BG104516A - Electricity supply system - Google Patents

Abstract

An electricity supply system for traction comprises at least one transformer, for example an autotransformer or current booster transformer and/or a rotating converter. The transformer or rotating converter comprises a winding including insulation consisting of at least two semiconductor layers (32, 34), each providing a substantially equipotential surface, and solid insulation (33) between the semiconducting layers. 30 claims, 13 figures

Description

Technical field

The present invention relates to an electric power supply system for rail transportation, i. to an installation for the supply of electric locomotives, automotives, trams and similar vehicles, the installation of which includes at least one electric machine composed of a magnetic core and at least one turn.

BACKGROUND OF THE INVENTION

The magnetic circuit of an electric machine is typically composed of a laminated core, i. of steel sheets and is of closed construction. To provide ventilation and cooling of the core, it is most often divided into stacks with radial and / or axial ventilation ducts. For larger machines, the layered structures are stamped as segments that are attached to the yoke of the machine, and the laminated core is assembled through clamping fingers and rings. The winding of the magnetic circuit is located in the slots of the core, the slits typically having a rectangular or trapezoidal cross section.

In multiphase electrical machines, the windings are made either as single or double layer windings. For single-layer windings, there is only one side of the slot coil, while for two-layer turns, there are two sides of the slot coil. By "coil side" is meant one or more conductors combined vertically or horizontally and provided with ordinary coil insulation, i. E. with one insulation designed to withstand the rated voltage of the machine against the ground.

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Double-layer windings are typically made as template windings, while single-layer windings in the present context can be made as template or flat windings. In template windings, there is only one (possibly two) coil widths, while flat windings are made as concentric turns, ie. varying the width of the coil within a wide range. The "coil width" indicates the distance between the two sides of the coil belonging to the same coil.

Usually, all large machines are made with a double-layer winding and are the same size coils. Each coil is arranged on one side in one layer and on the other side in another layer. This means that all coils intersect at the end of the coil. If there are more than two layers, this intersection complicates winding work and the end of the coil is less satisfactory.

Due to historical reasons for electric rail transport, many power systems with different voltage and frequency have been upgraded. Once a system is set up in an area, changing the system requires enormous cost and disruption to work. Basically, there are three standard solutions for

voltage supply: direct voltage systems, public frequency alternating voltage systems and low frequency alternating voltage systems. This means that many electric rail vehicles (locomotives and automotives) and passenger motors must be built to operate more than one power system. There are now locomotives and shared traffic engines between different countries that can be operated by different power systems and / or variants in such power systems.

Electricity for rail transport can be supplied either from a common distribution network or generated at power stations, followed by a rail route. Performances vary depending on whether the power is AC or DC. In cases of constant voltage, electrification rectifiers are required to convert the AC voltage supplied by the public distribution network. These rectifying stations apply

constant voltage at certain points along the track. In the case of industrial frequency AC (50 or 60 Hz), filters are provided to protect the harmonic thyristor devices of the locomotive from being introduced into the public energy system and, at certain points, installations for balancing the electrical loads are required. transport. Three-phase two-phase transformation can be accomplished by connecting special transformers, for example, connecting Scott. The disadvantage of this connection is that it requires a lot of bends and a large mass of core. Another disadvantage is that the public frequency power supply system has a low power transmission capability and high inductive losses compared to the low frequency systems, as well as the line load generating interference to the power supply network. In the case of low frequency AC electrification (16¾ Hz or 25 Hz), the conversion stations are required to convert the industrial frequency of the public distribution network, or special power stations and special low frequency AC distribution networks.

Initially, DC was preferred because there was a motor with convenient and easy control 4 · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · ·

DC motor with serial excitation. The primary three-phase AC voltage was converted to direct voltage using rotary converters or mercury rectifiers with arc discharge, but now the conversion is usually performed with 6 or 12 pulse relays.

The DC system has the advantage of being current

can be used directly in DC motors. Heavy-duty transformers are not required in the vehicle for reducing the voltage as in AC. Voltage-powered vehicles are, at the same time, cheaper and easier to manufacture. Low DC voltage is also an advantage from a safety point of view (for example, in underground rails where busbars can sometimes be found).

The disadvantage of working with constant voltage is before

everything is low voltage, which means that the current, and therefore the voltage drop and loss, are significant. This should be offset by high conductivity areas and closely spaced rectification stations (usually less than 10 km between stations). This is reflected in expensive installations. The disadvantage is particularly noticeable at high capacities, such as high-speed traffic.

High-power rectification stations should be built close to each other and only used for a short time when the composition passes through the power station. Another disadvantage is the particularly high short circuit currents.

Before it became possible to use the industrial frequency (50 or 60 Hz) in transport motors, the first AC systems were for low-frequency electrification (15 to 16% or 25 Hz). The transport motor used for a long time in such systems was a single-phase motor with a series switch, also known as a single-phase transport motor. It functions as a direct current motor except that both the flow and the current of the rotor are reversed every half period because it is powered by alternating current. In order to make switching, in order to operate without the risk of overvoltage or electric arc at low frequency, low speed motors had to be selected. The advantage of low-frequency AC power compared to the public frequency is the better power transmission capability.

The main advantage of AC systems over DC systems is that AC voltage can be transformed (nowadays even DC voltage with so-called circuit breakers can be transformed). Therefore,

it is possible to maintain a relatively high voltage on the contact network with respect to the voltage at which the motor operates. Due to the high voltage in the power supply network, the current is reduced, which allows for better power transmission and reduced losses in the power line. Power stations can be located further (30 to 120 km). The disadvantage is that the transport bikes are large and the technology of their management is complex.

Another disadvantage is the need to convert the frequency at which motor generators would be used, i. a simple 50 Hz synchronous motor that runs on a single phase with a 16% Hz synchronous generator. For asynchronous coupling, the 50 Hz motor / generator is asynchronous with a special rotor powered by a very low frequency alternating current (Sherbius machine). Power can be supplied in two directions. The motor has three times more poles than the generator. The rotary converters are built for near normal voltage (6 kV) to avoid the use of insulation of such high quality. Transformers are required, both before and

• · · · · · · t ’·· after converters. Serial converters usually run in parallel in the same installation.

Rotary converters, which may be synchronous or

asynchronous, they can produce reactive energy that is able to compensate for the reactive energy losses occurring in the conduit network and in the vehicle. The rotary converter provides electrical separation of the public distribution network and the congested conduit system. Reactive energy can be supplied to the public distribution network via a rotary converter.

The main disadvantage of a rotary converter is that starting large synchronous / asynchronous machines takes time and is complicated. It must be possible to meet a sudden need for energy. As a limitation, it can be stated that the machines must be driven in the absence of load or at low power for extended periods. Another disadvantage is the loss of energy, which is partly the result of the aforementioned work in the absence of

goods.

In the new installations, the rotary converters were replaced by static converters. Static converters can produce reactive power that is able to compensate for the reactive power losses occurring in the contact network. The harmonics are higher than the three-phase and single-phase sides. Moreover, static converters are unable to generate reactive power to compensate for the voltage drop caused by inductive load.

As is clear from the above, the various systems used for electric rail transport are relatively complicated and expensive.

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Machines of the aforementioned type, with a conventional stator winding, cannot be connected to a 145 kV high-voltage network without the use of a voltage-reducing transformer. The use of a motor thus connected to a low-voltage network through a transformer entails a number of disadvantages compared to a motor that could be connected directly to a high-voltage network. Among other things, the following can be listed:

- the transformer is expensive, increases transportation costs and requires space;

- the transformer reduces the efficiency of the system;

- the transformer consumes reactive power;

- conventional transformer contains transformer oil, which is associated with risks;

involves sensitive work as the motor, through the transformer, struggles to run on a weak grid.

Description of the invention

It is an object of the present invention to provide an electrical power supply system and components thereto for electrical rail transportation, which solves some of the problems inherent in known systems in the art.

The present invention provides an electrical power supply system according to one of claims 1, 2, 6, 9, 11, 17, 18 or 19, each of which has the same characterizing part.

Thus, the invention is based on a special technique for designing electrical machines, motors, generators, transformers, etc., in which electrical windings are made with dry insulation in a special way. This allows or eliminates the · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · Transformer and / or transformer construction shall be free from the disadvantages inherent in the conventional ones mentioned above.

The feeder system may include machines of different types in single installations designed to transmit power from the distribution network to a line supplying a track, which usually consists of a contact network. Naturally, it may include one or more special machines combined with conventional machines.

Therefore, a machine of the type to which the invention relates may be a transformer or a generator motor operating as a converter. These alternatives can, of course, be combined.

The power supply system and components according to the invention can be adapted to the requirements of different electric rail systems, and with modifications, are intended for rail systems with external power supply or with their own power generation system, for rail transport at different levels on

voltage and at different frequency and for DC systems as well as for operation of synchronous and induction motors.

In the event that a transformer is supposed to be required, it is an object of the present invention that the transformer be manufactured using a cable of the same type and in a manner consistent with the other electrical machines included in the installation.

An advantage obtained by achieving the above objects of the invention is the avoidance of an intermediate oil-filled transformer whose reactivity otherwise consumes reactive power.

Advantages are also given to the quality of the power supply network, because rotary compensation is obtained. With an installation according to the invention, the overload capacity is increased to + 100%. The area of control is larger than the technology available.

To do this, the magnetic circuit and wires in at least one of the electrical machines included in the installation are manufactured with a coiled, permanently insulated cable and ground.

The main and main difference between the known technology and the embodiment according to the invention is that the latter is made with a magnetic circuit incorporating in at least one of the machines in the electrical installation, which is adapted for direct connection through switches and insulators to low power supply, in the range 20 800 kV, preferably higher than 36 kV. Therefore, the magnetic circuit contains one or more laminated cores of coils consisting of a wound cable having one or more pre-insulated conductors having one semiconductor layer, both on the conductor and externally on the insulation, with the outer semiconductor layer connected to the potential to the earth.

To solve problems arising from the direct connection of electrical machines and rotary and static machines to all types of high-voltage power grids, at least one machine in the installation according to the invention has many features, as mentioned above, that distinguish it sharply by known technology. Further features and further exemplary embodiments are defined in the dependent claims and are discussed below.

The above mentioned characteristics and other characteristics of the installation is that at least one of the electrical machines included in it according to the invention includes the following:

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99 99 99 9999

- The magnetic circuit winding is made of a cable having one or more pre-insulated conductors as well as two semiconductor layers, one covering the bundles of wires and the other forming an outer sheath. Some typical conductors of this type have cross-linked polyethylene (PEX) or ethylene propylene rubber insulation. For this purpose, the wires can be further refined, both with respect to the wiring harnesses and the outer sheath;

- Circular cross-section cables are preferred, but other cross-section cables may be used to provide, for example, better fill density;

- Such a cable allows the laminated core to be constructed according to the invention in a new and optimal manner with respect to the slots and teeth;

- It is preferable for the coils to be insulated in steps for the best use of the laminated core;

- Preferably, the coils are made as multi-layer, concentric cable coils, allowing the number of ends of the intermediate sections of the coils to be reduced;

- The slit construction may be suitably selected from the cross-section of the cable windings so that the slots are shaped in a series of cylindrical openings extending axially and / or radially outward from one another and having a projection disposed between adjacent wires. the habits;

- The design of the slits can be selected according to the section of the cable and the step insulation of the turns. Stepped insulation allows the magnetic core to have a nearly constant tooth width, regardless of radial propagation;

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- The aforementioned further refinements for sheaves result in the construction of conductors of conductors consisting of many tight layers / layers, for example, insulated sheaves, from the point of view of the electrical machine, not having to be arranged correctly , as well as being uninsulated and / or isolated from each other;

- The aforementioned further refinement of the outer shell has the consequence that, at appropriate points along the length of the conductor, the outer shell is interrupted, with any interruption parallel to the length and connected directly to earth or the like. selected potential.

Using a cable of the type described above allows the entire length of the outer semiconductor layer of the coil, as well as the rest of the installation, to be held to ground potential. One important advantage is that the electric field is near zero in the region of the edges of the coils outside the outer semiconductor layer. With the ground potential of the outer layer, the electric field does not need to be controlled. This means that there will be no concentration of the field either in the core, in the regions of the edges of the coils, or in the transition between them.

The mixture of insulated and / or uninsulated fastened bundles or displaced bundles is low loss of spurious capacities.

The high voltage cable used in the magnetic circuit is constructed of an inner core / conductor of multiple bundles, at least one semiconductor layer, the inner semiconductor layer is enclosed by an insulating layer, which in turn is covered by an external semiconductor layer having an outside diameter of the order of 10 - 250 mm and a conductive area with a cross section of the order of 40 - 3000 mm ² .

According to a particular preferred embodiment of the invention, at least two of these layers, preferably all three, have the same coefficient of thermal expansion. An undeniable benefit thus obtained is that defects, cracks, and the like are avoided during temperature movement in the windings.

As the insulation system, suitably permanent, is

Designed so that from a thermal and electrical point of view it is rated for a conductor voltage higher than 36 kV, the system can be connected to a high-voltage power supply network without any intermediate step-down transformer, whereby the advantages obtained relate to listed above.

The foregoing and other advantages of the invention are defined in the dependent claims.

Brief description of the drawings

The invention will be described in more detail in the following

a detailed description of preferred but non-limiting embodiments, with reference to the accompanying drawings, in which:

Figure 1 is a schematic view of a stator sector of an electric machine according to the invention;

Figure 2 is a view of a step-peeled cable used in the stator bends shown in Figure 1;

Figure 3 is a block diagram of a power system comprising transformers wound according to the invention;

Figure 4 is a block diagram of a power system having a rotary converter;

Figure 5 is a block diagram of an alternative embodiment of the power system of Figure 4;

• · · · ·

Figure 6 is a block diagram of another exemplary embodiment of

a power system having a rotary converter;

Figure 7 is a block diagram of an alternative embodiment of the power system of Figure 6;

Figure 8 is a block diagram of another exemplary embodiment of a power system having a rotary converter;

Figure 9 is a block diagram of a conventional power supply system comprising a filtering means and a load balancing means;

Figure 10 is a block diagram of an exemplary embodiment of the invention suitable to replace the power system of Figure 9;

Figure lie a more detailed diagram of an exemplary embodiment of the power system of Figure 10;

Figure 12 is a diagram of an exemplary embodiment of the invention using voltage-transformers;

Figure 13 is an exemplary embodiment including a static converter.

Description of preferred embodiments

In a schematic view of the stator sector 1 according to Figure 1, belonging to a rotary-type electric machine included in the installation according to the invention, part of the machine rotor 2 is also shown. Stator 1 is assembled as a conventionally laminated core. Figure 1 shows a sector of the machine corresponding to one pole step. Multiple teeth 4 extend radially into the yoke 3 of the core against the rotor 2 and are separated by slots 5 in which the windings are located. The stator winding cables 6 are high-voltage cables that can be of the same type as the one used to distribute energy, i.e. PEX cables. One difference is that the outer, protective sheath against mechanical damage and the metal sheath normally enclosing such a cable are eliminated so that the cable for this application contains only the conductor and most

little one semiconductor layer on each side of the insulating layer. Therefore, the semiconductor layer lies uninsulated on the surface of the cable.

Cables 6 are shown schematically in Figure 1 only through the central part of each cable or side of the coil that is inserted. As can be seen, each slit 5 has a variable cross section with varying width of the parts 7 and narrows 8. The wide parts 7 are substantially circular and encompassing the turn. The constrictions 8 between them serve to radially fix the location of each cable. The cross section of the slit 5 also narrows radially inwards. This is due to the fact that the voltage across the parts of the cable is lower, the closer they are radially to the inside of the stator 1. A similar winding can be used in the direction of the interior, where the coarser ones are laid cables must be pulled further. The illustrated example uses cables of three different sizes, arranged in three correspondingly sized sections 51, 52.53 of the slots 5.

Figure 2 shows the stepwise end of a high-voltage cable for an electrical machine included in the installation according to the invention. The high-voltage cable 6 contains one or more conductors 31, each of which consists of a plurality of bundles 36, which together have a circular cross section and are, for example, of copper (Cu). These conductors 31 are located in the middle of the high-voltage cable 6 and are surrounded in the exemplary embodiment shown by an insulating part 35. However, this part may be omitted for one of the conductors 31. In the present invention, the conductors 31 are covered together by the first • · • ··· • · · • ·· • ·· 9 9 9 9 9 9 9 9 9 9 9 9

9 9 9 9 9 9 9 9 9 9 9

99 99 99 99 99 semiconductor layer 32. Around this first semiconductor layer 32 has an insulating layer 33, for example, of PEX insulation, which in turn is covered by a second semiconductor layer 34. Therefore, the high-voltage cable does not need a metal screen or an outer sheath of the kind that typically encloses this type of power transmission cable.

The above arrangement of the magnetic circuit for a rotating electric machine constructed with cable 6 is also applicable to static electric machines, for example, transformers, chokes and the like. A transformer having a coil formed by a cable as shown in Figure 2 is hereinafter referred to as a "transformer of the invention". The following important advantages are a consequence from both a design and production point of view:

- Transformer bends can be constructed without taking into account any distribution of the electric field and, therefore, problematic crossing of parts in the known technology is not necessary;

- The transformer core can be constructed

without taking into account any electric field distribution;

- No oil is required to electrically insulate the cable and coils, and instead, the cable and coils may be covered by air or by a non-combustible or slowly burning liquid;

- The lack of oil significantly reduces the risk of fire and explosion in the transformer of the invention, therefore no fire protection walls are needed;

- No special foundation required for oil leakage;

• · · · · · · · · · · · · · ·

- It is much easier to design a transformer able to withstand earthquakes;

- Transformer can be made much easier,

due to its ability to withstand short circuits;

- The transformer is much quieter, cleaner and requires less maintenance;

- No special insulators are required for electrical connection between the external connections of the transformer and the coils / coils located inside it, as is the case with oil-filled transformers;

- The manufacturing and testing technology required for the magnetic circuit transformer of the invention, as described above, is significantly simpler than that required for conventional transformers / chokes.

The use of electric machines provided with magnetic circuits of the type described above ensures that the electric power supply to the traction motors is significantly simplified and more efficient.

Certain embodiments of the invention, which are described below, include a rotary converter with at least one winding formed by the conductor shown in Figure 2, hereinafter referred to as a "rotary converter of the invention". The rotary converter may comprise an engine and a generator connected by a common shaft, or it may comprise a single machine having both the functions of an engine and a generator, as described in German patents Nos. 372390, 386561 and 406371. The engine and generator many of them can be synchronous or asynchronous, and the function of the rotary converter is to change the voltage, the number of phases and / or the frequency of the power supply. For public rail systems, the rotary converter may be a phase converter as described in Lueger, Lexicon der Technik, Deutscher · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · ·

Verlags-Anstalt Stutgart, Band 2, p.395, also designated as a single machine. It contains two-phase windings and three-phase windings in

stator and short-circuited rotor.

In each of Figures 3 to 7, a known power system is shown on the left side of the figure for comparison with the exemplary embodiment of the invention shown on the right side of the same figure.

Figure 3 shows a typical public frequency system. A high-voltage distribution line 40 supplies transformer stations, e.g., 41, 42, located in several locations along the rail path. Each of the transformer stations is powered by two of the three phases of the distribution line. Different phase combinations have been used to balance the load. (So station 41 uses AB, station 42 uses BC, an additional station not shown in the figure, uses AA, etc.) Each transformer station consists of high-voltage switchgear 43, two transformers 44, 45 and high voltage or intermediate switchgear 46 (although a single transformer for a station may be sufficient). Between each two transformer stations, one switchgear 47 makes it possible to connect sections 48 and 49 of the contact network to each other. In the dual line configuration shown, the two wires of the contact network supplied by the same station are usually connected together at this central point. In most cases, the connection of the contact wire of the contact network cannot be made between two different transformer stations as they are connected to different phases of the public network and such connection would cause unstable conditions. The disadvantage of such a system is that a locomotive cannot be powered from either end of the contact wire. Transformer stations must be close to each other, usually 30 km away. Transformers 44 c

The prior art station 41 is insulated with transformer oil and is a threat to the environment. A large amount of transformer oil is also dangerous in the event of fire. They must be constantly checked for leaks. If there is other equipment near the transformer, there must be space under the transformer protected so that the oil cannot be reached by fire and where the oil can leak in case of leakage. Transformers 44 are often protected from danger by walls made of concrete and placed around them. If the transformer is located near other equipment or outside a building, firewalls are often built around the transformers to protect the other equipment in the event of a fire in the transformer oil. Fire extinguishers must be installed near the transformer.

In contrast, transformers 45 are transformers of the invention that do not contain anything inside them that can leak into the environment. Another advantage is that in the event of a fire, the fire will be extinguished in a much shorter time. The transformer 45 can be placed on a much simpler foundation, for example in a concrete socket.

Figure 4 shows a typical low frequency system. A three-phase high-voltage distribution line 40 supplies frequency conversion stations 51, 52 in several locations along the rail path. In each converter station, the three high frequency phases of public frequency are first lowered to intermediate voltage. The intermediate voltage in the three phases is then converted to a low frequency single phase intermediate voltage. The known frequency converter 53 may be static (as shown) or rotary. In the high voltage side of the transformer there is a switchgear and in the low frequency side of the converter - a converter. A static converter is a transformer transformer that converts the intermediate voltage into a low six-phase voltage. In rare cases, this transformer can be directly powered by the high-voltage switchgear. On the wire of the contact network 54 between the two conversion stations there is a switching apparatus providing

connecting sections of the contact network to one another and synchronizing them. One advantage of this system over the public frequency system is that a locomotive can be powered from both ends of the contact wire of the contact network. Transformation stations may be located farther apart, usually 50-100 km.

The rotary converter 54 shown on the right side of Figure 5 is a rotary converter of the invention. The advantage of this system is that the rotary converter 54 can be connected directly to the high-voltage switchgear 55 without intermediate transformers or switchgear. There is no need for any transformer in the intermediate side, even if the voltage of the contact wire is higher than 25 kV.

However, it may be necessary or cost effective to provide a transformer between the three-phase distribution line 40 and the rotary converter 54, therefore Figure 5 shows an alternative system comprising such a transformer 56, which may be a transformer of the invention.

Figure 6 shows a typical low frequency system implemented in Sweden. A three-phase high-voltage distribution line supplies frequency conversion stations 60, 61 at strategic locations along the rail route. In the conversion stations, the three phases of high-voltage public-frequency voltage are first converted into transformer 62 into intermediate voltage. The three-phase intermediate voltage is then converted to low-frequency single-phase intermediate voltage by a known static converter 63.

The low-frequency single-phase voltage is then connected to the mains conductor 64, but transformed through transformer 65 again to high voltage, 132 kV. This high voltage is transmitted to the transformer stations, in which this voltage is again lowered to intermediate voltage and connected to the contact wire of the contact network. The switchgear is provided in the high-voltage side of the transformer 62, between the transformer 62 and the converter 63, in the low-frequency side of the converter 63 and in the low-voltage side of the single-phase transformer 65. The transformer stations between the converter stations have high-voltage switching transformers switching equipment for intermediate voltage on the other side of the transformer.

The advantage of this system over the public frequency system is that a locomotive can be re-energized on both sides of the contact wire of the contact network. Another advantage is that the high voltage transmission to the transformer stations between the station converters makes it possible to reduce the number of station converters. The use of high transmission voltage (132 kV in Sweden) results in higher power transmission efficiency. The total capacity of the converters installed may be reduced. Conversion stations may be located at a larger · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · ·· distance from each other, usually 300 - 400 km. Transformer stations are located about 20 - 40 km on systems with 16.5, 16 ² L kV

(in Sweden).

The right side of figure 6 shows a rotary converter 66 of the invention, between the high-voltage switchgear 67 and the intermediate switchgear 68. An advantage of this system is that the rotary converter 66 can be connected directly to the high-voltage switchgear 67 without using any intermediate transformer.

Figure 7 shows a system different from that of Figure 6 in that the rotary converter 69 of the invention contains a single generator with two outputs, supplying both the contact wire 64 and the high voltage and low frequency line 70.

The right side of Figure 8 shows a typical low frequency system used in Germany, Austria, Switzerland and the USA. A three-phase, high-voltage distribution line 40 supplies frequency conversion stations 80 located strategically along the track. In converter stations 80, three-phase high voltage public frequency is first transformed into intermediate voltage. The three-phase intermediate voltage is converted to a low-frequency single-phase intermediate voltage. The frequency converter can be static (as shown in the figure) or rotary. The low frequency single phase voltage was then transformed into a high voltage 132 kV. This higher voltage is transmitted to transformer 81, located every 10 km for a system of 11 kV, 25 Hz (in the USA) or every 20 - 40 km (in Sweden) along the rail path between the conversion stations. In these transformer stations, the voltage is again lowered to intermediate and is connected to the contact wire of, · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · Мрежа 83 and the converter 80, in the low frequency country of the converter 80 and in the high voltage country of the single-phase transformer 84. The transformer station 81 between the converter stations has a high voltage utilization apparatus in the high voltage country of its transformer 85 and switching equipment on the other side of the transformer 85. This system has all the advantages of the systems shown in Figures 6 and 7.

According to one embodiment of the invention shown on the left side of Figure 8, a rotary converter 86 of the invention is coupled between a high voltage switchgear and an intermediate switchgear. The advantage of this system is that the rotary converter 86 can be connected directly to the high voltage switchgear without any intermediate transformer or switchgear and to be connected directly to the low frequency switchgear without any intermediate switch transformer or switchgear. Transformer 85 may be a transformer of the invention.

Figure 9 illustrates a known principle of a public frequency system requiring a filter system 90 and a system 91 for load balancing and to reduce interference transmitted to the public power system. Autotransformers 92 may be used to improve the voltage along the contact wire of the contact network 93. Interference with other systems is reduced by the use of autotransformers. The contact wire is usually sectioned, which reduces the possibility of propulsion.

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Figure 10 shows that the rotary converter system of the invention 95 does not require the filters and load balancing equipment shown in Figure 9 and that the contact wire can be synchronized and simultaneously connected to the power stations. The output voltage and frequency of the inverter 95 can be selected over a wide range. For a public frequency rail system, the rotary converter contains one phase converter as described in Lueger, “Lexicon der Technik”.

Figure 11 contains a detailed diagram of an autotransformer type. Autotransformers are used in both public frequency and low frequency systems. The distance between autotransformers should not be very long, for example, within 5 - 20 km. The fact that these transformers contain oil, typically about 5,000 kg, which can leak and ignite is bad for the environment.

The autotransformer 100 connected to the high or intermediate switching apparatus 101 is an autotransformer of

the invention and contains nothing inside that could leak into the environment. Any fire that may occur will be extinguished in a much shorter time and the autotransformer can be placed on a very simple foundation, for example in a concrete socket.

The current to the locomotive is transmitted only through the contact wire of the contact network. However, there are some possible parts that can conduct reverse current:

Through the rails;

Through the earth from any place along the line; Rails;

Through grounded wires connected to rails;

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Earth leaks such as cable sheaths, pipes, fences, and the like;

Reverse current conductors in parallel with the contact wire.

In most cases, backwaters should be preferred, especially in populated areas where large flows occur, for example, a gas pipeline is dangerous. The current will flow, both through the return conductor and through all possible conductive parts.

If a DC system is used, they can be

Transmission transformers used in a 1: 1 ratio. The return current in the reverse current conductor is forced to be the same as the current in the contact wire of the contact network. Transformers are often referred to as "current-added transformers". They can be used in systems with or without backwash.

An auto-transformer system has been used not only to provide protection against unwanted back currents. Such a system also has a higher drive capability. The system has a negative supply line with a voltage that is rotated 180 ° to

the voltage of the contact wire of the contact network. The transformer is connected between the two feeders and the center of the coil is connected to the rail.

Figure 12 shows an exemplary embodiment comprising current-adding transformers 110 of the invention. Current transformers are used in both public frequency and low frequency systems. The distance between current transformers and transformers is not very large, for example, from 2 to 5 km. The fact that known current-voltage transformers contain oil, typically 560 kg, which can leak and ignite is bad for the environment. The current-adding transformers of the invention 110 do not contain anything inside that is capable of being transformed. · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · Another advantage is that in the event of a fire, the fire will be extinguished much faster.

Figure 13 is a diagram of a single-phase static converter.

There are two transformers of the invention Tj and T ₂ . The system of Figure 13

is adapted to the known system containing oil-insulated transformers. Transformers Τι and T ₂ contain nothing inside that can leak into the environment. Any fire will be suppressed much faster and transformer T] and 'D ₂ can be located at a much simpler foundation, for example, in concrete wells.

The invention is not limited to the systems described above with reference to the attached drawings, but embraces such systems within the scope of the appended claims.

Typically, the insulating layer 33 is composed of a rigid thermoplastic material, for example low or high density polyethylene, polypropylene, polybutylene, polyethylene, ethyl ethyl acrylate copolymer, cross-linked PEX or rubber materials

insulation of the type ethylene propylene rubber or silicone rubber. The semiconductor layer 32, 34 may contain a material similar to that of the insulating layer 33, but with conducting particles introduced therein, for example, carbon black, carbon black or metal particles.

Although it is preferable for the electrical insulation to be particles, for example, of carbon black or metallic particles, and extruded, it is possible to construct an electrical insulation system of tightly wound film or sheet-like overlapping layers. The two semiconductor layers and the electrical insulation layer can be formed as follows. An insulation system may be made of a fully synthetic film with internal and external semiconductor layers or parts made of a polymeric thin film, for example, PP, PET, LDPE or HDPE, with conductors introduced therein.

• · · · ft ft · ft ft ft ft ·· ·· ·· ·· ft · · one insulating layer formed between the two semiconductor layers or parts.

According to the theory of winding a sufficiently thin film, gap gaps smaller than the so-called minimum Paschen minimum will be formed, therefore the application of liquid impregnation is not necessary. A dry-coated multi-layer thin film insulation also has good thermal properties.

Another example of an electrical insulation system is similar to

conventional cellulose cable insulation in which thin cellulose or synthetic paper or non-woven material is wound with overlap around the conductor. In this case, the semiconductor layers, on each side of the insulating layer, may be cellulose paper or non-threadbare material made of insulating material made of filaments and conductive particles introduced. The insulation layer may be made from a material on the same base or another material may be used.

Another example of an insulation system is obtained by

combining film and fiber insulation material, either as laminate or by overlapping. An example of such an insulation system is commercially available on the so-called laminated polypropylene paper, PPLP, but other combinations of film and filamentary particles are possible. Various inclusions such as mineral oils can be used in these systems.

Claims (30)

Patent Claims 1. An electric power supply system for rail transportation comprising a three-phase high-voltage distribution line, a transformer station connected to two of the three phases of the distribution line, or to a symmetrical device converting the three phases into two phases (eg Scott connection) and having a transformer comprising a coil, and a feed line for the track through the transformer station, characterized in that said coil contains insulation consisting of at least two semiconductor layers, each layer providing substantially equipotential surface, and solid insulation located between the two semiconductor layers. 2. An electric power supply system for rail transport comprising a three-phase high-voltage distribution line, a rotating converter connected to the three phases of the distribution line, and having one winding, and a supply line for the rail path through the rotating converter, characterized in that said winding includes insulation composed of at least two semiconductor layers, each layer providing one substantially equipotential surface, and a solid insulation layer between said semiconductor layers. 3. The system as claimed in claim 2, wherein the high-voltage switchgear is connected between the distribution line and the rotary converter. A system as claimed in claim 3, wherein a transformer is connected between the switchgear and the rotary converter. A system as claimed in claims 2, 3 or 4, in which the power supply frequency of the rail feed line is 25 Hz or 167hz. 6. Electric rail feed system comprising a rotary converter adapted to be powered by a three-phase high-voltage distribution line and having a winding, a rotary converter, a single-phase feed line for power supply to a rail path by means of a first transformer, a high-voltage intermediate line, supplying the track through one or more subsequent transformers, characterized in that said winding comprises insulation consisting of at least two semiconductor layers, each and a layer providing a substantially equipotential surface and solid insulation between said semiconductor layers. System as claimed in claim 6, characterized in that the winding of said first transformer comprises an insulation consisting of at least two semiconductor layers, each layer providing substantially an equipotential surface, and solid insulation between said semiconductor layers. System as claimed in claim 6 or 7, characterized in that the winding of each transformer comprises 9 insulation consisting of at least two semiconductor layers, each layer providing substantially equipotential surface and insulation between said semiconductor layers. 9. An electric power supply system for rail transport comprising a rotary converter having a coil and adapted to be powered by a three-phase high-voltage distribution line, the rotating converter supplying, both a single-phase low-voltage power supply to a rail path and a high-voltage interconnected interconnecting line. a supply line of the track through one or more transformers, characterized in that said winding comprises insulation composed of at least two semiconductor layers, each layer providing a substantially equipotential surface, and solid insulation layer between said semiconductor layers. An electrical supply system according to claim 9, characterized in that each transformer has a coil comprising insulation composed of at least two semiconductor layers, each layer providing a substantially equipotential surface, and a solid insulator between said semiconductor layers. 11. An electrical power supply system comprising a rotary converter having the habit of being adapted to be powered by a three-phase high-voltage distribution line, and said rotary converter being a power transformer, which feeds a line for supplying the rail path, characterized in that it is mentioned it consists of at least two semiconductor layers, each layer providing a substantially equipotential surface, and solid insulation between said semiconductor layers. MMYJ1 • · · · • · • • · • · • · ·· • · • · · • · • · • · · · • · • · • · • · ·· ·· ·· 9 · • · ·· A system as claimed in any one of claims 2 to 11, wherein said rotary transducer is synchronous. A system as claimed in any one of claims 2 to 11, wherein said rotary transducer is asynchronous. A system as claimed in any one of claims 2 to 13, wherein said rotary converter is a single machine having both motor and generator functions. A system as claimed in claim 14, wherein said rotary converter is a phase converter. System as claimed in claim 11, characterized in that the transformer has a winding comprising insulation consisting of at least two semiconductor layers, each layer providing a substantially equipotential surface, and a solid insulator between said semiconductor layers. 17. An electric power supply system for rail transport comprising at least one autotransformer having a winding and connected between the power line of the railroad and a neutral line, characterized in that said winding comprises an insulation consisting of a little two semiconductor layers, each layer providing one substantially equipotential surface, and solid insulation between said semiconductor layers. • · · · · 18. An electrical power supply system for rail transport comprising at least one current-carrying transformer having a coil and connected between a power supply line of the rail and a return conductor, characterized in that said coil contains at least two insulation semiconductor layers, each layer providing one substantially equipotential surface, and solid insulation between said semiconductor layers. 19. An electrical power supply system for rail transport comprising a static frequency converter connected between two transformers, each of which has a winding, characterized in that said winding comprises insulation consisting of at least two semiconductor layers, each layer providing, essentially an equipotential surface, and solid insulation between the two semiconductor layers mentioned. 20. A system as claimed in any preceding claim, wherein at least one of said layers has substantially the same coefficient of thermal expansion as the solid insulation. 21. System as claimed in any preceding claim, characterized in that the parts of the flow in the core of the magnetic circuit of each transformer or rotary converter are of laminated flat plates and / or raw wrought iron and / or cast iron and / or or pressed with metal powders. · · · · · · · · · · · · · · · · · · · · · A system as claimed in any one of the preceding claims, characterized in that the inner semiconductor layer (33) has substantially the same potential as the conductor (s) (31). System as claimed in any of the preceding claims, characterized in that the outer layer (34) is connected to a selected potential. A system as claimed in claim 22, characterized in that the selected potential is the potential of the displacement. A system as claimed in any of the preceding claims, characterized in that the winding conductor of the winding consists of multiple bundles, with only some of the bundles not isolated from the rest. 26. A system as claimed in any preceding claim, characterized in that said winding and permanently insulated connected high current wires between the system blocks are made by using a high voltage solid insulation cable (6). consisting of at least two semiconductor layers (32, 34) and bundles (36) that can be isolated or non-insulated. 27. A system as claimed in claim 26, characterized in that the high-voltage cable (6) has a conductive · · · · · · · · · · · · · · · · · · · · · · · · 9 99 9 9 9 9 9 9 9 9 9 9 99 99 99 ·· ·· 9999 area with cross sections of 30 and 3000 mm ² and an outer cable diameter of between 10 and 250 mm. 28. A system as claimed in any of the preceding claims, characterized in that said winding can conduct a rated voltage of 10 to 800 kV. 29. A system as claimed in claim 28, wherein said rated voltage is greater than 36 kV. 30. A system as claimed in claim 28, wherein said rated voltage is greater than 72.5 kV.