RU2390438C1 - Method to reduce inductive influence of electric traction circuits on communication line - Google Patents

Abstract

FIELD: transport.

SUBSTANCE: method relates to electrified railroads and can be used to reduce inductive effects of AL electric traction circuits on wire communication lines. To this end, additional wire is laid along railway. Said wire is divided in equal length intervals into sections each comprising capacitance connected therein and arranged successively, one after the other. Beginning of all sections, starting from the first one, is connected to separate earth electrode, while sections ends are connected to rail circuit. Quantity and length of sections are defined subject to minimum level of interference induced in adjoining communication line, while capacitance parametres are defined subject to possibility to rule out or drastically reduce harmonics current flows in every section.

EFFECT: increased compensation current in additional wire and reduced power losses in traction circuit.

1 cl, 1 dwg

Description

The method relates to the field of electrified railways and can be used to reduce the electromagnetic effect of electrified railways on adjacent wired communication lines.

The known method (1) to reduce the inductive effect of electric traction AC networks on wire communication channels, in which a compensating current is formed using suction transformers in the return wire located along the traction network, the first harmonic of which is phase-shifted relative to the first harmonic of the traction current, approximately equal to 160 e. hail. The result of the addition of electromagnetic fields created by traction and compensating currents is a decrease in influence from the traction network.

The known method has the following disadvantages.

1. The total inductive effect caused by the current of the return wire and the current of the rail circuit is much larger than the inductive effect due to the current in the contact network of this path. Thus, there is an overcompensation of the inductive main influence.

2. The need for sequential inclusion of the primary windings of transformers in the contact network causes an increase in the total resistance of the latter, which in turn leads to an increase in energy losses.

3. The limitation on the estimated power of the suction transformers does not allow increasing the currents of the traction load, which reduces the efficiency of solving the problem of traction power supply.

4. The phase shift between the harmonics of the traction current and the corresponding harmonics of the compensation current fluctuates, as the calculations show, within 157-178 e. hail. (in contrast to the required 180), which also reduces the efficiency of using the method.

5. The described compensation method is not applicable on DC roads.

There is a known (2) method for reducing the inductive effect of electric traction networks on a communication line, in which sections equipped with suction transformers and a return wire alternate with sections without suction transformers and a return wire.

Used in this invention, the method is closest to the claimed technical essence and the achieved positive effect, therefore, it is selected as a prototype.

The interference compensation method adopted as a prototype has the same disadvantages as the analog method. In addition, in areas not equipped with suction transformers and a return wire, the degree of reduction of electromagnetic interference is generally small.

The problem solved by the invention is to increase the efficiency of reducing the inductive effect of electric traction networks on wire communication channels by increasing the value of the compensating current in the return (additional) wire to the maximum possible, in the case of the formation of the compensating current in the additional wire without an additional emf source, while reducing costs the protection of communication lines, reducing voltage and energy losses in the traction network and expanding the scope of the compensation method.

This is achieved by the fact that a capacitance is included in an additional wire located along the railroad track and, at equal intervals of its length, it (the wire) is partitioned, i.e. divided into sections that are arranged sequentially - one after another. The beginnings of all sections, beginning with the first, are grounded to individual earthing switches, and the ends are connected to the rail circuit. The essence of the method is determined by the following. As you know, already a few kilometers from the substation, all traction current flows in the ground. Thus, only eddy currents induced by the traction current are present in the rail and in the auxiliary wire. Consequently, through electromagnetic coupling in a system formed by a traction network, an additional wire, a rail network and ground, three circuits are formed: a contact wire - a rail, a contact wire - an additional wire, and a rail - an additional wire. To be more precise, there are four circuits, because there is a reverse effect of the additional wire on the rail. Based on these considerations, the shielding effect on an adjacent communication line is determined by summing the shielding effect on the side of the "contact wire - rail" circuit and the "contact wire - additional wire" circuit and is weakened by the electromagnetic interaction between the "additional wire - rail" and "rail - additional the wire". If, therefore, we exclude the influence on the process of compensating electromagnetic interference, the influence of the “additional wire - rail” and “rail - additional wire” circuits, which reduce the compensation current flowing in the shielding (return) wire, i.e. If the electromagnetic connection between the rail and the auxiliary wire is replaced by the direct connection of the rail circuit with the auxiliary wire, then the latter can achieve the maximum compensation current. The physics of the process occurring during the implementation of the proposed method can be explained as follows. As is known, for example, from (3), the vector of the current induced in the auxiliary wire lags behind its emf of the induction induced in it by the traction influencing current, by an angle depending on the ratio of the inductive and active resistances of the additional wire – ground circuit. Thus, in the case of an increase in the inductive resistance of the mentioned circuit or, which is the same (with respect to the achieved effect), a decrease in its active resistance, the angle between the vectors induced in the additional wire of the induction emf and the current created by this emf can be brought to a value at which the angle between the induction emf vector induced in the adjacent communication line by the current flowing in the auxiliary wire and the induction emf vector induced in the adjacent communication line by the influence current flowing in the traction network to 180 degrees, which is equivalent to the minimum interference level or the maximum compensation effect. When implementing the proposed method, in the case of connecting an additional wire with a rail, the inductive coupling between the rail and the additional wire is converted into a parallel connection of these circuits. Thus, the total active resistance to the flow of the resulting current I _p + I _{e is} significantly reduced. As for the inductances of the circuits, in their case there is an exchange of energy between the above circuits. The fraction of current induced in the additional wire, as shown by calculations and experiments, in this case increases from almost 39% to 85%. It should also be noted that longitudinal sectioning eliminates, if necessary, overcompensation both in places where current is present in the rail, and in the case of other circumstances. When implementing the proposed method of reducing the inductive effect, the number and length of sections is determined by the requirement for the level of reduction of the induced noise. In general, a section may be one. In addition to the above, the presence of capacitance in the sections of the shielding wire allows you to achieve the following effect. If you select the capacitance in such a way that its resistance is large enough for the first harmonic (50 Hz) and large for the harmonics of the third and fifth (150 Hz and 250 Hz) that are not involved in the formation of interference in the adjacent communication line (not having a psophometric effect), it is thus possible to reduce the current flowing in the shielding wire. As a result of this, the power consumed by the "shielding wire-ground" circuit from the traction network will decrease, i.e. the total energy consumption of the traction network will decrease.

The essence of the proposed method is illustrated in the drawing.

The following notation is introduced in the drawing:

1 - contact network;

2 - rail chain;

3 - an additional wire, divided into sections under the condition of minimum interference in an adjacent communication line, each of which includes a capacitance;

4 - adjacent communication line.

The method is as follows. An additional wire located along the railroad track is sectioned at regular intervals of its length, i.e. They are divided into sections that are arranged sequentially - one after another and in which they include a capacitance that provides a sufficiently large resistance to the first, third and fifth harmonics, which do not exert a psophometric effect on the adjacent communication line. The beginnings of all sections, starting from the first, are earthed to individual earthing switches, and the ends are connected to the rail circuit.

Thus, as a result of the sequence of actions forming the inventive method, by eliminating the influence on the formation of the compensating current in the additional wire, the influence of the "additional wire - rail" and "rail - additional wire" circuits by replacing the electromagnetic coupling between them by directly connecting the additional wire with a rail chain, as well as by eliminating the flow of harmonic components in the shielding wire that do not have a psophometric effect on the adjacent th link, the compensating current is increased to the maximum possible values in given conditions and with reduced loss in traction network.

INFORMATION SOURCES

1. A.S. USSR No. 2221752, Bull. No. 22, 07/17/1968, class B60m.

2. A.S. USSR No. 169556, Bull. No. 7.22.04.1965, class B61m, H02d, 1965.

3. K.G. Marquardt. Power supply of electric railways. - M .: Transport, 1965, from 432-438.

Claims (1)

A method of reducing the inductive effect of electric traction networks on a communication line, namely, that in an additional wire located in the zone of influence of the traction network on the channels of an adjacent communication line and grounded on one side, a spatially shifted compensating current is formed, characterized in that the additional wire is divided into sections, each of which includes a container, and which are arranged sequentially - one after another, and the beginning of all sections, starting from the first, are grounded to individual grounding conductors, and Dinh to the track circuit, and the number and length of the sections is determined by the condition of the minimum level of interference induced in an adjacent link, and the parameters of the containers is selected on the condition eliminate or significantly reduce the flow in each section of the harmonic currents, not providing psophometric impact to adjacent communication links.

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