A design method of composite insulator shed for different ice regions and cooperating with thermal jet deicing

Abstract

This invention discloses a composite insulator skirt design method that adapts to different icing zones and coordinates with hot water jet de-icing, relating to the field of transmission line insulator technology. Addressing the problems of fixed umbrella shape parameters, poor adaptability to different icing zones, and susceptibility to ice flashover caused by icing bridging in existing composite insulators, this invention employs a modular, graded, and adjustable umbrella skirt assembly in its main composite insulator structure. Differentiated umbrella diameter, tilt angle, and spacing parameters adapt to the icing characteristics of light, medium, and heavy icing zones, while simultaneously coupling and adapting with the parameters of hot water jet de-icing technology. This invention achieves coordinated icing suppression and hot water jet de-icing in different icing zones, delaying icing bridging, increasing ice flashover field strength, and reducing operation and maintenance costs through modular design, ensuring the safe and stable operation of transmission lines in icing areas.

Description

Technical Field

[0001] This invention relates to the field of pollution and icing of transmission lines, specifically a composite insulator skirt design method that adapts to different icing zones and works in conjunction with thermal jet de-icing. Background Technology

[0002] Compared to traditional porcelain and glass insulator strings, composite insulators are increasingly widely used in high-voltage transmission systems due to their advantages such as light weight, high strength, excellent pollution resistance, and convenient operation and maintenance. In heavily polluted areas, their use can also significantly reduce the size of ultra-high-voltage / extra-high-voltage transmission towers and lower the construction cost of transmission systems. However, in icing environments, both artificial simulation tests and field operating experience show that the ice flashover characteristics of existing composite insulator structures are not significantly better than those of porcelain and glass insulators. Furthermore, existing umbrella-shaped structures are not specifically designed for hot water jet de-icing, resulting in low jet de-icing efficiency and poor compatibility with the umbrella shape, failing to achieve synergy between anti-icing and active de-icing.

[0003] Therefore, this study on the umbrella-shaped structure of composite insulators under icing conditions, combining icing tests and ice flashover theory, and proposing specific umbrella-shaped optimization design criteria, has important theoretical significance and practical engineering value for improving the electrical performance of composite insulators in icing areas, enhancing the efficiency of thermal jet de-icing, and reducing icing disasters in power grids. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a composite insulator skirt design method that is adaptable to different ice zones and synergistic with hot jet de-icing. Based on the key umbrella shape characteristics that affect the flashover voltage of the ice-covered composite insulator, and combined with the core characteristics of hot water jet de-icing such as heat conduction, impact force transmission, and jet conduction, the umbrella shape parameter law with excellent ice flash characteristics is obtained. Based on this law and combined with the requirements of umbrella shape design in polluted areas, the composite insulator umbrella structure for three different ice zones is optimized.

[0005] Therefore, the present invention adopts the following technical solution: a composite insulator skirt design method applicable to different ice zones. The main structure of the composite insulator adopts a graded adjustable modular skirt assembly, which adapts to the icing characteristics of light ice zone, medium ice zone and heavy ice zone through differentiated umbrella diameter, tilt angle and spacing parameters, and is coupled and adapted with the parameters of hot water jet de-icing technology. The main structure of the composite insulator meets the following pollution zone design requirements: The creepage distance of composite insulators should be 0.75 to 1 times that of porcelain insulators in the same pollution area. The icing coefficient CF is less than 3.2 in pollution zones I and II, and less than 3.8 in pollution zones III and IV; The spacing between adjacent umbrella skirts is greater than 30mm, the difference in umbrella diameter for umbrella structures with unequal diameters is not less than 30mm, the ratio of the radial extension of the insulator skirt to the axial spacing matching characteristic k2 is not less than 0.8, and the ratio of the maximum skirt diameter to the insulator core rod diameter k3 does not exceed 5.0. The upper surface of the umbrella skirt has an inclination angle of 10-16°, the lower surface has an inclination angle of 3-8°, and the rod diameter is uniformly 32-36mm to adapt to the heat conduction and impact force transmission of hot water jets.

[0006] The optimization design of this invention is mainly based on improving the flashover voltage of composite insulators and meeting the basic requirements of umbrella-shaped design in polluted areas.

[0007] Preferably, the ice zone classification criteria are as follows: ice thickness d < 10 mm is light ice zone, 10 mm ≤ d < 20 mm is medium ice zone, and d ≥ 20 mm is heavy ice zone.

[0008] Preferably, the umbrella-shaped structure of the graded adjustable modular umbrella skirt assembly and the hot water jet parameters satisfy the following coupling relationship: the umbrella skirt spacing matches the jet diffusion angle, the umbrella surface tilt angle is at an angle of 15~30° with the jet impact angle, and the umbrella diameter difference is adapted to the kinetic energy distribution in the core area of ​​the jet, ensuring that the jet has no energy blind zone in the umbrella skirt shielding area, while avoiding the risk of surface discharge caused by the jet.

[0009] The hot water jet achieves synergistic optimization of icing suppression, active de-icing, and fouling resistance by optimizing the umbrella-shaped flow field characteristics and the jet action path.

[0010] Preferably, the light icing zone is designed with an ice thickness of d=5mm as the baseline and d=10mm as the maximum ice thickness, and is optimized for conventional umbrella shapes. Specific parameters include: Umbrella spacing: determined by formula Calculate the critical umbrella spacing for the transition of ice tip arc discharge mode when ice coverage is 5mm. Through formula Calculate the critical umbrella spacing for icicle bridging when the icing is 10mm. The optimized maximum umbrella spacing d1=(d 1s-5 +d 1b-10 ) / 2; where D1 and D2 are the maximum and second largest skirt diameters, respectively; Umbrella diameter parameters: Based on the actual requirements of the light icing zone, the umbrella structure is designed with priority order of creepage coefficient, flashover critical field strength Ec, and k1 (the ratio of the difference between the maximum umbrella skirt extension p1 and the minimum umbrella skirt extension p2 to the maximum umbrella skirt extension p1) to determine D1, D2, and d; the composite insulator is designed differently, and the umbrella skirt repeating unit is designed as a "large umbrella skirt - medium umbrella skirt - small umbrella skirt - medium umbrella skirt - small umbrella skirt" structure, where the large umbrella skirt refers to the largest umbrella skirt, the small umbrella skirt refers to the smallest umbrella skirt, and the medium umbrella skirt refers to the umbrella skirt between the largest and smallest umbrella skirts; Jet adaptation characteristics: The inclination angle of the upper surface of the umbrella skirt and the differentiated umbrella diameter form a flow guiding channel, allowing the hot water jet (temperature 60-90℃, outlet pressure 0.5-1.5MPa) to uniformly cover the umbrella surface. Compared with the jet heat exchange effect of conventional umbrella insulators, the convective heat transfer coefficient between the jet and the ice layer is increased by more than 30%, achieving rapid melting and detachment of light ice.

[0011] Preferably, in the medium-ice zone, the ice thickness is based on d=15mm and the maximum ice thickness is d=20mm. The jet de-icing effect is enhanced by adding an extra-large umbrella skirt. Specific design includes: Extra-large umbrella parameters: maximum umbrella spacing d1=450mm, number of extra-large umbrellas N1=4, umbrella structure is designed with priority order of flashover critical field strength Ec, creepage coefficient, k1 (the ratio of the difference between the maximum umbrella skirt extension p1 and the minimum umbrella skirt extension p2 to the maximum umbrella skirt extension p1); at the same time, the maximum umbrella skirt diameter D1 and the second largest umbrella skirt diameter D2 are selected according to the level of contamination. Umbrella skirt combination method: Level III and IV contaminated areas adopt a quasi-"large umbrella skirt-small umbrella skirt" repeating unit, while Level I and II contaminated areas adopt a quasi-"large umbrella skirt-small umbrella skirt-medium umbrella skirt-small umbrella skirt" repeating unit; Jet-assisted design: The spacing between the oversized umbrella and the regular umbrella is adapted to the distribution of jet impact force. The hot water jet uses a conical nozzle with a spray distance controlled between 1.5 and 2.8 m. The water conductivity is ≤500 μS / cm and the leakage current does not exceed 1 mA. Through the synergistic effect of the jet impact force and the umbrella tilt angle, the middle layer of ice is cracked and detached.

[0012] More preferably, the umbrella diameter parameters for the medium ice zone are: D1=230mm and D2=140mm for Class III and IV contaminated areas, and D1=250mm and D2=150mm for Class I and II contaminated areas.

[0013] More preferably, the contraction angle of the conical nozzle is 30~50°.

[0014] Preferably, in the heavy icing zone, the ice thickness is based on d=30mm, and a double-diameter extra-large umbrella skirt is arranged in a cross pattern. The specific design includes: Extra-large umbrella configuration: Select extra-large umbrella skirts with diameters of 300mm and 230mm and install them in a cross pattern, with a spacing of 450mm between adjacent extra-large umbrellas, and match them with regular umbrella skirts of 150mm, 120mm and 90mm. Low wind speed adaptation: When the ambient wind speed is ≤3m / s, the first extra-large umbrella is replaced with a 150mm ordinary large umbrella to increase the ice layer resistance and the jet action area. Jet enhancement design: Adapted to high-pressure hot water jets (temperature 90-120℃, outlet pressure 1.5-3.0MPa), the jet penetrates to the root of the ice ridges along the umbrella-shaped flow channel. Utilizing the dual effects of heat conduction and impact force, the time for thick ice layers to detach is reduced by more than 50%.

[0015] Preferably, when using hot water jet adaptation, it also includes safety protection design: by optimizing the umbrella-shaped electric field distribution, the water column insulation distance during live work meets the preset standard (such as GB / T13395-2008 standard), the leakage current monitoring threshold is set to 1mA, and the spray distance is adjustable in the range of 5~15m.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. Compared with conventional composite insulators with the same umbrella spacing, the present invention has a smaller average umbrella extension, better pollution accumulation characteristics, and the pollution flashover voltage meets the requirements of Class III pollution area (161kV / m). 2. In this invention, the flashover voltage of the composite insulator in the icing zone and the heavy icing zone should be higher than that of their respective conventional insulators. The flashover voltage of the "large-small" umbrella insulator is higher, and the aerodynamic characteristics of the "large-small-medium-small" umbrella insulator are better. In the heavy icing zone, the super-large umbrella cross arrangement is adopted to delay the bridging of ice ridges and improve the reliability of insulation. 3. This invention extracts the key umbrella-shaped characteristic quantities that affect the flashover voltage of icing composite insulators, derives their influence laws, and combines them with the technical characteristics of hot water jet de-icing for coupling design, and based on this, performs differentiated and precise design of the ice zone of composite insulators. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a diagram showing the relationship between Ec and D1 and D2 when d=10mm in a specific embodiment of the present invention. Figure 2 This is a diagram showing the relationship between k1, D1, and D2 in a specific embodiment of the present invention; Figure 3 This is a diagram showing the relationship between the maximum CF coefficient and D1 and D2 in a specific embodiment of the present invention; Figure 4 This is a structural diagram of the umbrella-shaped composite insulator design for the present invention applicable to light icing zones; Figure 5This is a diagram showing the relationship between Ec and D1 and D2 when d=15 and 20mm in a specific embodiment of the present invention. Figure 6 This is a structural diagram of the umbrella-shaped composite insulator design for medium-icing zones with relatively light pollution, as per the present invention. Figure 7 This is a structural diagram of the umbrella-shaped composite insulator design for medium-icing areas with heavy pollution, as per the present invention. Figure 8 This is a structural diagram of the umbrella-shaped composite insulator design for the present invention, applicable to areas with relatively light pollution and heavy icing. Figure 9 This is a structural diagram of the umbrella-shaped composite insulator design for heavy icing areas where the wind speed is low, according to the present invention. Detailed Implementation

[0019] The technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0020] Improving the flashover voltage and ice flashover voltage of transmission lines to ensure power supply reliability is an urgent problem to be solved. Based on the influence of umbrella structure parameters on ice flashover voltage, and combined with the heat conduction, impact force transmission, and jet conduction characteristics of hot water jet de-icing, an optimized umbrella structure scheme for composite insulators suitable for icing areas is proposed to solve the applicability problem of composite insulators in icing areas. This embodiment provides three optimized umbrella structures for anti-icing composite insulators in different icing areas, which can reduce the occurrence of flashover accidents, improve the efficiency of hot water jet de-icing, and improve the reliability of power supply from transmission lines.

[0021] This embodiment presents a composite insulator skirt design method applicable to different ice zones. The composite insulator body adopts a graded adjustable modular skirt assembly, which adapts to the icing characteristics of light ice, medium ice and heavy ice zones through differentiated umbrella diameter, tilt angle and spacing parameters. At the same time, it is coupled and adapted with the parameters of hot water jet de-icing technology (i.e. matching the heat conduction, impact force transmission and jet flow characteristics of hot water jet de-icing).

[0022] The optimized umbrella-shaped structure of the anti-icing composite insulator of the present invention for different icing zones meets the requirements of umbrella-shaped design in polluted areas.

[0023] The creepage distance of composite insulators should be 0.75 to 1 times that of porcelain insulators in the same pollution area. The icing coefficient CF is less than 3.2 in pollution zones I and II, and less than 3.8 in pollution zones III and IV; The spacing between adjacent umbrella skirts is greater than 30mm, the difference in umbrella diameter for umbrella structures with unequal diameters is not less than 30mm, the ratio of the radial extension of the insulator skirt to the axial spacing matching characteristic k2 is not less than 0.8, and the ratio of the maximum skirt diameter to the insulator core rod diameter k3 does not exceed 5.0. The upper surface of the umbrella skirt has an inclination angle of 10-16°, the lower surface has an inclination angle of 3-8°, and the rod diameter is uniformly 32-36mm to adapt to the heat conduction and impact force transmission of hot water jets.

[0024] The different ice zones in this invention are classified according to ice thickness. The ice zone classification criteria are as follows: ice thickness d < 10 mm is light ice zone, 10 mm ≤ d < 20 mm is medium ice zone, and d ≥ 20 mm is heavy ice zone.

[0025] The umbrella-shaped structure of the graded adjustable modular umbrella skirt assembly and the hot water jet parameters satisfy the following coupling relationship: the umbrella skirt spacing matches the jet diffusion angle, the umbrella surface tilt angle forms an angle of 15~30° with the jet impact angle, and the umbrella diameter difference is adapted to the kinetic energy distribution in the core area of ​​the jet, ensuring that the jet has no energy blind zone in the umbrella skirt shielding area, while avoiding the risk of surface discharge caused by the jet. When using hot water jet adaptation, safety protection design is also included: by optimizing the umbrella-shaped electric field distribution, the water column insulation distance during live work meets the GB / T13395-2008 standard, the leakage current monitoring threshold is set to 1mA, and the spray distance is adjustable within the range of 5~15m.

[0026] The hot water jet achieves synergistic optimization of icing suppression, active de-icing, and fouling resistance by optimizing the umbrella-shaped flow field characteristics and the jet action path.

[0027] For the design of the umbrella-shaped structure of composite insulators in light icing zones, the ice thickness is based on an icing degree of d=5mm and a maximum ice thickness of d=10mm. Under these conditions, the ice flashover voltage Umf of insulators is relatively large for all types of insulators. Therefore, there is no need to improve their ice flashover characteristics by adding extra-large umbrella skirts. The umbrella shape design is mainly for conventional umbrella shapes.

[0028] Furthermore, determine the spacing between umbrellas in the light ice zone. :

[0029]

[0030]

[0031] In the formula, d is the ice thickness. The optimized maximum umbrella spacing is represented by D1 and D2, which are the maximum and second maximum umbrella skirt diameters, respectively. The critical umbrella spacing for the transition of ice tip arc discharge mode when the ice thickness is 5mm. The critical spacing between ice ridges for bridging when the ice thickness is 10mm.

[0032] Furthermore, obtain a reasonable combination of D1 and D2. This is based on D1, D2, and the above... The flashover critical field strength Ec value when d=10mm can be calculated. Then, based on the umbrella-shaped parameter requirements of the polluted area, without considering... The case where d ≤ 30mm. The calculated value of Ec when d = 10mm is as follows: Figure 1 As shown, the value ranges of D1 and D2 are as follows: Figure 1 The dashed box in the image is shown.

[0033] Furthermore, based on the actual requirements of the light icing zone, the umbrella structure is designed with CF coefficient, Ec, and k1 as the priority order to determine D1, D2, and d, i.e., according to... Figure 2 and Figure 3 The value of k1 is determined by the ratio of the difference between the maximum umbrella extension p1 and the minimum umbrella extension p2 to p1. Ultimately, a combination of D1=160mm, D2=110mm, and d1=154mm was chosen, at which point the composite insulator has relatively superior CF coefficient, ice flashover gradient, and k1.

[0034] The expressions and calculation diagrams for parameters k1, k2, and k3 are shown in Table 1 below.

[0035] Table 1. Definition of Umbrella Structure Parameters

[0036] In Table 1, l 1. The axial net spacing between the main umbrella skirts (large / extra-large umbrella skirts) is the core indicator for the design of insulator umbrella spacing, which directly affects the critical value of ice bridging and the effective space of hot water jet; l 2 is the axial net distance between the main skirt and the auxiliary skirts (medium / small skirts), which is a secondary core spacing parameter that takes into account both creepage distance and icing suppression effect; l 3 represents the axial net spacing between the auxiliary skirts (medium / small skirts), which is a refined spacing parameter used to optimize the overall dirt accumulation characteristics and jet flow channels of the skirts.

[0037] h 1 represents the total radial extension height of the maximum skirt (large / extra-large skirt), which is the vertical distance from the outer wall of the core rod to the edge of the maximum skirt, corresponding to the maximum skirt extension p1 in the definition of k1; h 2 represents the total radial extension height of the middle umbrella skirt (middle umbrella skirt), which is the vertical distance from the outer wall of the core rod to the edge of the middle umbrella skirt, and is a transitional extension parameter; h 3 represents the total radial extension height of the minimum umbrella skirt (small umbrella skirt), which is the vertical distance from the outer wall of the core rod to the edge of the small umbrella skirt, corresponding to the minimum umbrella skirt extension p2 in the definition of k1.

[0038] Furthermore, the combination method of the umbrella skirts and the final umbrella shape were determined. A differentiated design was implemented for the composite insulator, with the repeating unit of the umbrella skirts designed as a "large-medium-small-medium-small" umbrella. Taking the minimum umbrella skirt diameter D3 as 80mm, the umbrella shape structure of the optimized composite insulator for the light ice zone was obtained after fine-tuning the spacing of the large umbrellas, as shown below. Figure 4 As shown.

[0039] The jet adaptation characteristics used in the light ice zone: the inclination angle of the upper surface of the umbrella skirt and the differentiated umbrella diameter form a flow guiding channel, so that the hot water jet (temperature 60-90℃, outlet pressure 0.5-1.5MPa) can be evenly covered along the umbrella surface.

[0040] For the design of composite insulator umbrella structures in medium-ice zones, a composite insulator umbrella structure suitable for medium-ice zones is designed with d=15mm as the base ice thickness and d=20mm as the maximum ice thickness. The ice flashover performance is improved by adding extra-large umbrella skirts.

[0041] Furthermore, the number of extra-large umbrellas N1 and D1 are determined. More N1 will increase the number of air gaps, which is beneficial to the uniform distribution of potential in each air gap and improves the ice flash voltage. However, it will also cause a decrease in d1. Under moderate icing, it is easy to be bridged by ice ridges. A trade-off must be made between d1 and N1. We choose d1=450mm and N1=4.

[0042] Furthermore, when d1 = 450 mm, the calculated values ​​of Ec for d = 15 and 20 mm are as follows: Figure 5 As shown, the values ​​of D1 and D2 are as follows: Figure 5 As shown in the dashed box.

[0043] Furthermore, D1 and D2 were determined, and the umbrella structure was designed with Ec, CF coefficient, and k1 as the priority order. At the same time, the medium ice zone was further divided into lightly polluted (Level I and II) zones and heavily polluted (Level III and IV) zones according to the pollution level.

[0044] The values ​​of D1 and D2 can be used to calculate k1 and the maximum CF coefficient of a single super-large umbrella unit, as shown in Table 2 below: Table 2 Maximum CF Coefficient Table

[0045] For medium-sized ice zones with heavy pollution, select D1=230mm and D2=140mm; for medium-sized ice zones with light pollution, select the combination of D1=250mm and D2=150mm.

[0046] Furthermore, the grouping method of the umbrella skirts was determined. Given d1=450mm, a maximum of 14 umbrellas can be interspersed between two extra-large umbrella skirts. For medium-icing areas with heavy pollution, to maximize creepage distance, the repeating unit of the umbrella skirts is designed as a quasi-"large-small" umbrella; for medium-icing areas with light pollution, the umbrella skirt unit is designed as a quasi-"large-small-medium-small" umbrella. This design, while ensuring the creepage distance meets requirements, delays the bridging of large umbrellas with a diameter of D2 by icicles, and also exhibits superior pollution accumulation characteristics. Based on the above approach, the designed composite insulator umbrella structures for medium-icing areas with light and heavy pollution are as follows: Figure 6 and Figure 7 As shown.

[0047] The jet-assisted design adopted in the medium ice zone: the spacing between the oversized umbrella and the regular umbrella is adapted to the distribution of jet impact force, the hot water jet uses a conical nozzle, the spray distance is controlled at 1.5~2.8m, the water conductivity is ≤500μS / cm, and the leakage current does not exceed 1mA. Through the synergistic effect of jet impact force and umbrella tilt angle, the middle ice layer is caused to crack and fall off.

[0048] For the design of composite insulator umbrella structures in heavy icing areas, the umbrella structure is optimized based on an ice thickness of d=30mm, which can improve the icing insulation performance of composite insulators within a certain ice thickness range. Furthermore, the optimization targets improved insulators with extra-large skirts, and is based on the design optimization in medium icing areas with relatively light pollution accumulation.

[0049] Furthermore, in insulators with a diameter of d=30mm and less contamination in medium-iced areas, the extra-large insulator skirts will be bridged by ice ridges. Therefore, two different diameters of extra-large insulator skirts can be selected and installed alternately in other insulator skirts to reduce the time required for ice ridge bridging. The optimized composite insulator is as follows: Figure 8 As shown.

[0050] Furthermore, when the ambient wind speed is low (≤3m / s), the first extra-large umbrella can be replaced with a smaller diameter ordinary large umbrella (150mm) to increase the ice resistance when the umbrella skirt is bridged by icicles. The optimized composite insulator is as follows: Figure 9 As shown.

[0051] The heavy icing zone employs a jet enhancement design: it is adapted to high-pressure hot water jets (temperature 90-120℃, outlet pressure 1.5-3.0MPa), and the jets penetrate to the root of the ice ridges along the umbrella surface guide channel.

[0052] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0053] This specification and accompanying drawings are merely illustrative examples of the present invention and are intended to cover any and all modifications, variations, combinations, or equivalents within the scope of the present invention. Clearly, those skilled in the art can make various alterations and modifications to the present invention without departing from its scope. Therefore, if such modifications and variations fall within the scope of the present invention and its equivalents, the present invention intends to include these modifications and variations.

Claims

1. A design method for composite insulator skirts that adapts to different ice zones and synergistically supports thermal jet de-icing, characterized in that, The main structure of the composite insulator adopts a graded and adjustable modular umbrella skirt assembly, which adapts to the icing characteristics of light ice, medium ice and heavy ice zones through differentiated umbrella diameter, tilt angle and spacing parameters, and is coupled and adapted with the parameters of hot water jet de-icing technology. The main structure of the composite insulator meets the following pollution zone design requirements: The creepage distance of composite insulators should be 0.75 to 1 times that of porcelain insulators in the same pollution area. The icing coefficient CF is less than 3.2 in pollution zones I and II, and less than 3.8 in pollution zones III and IV; The spacing between adjacent umbrella skirts is greater than 30mm, the difference in umbrella diameter for umbrella structures with unequal diameters is not less than 30mm, the ratio of the radial extension of the insulator skirt to the axial spacing matching characteristic k2 is not less than 0.8, and the ratio of the maximum skirt diameter to the insulator core rod diameter k3 does not exceed 5.

0. The upper surface of the umbrella skirt has an inclination angle of 10-16°, the lower surface has an inclination angle of 3-8°, and the rod diameter is uniformly 32-36mm to adapt to the heat conduction and impact force transmission of hot water jets.

2. The composite insulator skirt design method according to claim 1, characterized in that, The criteria for classifying ice zones are as follows: ice thickness d < 10 mm is a light ice zone, 10 mm ≤ d < 20 mm is a medium ice zone, and d ≥ 20 mm is a heavy ice zone.

3. The composite insulator skirt design method according to claim 1, characterized in that, The umbrella-shaped structure of the graded adjustable modular umbrella skirt assembly and the hot water jet parameters satisfy the following coupling relationship: the umbrella skirt spacing matches the jet diffusion angle, the umbrella surface tilt angle is at an angle of 15~30° with the jet impact angle, and the umbrella diameter difference is adapted to the kinetic energy distribution in the jet core area.

4. The composite insulator skirt design method according to claim 1, 2 or 3, characterized in that, The light icing zone uses an ice thickness of d=5mm as the baseline and d=10mm as the maximum ice thickness, and is optimized for conventional umbrella shapes. Specific parameters include: Umbrella spacing: determined by formula Calculate the critical umbrella spacing for the transition of ice tip arc discharge mode when ice coverage is 5mm. Through formula Calculate the critical umbrella spacing for icicle bridging when the icing is 10mm. The optimized maximum umbrella spacing d1=(d 1s-5 +d 1b-10 ) / 2; where D1 and D2 are the maximum and second largest skirt diameters, respectively; Umbrella diameter parameters: Based on the actual requirements of the light icing zone, the umbrella structure is designed with priority order of creepage coefficient, flashover critical field strength Ec, and the ratio of the difference between the maximum umbrella skirt extension p1 and the minimum umbrella skirt extension p2 to the maximum umbrella skirt extension p1, k1, to determine D1, D2, and d; the composite insulator is designed differently, and the repeating unit of the umbrella skirt is designed as a "large umbrella skirt - medium umbrella skirt - small umbrella skirt - medium umbrella skirt - small umbrella skirt" structure, where the large umbrella skirt refers to the largest umbrella skirt, the small umbrella skirt refers to the smallest umbrella skirt, and the medium umbrella skirt refers to the umbrella skirt between the largest and smallest umbrella skirts; The hot water jet adaptation characteristics are: the inclination angle of the upper surface of the umbrella skirt and the differentiated umbrella diameter form a flow guiding channel, so that the hot water jet can be evenly covered along the umbrella surface.

5. The composite insulator skirt design method according to claim 4, characterized in that, In the hot water jet adaptation characteristics of the light ice zone, the hot water jet temperature is 60-90℃ and the outlet pressure is 0.5-1.5MPa.

6. The composite insulator skirt design method according to claim 1, 2 or 3, characterized in that, In the medium-ice zone, the ice thickness is based on d=15mm and the maximum ice thickness is d=20mm. The jet de-icing effect is enhanced by adding an extra-large umbrella skirt. Specific design features include: Extra-large umbrella parameters: maximum umbrella spacing d1=450mm, number of extra-large umbrellas N1=4, the umbrella structure is designed with priority order of flashover critical field strength Ec, creepage coefficient, the ratio of the difference between the maximum umbrella skirt extension p1 and the minimum umbrella skirt extension p2 to the maximum umbrella skirt extension p1 k1; at the same time, the maximum umbrella skirt diameter D1 and the second largest umbrella skirt diameter D2 are selected according to the pollution level. Umbrella skirt combination method: Level III and IV contaminated areas adopt a quasi-"large umbrella skirt-small umbrella skirt" repeating unit, while Level I and II contaminated areas adopt a quasi-"large umbrella skirt-small umbrella skirt-medium umbrella skirt-small umbrella skirt" repeating unit; Jet-assisted design: The spacing between the oversized umbrella and the regular umbrella is adapted to the distribution of jet impact force. The hot water jet uses a conical nozzle with a spray distance controlled between 1.5 and 2.8 m. The water conductivity is ≤500 μS / cm and the leakage current does not exceed 1 mA. Through the synergistic effect of the jet impact force and the umbrella tilt angle, the middle layer of ice is cracked and detached.

7. The composite insulator skirt design method according to claim 6, characterized in that, The umbrella diameter parameters for the medium ice zone are as follows: for Class III and IV contaminated areas, D1=230mm and D2=140mm are selected; for Class I and II contaminated areas, D1=250mm and D2=150mm are selected.

8. The composite insulator skirt design method according to claim 6, characterized in that, The contraction angle of the conical nozzle is 30~50°.

9. The composite insulator skirt design method according to claim 1, 2 or 3, characterized in that, The heavy icing zone uses an ice thickness of d=30mm as the baseline and employs a double-diameter extra-large umbrella skirt arrangement. Specific design features include: Extra-large umbrella configuration: Select extra-large umbrella skirts with diameters of 300mm and 230mm and install them in a cross pattern, with a spacing of 450mm between adjacent extra-large umbrellas, and match them with regular umbrella skirts of 150mm, 120mm and 90mm. Low wind speed adaptation: When the ambient wind speed is ≤3m / s, the first extra-large umbrella is replaced with a 150mm ordinary large umbrella to increase the ice layer resistance and the jet action area. Jet enhancement design: Adapted to high-pressure hot water jets, the jets penetrate to the root of the ice ridges along the umbrella surface guide channel.

10. The composite insulator skirt design method according to claim 1, characterized in that, When using hot water jet adapter, safety protection design is also included: by optimizing the umbrella-shaped electric field distribution, the water column insulation distance during live work meets the preset standard, the leakage current monitoring threshold is set to 1mA, and the spray distance can be adjusted within the range of 5~15m.

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