter 63.

The single-phase low-frequency voltage is then connected to the overhead wire of the VL 64 and is also converted in the transformer 65 to a high voltage, i.e. up to 132 kV. This increased voltage is transmitted to transformer stations, in which the voltage is again converted to medium voltage, and connected to the overhead wire of the overhead line. A switchgear is installed on the high-voltage side of transformer 62 — between the transformer 62 and the converter 63, on the low-frequency side of the converter 63 and the high-voltage side of the single-phase transformer 65. The transformer stations between the converter stations have a high voltage switchgear on the high-voltage side of the transformer and a medium voltage switchgear on the other side transformer.

The advantage of this system compared to the common frequency system is that the locomotive can also be powered from both ends of the overhead wire. Another advantage is that the high voltage transmission to the transformer stations between the converter stations provides an opportunity to reduce the number of converter stations. The use of increased transmitted voltage (132 kV in Sweden) provides a more efficient transmission of electricity. Therefore, the total value of the installed power of the Converter can be reduced. Converting stations can therefore be placed at a greater distance from each other, usually -300 - 400 km. Transformer stations are placed every 20 - 40 km for the 16.5 kV and 16 2/3 kV systems (in Sweden).

On the right side of FIG. 6 shows a rotary converter 66, according to the present invention, between a high voltage switchgear 67 and a medium voltage switchgear 68. An advantage of this system is that the rotary converter 66 can be connected directly to a high voltage switchgear 67 without any intermediate transformer.

FIG. 7 depicts a system that is different from the system of FIG. 6 in that the rotary converter of the present invention 69 comprises a generator having two outputs that feeds both the suspension wire 64 and the high-frequency low-frequency line 70.

The right side of FIG. Figure 8 shows a typical low-frequency system used in Germany, Austria, Switzerland, and Ashtak in the United States. The 3-phase high-voltage distribution line 40 feeds the frequency converter stations, for example 80, at strategic points along the railway. At converter station 80, a three-phase high voltage common frequency is first converted to medium voltage. Then, a three-phase average voltage is converted to a single-phase medium voltage of a low frequency. The frequency converter may be static (not shown) or a rotating type converter. The single-phase low frequency voltage is then converted to high voltage, i.e. 138 kV. This increased voltage is transmitted to transformer stations, for example 81, located every 10 km for the 11 kV, 25 Hz system (in the USA) or every 20 to 40 km (in Sweden) along the railway between the converter stations. At these transformer stations, the voltage is again converted to medium and connected to the overhead wire of VL 82. A switchgear is installed on the high-voltage side of transformer 83 — between transformer 83 and converter 80, on the low-frequency side of converter 80 and on the high-voltage side of single-phase transformer 84. Transformer station 81 between converter stations has a high voltage switchgear on the high voltage side of its transformer 85 and a distributor medium voltage device on the other side of the transformer

85. This system has all the advantages of the systems of FIG. 6 and 7.

In accordance with one embodiment of the invention depicted on the left in FIG. 8, rotary converter

86, according to the present invention, is connected between a high voltage switchgear and a medium voltage switchgear. An advantage of this system is that the rotary converter 86 can be connected directly to a high voltage switchgear without any intermediate transformer or switchgear, and can be connected directly to a low frequency high voltage switchgear without any intermediate transformer or switchgear. Transformer 85 may be a transformer of the present invention.

FIG. 9 depicts a well-known principle for a system with a common frequency, for which a filter system 90 and a load balancing system 91 are required to balance the load and reduce disturbances coming from the public power network. To improve the voltage characteristics, autotransformers 92 can be installed along the overhead wire of VL 93. The use of autotransformers reduces interference for other systems. The overhead overhead wire is usually sectioned, and this reduces transmission capacity.

FIG. 10 shows that for the system with rotary converters 95, according to the present invention, the filters and load balancing equipment shown in FIG. 9, and that the overhead overhead wire can be synchronized, and it can connect power supply stations together. The output voltage and frequency of the rotary transducer 95 can be selected in a wide range. For a railway system with a frequency of common use, the rotary converter preferably comprises a phase converter, as described in Lsdcbhcbcbcbcrc.

FIG. 11 depicts in more detail schematic diagrams of the construction of an autotransformer. Autotransformers are used in public frequency systems and in low frequency systems. The interval between autotransformers is not very large, for example, 5 20 km. The fact that these transformers contain oil, usually around 5000 kg, which can leak and ignite, is environmentally disadvantageous.

An autotransformer 100 connected to a high or medium voltage switchgear 101 is an autotransformer according to the present invention and does not contain any substance that can leak out and enter the environment. Any ignition that occurs will be less intense, and the autotransformer 100 can be installed on a much simpler basis, i.e. on a concrete site.

Current is supplied to the locomotive only through the overhead wire of the overhead line. But the current can be supplied in several possible ways:

along the paths;

on the ground from any position on the tracks;

through underground wires connected to the tracks;

by leakage through metal in the ground: shielding sheaths, cables, pipes, fences, etc.

on the reverse current-carrying wire parallel to the overhead wire of the overhead line.

In most cases, reverse current-carrying wires are preferred, especially in densely populated areas where strong currents, such as those flowing through a gas pipeline, are dangerous. The current then flows through the return wire and other possible current paths.

If an AC system is used, current transformers with a 1: 1 ratio can be used. The return current in the return wire in this case is made the same as in the overhead wire of the overhead line. These transformers are often called boost boost current transformers. They can be used in systems with reverse current-carrying wires or without them.

A system with autotransformers is used not only to protect against unwanted reverse currents. This system also has increased bandwidth. This system has a reverse supply line with a voltage that deviates 180 ° from the phase with the voltage on the overhead overhead wire. A transformer is connected between two supply lines, and the center of the winding is connected to the paths.

FIG. 12 depicts an embodiment of the present invention including boost boost current transformers 110 according to the present invention. Booster current transformers are used both in systems with a common frequency and in systems with a low frequency. The interval between booster current transformers is not very large, for example, 2 - 5 km. The fact that these known booster boost current transformers contain oil, typically about 560 kg, which can leak and ignite, is environmentally disadvantageous. Booster current transformers 110 of the present invention do not contain any substances that may leak and enter the environment. Another advantage is that if ignited, the flame will be much less intense.

FIG. 13 is a single line diagram of a typical static converter. Two transformers according to this invention are shown in this device T1 and T2. The system of FIG. 13, is based on a known system containing oil-insulated transformers. Transformers T1, T2 do not contain any substances that can leak out and enter the environment. Any ignition that occurs will be much less intense, and transformers T1, T2 can be placed on a much simpler basis, i.e. on a concrete site.

The present invention is not limited to the systems described above with reference to the drawings, but includes all similar systems falling within the scope of the appended claims.

It is advisable that the insulating layer 33 be made of a solid thermoplastic material, such as low or high density polyethylene, polypropylene, polybutylene, polymethylpentene, an ethylene ethyl acrylate copolymer, from structured materials such as structured polyethylene, or have insulation made of rubber such as ethylene propylene rubber or silicone rubber. The semiconducting layers 32, 34 may contain a material similar to the insulating layer 33, but with conductive particles such as carbon black, carbon black or metal particles enclosed therein.

Although it is preferable that the electrical insulation be applied by extrusion, it is also possible to construct an electrical insulation system from tightly wound overlapping layers of film or sheet material. Semiconducting layers and an electrically insulating layer can be made in this way. The insulation system may be made of a fully synthetic film and external semiconducting layers, or of parts made of a thin polymer film, for example, polypropylene, polyethylene terephthalate or high density polyethylene with conductive particles incorporated therein, such as carbon black or metal particles, and with an insulating layer or with an insulating part between semiconducting layers or parts.

When overlapping, a sufficiently thin film will have butt gaps that are smaller than the so-called. Paschen's minima, thereby eliminating the need for liquid impregnation. Insulation made from a dry multilayer thin film also has good thermal properties.

Another example of an electrical insulation system is similar to a traditional cellulose-based cable, in which cellulose-based or synthetic paper or non-woven material is lapped around the wire. In this case, the semiconducting layers on both sides of the insulating layer can be made of cellulose paper or non-woven material made from fibers of the insulating material, and with the conductive particles included therein. The insulating layer may be made of the same base material, or another material may be used.

Another example of an insulating system is a combination of a film and a fiber insulating material, which may be laminated or overlapped. An example of this insulation system is the so-called industry-produced polypropylene paper laminate, but some other combinations of films and fiber insulation parts are also possible. In these systems, various impregnations can be used as mineral oil.

Claims (30)

CLAIM 1. A power supply system for a traction comprising a three-phase high voltage distribution line, a transformer station connected to two phases of a three-phase distribution line, or to a balun device converting three phases into two phases (eg, Scott connection), and having a transformer comprising a winding, and a power supply line powered by a transformer station, characterized in that said winding comprises an insulation consisting of at least two semiconducting layers, each layer of espechivaet substantially equipotential surface, and solid insulation between said semiconducting layers. 2. Power supply system for traction, comprising a three-phase high voltage distribution line, a rotary converter connected to three phases of the distribution line and having a winding, and a power supply line of a traction, characterized in that said winding contains insulation consisting of at least two semi-conductive layers, with each layer providing a substantially equipotential surface, and from solid insulation between said semiconducting layers. 3. The system according to claim 2, characterized in that the high voltage switchgear is connected between the distribution line and the rotating converter. 4. The system according to claim 3, characterized in that the transformer is connected between the switchgear and the rotating converter. 5. The system according to one of claims 2, 3 or 4, characterized in that the frequency of power supply in the power line of the traction is 25 or 16 2/3 Hz. 6. Power supply system for traction, comprising a rotary converter configured to be fed by a three-phase high voltage distribution line and having a winding, the rotary converter feeding a single-phase power line of traction and through a first transformer an intermediate high voltage line connected to the traction power line through one or more transformers, characterized in that said winding contains insulation, consisting of at least two semiconductors layers, each layer providing an equipotential surface, and of solid insulation between said semiconducting layers. 7. The system according to claim 6, characterized in that the winding of said first transformer comprises an insulation consisting of at least two semiconducting layers, each layer providing a substantially equipotential surface and solid insulation between said semiconducting layers. 8. The system according to one of claim 6 or 7, characterized in that the winding of the transformer or each additional transformer contains an insulation consisting of at least two semiconducting layers, each layer providing an equipotential surface, and of solid insulation between said semiconducting in layers. 9. Power supply for traction, comprising a rotary converter having a winding and configured to be powered by a three-phase high voltage distribution line, the rotary transformer feeding both a single-phase low voltage traction power line and an intermediate high voltage line that is connected to said traction power line through one or more transformers, characterized in that said winding contains an insulation consisting of at least two semiconductors of layers, each layer provides an equipotential surface, and solid insulation between said semiconducting layers. 10. The power supply system according to claim 9, characterized in that the transformer or each transformer has a winding containing insulation, consisting of at least two semiconducting layers, each layer providing an equipotential surface, and of solid insulation between these semiconducting layers. 11. A power supply system comprising a rotary converter having a winding and configured to be powered by a three-phase high voltage distribution line, said rotary converter energizing a transformer, which, in turn, energizing a traction power supply line, characterized in that said winding contains insulation, consisting at least two semiconducting layers, each layer providing an equipotential surface, and of solid insulation between semiconducting layers. 12. The system according to any one of claims 2 to 11, characterized in that said rotating transducer is synchronous. 13. The system according to any one of claims 2 to 11, characterized in that said rotary converter is asynchronous. 14. The system according to any one of claims 2 to 13, characterized in that said rotary converter comprises a single machine that performs the functions of both an engine and a generator. 15. The system of claim 14, wherein said rotary converter comprises a phase converter. 16. The system according to claim 11, characterized in that the transformer has a winding containing insulation, consisting of at least two semiconducting layers, each layer providing an equipotential surface, and solid insulation between these semiconducting layers. 17. Power supply system for traction, comprising at least one autotransformer having a winding and connected between the traction power supply line and a neutral wire, characterized in that said winding contains insulation consisting of at least two semiconducting layers, each the layer provides an equipotential surface, and of solid insulation between said semiconducting layers. 18. The power supply system for the traction, containing at least one booster current transformer having a winding and connected between the power supply line of the traction and the return wire, characterized in that the winding contains insulation, consisting of at least two semiconducting layers, moreover, each layer provides an equipotential surface, and from solid insulation between these semiconducting layers. 19. Power supply system for traction, containing a static frequency converter connected between two transformers, each of which has a winding, characterized in that said windings contain insulation, consisting of at least two semiconducting layers, each layer providing an equipotential surface, and from solid insulation between said semiconducting layers. 20. The system according to any preceding paragraph, characterized in that at least one of these layers has essentially the same coefficient of thermal expansion as solid insulation. 21. The system according to any one of the preceding paragraphs, characterized in that the core of the magnetic circuit in the transformer, or in each transformer, or in the rotary transducer contains lined sheet plate and / or forged iron and / or cast iron and / or powder iron. 22. The system according to any preceding paragraph, characterized in that the innermost semiconducting layer (32) that surrounds at least one wire (31) has essentially the same potential as the wire (a) (31) ) 23. The system according to any preceding paragraph, characterized in that the outer semiconducting layer (34) is connected to the selected potential. 24. The system according to item 22, wherein the selected potential is the potential of the Earth. 25. The system according to any preceding paragraph, characterized in that the current-carrying wire of the winding contains a plurality of cores, of which only some cores are not isolated from each other. 26. The system according to any one of the preceding paragraphs, characterized in that said winding (s) and also permanently insulated connecting wires for high voltage current between the system units are carried out using a cable (6) with solid insulation for high voltage, containing at least two semiconducting layers (32, 34) and also conductors (36), which can be insulated or non-insulated. 27. The system according to p. 26, characterized in that the high voltage cables (6) have a wire area of 30 to 3000 mm ² and have an outer cable diameter of between 10 and 250 mm. 28. The system according to any preceding paragraph, characterized in that said winding can carry a nominal voltage of 10 to 800 kV. 29. The system according to p. 28, characterized in that the specified nominal voltage exceeds 36 kV. 30. The system according to p. 28, characterized in that the specified nominal voltage exceeds 72.5 kV.