RU2603247C1 - Method for locating damaged point of power transmission line - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: invention relates to electrical engineering and power engineering and can be used to locate a damaged point of a power transmission line. Electromagnetic waves occurring at point of damage and propagating to ends of line are detected. At moments of arrival of wave fronts to line ends difference of times of arrival of fronts of electromagnetic waves to line ends are measured and recorded. Point of damage is determined by summation of half-length of line, half of product of difference in time of arrival of fronts of electromagnetic waves at speed of propagation of electromagnetic waves, as well as a correction coefficient. Adjusting factor is defined as product of half-difference of arrival time of electromagnetic waves and electromagnetic wave propagation speed increment. Incremental velocity of propagation of electromagnetic waves is generated based on results of bypasses of power transmission line, which correspond to previous damages.

EFFECT: high accuracy of locating damaged point of power transmission line.

1 cl, 3 tbl, 3 dwg

Description

The invention relates to electrical engineering and electric power industry and can be used to determine the location of damage to the power line.

и $$t_2$$

превышения порогового значения суммой аварийных составляющих междуфазных напряжений и аварийных составляющих соответствующих междуфазных токов, умноженных на коэффициент, равный эквивалентному значению междуфазного волнового сопротивления, и по измеренной разности $$(t_1-t_2)$$

вычисляют расстояние до места повреждения.A known method of determining the distance to the place of damage to the power line [RF Patent No. 2472169 IPC G01R 31/08, publ. 01/10/2013, bull. No. 1], which consists in the fact that currents and phase voltages are measured at the first and second ends of the line, interphase currents and interphase voltages are formed from the measured currents and voltages, emergency components of interphase currents and emergency components of interphase voltages are isolated, fixed at the first and second ends line time points $$t_{\mathrm{one}}$$

and $$t_2$$

exceeding the threshold value by the sum of the emergency components of the interphase voltages and the emergency components of the corresponding interphase currents, multiplied by a coefficient equal to the equivalent value of the interphase wave impedance, and the measured difference $$(t_{\mathrm{one}}-t_2)$$

calculate the distance to the place of damage.

The disadvantage of this method of determining the distance to the place of damage to the power line is low accuracy.

прихода фронтов электромагнитных волн к концам линии, а место повреждения определяют путем суммирования половинной длины линии и половинного произведения разности времени $$\Delta t$$

на скорость распространения электромагнитных волн вдоль линии.Also known is a method of determining the location of damage to a power line [Shalyt G.M. Determination of places of damage in electrical networks. - M .: Energoatomizdat, 1982, p. 18-19], using the wave method of two-sided measurements, which fixes electromagnetic waves that occur at the time of damage and propagate to the ends of the line, at the moments when the wave fronts reach the ends of the line, measure and fix the time difference $$\Delta t$$

the arrival of the fronts of electromagnetic waves to the ends of the line, and the place of damage is determined by summing the half length of the line and the half product of the time difference $$\Delta t$$

on the speed of propagation of electromagnetic waves along the line.

In order to ensure accuracy in determining the distance to the damage site, modern technical solutions, which are a variation of the wave method of two-sided measurements, use a global positioning system [for example, US Patent No. 6597180 B1, publ. 07/22/2003].

The disadvantage of this method of determining the location of damage to the power line is low accuracy.

The closest technical solution to the alleged invention is a method for determining the location of damage to the power line [RF Patent No. 2555195 IPC G01R 31/08, publ. 07/10/2015, bull. No. 19], according to which electromagnetic waves that occur at the site of damage and propagate to the ends of the line are recorded, at the moments when the wave fronts reach the ends of the line, they measure and record the difference in the arrival time of the fronts of electromagnetic waves to the ends of the line. According to the method, before determining the location of damage, a simulation of damage is carried out taking into account the design features of the power transmission line and subsequent fixation of the time of arrival of the fronts of electromagnetic waves to the ends of the line, the correction results are determined by modeling, and the location of the damage is determined by summing the half length of the line, half the product of the difference of the time of arrival of the fronts electromagnetic waves on the speed of propagation of electromagnetic waves, as well as corrective ffitsienta.

Along with the accuracy of fixing the time of arrival of the electromagnetic wave to the ends of the line, an important factor affecting the calculation of the distance to damage is the speed of propagation of the electromagnetic wave. In the prototype method, it is assumed to compensate for errors in determining the location of damage to the power line using simulation and obtaining a correction factor that takes into account the change in the propagation speed of the electromagnetic wave along the line.

Model experiments involve the use of adequate simulation models, which are quite difficult to implement in relation to the features of each analyzed power transmission line.

From the point of view of operating electric grid enterprises with statistics of damage to a particular power line, it is advisable to use data on emergency outages for a preliminary estimate of the propagation speed of electromagnetic waves.

The objective of the invention is to improve the accuracy of the method for determining the location of damage to the power line.

The problem is achieved by the method of determining the place of damage of the power line, which fixes the electromagnetic waves that occur at the place of damage and propagating to the ends of the line, at the moments when the wave fronts reach the ends of the line, measure and record the difference in the time of arrival of the fronts of electromagnetic waves to the ends of the line, determine the place of damage by summing half the length of the line, half the product of the difference in the time of arrival of the fronts of electromagnetic waves by the speed of propagation of ele electromagnetic waves, as well as a correction factor. Moreover, according to the method, the correction coefficient is determined as the product of half the difference in the time of arrival of electromagnetic waves by the increment of the propagation speed of electromagnetic waves, and the increment of the propagation velocity of electromagnetic waves is formed according to the results of bypasses of the power line corresponding to previously damaged ones.

The proposed method is implemented as follows.

Circuit solutions for determining the location of damage to the power line can be performed using equipment from various manufacturers, for example:

- Canadian company Qualitrol, the technical solutions of which are presented on the website of the Russian official representative www.navi-spb.ru;

- microprocessor-based device for determining the location of damage “Bresler-0107.090” LLC “NPP Bresler”, 428018 Cheboksary, st. Afanasyeva, d.13;

- a number of other manufacturers.

However, the speed of light c is adopted as the speed of propagation of electromagnetic waves through power lines in these devices, which leads to errors in calculating the distance for real damage. Therefore, before starting to determine the location of damage to the power line according to the proposed method, the speed of propagation of electromagnetic waves is refined.

The principles for clarifying the propagation speed are illustrated by an example.

Suppose there is an A-B power line connecting substations A and B (Fig. 1), on which N damage has occurred (i = 1, ..., N). For each of the damages, there are the results of line detours with the calculation of the distance x ₁ , ..., x _i, ..., x _N and the errors in the wave determination of the damage location of the analyzed power transmission line Δx ₁ , ..., Δx _i , ..., Δx _N due to the difference between the calculated and real values.

Given the data of previous damage to the power lines, we write

$$\begin{array}{l}\Delta x_{\mathrm{one}}+x_{\mathrm{one}}=0.5[L+v\cdot (t_{A\mathrm{one}}-t_{B\mathrm{one}})];\\ \Delta x_2+x_2=0.5[L+v\cdot (t_{A2}-t_{B2})];\\ \mathrm{...}\\ \Delta x_i+x_i=0.5[L+v\cdot (t_{Ai}-t_{Bi})];\\ \mathrm{...}\\ \Delta x_N+x_N=0.5[L+v\cdot (t_{AN}-t_{BN})],\end{array}$$

       (one)

where t _Аi and t _Вi, respectively, the time of arrival of the front of the electromagnetic wave at substation A and B at the i-th damage; L is the length of the power line; v is the propagation velocity of the electromagnetic wave.

Move the term 0.5 · L to the left side of the expression and introduce the matrix notation

$$X=\left[\begin{array}{l}\Delta x_{\mathrm{one}}+x_{\mathrm{one}}-0.5L\\ \Delta x_2+x_2-0.5L\\ \mathrm{...}\\ \Delta x_i+x_i-0.5L\\ \mathrm{...}\\ \Delta x_N+x_N-0.5L\end{array}\right],T=0.5\cdot \left[\begin{array}{l}{t}_{A\mathrm{one}}-t_{B\mathrm{one}}\\ t_{A2}-t_{B2}\\ \mathrm{...}\\ t_{Ai}-t_{Bi}\\ \mathrm{...}\\ t_{AN}-t_{BN}\end{array}\right]$$

       (2)

Then the expression can be converted to

$$X=T\cdot v,$$

       (3)

Using the least squares method, we obtain the adjusted velocity value

$$v={(T^T\cdot T)}^{-\mathrm{one}}\cdot T^T\cdot X.$$

       (four)

After receiving the specified speed value, a speed increment Δv is formed, which is involved in the calculation of the correction coefficient

                                    Δv = s - v, (5)

where c is the speed of light.

It is important to note that for a more accurate wave determination of the location of a power line damage, it is necessary to select data from previous power line damage as close as possible to the estimated damage site.

After installing the sets of the device wave definition of damage to the opposite ends of the power lines, the proposed method can be implemented. In the event of damage, for example, breakdown of the insulation of an overhead power line to the ground, electromagnetic voltage waves propagating in both directions are formed. The indicated waves are registered by the sets of the device for wave determination of damage sites. Registration is based on a synchronized countdown at both ends of the line using a global positioning system. Information about the time of registration of an electromagnetic wave from the opposite end of a power transmission line is transmitted using a communication channel to a kit that calculates the distance to damage.

From this point of view, to ensure high accuracy of the proposed method, it is advisable to apply the following sequence of operations in the event of damage to the power lines.

1. At the moments when the fronts reach waves from damage to the ends of the line, measuring and fixing the difference in the time of arrival of the fronts of electromagnetic waves to the ends of the line.

2. The calculation of the distance to the place of damage x under the assumption that the propagation velocity of electromagnetic waves is equal to the speed of light [G. Shalyt Determination of places of damage in electrical networks. - M .: Energoatomizdat, 1982, p. 18-19]

[L+ с

Δt],x = 0.5

[L + s

Δt],

where for the considered example (figure 1) Δt = (t _A - t _B ).

3. The selection from the array of previous damage set of points (for example, three), closest to the proposed location of the damage (figure 1).

4. Based on the totality of the selected points, the calculation of the specified speed value according to the expression (4).

5. Calculation of correction factor Δx _armature

Δv = s - v,

Δt.Δx _core. = Δv

Δt.

6. Calculation of the specified distance to the place of damage x _dot. taking into account the correction factor

x _dot = X - Δx _core. .

The accuracy of the proposed method is analyzed using the PSCAD software product. A section of a 220 kV network was modeled (Fig. 2). The power transmission line parameters of a 220 kV network section are given in Table 1.

Table 1 - Parameters of sections of a simulated 220 kV electric network

Plot Length, km Wire mark Cable mark Type of support Soil resistivity, Ohm · m i-j 57 AC-400/51 S-70 P-220-2t 4000 j-m 46 ASO-300/39 S-70 PB-220-1 one hundred m-n 132 AC-240/32 S-70 P-220-1t 1000

The sets of the wave device for determining the location of damage are located at nodes i and m, data on errors in calculating the distance for previous damage are given in table. 2.

Table 2 - the error in calculating the distance with previous damage to the power lines

Actual distance to damage from node i, km Error in calculating the distance to damage, m 10 530 thirty 445 fifty 345 60 310 80 210 one hundred 95 110 45 150 -170 190 -415 230 -705

Short circuits were simulated at points that did not coincide with those previously recorded in the procedures for determining the location of damage. The adjusted speed was calculated by the three points closest to the short circuit. The results of simulation tests are summarized in table. 3.

Table 3 - Comparison of the accuracy of two-sided wave determination of the location of damage [G. Shalyt Determination of places of damage in electrical networks. - M .: Energoatomizdat, 1982, p. 18-19] and the proposed method with the specification of speed

The distance from the node i to the simulated damage site, km Time of arrival of an electromagnetic wave to PSi t _i , ms The time of arrival of an electromagnetic wave to PSm t _m , ms Calculation of the distance by the two-sided wave method, m Error of calculation of the distance by the two-sided wave method, m Refined speed of propagation of electromagnetic waves, m / s Calculation of the distance to damage by the proposed method, m Error in calculating the distance by the proposed method, m one 1,0035 1.7825 650 350 299068021 1013 -13 twenty 1,0669 1,719 19685 315 299005707 20009 -9 40 1,1337 1.6522 39725 275 298910990 40007 -7 70 1,2338 1.5518 69800 200 298809984 69989 eleven 90 1,3007 1,485 89855 145 298535402 89990 10 130 1.4345 1.3512 129995 5 298926842 129950 fifty 170 1,5684 1,2174 170150 -150 299102256 169992 8 210 1.7025 1,0837 210320 -320 298883348 209975 25 234 1.7833 1,0035 234470 -470 298861000 234026 -26

Note: the error in estimating distances in the simulation was 60 m.

The analysis of Table 3 shows that the error of the proposed method for determining the location of damage to the power line lies within the error of the simulation, due to discrete time readings.

A comparison of the errors of methods for determining the location of damage to the power line is presented in figure 3. In figure 3, the solid line corresponds to the method [Shalyt G.M. Determination of places of damage in electrical networks. - M .: Energoatomizdat, 1982, p. 18-19], and dashed line - to the proposed method taking into account correcting coefficients based on the refinement of the propagation speed of electromagnetic waves.

Studies have shown (figure 3, table 3) that the error in determining the location of damage to the power line by the proposed method does not depend on the distance to the place of damage.

Thus, by preliminary clarifying the speed of propagation of electromagnetic waves through power lines using data from operational emergency statistics, obtaining corrective coefficients on this basis, the aim of the invention is to increase the accuracy of determining the location of damage to a power line.

Claims (1)

The method for determining the place of damage of the power line, which fixes electromagnetic waves that occur at the place of damage and propagating to the ends of the line, at the moments when the wave fronts reach the ends of the line, measure and record the difference in the time of arrival of the fronts of electromagnetic waves to the ends of the line, determine the place of damage by summing half the length the line, the half product of the difference in the arrival time of the fronts of electromagnetic waves by the propagation velocity of electromagnetic waves, and also correctly factor, characterized in that the correction factor is defined as the product of half the difference in the time of arrival of electromagnetic waves by the increment of the propagation velocity of electromagnetic waves, and the increment of the propagation velocity of electromagnetic waves is formed according to the results of bypasses of the power line corresponding to previous damage.

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