CN115248359A - A traveling wave ranging method and system considering line length variation - Google Patents

Abstract

The invention discloses a traveling wave ranging method and system which takes into account the change of line length. The method includes: calculating conductor allowance based on conductor parameters, spans, year-round weather and environmental conditions and installation parameters of towers in a target transmission line. Use stress and specific load; calculate the critical span of the conductor based on the allowable stress of the conductor and the specific load; calculate the actual line length of the target span under any current conditions based on the critical span and the line state equation, repeat Calculate the actual line length of each gear distance and accumulate the actual line length; based on the actual line total length, calculate the correction coefficient under the corresponding conditions; modify the double-ended ranging formula according to the determined correction coefficient, and calculate the fault location correction value to determine and correct the fault point.

Description

A traveling wave ranging method and system considering the change of line length

technical field

The present invention relates to the technical field of transmission line fault location, and more specifically, to a traveling wave ranging method and system taking into account the change of line length.

Background technique

Accurate fault location of transmission lines in power systems can reduce the burden of line inspection and shorten the time for fault elimination, which is of great significance for improving power supply reliability of power systems and reducing power outage losses.

At present, the fault location methods used in engineering mainly include impedance method and traveling wave method. When the transition resistance is large, it will affect the ranging accuracy of the impedance method. The traveling wave method only needs to calculate the time when the fault traveling wave arrives at the busbar, and calculates the fault point in combination with the traveling wave velocity, which is not affected by the fault type and transition resistance, and theoretically has higher ranging accuracy. The time difference between the waves arriving at the endpoints on both sides and the time difference between the initial traveling wave and the reflected wave at the fault point arriving at the same measurement end can be divided into single-ended method and double-ended method.

At present, the double-terminal method is widely used. It only needs to monitor the accurate time when the initial traveling wave of the fault point arrives at the two measurement terminals to complete the positioning, and the reliability of distance measurement is high. However, the accuracy of traveling wave ranging is affected by the parameters of the tested line. An important parameter required by the basic principle of double-ended traveling wave ranging is the total length of the line, but the total length of the line is not a constant value and will cause ranging errors, resulting in line The main factor of the length error is the sag, and the range of the sag varies greatly with the tension of the tower and the terrain. At the same time, the line wire has the characteristics of thermal expansion and cold contraction, so the length of the line will also change with the change of seasonal temperature. A large line length change will lead to traveling wave ranging errors of up to several kilometers. If the fault occurs in a more complex terrain, this change will cause great difficulties in maintenance work. The actual distribution parameters of the line change with the surrounding environment, so the length of the line becomes a time variable, which makes the fault traveling wave location error larger.

Therefore, a technique is needed to realize traveling wave ranging taking into account the variation of the line length.

SUMMARY OF THE INVENTION

The technical solution of the present invention provides a traveling wave ranging method and system taking into account the change of the line length, so as to solve the problem of how to perform traveling wave ranging in consideration of the line length change.

In order to solve the above problems, the present invention provides a traveling wave ranging method that takes into account changes in line length, the method comprising:

Calculate the allowable stress and specific load of the conductor based on the conductor parameters, span, annual weather and environmental conditions and tower installation parameters of the target transmission line;

Calculate the critical span of the wire based on the allowable stress of the wire and the specific load;

Calculate the actual line length of the target span under any current condition based on the critical span and the line state equation, repeatedly calculate the actual line length of each span and accumulate to obtain the actual line length;

Based on the full length of the actual line, calculate a correction coefficient under corresponding conditions;

Correct the double-terminal ranging formula according to the determined correction coefficient, calculate the corrected value of the fault location, and determine the corrected fault point.

Preferably, the wire parameters include: rated breaking force T _N , elastic modulus E, linear expansion coefficient α, cross-sectional area A, overhead line unit length q, strand diameter d, overhead line design safety factor k, overhead line body shape coefficient μ _sc ;

The span includes multiple spans ranging from 100 to 1000m;

The annual weather and environmental conditions include: average temperature, maximum temperature, minimum temperature, maximum ice thickness and temperature, maximum wind speed, wind speed unevenness coefficient α _f , overhead line wind load adjustment coefficient β _c in each season;

The tower installation parameters include: height difference and height difference angle.

Preferably, the calculation of the allowable stress of the wire includes:

Among them, σ _p is the tensile strength of the overhead line, k is the design safety factor of the overhead line is 2.5, the comprehensive breaking force T _P is 95% of the rated breaking force T _N , A is the cross-sectional area of the wire, and T _N is the rated tensile strength of the wire Breaking force, [σ] is the allowable stress of the wire.

Preferably, the specific load includes: self-weight specific load γ ₁ , ice specific load γ ₂ , vertical total specific load γ ₃ , ice-free wind pressure specific load γ ₄ , ice-covered wind pressure specific load γ ₅ , ice-free specific load Comprehensive specific load γ ₆ , icing comprehensive specific load γ ₇ .

Preferably, the actual line length of the target gear distance under any current condition is calculated based on the critical gear distance and the line state equation:

Among them, L is the actual length of the wire, l is the length of the span, _σ0 is the horizontal stress of the wire, β is the elevation angle difference, cosβ is the cosine value of the elevation difference angle, and γ is the specific load;

Repeat the above calculation process to calculate the actual line length l _x of each span of the target line, and accumulate the actual line length L according to the actual line length l _x of each span.

Based on the full length of the actual line, calculate the correction coefficient under the corresponding conditions:

Among them, l is the total length of the gear distance, and K is the correction coefficient in this state.

Preferably, said correcting the double-ended ranging formula according to the determined correction coefficient, calculating the corrected value of the fault location, and determining the corrected fault point include:

Among them, K is the correction coefficient in this state, l is the total length of the span line, L _M is the distance from the fault point to the end point of M, v is the traveling wave velocity, and _t1 is the initial traveling wave from the fault point to the first end of the wire The elapsed time of M, _t2 is the elapsed time for the initial traveling wave to reach the second end N of the conductor from the fault point.

Based on another aspect of the present invention, the present invention provides a traveling wave ranging system that takes into account changes in line length, and the system includes:

A calculation unit, used to calculate the allowable stress and specific load of the conductor based on the conductor parameters, span, annual weather and environmental conditions and tower installation parameters of the conductor in the target transmission line; The critical span of the wire; calculate the actual line length of the target span under any current condition based on the critical span and the line state equation, repeatedly calculate the actual line length of each span and accumulate the actual line length; based on the The correction coefficient under the corresponding conditions for calculating the total length of the actual line is described;

The result unit is used to correct the double-terminal ranging formula according to the determined correction coefficient, calculate the corrected value of the fault position, and determine the corrected fault point.

Preferably, the wire parameters include: rated breaking force T _N , elastic modulus E, linear expansion coefficient α, cross-sectional area A, overhead line unit length q, strand diameter d, overhead line design safety factor k, overhead line body shape coefficient μ _sc ;

The span includes multiple spans ranging from 100 to 1000m;

The annual weather and environmental conditions include: average temperature, maximum temperature, minimum temperature, maximum ice thickness and temperature, maximum wind speed, wind speed unevenness coefficient α _f , overhead line wind load adjustment coefficient β _c in each season;

The tower installation parameters include: height difference and height difference angle.

Preferably, the calculation of the allowable stress of the wire includes:

Among them, σ _p is the tensile strength of the overhead line, k is the design safety factor of the overhead line is 2.5, the comprehensive breaking force T _P is 95% of the rated breaking force T _N , A is the cross-sectional area of the wire, and T _N is the rated tensile strength of the wire Breaking force, [σ] is the allowable stress of the wire.

Preferably, the specific load includes: self-weight specific load γ ₁ , ice specific load γ ₂ , vertical total specific load γ ₃ , ice-free wind pressure specific load γ ₄ , ice-covered wind pressure specific load γ ₅ , ice-free specific load Comprehensive specific load γ ₆ , icing comprehensive specific load γ ₇ .

Preferably, the actual line length of the target gear distance under any current condition is calculated based on the critical gear distance and the line state equation:

Among them, L is the actual length of the conductor, l _x is the length of the span, σ ₀ is the horizontal stress of the conductor, β is the elevation angle difference, cosβ is the cosine value of the elevation difference angle, and γ is the specific load;

Repeat the above calculation process to calculate the actual line length l _x of each span of the target line, and accumulate the actual line length L according to the actual line length l _x of each span.

Based on the full length of the actual line, calculate the correction coefficient under the corresponding conditions:

Among them, l is the total length of the gear distance, and K is the correction coefficient in this state.

Preferably, the result unit is used to correct the double-ended ranging formula according to the determined correction coefficient, calculate the corrected value of the fault location, and determine the corrected fault point, including:

Among them, K is the correction coefficient in this state, l is the total length of the span line, L _M is the distance from the fault point to the end point of M, v is the traveling wave velocity, and _t1 is the initial traveling wave from the fault point to the first end of the wire The elapsed time of M, _t2 is the elapsed time for the initial traveling wave to reach the second end N of the conductor from the fault point.

The technical solution of the present invention proposes a traveling wave ranging method that takes into account the change of the line length, considers various factors affecting the change of the line length such as sag, temperature, icing, and wind force, and proposes a calculation method for calculating the actual line length in a targeted manner. It eliminates the fault location error caused by the change of line length with weather and environmental factors, and effectively improves the accuracy of traveling wave distance measurement.

Description of drawings

A more complete understanding of the exemplary embodiments of the present invention can be had by referring to the following drawings:

Fig. 1 is a flow chart of a traveling wave ranging method that takes into account changes in line length according to a preferred embodiment of the present invention;

Fig. 2 is a schematic diagram of dual-terminal ranging according to a preferred embodiment of the present invention; and

Fig. 3 is a structural diagram of a traveling wave ranging system considering the change of line length according to a preferred embodiment of the present invention.

Detailed ways

Exemplary embodiments of the present invention will now be described with reference to the drawings; however, the present invention may be embodied in many different forms and are not limited to the embodiments described herein, which are provided for the purpose of exhaustively and completely disclosing the present invention. invention and fully convey the scope of the invention to those skilled in the art. The terms used in the exemplary embodiments shown in the drawings do not limit the present invention. In the figures, the same units/elements are given the same reference numerals.

Unless otherwise specified, the terms (including scientific and technical terms) used herein have the commonly understood meanings to those skilled in the art. In addition, it can be understood that terms defined by commonly used dictionaries should be understood to have consistent meanings in the context of their related fields, and should not be understood as idealized or overly formal meanings.

Fig. 1 is a flow chart of a traveling wave ranging method that takes into account changes in line length according to a preferred embodiment of the present invention. The invention proposes a traveling wave ranging method considering the change of the line length, so as to solve the problems in the current traveling wave ranging such as low positioning accuracy and great influence of line sag.

As shown in Figure 1, the present invention provides a traveling wave ranging method that takes into account changes in line length, the method includes:

Step 101: Calculate the allowable stress and specific load of the conductor based on the conductor parameters, span, annual weather and environmental conditions and tower installation parameters of the target transmission line;

Preferably, the wire parameters include: rated breaking force T _N , elastic modulus E, linear expansion coefficient α, cross-sectional area A, overhead line unit length q, strand diameter d, overhead line design safety factor k, and overhead line shape Coefficient μ _sc ;

The span includes various spans from 100 to 1000m;

Annual weather and environmental conditions include: average temperature, maximum temperature, minimum temperature, maximum ice thickness and temperature, maximum wind speed, wind speed unevenness coefficient α _f , overhead line wind load adjustment coefficient β _c in each season;

Tower installation parameters include: height difference, height difference angle.

Preferably, the allowable stress of the wire is calculated, including:

Among them, σ _p is the tensile strength of the overhead line, k is the design safety factor of the overhead line is 2.5, the comprehensive breaking force T _P is 95% of the rated breaking force T _N , A is the cross-sectional area of the wire, and T _N is the rated tensile strength of the wire Breaking force, [σ] is the allowable stress of the wire.

Preferably, the specific load includes: self-weight specific load γ ₁ , ice specific load γ ₂ , vertical total specific load γ ₃ , ice-free wind pressure specific load γ ₄ , ice-covered wind pressure specific load γ ₅ , and ice-free comprehensive ratio Carrying γ ₆ , icing comprehensive specific carrying γ ₇ .

The present invention is based on the conductor parameters of the target project, the gear distance, the annual weather and environmental conditions, and the installation conditions of poles and towers. Calculate the allowable stress [σ] and seven specific loads γ of the wire.

The conductor parameters of the first span of the target project mainly include rated breaking force T _N , elastic modulus E, linear expansion coefficient α, cross-sectional area A, unit length q of overhead lines, diameter d of strands, design safety factor k of overhead lines, overhead line The shape coefficient μ _sc of the line.

The project of the present invention can include multiple spans such as 100 to 1000m, calculate the ratio of various spans of the same wire model, and calculate the line length of each part according to the ratio of the span.

Under a single span, the annual weather and environmental conditions mainly include the average temperature, maximum temperature, minimum temperature, maximum ice thickness and temperature, maximum wind speed, wind speed unevenness coefficient α _f , overhead line wind load adjustment coefficient β in each season _c .

The relevant parameters of the tower mainly include: height difference, height difference angle, and the influence of tower shape is not considered.

Calculation of the allowable stress of the conductor requires: rated breaking force T _N , design safety factor k of the overhead line, and cross-sectional area A. According to the calculation formulas (1) and (2) for the allowable stress [σ] of the overhead line, the allowable stress of the overhead line can be obtained.

Among them, is the tensile strength of the overhead line, k is the design safety factor of the overhead line is 2.5, and the comprehensive breaking force T _P is 95% of the rated breaking force T _N .

The specific loads of the above-mentioned 7 lines in the present invention are respectively self-weight specific load γ ₁ , ice specific load γ ₂ , vertical total specific load γ ₃ , ice-free wind pressure specific load γ ₄ , ice-covered wind pressure specific load γ ₅ , and ice-free specific load Comprehensive specific load γ ₆ , icing comprehensive specific load γ ₇ . The parameters needed to calculate the seven specific loads are: the unit length q of the overhead wire, the cross-sectional area A of the overhead wire, the acceleration of gravity g, the thickness of ice coating b, the outer diameter of the overhead wire d, the wind speed unevenness coefficient α _f , the overhead Line wind load adjustment coefficient β _c , shape coefficient μ _sc of overhead lines, angle θ between wind direction and line direction, wind pressure W ^v , icing wind load increase coefficient B. The corresponding specific load can be obtained by bringing the above parameters into the specific load formula of the line.

Step 102: Calculate the critical span of the conductor based on the allowable stress and specific load of the conductor;

The present invention calculates the critical span, and the calculation of the critical span requires four kinds of weather conditions as control conditions, and the critical span is calculated according to the known parameters of maximum temperature, maximum wind speed, ice-covered wind, annual average temperature, and obtained specific load value. There is a critical span between every two of the four control conditions, and six critical spans can be obtained by using the state equation of the line.

The present invention obtains the γ _i /[σ ₀ ] _i value of the control condition, and arranges an effective critical span discrimination table based on this value, and can select several effective critical spans from 6 critical spans through the table.

Step 103: Calculate the actual line length of the target span under any current condition based on the critical span and the state equation of the line, repeatedly calculate the actual line length of each span and accumulate the actual line length;

Step 104: Based on the actual full length of the line, calculate the correction coefficient under the corresponding conditions; preferably, calculate the actual line length of the target span under any current condition based on the critical span and the line state equation:

Among them, L is the actual length of the conductor, l _x is the length of the span, σ ₀ is the horizontal stress of the conductor, β is the elevation angle difference, cosβ is the cosine value of the elevation difference angle, and γ is the specific load;

Repeat the above calculation process to calculate the actual line length l _x of each span of the target line, and accumulate the actual line length L according to the actual line length l _x of each span.

Based on the actual total length of the line, calculate the correction factor under the corresponding conditions:

Among them, l is the total length of the gear distance, and K is the correction coefficient in this state.

The present invention calculates the actual line length and the correction coefficient, and can calculate the horizontal stress σ ₀ of the one-gauge conductor in the current arbitrary state according to the critical span and line state equation calculated above, and finally through the line length calculation formula (3) Obtain the actual line length of the first gear distance of the target.

The present invention calculates repeatedly, and can list the relatively accurate actual line length under different spans under different weather conditions throughout the year in this project. The total length L of the actual line can be known by accumulating the distances, different types of conductors, and line lengths under the same environmental conditions, and the error accuracy can meet the error requirements of traveling wave ranging. Repeat the above calculation process to calculate the actual line length l _x of each span of the target line, and accumulate the actual line length L according to the actual line length l _x of each span.

According to the comparison between the actual length of the line and the length of the span line in the table, the correction coefficient table can be obtained, and the formula is as follows:

in,

L is the total length of the actual line,

l is the total length of the span line,

K is the correction coefficient in this state.

Step 105: Correct the double-terminal ranging formula according to the determined correction coefficient, calculate the corrected value of the fault location, and determine the corrected fault point.

Preferably, the double-ended ranging formula is corrected according to the determined correction coefficient, the fault position correction value is calculated, and the corrected fault point is determined, including:

Among them, K is the correction coefficient in this state, l is the total length of the span line, L _M is the distance from the fault point to the end point of M, v is the traveling wave velocity, and _t1 is the initial traveling wave from the fault point to the first end of the wire The elapsed time of M, _t2 is the elapsed time for the initial traveling wave to reach the second end N of the conductor from the fault point.

The invention corrects the double-end ranging formula according to the full length parameter of the line.

Bring the above correction coefficient into the traditional double-terminal ranging formula for improvement. The revised double-terminal ranging formula is as follows:

in,

L _M is the distance from the fault point to the end point of M, v is the wave velocity,

t ₁ is the time elapsed by the initial traveling wave from the fault point to the end point of M,

t ₂ is the elapsed time for the initial traveling wave to reach the N terminal from the fault point.

The modified double-terminal ranging formula of the present invention can realize the fault location function based on the optimization of the uniformly changing line length under a certain state (span, weather conditions, towers). This patent is applied to the method of calculating the actual line length by superimposing environmental conditions such as temperature, icing, and height difference on the basis of the wire temperature to calculate the actual line length. Therefore, changes such as heavy load, light load, and load are not considered.

The present invention proposes a traveling wave ranging method that takes into account changes in line length, considers various factors affecting line length changes such as sag, temperature, icing, and wind force, and proposes a calculation method for calculating the actual line length in a targeted manner, eliminating the need for The fault location error caused by the change of line length with weather and environmental factors effectively improves the accuracy of traveling wave ranging.

Table 1 Parameter table of four control conditions

Table 2 Critical Gap Discrimination Table

A traveling wave ranging method that takes into account the change of line length provided by the present invention is described in detail, and the correctness of the present invention is proved by field data.

According to a project design manual, the local meteorological bureau, and relevant line length calculation documents, the target project conductor parameters, span ratio, annual weather and environmental conditions, and tower installation conditions were collected.

According to the known parameter conditions and formulas (1), (2) and the specific load general calculation formula, calculate the allowable stress [σ] of the conductor and seven kinds of specific load γ, according to the known parameters of the maximum temperature, maximum wind speed, wind , annual average temperature and four control conditions, that is, Table 1. According to the 4 control conditions and the line state equation, calculate 6 kinds of critical spans and establish the critical span discrimination table Table 2. According to the formula γ _i /[σ ₀ ] _i, it is effective For the critical span, calculate the actual line length and correction coefficient according to formulas (3) and (4). According to the full length parameter of the line, the formula of double-end distance measurement is revised, that is, the formula (5).

This application provides a calculation method for calculating the actual line length in consideration of various factors affecting the line length such as sag, temperature, icing, and wind force, which eliminates the fault location error caused by the change of line length with weather and environmental factors, and is effective In order to improve the accuracy of traveling wave ranging.

Fig. 3 is a structural diagram of a traveling wave ranging system considering the change of line length according to a preferred embodiment of the present invention. As shown in Figure 3, the present invention provides a traveling wave ranging system that takes into account changes in line length, and the system includes:

The calculation unit 301 is used to calculate the allowable stress and specific load of the conductor based on the conductor parameters, span, annual weather and environmental conditions and tower installation parameters of the conductor in the target transmission line; calculate the critical load of the conductor based on the allowable stress and specific load of the conductor Gap: Calculate the actual line length of the target span under any current condition based on the critical span and the line state equation, repeatedly calculate the actual line length of each span and accumulate to obtain the actual line length; based on the actual line length, calculate Correction coefficient under corresponding conditions;

Preferably, the wire parameters include: rated breaking force T _N , elastic modulus E, linear expansion coefficient α, cross-sectional area A, overhead line unit length q, strand diameter d, overhead line design safety factor k, and overhead line shape Coefficient μ _sc ;

The span includes various spans from 100 to 1000m;

Annual weather and environmental conditions include: average temperature, maximum temperature, minimum temperature, maximum ice thickness and temperature, maximum wind speed, wind speed unevenness coefficient α _f , overhead line wind load adjustment coefficient β _c in each season;

Tower installation parameters include: height difference, height difference angle.

Preferably, the allowable stress of the wire is calculated, including:

Among them, σ _p is the tensile strength of the overhead line, k is the design safety factor of the overhead line is 2.5, the comprehensive breaking force T _P is 95% of the rated breaking force T _N , A is the cross-sectional area of the wire, and T _N is the rated tensile strength of the wire Breaking force, [σ] is the allowable stress of the wire.

Preferably, the specific load includes: self-weight specific load γ ₁ , ice specific load γ ₂ , vertical total specific load γ ₃ , ice-free wind pressure specific load γ ₄ , ice-covered wind pressure specific load γ ₅ , and ice-free comprehensive ratio Carrying γ ₆ , icing comprehensive specific carrying γ ₇ .

Preferably, the actual line length of the target span under any current condition is calculated based on the critical span and the line state equation:

Among them, L is the actual length of the conductor, l _x is the length of the span, σ ₀ is the horizontal stress of the conductor, β is the elevation angle difference, cosβ is the cosine value of the elevation difference angle, and γ is the specific load;

Repeat the above calculation process to calculate the actual line length l _x of each span of the target line, and accumulate the actual line length L according to the actual line length l _x of each span.

Based on the actual total length of the line, calculate the correction factor under the corresponding conditions:

Among them, l is the total length of the gear distance, and K is the correction coefficient in this state.

The result unit 302 is configured to correct the double-terminal ranging formula according to the determined correction coefficient, calculate the corrected value of the fault location, and determine the corrected fault point.

Preferably, the result unit 302 is used to correct the double-ended ranging formula according to the determined correction coefficient, calculate the corrected value of the fault location, and determine the corrected fault point, including:

Among them, K is the correction coefficient in this state, l is the total length of the span line, L _M is the distance from the fault point to the end point of M, v is the traveling wave velocity, and _t1 is the initial traveling wave from the fault point to the first end of the wire The elapsed time of M, _t2 is the elapsed time for the initial traveling wave to reach the second end N of the conductor from the fault point.

A traveling wave distance measuring system 300 in a preferred embodiment of the present invention that considers changes in line length corresponds to a traveling wave distance measuring method 100 in a preferred embodiment of the present invention that considers changes in line length, and will not be repeated here .

The invention has been described with reference to a small number of embodiments. However, it is clear to a person skilled in the art that other embodiments than the invention disclosed above are equally within the scope of the invention, as defined by the appended patent claims.

Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise therein. All references to "a//the [device, component, etc.]" are openly construed to mean at least one instance of the device, component, etc., unless expressly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

Claims (12)

1. A traveling wave ranging method that accounts for line length variations, the method comprising:

calculating allowable stress and specific load of the conductor based on conductor parameters, span, annual weather and environmental conditions and tower installation parameters of the conductor in the target power transmission line;

calculating the critical span of the wire based on the allowable stress and the specific load of the wire;

calculating the actual line length of the target gear span under any current condition based on the critical gear span and the line state equation, repeatedly calculating the actual line length of each gear span and accumulating to obtain the actual line total length;

calculating a correction coefficient under a corresponding condition based on the actual line total length;

and correcting the double-end distance measurement formula according to the determined correction coefficient, calculating a fault position correction value, and determining a corrected fault point.

2. The method of claim 1, the wire parameters comprising: rated valueBreaking force T _N Elastic modulus E, linear expansion coefficient alpha, sectional area A, unit length q of overhead line, diameter d of stranded wire, design safety coefficient k of overhead line and size coefficient mu of overhead line _sc ；

The gear span comprises a plurality of gear spans from 100 to 1000 m;

the annual weather and environmental conditions include: average temperature, highest temperature, lowest temperature, maximum ice coating thickness and temperature, maximum wind speed and wind speed non-uniformity coefficient alpha of each season _f And an overhead line wind load adjustment coefficient beta _c ；

The tower installation parameters comprise: height difference and height difference angle.

3. The method of claim 1, the calculating a wire allowable stress, comprising:

wherein σ _p The design safety factor of k being the overhead line is 2.5 for the tensile strength of the overhead line, and the comprehensive breaking force T _P Is 95% of rated breaking force T _N A is the sectional area of the wire, T _N Rated breaking force [ sigma ] for the wire]Allowing stress for the wire.

4. The method of claim 1, the comparing, comprising: specific gravity load of gamma ₁ Specific ice weight gamma ₂ Vertical total specific load gamma ₃ No ice wind pressure specific load gamma ₄ Specific load gamma of wind pressure coated with ice ₅ And no ice comprehensive specific load gamma ₆ And icing comprehensive specific load gamma ₇ 。

5. The method of claim 1, wherein calculating the actual line length of the target range at any current condition based on the critical range and the line state equation:

wherein L is the actual length of the lead wire, L _x Is the span length, sigma ₀ The horizontal stress of the lead is adopted, beta is a high angle difference, cos beta is a high difference angle cosine value, and gamma is a specific load;

repeating the above calculation process to calculate the actual line length l of each span of the target line _x According to the actual line length l of each span _x Accumulating to obtain the actual total length L of the line;

based on the actual line full length, calculating a correction coefficient under corresponding conditions:

wherein l is the total length of the span line, and K is the correction coefficient in this state.

6. The method of claim 1, wherein said modifying the double ended ranging equation based on the determined modification factor to calculate a fault location modification value to determine a modified fault point comprises:

where K is the correction factor in this state, L is the span line length, L _M Is the distance from the fault point to the M end point, v is the traveling wave velocity, t ₁ The time, t, of the initial traveling wave from the fault point to the first end M of the conductor ₂ The time that the initial traveling wave has passed from the fault point to the second end N of the conductor.

7. A traveling wave ranging system that accounts for line length variations, the system comprising:

the calculation unit is used for calculating the allowable stress and specific load of the lead based on lead parameters, span, annual weather and environmental conditions and pole and tower installation parameters of the lead in the target power transmission line; calculating the critical span of the wire based on the allowable stress and the specific load of the wire; calculating the actual line length of the target span under any current condition based on the critical span and the line state equation, repeatedly calculating the actual line length of each span and accumulating to obtain the actual line total length; calculating a correction coefficient under a corresponding condition based on the actual line total length;

and the result unit is used for correcting the double-end distance measurement formula according to the determined correction coefficient, calculating a fault position correction value and determining a corrected fault point.

8. The system of claim 7, the lead parameters comprising: rated breaking force T _N Elastic modulus E, linear expansion coefficient alpha, sectional area A, unit length q of overhead line, stranded wire diameter d, overhead line design safety coefficient k and body type coefficient mu of overhead line _sc ；

The gear span comprises a plurality of gear spans from 100 to 1000 m;

the annual weather and environmental conditions include: average temperature, highest temperature, lowest temperature, maximum ice coating thickness and temperature, maximum wind speed and wind speed non-uniformity coefficient alpha of each season _f Air load adjustment coefficient beta of overhead line _c ；

The tower installation parameters comprise: height difference and height difference angle.

9. The system of claim 7, the calculating a wire allowable stress, comprising:

wherein,σ _p the design safety factor of k for the overhead line is 2.5, and the comprehensive breaking force T is _P Is 95% of rated breaking force T _N A is the sectional area of the wire, T _N Rated breaking force [ sigma ] for the wire]Allowing stress for the wire.

10. The system of claim 7, the comparing, comprising: specific gravity load of gamma ₁ Specific ice weight gamma ₂ Vertical total specific load gamma ₃ No ice wind pressure specific load gamma ₄ And specific loading gamma of ice-coated wind pressure ₅ Comprehensive specific load gamma without ice ₆ And icing comprehensive specific load gamma ₇ 。

11. The system of claim 7, wherein the actual line length for the target range at any current condition is calculated based on the critical range and a line state equation:

wherein L is the actual line length of the lead wire L _x For the length of span line, σ ₀ The horizontal stress of the lead is adopted, beta is a high angle difference, cos beta is a high difference angle cosine value, and gamma is a specific load;

repeating the above calculation process to calculate the actual line length l of each span of the target line _x According to the actual line length l of each span _x Accumulating to obtain the actual total length L of the line; based on the actual total line length of the route, calculating a correction coefficient under a corresponding condition:

wherein l is the total length of the span line, and K is the correction coefficient in the state.

12. The system of claim 7, the results unit to correct the double ended ranging equation based on determining a correction factor, calculate a fault location correction value, and determine a corrected fault point, comprising:

wherein K is the correction coefficient in the state, L is the total span of the span line, L _M Is the distance from the fault point to the M end point, v is the traveling wave velocity, t ₁ The time, t, of the initial traveling wave from the fault point to the first end M of the conductor ₂ The time that the initial traveling wave has passed from the fault point to the second end N of the conductor.

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