CN111270555A - Method for modifying transformer oil paper interface performance and nano modified transformer oil paper - Google Patents

Method for modifying transformer oil paper interface performance and nano modified transformer oil paper Download PDF

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CN111270555A
CN111270555A CN201911234210.6A CN201911234210A CN111270555A CN 111270555 A CN111270555 A CN 111270555A CN 201911234210 A CN201911234210 A CN 201911234210A CN 111270555 A CN111270555 A CN 111270555A
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oil
paper
transformer
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transformer oil
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周游
周文涛
陈维捷
彭能
隋三义
杨鑫
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Changsha University of Science and Technology
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    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
    • D21H17/63—Inorganic compounds
    • D21H17/67—Water-insoluble compounds, e.g. fillers, pigments
    • D21H17/675—Oxides, hydroxides or carbonates
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
    • D21H21/50—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties characterised by form
    • D21H21/52—Additives of definite length or shape
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
    • H01B3/18—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
    • H01B3/48—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances fibrous materials
    • H01B3/52—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances fibrous materials wood; paper; press board
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00—Details of transformers or inductances, in general
    • H01F27/28—Coils; Windings; Conductive connections
    • H01F27/32—Insulating of coils, windings, or parts thereof

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Wood Science & Technology (AREA)
  • Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Insulating Of Coils (AREA)

Abstract

The invention discloses a method for modifying the interface performance of transformer oil paper and nano modified transformer oil paper, wherein spherical TiO is dispersedly added into the interface between transformer oil and insulating oil paper in a transformer2Nanoparticles or Fe3O4The nano particles are 20-100 nm in diameter. Compared with the prior art, the invention inhibits the accumulation phenomenon of space charge at the oil-paper interface by adding the nano particles, and relieves the transformer oil and the oilThe dielectric constant difference between the paper dipping plates further changes the propagation characteristic of discharge at the interface and improves the flashover performance of the transformer oil-paper interface, thereby solving the technical problem of low insulating performance of the existing transformer oil-paper composite medium.

Description

Method for modifying transformer oil paper interface performance and nano modified transformer oil paper
Technical Field
The invention relates to the technical field of high-voltage insulation, in particular to a method for modifying transformer oil paper interface performance and nano modified transformer oil paper.
Background
The power transformer is used as a junction device of a power system, and the transformer fault caused by insulation fault accounts for more than 80 percent of transformer accidents of 110kV and above. The oil paper insulation is the main insulation structure of the oil-immersed power transformer, and the insulation performance of the oil paper insulation directly influences the operation stability of the power transformer. While the oil-paper interface is usually the weak point link for insulation, creeping discharge along coil cake spacers, screens, etc. is one of the most common faults in transformers. Due to the difference of the dielectric constant of the oiled paper medium, the influence of the surface structure and the moisture content distribution of the paperboard, discharge is easier to develop along the surface of the paperboard, irrecoverable damage is left on the surface of the paperboard, the effective insulation distance is reduced, and finally severe transformer faults caused by surface flashover are caused.
In order to reduce the creepage accident along the surface, people carry out a great deal of design optimization on the internal insulation structure of the transformer, and reduce the electric field tangent component of the paperboard surface to inhibit the discharge from spreading and developing along the paperboard surface. However, in some hanging-cover accident transformers, charring traces due to creeping discharge or flashover can still be found on the surface of the screen board. Therefore, in order to meet the requirements of extra-high voltage on high capacity, high voltage and miniaturization of the power transformer, further reduce the weight and the volume of the extra-high voltage power transformer, improve the safe and stable operation of a super-large-scale power transmission system, the improvement of the flashover performance of an oil-paper interface of the transformer and the development of a transformer oil-paper composite medium with higher insulating property are urgently needed.
Disclosure of Invention
The invention provides a method for modifying the interface performance of transformer oil paper and nano modified transformer oil paper, which are used for solving the technical problem that the insulating performance of the existing transformer oil paper composite medium is not high.
In order to solve the technical problems, the technical scheme provided by the invention is as follows:
a method for modifying the performance of an oil-paper interface of a transformer comprises the following steps:
spherical TiO is dispersedly added into the interface between transformer oil and insulating oil paper in the transformer2Nanoparticles or Fe3O4The nano particles have the diameter of 20-100 nm.
Preferably, the spherical TiO is dispersedly added into the interface between the transformer oil and the insulating oil paper in the transformer2Nanoparticles or Fe3O4Nanoparticles, including any of the following:
adding nano particles at an interface between the transformer oil and the insulating oil paper, and performing vacuum impregnation by using the transformer oil to modify the transformer oil paper interface;
dispersing the nano particles into the transformer oil to obtain the prepared nano modified transformer oil, dipping the insulating paper board in vacuum by using the nano modified transformer oil, and modifying the transformer oil-paper interface to obtain the nano modified transformer oil-paper.
Preferably, the nano particles are dispersed in the transformer oil, and the ratio of the nano particles in the nano modified transformer oil is 0.01 g/L-0.80 g/L.
Preferably, the prepared nano modified transformer oil has a moisture content of 5-8ppm, and the moisture content of the nano modified transformer oil paper is less than 0.5%.
A nanometer modified transformer oilpaper is provided, wherein spherical TiO is uniformly dispersed in the nanometer modified transformer oilpaper2Nanoparticles or Fe3O4The nano particles have the diameter of 20-100 nm.
Preferably, the nano modified transformer oil paper is prepared by the following method:
dispersing the nanoparticles into the transformer oil to obtain the prepared nano modified transformer oil;
and (3) carrying out vacuum impregnation on the insulating paperboard by using the nano modified transformer oil to obtain the nano modified transformer oil paper.
Preferably, the nano particles are dispersed in the transformer oil, and the ratio of the nano particles in the nano modified transformer oil is 0.01 g/L-0.80 g/L.
Preferably, the prepared nano modified transformer oil has a moisture content of 5-8ppm, and the moisture content of the nano modified transformer oil paper is less than 0.5%.
The invention has the following beneficial effects:
1. according to the method for modifying the performance of the oil-paper interface of the transformer, the accumulation phenomenon of space charges at the oil-paper interface is inhibited by dispersing the nano particles at the oil-paper interface, the dielectric constant difference between the transformer oil and the oil-immersed paper board is relieved, the propagation characteristic of discharge at the interface is changed, the flashover performance of the oil-paper interface of the transformer is improved, and the technical problem that the insulating performance of the existing oil-paper composite medium of the transformer is not high is solved.
2. According to the nano modified transformer oilpaper, the nano particles are uniformly dispersed in the transformer oilpaper, and can be dispersed to an oilpaper interface due to Brownian motion of the nano particles, so that the accumulation phenomenon of space charges at the oilpaper interface is inhibited by dispersing the nano particles at the oilpaper interface, the dielectric constant difference between the transformer oil and an oil-immersed paper board is relieved, the propagation characteristic of discharge at the interface is changed, the flashover performance of the oilpaper interface of the transformer is improved, and the technical problem that the insulating performance of the existing transformer oilpaper composite medium is not high is solved.
In addition to the objects, features and advantages described above, other objects, features and advantages of the present invention are also provided. The present invention will be described in further detail below with reference to the accompanying drawings.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:
FIG. 1 is a graph comparing the creeping discharge onset voltage and creeping flashover voltage curves of transformer oilpaper and nano-oilpaper in a preferred embodiment of the present invention;
FIG. 2 is the propagation characteristics of streamer discharges at the interface of transformer oilpaper and nano-oilpaper in the preferred embodiment of the present invention;
FIG. 3 is a graph showing the charge accumulation behavior at the interface between transformer oilpaper and nano-oilpaper in a preferred embodiment of the present invention;
FIG. 4 is a simulation calculation result of steady-state electric field distribution of oiled paper insulation for a needle-plate test electrode structure by finite element simulation under the premise of neglecting indentation of a paperboard surface in a preferred embodiment of the invention;
fig. 5 is a distribution diagram of electric field intensity of the surfaces of the pure oil-impregnated paperboard and the nano oil-impregnated paperboard in the preferred embodiment of the invention.
Detailed Description
The embodiments of the invention will be described in detail below with reference to the drawings, but the invention can be implemented in many different ways as defined and covered by the claims.
The first embodiment is as follows:
the implementation discloses a method for modifying the performance of an oil-paper interface of a transformer, which comprises the following steps:
spherical TiO is dispersedly added into the interface between transformer oil and insulating oil paper in the transformer2Nanoparticles or Fe3O4The nano particles have the diameter of 20-100 nm.
According to the method for modifying the performance of the oil-paper interface of the transformer, the accumulation phenomenon of space charges at the oil-paper interface is inhibited by dispersing the nano particles at the oil-paper interface, the dielectric constant difference between the transformer oil and the oil-immersed paper board is relieved, the propagation characteristic of discharge at the interface is changed, the flashover performance of the oil-paper interface of the transformer is improved, and the technical problem that the insulating performance of the existing oil-paper composite medium of the transformer is not high is solved.
In addition, in this embodiment, a nano modified transformer oilpaper in which spherical TiO is uniformly dispersed is also disclosed2Nanoparticles or Fe3O4The nano particles are 20-100 nm in diameter.
According to the nano modified transformer oilpaper, the nano particles are uniformly dispersed in the transformer oilpaper, and can be dispersed to an oilpaper interface due to Brownian motion of the nano particles, so that the accumulation phenomenon of space charges at the oilpaper interface is inhibited by dispersing the nano particles at the oilpaper interface, the dielectric constant difference between the transformer oil and an oil-immersed paper board is relieved, the propagation characteristic of discharge at the interface is changed, the flashover performance of the oilpaper interface of the transformer is improved, and the technical problem that the insulating performance of the existing transformer oilpaper composite medium is not high is solved.
Example two:
in order to verify the method for modifying the interface performance of the transformer oil paper and the superiority of the insulating performance of the nano modified transformer oil paper, a pure oil-immersed (pure transformer oil) paperboard is prepared to be used for carrying out an insulating performance comparison test with the nano modified transformer oil paper, and the specific contents are as follows:
preparing a pure oil impregnated paper board and a nano oil impregnated paper board (namely nano modified transformer oil impregnated paper):
the transformer oil used in the method is Clarity 25# transformer oil, and after filtration treatment, the content of particle impurities in the oil meets the standard formulated by CIGRE (International Large Power grid conference) working group, so that pure transformer oil (pure oil for short) is obtained. Using water bath ultrasonic treatment method to treat a certain quantity of semiconductor TiO2The nano particles are uniformly dispersed in pure oil to prepare nano modified transformer oil (nano oil for short). And standing the pure oil and the nano oil at 80 ℃ in a vacuum environment for 48 hours, and removing the influence of dissolved gas and water in the oil on a test result to obtain the dry pure oil and the dry nano oil.
The insulating paperboard used in the test was a prepressed paperboard made by widemann corporation and had a thickness of 2 mm. Firstly, cutting an insulating paperboard into 50mm multiplied by 85mm, placing the insulating paperboard in an air drying box, and drying the insulating paperboard for 48 hours in an environment at 105 ℃. And then respectively soaking the preliminarily dried paper boards into the dried pure oil and the dried nano oil, and carrying out vacuum impregnation for 48 hours at the temperature of 85 ℃ and under the vacuum environment of less than 100Pa to respectively obtain the pure oil-immersed paper boards and the nano oil-immersed paper boards (namely the nano modified transformer oilpaper). The moisture content of the paperboard and the oil sample are respectively measured by a Switzerland KF831 Karl Fischer moisture tester and a coulometric micro-water meter. After the drying treatment, the moisture content of the oil-immersed paperboard is less than 0.5%, and the moisture content of the transformer oil is 5-8 ppm.
And (II) testing the insulating property of the pure oil-immersed paperboard and the nano oil-immersed paperboard (namely the nano modified transformer oilpaper):
1. testing the creeping discharge initial voltage and the creeping flashover voltage:
the pure oil-immersed paper board and the nano oil-immersed paper board (namely, the nano modified transformer oilpaper) are respectively subjected to surface discharge initial voltage and surface flashover voltage tests to obtain test results shown in fig. 1, and as can be seen from fig. 1, the surface CDIV (discharge initial voltage) of the nano oil-immersed paper board is higher than that of the corresponding pure oil-immersed paper board at each electrode interval, and the amplitude can reach 12.1% -15.5%. This shows that the addition of the nanoparticles can inhibit and reduce the partial discharge activity of the oil-paper interface and increase the along-plane CDIV (discharge initiation voltage) of the oil-paper interface.
The surface flashover voltage test results of the pure oil-immersed paperboard and the nano oil-immersed paperboard are shown in fig. 2, and the surface flashover voltages of the pure oil-immersed paperboard and the nano oil-immersed paperboard are increased along with the increase of the electrode spacing. Under each interval, the surface flashover voltage of nanometer oily cardboard all is higher than the surface flashover voltage of pure oil immersion cardboard, and along with the increase of electrode spacing, promotes range and increases to some extent, for example under 20mm interval, compares in pure oil immersion cardboard, and the surface flashover voltage of nanometer oily cardboard has promoted 5kV, and then has nearly 9 kV's promotion when 40mm interval. The nano particles can not only improve the initial discharge voltage of the oil-paper insulation surface, but also obviously improve the flashover characteristic of the oil-paper interface, which has important significance for improving the insulation performance of the insulation surface in the transformer.
2. Testing of charge accumulation characteristics at the interface:
the pure oil-immersed paper board and the nano oil-immersed paper board (i.e. the nano modified transformer oilpaper) are respectively subjected to a charge accumulation characteristic test at the interface, so as to obtain a test result shown in fig. 3, and it can be known from fig. 3 that the charge density accumulated on the surface of the nano oil-immersed paper board is far lower than that of the pure oil-immersed paper board under the action of the direct-current polarization voltage.
The above studies indicate that TiO2The nano particles can obviously improve the impact surface flashover characteristic of the transformer oil-immersed paperboard and improve the surface flashover voltage of the transformer oil-immersed paperboard. Of note is TiO2The nano particles can improve the positive polarity surface flashover voltage of the oil immersed paperboard, and can also improve the surface flashover voltage of the oil immersed paperboard of the transformer under the action of negative polarity lightning impulse voltage, and the improvement effect of the nano particles on transformer oil is different from that of the nano particles. This is because during the flashover of the oil-impregnated paper board along the surface, the discharge flow not only occurs in the oil gap, but also progresses along the oil-paper interface area near the surface of the paper board. In addition to the excellent positive polarity breakdown performance of the nano oil, the electric field distribution among the oil paper media under the action of an electric field and the charge characteristics of the oil paper interface directly influence the interface insulation performance of the oil-immersed paper board of the transformer. The section respectively analyzes the influence of the nano particles on the interface insulating property of the oil-immersed paperboard of the transformer from the angle of the influence of electric field distribution and interface charge on the development of the flow.
Under the action of an applied voltage, the electric field distribution in the composite dielectric is influenced by the characteristics of the dielectric material, wherein the alternating current component of the electric field is inversely proportional to the dielectric constant of the dielectric, and the direct current component is inversely proportional to the conductivity of the dielectric. Under the action of lightning impulse voltage, the electric field distribution in the transformer oil paper is mainly based on alternating current components, and the influence of the dielectric constant of the oil paper composite medium on the insulating property is mainly analyzed in order to simplify calculation.
A large number of indentations are formed in the oil-immersed paper board of the transformer in the manufacturing process, and a large number of concave-shaped oil gaps are formed. Due to the difference between the dielectric constants of the oiled paper, the electric field intensity in the oil gaps in the shape of the Chinese character 'ao' is obviously improved, and discharge is more easily generated in the oil gaps, so that the surface flashover voltage of the oil-immersed paperboard is lower than that of the oil gaps without the paperboard. After the nano particles are added into the transformer oil, the dielectric constant of the transformer oil is changed due to the phenomena of polarization of the nano particles and the like, and the dielectric property of the insulating paper impregnated by the nano oil is correspondingly changed. The change of dielectric constant of the insulating material caused by the modification of the nano particlesThe degree depends not only on the dielectric characteristics of the insulating material itself but also on the kind, concentration, and other characteristics of the added nanoparticles. The relative dielectric constants of the samples used in the test are shown in Table 1, and TiO2The addition of the nano particles increases the relative dielectric constant of the transformer oil from 2.2 to 3.7, while the relative dielectric constant of the oil-impregnated paper board is increased by only 0.2 and from 4.1 to 4.3. The dielectric constant matching coefficient between oil-paper insulation is defined as the ratio of the dielectric constant of oil to the dielectric constant of oil-impregnated paper board, i.e.
Figure BDA0002304439980000061
Wherein epsilonoilAnd εpbThe relative dielectric constants of the transformer oil and the oil-immersed paperboard are respectively. The closer the permittivity match coefficient is to 1, meaning that the permittivities of the two dielectrics are more matched and the electric field will be more evenly distributed between the dielectric materials. Through TiO2The dielectric constant matching coefficient of the oil paper composite medium modified by the nano particles is changed from 0.537 to 0.860, so that TiO in the same insulating structure2The nano-oil bears less electric field strength than pure oil.
TABLE 1 pure oil impregnated paperboard and TiO2Relative dielectric constant of nano oil-immersed paperboard
Figure BDA0002304439980000062
Fig. 4 is a simulation calculation result of the oiled paper insulation steady-state electric field distribution of the needle-plate test electrode structure by using finite element simulation on the premise of neglecting the indentation on the surface of the paperboard, wherein fig. 4(a) is a simulation calculation result of the oiled paper insulation steady-state electric field distribution of the pure oil impregnated paperboard needle-plate test electrode structure, fig. 4(b) is a simulation calculation result of the oiled paper insulation steady-state electric field distribution of the nano oil impregnated paperboard needle-plate test electrode structure, wherein the potential on the needle electrode is 1V, and the plate electrode is grounded. It is clear that the areas of greatest electric field strength are concentrated in the oil gap near the needle electrode.
FIG. 5 shows pure oil impregnated paper board and TiO2Nanometer oil-immersed paperboardThe change of electric field strength along the interface of the paper board, wherein fig. 5(a) is the change of electric field strength on the interface of the pure oil-impregnated paper board, and fig. 5(b) is the change of electric field strength on the interface of the nano oil-impregnated paper board, it can be clearly seen that compared with the pure oil-impregnated paper board, TiO is present2The maximum electric field intensity on the surface of the nano oil-immersed paperboard is much smaller. TiO under needle-plate electrode structure2The maximum electric field intensity of the surface of the nano oil-impregnated paperboard is 406.0V/m, which is only 73.27% of that of the surface of a pure oil-impregnated paperboard (554.1V/m). Therefore, it can be concluded that the electric field distribution between the oiled paper media is more uniform due to the reduced difference in dielectric constant is TiO2One reason for improving the insulating property of the nano oil-impregnated paperboard.
On the other hand, Gauss's law tells us that under the action of an electric field, the interface charge is generated by induction at the interface of the oil-paper medium due to the difference of the dielectric constants of the oil-paper medium,
Figure BDA0002304439980000071
wherein epsilonoilIs the relative dielectric constant of the transformer oil; epsilonpbIs the relative dielectric constant of the oil-impregnated paper board. The magnitude and polarity of the interfacial charge can have an effect on the development of the oil-paper insulation runoff. Because the fluid channel contains a large amount of free charges, the interface charges generate electrostatic force to the free charges in the fluid channel, and the movement of the free charges is influenced. When the dielectric constant of the cardboard is greater than that of the transformer oil, i.e. ε, regardless of the polarity of the free chargepb≥εoilElectrostatic forces provided by the interface charge will attract the free charge towards the oilpaper interface; otherwise if εpb≤εoilElectrostatic forces will provide a repulsive force to the free charge causing it to evolve into the oil.
The influence of the interface charge on the development of the fluid is analyzed by using a mirror charge method, and if a point charge q exists in the transformer oil at the position d away from the paper board, the acting force of the interface charge on the charge is equivalent to the action of the mirror charge q 'at the position d in the paper board on the point charge q'. Magnitude of the mirror charge q' and the resulting electrostatic force
Figure BDA0002304439980000072
Is composed of
Figure BDA0002304439980000073
Figure BDA0002304439980000074
Wherein epsilon0Is the dielectric constant of the vacuum, d is the distance from the point charge in the oil to the oil-paper interface,
Figure BDA0002304439980000075
is a unit direction vector and is directed outwards from the paper board. Substituting the formula (3) into the formula (4) to obtain
Figure BDA0002304439980000081
Wherein
Figure BDA0002304439980000082
Usually the dielectric constant of transformer oil is smaller than that of oil-impregnated paper board (epsilon' < 0), so the generated interface charge can attract the free charge in the fluid flow to the surface of the paper board and move forward along the surface of the paper board under the action of the external electric field, and the discharge along the surface of the paper board is caused to develop. The larger the difference between the dielectric constants of the transformer oil and the oil-immersed paperboard is, the larger the gravitational effect on the flow is. The electrostatic attraction compresses the volume of the stream, so that the charge density in the unit volume of the stream is increased, the electric field at the front end of the head of the stream is increased, and the development of the stream along the surface of the paperboard is accelerated. The introduction of the insulating paper board thus converts the flow in the oil into a faster flow along the surface, reducing the insulating strength of the oil gap.
As can be seen from Table 1, TiO is used2The dielectric properties of the transformer oil and the oil-immersed paper board can be changed by modifying the insulation of the transformer oil paper by the nanoparticles, and the difference between the dielectric constants of the transformer oil and the oil-immersed paper board is reduced. Corresponding to a decrease of ε' from 0.281 to 0.075, the resulting static charge of the interface charge convection currentThe attraction is reduced, so that TiO2The extrusion effect that the surface flow of nanometer oily cardboard received reduces, and the charge density of flow head portion descends, and then has alleviated the electric field strength along cardboard surface flow front end, leads to the flow development speed to descend, and the surface flashover voltage improves.
In conclusion, according to the method for modifying the performance of the transformer oil-paper interface and the nano modified transformer oil-paper, the accumulation phenomenon of space charges at the oil-paper interface is inhibited by adding the nano particles, the dielectric constant difference between the transformer oil and the oil-immersed paper board is relieved, the propagation characteristic of discharge at the interface is changed, the flashover performance of the transformer oil-paper interface is improved, and the technical problem that the insulating performance of the existing transformer oil-paper composite medium is not high is solved.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (8)

1. A method for modifying the performance of an oil-paper interface of a transformer is characterized by comprising the following steps:
spherical TiO is dispersedly added into the interface between transformer oil and insulating oil paper in the transformer2Nanoparticles or Fe3O4The nano particles have the diameter of 20-100 nm.
2. The method for modifying the oil-paper interface performance of the transformer according to claim 1, wherein the spherical TiO is dispersedly added to the interface between the transformer oil and the insulating oil-paper in the transformer2Nanoparticles or Fe3O4Nanoparticles, including any of the following:
adding nano particles at an interface between the transformer oil and the insulating oil paper, and performing vacuum impregnation by using the transformer oil to modify the transformer oil paper interface;
dispersing the nano particles into the transformer oil to obtain the prepared nano modified transformer oil, dipping the insulating paper board in vacuum by using the nano modified transformer oil, and modifying the transformer oil-paper interface to obtain the nano modified transformer oil-paper.
3. The method for modifying the interfacial properties of the transformer oil-paper according to claim 2, wherein nanoparticles are dispersed in the transformer oil, and the ratio of the nanoparticles in the nano-modified transformer oil is 0.01g/L to 0.80 g/L.
4. The method for modifying the interfacial properties of transformer oilpaper according to any one of claims 2 to 3, wherein the moisture content of the prepared nano modified transformer oil is 5 to 8ppm, and the moisture content of the nano modified transformer oilpaper is less than 0.5%.
5. The nano modified transformer oilpaper is characterized in that spherical TiO is uniformly dispersed in the nano modified transformer oilpaper2Nanoparticles or Fe3O4The nano particles have the diameter of 20-100 nm.
6. The nano-modified transformer paper oil according to claim 5, wherein the nano-modified transformer paper oil is prepared by the following method:
dispersing the nanoparticles into the transformer oil to obtain the prepared nano modified transformer oil;
and (3) carrying out vacuum impregnation on the insulating paperboard by using the nano modified transformer oil to obtain the nano modified transformer oil paper.
7. The nano-modified transformer oil paper as claimed in claim 6, wherein nano-particles are dispersed in transformer oil, and the ratio of the nano-particles in the nano-modified transformer oil is 0.01g/L to 0.80 g/L.
8. The nano-modified transformer paper of claim 7, wherein the prepared nano-modified transformer oil has a moisture content of 5-8ppm, and the moisture content of the nano-modified transformer paper is less than 0.5%.
CN201911234210.6A 2019-12-05 2019-12-05 Method for modifying transformer oil paper interface performance and nano modified transformer oil paper Pending CN111270555A (en)

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