UA64142A - Method for determining the distance to the power line fault location - Google Patents

Abstract

The proposed method for determining the distance to the power line fault location consists in generating a reference and testing pulse sounding testing signal, transmitting the sounding signal over the power line, receiving the reflected testing signal, determining the difference of the phases of the sounding signal and the reflected testing signal, and calculating the distance to the power line fault location from the said phase difference. The measurements are performed at the different frequencies of the sounding signal.

Description

Description of the invention

The invention relates to the field of electronic measuring technology and can be used to determine the length of the electric transmission line to the places of damage or inhomogeneity.

The propagation of signals along long electrical lines has a wave character. Refraction and reflection of the wave occurs at the boundary between the two media. The same phenomenon occurs when defects occur in the line - violations of the core, insulation (short circuits, leaks, etc.). Thanks to reflection, the place of occurrence of inhomogeneity is determined by the time of appearance of the reflected wave at the beginning of the line. 70 To measure the distance to damage or inhomogeneity in an electric line, it is known to use both pulse and phase distance measurement methods. Among the existing methods, the most accurate is the phase method |1), which is based on measuring the phase shift of the reflected signal relative to the input signal (|2, З). The phase method, providing high accuracy of phase measurement, allows you to accurately determine the distance to the damage.

The distance to the damage is determined by the formula:

Chr

Y- Z where x is the wavelength of the signal probing the line, m; t - phase shift between probing and reflected signals, rad;

At the same time, the phase method has disadvantages.

First, if the wavelength is less than the length of the investigated line, there is an ambiguity in the results of phase measurements, since existing phase meters measure phase shifts in the range from 0 to 360", that is, within one phase cycle (727 ). To eliminate the phase ambiguity of measurements, the well-known multi-scale phase method |4|, in which an increase in measurement accuracy is achieved by performing a number of measurements at different frequencies from a certain value of the lower frequency, which is determined from the condition of the unambiguity of the measurement, to the value of the upper frequency, at which the fractional part of the distance is measured.

Secondly, the method is designed for the presence of only one damage in the electric line. The presence of two or more damages leads to the appearance of several reflections in the line that have the same frequency and differ in phase and amplitude, which arrive at the beginning of the line as one signal with a certain total phase and amplitude that does not correspond to any of the reflections forming it . "IS

Third, the reflection phase also depends on the type of damage (short circuit, capacitive, decrease or increase in wave resistance). -

A known method of determining the length of the electric transmission line to the place of damage |5) is based on the modulation of a high-frequency test signal by a low-frequency harmonic signal, measurement

From the phase shift of the bypass modulating frequency after passing the modulated oscillations along the transmission line to the place of damage and back and determining the length of the electric transmission line with the ratio: im kt « where x is the length of the electric transmission line to the place of damage; -o s day phase shift of the bypass modeling frequency du, :z» -- speed of electromagnetic wave propagation along the transmission line.

The disadvantage of the modulation method is the low accuracy of the length measurement due to the ambiguity of the phase measurements, if the length of the electric transmission line exceeds the length of the electromagnetic wave of the contour 15 of the modulated signal: (22)

Their » and them - where they - the frequency of low-frequency modulation. и» 50 The pulse measurement method (6.7) is known, which is based on measuring the time between the input of the signal to the line and the reception of the reflection from the inhomogeneity. The distance to the ith inhomogeneity is defined as:

And ba" de " - speed of wave propagation in the line, m/s; 1st; - time of appearance of the ith reflection, s; in. The advantage of this method is the possibility of distinguishing the presence of almost any number of inhomogeneities in the line. A significant drawback of this method is the direct dependence of the resolving power on the frequency of the signal that probes the line with a simultaneous increase in the attenuation coefficient of the signal when passing through the line. 60 The task of the invention is to create such a method of determining distances to damage in an electric communication line, in which the introduction of new operations and obtaining additional measurement results would allow to increase the accuracy of measuring the length of the electric line to the places of damage.

The task is solved by the fact that in the method of determining the distances to the places of electric line damage, which includes dividing the test signal into reference and measurement, receiving the reflected signal, measuring the time of appearance of each reflection and measuring the phase differences between the received signal and the reference and calculating the lengths of the distances to inhomogeneities, according to the invention, the distances are calculated from the connections of the results of the pulse reflectometer with the results of measuring the phase of signals at different frequencies.

For research, a signal of the following type is used:

ZZ Od sovet).

When forming reflections from the signal probing the line, we receive the following signals: вх) sovi di

Echo) from owls in de) 70 s Svt Tu

Zk) Shk scoop dk where Ts1Sh",..Shk - amplitudes of reflected signals; fi. 02, -as 7 phase shifts between the reflected signals and the probing signal. /5 At the receiving end, at the point from which the probing signal is emitted, due to the passage of the reflected signals through one medium, the addition of the reflected signals will occur and their interference will be observed. As a result, we will get a total signal of the form:

Zk 5 nka on Z - sovi no) And the cathedral O.O - as sovi nfk)- Shk sovi fi k-

After simple trigonometric transformations, an expression for the total signal can be obtained:

Kk Kk vy - sovi In M sovi -viev tsu, vol

Kk-i Kk-i « dec AK - amplitudes of the cosine and sine components of the total signal, respectively.

Uh sokov Uh ziperk) k-y k-y

The received signal consists of sine and cosine components. The phase and amplitude of the total signal Ge can be expressed as follows:

Kk in

Uh sokov "- and - K-y

Cher KE chI zip 2 sfe) ' (Se) k-i

K I ik 2

Ak - U zipbrko | i In the owl) « k-i k-i vi Y | - c de fu - the tangent of the phase shift angle of the total signal;

Ah is the amplitude of the total signal. . » Let's solve the system of equations with respect to the amplitude of the cosine component. For this, we will make the following transformations. Let's express the amplitude of the sine component of the total signal in terms of the amplitude of the cosine component and the tangent of the phase shift angle. Let's substitute the obtained expression into the second equation. We get: (o) Kk Kk

TU M sovi) - IOKrh U Shk vip, t- k-i Kk-i - Kk 2 Kk 2 135 70 AE- In vipirki | same In the owl | - k-y k-y

Ko) K : 2 - UM vip) o But y. to 29 From:

Kk

R"! Ah

UM Bipsoi - tvY-IU3NK-

Kk-i in fe

Analyzing the obtained expression, we can say the following. The value of the right-hand side of the expression depends on the 60 value of the amplitude of the total signal and its phase shift angle, which can be obtained as a result of measuring the amplitude and phase by classical methods. The left part of the expression is a sum of K terms, each of which depends on the amplitude and phase of the reflected signals. Amplitudes depend on the attenuation of signals in the environment and the nature of reflection and absorption of energy by objects. Phases depend only on distances to objects.

Additional measurement information can be obtained by generating probing signals at multiple frequencies, for example 215.35, 2Ky, . The number of necessary frequencies is equal to 2K, it is chosen from the condition of the unique solution of the system of equations, because we get K unknown phases of reflected signals and K unknown amplitudes of the same signals.

Repeating all the above mathematical calculations, assuming that Tsu-Shka is... Chic for the segment

Frequency response of the line, which is linear, the following system of trigonometric equations can be obtained:

Kk

In mk vipiri - --k.

K- "Z sho r

K

70 UM zipifki - --E

Kk Myths

Kk

TU Mk vip - AJ. тв Тв Cho ruk de dk - phase shift for K-th inhomogeneity, determined by the pulse reflectometer method;

Shk - the amplitude of the reflected signal from the K-th inhomogeneity;

Ap" yap 7 amplitude and phase, determined by the method of phase meters. Solving this part of the problem is possible by using the results of pulse reflectometry. The distance 4 is determined from the reflectogram, from which it is possible to determine a separate phase dk t.c

Fk o- -»z where x is the wavelength.

Knowing the relative levels of amplitudes from the reflectogram, it becomes possible to determine the reflection coefficients of each "inhomogeneity" and, accordingly, the real amplitudes of Ck.

IR distances measured by the impulse method are approximate values, the error of which determination is determined by the impulse method. Using more accurate values of phase measurements (Ах, из) with the help of EM 3о of the proposed system of equations, the distances of the SC are determined with greater accuracy than in the basic pulse "Ж method. "--

The use of the proposed system of equations makes it possible to increase the accuracy of determining distances to inhomogeneities in the communication line while simultaneously preserving the resolution of the existing pulse M

35 of the method. Gee)

An example of the functional scheme of the device, with the help of which the method of determining the length of the electric transmission line to the places of damage is carried out, is shown in the figure.

The device contains an adjustable frequency generator 1, a control and calculation device 2, which contains data exchange and indication means, a pulse generator C, a signal generator with a rectangular spectrum 4, 70 analog-to-digital converter 5, a switch 6, a matching and separation device 7, the test line 8 and - with a matched load 9. The output of the adjustable frequency generator 1 is connected to the pulse generator 2 and the signal generator with a rectangular spectrum 4. The outputs of the generators 2 and 4 are connected to the switch 6, the output of which is connected to the input of the matching device 7. The output of the matching device 7 is connected to the tested line 8, the other end of which 75 is loaded with the matching load 9.

The output of the matching device 7, the pulse generator Z and the signal generator with a rectangular spectrum 4 is connected to the analog-to-digital converter 5. The control and exchange device 2 is connected to the generator e of the controlled frequency 1, the pulse generator Z, the signal generator with rectangular spectrum 4, switch 6 and - analog-to-digital converter.

The method of determining the length of the electric transmission line to the places of damage to the electric line is carried out as follows.

Kz At the beginning of the measurement, the control device 2 switches the switch 6 to the output of the pulse generator 3.

The variable frequency generator 1 is set to the required pulse frequency of the pulse generator 3.

The control device with the help of an analog-to-digital converter determines the initial distances to Hinhomogeneities in the line, the amplitude and phase for each inhomogeneity.

After that, the control device switches the switch to the output of the square spectrum signal generator

P" 4, sets the required frequency of generating signals of variable frequency generator 1. The total phase and amplitude of the input signal are determined with the help of an analog-to-digital converter.

With the help of the formula presented above, using the results of pulse reflectometry and phase distance measurement, the control device calculates the specified distances to inhomogeneities in the communication line.

Sources of information 1. Patent of Ukraine Mo34710 A. Cl. 501К31/08 dated 03.15.2001 The method of determining the length of the electric transmission line to the place of damage / Yu.O. Skiruta, O.Yu. Kuznetsov // Bull. - 2001. -Mo2 65 2. A.S. 930224 /USSR/. A device for measuring the phase delay time of signals / V.G. Bazhenov, E.K.

Baturevych, S.M. Mayevsky - Publ. In B.I., 1982, Mo19

Z. Object research with the help of picosecond pulses / G.V. Hlebovich, A.V. Andriyanov, Yu.V.

Vvedensky and others; Ed. G.V. Hlebovich. - M.: Radio and communication, 1984. -256 p., illustrations. 4. Maevsky S.M., Bazhenov V.G., Baturevych E.K. Kuts Yu.V. Application of phaseometry methods for precision distance measurement. - Kyiv: Higher School. Publishing House at Kyiv. University of Technology, 1983. 84bs. 5. Kinkulkin I.E., Rubtsov V.D., Fabryk M.A. Phase method of determining coordinates. M.: Sovetskoe radio, 1979. - 280 p. 6. Maevsky S.M., Baturevych E.K., Bazhenov V.G., Grokholsky E.V. Precision measurement of electrical lengths! communication cable lines. Phase measurement methods in radio engineering. Tr. RI AN USSR, 1977, Mo27, p. 7/0.110-114. 7. Vernyk S.P., Kushnir F.V., Rudnytskyi V.B., Increasing the accuracy of measurements in communication technology. - M.: Radio and communication, 1981, p. 149-150.

Claims (1)

The formula of the invention is the method of determining the distances to the places of damage to the electric line, which includes dividing the test signal into reference and measurement, receiving the reflected signal, measuring the time of appearance of each reflection and measuring the phase differences between the received signal and the reference and calculating the lengths of the distances to inhomogeneities, which differs in that that the distances are calculated from the connections of the results of pulse reflectometry with the results of measuring the phase of signals at different frequencies, which are calculated according to the formulas: К А и . di U Tsvip(d) r Kk Ne dk ky A « U Ts,vip( du) i i - To k-i Ya yaz y gon chn Ga U vipaK a) ste « s nyu ek v bek - de dk - phase shift for K-I heterogeneity, determined by the pulse reflectometry method; h Ck- amplitude of the reflected signal from the K-th inhomogeneity; (Se) Asp,Fup 7 amplitude and phase, determined by the method of phasometry. - with . a (e)) t" - iz 50 more) because b5