CN113936874B - GIL insulator surface charge inhibition method based on ground electrode partial coating - Google Patents

GIL insulator surface charge inhibition method based on ground electrode partial coating Download PDF

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Publication number
CN113936874B
CN113936874B CN202111201537.0A CN202111201537A CN113936874B CN 113936874 B CN113936874 B CN 113936874B CN 202111201537 A CN202111201537 A CN 202111201537A CN 113936874 B CN113936874 B CN 113936874B
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coating
ground electrode
insulator
conductivity
gil
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CN113936874A (en
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高宇
赵慧存
李敬
王欢
苑晓晨
韩涛
朱新山
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Tianjin University
State Grid Tianjin Electric Power Co Ltd
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Tianjin University
State Grid Tianjin Electric Power Co Ltd
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    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01BCABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B19/00Apparatus or processes specially adapted for manufacturing insulators or insulating bodies
    • H01B19/04Treating the surfaces, e.g. applying coatings
    • GPHYSICS
    • G06COMPUTING; CALCULATING OR COUNTING
    • G06FELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00Computer-aided design [CAD]
    • G06F30/20Design optimisation, verification or simulation

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  • Theoretical Computer Science (AREA)
  • Computer Hardware Design (AREA)
  • Evolutionary Computation (AREA)
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  • General Engineering & Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Insulators (AREA)

Abstract

The invention relates to a GIL insulator surface charge inhibition method based on local coating of a ground electrode, wherein a low-conductivity coating is coated in the ground electrode to help inhibit a distorted electric field, so that charge accumulation in a non-planar area is inhibited, and meanwhile, the method is simple in process, suitable for large-area coating, low in price of a coating composite material and beneficial to mass production.

Description

GIL insulator surface charge inhibition method based on ground electrode partial coating
Technical Field
The invention belongs to the technical field of high voltage and insulation, and relates to a GIL insulator surface charge inhibition method based on local coating of a ground electrode, which is used for regulating electric field distribution and preventing stronger gas ionization when metal particles touch the ground electrode.
Background
Because the areas of China are large, climates and geographical environments are complex, large-capacity long-distance power transmission lines are mostly in areas with severe climatic environments, the traditional overhead line power transmission mode is easily affected by dirt and rain and snow weather, and the gas-insulated closed power transmission line (Gas Insulated transmission Line, GIL) is used as a novel power transmission line, and has the advantages of large transmission capacity, small occupied area, flexible arrangement, high reliability, long service life, small influence of the environment and the like, so that the GIL is widely put into use under various voltage levels worldwide. In addition, the gas-insulated metal-enclosed switchgear (Gas Insulated Switchgear, GIS) has excellent performance, can meet the higher requirements on converter and substation equipment along with the urban process, is widely used in alternating current transmission systems, and can be expected to have huge application potential in continuously advancing ultra-high voltage direct current engineering, namely direct current GIL and GIS.
However, the current research on the direct current GIL and the GIS is relatively scarce, and a large number of engineering problems are included in the research and development of people. The insulator is an important component in GIL and GIS, and plays roles of basic mechanical fixing, electrical insulation, air chamber isolation and the like. According to previous experience, the insulation characteristics of the gas-solid interface of the basin-type insulator greatly influence the reliability of the gas-insulated equipment. Under the direct current electric field, free charges are accumulated on the surface of the basin-type insulator through contact and non-contact ways, and the accumulated charges on the surface distort the surface electric field on one hand; on the other hand, seed charge is also provided for the creeping discharge, thereby promoting creeping flashover.
At present, surface charge is widely considered as one of the important reasons for reducing the gas-solid interface insulating performance of the basin-type insulator. In addition, during the production, transportation, installation and switching action of the equipment, some metal scraps are inevitably introduced into the gas insulation equipment, and metal particles moving to the vicinity of the insulator directly distort the surface electric field of the insulator on one hand, and on the other hand, accumulation of charges on the surface of the insulator is caused, so that the insulation performance of the insulator is seriously damaged. It is counted that approximately four of the insulation failures of GIL/GIS devices are caused by metal particle contaminants.
Therefore, in order to ensure the insulation safety of the gas insulation sealing equipment and ensure the smooth development of the extra-high voltage direct current transmission engineering, a method for regulating and controlling the surface charge is necessary to be searched for, and the insulation performance of the insulator is improved.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a GIL insulator surface charge inhibition method based on local coating of a ground electrode.
The invention solves the technical problems by the following technical proposal:
a GIL insulator surface charge suppression method based on local coating of a ground electrode is characterized in that: the method comprises the following steps:
s1, establishing a corresponding simulation model according to the shape of an insulator, and selecting proper coating conductivity S, coating height h and coating thickness d through simulation;
s2, the conductivity S calculated in the simulation of the step S1 is 2 multiplied by 10 -16 S/m~2×10 -14 S/m, combining the conductivity value, and adjusting the content of nano alumina in the coating to obtain the coating with the conductivity meeting the condition;
and S3, preparing the coating according to the coating determined in the steps S1 and S2, and uniformly brushing the coating on the inner side of the ground electrode according to the proper coating thickness d and height h.
The coating thickness d is in the range of 0.1mm to 0.7mm.
Furthermore, the coating height h is flush with the highest point of the insulator.
The invention has the advantages that;
1. according to the method for inhibiting the surface charge accumulation of the insulator in the GIL based on the local coating of the ground electrode, the coating with low conductivity is coated in the grounded shell of the GIL, when the conductivity is low, a strong electric field can be shared in the coating part, and the electric field intensity of the gas part is reduced, so that the charge accumulation is reduced.
2. According to the method for inhibiting the surface charge accumulation of the insulator in the GIL based on the local coating of the ground electrode, aiming at the disc-shaped epoxy insulator with the real size and the complex surface morphology, a ground electrode coating scheme suitable for the insulator with the real size is provided, when metal particles are stained near the ground electrode under direct current voltage, the local electric field is distorted, and therefore a large amount of charges can be accumulated on the surface of the insulator. Because the electric field strength is inversely proportional to the conductivity of the material under the direct-current electric field, after a layer of low-conductivity coating is coated inside the ground electrode, the local electric field of gas side distortion can be restrained, and metal particles are prevented from directly contacting the ground electrode, so that the effect of restraining charge accumulation is achieved; the insulator surface charge density of the technology is lower than that of an uncoated insulator, and the electric field distortion of the insulator surface when metal particles exist is reduced, so that the risk of flashover accidents is reduced. In addition, the technology is simple in process, suitable for large-area coating, low in price of the coating composite material and beneficial to large-scale production.
3. According to the method for inhibiting the surface charge accumulation of the insulator in the GIL based on the local coating of the ground electrode, when metal particles exist, the electric field at the metal particles is distorted, gas ionization is generated, and therefore a large amount of charges are easily accumulated in the non-planar area of the insulator, and the low-conductivity coating is coated inside the ground electrode to help inhibit the distorted electric field, so that the charge accumulation in the non-planar area is inhibited.
Drawings
FIG. 1 is a schematic view of an insulator in GIL of the present invention;
FIG. 2 is an electrical field profile of an uncoated insulator surface;
FIG. 3 is a graph showing the electric field distribution on the surface of an insulator after electrode coating according to the present invention;
fig. 4 is a process flow diagram of the present invention for applying a coating.
Detailed Description
The invention is further illustrated by the following examples, which are intended to be illustrative only and not limiting in any way.
1. Coating scheme
(1) In fig. 1, the insulator structure in GIL is shown, in which the metal particles have various shapes such as a line shape, a sphere shape, a sheet shape, a spiral shape, etc., and the line shape and the sphere shape are most typical. Because the end electric field of the linear metal particles is very high, micro discharge is easy to occur, and a large amount of generated charges can provide seed charges for flashover, and finally the breakdown voltage is reduced, the linear metal particles have the greatest influence on the insulation performance of equipment. Wherein the length of the linear particles is mostly in the millimeter order, and the diameter is in the hundred micrometers order. Therefore, in order to simulate the most serious situation in reality, a linear metal particle having a length of 5mm and a radius of 0.5mm in cross section is applied to the ground electrode.
(2) To simulate the charge accumulation on the insulator surface in the presence of metal particles in the ground electrode in the GIL under real conditions. As shown in FIG. 2, the simulation results of the electric field distribution of the surface of an uncoated insulator show that when metal particles exist near the ground electrode, the electric field strength is 5.4kV/mm, and gas ionization is easy to occur.
(3) According to the invention, a layer of low-conductivity coating is uniformly coated inside the grounding electrode, and when the coating is too thin, the effect of sharing the field intensity is not obvious; when the coating is too thick, the effect of inhibiting charge accumulation is limited, and meanwhile, the too thick coating also can lead to the problems of heat dissipation, uniformity of the coating and the like.
Wherein the coating thickness d is 0.5mm, h is 50mm, and the conductivity S is 2×10 -15 S/m. FIG. 3 is a simulation result of the electric field distribution on the surface of the coated insulator, wherein the electric field is 2.2kV/mm, and the electric field strength is reduced by 59.2% compared with that of the uncoated insulator.
2. The preparation flow chart of the coating is as follows:
the coating coated on the ground electrode is epoxy resin doped with nano alumina and nano Al 2 O 3 The conductivity of the epoxy resin can be reduced after the particles, and the preparation process is shown in fig. 4:
firstly, weighing nano alumina particles with certain mass, placing the nano alumina particles in a welding rod drying box, setting the temperature of the drying box to be 100 ℃, and setting the time to be 1h to remove water as much as possible; weighing a certain amount of epoxy resin, adding the dried nano alumina particles into the epoxy resin according to a set mass ratio, and fully stirring to obtain a primary mixed solution; placing the obtained primary mixed solution into a digital display constant temperature magnetic stirring water bath kettle, and magnetically stirring for 1h at 50 ℃; transferring the stirred mixed solution into an ultrasonic cleaner, setting the ultrasonic temperature to be 50 ℃, and performing dispersion treatment for 1h by utilizing ultrasonic waves to ensure that nano particles are uniformly dispersed in the epoxy resin; weighing a curing agent according to the mass ratio of the epoxy resin to the curing agent of 100:30, and adding the curing agent into the mixed solution of the nano alumina particles and the epoxy resin; wiping and cleaning the ground electrode with alcohol, and uniformly coating the coating on the ground electrode according to parameters; in order to remove bubbles in the material, setting the temperature of a vacuum drying oven to 30 ℃, and carrying out degassing treatment for 1h in a vacuum environment; after the above treatment, the ground electrode was put into a thermal elongation tester to be cured, at 70℃for 3 hours, and at 120℃for 3 hours to be post-cured.
The invention is based on a method for inhibiting charge accumulation of insulators in GIL by coating a ground electrode, taking a disc insulator with a complicated surface and a size of 126kV as an example, and the size is shown in fig. 1. The coating on the inner side of the ground electrode is an epoxy composite material doped with 5%wt nano alumina, so that the conductivity S of the coating is 2 multiplied by 10 -15 S/m, 2X 10 lower than air -14 S/m. The thickness d of the coating is 0.5mm, h is flush with the highest point of the insulator and is 50mm.
The epoxy/alumina coating used in the present technology can reduce the risk of insulator flashover by coating the inside of the ground electrode with a coating that inhibits surface charge accumulation in the presence of metal particles. The coating prepared by the technology can be applied to insulation of formed equipment in a large area, can obviously improve the surface insulation performance of the equipment, and has higher economic value and practical effect.
Although the embodiments of the present invention and the accompanying drawings have been disclosed for illustrative purposes, those skilled in the art will appreciate that: various substitutions, changes and modifications are possible without departing from the spirit and scope of the invention and the appended claims, and therefore the scope of the invention is not limited to the embodiments and the disclosure of the drawings.

Claims (1)

1. A GIL insulator surface charge suppression method based on local coating of a ground electrode is characterized in that: the method comprises the following steps:
s1, establishing a corresponding simulation model according to the shape of an insulator, and selecting proper coating conductivity S, coating height h and coating thickness d through simulation;
s2, the conductivity S calculated in the step S1 in a simulation way is within a range of 2×10 -16 S/m~2×10 -14 S/m, combining the conductivity value, and adjusting the content of nano alumina in the coating to obtain the coating with the conductivity meeting the condition;
s3, preparing the coating according to the coating determined in the S1 and the S2, and uniformly brushing the coating on the inner side of the ground electrode according to the proper coating thickness d and the proper coating height h;
the numerical range of the coating thickness d is 0.1 mm-0.7 mm;
the coating height h is flush with the highest point of the insulator.
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CN114656859A (en) * 2022-03-25 2022-06-24 国网江苏省电力有限公司电力科学研究院 Method for inhibiting GIS free metal particles based on semi-conductive coating layer

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB983402A (en) * 1960-07-22 1965-02-17 Tamotsu Watanabe Method of coating articles by static electricity
US3397083A (en) * 1965-04-14 1968-08-13 Champion Spark Plug Co Insulator body having an electrically conductive surface and method
US6342679B1 (en) * 1996-07-31 2002-01-29 Pirelli Cavi S.P.A. Two-layered elastic tubular covering for electric components
CN108717888A (en) * 2018-05-29 2018-10-30 南方电网科学研究院有限责任公司 Insulator with high dielectric constant film and preparation method thereof
CN113345659A (en) * 2021-03-25 2021-09-03 天津大学 Basin-type insulator surface charge prevention and control method based on flexible coating

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB983402A (en) * 1960-07-22 1965-02-17 Tamotsu Watanabe Method of coating articles by static electricity
US3397083A (en) * 1965-04-14 1968-08-13 Champion Spark Plug Co Insulator body having an electrically conductive surface and method
US6342679B1 (en) * 1996-07-31 2002-01-29 Pirelli Cavi S.P.A. Two-layered elastic tubular covering for electric components
CN108717888A (en) * 2018-05-29 2018-10-30 南方电网科学研究院有限责任公司 Insulator with high dielectric constant film and preparation method thereof
CN113345659A (en) * 2021-03-25 2021-09-03 天津大学 Basin-type insulator surface charge prevention and control method based on flexible coating

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Title
Surface discharge behaviour of coated electrodes in gas-insulated systems under DC voltage stress;Thomas G¨otz;《2018 IEEE Conference on Electrical Insulation and Dielectric Phenomena》;477-480 *

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