RU2847767C1 - Mobile transformer substation with a quick-assembly electrical network - Google Patents

Abstract

FIELD: electric power engineering.

SUBSTANCE: invention relates to electric power engineering, namely to mobile transformer substations. The mobile transformer substation includes a transformer with high- and low-voltage switchgear. It is equipped with a transformer with a rated voltage of 10(6)/0.4 kV with a three-core steel core with primary and secondary windings of phases A, B and C, and a power cable comprising a single-wire copper conductor with a cross-section of 2.5 mm², having a face-centred crystal lattice with unidirectional metal grain sizes, obtained by thermoplastic deformation, on top of which a silane-crosslinked composition based on an electrical insulating material with the addition of an aqueous crosslinking catalyst is applied, on top of which a copper foil screen is located, connected to a 6-10 kV overhead power line.

EFFECT: ensuring the possibility of rapid comprehensive organisation of power supply to consumers in conditions where it is impossible or there is insufficient time to connect to a stationary electrical network.

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Description

The invention relates to the electric power industry, namely to mobile transformer substations with a quickly erected electric network and can be used for the transmission, conversion and distribution of electric energy with a nominal voltage of 10(6)/0.4 kV (nominal voltage 10(6)/0.4 kV means the designation of a step-down substation, where 10 kilovolts is the voltage of the primary winding, 0.4 kilovolts is the voltage of the secondary winding).

When connection to the fixed power grid is unavailable or time-consuming, it becomes necessary to supply electricity to consumers. Such consumers may include low-power customers, such as rotational camps at natural resource deposits, construction sites, agricultural facilities, and temporary facilities deployed by units, including those deployed during emergency situations by the Ministry of Emergency Situations and the Ministry of Defense of the Russian Federation.

Typically, such consumers have predominantly single-phase loads, and some have increased deployment time requirements. Power supply from diesel generators alone is not always economically feasible and is difficult. Furthermore, diesel generators have increased noise levels, exceeding the requirements of consumers such as the Ministry of Emergency Situations and the Ministry of Defense of the Russian Federation.

A mobile transformer substation (RU215931 U1, published on 10.01.2023, IPC: H02B 7/01) mounted on a wheeled chassis is known from the prior art, including a high-voltage transformer with a gas-insulated bushing connected to a high-voltage power transmission line, with a gas-insulated cooling system, a low-voltage transformer connected by means of movable buses to the gas-insulated terminal of the high-voltage transformer, wherein the substation is designed with the possibility of connection to an integrated automatic control system.

Also known is a 35 kV mobile transformer substation (RU145940, published on September 27, 2014, H02B 7/01), comprising a power transformer, a high-voltage input complete device, and a low-voltage complete device installed in a closed block container, connected by means of jumper cables to a power transformer connected to a high-voltage line through a high-voltage complete device equipped with an input disconnector. The high-voltage complete switchgear and the power transformer are installed in closed block containers. The block container consists of two compartments, one of which houses the high-voltage equipment. The block container with the low-voltage complete switchgear is divided by a partition into two compartments, one of which houses the substation control board, and the other the low-voltage complete switchgear. The utility model is aimed at improving the ease of use and reliability in operation, ease of maintenance and placement.

Also known is a mobile complete transformer substation (RU2766318, H02B 7/00, publication date 2022.03.15), consisting of two units placed on wheeled semi-trailers. The first semi-trailer houses an open block-container in which a power transformer and a complete high-voltage input device with a high-voltage switch are installed; a measuring current transformer; a measuring voltage transformer; a surge suppressor; an auxiliary power transformer; a horizontal-rotary disconnector with a drive; an open 35 kV air-insulated high-voltage input complete device and a power transformer are located inside the frame of the frame and are electrically connected by a busbar jumper. The second semi-trailer houses a complete low-voltage device in a closed block-container in the form of a closed frame framework. Electrical communication between the units is accomplished via cable. The invention aims to simplify the transformation of a mobile transformer substation from operational to transport mode and vice versa, facilitating both road transportation on roads appropriate to the substation's dimensions and weight, as well as transportation in poor road conditions and off-road conditions, such as on wheels, by drag, or by helicopter.

Known mobile transformer substations have common design flaws: they cannot be quickly connected to a 35 kV high-voltage power line (HVPL) without first disconnecting the line. Furthermore, substations can only be installed at a distance of no more than 50 meters from the HVPL, as no other method for connecting a mobile transformer substation to a HVPL is known from the state of the art (35 kV overhead cables do not exist, and type A, AC, MG cables, etc., lack protective insulation). All this limits the use of substations in situations where a rapid power supply is needed, such as in emergency zones or in hard-to-reach locations where there are no HVPLs within a radius of more than 50 meters.

In addition, according to sanitary regulations, high-voltage wires must be located at a safe distance from residential areas. Connecting substations to 35 kV power lines via flexible busbars requires fencing the connection point to prevent electric shock or arc discharge.

The technical objectives of the invention are to create an improved mobile substation with a quickly erected electrical network without the need to disconnect the power transmission line, with the ability to transmit electricity over long distances of up to 50 km from the 6-10 kV power transmission line, and the ability to supply electricity to facilities in conditions where there is no possibility of connecting to a stationary electrical network or the impossibility of delivering fuel for generating electrical energy in hard-to-reach places (water, mountainous, wooded areas).

The technical result of using the invention consists in increasing the ability to quickly and comprehensively organize the supply of electricity to consumers in conditions where there is no possibility or insufficient time to connect to a stationary electrical network with a different nominal voltage class of 10 kV or 6 kV.

The technical result is achieved due to the fact that the mobile transformer substation with a quickly erected electrical network includes a transformer on a wheeled base with high- and low-voltage distribution devices equipped with an electric energy meter and with an installed reel for winding a power cable. The substation is equipped with a transformer with a rated voltage of 10(6)/0.4 kV with a three-rod steel core with primary and secondary windings of phases A, B and C and a power cable including a copper single-wire conductive core with a cross-section of 2.5 ^mm2 , on top of which a silane-crosslinkable composition based on an electrical insulating material with the addition of a water crosslinking catalyst is applied, on top of which a copper foil screen is located, connected directly to an overhead power line of 6-10 kV, wherein the cable is connected through a high-voltage switchgear to the contact tips of the high-voltage inputs of the 10(6)/0.4 kV transformer, and a low-voltage switchgear is connected to the contact tips of the low-voltage inputs of the transformer.

The proposed solution is illustrated by the following materials.

Fig. 1 shows a mobile transformer substation connected to a 6-10 kV overhead power line.

Fig. 2 shows a variant of connecting a substation to a 6-10 kV overhead power line through open-pit quarry cells.

Fig. 3 shows a diagram of the implementation of the invention using the example of laying a linear section of an electrical network in hard-to-reach places at a considerable distance from a high-voltage power line.

The mobile transformer substation with a quickly erected electrical network includes a 10(6)/0.4 kV transformer (1), high (2) and low (3) voltage distribution devices of the RME type, an electric energy meter (not shown in the diagram), installed on a wheeled base with increased ground clearance (4) for transportation and with the ability to connect to small-sized and highly mobile vehicles.

The 6(10)/0.4 kV power transformer has a three-rod steel core with the primary and secondary windings of phases A, B and C located there. The magnetic fluxes of the three phases in symmetrical modes circulate in the transformer core and do not go beyond its limits.

For the purposes of this application, increased ground clearance is defined as the distance from ground level (the supporting plane) to the lowest structural element of the vehicle, excluding the wheels (usually this is the distance to the crankcase or its guard) from 200 to 450 mm. Higher ground clearance facilitates off-road driving.

In order to achieve the technical result, the mobile transformer substation is also equipped with a power cable (4) with the specified characteristics. The power cable used contains a single-wire copper conductive core with a cross-section of 2.5 mm2, having a copper microstructure with a unidirectional arrangement of its grains, obtained by thermoplastic deformation by drawing at a temperature in the tool at the contact point of 200-250 °C with the use of a cooling and lubricating liquid for the workpiece and tools, with subsequent heat treatment per pass at a floating temperature of about 350 °C, with the simultaneous effect of an electric current having a voltage of 12-24 V and a current of 2500 - 3500 amperes, wherein a silane-crosslinkable composition based on an electrical insulating material with the addition of an aqueous crosslinking catalyst is applied over the copper single-wire conductive core, over which a copper foil screen is located.

The single-wire copper conductive core has a face-centered crystal lattice with unidirectional metal grain sizes. A silane-crosslinkable composition based on an electrical insulating material (e.g., polyethylene) is extruded onto the conductive portion. This composition incorporates an aqueous crosslinking catalyst containing a complex of stabilizers. This ensures resistance to aggressive environmental factors, oxidative degradation, and high thermal stability during processing, depending on the thickness of the insulating layer and the calculated voltage. The use of copper metal, which has a microstructure with a unidirectional arrangement of its grains, obtained by thermoplastic deformation by drawing at a temperature in the tool at the point of contact of 200-250 °C with the use of a cooling lubricating liquid for the workpiece and tools, followed by heat treatment per pass at a floating temperature of about 350 °C, with the simultaneous action of an electric current having a voltage of 12-24 V and a current of 2500 - 3500 amperes.

This power cable enables transmission of up to 250 kW of power over a single-wire copper conductor with a diameter of 2.5 mm² over distances of up to 10 km. This is possible because the cable's conductive portion carries an increased electric current, dependent on the applied voltage, and transmits high power through a small-gauge conductor. This means that the electric current depends on a high voltage (10,000 volts) and minimal current (less than 1 ampere) with a constant conductor resistance. This enables the transmission of high power through a small conductor cross-section.

In a static state, the power cable is wound onto a lightweight reel (5) to enable the installation of an electrical network.

The transformer (1), high (2) and low (3) voltage distribution devices with an electric energy meter are designed with the possibility of being connected to each other by means of a power cable (4).

The low-voltage distribution device (3) contains, inside a sealed housing, an automatic transfer switch (ATS) for consumer backup and increased reliability of power supply, and a device for transferring consumers on the low-voltage side to line voltage when connected to a 6 kV network.

Due to the described characteristics of the power cable, it is connected directly to the power lines (6) without disconnecting them (Fig. 1).

Another possible option for connecting the substation power cable to the power transmission line is shown in Fig. 2, when the connection is made through the cells of the open-pit mine installation (7), which includes a switch and relay protection for the line, to the overhead power transmission line.

In addition, the substation is designed with the possibility of connection via a cable (4) to a load (8).

The invention is used as follows.

The high-voltage power cable (4) is used to lay the cable line by unwinding the high-voltage cable from the reel (5) to the ground, while simultaneously transporting the substation to the deployment site. Directly at the substation installation site, the cable line is connected via the high-voltage switchgear (2) by connecting it to the high-voltage terminals of the 10(6)/0.4 kV transformer (1). The low-voltage switchgear (3) is connected to the low-voltage terminals of the transformer (1) via a cable line. The required load (8) is then connected via the power cable (4), and power is supplied to consumers.

The automatic transfer switch operates in conjunction with diesel generator sets. If connecting to diesel generator sets is impossible, the automatic transfer switch can be disabled by personnel.

If it is necessary to connect to an electrical network with a nominal voltage of 6 kV, personnel switch the device in the low-voltage switchgear (3) to the mode of transferring single-phase consumers to line voltage for the normal functioning of electrical equipment.

The device is a system of magnetic starters in a single housing design, connecting the neutral wires of the low-voltage distribution device cells to the phase wires A, B and C in such a way that single-phase consumers are supplied with the corresponding line voltage (for example, consumers connected to the phase wire A and the neutral wire, when putting the device into operation, will be connected to the difference in phase voltages A and B).

An electricity meter located at the input to a low-voltage switchgear is used to record the amount of electricity consumed.

After the loss of the need for power supply, the mobile substation can be shut down in the reverse order after it is disconnected from the stationary electrical network, for example, an overhead power line.

Fig. 3 shows an example of the invention's implementation. The data presented were obtained during experimental testing of the substation.

The modular mobile transformer substation is mounted on a 3500x1500 mm vehicle trailer with a total weight of 1200 kg and consists of:

high-voltage cell RU-10 kV;

voltage transformer 10/0.4 kV with a capacity from 25 to 250 kVA;

0.4 kV power distribution board;

fast unwinding devices with cable drums;

Expert Class MIP-10 kV cable 1x2.5 sq.mm. with a total length of 3000 m;

prefabricated supports 6 m high – 20 pcs. – grounding kit;

sets of connecting and end couplings;

live connection kit.

Compared to known analogues from the state of the art, the proposed mobile transformer substation with a quickly erected electrical network was installed in hard-to-reach places at a distance of more than 1 km from the connection point.

The following results were recorded:

connection of the kit under voltage of 10/6/0.4 kV;

electrical connected power from 25 kW to 250 kW;

the installation speed of a 10/6 kV network by a team of 4-6 people using a combined method is 5-10 km per day;

transmission of 250 kW power at 10 kV voltage – over a distance of up to 5 km;

transmission of 25 kW power at 10 kV voltage – over a distance of up to 50 km.

The power cable was attached to the power transmission line without disconnecting it using a PRVT-10 kV fuse-disconnector, to tree trunks using support clamps, across water obstacles using floats, and in other places prefabricated supports of H=6000 were used.

Thus, the proposed design of a mobile transformer substation with a quickly erected electrical network ensures the organization of electricity supply to consumers, while the following issues are comprehensively resolved simultaneously: efficiency (without disconnecting the power line), connection of the mobile transformer substation directly to the high-voltage line, laying of the cable line in hard-to-reach places, the possibility of connection to a stationary electrical network with different nominal voltage classes of 10 kV or 6 kV, eliminating the need to organize a sanitary zone, and the ability to provide electricity to consumers at a distance of more than 1 km from the connection point.

Claims (6)

1. A mobile transformer substation with a quickly erected electrical network, including a wheeled transformer with high and low voltage switchgear, equipped with an electric energy meter and with an installed reel for winding a power cable, characterized in that it is equipped with a transformer with a rated voltage of 10 (6) / 0.4 kV with a three-rod steel core with primary and secondary windings of phases A, B and C and a power cable including a copper single-wire conductive core with a cross-section of 2.5 mm ² , having a face-centered crystal lattice with unidirectional metal grain sizes obtained by thermoplastic deformation, on top of which a silane-crosslinkable composition based on an electrical insulating material with the addition of an aqueous crosslinking catalyst is applied, on top of which a copper foil screen is located, connected to an overhead power line of 6-10 kV, wherein the cable through a higher voltage switchgear voltage is connected to the contact tips of the high-voltage inputs of the 10(6)/0.4 kV transformer, and the low-voltage switchgear is connected to the contact tips of the low-voltage inputs of the transformer. 2. A substation according to paragraph 1, characterized in that it is installed on a wheeled base with increased ground clearance and with the ability to connect to small-sized and highly mobile vehicles. 3. A substation according to paragraph 1, characterized in that an electric energy meter is located at the input to the low-voltage distribution device. 4. A substation according to paragraph 1, characterized in that the low-voltage distribution device is equipped with an automatic reserve input device. 5. A substation according to paragraph 1, characterized in that the low-voltage distribution device is equipped with a device for transferring single-phase consumers on the low-voltage side to line voltage when connected to a 6 kV network, as well as an automatic reserve input device connected in parallel. 6. A substation according to paragraph 1, characterized in that the power cable is connected to the load.