CN112651159A - High-voltage cross-connection cable joint transient electric stress assessment method - Google Patents
High-voltage cross-connection cable joint transient electric stress assessment method Download PDFInfo
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- 239000011241 protective layer Substances 0.000 claims description 18
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Abstract
The invention provides a method for evaluating transient electric stress of a high-voltage cross-connection cable joint. The technical scheme of the invention combines the special structure of the high-voltage cross interconnection cable connector, considers the relative transient overvoltage between two ends of the sheath, establishes an electric field distribution calculation model in finite element simulation software based on the high-voltage cross interconnection cable connector structure, and introduces cable connector operation overvoltage waveform data and cable connector sheath voltage transient overvoltage waveform data to calculate the electric field intensity distribution of each part in the connector, thereby evaluating the transient electric stress of the high-voltage cross interconnection cable connector and having better reliability on the result.
Description
Technical Field
The invention relates to the field of electric power, in particular to a method for evaluating transient electric stress of a high-voltage cross-connection cable joint.
Background
High voltage cable lines have been of great interest as one of the main ways to supply power in cities for safety and stability of operation. Because the insulation of the cable line is solid insulation, the cable line belongs to unrecoverable insulation, and the electric tree with the weak insulation point is easy to develop and even break down under high transient overvoltage, single-phase grounding or multi-phase grounding faults are caused, even accidents such as fire explosion are caused, and great threat is brought to the safe and reliable operation of the power grid. According to the statistical analysis of the faults of the high-voltage cable lines in recent years, under the condition of not considering external force damage, the faults of the cross interconnection cable joints account for more than 50% of the faults of the cable lines, so that the transient electric stress evaluation of the cross interconnection cable joints needs to be performed in an important point during the design of the cross interconnection cable joints.
At present, on the premise that the electrical stress of the cross interconnection cable connector is defective and gradually developed, power frequency and direct current are mainly used, a small number of researches on transient electrical stress are also established on the basis of standard operation impulse voltage waveforms, and the conclusion that the electrical stress of the cable connector at the tail end of a line is high and is easy to break down and the fault needs to be developed for a certain time is generally concluded. The technical schemes do not consider factors such as the actual operation overvoltage waveform born by the high-voltage cross interconnection cable joint, the transient voltage existing between the protective layers at two ends of the cross interconnection cable joint and the like, so that the breakdown fault of the cross interconnection cable joint at the head end of the line after the closing operation of a plurality of cables in recent years cannot be explained, and the reliability of the evaluation result is not high.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a method for evaluating the transient electrical stress of a high-voltage cross-connection cable joint. In order to achieve the purpose of the invention, the technical scheme of the invention is as follows.
A method for evaluating transient electrical stress of a high-voltage cross-connection cable joint comprises the following steps:
establishing an electric field distribution calculation model of three equipotential surfaces, namely a grounding equipotential surface, a core equipotential surface and a protective layer equipotential surface of the cable joint;
transient overvoltage waveform data of a wire core of a cable joint relative to a protective layer and relative transient overvoltage waveform data between two ends of the protective layer are obtained based on an electromagnetic transient simulation result of line operation overvoltage;
and (3) importing the transient overvoltage waveform data into corresponding positions in the established electric field distribution calculation model, calculating electric field intensity waveform data of electric field distribution of each position in the cable joint along with time change in the electric field distribution calculation model, acquiring the maximum electric field intensity of the cable joint, comparing the maximum electric field intensity with the breakdown field intensity of the main insulation of the cable joint, and evaluating the transient electric stress of the high-voltage cross interconnection cable joint.
Preferably, the step of introducing the transient overvoltage waveform data into the corresponding position in the established electric field distribution calculation model includes introducing the transient overvoltage waveform data of the cable joint core relative to the sheath into the equipotential surface of the core in the established electric field distribution calculation model, and introducing the transient overvoltage waveform data between two ends of the sheath of the cable joint into the equipotential surface of the sheath in the established electric field distribution calculation model.
Preferably, the evaluating the transient electrical stress of the high-voltage cross-connect cable joint comprises calculating the electrical stress based on the maximum electric field strength of the cable joint and the main insulation breakdown field strength of the cable joint.
Compared with the prior art, the invention has the beneficial technical effects that: the technical scheme of the invention combines the special structure of the high-voltage cross interconnection cable connector, considers the relative transient overvoltage between two ends of the sheath, establishes an electric field distribution calculation model in finite element simulation software based on the high-voltage cross interconnection cable connector structure, introduces cable connector operation overvoltage waveform data obtained by electromagnetic transient simulation of a cable line, fully considers the voltage of the sheath of the cable connector, and calculates the electric field intensity distribution of each part in the connector, thereby evaluating the transient electric stress of the high-voltage cross interconnection cable connector and having better reliability on the result.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained from the drawings without inventive effort.
FIG. 1 is a cross-sectional view of a high voltage cross-connect cable joint;
FIG. 2a is a diagram showing an equipotential layer of core voltage of a model for electric field distribution calculation; FIG. 2b is a schematic diagram of a sheath voltage equipotential layer of the electric field distribution calculation model; FIG. 2c is a schematic diagram of a ground plane voltage equipotential layer of the electric field distribution calculation model;
FIG. 3 is a transient overvoltage waveform of a cable connector core relative to a sheath;
FIG. 4 is a relative transient overvoltage waveform between two ends of a sheath of a cable splice;
FIG. 5 is a waveform of the electric field strength at a location of a cable joint as a function of time;
description of reference numerals:
firstly, shielding a cable insulating layer; ② a cable insulating layer; thirdly, a metal crimping pipe; fourthly, the cable core is obtained; fifthly, the low-voltage semi-conductive stress cone; sixthly, the metal protective layer is formed; is a copper shell; the eighty percent is a silicon rubber insulating layer; ninthly, a high-voltage semi-conductive stress cone; and R is the semi-conductive coating of the cable joint.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all the embodiments.
As shown in fig. 1, the core and the two end sheaths of the cable joint of the high-voltage cross-connection cable joint are three metal parts insulated from each other. Therefore, a corresponding electric field distribution calculation model is established in finite element simulation software, the model should have three equipotential surfaces including a joint core and joint protective layers at two ends, the equipotential surface of the protective layer at one side can be set as a grounding equipotential surface in actual calculation, and the other two equipotential surfaces are named as a core equipotential surface and a protective layer equipotential surface respectively.
According to the cross-section structure diagram of the high-voltage cross-connection cable joint shown in fig. 1, a simplified structure diagram which omits a middle conductor part shown in fig. 2 is established in AutoCAD software, and is introduced into finite element simulation software, and corresponding parameters of materials of each part are set, so that an electric field distribution calculation model with three equipotential surfaces shown in fig. 3 is obtained.
A system simulation model is established according to engineering practice in electromagnetic transient simulation calculation software, transient overvoltage waveforms of cable joint wire cores and protective layers on two sides of a high-voltage cable circuit are calculated under the severe switching-on working condition, the potential of the protective layer on one side is fixed to be 0, and transient overvoltage waveforms of the wire cores relative to the protective layer and relative transient overvoltage waveforms between two ends of the protective layer are obtained.
The method for evaluating the transient electrical stress of the high-voltage cross-connection cable joint in the embodiment specifically comprises the following steps:
establishing an electric field distribution calculation model of three equipotential surfaces, namely a grounding equipotential surface, a core equipotential surface and a protective layer equipotential surface of the cable joint;
transient overvoltage waveform data of a wire core of a cable joint relative to a protective layer and relative transient overvoltage waveform data between two ends of the protective layer are obtained based on an electromagnetic transient simulation result of line operation overvoltage;
and importing the transient overvoltage waveform data into corresponding positions in the established electric field distribution calculation model, calculating electric field intensity waveform data of electric field distribution of each position in the cable joint along with time change in the electric field distribution calculation model, acquiring the maximum electric field intensity of the cable joint, calculating electric stress based on the maximum electric field intensity of the cable joint and the main insulation breakdown field intensity of the cable joint, and evaluating the transient electric stress of the high-voltage cross-connected cable joint.
Illustratively, a 220kV high-voltage cable transmission line is taken as a research object, a simulation system is established in electromagnetic transient simulation software, and a transient overvoltage waveform of a core relative to a sheath and a relative transient overvoltage waveform between two ends of the sheath under the most severe switching condition of each cable joint are obtained by calculating the switching-on overvoltage amplitude of each cable joint under different working conditions, wherein the transient overvoltage waveform of the core relative to the sheath of a certain cable joint is shown in fig. 3, and the relative transient overvoltage waveform between two ends of the sheath is shown in fig. 4.
And (3) importing the transient overvoltage waveform data into corresponding positions in the established electric field distribution calculation model, calculating the waveform of the electric field distribution of each position of the cable joint along with the change of time in the electric field distribution calculation model, acquiring the maximum electric field intensity of each position in the cable joint, comparing the maximum electric field intensity with the breakdown field intensity of the main insulation of the cable joint, and evaluating the electric stress of the cable joint.
And introducing the voltage waveform data shown in fig. 3 into a core equipotential surface in the established electric field distribution calculation model, introducing the voltage waveform data shown in fig. 4 into a sheath equipotential surface in the established electric field distribution calculation model, and calculating to obtain data of the variation of the electric field intensity at each position in the cable joint along with time, wherein the variation of the electric field intensity at a certain position along with time is shown in fig. 5. The maximum electric field intensity can reach 24.04kV/mm, the breakdown field intensity of the main insulating silicon rubber of the cable joint is 25kV/mm, the electric stress reaches 0.96, and the structure is optimized or the main insulating material with better insulating property is used to improve the margin during design.
The above-mentioned embodiments are only specific embodiments of the present application, and are used for illustrating the technical solutions of the present application, but not limiting the same, and the scope of the present application is not limited thereto, and although the present application is described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: any person skilled in the art can modify or easily conceive the technical solutions described in the foregoing embodiments or equivalent substitutes for some technical features within the technical scope disclosed in the present application; such modifications, changes or substitutions do not depart from the spirit and scope of the present disclosure, which should be construed in light of the above teachings. Are intended to be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.
Claims (3)
1. A method for evaluating transient electrical stress of a high-voltage cross-connection cable joint is characterized by comprising the following steps:
establishing an electric field distribution calculation model of three equipotential surfaces, namely a grounding equipotential surface, a core equipotential surface and a protective layer equipotential surface of the cable joint;
transient overvoltage waveform data of a wire core of a cable joint relative to a protective layer and relative transient overvoltage waveform data between two ends of the protective layer are obtained based on an electromagnetic transient simulation result of line operation overvoltage;
and (3) importing the transient overvoltage waveform data into corresponding positions in the established electric field distribution calculation model, calculating electric field intensity waveform data of electric field distribution of each position in the cable joint along with time change in the electric field distribution calculation model, acquiring the maximum electric field intensity of the cable joint, comparing the maximum electric field intensity with the breakdown field intensity of the main insulation of the cable joint, and evaluating the transient electric stress of the high-voltage cross interconnection cable joint.
2. The method of claim 1, wherein the step of introducing transient overvoltage waveform data into corresponding locations in the established electric field distribution calculation model comprises introducing transient overvoltage waveform data of cable splice cores relative to the sheath into a core equipotential surface in the established electric field distribution calculation model, and introducing transient overvoltage waveform data between two ends of the cable splice sheath into a sheath equipotential surface in the established electric field distribution calculation model.
3. The method of claim 2, wherein the evaluating the transient electrical stress of the high voltage cross-connect cable joint comprises calculating the electrical stress based on a maximum electrical field strength of the cable joint and a main insulation breakdown field strength of the cable joint.
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| CN202011564084.3A CN112651159A (en) | 2020-12-25 | 2020-12-25 | High-voltage cross-connection cable joint transient electric stress assessment method |
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| CN202011564084.3A CN112651159A (en) | 2020-12-25 | 2020-12-25 | High-voltage cross-connection cable joint transient electric stress assessment method |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105844029A (en) * | 2016-03-29 | 2016-08-10 | 顺德职业技术学院 | Research method for high voltage cable terminal joint |
| CN109324236A (en) * | 2018-09-29 | 2019-02-12 | 国网山西省电力公司太原供电公司 | A kind of assessment of fault method based on cable connector typical defect |
| CN109635360A (en) * | 2018-11-21 | 2019-04-16 | 宁波恒晨电力建设有限公司 | Lightning Strike Risk Evaluation method and device based on cascade emulation |
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2020
- 2020-12-25 CN CN202011564084.3A patent/CN112651159A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105844029A (en) * | 2016-03-29 | 2016-08-10 | 顺德职业技术学院 | Research method for high voltage cable terminal joint |
| CN109324236A (en) * | 2018-09-29 | 2019-02-12 | 国网山西省电力公司太原供电公司 | A kind of assessment of fault method based on cable connector typical defect |
| CN109635360A (en) * | 2018-11-21 | 2019-04-16 | 宁波恒晨电力建设有限公司 | Lightning Strike Risk Evaluation method and device based on cascade emulation |
Non-Patent Citations (4)
| Title |
|---|
| 伍国方: "高压直流电缆附件内缺陷对电场分布的影响研究", 《中国优秀博硕士学位论文全文数据库(硕士)工程科技Ⅱ辑》 * |
| 周秀君: "高压电缆终端多界面应力锥的优化设计", 《科技通报》 * |
| 宋淑伟等: "高压直流电缆接头稳态与暂态电场分布特征", 《高电压技术》 * |
| 赵鹏等: "直流叠加雷电冲击电压下±320kV直流电缆整体预制式接头典型故障机理分析", 《高电压技术》 * |
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Application publication date: 20210413 |