RU2294289C1 - Mode of determination of lengthening of wires on plots between poles of high-voltage lines of electric transmissions - Google Patents

Abstract

FIELD: the invention refers to technical servicing of high-voltage lines of electric transmissions in the part of controlling accident-free conditions of the wires between the poles of high-voltage lines of electric transmissions.

SUBSTANCE: the technical result of the invention is the possibility to determine lengthening of the wires between the poles of high-voltage lines of electric transmissions without direct contact with the wires being under high-voltage and suspended to the poles of high-voltage lines of electric transmissions on a high altitude. The mode is characterized by periodic determinations of the lengths of the arcs of the wires between the poles of high-voltage lines of electric transmissions for finding out the lengthening of the wires under influence of own weight at each moment of time determinations according to which correlation dependence of lengthening of wires from the time of its determination is made.

EFFECT: allows forecasting the lengthening of wires for any period of time.

2 dwg

Description

The invention relates to the maintenance of high-voltage electric transmission lines (power transmission lines), namely, to monitor the trouble-free condition of wires being built and in operation of high-voltage power lines.

A known method for determining the location parameters of the contact wire of the railway track (patent RU 2191124 C2 7, 60 M 1/12, 2002.10.20). The essence of the method lies in the fact that two measurements are taken at points located on the same line perpendicular to the geometric axis of the path at the level of the rail heads, and determine from the geometric formulas the height of the position of the contact wire relative to the heads of the rails and the displacement of the contact wire relative to the geometric axis. In this case, the distance to the contact wire is measured relative to points (rail heads) located symmetrically with respect to the geometric axis of the path using an ultrasonic device.

The disadvantages of this method is that it determines only the relative position of the geometric axes of the contact wire and the railway track. In addition, the accuracy of linear measurements with an ultrasonic range finder is ± 100 mm, which is not enough to determine the elongation of the wire from sagging under its own weight. To fix the mentioned extension of the wires, linear measurements must be made with an accuracy of 3-5 mm.

A known method of measuring the tension of the spring cable (patent RU 2214334 7, 60 M 1/22, G 01 L 1/00, 2003.10.20), according to which determine the distance between the extreme points of suspension of the spring cable, the arrow of the sag and, knowing its linear weight , determine by the formula the magnitude of the tension of the spring cable used to suspend the contact wire on the railways.

The extension of the cable under the action of its own weight in the framework of this method cannot be obtained due to the uncertainty of the solution to this problem due to insufficient initial data and the corresponding actions.

The technical result of the invention is the ability to determine the elongation of the wires of high-voltage lines, excluding direct contact with them, and thereby providing control over the condition of the wires of high-voltage power lines.

The technical result is achieved by the fact that in the method for determining the elongation of wires in the sections between the supports of high voltage electric transmission lines (power transmission lines), according to the invention, in each section between the supports of the power transmission lines, after certain periods of time, the coordinates of the points of suspension of the wire to the supports and the coordinates of the point of maximum sag of wires under own weight, which determine the length of the arc of the wire between the points of its suspension on the supports according to the formula

- высотная отметка точки, лежащей на пересечении вертикальной линии, проходящей через точку максимального провисания проводов, и линии, соединяющей точки подвеса проводов на опорах ЛЭП на момент времени ее определения t_i;

- угол между горизонтальной линией и линией, соединяющей точки подвеса проводов на опорах ЛЭП на момент времени t_i, а величину удлинения получают как разность длины дуги провода одного и того же участка, полученной при втором и последующих периодических определениях, и первым ее определением по формулеwhere l (t _i ) is the length of the arc of the wire, determined at time t _i ; x _1i , y _1i , z _1i and x _2i , y _2i , z _2i are the spatial coordinates of the first and second points of suspension of wires to the power transmission towers, respectively, at the time of their determination t _i ; x _3i , y _3i , z _3i - spatial coordinates of the point of maximum sagging wires at the time of their determination t _i ;

- the elevation of the point lying at the intersection of the vertical line passing through the point of maximum sagging of the wires, and the line connecting the points of suspension of wires on the poles of power lines at the time of its determination t _i ;

- the angle between the horizontal line and the line connecting the points of suspension of the wires on the poles of the power lines at time t _i , and the elongation is obtained as the difference between the length of the arc of the wire of the same section, obtained during the second and subsequent periodic determinations, and its first determination by the formula

Δl _i = l (t _{i + 1} ) -l (t ₁ ),

where Δl _i is the elongation of the wires at time t _{i + 1} ; l (t ₁ ) is the initial length of the arc of wires at its first determination, at time t _i ; l (t _{i + 1} ) is the length of the arc of wires in the second and subsequent determinations of it at time t _{i + 1} , on each section of wires between the power transmission poles several lengthenings of wires Δl _i are obtained from periodic measurements corresponding to the time of their determination t _{i + 1} , according to these data, the correlation dependence of the extension on the time of its determination is derived, by which the extension of the wires for any period of time is determined and predicted.

The method is illustrated by drawings, where figure 1 shows a diagram for determining the length of the arc of the wire according to the coordinates of the points of suspension of the wire and the point of its maximum sag; figure 2 is a schematic diagram of the accumulated elongation of the wire according to the extrapolation schedule.

To obtain the length of the arc l, it is necessary to determine the spatial coordinates (x, y, z) of points 1, 2 - points of suspension of wires to the power transmission poles, and 3 - points of maximum sag of the wire in the span between the power transmission poles (Fig. 1).

Coordinates can be obtained by measuring the corresponding horizontal and vertical angles with an optomechanical theodolite and measuring the distance of the light range finder to points 1, 2 and 3, for which a prism reflector must be installed on these points. All these operations for angular and linear measurements can now be performed by most modern electronic total stations, but also with the installation of prism reflectors at points 1, 2 and 3. Considering that the installation of reflectors at points 1, 2 and 3, which are located on the wires, dangerous and impossible due to high voltage, the mentioned measuring systems for such conditions are not applicable.

It is possible to successfully solve this problem (determining the coordinates of points located on high-voltage wires of power lines without installing prism reflectors at determined points) using modern electronic total stations that have a mode of measuring distances without a reflector. As a result, it becomes possible to determine the coordinates of points in places where it is difficult to install a reflector (high altitude), dangerous and impossible. The range of measuring distances in the reflectorless mode for various devices of this class ranges from 350-600 m, the accuracy of measurements (determination of coordinates) is 3-5 mm.

As follows from the diagram in figure 1, the suspension points of the wires 1 and 2 can be at different levels, respectively, and the point of maximum sag 3 will be slightly offset relative to the middle of the span. Using an electronic total station in the reflectorless mode, the measurements determine the coordinates of points 1, 2 and 3: x ₁ , y ₁ , z ₁ ; x ₂ , y ₂ , z ₂ ; x ₃ , y ₃ , z ₃ . Having the coordinates, you can determine the length of the arc according to the following algorithm:

from here

where z ₄ - the elevation of point 4 (figure 1);

Where

after substituting (6) and (7) into (5), we obtain

now define h ':

h '= z ₄ -z ₃ ,

where from

The length of the arc can be determined by the well-known formula (Bronstein I.N., Semendyaev K.A. Handbook of Mathematics. State Publishing House of Physics and Mathematics, M., 1962):

Taking into account formulas (1) - (9), formula (10) can be transformed to the following form:

- высотная отметка точки 4, лежащей на пересечении вертикальной линии, проходящей через точку максимального провисания проводов 3, и линии, соединяющей точки подвеса проводов 1 и 2 на опорах ЛЭП;

- угол между горизонтальной линией и линией, соединяющей точки подвеса проводов 1 и 2 на опорах ЛЭП (фиг.1).where x ₁ , y ₁ , z ₁ and x ₂ , y ₂ , z ₂ are the spatial coordinates of the points 1 and 2 of the suspension of wires to the power transmission towers, respectively; x ₃ , y ₃ , z ₃ - spatial coordinates of the point of maximum sagging wires 3;

- the elevation of point 4, lying at the intersection of the vertical line passing through the point of maximum sag of wires 3, and the line connecting the suspension points of wires 1 and 2 on the poles of power lines;

- the angle between the horizontal line and the line connecting the suspension points of the wires 1 and 2 on the power transmission towers (Fig. 1).

The elongation of the wires in the sections between the power transmission line poles mainly occurs due to the sagging of the wires under their own weight under changing weather conditions (seasonal temperature changes, wind loads, glacier loads, etc.). Fundamentally, this elongation can be fixed as follows.

At time t ₁ we determine according to the above algorithm, the length of the arc of the wire between the supports 4 power lines - l (t ₁ ). After a certain period of time, for example, after 1 month, at time t _{2, we} again determine the length of the arc of the wire between the same power transmission line supports - l (t ₂ ). Then the absolute elongation from the sag under its own weight Δl ₁ can be determined as

Then this elongation can be expressed as a percentage of the initial arc length determined at time t ₁ :

Continuing monitoring of control over the extension of the wire, at time t ₃ we determine the length of the arc l (t ₃ ) and obtain a new absolute and relative elongation relative to the original length of the arc of the wire l (t ₁ ):

Having made the same definitions for time t ₄ , we obtain

Similar observations are made for time t ₅ , t ₆ , ..., t _i . When the relative elongation of the wire is reached, the critical elongation in this section must be eliminated emergency extension. This controls the extension of the wire of one span, the same control, according to the same scheme, is carried out by other wires of this span and by other spans, between other supports of the power transmission line, and where the relative elongation of the wires reaches a critical value, this section of the wires is transferred to the discharge emergency.

The above method allows you to record the process of lengthening the wires between the supports under the action of its own weight in time. And if you start to apply simultaneously from the moment the power line is put into operation, then we will fix the process of lengthening the wires from the very beginning.

For existing power lines, in which the process of lengthening the wires is already underway and is at some particular stage of development, it is possible, using the method described above, to evaluate the accumulated elongation from the moment the power line was started and take this into account when monitoring. It is proposed to do this by extrapolating the identified tendency of development of the process of elongation of wires in time.

By the method described above, Δl ₁ , Δl ₂ , ..., Δl _i are obtained (see formulas (1), (3), (5), while Δl ₁ corresponds to time t ₂ , Δl ₂ - to time t ₃ , Δl ₃ - time t ₄ , ..., Δl _i - time t _{i + 1.} According to these methods of mathematical statistics, we can obtain the correlation dependence Δl = f (t), which reflects the tendency of accumulation of elongation of wires in time . After substituting the time dependence of the power transmission line from the beginning of its operation until the beginning of periodic observations - T into this derived dependence, we obtain the accumulated elongation Ugi wire between transmission towers at the time of the first observation of opredelnie length of wire arc - Δl _T This analytic solution of this problem is to determine the accumulated extension can be solved graphically...

According to the same data, we plot the dependence of the elongation of the wire Δl on the time of its determination t (curve Δl = f (t) in figure 2). Knowing the time of existence of the power transmission line until the start of monitoring observations T, we postpone this value along the axis "t" of the graph from the point corresponding to time t ₁ (Fig.2). Given the trend of the graph Δl = f (t), we continue it until it intersects with the perpendicular restored from the t axis from the point with the abscissa (t ₁ + T) (i.e., n in FIG. 2). Then, from tn, we lower the perpendicular to the Δl axis, the intersection point with which will give the elongation Δl _T , which is the accumulated elongation of the wires during the time elapsed from the beginning of the operation of the power transmission line until the start of monitoring observations.

Obtained from the measurements Δl ₁ , Δl ₂ , ..., Δl _i , according to which the graph Δl = f (t) was constructed, are reduced to those extensions that would have occurred if the monitoring measurements started coinciding in time with the beginning of the transmission line operation:

where Δl _T is the accumulated elongation of wires during the time elapsed from the beginning of the operation of the power transmission lines to the moment of the beginning of monitoring observations, determined by the extrapolation schedule (figure 2). And further, according to the method determine:

where l '(t ₁ ) = l (t ₁ ) -Δl _T.

The obtained Δ _{i are} compared with the allowable elongation, whence a conclusion is made about the condition of the wires. At the same time, the monitoring started on this power line is continued, introducing Δl _T in each new definition of Δl _i as a correction (see formula (18). As a result, if we plot the corrections of the corrected elongations Δl 'on the time for determining the elongations t, we obtain a graph (curve Δl '= f (t) in figure 2), reflecting the elongation of the wire from the moment of its suspension to the power line supports. Formally speaking, the graph Δl' = f (t) is obtained by parallel shift of the graph Δl = f (t) by Δl _T along the Δl axis.

The graph Δl = f (t) (Fig. 2) is enough to build or determine the type of correlation depending on three or four points to identify the trend. Measurements to determine the length of the arc at various points in time in a first approximation are made 1 time per week. If the Δl _i values are small in absolute value and do not reveal a tendency for the elongation process, the frequency of monitoring observations should be reduced to 1 time in two weeks, up to 1 time per month, etc. Those. find a period between measurements, within which the elongation process will be recorded by the device in an explicit form, with a manifestation of a tendency to increase Δl _i in time.

Thus, using the derived correlation dependence Δl = f (t), it is possible to determine what extension of wires was at different points in time from the start of operation of this power line to the beginning of such periodic observations, and to predict the accumulation of extension of wires for any period of time forward by substituting in Δl = f (t) of the time of interest to us. For a more accurate forecast, both towards the past existence of the power transmission line and towards its future, it is necessary to continue periodic observations of the process of lengthening the wires and, taking into account the new data from these observations, make corrections to the equation of the correlation dependence Δl = f (t).

The advantage of the proposed method is the ability to determine the elongation of the wire (s) between the supports of high voltage power lines without direct contact with wires that are under high voltage and suspended from the power line supports at a sufficiently high height, that is, there is no need to disconnect the power lines during checking the technical condition of the wires.

The proposed method is intended to be used in the maintenance of high-voltage power lines in terms of monitoring the trouble-free condition of wires under construction and in operation of high-voltage power lines. It is also possible to use it to assess the condition of low-voltage power transmission wires, suspended contact wires for railway and tram-trolleybus vehicles.

Claims (1)

A method for determining the elongation of wires in the areas between the supports of high-voltage electric transmission lines (power transmission lines), characterized in that in each area between the power transmission lines supports, at certain time periods, the coordinates of the points of suspension of wires to the supports and the coordinates of the point of maximum sag of wires under their own weight are determined the length of the arc of the wire between the points of its suspension on the supports according to the formula

where l (t _i ) is the length of the arc of the wire, determined at time t _i ; x _1i , y _1i , z _1i and x _2i , y _2i , z _2i are the spatial coordinates of the first and second points of suspension of wires to the power transmission towers, respectively, at the time of their determination t _i ; x _3i , y _3i , z _3i - spatial coordinates of the point of maximum sagging wires at the time of their determination t _i ;

- the elevation of the point lying at the intersection of the vertical line passing through the point of maximum sagging of the wires, and the line connecting the points of suspension of wires on the poles of power lines at the time of its determination t _i ;

- the angle between the horizontal line and the line connecting the suspension points of the wires on the poles of power lines at time t _i , and the elongation is obtained as the difference between the length of the arc of the wire of the same section, obtained in the second and subsequent periodic determinations, and its first determination by the formula Δl _i = l (t _{i + 1} ) -l (t ₁ ), where Δl _i is the elongation of the wires at time t _{i + 1} ; l (t ₁ ) is the initial length of the arc of wires at its first determination at time t ₁ ; l (t _{i + 1} ) is the length of the arc of wires in the second and subsequent determinations at time t _{i + 1} , on each section of wires between the power transmission line supports, several wire extensions Δl _i are obtained from periodic measurements corresponding to their determination time t _{i + 1} , according to these data, the correlation dependence of the extension on the time of its determination is derived, which determines and predicts the extension of wires for any period of time.

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