Power enterprises must attach great importance to lightning protection technology in the operation of power transmission lines, combining the construction scale, laying route, and regional environment of the transmission lines to equip with complete lightning protection devices, ensuring that the lines have strong lightning protection capabilities. This paper mainly conducts a comprehensive analysis of the lightning protection technology in the operation of transmission lines, and proposes specific countermeasures for the efficient use of lightning protection technology. It also explains how to update the lightning protection technology, aiming to provide reference for relevant personnel.

In recent years, the number of high-voltage line trips caused by lightning strikes has been increasing, which not only affects the normal operation of power supply equipment but also endangers the reliability of power supply. Lightning-induced trips of overhead power transmission lines have always been a problem for safe power transmission. To reduce lightning-induced trips of high-voltage lines, relevant personnel must also take corresponding measures to ensure the normal operation of power supply lines.

1. The Impact of Lightning Strikes on Power Transmission Lines

When power transmission lines are struck by lightning, they will be damaged by their own heat, causing the metal materials in the corresponding equipment to melt. In addition, the high voltage produced in an instant by the lightning strike will also damage the protective devices of the transmission lines, leading to fires. These damages to the transmission lines are direct and irreparable. Moreover, the electromagnetic field produced will affect the normal operation of the transmission lines. After being struck by lightning, the transmission lines will be unable to operate stably due to excessive pressure. The corresponding current produced will also damage the relay protection devices, bringing certain impacts to people’s lives. Therefore, lightning strikes have many impacts on power transmission lines, which should be fully considered in the design process to reduce the impact of lightning strikes on power transmission lines.

2. The Working Principle of Lightning Protection Grounding

The design of lightning protection grounding is based on the principle of lightning strikes. The main purpose of the design is to guide the energy generated by lightning into the ground through artificial design, to effectively protect buildings and electrical equipment. Due to the evaporation effect, moisture enters the atmosphere and condenses into ice crystals when it encounters cold air, forming cumulonimbus clouds. During the atmospheric movement, the cloud layer will carry electric charges, creating a charge induction between the earth and the cloud layer, similar to a capacitor with opposite charges. When these charges accumulate to a certain extent, they will puncture the atmosphere layer, resulting in a lightning strike. People have further analyzed and designed lightning protection grounding equipment that uses metal conductors to attract lightning currents, setting up grounding networks in the ground in advance, allowing the current to be guided into the ground through the network, to reduce the damage to buildings by strong currents from lightning strikes.

3. Lightning Protection and Grounding Technology

Selecting a Reasonable Power Transmission Line Path
Since the generation of lightning activity has certain necessities and particularities, power companies cannot completely avoid the existence of lightning activity when erecting power transmission lines. It is necessary to try to avoid lightning strike areas to reduce the damage to power transmission lines. Generally, the most common lightning strike areas are mainly divided into the following aspects: First, areas with high groundwater levels or groundwater containing easily conductive minerals. Second, for the junction area between hills and plains, the terrain will undergo large changes, which will produce lightning strike areas. Third, there is a sudden change in the resistivity of the soil in the area or there are fault zones. Fourth, wind-prone areas in mountainous areas or gorges at mountain passes. Fifth, the sunny side of the top of hills and mounds where vegetation is lush. Sixth, there are areas with forests, lakes, rivers, ponds, and reservoirs.

Distribution Line Grounding Lightning Protection The most commonly used technology in the power system is still lightning lines and lightning arresters as the main lightning protection measures. The selection and layout of these two lightning protection devices need to be distinguished according to the specific situation of the specific use occasion, and different situations will produce different results. That is to say, this traditional equipment has certain limitations in materials, which also determines the limitations of the use quality of the power distribution system. For example, for 10kV bare conductor lines, using lightning rods as the main means is sufficient. However, lightning lines are expensive and the construction is complex, so they are not commonly used at present. People often choose to install lightning arresters in areas with frequent lightning activity. 10kV insulated lines widely use cross-linked polyethylene processed insulated lines under the background of power grid transformation, which have a certain insulating function. However, in order to protect the power grid system, it is necessary to install lightning arresters. If it is a low-voltage line, installing low-voltage lightning protection devices at the transformer outlet can achieve the ideal protection effect.

Automatic Reclosing Setting The scientific setting of automatic reclosing protection can be done in the first place when the current or voltage is abnormal, to do a good job in power-off protection, to reduce the impact of lightning strikes on power transmission lines, to maintain the safety of power transmission lines, and to reduce the occurrence of losses and dangers. At present, the existing automatic reclosing in China is mainly divided into four types: single-phase devices, three-phase devices, composite devices, and inactivated devices. After the power transmission line is affected by lightning, the relay protection of the automatic reclosing will immediately start, achieving the closure of the lightning strike section, and ensuring the overall quality of the power transmission line by power-off to ensure the transmission of electrical energy on other sections. The probability of power transmission lines being affected by lightning and power failure is very high, and the technology of instantaneous power-off and instantaneous reclosing chain needs to be improved. This requires professional personnel to continue to carry out research to optimize the technical level of automatic reclosing and give full play to its advantages in work, to maintain the safe operation of power transmission lines. For example, the installation of dual automatic reclosing: First, ensure the consistency of equipment types and specifications, and try to purchase related equipment from the same manufacturer. Dual automatic reclosing needs to be installed in two independent protective devices to ensure its normal operation. During operation, there is no need for too much debugging work, and operators only need to operate one reclosing to exert protective performance. When debugging the associated equipment of the reclosing, in addition to strictly following the specified requirements, it is also necessary to carry out in-depth processing on the transformer equipment, and install low-voltage surge arresters on both the low and high sides to promote good operation of the equipment. Finally, do a good job in the maintenance of lightning arresters, poles, and ground networks, replace the original bare conductors with insulated overhead lines, and control short-circuit faults.

Reducing the Grounding Resistance of Iron Towers The main anti-lightning protection measures adopted by most power companies are to reduce the grounding resistance of power transmission lines. At the same time, the main methods for reducing the grounding resistance of transmission line towers in the industry are mainly divided into the following aspects: First, if the power transmission line is small in area and scale, but the grounding network area is relatively concentrated, then workers can apply a layer of grounding agent on the surface of the grounding resistance, which can reduce the size of the grounding resistance value. Because the process is relatively simple and the effect is good, it is widely promoted and used. Second, use blasting grounding technology. First, in the area where the grounding resistance needs to be reduced, use blasting technology to crack the ground, and then use a pressure machine to press materials with lower resistivity into the cracks to reduce the conductivity of the surrounding soil. Third, there is a positive correlation between the length of the horizontal grounding resistance and the inductive effect that can be played. Therefore, the grounding resistance value can be reduced by increasing the horizontal length of the grounding resistance. Industry research has found that for horizontal grounding resistance, if its length is 55m, then the resistivity is 500Ω/m. If the length of the horizontal grounding resistance is increased to 80m, at this time, the resistivity will rise to 2000Ω/m. Therefore, by increasing the length of the horizontal grounding resistance, the impact coefficient of the resistance can be reduced, and the impact coefficient can be controlled within a stable and reasonable range, which can reduce the grounding resistance of the iron tower.

Setting Up Lightning Lines Lightning lines can effectively divert lightning and shield the impact of lightning on power transmission lines when lightning strikes occur. Lightning lines are grounding lines, but they are not directly grounded, but grounded through the tower, which can better protect the power transmission lines. Usually, in the anti-lightning protection of power transmission lines, the insulators of lightning lines must leave some gaps to prevent the large current on the lightning line from generating a large magnetic field and affecting the power transmission lines.

Avoiding Dense Areas Because the tower is in the external environment, this leads to the position and reasons of the power transmission line being very complex during the problem process. Through the data of the power department, it can be found that at least more than 50% of the faults are caused by lightning strikes. Therefore, in the design

process of the power transmission line, it is necessary to avoid areas such as water areas and canyons. When the power transmission line passes through the plain area, lightning will damage the corresponding facilities of the power transmission line through direct lightning strikes. Therefore, on the basis of meeting the corresponding requirements, it should be possible to reduce the impact grounding resistance. For some areas with frequent lightning, it is necessary to equip them with corresponding lightning lines to better let the power transmission line play its own performance and avoid faults caused by lightning strikes.

New Grounding Bars The limitations and insufficiencies in traditional grounding and lightning protection have stimulated people’s research and innovation in this area. At present, new grounding bars are actively promoted in China.

New grounding bars are mainly made of copper-plated steel, with a single length of up to 1.22 meters, which can be assembled with threaded connectors at will to reach the national standard grounding value. Moreover, this material has strong corrosion resistance, and the conductivity is far higher than that of steel materials. A large investment is needed for the initial installation, but there is no need to spend more costs on maintenance and maintenance later. The material has good performance, long life, and excellent quality. In addition, the small diameter and convenient installation operation make the construction difficulty relatively small, avoiding large-scale construction and reducing damage to the surrounding environment. The use of this high-performance grounding bar has significantly improved the safety and stability of the power distribution system.

Conclusion Lightning protection is crucial for the safe transmission of power lines, and various lightning protection technologies can effectively improve the lightning resistance level of power transmission lines. This paper adopts a differentiated lightning protection transformation strategy, carries out lightning protection transformation of the lines, and makes rational use of various lightning protection technologies, taking into account the dual goals of reducing construction costs and transforming lightning protection facilities, effectively reducing the lightning strike trip rate of power transmission lines.