RU41680U1 - DEVICE FOR DETERMINING THE DISTANCE FROM THE SUBSTATION TO THE PLACE OF VIOLATION OF THE INSULATION OF THE ELECTRIC TRANSMISSION WIRES - Google Patents

Abstract

The utility model relates to electrical engineering, in particular to the electrification of railways. The essence of the utility model is as follows: in a known device for determining the distance to the place of a single-phase earth fault, consisting of a substation grounding conductor, an electrical energy source, a switching device and an overhead line phase wire, an inductance is additionally connected with a jump detection unit connected in parallel to it voltage. The proposed device allows you to determine the location of the circuit directly from the power line of the substation, which reduces the time to troubleshoot.

Description

The utility model relates to electrical engineering, in particular to the electrification of railways, and can be used to determine the distance to the point of closure of the overhead line (OHL) wire to the ground caused by a wire break or an insulation breakdown on the support. The model can be applied on the contact network of the main railways, in the “two wire rails” (DPR) systems, in the automatic blocking overhead lines.

Known technical solutions for determining the distance to the ground fault in overhead power lines (L-1), the principle of operation of which is based on the analysis of the input resistance "substation bus - ground", which is based on the results of experiments on the supply section of the substation.

However, due to the fact that the resistance to spreading of wires that have fallen to the ground, the resistance of the support and its foundation part are probabilistic in nature and vary within wide enough ranges, the reliability of determining the distance from the input resistance measured in an accident is small.

The device described in (L-2) is based on the fact that the distance to the place of insulation violation is located by the current distribution in two OHL wires (one of which is a wire that is closed to the ground, and the other is a wire of a healthy phase), connected to the beginning of the line to the source of electricity and shorted to each other at the end of the line. In this case, the result obtained does not depend on the resistance to spreading wire-to-ground, the resistance of the supports.

This device is the closest in technical essence to the proposed device. It is taken as a prototype.

The known prototype device (L-2) consists of a substation earthing switch connected in series, a power source and a switching device, to which a phase wire with damaged insulation is connected and a wire of working phase connected to it at the beginning and end of the line. The current in each wire is measured by a corresponding current sensor. The distance to the ground fault is determined by the ratio of these two currents.

A disadvantage of the known device is that when using it, it is required to short-circuit two phase wires between themselves at the beginning and at the end of the line. This necessitates the movement of the work crew along the line, which reduces labor productivity.

Another disadvantage of the device is its failure in the event of a circuit caused by a wire break with a subsequent fall to the ground.

This is due to the fact that one of the currents, the value of which must be known to determine the distance to the accident site, becomes equal to zero.

Thus, the scope of the prototype device is limited (it can only be used if insulation is broken on the support).

The technical result of the proposed utility model is to increase the reliability of determining the distance from the substation to the place

single-phase earth fault, as well as increasing labor productivity when searching for a place of damage.

The essence of the utility model is as follows.

In a known device for determining the distance to the place of a single-phase earth fault, consisting of a substation grounding conductor, a source of electrical energy, a switching device and a phase wire of an overhead line connected in series, an inductance with a voltage surge detection unit connected in parallel is also included.

The claimed utility model is illustrated by drawings.

So, figure 1 shows the calculated electrical equivalent circuit, explaining the principle of determining the distance to the location of the damaged phase wire implemented in the utility model. The following notation is used:

E, Rvn - emf and internal resistance to constant sources of electricity,

L - upstream inductance, the value of which is known,

Lo, Ro - the known inductance of 1 km of the wire-to-ground loop, GN / km, and the ohmic resistance of the wire, Ohm / km,

l is the distance from the substation to the place of a single-phase circuit of the wire to the ground, km,

Rp is the resistance of the support or the resistance to spreading of the wire lying on the ground, Ohm,

t is the point in time.

It is known that the resistance to spreading of wires that have fallen to the ground, the resistance of the support, including its foundation part, and the resistance of the substation earthing conductor at low (less than 1 kHz) frequencies are purely active.

Based on the limit theorem of the operator calculus (L-3), the magnitude of the voltage across the inductance L, measured at time

t = 0 + (the moment immediately following switching) does not depend on the active resistances included in the electric circuit shown in Fig. 1 (including the resistance Rp random in magnitude) and is equal to

From formula (1) it follows that for known values of E, L, L ₀ and U _ab (0+), the distance l to the point of fault to the ground is found from relation (2):

Figure 2 presents a schematic diagram of a device that implements the principle of determining the distance to the place of damage to the insulation of the phase wire of the overhead line as stated above.

The device consists of 1 - a wire of a damaged phase, 2 - a switching device, 3 - a constant source of electrical energy, 4 - a substation earthing switch, 5 - a given value inductance and 6 - a unit for determining the voltage jump on the inductance.

The device operates as follows:

If the insulation of the phase conductor of the overhead line is violated, the corresponding phase is switched off by the switching device (switch) installed at the substation with fixation of the damaged phase (L-4). After that, at the substation, to the phase wire 1, the damaged phase, through the switching device 2 are connected a series-connected constant source of electrical energy 3, connected with its negative pole to the ground electrode of the substation 4, and a well-known inductance 5, in parallel with which a voltage surge detection unit 6 is connected.

When the switching device 2 is activated, a constant voltage from the source 3 is supplied to the damaged phase 1, as a result of which a voltage jump appears on the inductance 5, which is fixed

block 6. Further, by the formula (2) determine the distance to the place of violation of insulation of overhead lines.

The proposed device allows you to determine the location of the circuit directly from the power line of the substation, which reduces the time to troubleshoot.

Since in the considered circuit of Fig. 1 the magnitude of the voltage jump to which the device reacts does not depend on the active resistances included in the circuit, including the resistance Rp, the device works equally reliably in the event of a wire break and falling to the ground, and case of breakdown of insulation on the support.

Sources of information taken into account when compiling the description.

1. Rüdenberg. Transients in electric power systems. M .: Publishing House of Foreign Literature. - 1955. - 709 s

2. Pupynin V.N., Nguyen V.Kh., Patent No. 2096795 for the invention "A device for determining the distance to the place of a single-phase earth fault in 6-35 kV networks of electrical systems with isolated or compensated neutral" (prototype)

3. Atabekov G.I., Timofeev A.B., Khukhrikov S.S. Theoretical foundations of electrical engineering. Part 2. M .: Energy. - 1970. - 232 p.

4. Kosarev B.I. Electrical safety in traction AC networks. M .: Transport. - 1989. - 200 p.

Claims (1)

A device for determining the distance from the substation to the place of violation of the insulation of the wires of the power line, consisting of a substation grounding conductor, an electric energy source, a switching device and a phase wire of an overhead power line connected in series, characterized in that a well-known device is connected between the output terminal of the electric power source and the input terminal of the switching device value of inductance with a voltage jump detection unit connected in parallel to it.