Strain insulator string for 1000kV extra-high voltage transformer substation suitable for high altitude

Abstract

The invention relates to a strain insulator string for a 1000kV extra-high voltage transformer substation suitable for a high altitude, and belongs to the technical field of insulator strings. Comprising an insulator assembly. The high-voltage side connecting fitting assembly is arranged at the lower end of the insulator assembly and is used for connecting a high-voltage wire; the grading ring is arranged at the joint of the lower end of the insulator assembly and the high-voltage side connecting fitting assembly, the grading ring is of a double-ring structure formed by coaxially arranging a large ring and a small ring, and the grading ring is located below the insulator assembly; and the shielding ring assembly is arranged below the grading ring and is connected to the high-voltage side connection fitting assembly, and the shielding ring assembly comprises two shielding rings which are symmetrically arranged on the two sides of the high-voltage side connection fitting assembly. The air gap discharge performance and the creeping discharge performance near the connection point are improved, the influence that the corona inception voltage is reduced due to elevation rise is counteracted, and therefore corona and noise are avoided.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of insulator string and specifically relates to a strain insulator string suitable for 1000kV extra-high voltage substation at high altitude. BACKGROUND

[0002] The air relative density is closely related to the withstand voltage level of the strain insulator string, the air relative density is lower in high altitude area, the creepage distance of the insulator string needs to be corrected to ensure that the insulator string is not broken down, the in-station conductor of the 1000kV extra-high voltage substation at 3000m-4000m altitude is corrected from 4 JLHN58K-1600 conductors to 6 JLHN58K-1600 conductors, which leads to the increase of the cross-line tension of the in-station, and the strain insulator string also needs to meet the related requirements of the tension.

[0003] With the increase of the altitude, the corona inception voltage on the surface of the fitting also decreases, the corona phenomenon is more likely to occur, and the electromagnetic environment problem of the high-voltage transmission line caused thereby is more serious, the occurrence of the corona not only increases the active loss of the substation, but also interferes with the surrounding radio communication, and the long-term continuous corona also ionizes the air to pollute the environment with ozone and nitrogen oxides. The type of the 1000kV strain insulator string of the conventional 1000kV substation is only suitable for low altitude areas. With the increase of the altitude, the corona, noise and radio interference of the insulator string are more and more intense, and a new type of grading ring and shielding ring needs to be used to meet the requirements of the corona, noise and radio interference of the strain insulator string for the 1000kV extra-high voltage substation at 3000m-4000m altitude. SUMMARY

[0004] To solve the above technical problems, the application provides a strain insulator string suitable for 1000kV extra-high voltage substation at high altitude.

[0005] To achieve the above purpose, the technical scheme adopted by the application is: The application provides a strain insulator string suitable for 1000kV extra-high voltage substation at high altitude, which comprises: An insulator assembly composed of two parallel insulator strings, the upper end of the insulator assembly is used for hanging on the side of the tower; A high-voltage side connecting fitting assembly arranged at the lower end of the insulator assembly and used for connecting the high-voltage conductor; A grading ring arranged at the connection between the lower end of the insulator assembly and the high-voltage side connecting fitting assembly, the grading ring is configured as a double-ring structure composed of a large ring and a small ring arranged coaxially, and the grading ring is located below the insulator assembly; A shielding ring assembly is arranged below the grading ring and connected to the high-voltage side connecting hardware assembly, and the shielding ring assembly comprises two shielding rings symmetrically arranged on both sides of the high-voltage side connecting hardware assembly.

[0006] Preferably, each insulator string in the insulator assembly is formed by 60 to 70 insulator pieces in series; the insulator pieces are selected to be bell-shaped insulator pieces, the height of a single insulator piece is 200mm to 210mm, the creepage distance is not less than 635mm, and the breaking load is not less than 420kN.

[0007] Preferably, the insulator assembly adopts a double-string parallel structure, and the center distance between the two insulator strings is set to be 600mm to 700mm.

[0008] Preferably, the large ring and the small ring of the grading ring are both in an elliptical structure. The large ring is made of aluminum alloy pipe material, the pipe diameter is 210mm to 230mm, the ring height is 2200mm to 2300mm, and the ring width is 1600mm to 1650mm. The small ring is made of aluminum alloy pipe material, the pipe diameter is 190mm to 210mm, the ring height is 1800mm to 1900mm, and the ring width is 1300mm to 1350mm.

[0009] Preferably, each shielding ring in the shielding ring assembly is configured in a racetrack structure and is made of aluminum alloy pipe material. The pipe diameter of the shielding ring is 210mm to 230mm, and the ring height is 1350mm to 1450mm. The length of the straight line segment of the racetrack structure is 1100mm to 1200mm, and the turning radius at the corner is 550mm to 650mm.

[0010] Preferably, the high-voltage side connecting hardware assembly comprises a connecting plate and a support plate, and the two shielding rings of the shielding ring assembly are symmetrically fixed to both sides of the connecting plate through the support plate, so that the two shielding rings spatially surround the high-voltage side connecting hardware assembly and the outgoing end of the high-voltage conductor.

[0011] Preferably, the high-voltage side connecting hardware assembly is provided with a strain clamp, the strain clamp is configured in a connection form suitable for 6-split conductors, and the breaking load of the hardware component bearing tension in the high-voltage side connecting hardware assembly is configured to be 420kN or 840kN.

[0012] Preferably, the plane where the large ring of the grading ring is located is at the gap between the first insulator piece and the second insulator piece at the lowermost end of the insulator assembly, and the plane where the small ring of the grading ring is located is at the gap between the second insulator piece and the third insulator piece at the lowermost end of the insulator assembly.

[0013] Preferably, the upper end of the insulator subassembly is connected to the tower side through a grounding side hardware assembly, which comprises, in sequence, a U-shaped hanging ring, a triangular connecting plate, a basket screw and a ball head hanging ring; the basket screw is used to adjust the length balance of the two parallel insulator strings.

[0014] Preferably, the high-voltage side hardware assembly further comprises an extension pull rod and a right-angle hanging plate; the upper end of the connecting plate is connected to the insulator string, the lower end of the connecting plate is connected to the extension pull rod, and the support plate of the shielding ring is fixedly connected to the side surface of the connecting plate through a bolt, so that the shielding ring is cantilevered on the radial outer side of the axis of the insulator string.

[0015] The application provides a 1000kV extra-high voltage substation tension insulator string suitable for high altitudes, and the beneficial effects of the application are embodied in: The requirement for correction of the creepage distance can ensure that the insulator string at an altitude of 3000m-4000m is not punctured, can greatly reduce the influence of the decrease of the corona onset voltage caused by the increase of the altitude, can effectively adjust the electric field of the connection point and the vicinity thereof, can improve the performance of the air gap discharge and the surface discharge in the vicinity of the connection point, can offset the influence of the decrease of the corona onset voltage caused by the increase of the altitude, and thus can avoid the generation of corona and noise. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 The figure is a front view of the 1000kV extra-high voltage substation tension insulator string suitable for high altitudes provided by the application; Figure 2 The figure is a side view of the 1000kV extra-high voltage substation tension insulator string suitable for high altitudes provided by the application; Figure 3 The figure is a front view of the shielding ring assembly of the 1000kV extra-high voltage substation tension insulator string suitable for high altitudes provided by the application; Figure 4 The figure is a field strength diagram of the grading ring in the 1000kV extra-high voltage substation tension insulator string suitable for high altitudes provided by the application; Figure 5 The figure is a field strength diagram of the shielding ring assembly in the 1000kV extra-high voltage substation tension insulator string suitable for high altitudes provided by the application; Figure 6 The figure is a potential distribution curve of the 1000kV extra-high voltage substation tension insulator string suitable for high altitudes provided by the application.

[0017] MARKS IN THE DRAWINGS: 1, insulator subassembly; 2, grading ring; 3, shielding ring assembly; 4, connecting plate; 5, support plate; 6, tension clamp; 7, extension pull rod; 8, right-angle hanging plate. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of protection of the present application.

[0019] Please refer to Figures 1-6 The specific embodiments provided by the present application are as follows: As Figures 1 to 3 As shown in the figure, the embodiment of the present application provides a strain insulator string suitable for 1000kV extra-high voltage substation at high altitude. The strain insulator string is usually suspended and installed in a vertical state in actual application, and the overall structure is mainly composed of an insulator assembly 1, a high-voltage side connecting hardware assembly, a grading ring 2 and a shielding ring assembly 3.

[0020] Among them, the insulator assembly 1 is the main insulating and force-bearing component, which is composed of two parallel insulator strings in parallel. This double-parallel structure can effectively share the mechanical tension of the extra-high voltage conductor. In the vertical installation state, the upper end of the insulator assembly 1 serves as the grounding side, which is used to be suspended and fixed on the tower or framework node of the substation; the lower end of the insulator assembly 1 serves as the high-voltage side, which extends downward to connect the conductor.

[0021] A high-voltage side connecting hardware assembly is provided at the lower end of the insulator assembly 1. This assembly serves as the hub of mechanical connection, responsible for physically connecting the insulator assembly 1 with the high-voltage conductor below and transmitting the tension.

[0022] In order to improve the electric field distribution in the high-altitude environment, a grading ring 2 is provided at the connection area between the lower end of the insulator assembly 1 and the high-voltage side connecting hardware assembly. The grading ring 2 is constructed as a double-ring structure, specifically including a large ring and a small ring arranged coaxially, and the large ring is fixedly connected with the small ring. From the spatial position, the grading ring 2 is located below the insulator assembly 1, adjacent to the end of the insulator string, mainly playing the role of improving the voltage distribution at the bottom of the insulator string.

[0023] Further, a shielding ring assembly 3 is provided below the grading ring 2. The shielding ring assembly 3 is connected to the high-voltage side connecting hardware assembly and includes two independent shielding rings. The two shielding rings are symmetrically arranged on both sides of the high-voltage side connecting hardware assembly, located below the grading ring 2. So that the shielding ring assembly 3 can form a spatial shielding protection for the high-voltage side connecting hardware assembly, effectively suppressing the corona discharge and radio interference caused by the complex shape of the hardware, thereby meeting the environmental protection and insulation requirements of the extra-high voltage substation in high-altitude areas.

[0024] In a preferred embodiment, in order to meet the requirements of insulation correction and mechanical load in high altitude environment, each string of insulators in the insulator subassembly 1 is composed of 60 to 70 pieces of insulator in series to ensure sufficient dry arc distance and insulation strength. In the specific selection of insulator, bell-shaped insulator is selected, which is beneficial to maintain good insulation performance in the environment of dirt and moisture. In terms of specific parameters, the height of a single insulator is controlled between 200mm to 210mm (preferably 205mm), and the creepage distance of a single insulator is designed to be not less than 635mm to provide sufficient creepage ratio distance; at the same time, considering that the strain string needs to bear a large tension of the conductor (such as the tension of 6 split conductors), the breaking load of a single insulator is set to be not less than 420kN, so as to ensure that the overall mechanical safety margin of the double string in parallel meets the specification requirements.

[0025] In a preferred embodiment, the insulator subassembly 1 adopts a double string parallel structure to meet the requirement of high mechanical strength of the incoming line interval of the ultra-high voltage substation, and to ensure that it can bear the huge tension conducted by the 6 split conductors. In this structure, in order to ensure the stability of the two strings of insulators in operation and prevent mutual interference, the center distance of the two strings of insulators is set to be 600mm to 700mm. This distance range (specifically 650mm in the preferred embodiment) is determined based on the size matching of the fittings and the requirements of wind deflection collision, which can ensure that the double string of insulators does not collide with each other under the action of strong wind or short circuit electric force, and can cooperate with the size of the upper and lower end connecting plate 4 to ensure that the two strings of insulators are balanced in force and maintain good mechanical and electrical properties.

[0026] In a preferred embodiment, in order to adapt to the spatial geometry after the parallel connection of the double string of insulators and optimize the electric field distribution in high altitude, the large ring and the small ring of the grading ring 2 are both in the shape of an ellipse. The long axis direction of this elliptical structure is consistent with the arrangement direction of the double string of insulators, which can effectively cover the high field strength area at the end of the insulator string. In terms of material selection, the large ring and the small ring are both preferably made of aluminum alloy pipe to balance the electrical conductivity and structural lightweight.

[0027] Specifically, in order to control the field strength of the outermost side of the high voltage end, the large ring adopts a larger pipe diameter, which is set to be 210mm to 230mm (preferably 220mm), and in terms of overall size, the ring height is set to be 2200mm to 2300mm (preferably 2250mm), and the ring width is set to be 1600mm to 1650mm (preferably 1620mm).

[0028] The small ring used in cooperation with the large ring is also made of aluminum alloy pipe material, with a pipe diameter range of 190mm to 210mm (preferably 200mm), and an overall size of a ring height of 1800mm to 1900mm (preferably 1850mm) and a ring width of 1300mm to 1350mm (preferably 1320mm).

[0029] By using the rough pipe diameter aluminum pipe in the specific range, the curvature radius of the grading ring 2 is significantly increased, so as to effectively control the electric field intensity on the surface of the grading ring 2 below the allowable value (such as 1.30kV / mm), avoiding serious corona discharge and noise in the high-altitude low-pressure environment.

[0030] In a preferred embodiment, each shielding ring in the shielding ring assembly 3 is configured as a racetrack-shaped structure (i.e., an oblong circle) and is made of aluminum alloy pipe material with good electrical conductivity and light weight, in view of the structural features of the high-voltage side connecting hardware assembly and the need for high-altitude anti-corona. Compared with the traditional circular structure, the racetrack-shaped structure can better adapt to the wide hardware connection area at the lower end of the double-string insulator and provide more conformable shielding protection.

[0031] In order to ensure that the surface field intensity of the shielding ring meets the control index (controlled within 1.30kV / mm) in the high-altitude environment, the shielding ring adopts a large pipe diameter, with a pipe diameter range of 210mm to 230mm (220mm in the preferred embodiment). In terms of overall profile size, the ring height (i.e., the total length in the long axis direction) of the shielding ring is set to 1350mm to 1450mm (1400mm in the preferred embodiment). Among them, in order to form effective shielding for the lower strip-shaped connecting plate 4 and the connecting hardware, the length of the straight section of the racetrack-shaped structure is set to 1100mm to 1200mm (1150mm in the preferred embodiment); at the same time, in order to smooth the electric field distortion at the corner and prevent local corona due to too small curvature radius, the corner radius is set to 550mm to 650mm (600mm in the preferred embodiment).

[0032] In a preferred embodiment, in order to effectively electrically shield the complex hardware structure at the high-voltage end, the high-voltage side connecting hardware assembly includes a connecting plate 4 for bearing force and a support plate 5 specially used for mounting the shielding ring. Specifically, the shielding ring assembly 3 includes two independent racetrack-shaped shielding rings, which are symmetrically fixed on the two sides of the connecting plate 4 through the support plate 5.

[0033] Based on this, two shielding rings are respectively located on the left and right (or front and back) outer sides of the connecting hardware assembly, and the high-voltage side connecting hardware assembly (including the connecting plate 4, the hanging plate, the pin shaft, etc.) and the outgoing end of the high-voltage conductor (i.e. the outlet of the strain clamp 6) at a high potential are tightly surrounded in the equipotential area inside the shielding ring. Through this spatial surrounding structure, the electric field on the surface of the hardware can be effectively homogenized, and the local electric field distortion caused by the edges of the connecting plate 4, bolts or pins, etc. can be eliminated, thereby preventing corona discharge and protecting the hardware from arc ablation.

[0034] In a preferred embodiment, in order to cope with the huge mechanical tension brought by the multi-bundle large cross-section conductor of the extra-high voltage transmission line in high-altitude areas, the high-voltage side connecting hardware assembly is configured with a strain clamp 6. The strain clamp 6 is configured to be suitable for the connection form of 6-bundle conductors (for example, JLHN58K-1600 type conductors), and through the shunt connection of the connecting plate 4 and the extended tension rod 7, stable clamping and electrical lead-out of the 6 sub-conductors are realized.

[0035] In the mechanical strength design, considering the severe weather conditions such as heavy icing and strong wind that the 3000m-4000m high-altitude area may face, as well as the significant tension superposition effect of 6-bundle conductors, the hardware components of the high-voltage side connecting hardware assembly that bear tension at all levels are configured with high-grade mechanical configuration. According to the position and stress state of each hardware in the stress transmission path, the breaking load is configured to be 420kN or 840kN. For example, at the main node or key tension connecting plate 4 where the double-string insulators converge, hardware with a breaking load of 840kN can be preferred to ensure sufficient safety margin; while at the shunt connection points of each branch or the hardware connected to a single sub-conductor, hardware with a breaking load of 420kN can be configured. This differentiated strength configuration not only ensures the mechanical safety of the insulator string as a whole under extreme tension, preventing hardware failure, but also realizes the economy and weight optimization of the hardware combination.

[0036] In a preferred embodiment, in order to regulate the potential distribution at the high-voltage end of the insulator string and prevent corona discharge caused by high voltage gradient, the plane where the large ring of the voltage equalizing ring 2 is located is configured to be at the gap between the 1st insulator sheet and the 2nd insulator sheet at the lowermost end (i.e. the high-voltage side end) of the insulator assembly 1; at the same time, the plane where the small ring of the voltage equalizing ring 2 is located is configured to be at the gap between the 2nd insulator sheet and the 3rd insulator sheet at the lowermost end of the insulator assembly 1. This specific installation position can maximize the improvement of the voltage bearing proportion of the first few insulator sheets at the high-voltage end, effectively shield the strong electric field at the high potential, avoid the occurrence of surface flashover due to excessive field strength, and ensure the safe operation of the insulator string in the 3000m-4000m high-altitude environment.

[0037] In a preferred embodiment, in order to realize reliable mechanical connection between the insulator subassembly 1 and the tower side and ensure force balance of the double-string parallel structure, the upper end of the insulator subassembly 1 is hung on the tower hanging point through a grounding side hardware assembly. The grounding side hardware assembly sequentially includes a U-shaped hanging ring, a triangular connecting plate 4, a basket screw and a ball head hanging ring in the connection path.

[0038] Specifically, the U-shaped hanging ring is located at the uppermost end and is used for being directly hung on the hanging point hardware of the tower; the lower part of the U-shaped hanging ring is connected to the top vertex hole of the triangular connecting plate 4. The basket screw for adjustment is connected at the two connecting holes at the bottom of the triangular connecting plate 4; the lower end of the basket screw is connected to the ball socket hardware at the top of each string of insulator strings through the ball head hanging ring. In this configuration, the effective length of the two strings of parallel insulator strings can be accurately fine-tuned by rotating to adjust the extension amount of the screw rod, so as to eliminate the length inconsistency caused by manufacturing tolerances or installation errors, ensure that the two strings of insulator strings can bear the conductor load synchronously and keep the tension balance, and prevent the single string of insulator from being overloaded due to uneven force.

[0039] In a preferred embodiment, in order to build a stable mechanical force transmission channel and realize lateral support of the shielding ring, the high-voltage side connecting hardware assembly further includes an extended pull rod 7 and a right-angle hanging plate 8 in structural details. In the main force path, the connecting plate 4 (for example, the LT4-50J or L-25J type connecting plate 4) serves as a core connecting node: the upper end thereof is connected to the bottom ball socket of the insulator string through the ball head hanging ring or the right-angle hanging plate 8, and the lower end thereof is connected to the extended pull rod 7 through the right-angle hanging plate 8, and then extended to the strain clamp 6.

[0040] On the basis of the mechanical connection, the support plate 5 (for example, the ZCP type support plate 5) of the shielding ring is fastened and connected to the side surface (i.e., the non-main force plane) of the connecting plate 4 through a high-strength bolt assembly. This connection mode makes the entire racetrack type shielding ring be arranged in a cantilevered manner on the radial outside of the axis of the insulator string, so as to position the shielding ring at the optimal electric field shielding position without interfering with the mechanical properties of the central main force hardware (connecting plate 4, pull rod, etc.), and ensure that the shielding ring can form effective Faraday cage protection for the internal connecting hardware.

[0041] The application also provides a specific application embodiment, and the specific application scene is the incoming line interval of a main transformer of a substation.

[0042] The incoming line interval adopts 6 split JLHN58K-1600 type wires. According to the incoming line length of 57 m, the maximum working tension borne by the insulator string is 129 kN. According to relevant UHV design standards, the safety margin is 5.3 times, and the breaking load requirement of the insulator string is at least 129 kN x 5.3 = 683.7 kN. Therefore, the double-string parallel scheme is adopted in the embodiment, and the single-string insulator is selected to be a product with a breaking load of 420 kN, and the total breaking load after parallel connection of the double strings reaches 840 kN, meeting the mechanical safety requirements.

[0043] Based on the above load and anti-flashover requirements, the insulator sheet type U420BP / 205T (bell type) is selected. The main parameters of a single sheet are: structure height 205 mm, creepage distance 635 mm, and rated mechanical breaking load 420 kN.

[0044] Insulator sheet number calculation and verification: In order to determine the minimum number of sheets (64) required for a single string of insulators, the following multi-dimensional correction calculation and verification are performed: Creepage ratio method calculation: According to DL / T-5222 "Technical Regulation for Selection and Design of Conductors and Electrical Apparatus", combined with the creepage distance parameters of U420BP / 205T, and considering the 4000 m altitude correction coefficient and appropriate margin, the reference number of sheets is calculated to be 64.

[0045] Pollution withstand voltage method verification: The environmental conditions are set to 4000 m altitude and d level pollution. Using the pollution withstand voltage method, the recommended number of sheets for the V string insulator is 58, and the 64 selected in the embodiment meets the requirement.

[0046] Comparison and verification with the line side: Referring to the design of the line insulator string on the outgoing side of the substation (XSP2-300 type, creepage distance 550 mm, total 71 sheets), it is converted into insulator sheets with a creepage distance of 635 mm, which is equivalent to 61.5 sheets. The 64 selected in the embodiment is higher than this value, meeting the principle that the station internal insulation level is not lower than that of the outgoing side.

[0047] Minimum safety clearance verification: The specification requires that the minimum safety clearance of the 1000 kV grading ring to the ground at 1000 m altitude is 7.5 m. After high altitude correction calculation, the clearance at 4000 m altitude needs to be considered as 9.2 m. After verification, the dry arc distance and the gap to the ground of the insulator string assembled by 64 U420BP / 205T insulator sheets can meet the above A1 value (9.2 m) requirement.

[0048] In summary, the number of insulator sheets in a single string in the embodiment is determined to be 64, and the total creepage distance of the double-string parallel connection meets the application requirements at 4000 m altitude.

[0049] In view of the problem that the decrease of air density in high-altitude areas leads to the decrease of corona inception voltage, the embodiment proposes a differentiated surface field strength control strategy: the surface field strength control value Ec1 of the grading ring and the shielding ring of the transformer substation insulator string is set to 1.30 kV / mm; for the fitting area with extremely high field strength in individual positions and difficult to control by conventional means, the surface field strength allowable value Ec2 is relaxed to 1.50 kV / mm.

[0050] In order to meet the above indicators, the embodiment carries out electric field calculation and analysis on pipe materials with different pipe diameters (75 mm, 150 mm, 180 mm, 200 mm, 220 mm, and 260 mm) through finite element modeling simulation, and finally determines the following design scheme: As shown in Figure 5 , the simulation results show that when the shielding ring adopts an aluminum alloy pipe with a pipe diameter of 220 mm, the maximum surface field strength is about 1.32 kV / mm. This value is slightly higher than 1.30 kV / mm but far below the limit value of 1.50 kV / mm, which can effectively shield the connection fittings with complex internal shapes and prevent sharp tip discharge. As shown in the figure, the high field strength area on the surface of the shielding ring is mainly concentrated in the circular arc corner of the racetrack ring. By adopting a large turning radius of R600 mm in combination with a pipe diameter of 220 mm, the electric field distribution at this place is effectively improved.

[0051] As shown in Figure 4 , the simulation results show that when the grading ring adopts a double-ring structure (large ring pipe diameter 220 mm / small ring pipe diameter 200 mm), the maximum surface field strength is about 1.29 kV / mm. This value is successfully controlled within the preferred index of 1.30 kV / mm. As shown in the figure, the high field strength area of the double-ring structure is mainly distributed on the outer surface of the ring body, and the double-ring voltage division effect significantly reduces the potential gradient on the surface of the single ring.

[0052] In order to verify the rationality of the installation position of the grading ring, the potential distribution of the entire insulator string is calculated. As shown in the Figure 6 insulator string voltage distribution curve (U-shaped curve), the insulator sheet near the high-voltage end bears the highest voltage. According to the potential distribution curve, the best axial installation position of the grading ring is determined in this embodiment: the plane where the large grading ring is located is adjusted to be between the 1st and 2nd insulator sheets; the plane where the small grading ring is located is adjusted to be between the 2nd and 3rd insulator sheets.

[0053] Through this deep insertion type installation method, the grading ring can form a strong shielding effect on the first few insulator sheets at the high-voltage end. As can be seen from the voltage distribution graph, after the grading correction, the maximum voltage (about 26.5 kV) borne by a single insulator sheet appears near the 5th-6th insulator sheet, and the voltage at the end (1st insulator sheet) is successfully suppressed below 20 kV, effectively avoiding the risk of arc ablation and flashover at the bottom of the insulator, and ensuring the electrical safety in high-altitude environments.

[0054] While embodiments of the application have been shown and described, it is to be understood that the embodiments described are merely exemplary of the principles and application of the present application. Numerous modifications and adaptions can be effected without departing from the spirit and scope of the present application, which is not limited to the exact construction described. Accordingly, the scope of the present application is not intended to be limited to the specific embodiments disclosed.

Claims

1. A tension insulator string suitable for 1000kV UHV substations at high altitudes, characterized in that, include: An insulator assembly consists of two strings of insulators connected in parallel, with the upper end of the insulator assembly used for suspension on the side of the tower. A high-voltage side connecting hardware assembly is located at the lower end of the insulator assembly and is used to connect the high-voltage conductor; An equalizing ring is disposed at the lower end of the insulator assembly and at the connection point between it and the high-voltage side connecting hardware assembly. The equalizing ring is constructed as a double-ring structure consisting of a large ring and a small ring arranged coaxially, and the equalizing ring is located below the insulator assembly. A shielding ring assembly is disposed below the equalizing ring and connected to the high-voltage side connection hardware assembly. The shielding ring assembly includes two shielding rings symmetrically arranged on both sides of the high-voltage side connection hardware assembly.

2. The tension insulator string for 1000kV UHV substations at high altitudes as described in claim 1, characterized in that, Each insulator string in the insulator assembly consists of 60 to 70 insulator discs connected in series; the insulator discs are bell-shaped insulator discs, with a single insulator disc height of 200mm to 210mm, a creepage distance of not less than 635mm, and a breaking load of not less than 420kN.

3. The tension insulator string for 1000kV UHV substations at high altitudes as described in claim 2, characterized in that, The insulator assembly adopts a double-string parallel structure, and the center-to-center distance between the two insulator strings is set to 600mm to 700mm.

4. The tension insulator string for 1000kV UHV substations at high altitudes as described in claim 1, characterized in that, Both the large and small rings of the equalizing ring are elliptical structures; The large ring is made of aluminum alloy tubing with a diameter of 210mm to 230mm, a ring height of 2200mm to 2300mm, and a ring width of 1600mm to 1650mm. The small ring is made of aluminum alloy tubing with a diameter of 190mm to 210mm, a ring height of 1800mm to 1900mm, and a ring width of 1300mm to 1350mm.

5. The tension insulator string for 1000kV UHV substations at high altitudes as described in claim 1, characterized in that, Each shielding ring in the shielding ring assembly is constructed as a racetrack-shaped structure and is made of aluminum alloy tubing. The diameter of the shielding ring is 210mm to 230mm, and the ring height is 1350mm to 1450mm; The straight section of the runway-shaped structure has a length of 1100mm to 1200mm, and the turning radius at the corner is 550mm to 650mm.

6. The tension insulator string for 1000kV UHV substations at high altitudes as described in claim 1, characterized in that, The high-voltage side connection hardware assembly includes a connecting plate and a support plate. The two shielding rings of the shielding ring assembly are symmetrically fixed to both sides of the connecting plate through the support plate, so that the two shielding rings spatially surround the high-voltage side connection hardware assembly and the lead-out end of the high-voltage wire.

7. The tension insulator string for 1000kV UHV substations at high altitudes as described in claim 6, characterized in that, The high-voltage side connection hardware assembly is equipped with a tension clamp, which is constructed to be suitable for the connection of 6-split conductors, and the breaking load of the hardware component bearing the tensile force in the high-voltage side connection hardware assembly is configured to be 420kN or 840kN.

8. The tension insulator string for 1000kV UHV substations at high altitudes as described in claim 7, characterized in that, The plane containing the large ring of the equalizing ring is located in the gap between the first and second insulator discs at the bottom of the insulator assembly, and the plane containing the small ring of the equalizing ring is located in the gap between the second and third insulator discs at the bottom of the insulator assembly.

9. The tension insulator string for 1000kV UHV substations at high altitudes as described in claim 8, characterized in that, The upper end of the insulator assembly is connected to the tower side via a grounding-side hardware assembly, which includes, in sequence, a U-shaped hanging ring, a triangular connecting plate, a turnbuckle, and a ball-head hanging ring; the turnbuckle is used to adjust the length balance of the two parallel insulator strings.

10. The tension insulator string for 1000kV UHV substations at high altitudes according to claim 9, characterized in that, The high-voltage side connection hardware assembly also includes an extension rod and a right-angle hanging plate; the upper end of the connecting plate is connected to the insulator string, the lower end of the connecting plate is connected to the extension rod, and the support plate of the shielding ring is fixedly connected to the side of the connecting plate by bolts, so that the shielding ring is cantilevered on the radially outer side of the axis of the insulator string.

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