A glue-air composite optical fiber insulator for UHV DC FOCT

Abstract

The present invention belongs to the technical field of ultra-high voltage direct current power transmission and distribution and electric power equipment manufacturing, and specifically relates to a glue-gas composite optical fiber insulator for ultra-high voltage direct current FOCT. It comprises a core rod, and the two ends of the core rod are respectively provided with low-voltage end hardware and high-voltage end hardware; wherein the core rod located at the high-voltage end hardware part is provided with an insulating filling glue layer, and the height of the insulating filling glue layer is greater than the height of the high-voltage end hardware; the core rod away from the high-voltage end hardware part is provided with a gas insulation layer; the core rod is axially penetrated with an optical fiber channel, and an optical fiber is penetrated in the optical fiber channel; a plurality of insulating support sheets are provided along the axial direction of the optical fiber channel and in the optical fiber channel. The present invention uses an insulating filling material and air to match the insulation scheme, and the pouring height of the insulating filling material is relatively low, and the corresponding volume change after thermal expansion is also relatively small, and there is no need to reserve thermal expansion space for it, which solves the problems caused by thermal expansion and contraction of the insulating filling material and the problem of high field strength at the high-voltage end.

Description

Technical Field

[0001] The invention belongs to the technical field of ultra-high voltage direct current power transmission and distribution and electric power equipment manufacturing, and in particular relates to a glue-gas composite optical fiber insulator for ultra-high voltage direct current FOCT. Background Art

[0002] As new grid technologies mature, a large number of DC projects have begun to be built and put into operation, and the application of all-optical current transformers has become more extensive and mature. All-optical current transformers, abbreviated as FOCT, are called Fiber Optic Current Transformer in English. FOCT has the advantages of wide frequency response range, high measurement accuracy, no electromagnetic interference, small size, light weight, etc., and has been favored and valued by UHV DC transmission projects.

[0003] Fiber optic insulators are key components of all-fiber optic current transformers in UHV DC and flexible DC projects, and their insulation level has an important impact on the safe and stable operation of UHV DC transmission systems. However, due to their appearance, hardware structure, and low conductivity of insulating filling materials, fiber optic insulators have concentrated electric fields at the high-voltage and low-voltage ends, which can easily introduce defects during thermal expansion and contraction. In addition, there are serious interface problems in the multi-layer composite dielectric structure inside the fiber optic insulator, which can easily lead to discharge failures and poor operational reliability.

[0004] At present, the existing optical fiber insulators mainly include optical fiber embedded type and filling material casting type. The insulation level of the optical fiber embedded type is low and the preparation process is complicated. The insulating filling material in the filling material casting type optical fiber insulator needs to be set with thermal expansion space, which not only complicates the structure of the optical fiber insulator, but also increases the difficulty of equipment sealing and manufacturing. Most of the existing optical fiber insulators use the insulating filling material method, that is, the technical solution of using the insulating filling material to fill the entire epoxy core. However, the axial size of the UHV DC optical fiber insulator is large, and the liquid level of the internal insulating filling material will rise or even overflow during the thermal expansion process. Therefore, when the insulating filling material in the filling material casting type optical fiber insulator is used for insulation, it is necessary to reserve thermal expansion space for it. This will not only complicate the structure of the optical fiber insulator, increase the difficulty and manufacturing cost of the optical fiber insulator, and increase the difficulty of equipment sealing, but also the insulating filling material may be involved in the gas during the thermal expansion and contraction process, making it easier to produce defects inside the optical fiber insulator. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a glue-gas composite optical fiber insulator for UHV DC FOCT. The structure adopts a solution of insulating filling material and air for insulation, that is, the insulating filling material is filled in the high-voltage end part to form an insulating filling glue layer, and the remaining part is insulated with gas to form a gas insulation layer, and the optical fiber is fixed with a support sheet, which optimizes the insulation structure of the optical fiber insulator, can effectively even the electric field inside the power equipment, so that the maximum field strength of each key part can be effectively controlled, and no thermal expansion space is required to reduce the size of the equipment and solve safety hazards, and has the advantages of simple structure, low manufacturing cost and high insulation level.

[0006] The present invention solves the above technical problems through the following technical solutions.

[0007] The object of the present invention is to provide a glue-air composite optical fiber insulator for ultra-high voltage direct current FOCT, comprising a core rod, wherein the two ends of the core rod are respectively sleeved with a low-voltage end hardware and a high-voltage end hardware; the interior of the core rod is a glue-air composite insulation structure, wherein an insulating filling glue layer is provided in the core rod located at the high-voltage end hardware part, and the height of the insulating filling glue layer is greater than the height of the high-voltage end hardware, 10 13 Ω·m<The resistivity of the insulating filling layer<10 14 Ω·m, used to control the local high field strength near the high-voltage end; a gas insulation layer is provided in the core rod away from the hardware part of the high-voltage end;

[0008] The core rod is provided with an optical fiber channel axially therethrough, and an optical fiber is provided through the optical fiber channel;

[0009] A plurality of insulating support sheets are arranged along the axial direction of the optical fiber channel and inside the optical fiber channel, and are used for limiting and fixing the optical fiber.

[0010] Furthermore, in the above-mentioned glue-air composite optical fiber insulator for UHV DC FOCT, the insulating filling glue layer 10 is an organic silicone gel layer. -4 / ℃<Thermal expansion coefficient of silicone gel layer<10 -3 / ℃, -5gf·s / m 2 <Adhesion of silicone gel layer<-4gf·s / m 2 The weight ratio of component A and component B of the silicone gel layer needs to be adjusted so that the thermal expansion coefficient of the gel under this ratio is greater than 10 -4 / ℃ and less than 10 -3 / ℃, resistivity greater than 10 13 Ω·m is less than 10 14 Ω·m, -5gf·s / m 2 <Adhesion of silicone gel layer<-4gf·s / m 2 .

[0011] Furthermore, in the above-mentioned glue-air composite optical fiber insulator for UHV DC FOCT, the insulating filling glue layer is filled inside the core rod of the high-voltage end hardware part. According to the internal electric field optimization effect, the height of the insulating filling glue layer is 50mm~80mm greater than the height of the high-voltage end hardware.

[0012] Furthermore, the above-mentioned glue-air composite optical fiber insulator for UHV DC FOCT is provided with a plurality of silicone rubber outer umbrella skirts around the outer wall of the core rod, and the plurality of silicone rubber outer umbrella skirts are distributed along the axial direction of the core rod to protect the core rod and the optical fiber insulator from environmental and climate influences.

[0013] Furthermore, in the above-mentioned glue-gas composite optical fiber insulator for ultra-high voltage direct current FOCT, the optical fiber includes a plurality of polarization-maintaining optical fibers, all of which are evenly spaced on the insulating support sheet along the circumferential direction of the insulating support sheet, each polarization-maintaining optical fiber is axially arranged in the optical fiber channel, and each polarization-maintaining optical fiber is provided with a tight sheath.

[0014] Furthermore, in the above-mentioned glue-air composite optical fiber insulator for UHV DC FOCT, the resistivity of the insulating support sheet is 1×10 14 Ω·m, the material of the insulating support sheet is polytetrafluoroethylene, the radius of the insulating support sheet is smaller than the inner diameter of the core rod, and the thickness is 2mm.

[0015] Furthermore, in the above-mentioned glue-gas composite optical fiber insulator for UHV DC FOCT, the outer wall of the low-voltage end hardware is provided with a low-voltage end equalizing ring, and the low-voltage end equalizing ring is a single-ring structure.

[0016] Furthermore, in the above-mentioned glue-gas composite optical fiber insulator for UHV DC FOCT, the outer wall of the high-voltage end hardware is provided with a high-voltage end equalizing ring, and the high-voltage end equalizing ring is a double-ring structure.

[0017] Furthermore, the above-mentioned glue-gas composite optical fiber insulator for ultra-high voltage direct current FOCT has a direct current transmission of ±800kV.

[0018] Furthermore, in the above-mentioned glue-gas composite optical fiber insulator for ultra-high voltage direct current FOCT, the material used to prepare the core rod is epoxy glass fiber composite material.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] (1) The present invention proposes a new type of fiber optic insulator structure with glue-gas composite for UHV DC FOCT, in which the high-voltage end is filled with insulating filling material to form an insulating filling glue layer, the remaining part is insulated with gas to form a gas insulation layer, and the optical fiber is fixed with an insulating support sheet. This solution can effectively even out the electric field inside the power equipment, so that the maximum field strength of each key part can be effectively controlled, effectively solve the problem of high field strength at the high-voltage end of the fiber optic insulator, improve the operational reliability of the fiber optic insulator, and reduce the difficulty of manufacturing the fiber optic insulator, with high insulation level and low production cost.

[0021] (2) In the solution of using insulating filling material and air for insulation proposed by the present invention, the pouring height of the insulating filling material is relatively low, and the corresponding volume change after thermal expansion is also relatively small, so there is no need to reserve space for thermal expansion. Compared with the technical solution of traditional optical fiber insulators that mostly use the entire epoxy core to be filled with insulating filling material, the dimensional margin is larger and the probability of gas being involved during thermal expansion and contraction is reduced, which effectively solves the technical problems caused by the thermal expansion and contraction of the insulating filling material and provides an important method and approach for the independent research and development of UHV DC optical fiber insulators.

[0022] (3) The insulating filling material used in the optical fiber insulator of the present invention is R-895 silicone gel, which has good adhesion, weather resistance, aging resistance and electrical insulation performance, and good self-recovery after thermal expansion and contraction, thereby avoiding the phenomenon that traditional optical fibers produce air gaps due to colloid changes during thermal expansion and contraction, thereby causing local discharge at insulation defects and even causing discharge failures. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The figure is a schematic diagram of the overall structure of the glue-air composite optical fiber insulator for the UHV DC FOCT of the present invention.

[0024] Figure 2 It is a schematic diagram of the relative position relationship between the optical fiber and the insulating support sheet in the glue-air composite optical fiber insulator of the present invention.

[0025] Figure 3 It is a schematic diagram of the double-ring structure of the high-pressure end equalizing ring of the present invention.

[0026] Figure 4 It is a schematic diagram of the structure of the low-pressure end equalizing ring of the present invention.

[0027] Illustration Description:

[0028] 1- low voltage end fittings, 2- low voltage end equalizing ring, 3- high voltage end fittings, 4- high voltage end equalizing ring, 5- silicone rubber outer skirt, 6- optical fiber, 7- insulating support sheet, 8- core rod, 9- gas insulation layer, 10- insulating filling rubber layer, 11- first high voltage end equalizing ring, 12- second high voltage end equalizing ring, 13- optical fiber insulator. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] It should be noted that the professional terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention. Certain words are used in the present invention to refer to specific components. Those skilled in the art should understand that technicians will use different nouns to refer to the same component. The present invention does not distinguish between components by the difference in nouns, but by the difference in the functions of the components. As mentioned throughout the specification and claims, "including" is an open term and should be understood as "including but not limited to".

[0031] Due to its appearance, hardware structure and low conductivity of insulating filling materials, traditional optical fiber insulators have concentrated electric fields at the high-voltage and low-voltage ends. In addition, the multi-layer composite dielectric structure inside the optical fiber insulator has serious interface problems, which can easily lead to discharge failures.

[0032] The existing optical fiber insulators currently use a high proportion of insulating filling materials, and the manufacturing process mostly uses a technical solution of completely filling the epoxy core with insulating filling materials. However, the axial dimension of the UHV DC optical fiber insulator is large, and the liquid level of the internal insulating filling material will rise or even overflow during the thermal expansion process. Therefore, when pouring the insulating filling material into the optical fiber insulator for insulation, it is necessary to reserve thermal expansion space for it. This will not only complicate the structure of the optical fiber insulator, increase the difficulty and manufacturing cost of the optical fiber insulator, and increase the difficulty of equipment sealing, but the insulating filling material may also be drawn into gas during the thermal expansion and contraction process, making it easier for defects to occur inside the optical fiber insulator.

[0033] Based on the above problems, the present invention provides a glue-air composite optical fiber insulator for UHV DC FOCT, such as Figure 1 As shown, it includes a core rod 8, and the two ends of the core rod 8 are respectively sleeved with a low-voltage end hardware 1 and a high-voltage end hardware 3; the core rod 8 has a rubber-air composite insulation structure, wherein the core rod 8 located at the high-voltage end hardware 3 is provided with an insulating filling rubber layer 10, and the height of the insulating filling rubber layer 10 is greater than the height of the high-voltage end hardware 3, 10 13 Ω·m<The resistivity of the insulating filling layer<10 14Ω·m, used to control the local high field strength near the high-voltage end; a gas insulation layer 9 is provided in the core rod 8 away from the high-voltage end hardware 3 to increase the breakdown field strength and to make the internal electric field uniform, so that the maximum field strength at each position can be effectively controlled; an optical fiber channel is provided axially through the core rod 8, and an optical fiber 6 is provided through the optical fiber channel; a plurality of insulating support sheets 7 are provided along the axial direction of the optical fiber channel and in the optical fiber channel to limit and fix the optical fiber 6.

[0034] The present invention fills an insulating filling glue layer 10 inside the core rod 8 located at the high-voltage end hardware 3. Except for the high-voltage end portion, the insulating filling glue layer 10 is filled to control the local high field strength near the high-voltage end. A gas insulation layer 9 is provided inside the core rod 8 far away from the high-voltage end hardware 3, that is, dry gas insulation is used in the middle section and the low-voltage end of the optical fiber insulator, and the optical fiber is limited and fixed by using the insulating support sheet 7 structure, so that the core rod 8 has a glue-gas composite insulation structure, which can make the field strength of each key part within the control value, that is, the insulating filling material is filled in the high-voltage end portion to form the insulating filling glue layer 10, and the remaining portion is filled with gas to form the gas insulation layer 9 and the optical fiber 6 is fixed by using the insulating support sheet 7. This solution can not only improve the breakdown field strength of the equipment, but also effectively make the electric field inside the power equipment uniform, so that the maximum field strength of each key part can be effectively controlled, and the problem of local high field strength at the high-voltage end of the optical fiber insulator is effectively solved. The casting height of the insulating filling glue layer 10 is relatively low, and the corresponding volume change after thermal expansion is also relatively small, so there is no need to reserve thermal expansion space for it. Compared with the technical solution of traditional optical fiber insulators that mostly use insulating filling materials to fill the entire epoxy core, the dimensional margin is larger, and the probability of gas being involved in the process of thermal expansion and contraction is reduced, which effectively solves the technical problems caused by the thermal expansion and contraction of the insulating filling materials, and provides an important method and approach for the independent research and development of ultra-high voltage DC optical fiber insulators.

[0035] The invention is further described below through specific examples.

[0036] Example

[0037] The present invention provides a glue-air composite optical fiber insulator for ultra-high voltage direct current FOCT, such as Figure 1 As shown, it includes a core rod 8, and the two ends of the core rod 8 are respectively sleeved with a low-voltage end hardware 1 and a high-voltage end hardware 3; the core rod 8 has a rubber-air composite insulation structure, wherein the core rod 8 located at the high-voltage end hardware 3 is provided with an insulating filling rubber layer 10, and the height of the insulating filling rubber layer 10 is greater than the height of the high-voltage end hardware 3, 10 13 Ω·m<the resistivity of the insulating filling glue layer 10<10 14Ω·m, used to control the local high field strength near the high-voltage end; a gas insulation layer 9 is provided in the core rod 8 away from the high-voltage end hardware 3 to improve the breakdown field strength and uniform internal electric field, so that the maximum field strength at each position can be effectively controlled; an optical fiber channel is provided axially through the core rod 8, and an optical fiber 6 is provided in the optical fiber channel; a plurality of insulating support sheets 7 are provided along the axial direction of the optical fiber channel and in the optical fiber channel, which are used to limit and fix the optical fiber 6. Among them, the direct current transmission of the glue-gas composite optical fiber insulator for ultra-high voltage direct current FOCT is ±800kV, that is, the optical fiber insulator is a ±800kV ultra-high voltage direct current optical fiber insulator, and the material for preparing the core rod 8 is epoxy glass fiber composite material. The low-voltage end hardware 1 is a low-voltage end metal flange, and the high-voltage end hardware 3 is a high-voltage end metal flange, that is, the low-voltage end metal flange and the high-voltage end metal flange are respectively sleeved at the two ends of the core rod 8, and are fixed to the two ends of the core rod 8 by bolts, and the insulating filling glue layer 10 is filled inside the core rod at the high-voltage end, and the filling height exceeds the upper part of the high-voltage end flange interface.

[0038] In a specific embodiment, in order to optimize the field intensity distribution inside the FOCT, the resistivity of the insulating filling glue material should be within 10 13 Ω·m level, in order to ensure that the insulating filling glue does not have fluidity under the actual operating temperature conditions, and to maintain close adhesion with the optical fiber, and no air gap and optical fiber bending will occur after thermal expansion and contraction, the thermal expansion coefficient of the insulating filling material should be within 10 -4 / ℃ level, the adhesion value should not be greater than -4gf·s. More specifically, the two-component silicone gel layer is an R-895 silicone gel material layer purchased from Blue Morning Chemical Research and Design Institute Co., Ltd. The weight ratio of component A and component B in the R-895 silicone gel material is 10:8. The thermal expansion coefficient of the colloid under this ratio is 6.17×10 -4 / ℃, hardness is 6.47gf, adhesion is -4.88gf·s / m 2 , the resistivity is 4.24×10 13 Ω·m. It has good adhesion, weather resistance, aging resistance and electrical insulation performance, and good self-recovery after thermal expansion and contraction, avoiding the phenomenon of local discharge at insulation defects and even discharge failure caused by air gaps caused by colloid changes during thermal expansion and contraction of traditional optical fibers.

[0039] In a specific embodiment, the insulating filling glue layer 10 is filled inside the core rod of the high-voltage end hardware part. According to the internal electric field optimization effect, the height of the insulating filling glue layer 10 is 50mm~80mm greater than the height of the high-voltage end hardware. More specifically, the height of the insulating filling glue layer 10 is 60mm beyond the upper part of the high-voltage end flange interface, which can effectively realize the optimization control of the local high field strength at the high-voltage end of the composite optical fiber insulator. The pouring height of the insulating filling material is relatively low, and the corresponding volume change after thermal expansion is also relatively small, so there is no need to reserve thermal expansion space for it. Compared with the technical solution of traditional optical fiber insulators that mostly use the insulating filling material to fill the entire epoxy core, the dimensional margin is larger, and the probability of gas being involved in the process of thermal expansion and contraction is reduced, which effectively solves the technical problems caused by the thermal expansion and contraction of the insulating filling material, and provides important methods and approaches for the independent research and development of ultra-high voltage DC optical fiber insulators.

[0040] In a specific embodiment, a plurality of silicone rubber outer umbrella skirts 5 are provided around the outer wall of the core rod 8. The plurality of silicone rubber outer umbrella skirts 5 are distributed along the axial direction of the core rod 8 to protect the core rod and the optical fiber insulator from environmental and climate influences.

[0041] In a specific embodiment, the optical fiber 6 includes a plurality of polarization-maintaining optical fibers, all of which are evenly spaced on the insulating support sheet 7 along the circumferential direction of the insulating support sheet 7, and each polarization-maintaining optical fiber is axially arranged in the optical fiber channel. More specifically, the optical fiber 6 includes 7 polarization-maintaining optical fibers, and the radial distribution radius of the 7 polarization-maintaining optical fibers is 4.5 mm. The 7 polarization-maintaining optical fibers are limited and fixed by the insulating support sheet 7 to avoid overlapping of the optical fibers to form a small gap, such as Figure 2 It is a schematic diagram of the relative position relationship between the optical fiber and the insulating support sheet in the glue-air composite optical fiber insulator; the material of the sheath is low smoke zero halogen material, that is, LSZH material. The full name of LSZH in English is Low Smoke Zero Halogen. LSZH material has excellent fire safety characteristics of low smoke, low toxicity and low corrosion.

[0042] In a specific embodiment, the resistivity of the insulating support sheet 7 is 1×10 14Ω·m, the radius of the insulating support sheet 7 is smaller than the inner diameter of the core rod 8, and the thickness is 2mm. More specifically, the number of insulating support sheets 7 is 6, and the insulating support sheets 7 are of a circular ring structure, all coaxially distributed with the core rod 8, and the radius of each sheet is slightly smaller than the inner diameter of the core rod 8, and the thickness is 2mm. The placement position is determined according to the electric field calculation optimization, wherein the electric field calculation optimization is determined by using the existing COMSOL finite element simulation technology, the English abbreviation is COMSOLCOMSOL Multiphysics, and a three-dimensional finite element simulation model of the optical fiber insulator is established by COMSOL finite element simulation technology, and the maximum field intensity information when the support sheet is placed at different heights is analyzed to determine the optimal placement position. In this embodiment, the distribution heights in the optical fiber insulator are 2500mm, 4600mm, 6700mm, 8800mm, 10900mm and 13000mm, respectively, and the material is polytetrafluoroethylene, and the resistivity is 1×10 14 Ω·m.

[0043] In a specific embodiment, Figure 4 Schematic diagram of the structure of the low-pressure end equalizing ring of the present invention. Figure 4 As shown, the outer wall of the low-voltage end fitting 1 of the optical fiber insulator 13 is detachably provided with a low-voltage end equalizing ring 2, the low-voltage end equalizing ring 2 is a single-ring structure, and the low-voltage end fitting 1 is a low-voltage end metal flange, wherein the low-voltage end equalizing ring 2 is detachably fixed to the outer wall of the low-voltage end fitting 1 by a plurality of first connecting rods, more specifically, there are two first connecting rods, which are fixed to the outer wall of the low-voltage end fitting 1 by first bolts, and can control the corona on the insulator, ensuring that the voltage is more evenly distributed on the optical fiber insulator 13, and this evenly distributed voltage helps to improve the stability and safety of the power system and reduce the risk of electrical failures caused by uneven voltage distribution. The ring diameter of the single-ring structure is 500mm, the tube diameter is 200mm, and the distribution height is 13287mm.

[0044] In a specific embodiment, Figure 3 This is a schematic diagram of the double ring structure of the high-pressure end equalizing ring of the present invention. Figure 3As shown, the outer wall of the high-voltage end fitting 3 of the optical fiber insulator 13 is detachably provided with a high-voltage end equalizing ring 4. The high-voltage end equalizing ring 4 is a double-ring structure, which can evenly distribute the high voltage around the object to ensure that there is no potential difference between the various parts of the ring, thereby achieving a voltage equalization effect. The high-pressure end fitting 3 is a high-pressure end metal flange, and the double-ring structure includes a first high-pressure end equalizing ring 11 and a second high-pressure end equalizing ring 12, wherein the first high-pressure end equalizing ring 11 is detachably arranged on the outer wall of the high-pressure end fitting 3, more specifically, it is fixed to the outer wall of the high-pressure end fitting 3 by bolts, and the second high-pressure end equalizing ring 12 is arranged on the outer periphery of the first high-pressure end equalizing ring 11, and is detachably fixed to the outer wall of the high-pressure end fitting 3 by multiple second connecting rods, more specifically, there are four second connecting rods, which are fixed to the outer wall of the high-pressure end fitting 3 by second bolts, wherein the ring diameter of the first high-pressure end equalizing ring 11 is 100mm, the pipe diameter is 40mm, and the distribution height is 325mm, and the ring diameter of the second high-pressure end equalizing ring 12 is 700mm, the pipe diameter is 300mm, and the distribution height is 400mm.

[0045] In summary, the present invention provides a novel fiber optic insulator structure of glue-gas composite for UHV DC FOCT, wherein the insulating filling material is filled in the high-voltage end part, and the rest is insulated with gas and the optical fiber is fixed by a support sheet. This scheme can not only improve the breakdown field strength of the equipment, but also effectively make the electric field inside the power equipment uniform, so that the maximum field strength of each key part can be effectively controlled, and the problem of local high field strength at the high-voltage end of the fiber optic insulator is effectively solved. The pouring height of the insulating filling material is relatively low, and the corresponding volume change after thermal expansion is also relatively small, and there is no need to reserve thermal expansion space for it. Compared with the technical scheme of traditional fiber optic insulators that mostly use the insulating filling material to fill the entire epoxy core, the dimensional margin is larger, and the probability of gas being involved in the thermal expansion and contraction process is reduced, which effectively solves the technical problems caused by the thermal expansion and contraction of the insulating filling material, and provides an important method and approach for the independent research and development of UHV DC fiber optic insulators.

[0046] It should be noted that when the present invention involves a numerical range, it should be understood that the two endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods used are the same as those in the embodiments, in order to avoid redundancy, the present invention describes a preferred embodiment. Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the attached claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0047] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A glue-air composite optical fiber insulator for ultra-high voltage direct current FOCT, comprising a core rod (8), characterized in that: The two ends of the core rod (8) are respectively sleeved with a low-voltage end fitting (1) and a high-voltage end fitting (3); the interior of the core rod (8) is a rubber-air composite insulation structure, wherein an insulating filling rubber layer (10) is provided in the core rod (8) located at the high-voltage end fitting (3), and the height of the insulating filling rubber layer (10) is greater than the height of the high-voltage end fitting (3). 13 Ω·m<the resistivity of the insulating filling glue layer (10)<10 14 Ω·m, used to control the local high field strength near the high voltage end; the rest of the core rod (8) is filled with a gas insulation layer (9); The core rod (8) is provided with an optical fiber channel axially therethrough, and an optical fiber (6) is provided through the optical fiber channel; A plurality of insulating support sheets (7) are provided in the axial direction of the optical fiber channel and in the optical fiber channel, and are used to limit and fix the optical fiber (6); The insulating filling adhesive layer (10) is an organic silicon gel layer. -4 / ℃<Thermal expansion coefficient of silicone gel layer<10 -3 / ℃, -5gf·s / m 2 <Adhesion of silicone gel layer<-4gf·s / m 2 ; The height of the insulating filling rubber layer (10) is 50 mm to 80 mm greater than the height of the high-voltage end fitting (3).

2. The glue-air composite optical fiber insulator for UHV DC FOCT according to claim 1, characterized in that: The optical fiber (6) comprises a plurality of polarization-maintaining optical fibers, all of which are distributed on the insulating support sheet (7) at equal intervals along the circumferential direction of the insulating support sheet (7), each polarization-maintaining optical fiber is axially arranged in the optical fiber channel, and each polarization-maintaining optical fiber is provided with a sheath.

3. The glue-air composite optical fiber insulator for UHV DC FOCT according to claim 1, characterized in that: The resistivity of the insulating support sheet (7) is 1×10 14 Ω·m, the radius of the insulating support sheet (7) is smaller than the inner diameter of the core rod (8), and the thickness is 2 mm.

4. The glue-air composite optical fiber insulator for UHV DC FOCT according to claim 1, characterized in that: The outer wall of the low-pressure end fitting (1) is provided with a low-pressure end equalizing ring (2), and the low-pressure end equalizing ring (2) is a single-ring structure.

5. The glue-air composite optical fiber insulator for UHV DC FOCT according to claim 1, characterized in that: The outer wall of the high-pressure end fitting (3) is provided with a high-pressure end equalizing ring (4), and the high-pressure end equalizing ring (4) is a double-ring structure.

6. The glue-air composite optical fiber insulator for UHV DC FOCT according to claim 1, characterized in that: The DC transmission of the UHV DC FOCT with glue-air composite optical fiber insulator is ±800kV.

7. The glue-air composite optical fiber insulator for UHV DC FOCT according to claim 1, characterized in that: The material used to prepare the core rod (8) is epoxy glass fiber composite material.

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