WO2019148758A1 - 一种直流盆式绝缘子 - Google Patents

一种直流盆式绝缘子 Download PDF

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Publication number
WO2019148758A1
WO2019148758A1 PCT/CN2018/093140 CN2018093140W WO2019148758A1 WO 2019148758 A1 WO2019148758 A1 WO 2019148758A1 CN 2018093140 W CN2018093140 W CN 2018093140W WO 2019148758 A1 WO2019148758 A1 WO 2019148758A1
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WIPO (PCT)
Prior art keywords
electric field
insulator
basin
basin insulator
flange
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PCT/CN2018/093140
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English (en)
French (fr)
Inventor
何金良
李传扬
张波
林川杰
胡军
李琦
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清华大学
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Application filed by 清华大学 filed Critical 清华大学
Priority to EP18904173.4A priority Critical patent/EP3748653B1/en
Publication of WO2019148758A1 publication Critical patent/WO2019148758A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B17/00—Insulators or insulating bodies characterised by their form
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
    • H02G5/00—Installations of bus-bars
    • H02G5/06—Totally-enclosed installations, e.g. in metal casings
    • H02G5/066—Devices for maintaining distance between conductor and enclosure
    • H02G5/068—Devices for maintaining distance between conductor and enclosure being part of the junction between two enclosures
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B17/00—Insulators or insulating bodies characterised by their form
    • H01B17/42—Means for obtaining improved distribution of voltage; Protection against arc discharges

Definitions

  • the present application relates to the technical field of power technology equipment manufacturing, and in particular to a DC basin insulator.
  • Gas-insulated transmission lines include DC GIL and AC GIL.
  • DC GIL DC GIL
  • AC GIL AC GIL.
  • the electric field in the GIL coaxial cylinder gas gap is constant, the electric field distribution depends on the electrical conductivity of the insulating material, and the electrical conductivity of the insulating material is largely affected by many factors such as temperature, humidity, electric field strength and pressurization time.
  • the metal conductive particles are more likely to migrate and adhere to the surface of the insulator under the action of the electric field; the surface of the insulator will accumulate charge under direct current, which will cause distortion of the electric field on the surface of the insulator, which will become induced.
  • the cause of the unknown flashover of the insulator under DC is caused.
  • the key problem that restricts the DC basin insulator is that there is charge accumulation on the surface under the DC voltage.
  • the accumulation of surface charge will cause local electric field distortion, especially when the DC pot insulator is superimposed with the operating overvoltage or lightning overvoltage, or the polarity is reversed. In the process, the insulator is more prone to flashover.
  • the surface charge accumulation is positively correlated with the surface normal electric field component. Therefore, reducing the normal electric field component can greatly reduce the degree of surface charge accumulation.
  • the purpose of this application is to solve the problem. Therefore, there is a big difference between the environmental insulation characteristics of SF6 gas and AC under DC voltage. Controlling charge accumulation and reducing the amount of surface charge during long-term operation of insulators has become a key technology and difficulty in studying DC GIL insulators. The problem.
  • a DC basin insulator including a central insert, the outer side of the central insert is provided with an epoxy-based aluminum oxide insulating composite, the epoxy three One end of the aluminum oxide insulating composite member is connected to the central insert, and the other end of the epoxy-alumina insulating composite member is connected to the flange;
  • the central insert includes a first intersection, the flange includes a second intersection, and a line between the first intersection and the second intersection is at an angle no greater than 20° to a horizontal plane.
  • the upper end surface of the epoxy-alumina insulating composite member includes a first curved surface, a second curved surface and a third curved surface which are smoothly connected in sequence, and the second curved surface height is lower than the The height of the central insert.
  • the flange is provided with a first mounting hole.
  • the central insert is provided with a second mounting hole.
  • the second mounting hole comprises a screw hole.
  • a shielding ring is further disposed, the shielding ring is disposed in the epoxy-alumina insulating composite, and the shielding ring is connected to the flange.
  • the shield ring is connected to the flange by a block.
  • the insert is welded to the shield ring, the insert being connected to the flange by a screw.
  • the number of the inserts is six.
  • the present application changes the structure of the epoxy-alumina insulating composite member so that the connection between the first intersection on the central insert and the second intersection on the flange is
  • the angle of the horizontal plane is not more than 20°, which greatly reduces the taper of the DC basin insulator. Therefore, under the premise of not increasing the horizontal electric field component, the normal electric field component is greatly reduced, thereby suppressing surface charge accumulation and improving the operational stability of the DC basin insulator under direct current.
  • a shielding ring is arranged in the epoxy-alumina insulating composite member, so that the shielding ring is connected with the flange, and the electric field at the grounding flange, especially the electric field near the wedge-shaped air gap, can be optimized.
  • FIG. 1 is a schematic view showing a first structure of a DC basin insulator according to an embodiment of the present invention
  • FIG. 2 is a schematic view showing a second structure of a DC basin insulator according to an embodiment of the present invention
  • FIG. 3 is a schematic view showing a third structure of a DC basin insulator according to an embodiment of the present invention.
  • FIG. 4 is a schematic view showing the electric field line distribution of a 220 kV AC basin insulator according to an embodiment of the present invention
  • FIG. 5 is a schematic diagram showing electric field line distribution of a 220 kV DC basin insulator according to an embodiment of the present invention
  • FIG. 6 is a schematic view showing a surface electric field modulus curve of an initial state point of a DC basin insulator and a DC basin insulator at a time when a DC voltage of 240 kV is applied according to an embodiment of the present invention
  • FIG. 7 is a schematic view showing a tangential electric field intensity curve of a surface of an AC basin insulator and a DC basin insulator at an initial time point of applying a DC voltage of 240 kV according to an embodiment of the present invention
  • FIG. 8 is a schematic view showing a surface normal electric field intensity curve of an initial state point of a DC pot insulator and a DC basin insulator at a time when a DC voltage of 240 kV is applied according to an embodiment of the present invention
  • FIG. 9 is a schematic view showing a curve of a creeping electric field modulus value of a DC basin insulator and a DC basin insulator in a case where a charge accumulation is saturated after applying 240 kV according to an embodiment of the present invention
  • FIG. 10 is a schematic view showing a creeping tangential electric field intensity curve of an AC basin insulator and a DC basin insulator under charge accumulation after application of 240 kV according to an embodiment of the present invention
  • FIG. 11 is a schematic view showing a normal electric field strength curve along the surface of a DC basin insulator and a DC basin insulator after a charge accumulation saturation after applying 240 kV according to an embodiment of the present invention
  • FIG. 12 is a schematic diagram of a creeping electric field modulus curve of a DC basin insulator and a DC basin insulator in a case where a voltage of 240 kV is reversed to 240 kV under the condition of applying -240 kV charge accumulation saturation according to an embodiment of the present invention
  • FIG. 13 is a schematic view showing a creeping tangential electric field intensity curve of a DC basin insulator and a DC basin insulator in a case where a voltage of 240 kV is reversed to 240 kV under the condition of -240 kV charge accumulation saturation according to an embodiment of the present invention
  • FIG. 14 is a schematic diagram showing a normal electric field strength curve along the surface of a DC basin insulator and a DC basin insulator in the case of applying -240 kV charge accumulation saturation in the embodiment of the present invention
  • 15 is a schematic view showing a curve of creeping surface charge density with time after application of 240 kV on both sides of a DC basin insulator and a DC basin insulator according to an embodiment of the present invention
  • 16 is a schematic diagram of a DC withstand voltage and polarity inversion test platform according to an embodiment of the present invention.
  • FIG. 17 is a schematic diagram of a polarity inversion test voltage application method according to an embodiment of the present invention.
  • Figures 1-20 are: 1-Center Insert, 2-Epoxy Aluminium Oxide Insulation Composite, 3-Flange, 4-First Intersection, 5-Second Intersection, 6-First Arc Face, 7-second curved surface, 8-third curved surface, 9-first mounting hole, 10-second mounting hole, 11-shield ring, 12-insert, 13-screw.
  • GIL Gas-insulated transmission lines
  • DC GIL and AC GIL have little difference in operation and installation.
  • the technical difficulties and differences are mainly reflected in the design of insulation.
  • the electric field distribution depends on the dielectric constant of the insulating material, and the AC GIL has mature design, manufacturing and engineering application experience.
  • a DC basin insulator including a central insert 1 , and an epoxy-based alumina composite member 2 is disposed outside the central insert 1 .
  • One end of the aluminum oxide insulating composite member 2 is connected to the central insert 1, and the other end of the epoxy-alumina insulating composite member 2 is connected to the flange 3;
  • the central insert 1 comprises a first intersection 4, the flange 3 comprising a second intersection 5, the line between the first intersection 4 and the second intersection 5 being at an angle of no more than 20° to the horizontal.
  • the upper end surface of the epoxy-alumina insulating composite member 2 includes a first curved surface 6, a second curved surface 7 and a third curved surface 8 which are smoothly connected in sequence, and the second curved surface 7
  • the height is lower than the height of the central insert 1.
  • the first curved surface 6 is curved downwardly to be convex
  • the second curved surface 7 is curved upwardly to be concave
  • the third curved surface 8 is curved downward to be convex.
  • the flange 3 is provided with a first mounting hole 9 .
  • the central insert 1 is provided with a second mounting hole 10 .
  • the second mounting hole 10 includes a screw hole.
  • the preparation of the DC basin insulator was made by using domestic ellipsoidal ⁇ -alumina as the filler, and the Huntsman epoxy resin used in the domestic medium and low voltage GIS basin insulator was selected.
  • the mixed liquid is injected into the mold of the vacuum casting chamber through the dropping port, and the poured mold is placed in a blast drying oven at 130 ° C for one time curing;
  • One end of the epoxy-alumina insulating composite member 2 is tightly coupled to the center insert 1, and the flange 3 and the other end of the epoxy-alumina insulating composite member 2 are tightly bonded.
  • the key problem that restricts DC basin insulators is that under DC voltage, there will be charge accumulation on the surface, and surface charge accumulation will cause local electric field distortion, especially when DC over-type insulators are superimposed with operating overvoltage or lightning overvoltage, or polarity flipping. In the process, the insulator is more prone to flashover.
  • the surface charge accumulation is positively correlated with the surface normal electric field component. Therefore, reducing the normal electric field component can greatly reduce the degree of surface charge accumulation.
  • the present application comprehensively considers the horizontal electric field and the normal electric field under the direct current environment and polarity reversal, and designs a new DC basin insulator that can be applied in a DC environment.
  • the overall height of the DC basin insulator is reduced, and the height of the epoxy-alumina insulating composite member 2 is lowered by increasing the curvature of the second arc surface 7.
  • a DC basin insulator according to an embodiment of the present invention includes a central insert 1 , and an epoxy-based aluminum oxide insulating composite member 2 is disposed outside the central insert 1 One end of the oxy-alumina insulating composite member 2 is connected to the central insert 1 , and the other end of the epoxy-alumina insulating composite member 2 is connected to the flange 3 ;
  • the central insert 1 comprises a first intersection 4, the flange 3 comprising a second intersection 5, the line between the first intersection 4 and the second intersection 5 being at an angle of no more than 20° to the horizontal.
  • the upper end surface of the epoxy-alumina insulating composite member 2 includes a first curved surface 6, a second curved surface 7 and a third curved surface 8 which are smoothly connected in sequence, and the second curved surface 7
  • the height is lower than the height of the central insert 1.
  • the first curved surface 6 is curved downwardly to be convex
  • the second curved surface 7 is curved upwardly to be concave
  • the third curved surface 8 is curved downward to be convex.
  • the flange 3 is provided with a first mounting hole 9 .
  • the central insert 1 is provided with a second mounting hole 10 .
  • the second mounting hole 10 includes a screw hole.
  • a shielding ring 11 is further disposed, and the shielding ring 11 is disposed in the epoxy-oxygen aluminum oxide insulating composite member 2, and the shielding ring 11 is connected to the flange 3.
  • the shielding ring 11 is connected to the flange 3 by means of an insert 12.
  • the insert 12 is welded to the shield ring 11 and the insert 12 is connected to the flange 3 by means of a screw 13.
  • the insert 12 and the shield ring 11 are ground at the weld to ensure surface smoothness.
  • the number of the inserts 12 is six.
  • the shield ring 11 is made of a spring having a diameter of 1 mm and an elliptical shape with a long axis radius of 10 mm, a short axis radius of 8 mm, and a spring pitch of 2.5 mm.
  • the six inserts 12 are evenly arranged, one end of the insert 12 is welded to the shield ring 11, and the other end of the insert 12 is screwed to the flange 3 by screws 13, of course, the insert 12 and the flange 3 are here. There are many ways to connect, just connect them.
  • the design is based on the simulation assessment criteria provided in Figure 19 and the experimental assessment criteria provided in Figure 20.
  • the electric field is related to the conductivity under the action of the DC field, and the charge accumulation under the DC field will affect the electric field. Therefore, the influence of charge accumulation on the electric field fraction should be considered in the design process.
  • the normal electric field component is reduced by changing its longitudinal height, and the horizontal electric field component of the DC basin insulator is better than the 220kV AC basin insulator horizontal electric field component under the same external excitation source condition.
  • a DC basin insulator shape that meets the requirements.
  • the distance between the AC basin insulators is longer than that of the DC basin insulators.
  • most of the surface regions have electric field lines passing through the surface, that is, their normal electric field components account for a large proportion.
  • the normal electric field component is rarely present in most areas of the shape of the modified DC basin insulator.
  • the electric field modulus of the concave surface is slightly larger than the convex surface, and the maximum value appears on the concave surface of the AC basin insulator, which is about 2.75 kV/mm, and the maximum value of the concave surface of the DC basin insulator can also reach 2.5 kV/mm.
  • the normal component distribution of the middle portion is relatively flat;
  • the normal electric field component of the AC basin insulator is always higher than the normal electric field component of the DC basin insulator.
  • the highest value appears near the high voltage conductor, and the maximum concave and convex surfaces can reach 1.9kV/mm and 1.75kV/ Mm, while the normal component of the concave and convex surfaces of the DC basin insulator is less than 0.75 kV/mm.
  • the DC basin insulator and the AC basin insulator have little difference in electric field modulus after the charge accumulation is saturated, and have the following characteristics:
  • the electric field near the center conductor is relatively high and decreases with increasing distance from the center conductor.
  • the maximum value of the electric field modulus is translated to the ground flange. the trend of;
  • the electric field modulus of the concave surface is slightly larger than the convex surface, and the maximum value appears on the convex surface of the AC basin insulator, which is about 2.75 kV/mm, and the maximum electric field modulus of the DC basin insulator appears on the concave surface, and is not higher than 2.5 kV/mm. .
  • the two kinds of basin insulators have a slightly higher normal electric field component in the vicinity of the central conductor and the grounded casing, and the normal component distribution in the middle portion is relatively flat;
  • the normal electric field component of the AC basin insulator is always higher than the normal electric field component of the DC basin insulator.
  • the highest value appears near the high voltage conductor, and the maximum concave and convex surfaces can reach 1.9kV/mm and 1.75kV/ Mm, while the normal component of the concave and convex surfaces of the DC basin insulator is less than 0.75 kV/mm.
  • the electric field modulus of the concave surface is slightly larger than the convex surface, and the maximum value appears on the convex surface of the AC basin insulator, which has exceeded 3kV/mm.
  • the normal component distribution of the middle portion is relatively flat;
  • the normal electric field component of the AC basin insulator is always higher than the normal electric field component of the DC basin insulator.
  • the highest value appears near the high voltage conductor, and the maximum concave and convex surfaces are located near 2kV/mm, while the DC basin is
  • the maximum values of the normal components of the concave and convex surfaces of the insulator are all lower than 0.75 kV/mm.
  • the charge accumulation saturation time is about 10 hours.
  • the DC basin insulator is superior to the AC basin insulator in the charge accumulation due to the shape improvement.
  • the surface charge density of the concave and convex surfaces of the insulator is less than 10 ⁇ C/m2, and the concave charge density is lower than 5 ⁇ C/m2, while the surface charge density of the concave and convex surface of the AC basin insulator is higher than 10 ⁇ C/m2.
  • the charge density of the convex surface is higher than 18 ⁇ C/m 2 .
  • Routine mechanical simulation Apply 1.5MPa pressure to the concave and convex surfaces to ensure that the bonding position pressure of the insulating material and the insert part is not higher than 20MPa, and the rest position is not higher than 60MPa;
  • the maximum force of the bonding part can reach 14.66MPa, and the maximum pressure value of the remaining part appears at the joint of the grounding flange and the insulating member, the value is 35.02MPa, two The maximum stress value is lower than the allowable pressure; when 1.5MPa force is applied to the convex surface of the DC basin insulator, the maximum force of the bonding part can reach 19.35MPa, and the maximum pressure value of the remaining parts is also the bonding.
  • Routine test adopts the factory test method of domestic 220kV AC basin insulator, including: X-ray flaw detection test, water pressure and airtight test, hot and cold cycle test; at the same time, taking into account the assessment of DC running performance, DC withstand voltage and pole are established.
  • the reversal test is to verify the DC performance of the DC basin insulator by conducting DC withstand voltage and polarity reversal tests on the 220kV AC basin insulator and the DC basin insulator.
  • the purpose of the X-ray flaw detection test is to project the sample by X-ray, and it is possible to observe whether there are pores and cracks inside the sample, and to observe whether the insulating material is tightly bonded to the bonding portion of the insert.
  • Figure 6-11 shows the DC basin insulators that are being sent to the flaw detector for X-ray inspection.
  • the test method for the mechanical properties of industrial basin insulators is accomplished by water pressure and gas tightness tests.
  • the water-pressure test is to carry out a routine test of 1.5 MPa for the pot insulator to be tested.
  • the pressure-resistant time is 5 minutes.
  • the pot-type insulator that is sampled must be able to withstand a water pressure of 2.25 MPa for 1 minute. Partial water leakage, surface cracks and insulator bursting pass the assessment; the airtightness test requires that the container sealed by the basin insulator has a gas leakage rate of less than 1 ⁇ 10-8 cc/s at 20 ° C and a gauge pressure of 0.8 MPa.
  • the thermal cycle test is mainly used to evaluate the internal stress release capability of the basin insulator under the action of cold and heat cycles, and the ability of the physical properties to withstand the thermal cycle.
  • Figure 6-14 shows the photo of the pot insulators being tested in a high-low temperature alternating test chamber. The temperature range is controlled from -70 ° C to 150 ° C.
  • the assessment method for the thermal cycle test is:
  • the DC withstand voltage and polarity reversal test is used to evaluate the performance of the basin insulator in a DC environment.
  • the test platform uses a 550kV AC bushing connected to the 550kV basin insulator through the bottom tee.
  • the other side of the basin insulator is connected with a 550kV to 220kV variable diameter chamber, a basin insulator for DC withstand voltage and the cavity.
  • the other end of the chamber is connected and connected to the high voltage side through a matching central conductor.
  • the other end of the insulator to be tested is connected to the mushroom head shield ball by a guide rod for pressure equalization.
  • Figure 6-15 shows the pressure platform and sample.
  • the chamber was evacuated for 1 hour, filled with SF6 gas to a gauge pressure of 0.4 MPa, ie, the absolute pressure was 0.5 MPa, and the DC voltage was applied through a ⁇ 600 kV DC step-up transformer with a boost rate of 20 kV. /s, ambient temperature is 0 to 5 °C.
  • the DC withstand voltage standard refers to the DC withstand voltage standard for the wall bushing of ⁇ 800kV DC system, the withstand voltage is 1.53 times of the rated operating voltage, and the withstand time is 2 hours.
  • the polarity reversal test standard refers to the requirements of the European standard EN 62199 for DC bushing polarity reversal, and the polarity reversal test voltage conversion is shown in Figure 6-16.
  • the polarity reversal process cannot be realized due to the existing platform.
  • the DC linear boost and the polarity reversal withstand voltage test will be used to evaluate the two.
  • the linear boost test is performed by vacuuming the chamber. 1 hour, pass SF6 to gauge pressure 0.3MPa, that is, the absolute pressure is 0.4MPa, then increase the voltage to flashover at the rate of -20kV/s, record the flash voltage, and continuously add 4 times to the same insulator. Pressure test, voltage recovery time is less than 2 minutes; polarity reversal pressure test method and test procedure are as follows:
  • test chamber is evacuated for 1 hour, and the SF6 is introduced to the gauge pressure of 0.3 MPa, that is, the absolute pressure is 0.4 MPa;
  • the DC basin insulator can pass smoothly for the routine test of AC 220kV basin insulator, which proves that the DC basin insulator can have an equivalent replacement for the existing 220kV AC basin insulator and is applied. Potential possibilities in GIS or GIL.
  • the AC basin insulator and the DC basin insulator are under the polarity reversal withstand voltage test, and the flash voltages are lower than the DC linear boost voltage flashing voltage, wherein the AC basin insulator polarity is reversed.
  • the flash voltage after the turn is relatively lower, and can be reduced from the original 420kV to 440kV to less than 360kV.
  • the linear boosting flash voltage of the DC basin insulator is slightly higher than the linear boosting flash voltage of the AC basin insulator, and the flashover voltage under different withstand voltage times is more stable than the AC basin insulator, and its polarity is reversed along the flash voltage.
  • the value is slightly lower than the linear boost edge flash value, and the withstand voltage values are within 30kV.
  • the present application changes the structure of the epoxy-alumina insulating composite 2 such that the line between the first intersection 4 on the central insert 1 and the second intersection 5 on the flange 3 is at an angle of not more than 20° to the horizontal plane, Reduce the taper of the DC basin insulator. Therefore, under the premise of not increasing the horizontal electric field component, the normal electric field component is greatly reduced, thereby suppressing surface charge accumulation and improving the operational stability of the DC basin insulator under direct current.
  • a shielding ring 11 can be arranged in the epoxy-alumina insulating composite member 2, so that the shielding ring 11 is connected with the flange 3, and the electric field at the grounding flange 3 can be optimized, especially the electric field near the wedge-shaped air gap. .
  • the DC basin insulator can be applied to DC systems of different voltage levels by proportional amplification.
  • DC basin insulators used in DC environments which are manufactured with different filling materials and design ideas, are within the scope of this patent protection.

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Abstract

本申请涉及电力技术设备生产制造技术领域，具体涉及一种直流盆式绝缘子。本申请提供一种直流盆式绝缘子，包括中央嵌件，中央嵌件外侧设置有环氧基三氧化二铝绝缘复合件，环氧基三氧化二铝绝缘复合件的一端与中央嵌件相连接，环氧基三氧化二铝绝缘复合件的另一端与法兰相连接；法兰侧添加了与法兰连接的屏蔽圆环用于控制法兰侧的电场畸变；中央嵌件包括第一交点，法兰包括第二交点，第一交点与第二交点之间的连线与水平面夹角不大于20°。从而使得在不提高水平电场分量的前提下，大大降低法向电场分量，抑制表面电荷积聚，提高直流盆式绝缘子在直流下的运行稳定性。

Description

一种直流盆式绝缘子
本申请要求在2018年02月01日提交中国专利局、申请号为201810101639.7、发明名称为“一种直流盆式绝缘子”的中国专利申请的优先权。
技术领域
本申请涉及电力技术设备生产制造技术领域，具体涉及一种直流盆式绝缘子。
背景技术
气体绝缘金属封闭输电线路(Gas-insulated transmission lines，简称GIL)包括直流GIL和交流GIL。在直流电压下，GIL同轴圆柱气体间隙中电场恒定，电场分布取决于绝缘材料电导率，绝缘材料的电导率又在很大程度上受温度、湿度、电场强度及加压时间等诸多因素的影响，同时，运行过程中，直流下存在的极性反转、瞬态过电压干扰等因素都极大地影响到GIL绝缘系统的稳定性。另外，在恒定直流电场的作用下，金属导电微粒更容易在电场作用下，迁移并附着在绝缘子表面；绝缘子表面在直流下会有电荷积聚，将导致绝缘子表面电场发生畸变，这都将成为诱发直流下绝缘子发生不明沿面闪络的原因。
制约直流盆式绝缘子的关键问题在于直流电压下表面会有电荷积聚，表面电荷积聚将导致局部电场畸变，特别是当直流盆式绝缘子上叠加有操作过电压或者雷电过电压，或者极性翻转的过程中，绝缘子则更容易发生沿面闪络。而直流盆式绝缘子运行过程中，其表面电荷积聚与表面法向电场分量成正相关。因此，降低法向电场分量可以大大降低表面电荷积聚程度。然而，想要降低法向电场分量，势必将会对水平电场分量造成影响，水平电场升高则会导致沿面闪络电压下降，因此，又不能无限制的降低法向场。
直流电压下SF6气体环境绝缘特性和交流下有很大的区别，控制电荷积聚，降低绝缘子长期运行过程中表面电荷量，成为研究直流GIL绝缘子的关键技术及难点。
发明内容
本申请的目的是为了解决因此，直流电压下SF6气体环境绝缘特性和交流下有很大的区别，控制电荷积聚，降低绝缘子长期运行过程中表面电荷量，成为研究直流GIL绝缘子的关键技术及难点的问题。
为此，本发明实施例提供了如下技术方案：一种直流盆式绝缘子，包括中央嵌件，所述中央嵌件外侧设置有环氧基三氧化二铝绝缘复合件，所述环氧基三氧化二铝绝缘复合件的一端与中央嵌件相连接，所述环氧基三氧化二铝绝缘复合件的另一端与法兰相连接；
所述中央嵌件包括第一交点，所述法兰包括第二交点，所述第一交点与所述第二交点之间的连线与水平面夹角不大于20°。
可选地，所述环氧基三氧化二铝绝缘复合件的上端面包括依次光滑连接的第一弧面、第二弧面和第三弧面，所述第二弧面高度低于所述中央嵌件的高度。
可选地，所述法兰上设置有第一安装孔。
可选地，所述中央嵌件上设置有第二安装孔。
可选地，所述第二安装孔包括螺钉孔。
可选地，还包括屏蔽环，所述屏蔽环设置于所述环氧基三氧化二铝绝缘复合件内，所述屏蔽环与所述法兰相连接。
可选地，所述屏蔽环通过镶块与所述法兰连接。
可选地，所述镶块与所述屏蔽环焊接，所述镶块与所述法兰通过螺钉连接。
可选地，所述镶块的数量为6个。
本发明实施例提供的技术方案包括以下有益效果：本申请通过改变环氧基三氧化二铝绝缘复合件的结构使得中央嵌件上第一交点与法兰上第二交点之间的连线与水平面夹角不大于20°，大大降低直流盆式绝缘子的锥度。从而使得在不提高水平电场分量的前提下，大大降低法向电场分量，从而抑制表面电荷积聚，提高直流盆式绝缘子在直流下的运行稳定性。同时，在环氧基三氧化二铝绝缘复合件内设置屏蔽环，使得屏蔽环与法兰相连接，可以优化接地法兰处的电场，特别是楔形气隙附近的电场。
附图说明
为了更清楚地说明本发明实施例的技术方案，下面将对实施例中所需要使用的附图作简单地介绍，显而易见地，对于本领域普通技术人员而言，在不付出创造性劳动性的前提下，还可以根据这些附图获得其他的附图。
图1为本发明实施例中一种直流盆式绝缘子第一结构示意图；
图2为本发明实施例中一种直流盆式绝缘子第二结构示意图；
图3为本发明实施例中一种直流盆式绝缘子第三结构示意图；
图4为本发明实施例中220kV交流盆式绝缘子电场线分布示意图；
图5为本发明实施例中220kV直流盆式绝缘子电场线分布示意图；
图6为本发明实施例中交流盆式绝缘子和直流盆式绝缘子在施加240kV直流电压初始时间点表面电场模值曲线示意图；
图7为本发明实施例中交流盆式绝缘子和直流盆式绝缘子在施加240kV直流电压初始时间点表面切向电场强度曲线示意图；
图8为本发明实施例中交流盆式绝缘子和直流盆式绝缘子在施加240kV直流电压初始时间点表面法向电场强度曲线示意图；
图9为本发明实施例中交流盆式绝缘子和直流盆式绝缘子在施加240kV后电荷积聚饱和情况下的沿面电场模值曲线示意图；
图10为本发明实施例中交流盆式绝缘子和直流盆式绝缘子在施加240kV后电荷积聚饱和情况下的沿面切向电场强度曲线示意图；
图11为本发明实施例中交流盆式绝缘子和直流盆式绝缘子在施加240kV后电荷积聚饱和情况下的沿面法向电场强度曲线示意图；
图12为本发明实施例中交流盆式绝缘子和直流盆式绝缘子在施加-240kV电荷积聚饱和情况下，将电压反转到240kV时刻的沿面电场模值曲线示意图；
图13为本发明实施例中交流盆式绝缘子和直流盆式绝缘子在施加-240kV电荷积 聚饱和情况下，将电压反转到240kV时刻的沿面切向电场强度曲线示意图；
图14为本发明实施例中交流盆式绝缘子和直流盆式绝缘子在施加-240kV电荷积聚饱和情况下，将电压反转到240kV时刻的沿面法向电场强度曲线示意图；
图15为本发明实施例中交流盆式绝缘子和直流盆式绝缘子两侧表面在施加240kV后沿面电荷密度随时间变化曲线示意图；
图16为本发明实施例中直流耐压和极性反转试验平台示意图；
图17为本发明实施例中极性反转试验电压施加方法示意图；
图18为本发明实施例中交流和直流盆式绝缘子沿面闪络和极性反转耐压试验结果；
图19为本发明实施例中提供的仿真考核标准说明图；
图20为本发明实施例中提供的试验考核标准说明图。
图1～20中符号表示为：1-中央嵌件，2-环氧基三氧化二铝绝缘复合件，3-法兰，4-第一交点，5-第二交点，6-第一弧面，7-第二弧面，8-第三弧面，9-第一安装孔，10-第二安装孔，11-屏蔽环，12-镶块，13-螺钉。
具体实施方式
目前，我国新规划的巨型水电工程多选址于西部高原地区的深山峡谷中，且电厂布置方式普遍采用地下厂房形式，电能的送出工程比较困难；另一方面，传统的架空输电线路和交联聚乙烯电力电缆(XPLE)均不能很好的满足在气象条件恶劣、地形环境复杂区域以及电磁干扰水平、自然或人文环境有特殊要求区域的大容量、高可靠性、长距离的直流输电需求；特高压换流站的建设以及设备的连接布置等也都遇到了类似的问题。在这种背景下，综合考虑生态和经济因素，为了满足大规模电能传输系统的发展需求，同时兼顾对土地资源和自然环境的保护，气体绝缘金属封闭输电线路(Gas-insulated transmission lines，简称GIL)应运而生。GIL技术从20世纪70年代开始在世界范围内投入应用，截至2013年6月，80kV-1200kV电压等级的交流GIL在全球范围内投运的总长度已经超过750km，但是这些工程应用都仅限于交流输电领域。
直流GIL和交流GIL在运行，安装等方面差别不大，技术难点和差异性主要体现在绝缘的设计上。在交流电压作用下，电场分布取决于绝缘材料介电常数，且交流GIL已有较为成熟的设计、制造和工程应用经验。
20世纪80年代开始，国内外研究人员对直流GIL的类似产品，即直流气体绝缘开关装置(gas insulated switchgear，GIS)进行了研究，研究重点为金属导电微粒对SF6气体放电的影响，以及绝缘子表面电荷积聚的机理及其对绝缘子闪络的影响等问题。日本首先研制出±500kV GIS并于2000年7月投入运行，然而，运行电压为250kV。近几年来，国内外多家研究机构已经开始围绕直流GIL绝缘子表面电荷行为相继开展研究：湖南大学、华北电力大学、西安交通大学、清华大学等在绝缘子表面电荷测量方法和电荷计算方法等进行了大量研究；天津大学、西安交通大学、华中科技大学、清华大学、同济大学等针对不同种类的绝缘材料，做了一些表面电荷特性的研究，主要针对不同材料表面电荷在直流下的积聚、衰减特性展开，对比不同材料表面电荷运动特性；国外的慕尼黑工业大学、东京大学、苏黎世理工学院、利物浦大学等就绝缘 材料表面电荷积聚及消散规律进行了研究，并结合不同介质物理特性提出了比较系统的仿真方法及结论。
下面通过实施例，并结合附图，对本申请的技术方案作进一步具体的说明。
参见图1，为本发明实施例提供的一种直流盆式绝缘子，包括中央嵌件1，所述中央嵌件1外侧设置有环氧基三氧化二铝绝缘复合件2，所述环氧基三氧化二铝绝缘复合件2的一端与中央嵌件1相连接，所述环氧基三氧化二铝绝缘复合件2的另一端与法兰3相连接；
所述中央嵌件1包括第一交点4，所述法兰3包括第二交点5，所述第一交点4与所述第二交点5之间的连线与水平面夹角不大于20°。
可选地，所述环氧基三氧化二铝绝缘复合件2的上端面包括依次光滑连接的第一弧面6、第二弧面7和第三弧面8，所述第二弧面7高度低于所述中央嵌件1的高度。该第一弧面6向下弯曲呈凸起，第二弧面7向上弯曲呈凹陷，第三弧面8向下弯曲呈凸起。
可选地，所述法兰3上设置有第一安装孔9。
可选地，所述中央嵌件1上设置有第二安装孔10。
可选地，所述第二安装孔10包括螺钉孔。
直流盆式绝缘子的制备选用国产类椭球形α-氧化铝作为填充料，并选取国产中低压GIS盆式绝缘子所用的亨斯曼环氧树脂来制备。
1、将环氧树脂、氧化铝、固化剂按照100：330：38质量比进行称量，并将氧化铝填充料，环氧树脂和模具放入130℃鼓风干燥箱充分预热；这里的环氧树脂型号为CT 5531，固化剂的型号为HY 5533-1。
2、将环氧树脂和填充料放入真空搅拌混料腔，抽真空后，对其进行混合搅拌，充分混合后，将固化剂灌注进入腔体，搅拌充分；
3、将混合液通过下料口注入真空浇注腔室的模具中，并将浇注好的模具放入130℃的鼓风干燥箱进行一次固化12小时；
4、取出模具，将样品取出，重新放入温箱继续完成二次固化，固化时间为16小时；
5、取出样品自然冷却后，对其进行表面处理。
环氧基三氧化二铝绝缘复合件2的一端与中央嵌件1紧密结合，法兰3和环氧基三氧化二铝绝缘复合件2的另一端紧密结合。
制约直流盆式绝缘子的关键问题在于直流电压下，表面会有电荷积聚，表面电荷积聚将导致局部电场畸变，特别是当直流盆式绝缘子上叠加有操作过电压或者雷电过电压，或者极性翻转的过程中，绝缘子则更容易发生沿面闪络。而直流盆式绝缘子运行过程中，其表面电荷积聚与表面法向电场分量成正相关。因此，降低法向电场分量可以大大降低表面电荷积聚程度。然而，想要降低法向电场分量，势必将会对水平电场分量造成影响，水平电场升高则会导致沿面闪络电压下降，因此，又不能无限制的降低法向场。鉴于此，本申请综合考虑直流稳态环境和极性反转作用下的水平电场及法向电场，设计了能够应用于直流环境下的新型直流盆式绝缘子。该直流盆式绝缘子整体高度变小，通过增大第二弧面7的弧度，降低环氧基三氧化二铝绝缘复合件2的 高度。
参见图2～3，为本发明实施例提供的一种直流盆式绝缘子，包括中央嵌件1，所述中央嵌件1外侧设置有环氧基三氧化二铝绝缘复合件2，所述环氧基三氧化二铝绝缘复合件2的一端与中央嵌件1相连接，所述环氧基三氧化二铝绝缘复合件2的另一端与法兰3相连接；
所述中央嵌件1包括第一交点4，所述法兰3包括第二交点5，所述第一交点4与所述第二交点5之间的连线与水平面夹角不大于20°。
可选地，所述环氧基三氧化二铝绝缘复合件2的上端面包括依次光滑连接的第一弧面6、第二弧面7和第三弧面8，所述第二弧面7高度低于所述中央嵌件1的高度。该第一弧面6向下弯曲呈凸起，第二弧面7向上弯曲呈凹陷，第三弧面8向下弯曲呈凸起。
可选地，所述法兰3上设置有第一安装孔9。
可选地，所述中央嵌件1上设置有第二安装孔10。
可选地，所述第二安装孔10包括螺钉孔。
可选地，还包括屏蔽环11，所述屏蔽环11设置于所述环氧基三氧化二铝绝缘复合件2内，所述屏蔽环11与所述法兰3相连接。
可选地，所述屏蔽环11通过镶块12与所述法兰3连接。
可选地，所述镶块12与所述屏蔽环11焊接，所述镶块12与所述法兰3通过螺钉13连接。镶块12与屏蔽环11焊缝处打磨处理，保证表面光滑度。
可选地，所述镶块12的数量为6个。
该屏蔽环11是由弹簧制成，弹簧丝径为1mm，绕成椭圆形，其长轴半径为10mm，短轴半径为8mm，弹簧螺距为2.5mm。
将6个镶块12均匀排布，该镶块12的一端与屏蔽环11焊接，该镶块12的另一端与法兰3通过螺钉13螺接，当然，这里镶块12与法兰3的连接方式可为多种，只要将二者进行连接即可。
对直流盆式绝缘子进行电学和力学的仿真分析
设计依据图19提供的仿真考核标准和图20提供的试验考核标准。
电学仿真
1、基于现有交流盆式绝缘子电场考核仿真分析
交流盆式绝缘子场强设计基准
Figure PCTCN2018093140-appb-000001
参照以上设计基准，对直流盆式绝缘子进行场强计算，其中，计算得到如下结果：
1)屏蔽罩在SF6中的许用场强：E1＝22.46kV/mm；
2)绝缘件嵌件内部允许工作最大场强：E4＝2.45kV/mm；
3)母线表面：E3＝19.71kV/mm；
4)接地外壳表面最大许用场强：E5＝11.21kV/mm；
5)绝缘子表面切向最大许用场强：E6＝11.12kV/mm。
以上结果说明直流盆式绝缘子及其运行环境各处场强均满足220kV交流盆式绝缘子仿真设计要求。
2、考虑直流下电荷积聚因素的仿真分析
不同于交流场作用下电场随介电常数分布的特征，直流场作用下电场与电导率有关，且直流场下电荷积聚将会对电场分部产生影响。因此，在设计过程中要考虑电荷积聚对电场分部的影响。基于交流盆式绝缘子形状，通过改变其纵向高度，降低法向电场分量，同时兼顾在相同外加激励源条件下直流盆式绝缘子水平电场分量优于220kV交流盆式绝缘子水平电场分量的约束条件，设计出满足要求的直流盆式绝缘子形状。
参见图4～5可知交流盆式绝缘子沿面距离要长于直流盆式绝缘子，然而，其大部分的表面区域都存在穿过表面的电场线，也就是说具其法向电场分量占比交大，而形状改良后的直流盆式绝缘子表面大部分区域很少存在法向电场分量。
参见图6～8可知，直流盆式绝缘子同交流盆式绝缘子在电压施加初始阶段的电场强度模值分布还是具有一些相同点，具体如下：
1)靠近中央导体附近的电场强度相对较高，且电场强度幅值随与中央导体距离增加而降低；
2)凹面的电场模值略大于凸面，最大值出现在交流盆式绝缘子的凹面，大约为2.75kV/mm，而直流盆式绝缘子凹面最大值也能够达到2.5kV/mm。
沿面切向场强分布也表现出同电场模值类似的规律。而交流盆式绝缘子的凸面和凹面最大电场分量相差明显增加，且最大值具有向右偏移的趋势，而直流盆式绝缘子二者相差并不是很大；从法向电场分量上来分析，两种盆式绝缘子差距则比较明显，具有如下规律：
1、除中央导体和接地外壳附近具有略高的法向电场分量以外，中间部分的法向分量分布比较平缓；
2、交流盆式绝缘子法向电场分量始终高于直流盆式绝缘子的法向电场分量，其中，最高值出现在高压导体附近，其凹面和凸面的最大值能够达到1.9kV/mm和1.75kV/mm，而直流盆式绝缘子凹面和凸面的法向分量最大值均低于0.75kV/mm。
参见图9～11可知，直流盆式绝缘子同交流盆式绝缘子在电荷积聚出现饱和之后电场模值相差并不大，具备如下特征：
1、靠近中央导体附近的电场强度相对较高，并随与中央导体距离增加而降低，另外，由于载流导体处的同极性电荷注入，导致电场模值最大值有向接地法兰处平移的趋势；
2、凹面的电场模值略大于凸面，最大值出现在交流盆式绝缘子的凸面，大约为2.75kV/mm，而直流盆式绝缘子最大电场模值出现在凹面，且不高于2.5kV/mm。
沿面切向场强分布也表现出同电场模值规律1类似的规律，然而，不同之处在于交流盆式绝缘子的凸面和凹面最大电场分量相差明显增加，而直流盆式绝缘子变化不是很大。从法向电场分量上来分析，二者的区别比较明显，具有如下规律：
1、两种盆式绝缘子除中央导体和接地外壳附近具有略高的法向电场分量以外，中间部分的法向分量分布比较平缓；
2、交流盆式绝缘子法向电场分量始终高于直流盆式绝缘子的法向电场分量，其中，最高值出现在高压导体附近，其凹面和凸面的最大值能够达到1.9kV/mm和1.75kV/mm，而直流盆式绝缘子凹面和凸面的法向分量最大值均低于0.75kV/mm。
参见图12～14可知，1、靠近中央导体附近的电场强度相对较直流电压初始及电荷积聚饱和情况下的值都要有所增加，并随与中央导体距离增加而降低；
2、凹面的电场模值略大于凸面，最大值出现在交流盆式绝缘子的凸面，已经超过了3kV/mm。
针对沿面切向场强分布来讲，也表现出同电场模值规律1类似的规律，然而，不同在于交流盆式绝缘子的凸面和凹面最大电场分量相差明显增加，而直流盆式绝缘子变化不是很大。从法向电场分量上来分析，二者变化比较明显，具有如下规律：
1、除中央导体和接地外壳附近具有略高的法向电场分量以外，中间部分的法向分量分布比较平缓；
2、交流盆式绝缘子法向电场分量始终高于直流盆式绝缘子的法向电场分量，其中，最高值出现在高压导体附近，其凹面和凸面的最大值位于2kV/mm附近，而直流盆式绝缘子凹面和凸面的法向分量最大值均低于0.75kV/mm。
参见图15可知，可见，二者电荷积聚饱和时间大致均为10个小时左右，电荷积聚稳定后，由于形状上的改良，直流盆式绝缘子在电荷积聚方面明显优于交流盆式绝缘子，直流盆式绝缘子凹面和凸面的表面电荷密度均低于10μC/m2，其凹面的电荷密度更是低于了5μC/m2，而交流盆式绝缘子凹面和凸面的表面电荷密度均高于10μC/m2，其凸面的电荷密度更是高于了18μC/m2。
力学仿真
基于现有220kV交流盆式绝缘子力学仿真分析方法，设定直流盆式绝缘子力学仿真分析准则如下：
1、例行力学仿真：对凹面及凸面施加1.5MPa压力，确保绝缘材料同嵌件部位的粘接位置压力不高于20MPa，其余位置不高于60MPa；
2、破坏力学仿真：对凹面及凸面施加2.25MPa压力，确保绝缘材料同嵌件部位的粘接位置压力不高于35MPa，其余位置不高于90MPa。
当1.5MPa作用力施加于直流盆式绝缘子凹面时，粘接部位最大受力可以达到14.66MPa，而其余部位最大压力值出现在接地法兰同绝缘件的连接部位，其值为35.02MPa，二者均低于许用压力下的最大受力值；当1.5MPa作用力施加于直流盆式绝缘子凸面时，粘接部位最大受力可以达到19.35MPa，而其余部位最大压力值同样为该粘接部位的19.35MPa；当2.25MPa作用力施加于直流盆式绝缘子凹面时，粘接部位最大受力可以达到21.99MPa，而其余部位最大压力值出现在接地法兰同绝缘件的连接部位，其值为52.54MPa，二者均低于许用压力下的最大受力值；当2.25MPa作用力施 加于直流盆式绝缘子凸面时，粘接部位最大受力可以达到23.09MPa，而其余部位最大压力值同样为该粘接部位的23.09MPa。以上分析说明，本文设计的直流盆式绝缘子力学性能能够满足交流220kV盆式绝缘子的要求，这也就是说，将其替代交流220kV盆式绝缘子之后，其力学性能能够满足运行可靠性的要求。
例行试验设置
例行试验采用国产220kV交流盆式绝缘子出厂前试验方法，包括：X光探伤试验，水压及气密试验，冷热循环试验；同时，兼顾直流运行性能的考核，制定了直流耐压及极性反转试验，即通过对220kV交流盆式绝缘子同直流盆式绝缘子进行直流耐压及极性反转试验，验证直流盆式绝缘子在直流性能方面的优越性。
X光探伤试验
X光探伤试验目的为通过X射线投射样品，可以观察到样品内部是否存在气孔，裂纹，并能够观察绝缘材料同嵌件粘接部位是否紧密结合。试验过程中，样品通过X光探伤机进行观察，其中，投影面积10×10cm的范围允许缺陷为Φ＝1.0-1.5mm，且深度低于0.5mm的缺陷不多于4个。图6-11为正在送入探伤机准备进行X光探伤试验的直流盆式绝缘子。
水压及气密试验
工业用盆式绝缘子的力学性能试验考核方法是通过水压和气密试验来完成的。其中，水压试验对待考核的盆式绝缘子进行1.5MPa的例行试验，耐压时间为5分钟，对抽检出的盆式绝缘子需要能够耐受2.25MPa的水压1分钟，耐压过程中不出现局部漏水，表面裂痕及绝缘子炸裂为通过考核；气密性试验要求盆式绝缘子密封的容器在20℃，表压0.8MPa下的漏气率小于1×10-8cc/s。
冷热循环试验
冷热循环试验主要用于考核盆式绝缘子在冷热循环作用下的内部应力释放能力，以及物理性状耐受冷热循环作用的能力。图6-14所示为正在进行试验的盆式绝缘子放入高低温交变试验箱的照片，温度范围控制在-70℃至150℃程控可调。
冷热循环试验考核方式为：
1、将盆式绝缘子放入高低温交变试验箱中，调节温度为-30±5℃，持续时间为4小时；
2、将绝缘子放回室温2小时；
3、将盆式绝缘子放入高低温交变试验箱中，调节温度为110±5℃；
4、重复步骤1-3共10个循环；
5、取出测试完毕的盆式绝缘子，观察其表面及内部无裂纹及其它损伤即通过试验。
直流耐压及极性反转试验
参见图16，直流耐压与极性反转试验用于考核盆式绝缘子在直流环境下的运行性能。试验平台采用一根550kV交流套管，通过底部的三通与550kV盆式绝缘子连接，该盆式绝缘子另一侧连接有550kV转220kV变径腔室，直流耐压用的盆式绝缘子与该腔室另一端连接，并通过配套的中央导体进行高压端的连接。待测绝缘子另一端通过一根导杆连接蘑菇头屏蔽球进行均压。耐压平台及样品示意图如图6-15所示。试验过程中，腔室抽真空时间为1小时，充入SF6气体至表压为0.4MPa，即绝对压力为0.5MPa， 直流电压通过一台±600kV直流升压变压器进行施加，升压速率为20kV/s，环境温度为0到5℃。
参见图17，由于没有直流盆式绝缘子考核标准，直流耐压标准参考±800kV直流系统用穿墙套管直流耐压标准，耐受电压为额定运行电压的1.53倍，耐受时间2小时，因此，选取直流耐压考核值为UT＝1.53UN＝245kV，耐压时间为2小时。
极性反转试验标准参考欧标EN 62199关于直流套管极性反转的要求，极性反转试验电压转换如图6-16所示，另外，由于现有平台无法实现极性反转过程中时间尽可能短，且要低于2分钟的要求，因此，相应提高施加电压幅值，进而提高考核试验严酷性，施加电压值为1.5UN＝240kV。
与交流220kV盆式绝缘子对比试验
为了对比直流盆式绝缘子同220kV交流盆式绝缘子在直流作用下性能，将通过直流线性升压及极性反转耐压试验对二者进行考核，其中，线性升压考核通过对腔室抽真空1小时，通入SF6至表压0.3MPa，也就是绝对压力0.4MPa后，以-20kV/s的速率升高电压至沿面闪络发生，记录沿闪电压，连续对同一个绝缘子进行4次加压测试，电压恢复时间小于2分钟；极性反转耐压考核方法及试验流程如下：
1、对试验腔室抽真空1小时，通入SF6至表压0.3MPa，也就是绝对压力0.4MPa；
2、以-20kV/s的速率升高电压至-300kV，保持该电压90分钟后，将直流发生器极性进行翻转，以20kV/s的速率升高电压至沿面闪络发生，记录沿闪发生时的电压。
通过X光探伤试验可得出直流盆式绝缘子内部材料混合均匀，无局部密集区域；嵌件周围材料贴合紧密，无明显分层或者亮线存在，这说明由于样品尺寸的改变及内部均压屏蔽件的改变并未对直流绝缘子的浇注及固化过程产生影响。冷热循环试验的顺利通过说明了直流盆式绝缘子在不同外界温度交替变化影响下物理性状稳定，表明其能够抵御运行过程中由于外界温度和导体温度变化带来的不同材料热特性不同而产生的附加应力作用。水压试验及气密试验的通过表明了绝缘子的力学性能及密封性能能够满足工业化GIS或者GIL对密封绝缘件的要求。
例行试验名称及结果
Figure PCTCN2018093140-appb-000002
基于对以上试验结果分析可知，对于交流220kV盆式绝缘子的例行试验，直流盆式绝缘子均能够顺利通过，这证明了直流盆式绝缘子能够具有等效替代现有220kV交流盆式绝缘子并应用于GIS或者GIL中的潜在可能性。
直流试验名称及结果
Figure PCTCN2018093140-appb-000003
结果显示，直流耐压及极性反转试验均能顺利通过。
参见图18可知，交流盆式绝缘子和直流盆式绝缘子在极性反转耐压考核下，二者沿闪电压均低于直流线性升压的沿闪电压，其中，交流盆式绝缘子极性反转后的沿闪电压相对而言下降更多，能够由原来的420kV到440kV下降到低于360kV。直流盆式绝缘子线性升压沿闪电压略高于交流盆式绝缘子线性升压沿闪电压，且不同耐压次数下的闪络电压比交流盆式绝缘子更稳定，其极性反转沿闪电压值略微低于线性升压沿闪值，二者耐压值相差在30kV以内。
本申请通过改变环氧基三氧化二铝绝缘复合2的结构使得中央嵌件1上第一交点4与法兰3上第二交点5之间的连线与水平面夹角不大于20°，大大降低直流盆式绝缘子的锥度。从而使得在不提高水平电场分量的前提下，大大降低法向电场分量，从而抑制表面电荷积聚，提高直流盆式绝缘子在直流下的运行稳定性。同时，可在环氧基三氧化二铝绝缘复合件2内设置屏蔽环11，使得屏蔽环11与法兰3相连接，可以优化接地法兰3处的电场，特别是楔形气隙附近的电场。
该直流盆式绝缘子可通过等比放大，应用于不同电压等级的直流系统中。另外，采用不同填充材料及设计思路制造的应用于直流环境下的直流盆式绝缘子，都属于该专利保护范围之内。
以上所述仅是本发明实施例的具体实施方式，使本领域技术人员能够理解或实现本发明。对这些实施例的多种修改对本领域的技术人员来说将是显而易见的，本文中所定义的一般原理可以在不脱离本发明的精神或范围的情况下，在其它实施例中实现。因此，本发明将不会被限制于本文所示的这些实施例，而是要符合与本文所公开的原理和新颖特点相一致的最宽的范围。
应当理解的是，本申请并不局限于上面已经描述并在附图中示出的内容，并且可以在不脱离其范围进行各种修改和改变。本申请的范围仅由所附的权利要求来限制。

Claims (9)

  1. 一种直流盆式绝缘子，其特征在于，包括中央嵌件(1)，所述中央嵌件(1)外侧设置有环氧基三氧化二铝绝缘复合件(2)，所述环氧基三氧化二铝绝缘复合件(2)的一端与中央嵌件(1)相连接，所述环氧基三氧化二铝绝缘复合件(2)的另一端与法兰(3)相连接；
    所述中央嵌件(1)包括第一交点(4)，所述法兰(3)包括第二交点(5)，所述第一交点(4)与所述第二交点(5)之间的连线与水平面夹角不大于20°。
  2. 如权利要求1所述的直流盆式绝缘子，其特征在于，所述环氧基三氧化二铝绝缘复合件(2)的上端面包括依次光滑连接的第一弧面(6)、第二弧面(7)和第三弧面(8)，所述第二弧面(7)高度低于所述中央嵌件(1)的高度。
  3. 如权利要求2所述的直流盆式绝缘子，其特征在于，所述法兰(3)上设置有第一安装孔(9)。
  4. 如权利要求3所述的直流盆式绝缘子，其特征在于，所述中央嵌件(1)上设置有第二安装孔(10)。
  5. 如权利要求4所述的直流盆式绝缘子，其特征在于，所述第二安装孔(10)包括螺钉孔。
  6. 如权利要求1～5中任一项所述的直流盆式绝缘子，其特征在于，还包括屏蔽环(11)，所述屏蔽环(11)设置于所述环氧基三氧化二铝绝缘复合件(2)内，所述屏蔽环(11)与所述法兰(3)相连接。
  7. 如权利要求6所述的直流盆式绝缘子，其特征在于，所述屏蔽环(11)通过镶块(12)与所述法兰(3)连接。
  8. 如权利要求7所述的直流盆式绝缘子，其特征在于，所述镶块(12)与所述屏蔽环(11)焊接，所述镶块(12)与所述法兰(3)通过螺钉(13)连接。
  9. 如权利要求8所述的直流盆式绝缘子，其特征在于，所述镶块(12)的数量为6个。
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CN112613215A (zh) * 2020-12-23 2021-04-06 平高集团有限公司 一种盆式绝缘子优化方法
CN114188111A (zh) * 2021-11-08 2022-03-15 南方电网科学研究院有限责任公司 一种gis/gil环氧树脂绝缘子的表面处理方法
CN114188111B (zh) * 2021-11-08 2024-04-26 南方电网科学研究院有限责任公司 一种gis/gil环氧树脂绝缘子的表面处理方法
CN115629130A (zh) * 2022-12-21 2023-01-20 国网天津市电力公司电力科学研究院 盆式绝缘子残余应力的成像方法、系统及试块制备方法
CN116859191A (zh) * 2023-06-21 2023-10-10 武汉大学 直流盆式绝缘子电场控制阈值计算系统和方法

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