RU151805U1 - DEVICE FOR TAKING A SMALL POWER FROM A HIGH VOLTAGE NETWORK - Google Patents

Abstract

A power take-off device from a high-voltage network containing a high-voltage capacitor, a low-voltage capacitor, a transformer, a matching reactor, characterized in that the high-voltage capacitor and the primary winding of the transformer are connected in series to the high-voltage network, the matching reactor is connected in series to the load, and the low-voltage capacitor is connected directly to the load.

Description

The utility model relates to the field of electrical engineering, in particular to electrical equipment for selecting small electric power from a high-voltage network, and converting it into low-voltage alternating current power.

A device for converting high voltage alternating current to low voltage alternating current is commonly known as an electromagnetic transformer, the description of which can be found, for example, in the following sources:

1. A.E. Alekseev. The design of electrical machines: a training manual for energy and electrical universities and faculties. - M. - L .: Gosenergoizdat, 1958

2. Vazhnov A.I. Electric cars. - L.: “Energy”, 1968.

3. Voldek A.I. Electric cars. - L .: "Energy", 1978

4. Katzman Μ.M. Electric cars. - M.: "Higher School", 2000

5. Ivanov-Smolensky A.V. Electric machines: a textbook for universities, in 2 volumes - M. ": Publishing House" MPEI "(Moscow Power Engineering Institute), 2006

The main disadvantage of an electromagnetic transformer designed to select a small power from a high-voltage network is the complex design of high-voltage insulation, and therefore the increased dimensions, weight and cost, compared with a low-voltage transformer. Currently, transformers for the selection of small power (up to 10 kW) from a network of a voltage class of 35 kV and its conversion to AC power of 220 V are not produced in series due to economic inexpediency.

A device consisting of a capacitive voltage divider and an electromagnetic transformer is also used to select low power from a high-voltage network and convert it to low-voltage AC power, they are also called capacitive voltage transformers, which are known, for example, from the following sources:

6. Usov S.V., Mikhalev B.N., Chernovets A.K. and other electrical part of power plants / under. Ed. Usova S.V. - L .: "Energoatomizdat", 1987

7. Dorokhin E.G., Dorokhin T.N. Autorecloser circuits in electrical networks: the use of capacitive voltage selection. Practical Guide. - M.: Publishing House NTs ENAS, 2002

8. The catalog of voltage measuring transformers of the ABB company “ABB - Buyer's Guide”, published on the Internet at: http://www.energopromis.by/img/file/ Measuring transformers_20 transformer_service_00%.pdf

Catalog of capacitive voltage transformers of the Croatian company KONCAR “VCU. Capacitive voltage transformers from 110 to 750 kV ”, published on the Internet at: http://www.koncar-mjt.hr/dolmenti/VCU%20brochure%20-%20Russian.pdf

The main disadvantage of capacitive voltage transformers is the presence of an expensive high-voltage capacitor, performed at high voltage with its significant capacity, which leads to a complication of the design, an increase in weight and dimensions.

Also known devices for the selection of low power from a high voltage network, using the induced magnetic field from a flowing alternating current, for example, from the following sources:

Patent of the Russian Federation for invention No. RU 2414034 “Secondary power source with power take-off from phase-wire current”.

Patent of the Russian Federation for invention No. RU 2483409 “Secondary power source with power take-off from a phase wire of a high-voltage power line of industrial frequency”.

Patent of the Russian Federation No. RU 2414035 “Power take-off system from the currents of a three-phase transmission line of high voltage”.

Patent of the Russian Federation No. RU 2496204 “Secondary uninterruptible power supply with power take-off from phase-wire current”.

The lack of devices for low-power selection from a high-voltage network, using the induced magnetic field from the flowing current - in the presence of voltage, but at a certain minimum current value in the network, power take-off becomes impossible.

Also known are devices with power take-off from a high-voltage network from induced voltage at the electrodes, from an acting electrostatic field, for example, from the following sources:

Patent of the Russian Federation for invention No. RU 2488931 “Secondary power source with power take-off from a phase wire of a high voltage power transmission line”.

The disadvantage of this device is the significant dimensions to obtain even a small selectable power.

The closest in technical essence to the patented device should be considered the device described in sources 6, 7, 8 and 9, and consisting of a capacitive voltage divider and an electromagnetic transformer.

Simplified diagram of a device for selecting low power from a high voltage network, consisting of a capacitive voltage divider and an electromagnetic transformer, is shown in figure 1. The device contains:

- Capacitive voltage divider, consisting of capacitors C1 and C2;

- Matching reactor LR connected to the midpoint of the voltage divider;

- An electromagnetic transformer T, the primary winding connected to the matching reactor RL and ground potential, and the secondary winding to the load of consumers Rн.

The device operates as follows. When a high voltage is applied to the capacitor divider, the voltage across the capacitors C1 and c2 will be divided inversely in proportion to the capacitance of the capacitors C1 and C2, i.e., a much smaller part of the voltage of the high-voltage network will be released on the capacitor C2, which has a significantly larger capacitance. The low voltage removed from the capacitor C2 is supplied to the electromagnetic transformer T through a matching reactor LR. The matching reactor LR is designed to coordinate the characteristics of a capacitive divider and electromagnetic transformer T. An additional voltage reduction occurs at electromagnetic transformer T to a level that can be supplied to the load of consumers Rн.

This design is currently used to build capacitive voltage transformers of class 35 kV and higher. The capacitor from which the voltage is removed for an electromagnetic transformer has a capacity of 40 to 70 nF in serial samples at a nominal voltage of 10 to 12 kV. The maximum power removed from serial capacitive transformers is 0.6 ... 1.2 kW.

A disadvantage of the known device is the high cost of the capacitor C2, which at a high rated voltage must have a significant capacity. An additional constructive problem is the output between the capacitors C1 and C2, and the matching reactor installed in its circuit - they require high-voltage isolation, both from the network potential and from the ground potential. All these factors complicate the device, increase its dimensions and weight.

A useful model solves the problem of creating a device for the selection of low power from a high voltage network, devoid of the above disadvantages.

The technical result that is achieved by the utility model is to simplify the design and reduce the size and weight of the device.

This is achieved by the fact that in a device for selecting low power from a high voltage network, a capacitor of a larger capacity and a matching reactor are transferred from the primary winding of the electromagnetic transformer to the secondary winding circuit, with appropriate selection of the capacitor and inductance of the matching reactor, taking into account the transformation coefficient of the electromagnetic transformer. In this case, the capacitor installed in the secondary circuit of the electromagnetic transformer, although it will have an even larger capacity, but due to the low rated voltage, will have smaller dimensions and mass than a high voltage capacitor. In this case, high-voltage isolation of the middle terminal of the capacitive divider and matching reactor is not needed at all, which also simplifies the design and reduces its dimensions and weight.

The utility model is illustrated by the drawing, where figure 2 shows a sketch of a patentable device.

A device for selecting low power from a high voltage network consists of:

- High-voltage capacitor of small capacity C1;

- electromagnetic transformer T;

- Matching reactor LR;

A low-voltage capacitor C2 connected directly to the load of power consumers Rн.

A device for selecting low power from a high voltage network operates as follows. The high-voltage capacitor C1 and the primary winding of the electromagnetic transformer T, connected in series to the high-voltage network, form a current circuit through which an alternating current flows, the value of which is set by the capacitance of the capacitor C1. An electromagnetic transformer in this case acts as a current transformer. A voltage is induced on the secondary side of the electromagnetic transformer, which causes a current to appear. If there is no consumer load Rн, then the current is closed on through the matching reactor LR to capacitor C2. If the load of consumers Rн is switched on, then the current closes both to the capacitor C2 and to the load of consumers Rн. In order to ensure that the voltage at the load of consumers Rн does not change when the load value changes, the parameters of the matching reactor LR must be matched to the electrical parameters of the electromagnetic transformer T and capacitor C2.

Thus, a device for the selection of low power from a high-voltage network has been created, which has a simpler design, lower weight and dimensions compared to existing analogues.

Claims (1)

A power take-off device from a high-voltage network containing a high-voltage capacitor, a low-voltage capacitor, a transformer, a matching reactor, characterized in that the high-voltage capacitor and the primary winding of the transformer are connected in series to the high-voltage network, the matching reactor is connected in series to the load, and the low-voltage capacitor is connected directly to the load.

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