CN113418629B - Inflection point temperature measuring method of carbon fiber composite core wire - Google Patents

Inflection point temperature measuring method of carbon fiber composite core wire Download PDF

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CN113418629B
CN113418629B CN202110715635.XA CN202110715635A CN113418629B CN 113418629 B CN113418629 B CN 113418629B CN 202110715635 A CN202110715635 A CN 202110715635A CN 113418629 B CN113418629 B CN 113418629B
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carbon fiber
fiber composite
composite core
core wire
inflection point
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CN113418629A (en
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杨长龙
许超
杨峰
沈佳熔
傅中原
郑洋
侯庭旸
张忠瑞
郑舒文
王勇
多俊龙
张洋
王晓娜
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State Grid Corp of China SGCC
Shanghai Electric Power University
Shenyang Power Supply Co of State Grid Liaoning Electric Power Co Ltd
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Shanghai Electric Power University
Shenyang Power Supply Co of State Grid Liaoning Electric Power Co Ltd
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Abstract

Discloses a method for measuring inflection point temperature of a carbon fiber composite core wire, wherein the method comprises the steps of measuring span L, height difference angle beta and initial temperature t of the carbon fiber composite core wire 0 Wherein, the carbon fiber composite core wire comprises a carbon fiber core and an aluminum alloy wire, the height difference angle beta is an included angle between the height difference between two suspension points of the same span L and the horizontal plane and is based on the span L, the height difference angle beta and the initial temperature t 0 Calculating the tension T of the carbon fiber composite core wire at the maximum sag point at the inflection point temperature C Based on the tension T of the carbon fiber composite core wire at the maximum sag point at the inflection point temperature C Generating the knee temperature t c 。

Description

Inflection point temperature measurement method of carbon fiber composite core wire
Technical Field
The invention relates to the technical field of carbon fiber composite core wires, in particular to a method for measuring inflection point temperature of a carbon fiber composite core wire.
Background
In recent years, with the rapid development of economy in China, the demand for electric power is continuously increased, the transmission capacity of the existing line is difficult to meet the increasing load demand, and the overload problem may cause power failure and power failure accidents, so that the demand for increasing capacity and modifying the existing line to relieve the contradiction between power supply and demand is urgent. The carbon fiber composite core conductor (ACCC) is used for replacing a traditional Aluminum Conductor Steel Reinforced (ACSR) cable, which is one of the measures of capacity increasing engineering of the power transmission line in China, and has a series of performance advantages of light weight, high strength, large current-carrying capacity, high temperature resistance, low sag and the like. The normal working temperature of the traditional steel-cored aluminum strand is only 70-80 ℃, and the difference between the thermal expansion coefficients of the steel core and the aluminum alloy wire is small, so that the steel core and the aluminum alloy wire are stressed simultaneously when the steel-cored aluminum strand works, but the temperature of the carbon fiber composite core wire can reach 200 ℃ when the carbon fiber composite core wire works normally, when the working temperature rises, and because the difference between the thermal expansion coefficients of the carbon fiber core and the aluminum alloy wire is large, the potential safety hazard can occur when the working temperature of the carbon fiber composite core wire rises, and a method for measuring the inflection point temperature in a non-contact manner is urgently needed in the field.
The above information disclosed in this background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is well known to those of ordinary skill in the art.
Disclosure of Invention
The invention aims to provide a method for measuring the inflection point temperature of a carbon fiber composite core wire. In order to achieve the above purpose, the invention provides the following technical scheme:
the invention discloses a method for measuring the inflection point temperature of a carbon fiber composite core wire, which comprises the following steps:
measuring span L, height difference angle beta and initial temperature t of carbon fiber composite core wire 0 Wherein the carbon fiber composite core lead comprises a carbon fiber core and an aluminum alloy wire, the height difference angle beta is an included angle between the height difference between two hanging points with the same span L and a horizontal plane, namely an included angle between a connecting line of the two hanging points and the horizontal plane,
based on the span L, the altitude difference angle beta and the initial temperature t 0 Calculating the tension T of the carbon fiber composite core wire at the maximum sag point at the inflection point temperature C Wherein, T C 3 +KT C 2 +N＝0
Figure BDA0003133968560000021
Figure BDA0003133968560000022
Figure BDA0003133968560000023
Wherein E represents the elastic modulus of the carbon fiber composite core wire, alpha and alpha a represent the thermal expansion coefficients of the carbon fiber composite core wire and the aluminum alloy wire respectively, and t 0 Representing the initial temperature, tc is the tension of the carbon fiber composite core wire at the maximum sag point at the inflection point temperature; a is the cross-sectional area of the carbon fiber composite core wire, beta is a height difference angle, L is a span, qm is the unit load of the wire at the maximum tension, tm is the maximum tension, tm is the temperature of the wire at the maximum tension, qc is the unit load of the wire at the inflection point temperature,
based on the tension T of the carbon fiber composite core wire at the maximum sag point at the inflection point temperature C Generating the knee temperature t c Wherein, in the step (A),
Figure BDA0003133968560000024
wherein E represents the elastic modulus of the carbon fiber composite core wire, tc is the tension of the carbon fiber composite core wire at the maximum sag point at the inflection point temperature, A is the cross-sectional area of the carbon fiber composite core wire, alpha and alpha a represent the thermal expansion coefficients of the carbon fiber composite core wire and the aluminum alloy wire respectively, t 0 Which represents the initial temperature of the molten steel,
in the inflection point temperature measurement method of the carbon fiber composite core wire, when the span of the carbon fiber composite core wire is a flat span, the height difference angle beta is 0.
In the technical scheme, the inflection point temperature measuring method of the carbon fiber composite core wire provided by the invention has the following beneficial effects: the traditional calculation mode can only calculate the inflection point temperature value under the condition of a flat span, and the method is not limited to the flat span and can realize the calculation of the inflection point temperature no matter whether the inclined span or the flat span is adopted.
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In order to more clearly illustrate the embodiments of the present application or technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments described in the present invention, and other drawings can be obtained by those skilled in the art according to the drawings.
Fig. 1 is a schematic layout view of a inflection point temperature measuring method of a carbon fiber composite core wire according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be obtained by a person skilled in the art without inventive efforts based on the embodiments of the present invention, are within the scope of protection of the present invention.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.
In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like, indicate orientations and positional relationships based on those shown in the drawings, and are used only for convenience of description and simplicity of description, and do not indicate or imply that the equipment or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be considered as limiting the present invention.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.
In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; they may be directly connected or indirectly connected through intervening media, or may be connected through the use of two elements or the interaction of two elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
In the present invention, unless expressly stated or limited otherwise, the recitation of a first feature "on" or "under" a second feature may include the recitation of the first and second features being in direct contact, and may also include the recitation that the first and second features are not in direct contact, but are in contact via another feature between them. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. "beneath," "under" and "beneath" a first feature includes the first feature being directly beneath and obliquely beneath the second feature, or simply indicating that the first feature is at a lesser elevation than the second feature.
In order to make those skilled in the art better understand the technical solution of the present invention, the present invention will be further described in detail with reference to the accompanying drawings.
As shown in fig. 1, fig. 1 shows that at an oblique span, the electric wire is approximately regarded as an oblique parabola, at the midpoint C, the maximum sag is, and Tc is the tension applied to the point C. The inflection point temperature measuring method of the carbon fiber composite core wire comprises the following steps of:
measuring span L, height difference angle beta and initial temperature t of carbon fiber composite core wire 0 Wherein the carbon fiber composite core lead comprises a carbon fiber core and an aluminum alloy wire, the height difference angle beta is an included angle between the height difference between two hanging points with the same span L and a horizontal plane, namely an included angle between a connecting line of the two hanging points and the horizontal plane,
calculating the tension T of the carbon fiber composite core wire at the maximum sag point at the inflection point temperature based on the span L, the height difference angle beta and the initial temperature T0 C Wherein, T C 3 +KT C 2 +N＝0，
Figure BDA0003133968560000041
Figure BDA0003133968560000042
Figure BDA0003133968560000045
Wherein E represents the elastic modulus of the carbon fiber composite core wire, alpha and alpha a represent the thermal expansion coefficients of the carbon fiber composite core wire and the aluminum alloy wire respectively, and t 0 Represents the initial temperature, tc is the tension of the carbon fiber composite core wire at the maximum sag point at the inflection point temperature; a is the cross-sectional area of the carbon fiber composite core wire, beta is the elevation angle, L is the span, qm is the unit load of the wire at maximum tension, tm is the maximum tension, tm is the temperature of the wire at maximum tension, qc is the unit load of the wire at inflection point temperature,
based on the tension T of the carbon fiber composite core wire at the maximum sag point at the inflection point temperature C Generating the knee temperature t c Wherein, in the process,
Figure BDA0003133968560000044
wherein E represents the elastic modulus of the carbon fiber composite core wire, tc is the tension of the carbon fiber composite core wire at the maximum sag point at the inflection point temperature, A is the cross-sectional area of the carbon fiber composite core wire, alpha and alpha a represent the thermal expansion coefficients of the carbon fiber composite core wire and the aluminum alloy wire respectively, t 0 Which represents the initial temperature of the molten steel,
in the inflection point temperature measurement method of the carbon fiber composite core wire, when the span of the carbon fiber composite core wire is a flat span, the height difference angle beta is 0.
When the inflection point temperature is lower than the inflection point temperature, the elongation of the composite core wire is equal to the elongation of the carbon fiber core and the elongation of the aluminum alloy wire, and the following equation Δ L = Δ L a ＝ΔL i Wherein Δ L is the elongation of the composite core wire; Δ La is the elongation of the aluminum alloy wire; Δ Li is the elongation of the carbon fiber core.
The elongation of the wire is composed of both thermal expansion due to temperature rise and elongation due to tension applied to the wire, regardless of weather conditions.
Figure BDA0003133968560000051
Wherein σ, σ a, σ i represent the stress of the lead wire, the stress of the aluminum alloy wire, and the stress of the carbon fiber core, respectively.
E, ea, ei represent the modulus of elasticity of the wire, the modulus of elasticity of the aluminum alloy wire, and the modulus of elasticity of the carbon fiber core, respectively.
Alpha, alpha a and alpha i respectively represent the thermal expansion coefficients of the lead wire, the aluminum alloy wire and the carbon fiber core.
t represents the current temperature. t0 represents the initial temperature.
From the above simultaneous equations (1) and (2) are simplified
σ a ＝[+(α-α a )(t-t 0 )]·Ea (4)
From the above simultaneous equations, the reduction of (1) and (3) can be obtained
σ i ＝[+(α-α i )(t-t 0 )]·E i (5)
The above formulas (4) and (5) represent the stress of the aluminum alloy wire and the carbon fiber composite core respectively
When the temperature reaches the inflection point temperature, σ a =0 can be obtained since the aluminum alloy wire is no longer stressed
Simplifying to obtain:
Figure BDA0003133968560000061
tc is the tension of the wire at the maximum point of sag at the inflection temperature; a is the cross-sectional area
(6) The relationship between the inflection point temperature and the tension at the maximum sag point is shown.
Under the inclined span, the electric wire is approximately regarded as an inclined parabola, the C point at the middle point is the maximum sag point, the T0 point is the tension borne by the C point, and the formula is based on the length of the inclined span wire
Figure BDA0003133968560000062
q is the lead unit load beta is the height difference angle,
the wire length Lm at maximum tension = the initial length of the wire + the total elongation of elasticity and thermal expansion Δ Lm; linear length Lc at knee temperature = initial length of wire + total elongation of elasticity and thermal expansion Δ Lc
L m -L c ＝ΔL m -ΔL c (8)
The above expression (8) is developed according to the calculation method of the line length and the elongation
Figure BDA0003133968560000063
In engineering, because the arc sag of the wire is small, the ratio of the arc sag to the span is generally only within a few percent, the length of the wire in the span is only increased by about a thousandth of the distance between suspension points, and alpha is considered to be the same when the wire is under the maximum tension and the inflection point temperature, thereby simplifying the process (9)
Figure BDA0003133968560000064
(10) Also shows the relationship between Tc and Tc, into which (6) is introduced
Figure BDA0003133968560000065
(11) Is a one-dimensional cubic equation for Tc to further reduce (11)
Figure BDA0003133968560000071
Namely that
T C 3 +KT C 2 +N＝0 (13)
Wherein
Figure BDA0003133968560000072
Figure BDA0003133968560000073
If the gear is in the flat gear, the beta angle is 0 degree.
The unknown number Tc in the formula can be obtained by programming by Newton's approximation iteration method, and the temperature Tc and the tension Tc at the inflection point can be obtained.
The method can be used for calculating the inflection point temperature by using both an inclined gear and a flat gear.
In one embodiment, tension T C Conversion relationship with inflection point temperature:
Figure BDA0003133968560000074
Figure BDA0003133968560000075
Figure BDA0003133968560000076
wherein K =
Figure BDA0003133968560000081
Figure BDA0003133968560000082
The conversion relation between the tension and the inflection point temperature is that Tc can be obtained by solving a one-element-three-order equation because other values are known constants in the practical calculation process. After Tc is obtained, the mixture is passed
Figure BDA0003133968560000083
Finally, the inflection point temperature t is obtained 0 。
The invention is in T C 3 +KT C 2 The + N =0 formula introduces a height difference angle beta, the height difference between two suspension points of the same span is called the height difference for short, and the included angle between the connecting line of the two suspension points and the horizontal plane, after the height difference angle beta is introduced, the calculation formula is not limited to the flat span or the inclined span, and the inflection point temperature can be obtained according to the actual situation only by measuring the actual height difference angle of the construction site and substituting the height difference angle into the formula.
Finally, it should be noted that: the embodiments described are only a few embodiments of the present application, not all embodiments, and all other embodiments that can be obtained by one skilled in the art without making any inventive effort based on the embodiments in the present application are intended to be covered by the present application.
While certain exemplary embodiments of the present invention have been described above by way of illustration only, it will be apparent to those of ordinary skill in the art that the described embodiments may be modified in various different ways without departing from the spirit and scope of the present invention. Accordingly, the drawings and description are illustrative in nature and should not be construed as limiting the scope of the invention.

Claims (2)

1. A method for measuring the inflection point temperature of a carbon fiber composite core wire is characterized by comprising the following steps of:
measuring span L, height difference angle beta and initial temperature t of carbon fiber composite core wire 0 Wherein the carbon fiber composite core lead comprises a carbon fiber core and an aluminum alloy wire, the height difference angle beta is an included angle between the height difference between two suspension points with the same span L and the horizontal plane,
based on the span L, the altitude difference angle beta and the initial temperature t 0 Calculating the tension T of the carbon fiber composite core wire at the maximum sag point at the inflection point temperature C Wherein, T C 3 +KT C 2 +N＝0，
Figure FDA0003809702710000011
Figure FDA0003809702710000012
Wherein E represents the elastic modulus of the carbon fiber composite core wire, alpha and alpha a represent the thermal expansion coefficients of the carbon fiber composite core wire and the aluminum alloy wire respectively, and t 0 Represents the initial temperature, tc is the tension of the carbon fiber composite core wire at the maximum sag point at the inflection point temperature; a is the cross-sectional area of the carbon fiber composite core wire, beta is a height difference angle, L is a span, qm is the unit load of the wire at the maximum tension, tm is the maximum tension, tm is the temperature of the wire at the maximum tension, qc is the unit load of the wire at the inflection point temperature,
based on the tension T of the carbon fiber composite core wire at the maximum sag point at the inflection point temperature C Generating the knee temperature t c Wherein, in the step (A),
Figure FDA0003809702710000013
wherein E represents the elastic modulus of the carbon fiber composite core wire, tc is the tension of the carbon fiber composite core wire at the maximum sag point at the inflection point temperature, A is the cross-sectional area of the carbon fiber composite core wire, alpha and alpha a represent the thermal expansion coefficients of the carbon fiber composite core wire and the aluminum alloy wire respectively, t 0 Representing the initial temperature, tension T C Conversion relationship with inflection point temperature:
Figure FDA0003809702710000014
Figure FDA0003809702710000015
Figure FDA0003809702710000016
wherein
Figure FDA0003809702710000017
Figure FDA0003809702710000021
2. The inflection point temperature measuring method of a carbon fiber composite core wire as claimed in claim 1, wherein the high difference angle β is 0 when the span of the carbon fiber composite core wire is a flat span.
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WO2015066889A1 (en) * 2013-11-08 2015-05-14 佛冈鑫源恒业电缆科技有限公司 Joint structure of carbon fiber composite core wire
CN105870863B (en) * 2016-05-19 2017-11-07 凤凰电力有限公司 Carbon fiber complex core strain clamp
CN208706292U (en) * 2018-06-14 2019-04-05 国网山东省电力公司电力科学研究院 A kind of stretch-proof carbon fiber composite core wire
CN110147522A (en) * 2019-05-22 2019-08-20 华北电力大学 A kind of strand type carbon fiber composite core wire inflection temperature, calculation method for stress
CN111504201B (en) * 2020-05-12 2021-11-26 国网天津市电力公司电力科学研究院 Method for measuring sag of flexible conductor in transformer substation
CN112556752B (en) * 2020-12-01 2022-07-12 国网浙江省电力有限公司经济技术研究院 In-service carbon fiber composite core wire mechanical property testing method, device and system

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