RU2720818C1 - Device for fault location of power transmission lines and communication lines - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: invention relates to power engineering, namely to means of detecting coordinates of faults of power transmission lines and communication, and can be used in systems for remote determination of damage point of high-voltage lines. Summary: device for determining point of damage to power transmission line and communication includes a generator of probing pulses connected to a receiver, a computing unit and a directional coupler, which are interconnected. Directional coupler and the computing unit are connected through a switchboard to a power line and a communication line. Device is additionally equipped with a compensation unit, the first input of which is connected to the output of the directional coupler, the second input - to the fourth output of the computing unit. Output of the compensation unit is connected to the first input of the receiver.

EFFECT: technical result is increase in the power transmission line and communication line damage detection distance while maintaining the distance measurement accuracy to the damage point.

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Description

The claimed invention relates to the field of energy, namely, to radar systems designed to detect and control the coordinates of damage to power lines / communications, and can be used in remote sensing systems for damage to high voltage lines (VL), mainly three-phase, with a large number of heterogeneities.

       From the prior art, a method is known in which probing pulses are fed into a line, which, being reflected from the places of damage and heterogeneities, enter a receiving and regulating device, then to a measuring device. The time interval between the probe pulse and the pulse reflected from the damage site is fixed. This time interval is proportional to the distance from the beginning of the line to the place of damage (G. Shalyt. Determination of places of damage in electric networks. - M .: Energoizdat, 1982, p. 188).

     This method does not take into account the attenuation of signals in the test line and, as a result, the implementation of the method gives a low sensitivity to damage with a large length of the test line.

A device is known that contains a probe pulse generator (PSI), an attachment filter (FP), a coupling capacitor (CS), an input device, a memory unit, an analog-to-digital converter (ADC), a microcomputer, a synchronization unit, while the attachment filter is connected to "Ground" and through a coupling capacitor connected to the test line, and also connected to the output of the probe pulse generator and to the analog input input device, the output of which is connected to the analog input of the analog-to-digital converter, and the output of the analog-to-digital converter is connected to the input of the microcomputer the outputs of which are connected to the input of the synchronization unit and to the input of the data recording of the memory unit. The outputs of the synchronization block are connected to the input of the probe pulse generator, to the input of the partial interval number selection of the memory block and to the synchronization input of the analog-to-digital converter. The output of the memory block is connected to the control input of the input device (patent No. 2654378 for the invention "Method for determining the location of damage to power lines with a large number of heterogeneities", filing date 05/24/2017, published 05/17/2018).

This invention has several disadvantages. In particular, this concerns the determination of the location of damage located near the device, as the signal from the tap itself and from incomplete damage come with the same delay. The device does not allow to identify the type of damage, because phase relations are not taken into account. In addition, there is no separation between the reflected and probing signals, as well as the allocation of the reflected signal, and for this reason “dead” zones appear near the device.

The closest technical solution to the claimed invention is a device for determining the location of damage to power lines and communications, containing a probe pulse generator, a computing unit, the first output of which is connected to the input of the generator, a receiver having two inputs and a second input connected to the second output of the generator, and the output is with the input of the computing unit, while the probe pulse generator has a memory unit, a digital-to-analog converter and a power amplifier, the input of the memory unit is the input of the generator, the output of the power amplifier is the first output of the generator, and the device further comprises a switch, a directional coupler and an information transfer unit moreover, the first output of the generator is connected to the input of the directional coupler, the second output of the generator is the output of the digital-to-analog converter connected to the second input of the receiver, the input / output of the coupler is connected to the input / output of the switch, and the output is connected to the first the receiver’s input, the switch input is connected to the second output of the computing unit, the third output computing unit is connected to the input of the information transmission unit, n switch outputs are connected to n wires of the power line (RF patent No. 2400765 for the invention “Method for determining the location of damage to power lines and communication and device for its implementation ", filing date 12/18/2008, published 09/27/2010).

The disadvantage of the prototype is, first of all, that the level of the signal reflected from the inhomogeneities of the signal line, including from the damage sites located at large distances, is much less than from the inhomogeneities located near the probe pulse generator, which does not allow to increase the probe power signals and, accordingly, the range of determining the location of damage.

The task to which the claimed invention is directed is to maintain the effective operability of the device with increasing signal attenuation during operation of the line in the case of adding solders (consumers), or changes in weather conditions (rain, fog, temperature, etc.), or various wear line elements, such as insulators, disconnectors, arresters, or increasing the length of the line itself.

This problem is solved by increasing the level of the probe signal at the output of the power amplifier with a constant dynamic range of the receiver.

The technical result to which the claimed invention is directed is to increase the range of determining the location of damage to power lines and communications while maintaining the accuracy of measuring the distance to the place of damage in any power lines, both homogeneous and heterogeneous, with an arbitrarily changing phase speed in different sections of the line.

 This result is achieved in that the device for determining the location of damage to the power line and communication, including a probe pulse generator connected to the receiver, the computing unit and the directional coupler, which are interconnected, while the directional coupler and the computing unit through the switch are connected to the transmission and communication line , according to the invention is additionally equipped with a compensation unit, the first input of which is connected to the output of the directional coupler, the second input is connected to the fourth output of the computing unit, and its output is connected to the first input of the receiver.

The invention proposed for protection is illustrated by drawings, where

FIG. 1 is a schematic diagram of a device for determining the location of damage to power lines and communications;

 FIG. 2 is a schematic diagram of a compensation unit.

FIG. 3 - a fragment of a two-wire line with one tap, the wave impedances of which are equal to w.

 The inventive device comprises a probe pulse generator 1, which includes a memory unit 2, a digital-to-analog converter (DAC) 3 and a power amplifier (PA) 4, as well as a directional coupler (BUT) 5, switch 6, differential signal receiver 7, computational unit 8 and information transfer unit 9 (Fig. 1).

In this case, the first output of the computing unit 8 is connected to the input of the generator 1. The signal receiver 7, having two inputs, is connected to the second output of the generator 1 by the second input and to the input of the computing unit 8. The input of the memory unit 2, which is a part of the probe pulse generator 1, is simultaneously the input of the generator itself, and the output of the power amplifier (PA) 4 is the first output of the probe signal generator. The directional coupler (BUT) 5, the input of which is connected to the first output of the generator 1, the switch 6, the input / output of which is connected to the input / output of the directional coupler 5, the input of the switch 6 is connected to the second output of the computing unit 8, the third output of which, in its the queue is connected to the input of the information transmission unit 9, as well as n outputs of the switch 6 are connected to n wires of the power transmission line and communication.

The device is additionally equipped with a compensation unit 10, the first input of which is connected to the output of the directional coupler 5, and the second input to the fourth output of the computing unit 8. The output of the compensation unit is connected to the first input of the signal receiver 7 (Fig. 2).

It is known that when the signal propagates from left to right along the line from the point of connection of the tap (consumers) to the line (Fig. 3), the signal is partially reflected, and partially propagates from bottom to top along the tap and from left to right along the line. In this case, the reflected signal propagates from right to left to the signal receiver, and its value with full coordination of the line and the soldering at the ends is determined based on the following relation

U neg / U fall = (w-0.5w) / (w + 0.5w) (1)

or

Urel = Uad / 3 (2), where

U neg - the magnitude of the reflected signal;

Uad is the magnitude of the incident wave;

w is the value of wave impedances.

In this case, the value of the transmitted signal is in correlation with the incident wave, as U pol = 0.61 U dec. (Fundamentals of radio engineering. A.A. Kharkevich. - 3rd ed., Sr. - M .: FIZMATLIT, 2007).

Thus, the transmitted wave decreases by 4.2 dB from the left to right, and the wave reflected from the damage when attenuating from right to left decays by exactly the same amount, i.e. with the passage of one tap, the wave reflected from the damage at the receiver input decreases by 8.4 dB. Consequently, the total signal attenuation at N tap-offs will be N times greater than from one.

In the technical solution proposed for protection, a compensation unit 10 is additionally introduced, which is connected through the first input to the output of the directional coupler and the second input to the fourth output of computing unit 8. Establishing an additional relationship between the fourth output of computing unit 8 and the second input of the compensation unit allows you to subtract all from the reflected signal negative components - interference arising from line inhomogeneities located to the left of the damage site and to reduce the level of interference at the first input of receiver 7, and also to form a signal to a value that does not cause its overload.

 The compensation unit 10 includes a memory unit 11, the first input of which is connected to an analog-to-digital converter (ADC) 12, and the output to a digital-to-analog converter (DAC) 13, while both converters are connected respectively to the first and second inputs of the differential amplifier 14, wherein the ADC is connected to the amplifier through an attenuator (ATT) 15, which serves to attenuate and smoothly reduce the intensity of electrical vibrations.

The implementation of the aforementioned additional connection of the fourth output of the computing unit with the second input of the compensation unit ensures that the reflected signal coming from the damaged section of the line and the signal stored in the memory of the compensation unit are compared to the first input of the compensation unit and to the second input. Due to this, signals reflected from inhomogeneities located between the power amplifier and the damage are not received at the input of the receiver, which can significantly increase the power of the probing signals and, accordingly, the determined distance from the generator to the place of damage.

The implementation of the invention.

 Pre-calibrate the device. To do this, an array of reflected signals — reference images received from an intact high-voltage line (VL) — is inserted into the memory of the computing unit 8 and the memory unit 11 of the compensation unit 10.

When passing from all the solders (inhomogeneities) of the reflected signals in the compensation unit, the received reflected signals are subtracted from the reference reflected signals stored in the memory unit of the compensation unit.

In the absence of damage to the overhead line, the difference signals will be equal to zero. Any damage in the overhead line, for example, a short circuit of any phase to ground, a wire break, a short circuit of two phases, etc. leads to the appearance of a difference signal.

It is known that the level of the reflected signal from damage at long ranges is less than from inhomogeneities located near the generator directing the probe pulses. To correct this drawback, it is necessary to increase the power of the probing signals, which will increase the range of determining the location of the damage.

  Amplified sounding pulses with a given time-frequency modulation are sent to the power line and communication from the generator 1. The reflected signal from the output of the directional coupler 5 is fed to the first input of the compensation unit 10, in which it simultaneously passes to the first input of the differential amplifier 14 and through the attenuator to an analog-to-digital converter (ADC) 12, where it is converted and then fed to the memory unit 11, where reference echoes corresponding to intact overhead lines are stored. In the absence of damage to the line, both signals: reference and reflected, cancel each other, i.e. the difference signal will be zero. In case of damage to the overhead line, the signal reflected from the line will differ from the reference signal of the undamaged line, and a “useful signal” will be detected, i.e. reflected from the real object against the background of all kinds of interference, which will pass to the differential receiver 7. As a result of the analysis of the difference signal coming from the receiver to the computing unit 8, a decision is made about the presence or absence of damage in the overhead line.

From the receiver 7, the signal passes to the input of the computing unit 8, which may contain a complex of electronic components, including a microcomputer with a data address, control bus, processor module, keyboard control device, memory module (not shown in the drawing). In the computing unit, the received difference signal is processed, after which it passes through the third output of the computing unit to the information transfer unit, in which a parametric sounding signal is generated. At the same time, the reflected signal from the computing unit passes to the DAC 3 for processing and then enters the overhead line in the form of a new sounding signal and passes through the output 2 of the generator to the second input of the receiver 7, in which the reflected signal is demodulated.

It is known that the pulse power of the probing signal determines the range, while the power of the probing signal is related to the signal power at the output of the transmitting device.

According to the claimed invention, all signals reflected from inhomogeneities located between the probe pulse generator and the damage remain unchanged and are compensated, i.e. the difference signal will be zero. And at the first input of the receiver, exactly that signal will be received, which contains information received from the place of damage, and at which the specified quality of detection is ensured, because the signal is cleaned of noise and signals reflected from the closest damage to the inhomogeneities in the line. This allows you to accurately determine the coordinates of the place of damage in any power lines, both homogeneous and inhomogeneous with an arbitrarily changing phase speed in different parts of the line, and increase the range at which such damage is determined.

Claims (1)

A device for determining the location of damage to a power line and communication, including a probe pulse generator connected to a receiver, a computing unit and a directional coupler, which are interconnected, while a directional coupler and a computing unit through a switch are connected to a power and communication line, characterized in that equipped with a compensation unit, the first input of which is connected to the output of the directional coupler, the second input - with the fourth output of the computing unit, and its output is connected to the first input of the receiver.

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