In recent years, with the rapid development of China's reform and opening up economy, the living standards and socialization of residents have been greatly improved, the electricity consumption of each household has also increased accordingly, and the total electricity consumption scale has also been qualitatively improved. This has put forward new requirements for China's electric power industry, and also promoted the development of the electric power industry to a certain extent. The research shows that the failure rate of overhead insulated conductors caused by lightning damage and tripping accounts for more than 70% of the total faults, which seriously affects the normal operation of the power system and causes huge economic losses to the power enterprises. Therefore, power companies strengthen the lightning break and lightning trip textile technology of overhead insulated wires to ensure the stable operation of distribution lines.

1. Overhead insulated wires are affected by lightning.

Overhead insulated wires are subject to different degrees and types of lightning, and the obstacles that arise are also different. For example, when a multi-phase fault occurs in an overhead insulated wire hit by lightning, the counterattack of lightning will cause other faults. First of all, the occurrence of tripping phenomenon, continuous tower equipment often appear abnormal flash phenomenon. The position selection of the regular triangle array will be abnormal. The line in the horizontal middle line will also appear short line phenomenon. For the excitation phenomenon of lightning, the one-way short-circuit error occurs in overhead insulated conductors.

However, the lightning phenomenon of the overhead insulated wire of the whole system has a great influence on the whole system, especially the commonly used 10kV overhead insulated wire. The error conditions are as follows: First, it is easy to be struck by lightning. 2. tripping phenomenon; third, the connected electrical equipment may be damaged by lightning. Fourth, there may be abnormal insulator flashover, threatening the safety of life and property. In addition, lightning strikes of overhead insulated wires generally occur under relatively bad weather conditions, and lightning strikes during the rainy season are likely to cause the dumping of large trees. In this case, if a reasonable solution is not taken as soon as possible, there will be a connection phenomenon, and even passers-by will get an electric shock, which will seriously affect people's production and life.

2. Causes of lightning disconnection and tripping of overhead insulated conductors

It is reported that at this stage in China's overhead insulated conductors, the insulation performance is relatively low, generally only the power distribution energy at normal temperature, and can not play any role in the face of strong high currents such as lightning. Generally speaking, a current of 5-7KA will cause a trip fault of the overhead insulated conductor, but the current generated in the case of a lightning strike is about 40KA. When the overhead insulated conductor is exposed to lightning, lightning damage and tripping will occur. For overhead insulated conductors, which are actually vulnerable to lightning strikes, the following reasons are summarized. One is the 50% discharge voltage of the insulator of the overhead insulated wire; the insulator flashover fault. Lightning is prone to insulator flashover, which may damage the insulator. When a thunderstorm occurs, the overvoltage caused by lightning will increase the load of the distribution line and quickly exceed the voltage on both sides of the insulator, which will cause a series of flash problems. In addition, the insulator is exposed for a long time, and it is easy to be heated and damaged by the outside natural weather. At this time, the insulator with better insulation should be used for replacement. The intensity of the lightning current is very large. The grounding resistance of the tower in the overhead insulated conductor is relatively small. However, there are a series of lightning protection device settings for high-voltage lines, which can avoid the phenomenon of high-voltage line tripping, but the irregular construction of these lightning protection measures at this stage is also an important factor in the lightning break and trip phenomenon of overhead insulated conductors.

3, overhead insulated wire lightning damage and trip prevention technology.

3.1 Lightning Protection Technology

Applying the "switching" lightning protection technology to the actual overhead insulated conductor can effectively increase the power resistance of the transmission line. Relevant technicians protect the insulator string by inducing lightning flashover and frequency arc, effectively ensuring the success probability of reclosing. In practical applications, electricians can implement two technical solutions: First, set the parallel spacing of insulator strings reasonably. In order to make the insulator string and the equipment in the gap work properly, the distance between the two is set so that it is within the dry arc length of the insulator string. However, it should be noted that this technical solution is not suitable for the use of high-voltage overhead insulated wires. Electricians shall install line type lightning arresters. The main chemical composition of this type of lightning protection device is zinc oxide. Its role is mainly manifested in the following aspects. The arrangement of the device can effectively improve the lightning protection performance of the entire overhead insulated wire. It can effectively improve the anti-lightning performance of the overall overhead insulated wire. The tripping phenomenon when overhead insulated wires are struck by lightning can be greatly reduced.

Analysis of Overvoltage Protection Strategy for 3.2 Distribution Line

(1) Strengthen line insulation

The strengthening of line insulation is generally accompanied by cost problems and cost problems. From an economic point of view, strengthening the line insulation level needs to ensure the normal operation of the line, can ensure the basic requirements of the internal voltage, and can be combined with the actual situation for comprehensive analysis. Blindly raising the line insulation level will be counterproductive. Therefore, in the process of strengthening the line insulation capacity, to ensure efficiency and rationality, a detailed analysis of various factors to ensure the efficiency and rationality of strengthening line insulation, and a detailed analysis of various factors. For example, if you want to improve the actual impact insulation strength of the insulator string in the line, you can use wooden poles instead of cement, and the weakness can improve the actual insulation of wooden poles, you can try not to use steel bars to avoid lightning current during lightning impact exceeding the average electric field strength, thereby maintaining the wooden pole arc. Therefore, wood crossbars that conform to the actual situation should be used to ensure that the average electric field strength of the board meets the basic requirements. Only in this way can the actual safety of the wooden pole line be guaranteed, and there will be no tripping problems caused by lightning.

(2) Use of insulation facilities

In the lightning protection countermeasures of distribution line operation, the first thing to pay attention to is the use of lightning protection materials and lightning arresters. As an important measure of lightning protection, insulating materials play an important role in the prevention of lightning accidents, which can reduce the impact of lightning accidents to a certain extent. At present, the distribution line itself is very complex, the line contains a lot of metal materials, so only to strengthen the insulation capacity of the distribution line, in order to prevent lightning accidents. To this end, the relevant personnel carefully check the insulation capacity of the distribution line, the aging of the insulation material in a timely manner to maintain, select the appropriate insulation material for replacement. In addition, some insulation facilities (such as lightning arresters, etc.) should be installed in time. The lightning arrester has the characteristics of good lightning protection effect and convenient installation, which can well prevent lightning accidents. But like the insulation material on the distribution line, the arrester is also a facility that is prone to aging. Therefore, it is not only necessary to carry out corresponding maintenance work on the arrester, but also to set up some facilities matching the arrester to strengthen the role of the arrester.

4. Conclusions

To sum up, the lightning blocking and tripping phenomenon of overhead insulated conductors have a great impact on the entire power system, and various faults may occur in the entire power supply and distribution system. Therefore, relevant electricians should effectively prevent lightning strikes on overhead lines and select appropriate Lightning protection devices further ensure the safety of overhead distribution lines.