CN103123832B - Umbrella-shaped structure of ultra/extra-high voltage alternating current composite insulator - Google Patents

Abstract

The invention provides an ultra/extra-high voltage alternating current composite insulator umbrella structure from the aspects of optimizing umbrella design and improving creepage distance utilization rate, wherein the umbrella structure consists of large umbrellas with equal diameters and small umbrellas with equal diameters, and the large umbrellas and the small umbrellas are alternately arranged; the creep coefficient of the composite insulator is 3.8-4.2. By adopting the umbrella-shaped composite insulator, under the hydrophilic condition, the pollution flashover voltage of the unit insulation height is higher than that of the umbrella-shaped composite insulator used for one large umbrella-shaped composite insulator, two small umbrella-shaped composite insulators used for 1000kV extra-high voltage test demonstration engineering; the length of the composite insulator string required by areas with different pollution degrees can be reduced to different degrees, so that the size of the pole tower is optimized, and the manufacturing cost of the power transmission line is greatly saved.

Description

An EHV/UHV AC Composite Insulator Umbrella Structure

technical field

The invention belongs to the technical field of design and manufacture of high-voltage insulators, and in particular relates to an umbrella-shaped structure of an ultra/ultra-high voltage AC composite insulator.

Background technique

The insulator is an essential part of the high-voltage transmission line. It connects the metal wire to the tower, and at the same time withstands the potential difference between the wire and the tower to ensure the safe and stable operation of the transmission line. After running for a certain period of time, the surface is dirty, and under the influence of climatic conditions such as heavy fog and drizzle, discharge may occur along the wet and dirty insulating surface, or even penetrating discharge, resulting in insulation failure, that is, pollution flashover occurs (hereinafter referred to as pollution flashover). Pollution flashover will cause power outages and cause huge economic losses. Therefore, the pollution flashover resistance of insulators is one of the most important indicators to measure its performance.

Composite insulators are a kind of insulators, also known as composite insulators. Since the outer insulation is made of silicone rubber, they have strong pollution flashover resistance under dirty and wet conditions. In recent years, they have been widely used on EHV/UHV transmission lines. In the UHV 1000kV Anhui-East Transmission Project, the use of composite insulators has greatly surpassed traditional porcelain and glass insulators, and composite insulators will also be mainly used in future UHV power transmission projects. Therefore, improving the anti-pollution flashover ability of high-voltage composite insulators is of great significance to EHV/UHV transmission projects.

The composite insulator's umbrella shape and its surface hydrophobicity jointly affect the pollution flashover characteristics of the insulator. When the surface hydrophobicity is the same, the design of the umbrella structure determines the pollution flashover characteristics of the composite insulator. Under the same voltage application conditions, the better umbrella design can increase the flashover voltage per unit insulation height, thereby shortening the insulation length required for safe operation, thereby reducing the overall size of the tower, and greatly saving the tower investment.

In the prior art, the design and manufacture of the composite insulator's umbrella shape, the umbrella shape of the composite insulator produced by various domestic manufacturers is quite different. There are mainly equal-diameter umbrellas as shown in Figure 1, one large and two small umbrellas as shown in Figure 2, and other umbrella shapes (such as large-medium-small umbrellas, etc.).

The umbrella shape and parameters commonly used for composite insulators are described below in combination with Figure 1 and Figure 2, which are defined as follows:

Insulator body: the middle insulating part of the insulator from which the umbrella protrudes;

Umbrella: The protruding insulating part on the body of the insulator to increase the creepage distance;

Creepage distance: the shortest distance or the sum of the shortest distances along the insulating surface between two parts of the insulator that normally carry the operating voltage;

Insulation length: the straight length of the entire insulation body of the insulator;

Creepage coefficient/CF: The ratio of the total creepage distance of an insulator to the insulation length, dimensionless. Indicates the creepage distance per unit insulation length, which is one of the important parameters of insulator design;

Umbrella spacing: the axial distance between umbrellas;

Umbrella extension: the radial distance between the outermost edge of the umbrella and the mandrel jacket.

Existing composite insulator designs tend to blindly pursue a larger creepage distance, and seldom consider the role of the optimized umbrella design in improving the pollution flashover voltage, so the pollution flashover voltage per unit insulation height is low.

Contents of the invention

In order to overcome the deficiencies of the above-mentioned prior art, starting from optimizing the umbrella design and improving the utilization rate of the creepage distance, through a large number of systematic pollution flashover tests of the lifting method, the present invention provides an umbrella structure for EHV/UHV AC composite insulators, Using this umbrella-shaped composite insulator, under hydrophilic conditions, the pollution flashover voltage per unit insulation height is higher than that of one large and two small umbrella-shaped composite insulators used in the 1000kV UHV test demonstration project; it can reduce areas with different pollution degrees to varying degrees The string length required for composite insulators optimizes the size of the tower and greatly saves the cost of transmission lines.

In order to realize the above-mentioned purpose of the invention, the present invention takes the following technical solutions:

Provide an ultra/ultra-high voltage AC composite insulator umbrella structure, the umbrella structure is composed of large umbrellas with equal diameters and small umbrellas with equal diameters, the large umbrellas and small umbrellas are arranged alternately; the creepage of the composite insulator The coefficient is 3.8-4.2.

The preferred solution of the present invention is that the distance between adjacent umbrellas is not less than 20 mm, and the distance between the umbrellas of the large umbrellas is not less than 70 mm and not greater than 100 mm.

Another preferred solution of the present invention is that the distance between adjacent umbrellas is not less than 30 mm, and the distance between the umbrellas of the large umbrellas is not less than 75 mm and not greater than 90 mm.

The preferred solution of the present invention is that: the umbrella extension of the large umbrella is not less than 70mm, and the difference between the umbrella extension of the large umbrella and the umbrella extension of the small umbrella is not less than 20mm.

Another preferred solution of the present invention is that: the umbrella extension of the large umbrella is not less than 80mm, and the difference between the umbrella extension of the large umbrella and the umbrella extension of the small umbrella is not less than 30mm.

A preferred solution of the present invention is that: the ratio of the umbrella pitch of the large umbrella to its umbrella extension is not less than 0.8 and not greater than 1.0.

Another preferred solution of the present invention is that: the ratio of the umbrella pitch of the large umbrella to its umbrella extension is not less than 0.85 and not greater than 1.0.

Under the condition that the salt density is 0.1mg/cm ² , the dust density is 1.0mg/cm ² and the surface is hydrophilic, the pollution flashover voltage per unit insulation height of the composite insulator is not less than 140kV/m.

Compared with prior art, the beneficial effect of the present invention is:

1. The composite insulator umbrella structure provided by the present invention increases the creepage distance while reducing the probability of arc bridging between umbrellas, thereby increasing the pollution flashover voltage;

2. At the same time, in the design, it is considered that although the creepage distance of the densely distributed shed design under heavy salt density is relatively high, it will cause the sheds to be easily bridged by arcs, which will reduce the pollution flashover voltage, so the selected Appropriate creepage coefficient range makes the utilization of creepage distance high;

3. The present invention adopts an optimized umbrella design, and the flashover voltage per unit insulation height of the composite insulator designed by the present invention is higher than that of other products, so the anti-pollution flashover ability is excellent, and the cost of the transmission line can be saved while improving the reliability of the external insulation of the transmission line ;

4. The present invention has wide applicability and can be widely used in rod-shaped suspension composite insulators, pillar composite insulators, insulating pillars, interphase spacers, lightning arresters and other equipment in AC 500kV, 750kV, and 1000kV super/ultra-high voltage transmission projects.

Description of drawings

Fig. 1 is a schematic diagram of a composite insulator with an equal-diameter umbrella structure in the prior art;

Fig. 2 is a schematic diagram of a composite insulator with one large and two small umbrella structures in the prior art;

Fig. 3 is the composite insulator schematic diagram of one large and one small umbrella structure provided by the present invention;

Among them, 1-mandrel, 2-sheath, 3-big umbrella shed, 4-small umbrella shed.

detailed description

The present invention will be described in further detail below in conjunction with the accompanying drawings.

As shown in Fig. 3, the present invention provides a kind of EHV/UHV AC composite insulator umbrella structure, composite insulator includes mandrel 1, sheath 2, and umbrella structure, and described umbrella structure comprises the big umbrella of equal diameter and equal diameter The small umbrellas, the large umbrellas and small umbrellas are arranged alternately; the creepage coefficient of the composite insulator is 3.8-4.2.

Example 1

The structural height of the composite insulator is 9000mm, the insulation distance is 8360mm, and the creepage distance is 32250mm. The umbrella spacing of the large umbrella is 90mm, the umbrella extension of the large umbrella is 90mm, and the umbrella extension of the small umbrella is 55mm. The insulator can be applied to suspension insulators of 1000kV UHV AC transmission lines.

Example 2

The structural height of the composite insulator is 4400mm, the insulation distance is 4000mm, and the creepage distance is 16700mm. The umbrella spacing of the large umbrella is 80mm, the umbrella extension of the large umbrella is 90mm, and the umbrella extension of the small umbrella is 55mm. The insulator can be applied to suspension insulators of 500kV ultra-high voltage AC transmission lines.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: the present invention can still be Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention shall be covered by the scope of the claims of the present invention.

Claims (1)

1. A super/ultra-high voltage AC composite insulator umbrella structure, characterized in that: the umbrella structure is composed of large umbrellas with equal diameters and small umbrellas with equal diameters, and the large umbrellas and small umbrellas are arranged alternately; The creepage coefficient of the composite insulator is 3.8~4.2; The spacing between adjacent umbrellas is not less than 20mm, and the spacing between the umbrellas of the large umbrellas is not less than 70mm and not greater than 100mm; The umbrella extension of the large umbrella is not less than 70mm, and the difference between the umbrella extension of the large umbrella and the umbrella extension of the small umbrella is not less than 20mm; The ratio of the umbrella spacing of the large umbrella to its umbrella extension is not less than 0.8 and not greater than 1.0; Under the condition that the salt density is 0.1mg/cm ² , the dust density is 1.0mg/cm ² and the surface is hydrophilic, the pollution flashover voltage per unit insulation height of the composite insulator is not less than 140kV/m.