RU2506676C2 - Device for symmetrical distribution of single-phase load between phases of three-phase network - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: application: in the field of electrical engineering. Device for symmetrical distribution of single-phase load between phases of three-phase network represents three-phase single- or multi-winding dividing transformer; at that each of secondary windings has additional turns independent from the main winding which are designed to compensate voltage drop in line and each consumer of the multi-winding dividing transformer is supplied from own or common (for single-winding dividing transformer) secondary winding, where line of each consumer is supplied from three in-series phase coils of the transformer, at that any two coils are connected in alignment while the third one is opposing connection.

EFFECT: increasing capacity of distributing electric grids, reliability of power supply and safety of single-phase consumers.

Description

The invention relates to the field of electrical engineering, in particular to the power supply of single-phase consumers from three-phase networks, including consumers of public utilities and can be used in three-phase three-, four- and five-wire distribution electric AC networks.

Until now, the only way to ensure symmetrical loading of three-phase three-four- and five-wire networks (three phases - zero and 3 phases zero and a protective conductor) of alternating current voltage up to 100.0 V and three-phase power transformers of the same voltage on the secondary winding with a uniform phase load, in the presence of single-phase consumers in the networks, the load is physically connected as even as possible (in terms of power consumption) to the phases of the three-phase network (symmetrical distribution of the load in phases) [Kir Eva EA Power supply and electrical equipment of workshops of industrial enterprises // - M.: Knorus. 2011 .-- 368 p. (P.139)].

This technique, however, does not provide constant (even approximate) load symmetry of either networks or power transformers, both because of the different power consumption of single-phase consumers, and because of the mismatch of their load graphs in phases, which entails :

1 - reduction in the capacity of power networks and transformers;

2 - increased losses in the network due to the flow of current through the neutral wire;

3 - reducing the reliability of power supply to consumers due to the possible overload of one of the phases and its shutdown protection.

The objective of the invention is to increase: the capacity of distribution electric networks, the reliability of power supply and the safety of single-phase consumers of electric current.

The task is achieved by a device for the symmetric distribution of a single-phase load across the phases of a three-phase network, which is a three-phase isolation single or multi-winding (in the secondary circuit) consumer transformer, moreover, each of the secondary windings has additional turns independent of the main winding, designed to compensate for the voltage drop on the line, and each of the consumers of a multi-winding isolation transformer is powered from its own or from a common one (for a single-winding transform torus) of secondary windings, wherein each customer line is powered by a three phase coils of the transformer connected in series, any two of which are included in unison, and the third - the counter.

New significant features:

1 - the inclusion of three phase coils of each secondary winding of the transformer in series, any two of which are connected in concert, and the third counter-allows you to get a single-phase alternating voltage.

2 - feeding a single-phase winding of the line simultaneously from three phases allows you to evenly distribute the load in phases and provides absolute symmetry of the load of the line and the transformer of the substation.

3 - symmetrical load of the line and transformer of the substation allows to increase the throughput of the electric network;

4 - the presence in each of the secondary windings of additional turns independent of the main windings allows you to get 3 levels of voltage regulation up and, if necessary, 3 - down, which improves the quality of power supply;

5 - power supply of a single-phase winding simultaneously from three phases allows the voltage supply to any of the phases to ensure power supply from the remaining two phases connected opposite to each other at the level of 0.965 rated voltage of the network with the number of additional turns constituting 10% of the number of turns of the winding, which increases quality and reliability of power supply;

6 - power supply of each of the consumers from its winding of a multi-winding transformer completely eliminates galvanic communication with other power consumers, improves the quality and safety of power supply;

7 - power supply to the consumer through an isolation transformer provides galvanic isolation of the consumer from an external powerful network and increases the security of power supply.

The listed set of features provides a technical result in all cases to which the requested amount of legal protection applies.

The technical result is ensured by the inclusion of three phase coils of each secondary winding of the proposed device in series, any two coils of which are connected in concert, and the third is counter, which allows you to get a two-wire single-phase AC line, the load of which is evenly distributed across the three phases of the supply network, providing a symmetrical load line and supply transformer, regardless of the presence or absence of any single-phase load.

The lack of symmetry of the secondary voltages of the transformer substation adversely affects consumers. With three-phase squirrel-cage induction motors, when they are supplied with an asymmetrical voltage, the power decreases, in incandescent lamps, when powered by an increased voltage, the service life is sharply reduced, and when powered by a reduced voltage, the light output decreases significantly. An asymmetric load on a transformer causes overloading of its individual windings, saturation of the magnetic circuit and an increase in phase voltage.

Symmetric loading of the line and transformer of the substation allows increasing the throughput of the electric network.

The presence in each of the secondary windings of additional turns independent of the main windings allows you to get 3 voltage regulation steps up and 3 - down and allows you to maintain the voltage at the output terminals of the transformer within the acceptable limits in steps, or smoothly (with the use of additional stepless voltage regulation devices), which will ensure high power supply quality of a single-phase consumer.

Multiphase supply of a single-phase consumer at the same time from three phases allows the voltage of any phase to be switched by switching windings and additional turns to provide electric power to the single-phase consumer from the remaining two phases (with a uniform load of the latter) at a level not lower than 0.9 of the rated mains voltage, which improves the quality and reliability of power supply.

The power supply of each consumer or group of consumers from its own (separate) winding of a multi-winding transformer fully provides galvanic isolation from other consumers (or from other groups of consumers), and from a powerful external network, improves the quality and safety of power supply to single-phase power consumers, eliminating the influence of one consumer on others and vice versa.

Any asymmetry in the network equipped with the proposed devices means emergency operation, which will speed up the troubleshooting and helps to increase the reliability of power supply.

Claims (1)

A device for symmetric distribution of a single-phase load across the phases of a three-phase network, which is a three-phase isolation single or multi-winding (in the secondary circuit) consumer transformer, characterized in that each of the secondary windings has additional turns independent of the main winding, designed to compensate for the voltage drop across lines, and each of the consumers of a multi-winding isolation transformer is powered from its own or from a common (for a single-winding three-phase transformer) in orichnoy winding, wherein each customer line is powered by a three phase transformer coils connected in series, any two of which are included in unison, and the third - the counter.