阅读说明：本技术 一种耐张塔输电线路等值覆冰厚度测量方法及系统 (Method and system for measuring equivalent icing thickness of power transmission line of strain tower ) 是由 马晓红 牛唯 毛先胤 黄欢 杨旗 文屹 黄增浩 李�昊 何锦强 赵林杰 廖永力 于 2021-07-26 设计创作，主要内容包括：本发明公开了一种耐张塔输电线路等值覆冰厚度测量方法及系统,包括建立输电线路的有限元仿真模型,获得无覆冰工况下耐张段首尾端的第一耐张串轴向张力和第二耐张串轴向张力；向有限元仿真模型施加覆冰荷载,获得对应的第三耐张串轴向张力和第四耐张串轴向张力；当第一拉力监测值大于第一耐张串轴向张力,且第二拉力监测值大于第二耐张串轴向张力时,计算输电线路的第一等值覆冰厚度和第二等值覆冰厚度；基于第一等值覆冰厚度、第二等值覆冰厚度与覆冰厚度理论值的比较结果确定拉力传感器的布置位置,采用称重法计算最终等值覆冰厚度。本发明能够减小覆冰厚度计算结果的误差,从而提高输电线路覆冰监测准确度。(The invention discloses a method and a system for measuring equivalent icing thickness of a tension tower power transmission line, which comprises the steps of establishing a finite element simulation model of the power transmission line, and obtaining a first tension string axial tension and a second tension string axial tension of the head end and the tail end of a tension section under the working condition without icing; applying an icing load to the finite element simulation model to obtain corresponding third tension string axial tension and fourth tension string axial tension; when the first tension monitoring value is larger than the axial tension of the first tension string and the second tension monitoring value is larger than the axial tension of the second tension string, calculating the first equivalent icing thickness and the second equivalent icing thickness of the power transmission line; and determining the arrangement position of the tension sensor based on the comparison results of the first equivalent icing thickness, the second equivalent icing thickness and the theoretical icing thickness value, and calculating the final equivalent icing thickness by adopting a weighing method. The method and the device can reduce the error of the ice coating thickness calculation result, thereby improving the ice coating monitoring accuracy of the power transmission line.)

1. A strain tower power transmission line equivalent icing thickness measuring method is characterized by comprising the following steps:

establishing a finite element simulation model of the power transmission line, and obtaining a first strain insulator-string axial tension at the head end of the strain section and a second strain insulator-string axial tension at the tail end of the strain section under the ice-coating-free working condition;

applying an icing load with a preset icing thickness theoretical value to the finite element simulation model to obtain a third tension string axial tension at the head end and a fourth tension string axial tension at the tail end corresponding to the preset icing thickness theoretical value;

when a first tension monitoring value monitored by a first tension sensor arranged on the tension tower at the head end is larger than the axial tension of the first tension string, and a second tension monitoring value monitored by a second tension sensor arranged on the tension tower at the tail end is larger than the axial tension of the second tension string, calculating to obtain a first equivalent ice coating thickness of the power transmission line according to the axial tension of the first tension string and the axial tension of the third tension string, and calculating to obtain a second equivalent ice coating thickness of the power transmission line according to the axial tension of the second tension string and the axial tension of the fourth tension string;

and determining the arrangement position of the tension sensor based on the comparison result of the first equivalent icing thickness, the second equivalent icing thickness and the theoretical icing thickness value, and calculating by adopting a weighing method to obtain the final equivalent icing thickness of the power transmission line.

2. The method for measuring equivalent icing thickness of a tension tower power transmission line according to claim 1, wherein after the arrangement position of the tension sensor is determined based on the comparison result of the first equivalent icing thickness, the second equivalent icing thickness and the theoretical value of the icing thickness, the method further comprises:

according to the arrangement position, arranging a third tension sensor on the tension tower at the head end or the tension tower at the tail end;

obtaining a fifth tension string axial tension under the ice-coating-free working condition according to the finite element simulation model;

applying a plurality of ice coating loads with uniform ice coating or non-uniform ice coating to the finite element simulation model to obtain a plurality of corresponding second tension string axial tensions, and drawing a scatter diagram of ice coating thickness-tension string axial tensions;

acquiring a curve fitting formula about the ice coating thickness and the axial tension of the strain insulator string by adopting a data fitting method according to the scatter diagram;

and when a third tension monitoring value monitored by a third tension sensor is larger than the axial tension of the fifth strain insulator-string, substituting the third tension monitoring value into the curve fitting formula to obtain the final equivalent icing thickness of the power transmission line.

3. The method of claim 1, wherein in the finite element simulation model, the ice coating load is equivalently simulated by applying a concentration force to the node along the line, wherein the concentration force is calculated according to the following formula:

ω＝0.9πgb(b+D)×10^-3

T＝ωL＝[0.9πgb(b+D)×10^-3]L

wherein D is the outer diameter of the transmission line, b is the thickness of the ice coating, g is the acceleration of gravity, omega is the gravity of the unit length of the transmission line, L is the length of the finite element unit, and T is the magnitude of the concentration force applied to the finite element simulation model.

4. The method for measuring equivalent icing thickness of a tension tower power transmission line according to claim 1, wherein the step of calculating the first equivalent icing thickness of the power transmission line according to the axial tension of the first tension string and the axial tension of the third tension string comprises the following steps:

calculating to obtain a first equivalent length of the power transmission line according to the axial tension of the first strain insulator-string:

in the formula, F₀₁Is the axial tension of the first strain insulator-string, n₀Is the number of power transmission line splits, omega₀The weight is the unit length weight of the transmission line, and theta is the included angle of the insulator string;

calculating to obtain a first maximum equivalent length of the power transmission line according to the axial tension of the first strain insulator-string:

in the formula, F₀₁Is the axial tension of the first strain insulator-string, n₀Is the number of power transmission line splits, omega₀The weight is the unit length weight of the transmission line, and theta is the included angle of the insulator string;

calculating to obtain a first equivalent ice thickness of the power transmission line according to the first equivalent length, the first maximum equivalent length and the third tension string axial tension:

in the formula, F₁Is the axial tension, omega, of the third strain insulator-string₀Is the weight per unit length of the transmission line, n₀Is the number of splits of the transmission line, D is the outer diameter of the transmission line, l_av1Is the first equivalent length,/_max1Is the first maximum equivalent length.

5. The method for measuring equivalent icing thickness of a tension tower power transmission line according to claim 1, wherein the step of calculating the second equivalent icing thickness of the power transmission line according to the second tension string axial tension and the fourth tension string axial tension comprises the following steps:

calculating according to the axial tension of the second strain insulator-string to obtain a second equivalent length of the power transmission line:

in the formula, F₀₂Is the axial tension of the second strain insulator-string, n₀Is the number of power transmission line splits, omega₀The weight is the unit length weight of the transmission line, and theta is the included angle of the insulator string;

calculating to obtain a second maximum equivalent length of the power transmission line according to the axial tension of the second strain insulator-string:

in the formula, F₀₂Is the axial tension of the second strain insulator-string, n₀Is the number of power transmission line splits, omega₀The weight is the unit length weight of the transmission line, and theta is the included angle of the insulator string;

calculating to obtain a second equivalent ice thickness of the power transmission line according to the second equivalent length, the second maximum equivalent length and the fourth tension string axial tension:

in the formula, F₂Is the fourth strain insulator-string axial tension, omega₀Is the weight per unit length of the transmission line, n₀Is the number of splits of the transmission line, D is the outer diameter of the transmission line, l_av2For said second equivalent length,/_max2Is the second maximum equivalent length.

6. The equivalent icing thickness measuring method for the tension tower power transmission line according to claim 2, wherein the step of drawing a scatter diagram of icing thickness-tension string axial tension comprises the following steps:

when the icing load is uneven icing, the icing thickness of the scatter diagram is the average icing thickness of the strain section;

calculating the average ice coating thickness according to a preset first formula, or calculating the average ice coating thickness according to a preset second formula;

the first formula is:

in the first formula, b_iIs the ice coating thickness of the i-th gear, S_iIs the length of the transmission line in the i-th gear,the average ice coating thickness of the strain section;

the second formula is:

in the second formula, b_iThe thickness of ice coating of the i-th gear,/_iThe length of the i-th gear span is,the average ice coating thickness of the strain section.

7. The utility model provides a strain insulator tower transmission line equivalence icing thickness measurement system which characterized in that includes:

establishing a simulation model module for establishing a finite element simulation model of the power transmission line to obtain a first strain insulator-string axial tension at the head end of the strain section and a second strain insulator-string axial tension at the tail end of the strain section under the ice-coating-free working condition;

an icing load applying module for applying an icing load with a preset icing thickness theoretical value to the finite element simulation model to obtain a third tension string axial tension at the head end and a fourth tension string axial tension at the tail end corresponding to the preset icing thickness theoretical value;

the first calculation module is used for calculating to obtain a first equivalent ice coating thickness of the power transmission line according to the first tension string axial tension and the third tension string axial tension when a first tension monitoring value monitored by a first tension sensor arranged on the tension tower at the head end is larger than the first tension string axial tension and a second tension monitoring value monitored by a second tension sensor arranged on the tension tower at the tail end is larger than the second tension string axial tension, and calculating to obtain a second equivalent ice coating thickness of the power transmission line according to the second tension string axial tension and the fourth tension string axial tension;

and the second calculation module is used for determining the arrangement position of the tension sensor based on the comparison result of the first equivalent icing thickness, the second equivalent icing thickness and the theoretical icing thickness value, and calculating by adopting a weighing method to obtain the final equivalent icing thickness of the power transmission line.

Technical Field

The invention relates to the field of monitoring of ice coating of a power transmission line, in particular to a method and a system for measuring equivalent ice coating thickness of a tension tower power transmission line.

Background

The ice coating of the power transmission line seriously affects the safe and stable operation of the power grid, and the occurrence of extreme weather conditions causes the frequent occurrence of large-area ice coating events of the power transmission line, so that accidents such as disconnection, conductor galloping, tower collapse, insulator flashover and the like of the power transmission line occur, and huge economic and property losses are caused to power grid departments. Because the icing brings great harm, the monitoring of the icing of the power transmission line is more and more urgent. The weighing method is widely applied to domestic power grid icing monitoring due to simple principle and mature technology, and gradually becomes an industrial standard. The tension sensor is a key device applied to the weighing method, and the error between the ice coating calculation result and the actual value is larger due to the non-standardization of the installation position of the tension sensor, so that the accuracy of the ice coating monitoring result is influenced.

Disclosure of Invention

The invention provides a method and a system for measuring equivalent icing thickness of a tension tower power transmission line, which are used for solving the problem that the error between an icing calculation result and an actual value is larger in the prior art.

The embodiment of the invention provides a method for measuring equivalent icing thickness of a tension tower power transmission line, which comprises the following steps:

establishing a finite element simulation model of the power transmission line, and obtaining a first strain insulator-string axial tension at the head end of the strain section and a second strain insulator-string axial tension at the tail end of the strain section under the ice-coating-free working condition;

applying an icing load with a preset icing thickness theoretical value to the finite element simulation model to obtain a third tension string axial tension at the head end and a fourth tension string axial tension at the tail end corresponding to the preset icing thickness theoretical value;

when a first tension monitoring value monitored by a first tension sensor arranged on the tension tower at the head end is larger than the axial tension of the first tension string, and a second tension monitoring value monitored by a second tension sensor arranged on the tension tower at the tail end is larger than the axial tension of the second tension string, calculating to obtain a first equivalent ice coating thickness of the power transmission line according to the axial tension of the first tension string and the axial tension of the third tension string, and calculating to obtain a second equivalent ice coating thickness of the power transmission line according to the axial tension of the second tension string and the axial tension of the fourth tension string;

and determining the arrangement position of the tension sensor based on the comparison result of the first equivalent icing thickness, the second equivalent icing thickness and the theoretical icing thickness value, and calculating by adopting a weighing method to obtain the final equivalent icing thickness of the power transmission line.

Further, after determining the arrangement position of the tension sensor based on the comparison result of the first equivalent icing thickness, the second equivalent icing thickness and the theoretical icing thickness value, the method further includes:

according to the arrangement position, arranging a third tension sensor on the tension tower at the head end or the tension tower at the tail end;

obtaining a fifth tension string axial tension under the ice-coating-free working condition according to the finite element simulation model;

applying a plurality of ice coating loads with uniform ice coating or non-uniform ice coating to the finite element simulation model to obtain a plurality of corresponding second tension string axial tensions, and drawing a scatter diagram of ice coating thickness-tension string axial tensions;

acquiring a curve fitting formula about the ice coating thickness and the axial tension of the tension string by adopting a data fitting method according to the scatter diagram;

and when a third tension monitoring value monitored by a third tension sensor is larger than the axial tension of the fifth strain insulator-string, substituting the third tension monitoring value into the curve fitting formula to obtain the final equivalent icing thickness of the power transmission line.

Further, in the finite element simulation model, equivalently simulating an icing load by applying a concentrated force to the nodes along the line, wherein the concentrated force is calculated according to the following formula:

ω＝0.9πgb(b+D)×10^-3

T＝ωL＝[0.9πgb(b+D)×10^-3]L

wherein D is the outer diameter of the transmission line, b is the thickness of the ice coating, g is the acceleration of gravity, omega is the gravity of the unit length of the transmission line, L is the length of the finite element unit, and T is the magnitude of the concentration force applied to the finite element simulation model.

Further, the calculating the first equivalent icing thickness of the power transmission line according to the first tension string axial tension and the third tension string axial tension includes:

calculating to obtain a first equivalent length of the power transmission line according to the axial tension of the first strain insulator-string:

in the formula, F₀₁Is the axial tension of the first strain insulator-string, n₀Is the number of power transmission line splits, omega₀The unit length weight of the power transmission line is shown, and theta is an included angle of the insulator string;

calculating to obtain a first maximum equivalent length of the power transmission line according to the axial tension of the first strain insulator-string:

in the formula, F₀₁Is the axial tension of the first strain insulator-string, n₀Is the number of power transmission line splits, omega₀The unit length weight of the power transmission line is shown, and theta is an included angle of the insulator string;

calculating to obtain a first equivalent ice thickness of the power transmission line according to the first equivalent length, the first maximum equivalent length and the third strain insulator-string axial tension:

in the formula, F₁Is the axial tension, omega, of the third strain insulator-string₀Is the weight per unit length of the transmission line, n₀Is the number of power transmission line splits, D is the outer diameter of the power transmission line, l_av1Is the first equivalent length,/_max1Is the firstThe maximum equivalent length.

Further, the calculating the second equivalent icing thickness of the power transmission line according to the second tension string axial tension and the fourth tension string axial tension includes:

calculating to obtain a second equivalent length of the power transmission line according to the axial tension of the second strain insulator-string:

in the formula, F₀₂Is the axial tension of the second strain insulator-string, n₀Is the number of power transmission line splits, omega₀The unit length weight of the power transmission line is shown, and theta is an included angle of the insulator string;

calculating to obtain a second maximum equivalent length of the power transmission line according to the axial tension of the second strain insulator-string:

in the formula, F₀₂Is the axial tension of the second strain insulator-string, n₀Is the number of power transmission line splits, omega₀The unit length weight of the power transmission line is shown, and theta is an included angle of the insulator string;

calculating to obtain a second equivalent ice thickness of the power transmission line according to the second equivalent length, the second maximum equivalent length and the fourth strain insulator-string axial tension:

in the formula, F₂Is the fourth strain insulator-string axial tension, omega₀Is the weight per unit length of the transmission line, n₀Is the number of power transmission line splits, D is the outer diameter of the power transmission line, l_av2For said second equivalent length,/_max2Is the second maximum equivalent length.

Further, the drawing of the scatter diagram of ice coating thickness-strain insulator-string axial tension includes:

when the icing load is uneven icing, the icing thickness of the scatter diagram is the average icing thickness of the strain section;

calculating the average ice coating thickness according to a preset first formula, or calculating the average ice coating thickness according to a preset second formula;

the first formula is:

in the first formula, b_iIs the ice coating thickness of the i-th gear, S_iIs the length of the transmission line in the i-th gear,the average ice coating thickness of the strain section;

the second formula is:

in the second formula, b_iThe thickness of ice coating of the i-th gear,/_iThe length of the i-th gear span is,the average ice coating thickness of the strain section.

Correspondingly, the embodiment of the invention also provides a strain tower power transmission line equivalent icing thickness measuring system, which comprises:

establishing a simulation model module for establishing a finite element simulation model of the power transmission line to obtain a first strain insulator-string axial tension at the head end of the strain section and a second strain insulator-string axial tension at the tail end of the strain section under the ice coating-free working condition;

an icing load applying module for applying an icing load with a preset icing thickness theoretical value to the finite element simulation model to obtain a third tension string axial tension at the head end and a fourth tension string axial tension at the tail end corresponding to the preset icing thickness theoretical value;

the first calculation module is used for calculating to obtain a first equivalent icing thickness of the power transmission line according to the first tension string axial tension and the third tension string axial tension and calculating to obtain a second equivalent icing thickness of the power transmission line according to the second tension string axial tension and the fourth tension string axial tension when a first tension monitoring value monitored by a first tension sensor arranged on the tension tower at the head end is larger than the first tension string axial tension and a second tension monitoring value monitored by a second tension sensor arranged on the tension tower at the tail end is larger than the second tension string axial tension;

and the second calculation module is used for determining the arrangement position of the tension sensor based on the comparison result of the first equivalent icing thickness, the second equivalent icing thickness and the theoretical icing thickness value, and calculating to obtain the final equivalent icing thickness of the power transmission line by adopting a weighing method.

Compared with the prior art, the strain tower power transmission line equivalent icing thickness measuring method and system provided by the embodiment of the invention have the advantages that the strain string axial tension at the head end and the tail end of the strain section under the working condition without icing is obtained by establishing the finite element simulation model, the icing load with the preset icing thickness theoretical value is applied to the finite element simulation model, the corresponding strain string axial tension at the head end and the tail end of the strain section is obtained, the first equivalent icing thickness and the second equivalent icing thickness are obtained through calculation according to the strain string axial tension, the arrangement position of the tension sensor is determined based on the comparison result of the first equivalent icing thickness, the second equivalent icing thickness and the icing thickness theoretical value, and the final equivalent icing thickness of the power transmission line is obtained through calculation by adopting a weighing method. According to the embodiment of the invention, the equivalent icing thickness is obtained through the axial tension calculation of the strain insulator-string, and is compared with the preset icing thickness theoretical value, the arrangement position of the tension sensor is determined, and the error of the icing thickness calculation result is reduced, so that the icing monitoring accuracy of the power transmission line is improved, and the early warning and the false alarm of an icing monitoring system are avoided.

Drawings

FIG. 1 is a schematic flow chart of a method for measuring equivalent icing thickness of a tension tower power transmission line provided by an embodiment of the invention;

FIG. 2 is a schematic structural diagram of an equivalent icing thickness measuring system for a tension tower power transmission line according to an embodiment of the invention;

fig. 3 is a model diagram of a power transmission line with a tension resistant section of "three towers and two gears" in which a tension resistant tower is located according to an embodiment of the present invention.

Fig. 4 is an ice coating thickness-strain insulator-string axial tension scatter diagram provided by an embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1, which is a schematic flow chart of a method for measuring equivalent icing thickness of a tension tower power transmission line provided in an embodiment of the present invention, the method includes:

s11, establishing a finite element simulation model of the power transmission line, and obtaining a first strain insulator-string axial tension at the head end of the strain section and a second strain insulator-string axial tension at the tail end of the strain section under the ice-coating-free working condition;

specifically, a finite element simulation model of the power transmission line is established through the following steps:

selecting a proper finite element unit type by combining the structural characteristics of the power transmission line, and determining the real constant and the material property of the finite element unit type; determining the initial form of the transmission line based on a direct iteration method, and solving the structural shape meeting the prestress state and the boundary condition; and modeling the insulator string, and establishing a power transmission line-insulator string coupling model. The upper end of the suspension string is fixed, the lower end of the suspension string is hinged with the power transmission line, and the connection point of the suspension string and the power transmission line can move; setting an icing load according to the simulation working condition; specifying constraint conditions, defining analysis types, load data and load step options, opening a large deformation switch, and carrying out finite element solution; and a finite element solution result post-processing part defines an axial tension unit table, lists and displays the axial tension of the units, and extracts the axial tension of the strain insulator-string according to the unit numbers. It can be understood that static force is not applied to the finite element simulation model, and the axial tension of the tension string under the ice-coating-free working condition is obtained through finite element solution.

S12, applying an icing load with a preset icing thickness theoretical value to the finite element simulation model to obtain a third tension string axial tension at the head end and a fourth tension string axial tension at the tail end corresponding to the preset icing thickness theoretical value;

it can be understood that the icing load of the preset icing thickness theoretical value is equivalently converted into a concentrated force, the concentrated force is applied to a finite element simulation model, and the axial tension of the third tension string at the head end and the axial tension of the fourth tension string at the tail end corresponding to the preset icing thickness theoretical value are obtained through finite element solution.

S13, when a first tension monitoring value monitored by a first tension sensor mounted on the tension tower at the head end is larger than the axial tension of the first tension string and a second tension monitoring value monitored by a second tension sensor mounted on the tension tower at the tail end is larger than the axial tension of the second tension string, calculating to obtain a first equivalent icing thickness of the power transmission line according to the axial tension of the first tension string and the axial tension of the third tension string, and calculating to obtain a second equivalent icing thickness of the power transmission line according to the axial tension of the second tension string and the axial tension of the fourth tension string;

it can be understood that when the first tension monitoring value is not greater than the first tension string axial tension, or the second tension monitoring value is not greater than the second tension string axial tension, the equivalent ice coating thickness of the power transmission line is 0;

s14, determining the arrangement position of the tension sensor based on the comparison result of the first equivalent icing thickness, the second equivalent icing thickness and the theoretical icing thickness value, and calculating by adopting a weighing method to obtain the final equivalent icing thickness of the transmission line.

In particular, the icing thickness b is based on the first equivalence value₁The second equivalent ice coating thickness b₂And the theoretical value b of the ice coating thickness₀Determining the arrangement position of the tension sensor according to the comparison result:

when | b₁-b₀|＜|b₂-b₀When the tension sensor is arranged on the tension tower at the head end of the tension section;

when | b₁-b₀|＞|b₂-b₀When the tension sensor is arranged on the tension tower at the tail end of the tension section;

when | b₁-b₀|＝|b₂-b₀When |, the tension sensor is arranged on the tension tower at the head end of the tension section or the tension tower at the tail end of the tension section.

In another optional embodiment, after the determining the arrangement position of the tension sensor based on the comparison result of the first equivalent icing thickness, the second equivalent icing thickness and the theoretical value of icing thickness, the method further comprises:

according to the arrangement position, arranging a third tension sensor on the tension tower at the head end or the tension tower at the tail end;

obtaining a fifth tension string axial tension under the ice-coating-free working condition according to the finite element simulation model;

applying a plurality of ice coating loads with uniform ice coating or non-uniform ice coating to the finite element simulation model to obtain a plurality of corresponding second tension string axial tensions, and drawing a scatter diagram of ice coating thickness-tension string axial tensions;

acquiring a curve fitting formula about the ice coating thickness and the axial tension of the tension string by adopting a data fitting method according to the scatter diagram;

specifically, the distribution characteristics of data points in a rectangular plane coordinate system are analyzed, the variation trend of the icing thickness along with the axial tension of the strain insulator-string is grasped, the correlation coefficient of the icing thickness and the axial tension of the strain insulator-string is calculated, the degree of closeness of the correlation between the two variables is characterized, and the expression of the correlation coefficient is

Wherein x is_iFor the ith strain insulator-string axial tension data, y_iAs the ith ice coating thickness data,the average value of the axial tension data of the tension string is obtained,the average of the ice coating thickness data is obtained, and n is the total number of data points.

According to the correlation coefficient, combining the distribution of discrete points in the scatter diagram, selecting a proper function type to fit the data points, wherein the selected function type is an elementary function as much as possible, and the simplicity of a curve fitting formula is ensured;

and when a third tension monitoring value monitored by a third tension sensor is larger than the axial tension of the fifth strain insulator-string, substituting the third tension monitoring value into the curve fitting formula to obtain the final equivalent icing thickness of the power transmission line.

Specifically, when the third tension monitoring value is not greater than the fifth tension string axial tension, the equivalent ice coating thickness of the power transmission line is 0; when the third tension monitoring value is larger than the fifth tension string axial tension, substituting the third tension monitoring value into the curve fitting formula to obtain the final equivalent icing thickness of the power transmission line

In the embodiment of the invention, the axial tension of the tension string corresponding to the icing thickness is obtained through finite element simulation, and a curve fitting formula of the icing thickness and the axial tension of the tension string is obtained through derivation, so that the equivalent icing thickness of the tension tower power transmission line is realized, and the simplicity of the calculation method of the icing of the power transmission line is improved.

As an improvement of the above scheme, in the finite element simulation model, an icing load is equivalently simulated by applying a concentration force to a node along a line, wherein the concentration force is calculated according to the following formula:

ω＝0.9πgb(b+D)×10^-3

T＝ωL＝[0.9πgb(b+D)×10^-3]L

wherein D is the outer diameter of the transmission line, b is the thickness of the ice coating, g is the acceleration of gravity, omega is the gravity of the unit length of the transmission line, L is the length of the finite element unit, and T is the magnitude of the concentration force applied to the finite element simulation model.

As an improvement of the above scheme, the calculating the first equivalent ice thickness of the power transmission line according to the first tension string axial tension and the third tension string axial tension includes:

calculating to obtain a first equivalent length of the power transmission line according to the axial tension of the first strain insulator-string:

in the formula, F₀₁Is the axial tension of the first strain insulator-string, n₀Is the number of power transmission line splits, omega₀The unit length weight of the power transmission line is shown, and theta is an included angle of the insulator string;

calculating to obtain a first maximum equivalent length of the power transmission line according to the axial tension of the first strain insulator-string:

in the formula, F₀₁Is the axial tension of the first strain insulator-string, n₀Is the number of power transmission line splits, omega₀The unit length weight of the power transmission line is shown, and theta is an included angle of the insulator string;

calculating to obtain a first equivalent ice thickness of the power transmission line according to the first equivalent length, the first maximum equivalent length and the third strain insulator-string axial tension:

in the formula, F₁Is the axial tension, omega, of the third strain insulator-string₀Is the weight per unit length of the transmission line, n₀Is the number of power transmission line splits, D is the outer diameter of the power transmission line, l_av1Is the first equivalent length,/_max1Is the first maximum equivalent length.

As an improvement of the above-mentioned scheme, the calculating the second equivalent ice thickness of the power transmission line according to the second tension string axial tension and the fourth tension string axial tension includes:

calculating to obtain a second equivalent length of the power transmission line according to the axial tension of the second strain insulator-string:

in the formula, F₀₂Is the axial tension of the second strain insulator-string, n₀Is the number of power transmission line splits, omega₀The unit length weight of the power transmission line is shown, and theta is an included angle of the insulator string;

calculating to obtain a second maximum equivalent length of the power transmission line according to the axial tension of the second strain insulator-string:

in the formula, F₀₂Is the axial tension of the second strain insulator-string, n₀Is the number of power transmission line splits, omega₀The unit length weight of the power transmission line is shown, and theta is an included angle of the insulator string;

calculating to obtain a second equivalent ice thickness of the power transmission line according to the second equivalent length, the second maximum equivalent length and the fourth strain insulator-string axial tension:

in the formula, F₂Is the fourth strain insulator-string axial tension, omega₀Is the weight per unit length of the transmission line, n₀Is the number of power transmission line splits, D is the outer diameter of the power transmission line, l_av2For said second equivalent length,/_max2Is the second maximum equivalent length.

As an improvement of the above scheme, the plotting a scatter diagram of ice coating thickness-strain insulator-string axial tension includes:

when the icing load is uneven icing, the icing thickness of the scatter diagram is the average icing thickness of the strain section;

calculating the average ice coating thickness according to a preset first formula, or calculating the average ice coating thickness according to a preset second formula;

the first formula is:

in the first formula, b_iIs the ice coating thickness of the i-th gear, S_iIs the length of the transmission line in the i-th gear,the average ice coating thickness of the strain section;

the second formula is:

in the second formula, b_iThe thickness of ice coating of the i-th gear,/_iThe length of the i-th gear span is,the average ice coating thickness of the strain section.

It will be appreciated that for simplicity, the intra-span transmission line length may be replaced by the span length, and thus the average ice coating thickness may be calculated according to a preset second formula.

It should be noted that, in the embodiment of the present invention, for uneven icing, the axial tension of the strain insulator string under uneven icing is obtained by a finite element simulation method, the average icing thickness of the icing amount of the strain insulator segment is used to characterize the icing degree of the strain insulator segment during uneven icing, and a data set of the average icing thickness and the axial tension of the strain insulator string is established; calculating according to a preset first formula or a preset second formula to obtain the average ice coating thickness; for uniform ice coating, tension of the tension string corresponding to different ice coating thicknesses is obtained by changing the ice coating thickness, and the ice coating thickness is the average ice coating thickness;

and drawing a scatter diagram of the two variables of the average ice coating thickness and the axial tension of the strain insulator string in a planar rectangular coordinate system by taking the average ice coating thickness as a dependent variable and the axial tension of the strain insulator string as an independent variable.

In one embodiment, referring to fig. 3, the above method is applied to a 110kV transmission line, the designed ice thickness of the strain section is 30mm, the number of the split wires is 1, the type of the wire is JLHA1/G1A-185/30-26/7, the weight of the wire per unit length is 0.73kg/m, the outer diameter of the wire is 18.88mm, the weight of the insulator string is 150kg, the type of the insulator string is I-string, the included angle of the insulator string is 0, and the tension monitoring value monitored by the tension sensor at a certain moment is 1957 kg. Set the span length to be l₁＝150m，l₂196m, the height difference between the large-size side suspension point and the small-size side suspension point is h₁＝-40m，h₂＝50m。

Establishing a finite element simulation model of the power transmission line by using a finite element method and a full-size simulation method: according to the structural characteristics and the connection mode of the power transmission line and the insulator string, selecting a proper unit type for simulation, establishing a power transmission line-insulator string coupling model, determining the initial form of the power transmission line by adopting a direct iteration method, and equivalently simulating the icing load by applying a concentrated force simulation method. And (3) specifying constraint conditions, defining analysis types, load data and load step options, then carrying out finite element solution, and extracting the axial tension of the strain insulator-string.

Through finite element simulation calculation, the axial tension of the tension string under the working condition of no wind and no ice coating is 263 kg.

Respectively applying ice coating loads of uniform ice coating and non-uniform ice coating, and solving through finite elements to obtain corresponding tension string axial tension, wherein the axial tension is shown in the following table:

as can be seen from the above table, for the case of uniform icing, the case of uniform icing is simulated by applying icing loads with the same icing thickness to the large-size side span and the small-size side span, and five icing loads with different icing thicknesses of 5mm, 10mm, 15mm, 20mm, 25mm or 30mm are simultaneously applied to the large-size side span and the small-size side span for carrying out multiple simulation calculations, so as to obtain the corresponding axial tension of the tension string; for the condition of uneven icing, the condition of uneven icing is simulated by icing loads of different icing thicknesses of a large side gauge and a small side gauge tower gauge.

Drawing an ice coating thickness-strain insulator-string axial tension scatter diagram according to the finite element calculation result, as shown in fig. 4, wherein the ice coating thickness is in positive correlation with the strain insulator-string axial tension, the ice coating thickness is in linear relation with the strain insulator-string axial tension, and a correlation coefficient R is calculated²＝0.9313。

And according to the correlation coefficient, fitting by adopting a linear fitting mode, wherein the curve fitting formula is that b is 0.0185F-0.2089.

Since the tension monitoring value 1957kg is larger than the axial tension 263kg of the tension string under the working condition of no wind and no ice coating, the tension monitoring value 1957kg is substituted into a curve fitting formula b which is 0.0185F-0.2089, and the final equivalent ice coating thickness b of the power transmission line is obtained to be 36 mm.

Referring to fig. 2, a schematic structural diagram of an equivalent icing thickness measuring system for a tension tower power transmission line provided in an embodiment of the present invention includes:

establishing a simulation model module 21 for establishing a finite element simulation model of the power transmission line to obtain a first strain insulator-string axial tension at the head end of the strain section and a second strain insulator-string axial tension at the tail end of the strain section under the ice-coating-free working condition;

an icing load applying module 22, configured to apply an icing load with a preset theoretical value of icing thickness to the finite element simulation model, so as to obtain a third axial tension of the head end and a fourth axial tension of the tail end, which correspond to the preset theoretical value of icing thickness;

the first calculation module 23 is configured to calculate a first equivalent ice coating thickness of the power transmission line according to the first tension string axial tension and the third tension string axial tension when a first tension monitoring value monitored by a first tension sensor mounted on the tension tower at the head end is greater than the first tension string axial tension and a second tension monitoring value monitored by a second tension sensor mounted on the tension tower at the tail end is greater than the second tension string axial tension, and calculate a second equivalent ice coating thickness of the power transmission line according to the second tension string axial tension and the fourth tension string axial tension;

and the second calculating module 24 is configured to determine the arrangement position of the tension sensor based on a comparison result of the first equivalent icing thickness, the second equivalent icing thickness and the theoretical icing thickness value, and calculate the final equivalent icing thickness of the power transmission line by using a weighing method.

Preferably, the system further comprises:

the arrangement module is used for arranging a third tension sensor on the tension tower at the head end or the tension tower at the tail end according to the arrangement position;

the third calculation module is used for obtaining the fifth tension string axial tension under the ice-coating-free working condition according to the finite element simulation model;

the scatter diagram drawing module is used for applying a plurality of ice coating loads with uniform ice coating or non-uniform ice coating to the finite element simulation model to obtain a plurality of corresponding second tension string axial tensions and drawing a scatter diagram of ice coating thickness-tension string axial tensions;

the curve fitting module is used for acquiring a curve fitting formula about the ice coating thickness and the axial tension of the strain insulator string by adopting a data fitting method according to the scatter diagram;

and the fourth calculation module is used for substituting the third tension monitoring value into the curve fitting formula to obtain the final equivalent ice coating thickness of the power transmission line when the third tension monitoring value monitored by the third tension sensor is greater than the fifth tension string axial tension.

Preferably, in the finite element simulation model, the ice-coating load is equivalently simulated by applying a concentration force to the nodes along the line, wherein the concentration force is calculated according to the following formula:

ω＝0.9πgb(b+D)×10^-3

T＝ωL＝[0.9πgb(b+D)×10^-3]L

wherein D is the outer diameter of the transmission line, b is the thickness of the ice coating, g is the acceleration of gravity, omega is the gravity of the unit length of the transmission line, L is the length of the finite element unit, and T is the magnitude of the concentration force applied to the finite element simulation model.

Preferably, the first calculation module is further configured to:

calculating to obtain a first equivalent length of the power transmission line according to the axial tension of the first strain insulator-string:

in the formula, F₀₁Is the axial tension of the first strain insulator-string, n₀Is the number of power transmission line splits, omega₀The unit length weight of the power transmission line is shown, and theta is an included angle of the insulator string;

calculating to obtain a first maximum equivalent length of the power transmission line according to the axial tension of the first strain insulator-string:

in the formula, F₀₁Is the axial tension of the first strain insulator-string, n₀Is the number of power transmission line splits, omega₀The unit length weight of the power transmission line is shown, and theta is an included angle of the insulator string;

calculating to obtain a first equivalent ice thickness of the power transmission line according to the first equivalent length, the first maximum equivalent length and the third strain insulator-string axial tension:

in the formula, F₁Is the axial tension, omega, of the third strain insulator-string₀Is the weight per unit length of the transmission line, n₀Is the number of power transmission line splits, D is the outer diameter of the power transmission line, l_av1Is the first equivalent length,/_max1Is the first maximum equivalent length.

Preferably, the first calculation module is further configured to:

calculating to obtain a second equivalent length of the power transmission line according to the axial tension of the second strain insulator-string:

in the formula, F₀₂Is the axial tension of the second strain insulator-string, n₀Is the number of power transmission line splits, omega₀The unit length weight of the power transmission line is shown, and theta is an included angle of the insulator string;

calculating to obtain a second maximum equivalent length of the power transmission line according to the axial tension of the second strain insulator-string:

in the formula, F₀₂Is the second strain insulator-stringAxial tension, n₀Is the number of power transmission line splits, omega₀The unit length weight of the power transmission line is shown, and theta is an included angle of the insulator string;

calculating to obtain a second equivalent ice thickness of the power transmission line according to the second equivalent length, the second maximum equivalent length and the fourth strain insulator-string axial tension:

in the formula, F₂Is the fourth strain insulator-string axial tension, omega₀Is the weight per unit length of the transmission line, n₀Is the number of power transmission line splits, D is the outer diameter of the power transmission line, l_av2For said second equivalent length,/_max2Is the second maximum equivalent length.

Preferably, the scatter plot module is further configured to:

when the icing load is uneven icing, the icing thickness of the scatter diagram is the average icing thickness of the strain section;

calculating the average ice coating thickness according to a preset first formula, or calculating the average ice coating thickness according to a preset second formula;

the first formula is:

in the first formula, b_iIs the ice coating thickness of the i-th gear, S_iIs the length of the transmission line in the i-th gear,the average ice coating thickness of the strain section;

the second formula is:

in the second formula, b_iThe thickness of ice coating of the i-th gear,/_iThe length of the i-th gear span is,the average ice coating thickness of the strain section.

It should be noted that the equivalent icing thickness measurement system for the tension tower power transmission line provided by the embodiment of the present invention can implement all the processes of the equivalent icing thickness measurement method for the tension tower power transmission line described in any one of the above embodiments, and the functions and implemented technical effects of each unit and sub-unit in the system are respectively the same as those of the equivalent icing thickness measurement method for the tension tower power transmission line described in the above embodiment, and are not described herein again.

According to the method and the system for measuring the equivalent icing thickness of the tension tower power transmission line, the axial tension of the tension string at the head end and the tail end of the tension segment under the working condition without icing is obtained by establishing a finite element simulation model, the icing load with the preset icing thickness theoretical value is applied to the finite element simulation model, the axial tension of the tension string at the head end and the tail end of the corresponding tension segment is obtained, the first equivalent icing thickness and the second equivalent icing thickness are obtained through calculation according to the axial tension of the tension string, the arrangement position of the tension sensor is determined based on the comparison result of the first equivalent icing thickness, the second equivalent icing thickness and the icing thickness theoretical value, and the final equivalent icing thickness of the power transmission line is obtained through calculation by adopting a weighing method. According to the embodiment of the invention, the equivalent icing thickness is obtained through the calculation of the axial tension of the tension string and is compared with the preset icing thickness theoretical value, the arrangement position of the tension sensor is determined, and the error of the icing thickness calculation result is reduced, so that the icing monitoring accuracy of the power transmission line is improved, and an important technical support is provided for the icing monitoring and early warning of the power transmission line.

The foregoing is directed to the preferred embodiment of the present invention, and it is understood that various changes and modifications may be made by one skilled in the art without departing from the spirit of the invention, and it is intended that such changes and modifications be considered as within the scope of the invention.